Synthesis of 3β-(5′-d-ribityl)cholestane, a putative biological precursor for fossil 3-alkylsteranes

A putative biological precursor for the widespread class of sedimentary 3-alkylsteranes was synthesised from cholestanone in a stepwise stereoselective manner. This unusual cholestane derivative bearing a C5 tetrol side chain at carbon C-3 represents the equivalent of bacteriohopanetetrol and may prove a useful tool in the search for such compounds in microorganisms. In addition, the synthetic protocol represents a general entry into the preparation of sterols with side chains at C-3.