Hydroformylation catalysts containing chelating

The hydroformylation of ally and vinyl acetals yields some useful intermediates. Allyl acetate undergoes partial double bond migration prior to hydroformylation with a cobalt catalyst in the absence of phosphine (equation 20).2-5 Rhodium catalysts containing chelating phosphines are more selective to the linear aldehyde.31... 

Among the rhodium complexes, the catalyst containing the nonsymmetrical atropisomeric phosphine-phosphite chelating ligand (1) gave the best enantioselec-tivity (up to 92% ee) in the hydroformylation of the ibuprofen precursor 4-isobutyl-styrene [2] whereas the use of the bulky diphosphite ligand 2 resulted in a remarkable regioselectivity with a branched/normal ratio of 98.5/1.5 and somewhat lower optical yield (82% ee) [3]. 

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