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A high-yielding, stereoselective synthesis of scymnol 1 has been carried out in five steps starting from commercially available cholic acid 2. The synthesis was designed with the aim of eventual large-scale processing. Triformyloxycholic acid chloride 4 was treated with the magnesium enolate of diethyl malonate to afford the β-keto diester, diethyl 3α,7α,12α-triformyloxy-24-oxo-5β-cholestane-26,27-dioate 5. The key step in the synthesis was the stereoselective hydrogenation of β-keto diester 5 to give the corresponding β-hydroxy diester 6 using a BINAP ruthenium(ii) catalyst. Subsequent reduction of the diester moiety and deprotection of the hydroxyl groups afforded scymnol 1.

Steroids U 0300 A Scalable Stereoselective Synthesis of Scymnol. -(ADHIKARI, R.; CUNDY, D. J.; FRANCIS*, C. L.; GEBARA-COGHLAN, M.; KRYWULT, B.; LUBIN, C.; SIMPSON, G. W.; YANG, Q.; Aust.

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