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Salen as a Chiral Activator: anti versus syn Switchable Diastereoselection in the Enantioselective Addition of Crotyl Bromide to Aromatic Aldehydes
Author(s) -
Bandini Marco,
Cozzi Pier Giorgio,
UmaniRonchi Achille
Publication year - 2000
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/1521-3773(20000703)39:13<2327::aid-anie2327>3.0.co;2-9
Subject(s) - bromide , enantioselective synthesis , reagent , chemistry , chromium , catalysis , combinatorial chemistry , organic chemistry
To be syn or to be anti ? This is an “open” matter! A good degree of syn simple diastereoselection (up to 83:17) and high enantioselectivity ( ee values up to 90 %) were obtained with the addition of crotyl bromide to aromatic aldehydes promoted by the [Cr(salen)]/Mn/Me 3 SiCl catalytic system (see scheme, path B). The remarkable degree of syn simple diastereoselection obtained with organochromium reagents can be explained by an open transition state in a chromium‐mediated process.