From 1,2-difunctionalisation to cyanide-transfer cascades - Pd-catalysed cyanosulfenylation of internal (oligo)alkynes

Internal alkynes substituted by aliphatic or aromatic moieties or by heteroatoms were converted into sulphur-substituted acrylonitrile derivatives. Key is the use of Pd catalysis, which allows the addition of aromatic and aliphatic thiocyanates in an intra- and intermolecular manner. Substrates with several alkyne units underwent further carbopalladation steps after the initial thiopalladation step, thus generating in a cascade-like fashion an oligoene unit with sulphur at one terminus and the cyano group at the other.

The intra- and intermolecular Pd-catalysed cyanosulfenylation of internal alkynes enables the formation of tetrasubstituted thioacrylonitriles and is extended to oligoyne systems leading to oligoenes and a cyanide transfer over four or six atoms.

Palladium-Catalyzed Cyanothiolation of Internal Alkynes Using Organic Disulfides and tert-Butyl Isocyanide

Despite the availability of selective synthetic approaches to multifunctionalized substituted olefins, the cyanothiolation of internal alkynes has been much less explored. Herein, we show that nonactivated internal alkynes can be successfully cyanothiolated with diaryl disulfides and tert-butyl isocyanide in the presence of a Pd catalyst (e.g., Pd(PPh₃)₄) with the release of isobutene and arenethiol to afford β-thiolated alkenyl cyanides in yields of 34-89%.