Abstract
(24R)-and (24S)-27-nor-5β-cholestane-3α, 7α, 12α, 24, 26-pentols were synthesized, starting from 3α, 7α, 12α-trihydroxy-5β-cholan-24-al, by means of the Reformatsky reaction with bromoacetate and subsequent lithium aluminum hydride reduction of the resulting (24R)-and (24S)-3α, 7α, 12α, 24-tetrahydroxy-27-nor-5β-cholestan-26-oates. The configurations at C-24 of the synthetic pentols were assigned by 13C-nuclear magnetic resonance spectroscopy. By direct comparison with a synthetic specimen, 5β-ranol, the major bile constituent of bullfrog, was shown to be (24R)-27-nor-5β-cholestane-3α, 7α, 12α, 24, 26-pentol. The availability of the 24S-epimer of 5β-ranol enabled us to ascertain the absence of this bile alcohol in the bullfrog bile.
