Chen An-qi
2007
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Journal
Journal of Xiamen University
Abstract
Polyhydroxy cyclohexyl-β-amino acids and their derivatives have important pharmaceutical,biological and synthetic applications.This paper describes the determination of the absolute configuration of the key lactone intermediate(2),obtained by cinchonine mediated desymmetrization of cis-1,2,3,6-tetrahydrophthalic anhydride(1),and its application in the stereoselective synthesis of a polyhydroxy cyclohexyl-β-amino acid derivative(6).In order to determine the absolute stereochemistry of the lactone intermediate,compound(2)was treated with K2CO3 in benzyl alcohol to provide the ring opened product(3) which was converted to its C4 p-bromobenzoate(4) whose absolute stereochemistry was determined as(1S,4S,6R) by single crystal X-ray diffraction analysis therefore proved the configuration of the lactone intermediate(2).Catalytic dihydroxylation of the lactone intermediate(2) with OsO4 and NMO provided the desired dihydroxy compound(5) which underwent alcoholisms with benzyl alcohol in the presence of K2CO3,providing the target compound,(1R,2S,3R,4S,6R)-2,3,4-trihydroxy-cyclohexyl-β-amino acid derivatives(6),in 2 steps in 45% overall yield in a highly stereoselective manner,which highlighted the usefulness of the lactone intermediate(2) in the asymmetric synthesis of polyhydroxy cyclohexyl-β-amino acid derivatives.