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Chemoselective Catalysis with Organosoluble Lewis Acidic Polyoxotungstates
Author(s) -
Dupré Nathalie,
Rémy Pauline,
Micoine Kévin,
Boglio Cécile,
Thorimbert Serge,
Lacôte Emmanuel,
Hasenknopf Bernold,
Malacria Max
Publication year - 2010
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.201000411
Subject(s) - chemistry , catalysis , lewis acids and bases , pyridine , lewis acid catalysis , reactivity (psychology) , frustrated lewis pair , organic chemistry , polymer chemistry , mannich reaction , medicinal chemistry , medicine , alternative medicine , pathology
Abstract The preparation of new organosoluble Lewis acidic polyoxometalates (POMs) is reported. These complexes were prepared by the incorporation of Zr, Sc, and Y atoms into the corresponding monolacunary Dawson [P 2 W 17 O 61 ] 10− and Keggin [PW 11 O 39 ] 7− polyoxotungstates. The catalytic activity of these compounds was evaluated for CC bond formation in the Diels–Alder, Mannich, and Mukaiyama‐type reactions. Comparisons with previously described Lewis acidic POMs are reported. Competitive reactions between imines and aldehydes or between various imines demonstrated that fine tuning of the reactivity could be reached by varying the metal atom incorporated into the polyanionic framework. A series of experiments that employed pyridine derivatives allowed us to distinguish between the Lewis and induced Brønsted acidity of the POMs. These catalysts activate imines in a Lewis acidic way, whereas aldehydes are activated by indirect Brønsted catalysis.