Reactivity of 1,3-Diimines. Reaction with Heterocumulenes

Article abstract of DOI:10.1021/jo01301a010

1,3-Diimines 1 react with isocyanates and isothiocyanates 2 to give, as the major products, different 2-oxo- and 2-thiopyrimidines 9 and 10.The formation of these products can be explained by two different reaction paths that involve an addition reaction followed by an electrocyclic ring closure.The nature of the group R1 in 1 plays a basic role in the result of the process.Open-chain intermediate products 3 have been isolated and characterized for the first time in a cyclization reaction with diimines 1.