Benzoyl chloride → 3beta,25-Dibenzoyloxycholest-5-ene

Beteiligte Stoffe

Reaktionsschritte

Heat 2.9 gm. (7.2 mmole) of 25-hydroxycholesterol with 2.1 ml. (18 mmole) of benzoyl chloride in 30 ml. of pyridine at 70°-80° C. for 4 hours. Add an additional 1.4 ml. (12 mmole) of benzoyl chloride and continue heating at 75°-80° C. for 1 hour. Pour the reaction mixture into ice-water mixture (b 1:1, 500 gm.) Stir for 1 hour, separate the precipitate and wash with ice-water. Recrystalize from acetone. Dissolve the crude product (3.8 gm.) in methylene chloride-hexane (3:2, 40 ml.) and pass the solution through a silica gel column (120 gm.). Elute the column with 800 ml. methylene chloride-hexane (5:1) followed by 800 ml. methylene chloridehexane (10:1). Combine the fractions and concentrate to a residue. Recrystalize from acetone to obtain the pure product (3.32 gm., m.p. 130°-132° C.).

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