The crystal structure of N3,N4-dimethylpyrrole-3,4-dicarboxamide monohydrate has been determined and refined to a residual of 0.034 for 1015 observed reflections. Crystals are monoclinic, space group P21/n with Z 4 in a cell of dimensions a 7.367(2), b 19.984(4), c 7.621(2) �, β 117.84(1)�. The pyrrole ring and the substituent amide side chains are essentially coplanar. The side chains are syn-syn related with an intramolecular hydrogen bond between a carbonyl oxygen of one group and the amide hydrogen of the other [O…N, 2.718(2) � ]. Intermolecular hydrogen bonding is also found between the pyrrole NH group and a carbonyl oxygen [N…O, 2.770(2) � ] and between the lattice water and three separate amide residues [N…O, 2.878(2); OH…O, 2.747, 2.865(2) � ].

The crystal structure of a dimer of 2,3,7,8,12,13,17,18-octaethylporphyrin, joined at the meso-positions through a 2,5-disubstituted furan, shows the furan ring to be almost orthogonal to the porphyrin mean planes. Bond angles and distances in the furan ring and adjacent parts of the porphyrin rings are distorted due to steric congestion involving the ethyl substituents. The dizinc complex of this bis( porphyrinyl )furan exhibits a split Soret band in its electronic spectrum; this indicates strong excitonic coupling between the porphyrin chromophores.

Methyl and ethyl esters of 4-( aminomethyl )pyrrole-3-carboxylic acid were made through pyrrole synthesis with tosylmethyl isocyanide , but cyclization to a bicyclic lactam (1) was not achieved.

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.

The reaction of the anion of ethyl isocyanoacetate with suitably substituted vinyl p- tolyl sulfones gives fair to good yields of pyrrole-2-carboxylates substituted in the 3-, 4- or 3- and 4-positions. From the reaction of 1-phenyl-1-tolylsulfonylethene with ethyl isocyanoacetate , two diastereoisomers of ethyl 4,6-diphenyl-4,6-bis(p- tolylsulfonyl )-3,4,5,6-tetrahydro-2H-azepine-2-carboxylate (4) were also isolated.