Benz-3-carbolines

Whereas j3-carboline derivatives abound in nature, other carbolines are virtually unknown in living systems. The only exception is a benz-8-carboline derivative, cryptolepine (78). Two alternative biogenetic... 

A S3mthetic approach to the same tetracyclic y-carboline nucleus (235) is the consecutive Fischer indole and Bischler-Napieralski ring closure of o-acetamidoacetophenone methylphenyUiydr one (234). The Bischler-Napieralski reaction has also been used in the synthesis of 3,4-benz-j8-carbolines (236) and 3,4-benz-8-carbolines, e.g. 237... 

The quindoline 224may be prepared by the condensation of indoxyl-2-carboxylic acid with 6-aminopiperonaldehyde in the presence of hydrochloric acid, when decarbo lation and cyclization take place. Nitric acid oxidation of 224 gave an unstable nitrodicarboxylic acid which decarboxylated readily to a nitromonocarboxylic acid formulated as 8-nitro-3-carboline-3-carboxylic acid (225). g. Miscellaneous Methods, A variety of methods lead to benz-carboline derivatives. Only a few of the more unusual ones will be... 

The ultraviolet spectra of a-, V" 8-carboline have been recorded, as well as those of a number of benz-carbolines (2,3-benz-a- 454 2,3-benz-8-, and 3,4-benz-j8-carboline and quaternary benzcarbolinium salts (2,3-benz-y- and l,2-benz-/S-carbolinium Whereas the spectra of a- and j8-carboline are quite similar, both differ substantially firom that of S-carboline. ... 

The extension of the method to the synthesis of y-carboline from 1-y-pyridylbenztriazole (199) and of a 3,4-benz-y-carboline from a l-(4-quinolyl)benztriazole proceeded smoothly. In an alternative approach excellent yields of y-carboline were obtained by heating l-phenylpyrido[3,4-d] -triazole (200) at 320-350°. The synthesis of halogeno-substituted j8- and y-carbolines via the Graebe-Ullmann reaction has been reported. ... 

Dihydro-l-oxo-3,4-benz-j8-carboline (166) reacted with phosphorus oxychloride and one mole of phosphorus pentachloride at 110° to give l-chloro-3,4-benz-j8-carboline (264). When, however, more than one mole of phosphorus pentachloride was used 265 was obtained, presumably by chlorination of 264. This chlorinating action of phosphorus pentachloride is analogous to that observed when an... 

Ultraviolet spectra of a l,2-dihydro-y-carboline derivative and of a number of quaternary l,2-benz-3,4-dihydro-j8-carbolinium derivatives and of the anhydro-bases derived from them have been... 

Whereas j8-carboline derivatives abound in nature, other carbolines are virtually unknown in living systems. The only exception is a benz-S-carboline derivative, cryptolepine (78). Two alternative biogenetic schemes, one based on tryptophan and o-methylaminobenzalde-hyde, the other based on an anthranilic acid-erythrose adduct and a second anthranilic acid unit, have been proposed. The origin of a-carboline, which has been isolated from coal tar oil has not been considered. 

Ultraviolet spectra of a 1,2-dihydro-y-carboline derivative and of a number of quaternary l,2-benz-3,4-dihydro-j8-carbolinium derivatives and of the anhydro-bases derived from them have been recorded. It is noteworthy that introduction of a 6-hydroxyl group does not affect the spectrum of the l,2-benz-3,4-dihydro-j8-carbolinium ion, whereas introduction of a 7-methoxyl group leads to a bathochromic shift of 20... 

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