Mechanistic Dichotomy in the Asymmetric Allylation of Aldehydes with Allyltrichlorosilanes Catalyzed by Chiral Pyridine N-Oxides
Journal article, 2013
Detailed kinetic and computational investigation of the enantio- and diastereoselective allylation of aldehydes 1 with allyltrichlorosilanes 5, employing the pyridine N-oxides METHOX (9) and QUINOX (10) as chiral organocatalysts, indicate that the reaction can proceed through a dissociative (cationic) or associative (neutral) mechanism: METHOX apparently favors a pentacoordinate cationic transition state, while the less sterically demanding QUINOX is likely to operate via a hexacoordinate neutral complex. In both pathways, only one molecule of the catalyst is involved in the rate- and selectivity-determining step, which is supported by both experimental and computational data.
organocatalysis
allylsilanes
pyridine N-oxides
allylation
calculations
Author
Andrei V. Malkov
University of Glasgow
Loughborough University
Sigitas Stoncius
Vilnius University
University of Glasgow
Mark Bell
University of Dundee
University of Glasgow
Fabiomassimo Castelluzzo
University of Glasgow
Bayer SpA, Italy
Pedro Ramirez-Lopez
University of Seville
University of Glasgow
Lada Biedermannova
University of Glasgow
Czech Academy of Sciences
Vratislav Langer
Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry
Lubomir Rulisek
Czech Academy of Sciences
Pavel Kocovsky
Stockholm University
University of Glasgow
Chemistry - A European Journal
0947-6539 (ISSN) 1521-3765 (eISSN)
Vol. 19 28 9167-9185Subject Categories
Chemical Sciences
DOI
10.1002/chem.201203817