New 17-desoxy corticosteroids and processes for their preparation

摘要

The invention comprises compounds having the general formula: FORM:0970482/C1/1 in which R1 is the oxygen atom of a ketone group or an 11b -hydroxyl group and R2 is hydrogen or an acyl radical derived from an organic acid and which may also contain substituents in the A and B rings, and processes for the preparation thereof by subjecting 3a -hydroxy-16a -methyl-5b -pregnane-11, 20-dione to selective halogenation to yield the corresponding 21-halogeno derivative having the general formula: FORM:0970482/C1/2 wherein X and Y are both iodine atoms or wherein X is a halogen atom and Y is a hydrogen atom, reacting this compound with an acylating agent to yield a 3a -hydroxy-16a -methyl-21-acyloxy-5b -pregnane-11, 20-dione, oxidizing the 3a -hydroxy-16a -methyl-21-acyloxy-5b -pregnane-11, 20-dione to the corresponding 16a -methyl-21-acyloxy-5b -pregnane-3, 11, 20-trione, which is dibrominated to produce the corresponding 2a , 4b -dibromo-16a -methyl-21-acyloxy-5b -pregnane 3, 11, 20-trione and dehydrobrominated so as to introduce thereinto 1- and 4-double bonds yielding the corresponding 16a -methyl-21-acyl-17-desoxyprednisone. Selective halogenation may be effected with bromine in the presence of acetyl chloride or with iodine in the presence of calcium oxide and calcium chloride. Dibromination may be effected with bromine in ethyl acetate and dehydrobromination by a lithium bromide-lithium carbonate couple. Esterification may be effected at 21-position, 16a -methyl-17-desoxyprednisone or a 21-ester thereof may be reduced e.g. with potassium borohydride to the corresponding prednisolones after protecting the ketone groups at 3 and 20-positions with semi-carbazone. Specifications 970,481 and 970,487 are referred to.