DE2114356C3 - Process for the preparation of 2,3-dihydrofluoranthene from 1,23,10b-tetrahydrofluoranthene - Google Patents

Description

The invention relates to a process for the preparation of 2,3-dihydrofluoranthene (III) according to the above Claim. In this process, base-catalyzed air oxidation of 1,2,3,1 ob-tetrahydrofluoranthene is effected (I) in solution and subsequent acidification of the reaction solution directly the dehydration of the lOb-hydroxy-l ^ .lOb-tetrahydrofluoranthene formed (11) in the reaction mixture.

(II)

(Ml)

Both compounds, both the alcohol II and the unsaturated hydrocarbon III, are in the Literature described (A. Slreitwieser and S. Suzuki, Tetrahedron, 1961, Vol. 16, pages 153 to 168 and Crombie, Dean and Shaw, Chemistry and Industry 1970, p. 1469).

According to Streitwieser and Suzuki - after metalation of tetrahydrofluoranthene with butyllithium in heptane under nitrogen - the reaction solution is gassed with oxygen for one hour and then vigorously stirred with saturated aqueous sodium sulfite solution. After peeling off the organic Phase this is chromatographed (aluminum oxide), whereby an eluate is first obtained according to UV spectrography of a mixture of 2,3-dihydrofluoranthene and lOb-hydroxy-tetrahydrofluoranthene represents. Then further impure 1 Ob-Hydroxyd is eluted, which in boiling glacial acetic acid with Hydrogen chloride is dehydrated. Crude 2,3-dihydrofluoranthene is obtained which is obtained by column chromatography is purified in addition to the following recrystallization from ethanol. Compound III is associated with a Melting point of 63-65 ° C obtained in 30% yield. According to Crombie et al. becomes in one something

ίο modified procedure the lOb-Hydroxyd and Compound III obtained therefrom by gasifying tetrahydrofluoranthene-lithium with oxygen and the reaction mixture is acidified. The resulting crude alcohol (compound II) is isolated and evidently dehydrated and purified by the method of Streitwieser and Suzuki to give compound III. An allegedly improved method for obtaining the alcohol II is said to be that a solution of Tetrahydrofluoranthene in a 35% solution of benzyltrimethylammonium hydroxide in methanol with Treated oxygen in anhydrous pyridine and. the 1 Ob hydroxide (II) from this reaction mixture Stirring with sodium bisulfite solution is precipitated.

A nitro derivative of 2,3-dihydrofluoranthene (III)

.'-. obtained N. Campbell and J. F. K. Wilshire (J. Chem. Soc. [London] 1954, 867) on the action of nitric acid on tetrahydrofluoranthene (I). This forms initially a nitro derivative of alcohol II, which passes into the end product by splitting off water

so the oxidation of I to alcohol II in this one If the introduction of a NO2 group is necessary, this is a very special one Method with which the unsubstituted alcohol II and the unsubstituted 2,3-DihydroflijOranthene III do not

r. are accessible.

The object of the present invention was accordingly to find a simpler, more economical production process for 2,3-dihydrofluoranthene, as well provides high yields and the use of

ίο makes sodium bisulfite unnecessary.

This object was achieved by the process according to the invention for the preparation of 2,3-dihydrofluoranthene.
As a solvent for tetrahydrofluoranthene in the

• i '· Oxidation stage comes in particular dimethyl sulfoxide. Dimethylformamide, pyridine, quinoline, hexamethylphosphoric acid triamide. Decalin, N-methyl-pyrrolidone and tetrahydrofuran are possible.

Strong bases that catalyze the oxidation are

> <> Sodium ethylate, potassium tert-butylate or a 35% Solution of benzyltrimethylammonium hydroxide in methanol, which is under the protected name "Triton B" is known. The treatment with atmospheric oxygen takes place at temperatures between 10 and 60 ° C.

■> '> The crystalline separation of the end product takes place takes place within 2 to 24 hours depending on the cooling.

2,3-Dihydrofluoranlhen is due to both its

fulvenoid double bond as well as a valuable intermediate product due to its C-H acidity. Mentioned

μ ι are polar additions of secondary amines Formation of new compounds of the pharmacologically active / I-phenylethylamine type and Condensations with aldehydes or ketones, which result in the formation of isomers, substituted in the 2-position, in the

^h > allow the pharmaceutical industry to use fluoranthene.

The following example explains the process according to the invention.

3 4

and conducts oxygen through the solution with stirring.

Example As soon as, after adding the »Triton B« again, none

Red color occurs more, is made with sulfuric acid

10 parts Tetrahydrofluoranthen be acidified at room is 24 hours later in water poured temperature with 15 parts of dimethyl sulfoxide are added 5 and suction filtered and dried in vacuo at 50 ⁰ C. This gives 0.1 parts of the above 35% solution of obtained 10,3Teile (95 ° / o) 2,3-Dihydrofluoranthene (III) Benzyltrimethylammonium hydroxide in methanol added from the melting point 67 to 68.5 ° C.

Claims (1)

Claim: Process for the production of 2,3-dihydrofluoranthene by oxidation of a solution of 1,2,3,10b-tetrahydrofluoranthene and a catalyst with oxygen and dehydration of the 1 Ob-hydroxy-1,2,3,1 Ob-tetrahydrofluoranthene produced thereby characterized in that atmospheric oxygen is added to the solution of l, 2,3 _; 10b-Tetrahydrofluoranthene and catalytic amounts of a strong base at 10 to 60 ° C until complete conversion to lOb-hydroxy-l ^ .lOb-tetrahydrofluoranthene and then without adding hydrogen sulfites and without separating the 10b-hydroxy compound formed, the reaction solution acidified with a strong acid and, after 2 to 24 hours, the 2,3-dihydrofluoranthene formed is separated off in crystallized form after dilution with water.