title: Catalytic asymmetric synthesis of acyclic arrays by tandem 1,4-addition-aldol reactions.
abstract: Herein, we report efficient acyclic stereocontrol in tandem 1,4-addition-aldol reactions triggered by catalytic asymmetric organometallic addition. Grignard reagents add to alpha,beta-unsaturated thioesters in a 1,4-fashion and the resulting magnesium enolates are trapped with aromatic or aliphatic aldehydes. The process provides a range of tandem products bearing three contiguous stereocenters with excellent control of relative and absolute stereochemistry. The various diastereomeric products have been fully characterized using single-crystal X-ray analysis and the origins of stereocontrol in this tandem protocol are discussed. The versatility and efficiency of this methodology are demonstrated in the first catalytic asymmetric synthesis of (-)-phaseolinic acid with 54% overall yield via a short and concise route.
authors.affiliation: Department of Organic & Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Gareth P
authors.initials: GP
authors.lastname: Howell
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Fletcher
authors.forename: Koen
authors.initials: K
authors.lastname: Geurts
authors.forename: Bjorn
authors.initials: B
authors.lastname: ter Horst
authors.forename: Ben L
authors.initials: BL
authors.lastname: Feringa