SELECTIVE REDUCTION OF ALKYNES TO CIS-ALKENES BY HYDROMETALLATION USING 6

Article abstract of DOI:10.1016/S0040-4039(00)97371-4

Selective reduction of alkynes to the corresponding alkenes is reported using the stable, readily prepared copper(I) hydride reagent, <(Ph3P)CuH>6.Terminal alkynes are reduced at room temperature, unactivated internal alkynes react only at elevated temperature.Disubstituted alkynes with propargyl activation are also reduced, giving cis-olefins selectively.Protection of propargylic alcohol functionality is unnecessary, although fragmentation is sometimes competitive in sterically hindered cases.A tertiary propargyl acetate gave displacement to the allene exclusively.