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Eine ergiebige Herstellung von 1α,3β‐Dihydroxy‐Δ 5 ‐steroiden durch Reduktion von 1α,2α‐Epoxy‐4,6‐dien‐3‐onen mit Lithium in Ammoniak
Author(s) -
Fürst Andor,
Labler Ludvik,
Meier Werner
Publication year - 1981
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19810640621
Subject(s) - chemistry , lithium (medication) , ammonia , medicinal chemistry , yield (engineering) , ammonium , epoxy , ammonium chloride , stoichiometry , nuclear chemistry , organic chemistry , medicine , materials science , metallurgy , endocrinology
An Efficient Procedure for Preparing 1α,3β‐Dihydroxy‐Δ 5 ‐steroids by Reduction of 1α,2α‐Epoxy‐4,6‐dien‐3‐ones with Lithium in Ammonia A number of 1α,3β‐dihydroxy‐Δ 5 ‐steroids of the cholestane, (20 S )‐20‐methyl‐pregnane (23,24‐dinorcholane), pregnane and androstane series were synthesized from common steroidal precursors. A process originally reported by Barton et al. , based on 1,4,6‐trien‐3‐ones as intermediates, was used for the introduction of the 1α‐hydroxyl function. The last step of this process, consisting of lithium/ammonia reduction of 1α,2α‐epoxy‐4,6‐dien‐3‐ones, was found to be crucial and therefore subjected to particular study. A reproducible procedure permitting high‐yield conversion was developed. It consists of first reducing the epoxydienone with an approximately stoichiometric amount of lithium in ammonia to give, after protonation with ammonium chloride, a 1α‐hydroxy‐5‐en‐3‐one. This intermediate is then further reduced by repeated alternating treatment with ammonium chloride and an equivalent amount of lithium.