An easy access to enantio-enriched α-substituted aldehydes by carbolithiation of β-phenyl or β-silyl-α,β-ethylenic aldehydes, protected with the monolithioamide of a chiral diamine

Lithium amide derived from N,N,N′-trimethyl-1,2-diphenylethanediamine converts cinnamaldehyde to a lithium alkoxyamide which undergoes a regio- and stereoselective carbolithiation upon addition of various organolithiums. Subsequent hydrolysis or trapping with MeI delivers α-mono-, or α,β-disubstituted 3-phenylpropanals with e.e.s of 76–96%. Extension to a silylated α-enal is possible.