Biocatalytic Approach for the Synthesis of Enantiopure Acebutolol as a β1-Selective Blocker

A new chemoenzymatic route is reported to synthesize acebutolol, a selective β1 adrenergic receptor blocking agent in enantiopure (R and S) forms. The enzymatic kinetic resolution strategy was used to synthesize enantiopure intermediates (R)‐ and (S)‐N‐(3‐acetyl‐4‐(3‐chloro‐2‐hydroxypropoxy)phenyl)butyramide from the corresponding racemic alcohols. The results showed that out of eleven commercially available lipase preparations, two enzyme preparations (Lipase A, Candida antarctica, CLEA [CAL CLEA] and Candida rugosa lipase, 62316 [CRL 62316]) act in enantioselective manner. Under optimized conditions the enantiomeric excess of both (R)‐ and (S)‐N‐(3‐acetyl‐4‐(3‐chloro‐2‐hydroxypropoxy)phenyl)butyramide were 99.9 and 96.8%, respectively. N‐alkylation of both the (R) and (S) intermediates with isopropylamine gave enantiomerically pure (R and S)‐ acebutolol with a yield 68 and 72%, respectively. This study suggests a high yielding, easy and environmentally green approach to synthesize enantiopure acebutolol. Chirality 27:382–391, 2015. © 2015 Wiley Periodicals, Inc.