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Enantioselective Ring Opening of Epoxides with Silicon Tetrachloride in the Presence of a Chiral Lewis Base: Mechanism Studies
Author(s) -
Denmark Scott E.,
Barsanti Paul A.,
Beutner Gregory L.,
Wilson Tyler W.
Publication year - 2007
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200600551
Subject(s) - chemistry , enantioselective synthesis , silicon tetrachloride , catalysis , reagent , lewis acids and bases , organic chemistry , ring (chemistry) , stoichiometry , epoxide , transition state , silicon , medicinal chemistry
The enantioselective ring opening of meso ‐epoxides (from both cyclic and acyclic olefins) with silicon tetrachloride under catalysis by chiral phosphoramides affords enantiomerically enriched chlorohydrins in excellent yields. Experiments designed to elucidate the mechanistic foundation and origins of enantioselectivity are described. From studies on the loading and stoichiometry of the reagent (SiCl 4 ) and the catalyst [( R )‐ 1 ] it was established that only one chloride per SiCl 4 is delivered and that the nature of reactive species does not change over the course of the reaction. Kinetic studies together with asymmetric amplification experiments have suggested that more than one catalyst molecule may be bound to SiCl 4 in the stereochemistry‐determining transition structure.