SU491630A1 - The method of obtaining -carbolin - Google Patents

Description

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This invention relates to an improved process for the preparation of α-carbolines, which can be used as intermediates in the synthesis of pharmaceuticals and dyes.

A known method for producing a-carbolines by reacting a base of 2-amipoindole or a salt of such 2-aminoindole with the addition of an equivalent amount of a strong base, such as triethylamine, with 1,3-diketopes in an organic solvent, followed by isolation of the target product. There is also known a method for the preparation of 9-methyl-a-carbolines by the reaction of L-alkyl-2-aminoindole with malonic dialdehyde in a yield of 8%. But the 2-aminoindoles required in the synthesis are difficult to access and unstable during storage even in the form of salts, and the yield of the target product by the interaction of 2-aminoindole with 1,3-dialdehydes is small.

An improved method for the preparation of α-carbolines is described, in which 1,3 dioxo compounds are reacted with 2-arylsulfamidoindolamn, for example 2-tosylaminoindole, or its substituted at position 1 or in the benzene ring, in a strong, for example sulfuric acid, followed by isolation of the desired product known techniques. The process is best conducted at 80-100 ° C.

Conducting the reaction in a strong acid does not reduce to the formation of the corresponding salt of 2-aminoindole, since when heated 2tosylaminoindole in a strong acid in the absence of 1,3-dioxo compounds, 2-hydroxyindole and l-toluenesulfamide are formed. Apparently, it can be assumed that the rupture of the N-S bond occurs at some intermediate cyclization stage. This is a fundamental difference.

from the known method, where the salt of 2-aminoindole is reacted.

The resulting a-carbolines have a characteristic luminescence in UV light.

The structure of the resulting compounds; proven

by comparison with samples of known structure by IR, UV spectra and melting point.

PRI. M ER 1. Getting 2,4-dimethyl-a-carboline.

A mixture of 1 g of 2-tosylaminoindole, 0.75 g of acetylacetone and 12 ml of 70% H2SO4 is heated at 100 ° C for 1 hour. After cooling, 10 ml of water is added to the reaction mixture, then brought to a mixture with the help of shellox.

alkaline reaction. The resulting precipitate is separated, washed with water and recrystallized from methanol. Obtain 0.57 g (80%) of product with so pl. 222 224C.

Example 2. Getting 6-methoxy-2,4-dimethyl-a-carboline.

Similarly, from 0.2 g of 5-methoxy-2-tosylaminoindole and 0.4 g of acetylacetone, 0.285 g (82%) of the product with m.p. 225-227 ° C.

Example 3. Getting 2,4,9-trimethyl-okarbolin.

Similarly, from 0.1 g of 1-methyl-2-tosylaminoindole and 0.1 g of acetylacetone, 0.046 g (62%) of the product with m.p. PO-11 HS.

PRI me R 4. Getting 2,4-dibenzoyl-a-carboline.

4 ml of concentrated sulfuric acid is added to a mixture of 0.5 g of 2-tosylaminoindole, 0.5 g of dibenzoylmethane, 8 ml of alcohol, and heated at 90 ° C for 4 hours. The results are isolated in a known manner and 0.32 g (58% ) product with m. pl. 222-224 ° C.

Example 5. Obtaining 2-methyl-4-phenyl-acarboline and 2-phenyl-4-methyl-a-carboline.

Similarly, from 0.5 g of 2-tosylaminoindole and 0.42 g of benzoylacetone when heated for 1 hour, 0.272 g (61%) of 2-methyl-4-phenyl-a-carboline with m.p. 230-231 ° C and 0.085 g (18%) of 2-phenyl-4-methyl-a-carboline with so pl. 190-192 ° C.

Example 6. Obtaining 2-methyl-a-carboline and 4-methyl-a-carboline.

Similarly, from 0.5 g of 2-tosylamino and

0.5 g formylacetone natrienol ta receive

0.261 g (80%) of 2-methyl-a-carboline with so pl.

251-253 ° C and 0.26 g (8%) of 4-methyl-.a-carboline

with t. pl. 215-216 ° C.

All the products obtained are identical with samples of known structure by IR, UV spectra and melting point.

Claims (2)

1. A method of producing α-carbolines based on 1,3-dioxo compounds by heating, characterized in that, in order to simplify the process and increase the yield of the target product, the 1,3-dioxo compounds are reacted with 2-aryl sulfono-di-dipole and the process is conducted in a strong acid medium , for example sulfuric acid, with the subsequent isolation of the target product by known techniques. 2. A method according to claim 1, characterized in that the process is carried out at 80-100 ° C.