Chemical Conversion of Corticosteroids to 3α, 5α-Tetrahydro Derivatives. Synthesis of Allotetrahydro-11-deoxycortisol Glucuronides

抄録

A method for the conversion of 11-deoxycortisol into 3α-hydroxy-5α-compounds is described. The allotetrahydro-11-deoxycortisol monoacetates (8, 14), which are key intermediates in the preparation of the 3- or 21-glucuronide of allotetrahydro-11-deoxycortisol, were the target compounds. The preparation of 5α-dihydro-11-deoxycortisol 21-acetate (4) was carried out by hydrogenation of the 3-ethoxy-3, 5-diene (2), followed by acid hydrolysis. When the 21-tetrahydropyranyl ether (6) and 21-tert-butyldimethylsilyl ether (7) were treated with potassium tri-secbutylborohydride in tetrahydrofuran under mild conditions, selective reduction of the carbonyl group at C-3 took place, yielding the 3α-alcohols (9 and 10, respectively). Allotetrahydro-11-deoxycortisol 3-glucuronide (21) and allotetrahydro-11-deoxycortisol 21-glucuronide (23) were then prepared.