C-5 FUNCTIONALIZATION OF TRISUBSTITUTED IMIDAZOLES WITH AZODICARBONYLCOMPOUNDS

Certain 1,2,4-trisubstituted imidazoles underwent electrophilic attack of azodicarbonyl compounds on the 5-position to form 5-(1,2-dialkoxyc arbonyl)hydrazino- and -phenyl-3,5-dioxo-1,2,4-triazolidin-1-yl)imidaz ole derivatives in moderate to high yields. The reaction was highly su sceptible to the nature and the substitution pattern of the substituen ts on the imidazole ring. Thus 1,4-di- or 1,2,5-trisubstitued imidazol es, and 2-methylsulfinylimidazoles gave no reaction. Reductive cleavag e of the tetrasubstituted imidazoles with zinc dust-acid gave the 1- o r 1,2-cleaved product depending upon the reaction temperature, but the hydrazino moiety remained intact.