title: Optically active seleninate esters: isolation, absolute configuration, racemization mechanism, and transformation into chiral selenoxide.
abstract: Optically active seleninate esters were obtained for the first time by chromatographic resolution on an optically active column. The absolute configurations of the optically active seleninate esters were determined by comparing their chiroptical properties with those of two analogous sulfinate esters, the absolute configuration of one of which is known and that of the other was determined by X-ray crystallographic analysis. The optically active seleninate esters were found to racemize in solution. Kinetic studies of the racemization, the oxygen exchange reaction with H(2)(18)O, and theoretical studies clarified that the racemization of the optically active seleninate esters in solution proceeded via an achiral hypervalent selenurane intermediate that was formed by the reaction with water. The reaction of the optically active seleninate ester and the sulfinate ester having bulky substituents with Grignard reagents was found to proceed with the retention of stereochemistry to give an optically active selenoxide and sulfoxides, respectively.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minami-ohsawa, Hachioji, Tokyo 192-0397, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Toshio
authors.initials: T
authors.lastname: Shimizu
authors.forename: Kazunori
authors.initials: K
authors.lastname: Hirabayashi
authors.forename: Fujiko
authors.initials: F
authors.lastname: Iwasaki
authors.forename: Mikio
authors.initials: M
authors.lastname: Yamasaki
authors.forename: Nobumasa
authors.initials: N
authors.lastname: Kamigata