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Highly Enantioselective Aza‐Baylis–Hillman Reactions Catalyzed by Chiral Thiourea Derivatives
Author(s) -
Raheem Izzat T.,
Jacobsen Eric N.
Publication year - 2005
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.200505230
Subject(s) - chemistry , dabco , enantioselective synthesis , thiourea , methyl acrylate , imine , catalysis , baylis–hillman reaction , acrylate , adduct , yield (engineering) , organic chemistry , combinatorial chemistry , materials science , monomer , copolymer , metallurgy , polymer
We report the discovery of asymmetric aza‐Baylis–Hillman (ABH) reactions of N‐p‐ nitrobenzenesulfonylimines with methyl acrylate catalyzed by chiral thiourea derivatives. A series of aromatic imines was found to undergo coupling with methyl acrylate with unprecedented levels of enantioselectivity (87–99% ee), albeit only in modest (25–49%) yields. A DABCO‐acrylate‐imine adduct was isolated as a key intermediate in the ABH reaction. We provide a mechanistic analysis based on the identity of this intermediate as well as kinetic investigations and isotope studies, and propose a rationale for the observed limitations in yield. Synthetic applications of the ABH products are also described.