Application of rational enzyme engineering in a new route to etonogestrel and levonorgestrel: carbonyl reductase bioreduction of ethyl secodione

We combine the selection and engineering of a carbonyl reductase enzyme with process development, to enable efficient and economically viable bioreduction of ethyl secodione to (13 R ,17 S )-secol, the key chirality introducing intermediate en route to contraceptives etonogestrel and levonorgestrel.