Efficient Synthesis of a Chiral Precursor for Angiotensin-Converting Enzyme (ACE) Inhibitors in High Space-Time Yield by a New Reductase without External Cofactors

A new reductase, CgKR2, with the ability to reduce ethyl 2-oxo-4-phenylbutyrate (OPBE) to ethyl (R)-2-hydroxy-4-phenylbutyrate ((R)-HPBE), an important chiral precursor for angiotensin-converting enzyme (ACE) inhibitors, was discovered. For the first time, (R)-HPBE with >99% ee was produced via bioreduction of OPBE at 1 M without external addition of cofactors. The space-time yield (700 g·L(-1)·d(-1)) was 27 times higher than the highest record.