1-Butanol → 5alpha-Hydroxy-6beta-(3-propylamino)-cholest-7-en-3beta-ol

Beteiligte Stoffe

Reaktionsschritte

5,6α-epoxicholest-7-en-3β-ol (8.9 g, 22.1 mmol, 1 eq) and tryptamine (7.1 g, 44.1 mmol, 2 eq) were charged in a round-bottomed flask equipped with a magnetic stirrer bar. 1-Butanol (70 ml, 5 vol) was added and the mixture heated to reflux for 40 h. The reaction mixture was cooled at r.t., diluted with methyl-tertbutyl-ether (5 vol) and washed with water (5 vol) and with brine (5 vol). The organic layer was passed through a silica pad (40 g) eluted with methyl-tertbutyl-ether (3 vol) then 10% Methanol/ethyl acetate (60 vol). Fractions of interest were pooled and the solvent was removed under reduced pressure to give 5α-Hydroxy-6β-(3-propylamino)-cholest-7-en-3β-ol as a white solid (7.3 g, 59%). In same conditions, use of ethanol as solvent (40 vol) and Ca(OTf)2 as catalyst gave a 23% yield.

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