Preparation of cyclic ketals

A 3-cyclic ketal of an alkyl 3-keto-11-(b )-hydroxy - 4,17(20) - pregnadiene - 21 - oate is obtained by reducing with sodium borohydride a 3-cyclic ketal of an alkyl 3,11-diketo-4,17(20)-pregnadiene-21-oate having the formula <FORM:0771152/IV(b)/1> wherein R is hydrogen or a lower alkyl group...

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Bibliographic Details
Main Authors O¾ PHILIP FRANKLIN BEAL, HOGG JOHN ALEXANDER
Format Patent
LanguageEnglish
Published 27.03.1957
Subjects
CHEMISTRY
METALLURGY
ORGANIC CHEMISTRY
STEROIDS
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Summary:A 3-cyclic ketal of an alkyl 3-keto-11-(b )-hydroxy - 4,17(20) - pregnadiene - 21 - oate is obtained by reducing with sodium borohydride a 3-cyclic ketal of an alkyl 3,11-diketo-4,17(20)-pregnadiene-21-oate having the formula <FORM:0771152/IV(b)/1> wherein R is hydrogen or a lower alkyl group containing 1-8 carbon atoms inclusive, and n is one or two. The reaction may be effected in an aqueous alkali containing lower alkanol as the reaction solvent and at a reaction temperature between 35 DEG to 50 DEG C. Subsequently the 3-cyclic ketal of the alkyl 3-keto-11(b )-hydroxy-4,17(20) - pregnadiene - 21 - oate may be reduced with lithium aluminium hydride to produce the 3-cyclic ketal of 11b ,21-dihydroxy4,17(20) - pregnadiene - 3 - one. An example discloses the production of the 3-ethylene glycol ketal of methyl 3-keto-11(b )-hydroxy4,17(20) - pregnadiene - 21 - oate and of the 3-ethylene glycol ketal of 11b ,21-dihydroxy-4, 17(20) - pregnadiene - 3 - one. Other 3 - ketals are prepared in a similar manner.
Bibliography:Application Number: GB19550016469