Chemoenzymatic synthesis of boron-containing chiral amines and amides

The first application of lipases as catalysts to obtain optically active boron-containing amines and amides is described. We studied several reaction conditions to achieve the kinetic resolution of boron-containing amines via enantioselective acylation mediated by Candida antarctica lipase B (CAL-B). Excellent enantioselectivity (E >200) and high enantiomeric excess (up to >99%) of both the remaining amines and amides were obtained.

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(S)-1-(4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethanamineC14H22BNO2Ee = 83%[α]D21=-26.7 (c 1.0, CHCl3)Absolute configuration: (S)

(R)-N-(1-(4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl)acetamideC16H24BNO3Ee = >99%[α]D21=+84.6 (c 1.0, CHCl3)Absolute configuration: (R)

(S)-1-(3-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethanamineC14H22BNO2Ee = 78%[α]D21=-15.6 (c 0.96, CHCl3)Absolute configuration: (S)

(R)-N-(1-(3-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)ethyl)acetamideC16H24BNO3Ee = >99%[α]D21=+55.2 (c 1.04, CHCl3)Absolute configuration: (R)

(R)-N-(1-(4-Bromophenyl)ethyl)acetamideC10H12BrNOEe = >99%[α]D21=+72.2 (c 1.02, CHCl3)Absolute configuration: (R)

(R)-N-(1-(3-Bromophenyl)ethyl)acetamideC10H12BrNOEe = >99%[α]D21=+47.6 (c 1.05, CHCl3)Absolute configuration: (R)