HALOCYCLIZATIONS AND CYCLOISOMERIZATIONS OF BISARYL 1,6-DIYNES

摘要

N-Sulfonamide tethered bisaryl 1,6-diynes underwent cyclization in the presence of Ga(III) trihalide to give mixtures of halocyclization (HC) and Friedel-Crafts (FC) cycloisomerization products. The ratio of products was found to be dependent on the identity of the halide and diyne substrate. In contrast, under Bronsted acid conditions only Friedel-Crafts cycloisomerization products were obtained. The regiochemical preference of the cyclization under Bronsted acid catalysis was reversed under Lewis acid catalysis. Herein, we report our efforts to understand and make use of this disparity to access a range of vinyl halides and indenopyridines from readily accessible 1,6-diynes.