SIRT1 and non-small cell lung carcinoma: Compound 13d, the n‐butyl substituted derivative of 13c, is a low‐micromolar SIRT2 inhibitor selective over SIRT1 [IC50(SIRT1) = 16.9 μM, IC50(SIRT2) = 1.0 μM] capable of increasing the levels of acetyl α‐tubulin in NSCLC cell line H1299.331