Preparation of Some Pyrrole-3,4-dicarboxylic Acid Derivatives and the Crystal Structure of 2-Methylpyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione

Abstract

A series of pyrrole-3,4-dicarboxylic acid derivatives has been prepared, and the crystal structure of one, 2-methylpyrrolo[3,4-c]pyrrole-1,3(2H,5H)- dione, has been determined by X-ray diffraction and refined to a residual R 0.049 for 1415 observed reflections. Crystals are monoclinic, space group P2₁/c, with Z= 8 in a cell of dimensions a 14.775(3), b 7.0692(5), c 15.151(3)Ǻ, β 118.82(8)°. Strain in the planar fused ring system is evident from the widening of the external interring angles to 143°, and from the unusual substituent effects in the ¹³C n.m.r. spectra.