S(RN)1 reactions can be performed with nitrogen carbanions as nucleoph
iles, and generally the reaction leads to a mixture of isomers. In the
case of the pyrrolyl anion, position 2 is about four times more react
ive than position 3. When the ortho positions of pyrrole are substitut
ed by alkyl groups, the reactivity of position 2 increases while that
of position 3 decreases. With tert-butyl groups as the substituents, n
o reaction at position 2 is observed. With the indolyl anion as the nu
cleophiIe, no substitution at position 2 or at the phenyl ring is obse
rved, and only one product corresponding to monosubstitution at positi
on 3 is obtained. Imidazolyl anions react preferentially at position 4
(5), and substitution of position 2 by a methyl group makes the coupl
ing regioselective.