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Free keywords:
cascade reactions · C-H activation ·
directed evolution · enantioselectivity · P450 monooxygenase
Abstract:
Biocatalytic cascade reactions
using isolated stereoselective enzymes or whole cells in one-pot
processes lead to value-added chiral products in a single
workup. The concept has been restricted mainly to starting
materials and intermediate products that are accepted by the
respective wild-type enzymes. In the present study, we exploited
directed evolution as a means to create E. coli whole cells for
regio- and stereoselective cascade sequences that are not
possible using man-made catalysts. The approach is illustrated
using P450-BM3 in combination with appropriate alcohol
dehydrogenases as catalysts in either two-, three-, or four-step
cascade reactions starting from cyclohexane, cyclohexanol, or
cyclohexanone, respectively, leading to either (R,R)-, (S,S)-, or
meso-cyclohexane-1,2-diol. The one-pot conversion of cyclohexane
into (R)- or (S)-2-hydroxycyclohexanone in the
absence of ADH is also described.
