Scheme 6.

syn-Diastereo- and enantioselective copper-catalyzed carbonyl propargylation via silane-mediated reductive coupling and hydrogen auto-transfer using enyne pronucleophiles.^a

^a(S,S)-Ph-BPE = 1,2-Bis[(2S,5S)-2,5-diphenylphospholano]ethane. Yields are of material isolated by silica gel chromatography. Enantioselectivities determined by stationary phase HPLC analysis.^aDM-SEGPHOS = 5,5′−bis-[di(3,5-xylyl)phosphino]-4,4′-bi-1,3-benzodioxole. SEGPHOS = 5,5′-bis-(diphenylphosphino)-4,4′-bi-1,3-benzodioxole. cod = cycloocta-1,5-diene. TIPS = triisopropylsilyl. Yields are of material isolated by silica gel chromatography. Enantioselectivities determined by stationary phase HPLC analysis.