Process for producing an estrone acetal

Details Process for producing an estrone acetal Process for producing an estrone acetal

1984-09-21

1986-11-11

Roberts, Elbert L.

Chemistry of carbon compounds

Miscellaneous organic carbon compounds

C-metal

540 31, C07J 100

Patent

active

046221816

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

This invention concerns a process for producing an estrone acetal. More particularly, it relates to a process for producing an estrone acetal at a high yield and with economic advantages upon practicing in the industrial scale.
2. Background Art
Estrone acetal is one of important female hormones and is useful as a precursor of estrone as an intermediate to medicines for the therapy of prostatic hypertrophy and other steroid type medicines.
Heretofore, as a method of producing an estrone acetal from androstane-1,4-diene-3,17-dione-17-acetal (hereinafter abbreviated as "ADDK"), there is, for instance, a method as described in Japanese Patent Application Laid-Open No. 51099/1980 proposed by one of the present inventors.
The above-mentioned method concerns a process for producing estrone comprising preparing radical anions from sodium and a polycyclic aromatic compound in a mixed solvent of tetrahydrofuran and a small amount of polyether, then supplying a tetrahydrofuran solution of ADDK into the reaction mixture obtained to reduce ADDK into an estrone acetal and then deacetalizing the same.
However, this method should be regarded as an invention still at a fundamental stage, which can not attain a sufficient yield upon practicing in the industrial scale and which needs further investigation.
That is, according to the examples of this Laying-Open patent, 80-86% yield has been attained for estrone each by the case of the laboratory scale at gram order. However, when the method is practiced in the industrial scale, only about 40% yield can be attained even in the scale of about 25 liter, for example, as shown in Comparative Example 6 described hereinafter even under the conditions of Example 9 which attained the highest yield.
This invention improves the invention in the above-mentioned Laid-Open patent in view of the above and the object thereof is to provide a process for producing an estrone acetal at a high yield and with economical advantages upon practicing in the industrial scale.


DISCLOSURE OF INVENTION

The gist of this invention resides in a process for producing an estrone acetal which comprises preparing radical anions by reacting sodium and a polycyclic aromatic compound in a reaction solvent, and supplying a solution or slurry of androstane-1,4-diene-3,17-dione-17-acetal (hereinafter abbrevaited as "ADDK") prepared in a low boiling supplying solvent into the resultant reaction mixture and reducing the same into an estrone acetal, characterized in that
(a) a solvent satisfying the conditions that: of the total ADDK to be supplied, the total ADDK to be supplied, and times of the total ADDK, is used as the reaction solvent,
(b) the temperatures for the preparing reaction of the radical anions and the reducing reaction of ADDK are from the melting point of sodium to 105.degree. C., and
(c) the ADDK supplying solvent is distilled out of the reaction system as required so that the reaction solvent can always maintain the above-mentioned conditions (ii)-(iv).
This invention is to be described specifically.
As the starting material, that is, ADDK for use in this invention there are mentioned, for example, an androstane-1,4-diene-3,17-dione-17,17-dialkylacetal represented by the general formula (I) and androstane-1,4-diene-3,17-dione-17-alkylene acetal represented by the general formula (II): ##STR1## (wherein R represents a lower alkyl group with 1-6 carbon atom number), ##STR2## (wherein R.sup.1 represents a lower alkylene group with 2-6 carbon atom number).
As specific examples of these ADDKs, there are mentioned, for instance, the following compounds: androstane-1,4-diene-3,17-dione-17,17-dimethylacetal, androstane-1,4-diene-3,17-dione-17,17-diethylacetal, androstane-1,4-diene-3,17-dione-17,17-dipropylacetal, androstane-1,4-diene-3,17-dione-17-ethyleneacetal, androstane-1,4-diene-3,17-dione-17-propyleneacetal.
While metallic sodium is usually employed as sodium, sodium alloys containing a small amount of other alkali metals or alkaline earth metals may be used so long as their melting poi

REFERENCES:
patent: 2356154 (1944-08-01), Fernholz
Chem. Abstracts vol. 93 (1980) Par. 132,688k.
Chem. Abstracts vol. 95 (1981) Par. 133,249w.

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