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Enantioselective Oxidation of Chiral Titanium Enolates Derived from Propiophenone by Dimethyldioxirane or 3‐Phenyl‐2‐phenylsulfonyloxazirdine
Author(s) -
Adam Waldemar,
Prechtl Frank
Publication year - 1994
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19941270415
Subject(s) - propiophenone , dimethyldioxirane , chemistry , stereoselectivity , enantioselective synthesis , ketone , enantiomer , titanium , medicinal chemistry , organic chemistry , catalysis
The stereoselective oxidation of the optically active titanium enolate complexes 2 of propiophenone by dimethyldioxirane ( 3 ) (as acetone solution) and 3‐Phenyl‐2‐phenylsulfonyloxaziridine ( 4 ) has been investigated. The chiral titanium enolates 2 were synthesized by the reaction of the lithium enolate of propiophenone and the respective optically active chlorotitanate complexes 1. For 3 as oxidant, the stereoselectivity of the α hydroxylation strongly depends on the substitution pattern at the central titanium atom and reached for the best case, namely 2e , an enantiomeric excess (ee) of 63%. Solvent and temperature exhibited only small effects on the stereoselectivity. Compound 4 as oxidant gave lower enantiomeric excesses than 3 .