New Preparation and Controlled Alkaline Hydrolysis of 21-Bromo-20-ketopregnenes. A Facile Synthesis of Deoxycorticoids

Article abstract of DOI:10.1021/jo00201a016

Syntheses of deoxycorticoids 7b, 8b, and 9b are described.Treatment of 20-oxo steroid 1 with 3 mol equiv of CuBr2 in MeOH in the presence or absence of pyridine gave the 21-bromide 4a or the 17α-methoxide 2 in high yields, respectively.When 6 mol equiv of the brominating reagent was used in the absence of pyridine, the 21-bromo-17α-methoxide 5a was formed. 17α-hydroxy 20-ones 3 could be similarly converted to the 21-bromides 6a and 6b.Oxidation of 4a, 5a, and 6a with CrO3 and subsequent isomerization of a double bond at C-5 with acid gave the corresponding 4-ene-3-ones 7a, 8a, and 9a, of which 7a and 9a were efficiently hydrolized to 7b and 9b under controlled conditions with a K2CO3-H2O-acetone system.On the other hand, 8a was converted to 8b by reaction with NaOCH3 in MeOH.