Synthesis of Non-Aromatic Pyrroles Based on the Reaction of Carbonyl Derivatives of Acetylene with 3,3-Diaminoacrylonitriles

The reaction of 3,3-diaminoacrylonitriles with DMAD and 1,2-dibenzoylacetylene was studied. It is shown that the direction of the reaction depends on the structure both of acetylene and of diaminoacrylonitrile. In the reaction of DMAD with acrylonitriles bearing a monosubstituted amidine group, 1-substituted 5-amino-2-oxo-pyrrole-3(2H)ylidenes are formed. On the other hand, a similar reaction of acrylonitriles containing the N,N-dialkylamidine group affords 1-NH-5-aminopyrroles. In both cases, pyrroles containing two exocyclic double bonds are formed in high yields. A radically different type of pyrroles containing one exocyclic C=C bond and sp(3) hybrid carbon in the cycle is formed in reactions of 3,3-diaminoacrylonitriles with 1,2-diaroylacetylenes. As in reactions with DMAD, the interaction of 3,3-diaminoacrylonitriles with 1,2-dibenzoylacetylene can lead, depending on the structure of the amidine fragment, both to NH- and 1-substituted pyrroles. The formation of the obtained pyrrole derivatives is explained by the proposed mechanisms of the studied reactions.

Automated summary

The reaction of 3,3-diaminoacrylonitriles with DMAD and 1,2-dibenzoylacetylene was investigated, and the direction of the reaction was found to depend on the structure of both acetylene and diaminoacrylonitrile. Different types of pyrroles were formed depending on the substituents on acrylonitriles and the amidine fragment in the reactions. The proposed mechanisms provide explanations for the formation of the obtained pyrrole derivatives.