| abstract |
Process for the preparation of pyrrolo- [3,4-c] pyrroles of the formula (1) in which R and R 2 are alkyl or aralkyl groups, isocyclic or heterocyclic aromatic radicals, characterized in that an ester of the formulas (2) or (3) with a nitrile of the formula R 2 CN in the presence of a strong base in an organic solvent, where R and R 'are alkyl or aryl radicals, and R and R 2 have the meaning already given. Compounds of formula (8) wherein R 3 is an alkyl, aralkyl group or an ortho-substituted isocyclic or heterocyclic aromatic radical and R 4 is an alkyl or aralkyl group or an isocyclic or heterocyclic aromatic radical.n n n The pyrrolo-pyrroles obtained are valuable pigments that dye high-molecular compounds such as plastics and paints in yellow to red shades with excellent fastness properties. |