α-(Dialkylamino)-α-pyrrolylacetonitriles. A potpourri of useful synthetic transformations

α-(Dialkylamino)-α-(pyrrol-2-yl)acetonitriles (3) are versatile intermediates that are readily converted into regiochemically pure 2-bromo-6-dialkylamino-1-azafulvenes and 5-bromo-2-acylpyrroles (acyl = CHO, COR). In addition, 3 (R 1 = H), 4 (R 1 = H), and the β-substituted compound 9 are transformed easily and under mild conditions, via the corresponding α-methylthio compounds (e.g., 7a), into the methyl pyrrole carboxylates 8a, 8b, and 10, respectively.