Industrial Biotransformations

68
3 Retrosynthetic Biocatalysis
3.6
Ketones
O
R R'
O
R R'
R
O
O
OH
R R'
R'
alcohol dehydrogenase
lyase
lyase
lipases
OH
R R'
R
R
OH
R'
O
N
R R'
Ketones can be prepared from alcohols under cofactor-dependent oxidation [16]. Studies
on sec-alcohol oxidases have not been well reported in the literature. Some specific
ketones can be formed by cleavage of a-hydroxyl ketones (acyloins) [17]. Lipase-catalyzed
hydrolysis of dimethylhydrazones serves as a mild method for the deprotection of
ketones [18].
3.7
Epoxides
R
O
R'
epoxidase
lipase
halohydrin
epoxidase
Epoxides can be obtained by enzymatic oxidation of alkenes or dehydrohalogenation
of chloro-alcohols using halohydrin epoxidases [19]. Alternatively, epoxidation of alkenes
can be catalyzed indirectly by lipases with in situ formation of a peroxo acid from H 2O 2.
R
R
OH
N
R'
R'
O
Cl
R''