title: Gold(I)-catalyzed regiodivergent rearrangements: 1,2- and 1,2'-alkyl migration in skipped alkynyl ketones.
abstract: A series of 2-alkynyl carbonyl compounds that contain a cyclopentene ring or a heterocycle can be transformed into various fused dihydrobenzofurans and tetrahydrofuro[2,3-c]pyridines by means of a 1,2-alkyl migration process. Both of these reactions proceed with excellent regioselectivity and stereospecificity when using a cationic gold(I) catalyst. Treatment of 4-styrylcyclopent-1-enecarboxylates under different conditions affords a range of highly functionalized dihydrobenzofurans and dihydroisobenzofurans. A divergence in product selectivity, which depends on the anion of the silver salts used, was observed. Interestingly, ring-fused tetrahydroquinolines undergo only 1,2'-alkyl migration reaction by means of a C-C cleavage/cyclization sequence to provide tetrahydroazepine derivatives. Mechanistic studies suggest that the gold complexes catalyze 1,2-alkyl migration reactions through a concerted reaction pathway and 1,2'-alkyl migration reactions through a stepwise reaction pathway.
authors.affiliation: Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663 N. Zhongshan Road, Shanghai 200062, PR China.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Li
authors.forename: Yuying
authors.initials: Y
authors.lastname: Li
authors.forename: Guanghua
authors.initials: G
authors.lastname: Zhou
authors.forename: Xiangshu
authors.initials: X
authors.lastname: Wu
authors.forename: Junliang
authors.initials: J
authors.lastname: Zhang