α-Selective syn-Carbotrifluoromethylthiolation of Alkynes.

Trifluoromethylthiolative difunctionalization of alkynes typically proceeds in an anti-fashion delivering the SCF3 group in the β-position (anti-Markovnikov). Herein, we disclose a vicinal syn-arylation-trifluoromethylthiolation of alkynes enabling α-selective introduction of the SCF3 group (Markovnikov). The unique selectivity was achieved via a merge of Ni-catalyzed carbomagnesiation with a subsequent Cu-mediated trifluoromethylthiolation of the resulting vinyl-magnesium species. The former component of the sequential process determines both the regio- and stereoselectivity of the overall transformation.