Reactions of N-unsubstituted 4-amino-1-azadienes towards electrophiles

Article abstract of DOI:10.1055/s-1996-4160

Several reactions releated to the ambident nucleophilicity of N-unsubstituted azadienes 1 are described. Thus, reaction of 1 with alkylating agents and iodobispyridinium tetrafluoroborate (IPy₂BF₄) leads to the C-substituted azadienes 3 and 5 respectively. Azadienes 1 and 3 are converted to the carbonyl derivatives 2 and 4 by mild hydrolysis. On the other hand, azadienes 1, 3 and 5 react through the nitrogen atoms with several carbonyl centered electrophiles to give nitrogen heterocycles such as pyrimidines 6 and 9 and dihydropyrimidines 11. All those processes are totally regioselective, azadienes 1 and 3 showing a lower nucleophilicity at nitrogen than N-substituted azadienes.