Directing abilities of alcohol-derived functional groups in the hydroformylation of olefins.
The hydroformylation of allylic and homoallylic alcohols and their derivatives using cationic and neutral rhodium complexes has been examined. The highest diastereoselectivity (87:13) was observed in the reaction of 1-methoxymethoxy-2-methylenecyclohexane. Higher yields and similar selectivities were obtained in the reaction of the TBDMS-protected alcohol. The major diastereomer results from hydroformylation syn to the functional group, which would suggest a directing effect. However, hydroformylation of 3-methylene-1-cyclohexanol derivatives occurs on the face opposite to the directing group in the major isomer. These data, in addition to the results of hydroformylation of 1-methyl-2-methylenecyclohexane, suggest that inherent conformational preferences are of significant importance in determining the product distribution and that the directing power of simple alcohols and their derivatives is moderate at best under the conditions examined in this study.
Ren
Li
L
Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 6E2.
Crudden
Cathleen M
CM