Synthesis of 3 beta-(5 '-D-ribityl)cholestane, a putative biological precursor for fossil 3-alkylsteranes

A putative biological precursor for the widespread class of sedimentary 3-a lkylsteranes was synthesised from cholestanone in a stepwise stereoselectiv e manner. This unusual cholestane derivative bearing a C-5 tetrol side chai n at carbon C-3 represents the equivalent of bacteriohopanetetrol and may p rove a useful tool in the search for such compounds in microorganisms. In a ddition, the synthetic protocol represents a general entry into the prepara tion of sterols with side chains at C-3. (C) 2000 Elsevier Science Ltd. All rights reserved.