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Stereoselective Synthesis of Trisubstituted Olefins by a Directed Allylic Substitution Strategy
Author(s) -
Schmidt Yvonne,
Breit Bernhard
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201100843
Subject(s) - stereoselectivity , allylic rearrangement , stereocenter , chemistry , reagent , olefin fiber , methylene , alkyl , geminal , organic chemistry , medicinal chemistry , stereochemistry , enantioselective synthesis , catalysis
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.