ISSN:
1434-193X
Keywords:
Asymmetric synthesis
;
Catalysis
;
Hydroformylations
;
Rhodium compounds
;
Catalyst-directing groups
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Introducing ortho-diphenylphosphanyl benzoyl as a substrate bound catalyst directing group (CDG) allows an efficient substrate-directed diastereoselective hydroformylation of acyclic homomethallylic alcohols 5, making use of 1,3-asymmetric induction. The corresponding anti-aldehydes 10 were obtained as the major diastereomer in all cases, with diastereomer ratios of ca. 91:9 (anti:syn). Supporting evidence could be obtained for the ability of the o-DPPB group to act as a catalyst-directing group (CDG) via a reversible catalyst coordination. Finally, a model has been devised that rationalizes the origin of the 1,3-asymmetric induction. This model is based on a conformational analysis (NMR studies, MACROMODEL/MM3 calculations) of the homomethallylic substrates and indicates a relationship between the preferred substrate conformation and the experimentally determined stereoselectivities. In agreement with this model was the predicted significant improvement in stereoselectivity upon hydroformylation of the anti-homomethallylic alcohol derivative 15 (→ 21).
Type of Medium:
Electronic Resource
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