The production of ( R )‐2‐hydroxy‐1‐phenyl‐propan‐1‐one derivatives by benzaldehyde lyase from Pseudomonas fluorescens in a continuously operated membrane reactor

Benzaldehyde lyase (BAL; E.C. 4.1.2.38) from Pseudomonas fluorescens Biovar I catalyzes the reversible formation of benzoins from aromatic aldehydes, and, moreover, the coupling of aromatic with aliphatic aldehydes yielding derivatives of ( R )‐2‐hydroxy‐1‐phenyl‐ propan‐1‐one ( R )‐HPPs), which are important chiral building blocks. In this paper, we report on the development of a reactor system that allows the selective production of substituted ( R )‐HPP‐derivatives. The reaction systems yielding ( R )‐1‐(3‐chloro‐phenyl)‐2‐hydroxy‐ propan‐1‐one, ( R )‐2‐hydroxy‐3‐methoxy‐1‐(4‐methoxy‐phenyl)‐propan‐1‐one, and ( R )‐2‐hydroxy‐3,3‐dimethoxy‐1‐phenyl‐propan‐1‐one were investigated. A kinetic model optimized by batch experiments was developed, for the description of both batch and continuously operated reactors. This model was used to describe the HPP production in a continuously operated enzyme membrane reactor. The reactor type used combines the advantages of high conversion and excellent selectivity with high space‐time yields and total turnover numbers of up to ttn  = 43,000. Products were obtained in high yield on a gram scale. Biotechnol. Bioeng. 2007;96:835–843. © 2006 Wiley Periodicals, Inc.