Catalytic 1,2-Dicyanation of Alkynes by Palladium(II) under Aerobic Conditions

A stereoselective 1,2-dicyanation of various alkynes in the presence of trimethylsilyl cyanide (TMSCN) by palladium(II) catalysis under aerobic conditions is investigated. This reaction includes two cyanation pathways, syn- and anti-cyanopalladation to alkynes that are activated by Pd(II). High syn-selectivity was observed in the reaction using terminal alkynes that have bulky substituents at a propargyl position and aliphatic internal alkynes. Furthermore, a dramatic acceleration was observed with substrates having an N-arenesulfonyl functionality at a propargyl position, this indicates that both sulfoxide and carbon-carbon triple bond act as Lewis bases to Pd(II).