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Enantio‐ and regioselectivity in the epoxide‐hydrolase‐catalyzed ring opening of aliphatic oxiranes: Part II: Dialkyl‐ and trialkylsubstituted oxiranes
Author(s) -
Wistuba D.,
Träger O.,
Schurig V.
Publication year - 1992
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.530040310
Subject(s) - chemistry , regioselectivity , epoxide , substituent , stereochemistry , epoxide hydrolase , nucleophile , enantiomer , hydrolysis , alkyl , ring (chemistry) , catalysis , organic chemistry , enzyme , microsome
Abstract The extent of substrate enantioselectivity and regioselectivity of a series of aliphatic 2,3‐dialkyl‐ and trialkylsubstituted oxiranes in their in vitro epoxide‐hydrolase‐catalyzed hydrolysis depends on the size of the alkyl residues and on the substitution pattern of the oxirane ring. The enzyme‐catalyzed hydrolysis of cis ‐oxiranes, containing at least one methyl substituent, shows complete or nearly complete substrate enantioselectivity and regioselectivity with nucleophilic attack by water occurring with inversion of configuration at the methylsubstituted ring carbon atom of (S) ‐configuration. In the hydrolysis of the isomeric trans ‐oxiranes, both enantiomers are metabolized with a higher rate for the (2S;3S) ‐enantiomer. The conversion of trimethyloxirane occurs with high substrate enantioselectivity in favor of the (S) ‐enantiomer and with complete regioselectivity at the monomethylsubstituted ring carbon atom. The differentiation of the enantiotopic ring carbon atoms ( product enantioselectivity ) in the smallest aliphatic meso ‐oxirane, cis ‐2,3‐dimethyloxirane, leads to (2R;3R)‐butane‐2,3‐diol with ee = 86%. cis ‐2‐Ethyl‐3‐propyloxirane, possessing alkyl residues larger than methyl, represents an extremely poor substrate in the epoxide‐hydrolase‐catalyzed hydrolysis process. © 1992 Wiley‐Liss, Inc.