Asymmetric Synthesis of Isothiazoles through Cu Catalysis: Direct Catalytic Asymmetric Conjugate Addition of Allyl Cyanide to α,β‐Unsaturated Thioamides

Twice the catalyst: The simultaneous activation of an allyl cyanide (pronucleophile) and an α,β-unsaturated thioamide (electrophile) was achieved using a Cu-based soft Lewis acid/hard Brønsted base cooperative catalyst, thus resulting in the formation of enethioamides 1 in a highly enantio- and Z-selective manner (see scheme). The sequential Cu-catalyzed intramolecular cyclization gave rise to enantioenriched fused isothiazoles 2.