ENPP2 and pulmonary fibrosis: The GBB-3CR (Table 1: reaction (1)) is a popular reaction in medicinal chemistry which was used in the discovery of tool compounds for the first bromodomain of human BRD422 and was instrumental in the development of the clinical autotaxin inhibitor Ziritaxesta® that is used for the treatment of idiopathic pulmonary fibrosis.23 A recent comprehensive review reveals that GBB-3CR is a versatile MCR variation of the Ugi reaction, which can be performed under a broad range of conditions.