M.M. Efremova, R.R. Kostikov, A.V. Stepakov, T.L. Panikorovsky, V.S. Shcherbakova, A.V. Ivanov, A.P. Molchanov
“Unusual Lewis-acid catalyzed formal (3+3)-cycloaddition of azomethine imines and nitrones to N-vinylpyrroles”
Tetrahedron, 2017, 73, 671-680
DOI: 10.1016/j.tet.2016.12.034
The addition of Lewis acids change the reaction mechanism of the cycloaddition of N-vinylpyrroles with azomethine imine and C,N-diarylnitrones. The formal (3+3)-cycloaddition is observed instead of (3+2)-dipolar cycloaddition, which take place in the absence of catalysts. This unusual (3+3)-cycloaddition leads to heterocyclic compounds with pyrazolo[1,2-a]pyrrolo[1,2-d][1,2,4]triazine- and pyrrolo[2,1-d][1,2,5]oxadiazine cores, which are difficultly achievable by other methods.