T. Kazembe, D. Taylor
1980
Citations
0
Influential Citations
18
Citations
Journal
Tetrahedron
Abstract
Abstract 3-Methylindol-2-yl methyl ketone reacted with phosphoryl chloride in dimethylformamide to give 3-chloro-3(3-methylindol-2-yl), propenal ( 4 ). 2-Carbomethoxy- and 2-carbethoxy-1-chloro- 9H-pyrrolo[1,2-a]indol-9-ylidene acetaldehyde ( 10a and b ) were formed by reaction with the same reagent of 3(3-methylindol-2-yl) propenoate ( 7 ) and 3(3-methylindol-2-yl)-3-oxopropanoate ( 2 ) respectively. In the latter case, 2-carbethoxy-1-chloro-3-dimethylamino-9-methyl-3H-pyrrolo[1,2-a]indole ( 9b ) was isolated as an intermediate. The structure of the pyrroloindolylidene acetaldehydes was proved by synthesis of the chromophore from 4-acetyl-3-methyl-1-phenyl-pyrrole-2-carboxylate ( 26 ). The preparation and behaviour of 1-phenylpyrrole-2,4- and 3,4-dicarboxylates, monomethylated in the pyrrole ring, is described. These compounds were prepared during a search for a satisfactory route to a starting material for the synthesis of compounds related to 10a and b . The saponification of such diesters is remarkably selective, and in the case of the 2,4-dicarboxylates, contradicts accepted generalisations concerning the lability of pyrrole α,β-diesters to selective hydrolysis.