Formation of C-C Bonds via Ruthenium-catalyzed Transfer Hydrogenation: Carbonyl Addition from the Alcohol or Aldehyde Oxidation Level

Under the conditions of ruthenium-catalyzed transfer hydrogenation employing isopropyl alcohol as terminal reductant, pi-unsaturated compounds (1,3-dienes, allenes, 1,3-enynes, and alkynes) reductively couple to aldehydes to furnish products of carbonyl addition. In the absence of isopropyl alcohol, pi-unsaturated compounds couple directly from the alcohol oxidation level to form identical products of carbonyl addition. Such "alcohol-unsaturate C-C couplings" enable carbonyl allylation propargylation and vinylation from the alcohol oxidation level in the absence of stoichiometric organometallic reagents or metallic reductants. Thus, direct catalytic C-H functionalization of alcohols at the carbinol carbon is achieved.