Methoxycarbonylphenyl pyrrole

Methyl anthranilate from Eastman Kodak Company was used without further purification. 

5-Dimethoxytetrahydrofuran from Eastman Kodak Company was used without further purification. This material also can be prepared by catalytic hydrogenation2 of 2,5-dimethoxy-2,5 -dihy drof uran. 3 

The submitter reports that much heat is liberated during the addition the checkers did not find the reaction to be markedly exothermic. 

The condensation of primary amines with 2,5-dialkoxytetra-hydrofurans to give in one step N-substituted pyrroles is applicable to a variety of substituted aliphatic and aromatic amines.6 The method, largely developed by Clauson-Kaas and associates, has the advantages of simplicity, mild conditions, and generally excellent yields from readily available starting materials. 

The submitter has used the method to prepare the corresponding 1-pyrrolyl derivatives6 from the following amines in the indicated yields ethyl /3-aminobutyrate 88%, methyl -amino-glutarate 87%, /3-aminopropionitrile 58%, and 2,5-diamino-3,4-dicyanothiophene 22%. 

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On saponification l-(2-methoxycarbonylphenyl)pyrrole yields l-(2-carboxyphenyl)pyrrole, m.p. 106-107°, which on reaction with polyphosphoric acid at 70° is cyclized to 9-keto-9H-pyrrolo-(l,2-a)indole in 28-32% yield. Through the choice of the appropriate amine and acetal components, the substituted l-(2-meth-oxycarbonylphenyl)pyrroles become readily available intermediates in the preparation of a variety of derivatives of the pyrrolo( 1,2-a) indole ring system. 

FVP of l-(2-methoxycarbonylphenyl)pyrrole 19 at925°C (0.001 Torr) gives the unusual 5//-pyrrolo[2,l- 7]isoindol-5-one system 21 (79%) by a novel three-step cascade process involving rate-determining [l,5]-aryl migration. 

Josey, A. D. 1973. l-(2-Methoxycarbonylphenyl)pyrrole. In Organic syntheses, Collective volume 5, ed. H. E. Baumgarten, 716-717. New York John Wiley Sons. 

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