Substrate-directed diastereoselective hydroformylations, 1: Substrate-directed diastereoselective hydroformylation of methallylic alcohols - Development of an efficient catalyst-directing group for rhodium-catalyzed hydroformylation

Article abstract of DOI:10.1002/jlac.199719970907

The development of an efficient catalyst-directing group based on ortho-diphenylphosphanyl benzoate (o-DPPB) for the substrate-directed, diastereoselective hydroformylation of methallylic alcohols 5 is described. The hydroformylation of methallylic o-DPPB esters 9 provides the corresponding syn-aldehydes 10 with diastereoselectivities of up to 96:4. A specific steric demand of the substituent at the stereogenic center of the methallylic derivatives 9 was found to be necessary to achieve a high degree of stereoselectivity. Experiments have been performed that prove that the o-DPPB group acts as a catalyst-directing group by reversibly coordinating to the catalyst. The removal of the o-DPPB group was accomplished by means of alkaline hydrolysis, thereby furnishing the lactols 6. Oxidation of 6 provides the corresponding γ-lactones 7. VCH Verlagsgesellschaft mbH, 1997.