Copper‐Catalyzed Asymmetric Silylation of Propargyl Dichlorides: Access to Enantioenriched Functionalized Allenylsilanes

Abstract A copper‐catalyzed silylation of propargyl dichlorides was developed to access chloro‐substituted allenylsilanes under mild reaction conditions. Moreover, enantioenriched chloro‐substituted allenylsilanes can be synthesized in moderate to high yields and good enantioselectivities with this protocol.

Prepared according to the general procedure A using corresponding aldehyde (3.2 g, 32.6 mmol). The product 1t was isolated in 37% yield (1.87 g) by column chromatography as pale yellow oil. Prepared according to the general procedure A using corresponding aldehyde (1.95 g, 13.9 mmol). The product 1u was isolated in 84% yield (2. Prepared according to the general procedure B using corresponding aldehyde (2.24 g, 12.9 mmol). The product 1v was isolated in 56% yield (1.64  Prepared according to the general procedure A using corresponding aldehyde (1.4 g, 11.1 mmol). The product 1w was isolated in 50% yield (1. 3a: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then removed it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1a (37 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 2 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3a (45.0 mg, 79%) as yellow oil. 1  3b: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then removed it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1b (39.8 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3b (36.9 mg, 62%) as yellow oil. 1 H NMR (400 MHz, CDCl3): δ 7.60 -7.57 (m, 2H), 7.39 -7.35 (m, 3H), 7.13 -7.07 (m, 2H), 7.02 -6.99 (m, 2H), 6 3c: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1c (39.8 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 3 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3c (42.9 mg, 72%) as yellow oil. 1  3d: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1d (48.2 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3d (51. 4  3e: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1e (48.2 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 3 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3e (62.8 mg, 87%) as yellow oil. 1  3f: A dried screw-vial seal tube was charged with CuI (3.8 mg, 0.01 mmol, 10 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1f (47 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3f (71.7 mg, 52%) as yellow oil. 1  3g: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1g (52.2 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 3.5 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3g (45.5 mg, 63%) as yellow oil. 1  3h: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1h (40.6 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 3 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3h (41.9 mg, 69%) as yellow oil. 1  3i: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1i (40.6 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3i (46.6 mg, 77%) as yellow oil. 1  3j: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1j (43.9 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 3.5 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3j ( 3k: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1k (43.9 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3k ( 3l: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1l (52.8 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3l (37.8 mg, 52%) as yellow oil. 1  S17 3m: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1m (33 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3m (39.8 mg, 75%) as slightly yellow oil. 3n: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1n (45 .4 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3n (43 mg, 66%) as colorless oil. 1  3o: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1o (38.6 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3o (44.7 mg, 76%) as yellow oil.  3p: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1p (38.2 mg, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3p (38.6 mg, 66%) as colorless oil. 1  3q: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1q (33.0 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3q (33. 3  3r: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1r (29.8 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3r (34.1 mg, 69%) as colorless oil.  3s: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1s (39.9 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 3.5 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3s (57.4 mg, 96%) as slightly yellow oil. 1  3t: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1t (30.6 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 3.5 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE/Et2O = 97:3) to obtain the desired product 3t (41.5 mg, 82%) as colorless oil. 1  3u: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, and 1u (39.0 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE/Et2O = 98:2) to obtain the desired product 3u (56.8 mg, 96%) as slightly yellow oil. 1  3v: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, and 1v (45.8 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE/Et2O = 98:2) to obtain the desired product  3w: A dried screw-vial seal tube was charged with CuI (3.8 mg, 0.01 mmol, 10 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1w (36.2 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 3.5 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3w (21.2 mg, 38%) as slightly yellow oil. 1  3x: A dried screw-vial seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the tube was cooled to -10 o C, 1x (37.8 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 3 hours at -10 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3x (25.9 mg, 45%) as yellow oil.

The results of reactions between different silylboronates with 1a.
Procedures for the reaction between 1a and silylboronate A: E: A dried seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then 1a (37.0 mg, 0.2 mmol, 1.0 equiv) and Et3Si-Bpin (96.9 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 12 hours at 30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 S23 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by preparative thin-layer chromatography (PTLC) (eluent: distilled PE) to obtain the desired product E (9.1 mg, 17%) as slightly yellow oil. 1  Procedures for the reaction between 1a and silylboronate C: G: A dried seal tube was charged with CuI (1.9 mg, 0.01 mmol, 5 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, dry Et3N (40.5 mg, 0.4 mmol, 2.0 equiv), dry DCE (1.0 mL) and dry MeOH (0.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then 1a (37.0 mg, 0.2 mmol, 1.0 equiv) and MePh2Si-Bpin (129.7 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 12 hours at 30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by preparative thin-layer chromatography (PTLC) (eluent: distilled PE) to obtain the desired product G (11.7 mg, 18%) as yellow oil. 1

General Procedures for the Synthesis of Enantioenriched Silyl-substituted Allenes (GP3)
(S)-3c: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol%) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1c (39.8 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which S24 was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3c (36.8 mg, 62%) as yellow oil.
(S)-3a: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol%) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1a (37 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3a (33.2 mg, 56%) as yellow oil. (S)-3b: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol%) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1b (39.8 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4.5 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3b (48.2 mg, 81%) as yellow oil. (S)-3d: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol , 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol%) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1d (48.2 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 7 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3d (35.4 mg, 52%) as yellow oil.
(S)-3e: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1e (48.2 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 15 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3e (47.7 mg, 70%) as yellow oil.
(S)-3f: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1f (47.0 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 15 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3f (41.5 mg, 62%) as yellow oil. (S)-3h: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1h (40.6 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 10 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3h (29 mg, 48%) as yellow oil.
(S)-3i: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1i (40.6 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3i (33.3 mg, 55%) as yellow oil.
(S)-3k: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1k (43.9 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3k (42.4 mg, 66%) as yellow oil.
(S)-3l: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1l (52.8 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 15 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3l (45.3 mg, 62%) as yellow oil.
(S)-3m: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1m (33.0 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3m (45.9 mg, 87%) as slightly yellow oil.
(S)-3n: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1n (45.4 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE/Et2O = 98:2) to obtain the desired product (S)-3n (57.6 mg, 88%) as colorless oil.
(S)-3p: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol , 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, and 1p (38.2 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product (S)-3p (51.7 mg, 89%) as slightly yellow oil.
(S)-3s: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1s (39.9 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE/Et2O = 98:2) to obtain the desired product (S)-3s (40.8 mg, 68%) as colorless oil.
(S)-3t: A dried screw-vial seal tube was charged with CuF2 (2.0 mg, 0.02 mmol, 10 mol %) and ligand L5 (19.5 mg, 0.04 mmol, 20 mol %) in glove box, then moved it out of the glove box. The tube was equipped with an argon balloon, TMP (56.5 mg, 0.4 mmol, 2.0 equiv) and extra dry MeOH (1.0 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white solution. Then the tube was cooled to -30 o C, 1t (30.6 mg, 0.2 mmol, 1.0 equiv) and PhMe2Si-Bpin (105 mg, 0.4 mmol, 2.0 equiv) were added in sequence via syringe. It was continued to stir for 4 hours at -30 o C. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE/Et2O = 99:1) to obtain the desired product (S)-3t (44.5 mg, 88%) as slightly yellow oil. The system was warmed to 0 o C, and stirred 10 hours at this temperature. The tube was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 6 (59 mg, 74 %) as yellow oil. The product 10 can't be separated by HPLC, the subsequent TiCl4-mediated addition of 10 to aldehyde afforded the homopropargylic alcohol. At beginning, we tried the 4-methylbenzaldehyde and isobutyraldehyde to react with the racemic allenylsilane 10 in the presence of different Lewis acids. Finally, it was found that only TiCl4 could afford the desired products with excellent dr ratios albeit in low yields. Therefore, we consider that a highly reactive reactant possibly could favor a better yield of the desired product via a rapid nucleophilic addition process. Then the pentafluorobenzaldehyde was tested to react with the racemic allenylsilane 10 and enantioenriched allenylsilane 10 respectively. In both cases, the desired products were obtained in good yields and with excellent distereoselectivities. And S34 the chirality of the enantioenriched allenylsilane 10 was also well transformed during the synthesis of homoallylic alcohol product 11. The detailed results are shown as below: The enantiomeric excess of 11 was determined by chiral HPLC analysis on Chiralcel OJ column. Conditions: hexane/isopropanol = 99:1, flow rate = 0.5 mL/min, UV-Vis detection at λ = 220 nm, tR1 = 7.3 min (major), tR2 = 7.9 min (minor), 20 o C, ee = 72%.

Gram-scaled Synthesis of Racemic Silyl-substituted Allenes.
A dried screw-vial flask was charged with CuI (47.5 mg, 0.25 mmol) in glove box, then S35 moved it out of the glove box. The flask was equipped with an argon balloon, dry Et3N (1.0 g, 10.0 mmol), dry DCE (25.0 mL) and dry MeOH (12.5 mL) were added into it. The mixture was stirred for 1 hour at room temperature to form a white suspension. Then the flask was cooled to -10 o C, 1s (1.0 g, 5.0 mmol) and PhMe2Si-Bpin (2.63 g, 10.0 mmol) were added in sequence via syringe. It was continued to stir for 3.5 hours at -10 o C. The flask was opened quickly at room temperature, the final solution was filtered through celite using CH2Cl2 (30 mL) under air. The filtrate was concentrated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: PE) to obtain the desired product 3s (1.24 g, 83%) as pale yellow oil.
9 Determination of the Absolute Configuration of Compound (S)-3p.
Step 1: In an oven-dried 35 mL screw-vial seal tube equipped with a stirring bar, 8 (78.1 mg, 0.2 mmol) was dissolved in 2 mL of dry THF under argon atmosphere. The solution was added LiAlH4 (15.2 mg, 0.4 mmol) in four batches at 20 °C. The final solution was continued to stir for 3 hours at room temperature (20 °C). Then the reaction was quenched with water and excess amount of saturated potassium sodium tartrate was introduced, and the solution was stirred for 1 hour at room temperature (20 °C). The final solution was extracted with ethyl acetate (4 x 15 mL), and the combined organic layers were washed with saturated brine (5 mL) and dried over anhydrous Na2SO4. The filtrate was concentrated under vacuum to afford the crude product which was purified through flash column chromatography (Eluent: PE/EA = 90:10) to furnish the related product 12 (56.6 mg, 78%, 80% ee) as yellow oil.
Step 2: A dried screw-vial seal tube equipped with an argon balloon, 12 (72.5 mg, 0.2 mmol) and dry DCM (1.0 mL) were introduced. PCC (86.2 mg, 0.4 mmol) was added into it, the mixture was continued to stir for 2 hours at 25 o C. Then the final solution was filtered through celite using CH2Cl2 (30 mL) and the solvent was evaporated under reduced pressure to afford the crude product, which was purified by flash column chromatography on silica gel (eluent: