Structure determination of diacholestanes. Their geochemical significance

Abstract Six isomeric rearranged cholestanes (diacholestanes) were synthesized and their structures completely determined by X-ray diffraction and NMR. Four of them, the (20 R + 20 S ) 13β(H), 17α(H)- and (20 R + 20 S ) 13α(H), 17β(H)-diacholestanes are identical with the major C-27 geodiacholestanes. The two other isomers, the (20 R ) 13α(H), 17α(H)- and 13β(H), 17β(H)-diacholestanes, have not yet been found in geological samples.