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 α,β‐γ,δ‐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 π‐orbital coefficient and Mulliken/CHelpG atomic charge.