Process for the preparation of pyrrolo 3,4-c!pyrroles, and novel pyrrolo 3,4-c!pyrroles

摘要

The invention relates to a process for the preparation of pyrrolo 3,4- c!pyrroles of formula (1) ##STR1## wherein each of R.sub.1 and R.sub.2 independently of the other is an alkyl or aralkyl group or an isocyclic or heterocyclic aromatic radical, which process comprises reacting an ester of formula (2) or (3) ##STR2## with a nitrile of the formula R.sub. 2 CN, in which formulae each of R and R' independently of the other is an alkyl or aryl group, and R.sub.1 and R.sub.2 are as defined above, in the presence of a strong base in an organic solvent. PPThe invention also relates to compounds of formula (8) ##STR3## wherein R.sub. 3 in an alkyl or aralkyl group or an ortho- substituted isocyclic or heterocyclic aromatic radical and R.sub.4 is an alkyl or aralkyl group or an isocyclic or heterocyclic aromatic radical. PPThe pyrrolopyrroles obtained are valuable pigments for coloring compounds of high molecular weight such as plastics and lacquers in yellow to red shades of excellent fastness properties.