Synthesis and Determination of Stereochemistry of Four Diastereoisomers at the C-24 and C-25 Positions of 3α, 7α, 12α, 24-Tetrahydroxy-5β-cholestan-26-oic Acid

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Four diastereoisomers at the C-24 and C-25 positions of 3α, 7α, 12α, 24-tetrahydroxy-5β-cholestan-26-oic acid (varanic acid) were synthesized in a stereochemically defined manner and also by a non-stereoselective route, followed by chromatographic separation. Their stereochemistry at the C-24 and C-25 positions was established on the basis of the known stereochemical course of the reactions employed for the synthesis, and ¹H and ¹³C-nuclear magnetic resonance spectroscopic data of these isomers. It is concluded from the present work that the previous stereochemical assignment for the (24R, 25S) and (24R, 25R) isomers must be revised.