Bile acids. LXXI. A new synthesis of (25R)‐3α, 7α‐dihydroxy‐[5α,6α‐³H₂]‐5α‐cholestan‐26‐oic acid (1)

Abstract

with Jones reagent provided 3.7-dioxo and 3-oxo-[5a,6a-3H~]-5a-cholestanoic acids which were separated. Stereospecific reduction of the 3.7-dioxo methyl ester with K-Selectride followed by alkaline hydrolysis afforded (25R)-3a,7a-dihydroxy-[ 5a,6a-'Hz J-5a-cholestan-26-oic acid.

Formal Synthesis of Squalamine from Desmosterol

“…Hydrogenation of compound 7 using Adams catalyst under an atmospheric pressure of hydrogen resulted in the formation of 7-keto compound 9 in 66% yield together with 7b-alcohol 8 in 23% yield under the influence of steric hindrance of the C-19 methyl group. 25,26) The latter was easily transformed into the former by PCC oxidation in 92% yield. After hydrolysis of the 3-O-acetyl group of compound 9, stereoselective reduction of the 7-keto group resulted in the formation of the desired 7a-alcohol 11 in 77% yield using K-selectride, the stereoselectivity of which was reported by Göndös and Orr.…”