Response surface methodology as an optimization strategy for the light-controlled asymmetric hydrogenation of 4-(trimethylsilyl)-3-butyn-2-one by photosynthetic bacteria

Enantiomerically pure (S)-4-(trimethylsilyl)-3-butyn-2-ol {(S)-TMSBL} is a key intermediate for the synthesis of many biologically and structurally interesting compounds and pharmaceuticals. Herein we propose a new light-controlled asymmetric hydrogenation of 4-(trimethylsilyl)-3-butyn-2-one (TMSBO) to enantiopure (S)-TMSBL by photosynthetic bacteria Rhodobacter sphaeroides, which is a newly isolated photosynthetic bacteria strain that has the capacity to capture light energy and to generate NADPH through photosynthetic electron-transfer reactions; no oxygen or other metabolic intermediates were used. Response Surface Methodology (RSM) was used to investigate the effects of substrate concentration, pH, and temperature on the reaction yield. A 33 factorial design was performed to optimize the production of (S)-TMSBL. The optimum conditions were: cell concentration (200 g/L), shaking speed (140 rpm), pH (6.9), substrate concentration (14.4 mmol/L), and temperature (33.6 °C). This optimization strategy led to an increase of the yield from 88.9% to 94.5%.