Acylation of β‐Amino Esters and Hydrolysis of β‐Amido Esters: Candida antarctica Lipase A as a Chemoselective Deprotection Catalyst

Abstract

AbstractN‐Acylation by lipase A from Candida antarctica (CAL‐A) in ethyl butanoate was applied to the kinetic resolution of tert‐butyl esters of 3‐amino‐3‐phenylpropanoic acid (E>100), 3‐amino‐4‐methylpentanoic acid (E>100) and 3‐aminobutanoic acid (E=60) on 1.0–2.0 m scale. With the N‐acylated resolution products, the exceptional ability of CAL‐A to hydrolyse amides and bulky tert‐butyl esters was then studied. In all N‐acylated tert‐butyl esters, chemoselectivity favoured the amide bond cleavage. The tert‐butyl ester bond was left intact with 3‐amino‐3‐phenylpropanoate, whereas with 3‐amino‐4‐methylpentanoate and 3‐aminobutanoate the CAL‐A‐catalysed hydrolysis of tert‐butyl ester followed the amide hydrolysis.