Synthesis of 24-heteroatom-substituted cholestanols

A Concise Account of Various Approaches for Stereoselective Construction of the C-20(H) Stereogenic Center in Steroid Side Chain

“…Catalytic hydrogenation of 73 with Rh–Al 2 O 3 gave 74 in 90% yield as a mixture of C-20 epimers (20 S :20 R 4:3) . In the same report, catalytic hydrogenation of 75 with Pd/C gave a mixture of C-20 hydrogenated product 76 in 56% yield (mixture at C-20) and deoxygenated product 77 in 34% yield (also mixture at C-20) (Scheme ).…”

“…Various stereoselective methods used for generation of both the C-20 natural and unnatural epimers (Figure 1) are discussed. 51 In the same report, 51 catalytic hydrogenation of 75 with Pd/C gave a mixture of C-20 hydrogenated product 76 in 56% yield (mixture at C-20) and deoxygenated product 77 in 34% yield (also mixture at C-20) (Scheme 4).…”