Asymmetric Conversion of Arenechromium Complexes to Functionalized Cyclohexenones: Progress toward Defining an Optimum Chiral Auxiliary
作者:Anthony J. Pearson、Alexander V. Gontcharov
DOI:10.1021/jo971676o
日期:1998.1.1
the asymmetric synthesis of 5-substituted cyclohexenones via nucleophileaddition to (alkoxyarene)chromium tricarbonyl complexes is described. Diastereoselectivity during the nucleophileaddition step was achieved using alkoxy substituents derived from terpenoid substrates as chiralauxiliaries. Selectivities as high as 24:1 were obtained when 2-phenylisoborneol was used as the chiralauxiliary and
[GRAPHICS]The chiral auxiliary [(1R)-exo]-3-exo-(diphenylmethyl)borneol, synthesized from (1R)-(+)-camphor in three steps, was highly effective for the stereoselective hydrocoupling of its cinnamates by electroreduction. From the resulting hydrodimers, (3R,4R)-3,4-diaryladipic acid esters and (3R,4R)-3,4-diarylhexane-1,6-diols were synthesized in 87-95% ee.