Organocatalytic 1,4-Addition Reaction of α,β-γ,δ-Diunsaturated Aldehydes versus 1,6-Addition Reaction

Among 1,4-addition and 1,6-addition reactions, 1,4-addition reaction is the main reaction mode in the Michael reaction of a,beta-?,d-diunsaturated aldehyde with several nucleophiles catalyzed by diphenylprolinol silyl ether via iminium ion intermediate. The 1,4-addition products, which possess excellent enantioselectivity and alkene moiety, are useful chiral building blocks. The ab initio calculation indicates that 1,4-addition reaction is preferable in terms of p-orbital coefficient and Mulliken/CHelpG atomic charge.