Catalytic hydrogenation with frustrated Lewis pairs: selectivity achieved by size-exclusion design of Lewis acids.
Chemistry
; 18(2): 574-85, 2012 Jan 09.
Article
em En
| MEDLINE
| ID: mdl-22161804
ABSTRACT
Catalytic hydrogenation that utilizes frustrated Lewis pair (FLP) catalysts is a subject of growing interest because such catalysts offer a unique opportunity for the development of transition-metal-free hydrogenations. The aim of our recent efforts is to further increase the functional-group tolerance and chemoselectivity of FLP catalysts by means of size-exclusion catalyst design. Given that hydrogen molecule is the smallest molecule, our modified Lewis acids feature a highly shielded boron center that still allows the cleavage of the hydrogen but avoids undesirable FLP reactivity by simple physical constraint. As a result, greater latitude in substrate scope can be achieved, as exemplified by the chemoselective reduction of α,ß-unsaturated imines, ketones, and quinolines. In addition to synthetic aspects, detailed NMR spectroscopic, DFT, and (2)H isotopic labeling studies were performed to gain further mechanistic insight into FLP hydrogenation.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ácidos de Lewis
Idioma:
En
Revista:
Chemistry
Ano de publicação:
2012
Tipo de documento:
Article