IMPROVED SYNTHESIS OF 3α,7α,12α,24ξ-TETRAHYDROXY-5β-CHOLESTAN-26-OIC ACID

Article abstract of DOI:10.1016/0039-128X(82)90140-4

This paper describes three simple and short methods for the conversion of cholic acid into cholylaldehyde with protected hydroxyl groups.The first method involves lithium aluminium hydride reduction of the tetrahydropyranyl ether of methyl cholate and oxidation of the resulting primary alcohol with pyridinium chlorochromate.The second method employs diborane for the reduction of the -COOH group to the -CH2OH group, while the third method involves the reduction of 3α,7α,12α-triformyloxy-5β-cholan-24-oic acid (as the acid chloride) directly into 3α,7α,12α-triformyloxy-5β-cholan-24-al with TMA-ferride (tetramethylammonium hydridoirontetracarbonyl).The aldehyde obtained by any of the above methods underwent smooth Reformatsky reaction with ethyl α-bromopropionate to yield 3α,7α,12α,24ξ-tetrahydroxy-5β-cholestan-26-oic acid.