title: Stereoselective synthesis of trisubstituted olefins by a directed allylic substitution strategy.
abstract: New methodology for the stereoselective synthesis of trisubstituted olefins is presented. The use of ortho-diphenylphosphanyl benzoate (o-DPPB) as a directing leaving group for copper-mediated allylic substitution with Grignard reagents allowed for the stereoselective construction of a wide range of E olefins, without the need for an adjacent electron-withdrawing group. Our modular three-step approach toward trisubstituted alkenes commenced with geminal α-methylene aldehydes. Addition of an organometallic reagent and introduction of the o-DPPB group by esterification was followed by the o-DPPB-directed copper-mediated allylic substitution with a Grignard reagent to furnish stereodefined trisubstituted olefins. Additionally, incorporation of a stereocenter from the chiral pool allowed the preparation of an enantiomerically pure olefin that bore three alkyl substituents in high E/Z selectivity.
authors: Institut für Organische Chemie und Biochemie, Freiburg Institute for Advanced Studies (FRIAS), Universität Freiburg, Albertstr. 21, Germany.
authors: Yvonne
authors: Y
authors: Schmidt
authors: Bernhard
authors: B
authors: Breit
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D000498:Allyl Compounds / Q000737:chemistry*; D001565:Benzoates / Q000138:chemical synthesis* / Q000737:chemistry*; D001713:Biphenyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D015394:Molecular Structure; D009943:Organophosphorus Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D000498:Allyl Compounds; D001565:Benzoates; D001713:Biphenyl Compounds; D009943:Organophosphorus Compounds; C544846:o-diphenylphosphanylbenzoyl