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Substrate‐Directed Diastereoselective Hydroformylations, 1. Substrate‐Directed Diastereoselective Hydroformylation of Methallylic Alcohols – Development of an Efficient Catalyst‐Directing Group for Rhodium‐Catalyzed Hydroformylation
Author(s) -
Breit Bernhard
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970907
Subject(s) - hydroformylation , stereocenter , chemistry , catalysis , rhodium , substrate (aquarium) , steric effects , stereoselectivity , hydrolysis , substituent , organic chemistry , medicinal chemistry , enantioselective synthesis , oceanography , geology
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 .