Enantioselective benzoylation of racemic amines using chiral benzimidazolide as a benzoylating agent

Enantioselective acylation/kinetic resolution of racemic amines has been achieved by using a chiral benzimidazolide, namely, (S)-1-benzoyl-2-(α-acetoxyethyl)benzimidazole 2. This nonenzymatic acylating reagent requires mild reaction conditions and proceeds with good enantioselectivity.

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(S)-N-Benzoyl-1-phenylethylamineC15H15NOEe = 89.9%[α]D19=-17.9 (c 1, CHCl3)Source of chirality: kinetic resolutionAbsolute configuration: (S)

(S)-N-Benzoyl-3-methyl-2-butylamineC12H17NOEe = 82.8%[α]D19=+12.4 (c 1, CHCl3)Source of chirality: kinetic resolutionAbsolute configuration: (S)

(S)-N-Benzoyl-2-heptylamineC14H21NOEe = 83.2%[α]D19=+14.6 (c 1, CHCl3)Source of chirality: kinetic resolutionAbsolute configuration: (S)

(S)-N-Benzoyl-2-butylamineC11H15NOEe = 83.3%[α]D19=+12.5 (c 1, CHCl3)Source of chirality: kinetic resolutionAbsolute configuration: (S)