Cyclic (Alkyl)(amino)carbene Ligands Enable Cu-Catalyzed Markovnikov Protoboration and Protosilylation of Terminal Alkynes: A Versatile Portal to Functionalized Alkenes**

Regioselective hydrofunctionalization of alkynes represents a straightforward route to access alkenyl boronate and silane building blocks. In previously reported catalytic systems, high selectivity is achieved with a limited scope of substrates and/or reagents, with general solutions lacking. Herein, we describe a selective copper-catalyzed Markovnikov hydrofunctionalization of terminal alkynes that is facilitated by strongly donating cyclic (alkyl)(amino)carbene (CAAC) ligands. Using this method, both alkyl- and aryl-substituted alkynes are coupled with a variety of boryl and silyl reagents with high alpha-selectivity. The reaction is scalable, and the products are versatile intermediates that can participate in various downstream transformations. Preliminary mechanistic experiments shed light on the role of CAAC ligands in this process.

Automated summary

In this study, a selective copper-catalyzed Markovnikov hydrofunctionalization of terminal alkynes is described, facilitated by strongly donating cyclic (alkyl)(amino)carbene (CAAC) ligands. The reaction allows coupling of both alkyl- and aryl-substituted alkynes with a variety of boryl and silyl reagents with high alpha-selectivity. The versatile intermediates produced are scalable and can participate in various downstream transformations.