Process of preparation of beta-methasone

Claim 1

A PROCESS FOR THE PREPARATION OF 21-ACETOXY-16BMETHYL - $1,4,9(11)-PREGNATRIENE - 17A-OL-3,20 - DIONE WHICH COMPRISES THE STEPS OF (A) REACTING 3A-ACYLOXY-16A,17AOXIDE-5B-PREGNANE-11,20-DIONE WHEREIN ACYL REPRESENTS THE ACYL RADICAL OF AN ORGANIC CARBOXYLIC ACID HAVING FROM ONE TO EIGHTEEN CARBON ATOMS WITH AN ETHYLENE KETAL-PRODUCING COMPOUND UNDER EKTALIZING CONDITIONS, (B) REACTING THE 3A-ACYLOXY:16A-17A-OXIDO-20,20-ETHYLENEDIOXY-5B-PREGNANE-11-ONE WITH AN ALKALI METAL BOROHYDRIDE IN AN INERT AQUEOUS ORGANIC SOLVENT, (C) ESTERIFYING THE ALOCHOL IN THE 3-POSITION OF 16A,17A-OXIDO-20,20ETHYLENEDIOXY-5B-PREGNANE-3A,11B-DIOL BY THE ACTION OF A FUNCTIONAL DERIVATIVE OF AN ORGANIC CARBOXYLIC ACID HAVING FROM ONE TO EIGHTEEN CARBON ATOMS, (D) SUBJECTING THE 3A,ACYLOXY - 16A,17A - OXIDO - 20,20 - ETHYLENEDIOXY5B-PREGNANE-11B-OL WHEREIN ACYL HAS THE ABOVE-ASSIGNED MEANING TO THE ACTION OF A HYDROCARBON SULFONYL CHLORIDE, (E) REACTING THE 3A-ACYLOX-16A,17A-OXIDO-20,20ETHYLENEIDIOXY - $9(11) - 5B - PREGNENE WHERE ACYL HAS THE ABOVE-ASSIGNED MEANING WITH A METHYL MAGNESIUM HALIDE IN THE PRESENCE OF AN INERT ORGANIC SOLVENT, (F) OXIDIZING THE ALCOHOL IN THE 3 POSTION OF 16B-METHYL-$9(11)5B-PREGNENE-3A,17A-DIOL-20-ONE BY THE ACTION OF AN ACIIDIC OXIDIZING AGENT, (G) SUBJECTING THE 16B-METHYL-$9(11)5B-PREGNENE-17A-OL-3,20-DIONE TO THE ACTION OF BROMINE UNDER BROMINATING CONDITIONS, (H) DEHYDROBROMINATING THE 2B,4B - DIBROMO - 16B - METHYL-$9(11)-5B-PREGNENE17A-OL-3,20-DIONE BY THE ACTION OF AN ALKALINE AGENT AT ELEVATED TEMPERATURES, (I) SUBJECTING THE 16B-METHYL$1,4,9(11)-PREGNATRIENE-17A-OL-3,20-DIONE TO THE ACTION OF IODINE IN THE PRESENCE OF CALCIUM HYDROXIDE AND ALCIUM CHLORIDE, (J) REACTING THE 21-DIIODO-16B-METHYL-$1,4,9(11)PREGNATRIENE-17A-OL-3,20-DIONE WTH AN AKALI METAL ACETATE IN AN INERT ORGANIC SOLVENT, AND (K) RECOVERING, SAID 21 - ACETOXY- 16B - METHYL - $1,4,9(11)-PREGNATRIENE - 17A-OL3,20-DIONE.