Patent GB-971183-A (GB)
Title: Process for the manufacture of steroids having an 11ª‰:18-oxygen bridge
IPC: C07J75/00
Filed: 1961-02-20
Abstract: The invention comprises (1) a process for the preparation of steroids containing an 11b ,18-oxygen bridge wherein an 18-oxygenated 11a -sulphonyloxy-steroid is treated with a basic agent capable of forming an oxygen anion in position-18; and (2) as a new class of steroids, 18-alkoxy-11b ,18; 18,20-bis-oxido-steroids.  From an 18-hydroxy or acyloxy-steroid an 11b ,18-oxido-steroid is formed, while an 18-oxo-steroid gives an 11,18-semi-acetal of an 11b -hydroxy-18-ol and an 18-carboxy-steroid or an ester or lactone thereof gives an 18,11-lactone of an 11b -hydroxy-18-acid or-ortho-acid.  The 18-alkoxy-11b ,18; 18,20-bis-oxido-steroids are formed from 18,20-lactones of 20-hydroxy-steroid 18-acids and alkoxides of alkali metals under substantially anhydrous conditions, and on heating with aqueous acid they yield 11b ,18-lactones of 20-hydroxy-steroid 18-acids.  Suitable basic agents are hydroxides and alkoxides of alkali or alkaline earth metals, alkali metal carbonates and amines and cyclic amines, or even, for use with 18-aldehydes, salts of strong bases with weak acids, such as alkali metal salts of carboxylic acids.  In examples (1) the 18,20-lactone of D 4-3- oxo - 11a ,20b -dihydroxy-pregnene-18-acid (prepared by hydrolysis of the 11-acetate) is converted to the 11-tosylate, and this on heating with potassium carbonate in aqueous alcohol gives the 18,11-lactone of D 4-3-oxo-11b ,20b -dihydroxy-pregnene-18-acid, which on oxidation gives the corresponding 20-one and a little of the 18,20-lactone of D 4-3,11-dioxo-20b -hydroxy-pregnene-18-acid; (2) the 18,20-lactone of D 5-3-ethylenedioxy-11a -tosyloxy-20b -hydroxy-pregnene -18-acid (prepared by hydrolysing the 18,20-lactone of D 5-3-ethylenedioxy-11a -acetoxy-20b -hydroxy-pregnene -18-acid, itself prepared by ketalization of the D 4-3-one, to the 11a -ol and tosylating this) by the process of (1) gives the 18,11-lactone of D 5-3-ethylenedioxy-11b ,20b -dihydroxy-pregnene-18-acid which on oxidation gives the 20-one; (3) D 4-3-oxo-11a -tosyloxy-18-hydroxy-18,20b -oxido-pregnen (prepared by tosylation of D 4-3-oxo-11a -hydroxy-18-methoxy-18,20-oxido-pregnene, itself prepared by methylation of the 18-ol) is heated with potassium acetate in dimethylformamide to give D 4-3-oxo-11b ,18: 18,20b -bis-oxido-pregnene; (4) D 5-3-ethylenedioxy-11a -tosyloxy-18,20b -diacetoxy -pregnene (prepared by reducing the 18,20-lactone of D 5-3-ethylenedioxy-11a -acetoxy-20b -hydroxy-pregnene-18 -acid to D 5-3-ethylenedioxy-11a , 18, 20b -trihydroxy-pregnene, converting this to the 18,20-diacetate, and tosylating this) by the method of (1) gives D 5-3-ethylenedioxy-11b ,18-oxido-20b -hydroxy-pregnene, which on oxidation gives the 20-one; (5) the starting material of (2) is heated with triethylamine in aqueous dioxan to give the product of (2) and the 18,20-lactone of D 5,9(11)-3-ethylenedioxy-20b -hydroxy -pregnadiene-18-acid, and, similarly, the 18,20-lactone of D 5-3-ethylenedioxy-11a -tosyloxy-20a -hydroxy-pregnene -18-acid (prepared from the 11a -acetoxy compound by the method of (2)) gives the corresponding 20a -compounds; (6) the starting material of (2) is heated with methanolic KOH to give D 5-3-ethylenedioxy-11b ,18: 18,20-bis-oxido-18-methoxy-pregnene, and the corresponding D 4-3-one is prepared similarly; (7) D 4-3,18,20-trioxo-11a -tosyloxy-21-acetoxy-pregnene (prepared by reducing D 4-3,20-dioxo-11a -tosyloxy-21-acetoxy-pregnene, itself prepared by tosylation, to give D 4-3,20-dihydroxy-11a -tosyloxy-21-acetoxy-pregnene, oxidizing this to the corresponding 3-one, reacting this with nitrosyl chloride to give the 20-nitrite, irradiating this in toluene with a high pressure mercury lamp to give the 18-oxime of D 4-3, 18 - dioxo - 11a  - tosyloxy-20-hydroxy-21-acetoxy -pregnene, oxidizing this to the corresponding 20-one, and hydrolysing this under acid conditions) is heated with sodium acetate in acetic acid to give aldosterone-21-acetate; and (8) the 18,20-lactone of 3a -acetoxy-11a -tosyloxy-20b -hydroxy-pregnane-18-acid (prepared by tosylation of the 11-ol) by the method of (5) gives the 18, 11-lactone of 3a -acetoxy-11b , 20b -dihydroxy-pregnane-18-acid and the 18,20-lactone of D 9(11)-3a -acetoxy-20b -hydroxy-pregnene-18-acid. Some of these processes are also referred to in more general terms, and reference is also made to the preparation of 18,20-lactones of 20-hydroxy-pregnane-18-acids by acylating 18,20-oxido-pregnane to give 18,20-diacyloxy-pregnanes, hydrolysing these to 18,20-dihydroxy-pregnanes and oxidizing these; and to the preparation of 18-oxo-pregnanes by oxidizing 18-unsubstituted 20-hydroxy-pregnanes with lead acetate and iodine in cyclohexane, treating with potassium acetate and hydrolysing, which semi acetals may, if desired, be oxidized to 18,20-lactones.