Stereoselective synthesis of trisubstituted olefins by a directed allylic substitution strategy |
| |
Authors: | Schmidt Yvonne Breit Bernhard |
| |
Institution: | Institut für Organische Chemie und Biochemie, Freiburg Institute for Advanced Studies (FRIAS), Universit?t Freiburg, Albertstr. 21 (Germany), Fax: (+49)?761‐203‐8715 |
| |
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. |
| |
Keywords: | allylation directed reactions organocopper reagents synthetic methods trisubstituted olefins |
本文献已被 PubMed 等数据库收录! |