Aggregative activation in heterocyclic chemistry. Part 6.† A surprising NH3 effect during metallation of 2-methoxypyridine with a multimetal complex base: C-3 versus C-6 metallation

The new bimetallic complex base prepared from Me2N(CH2)2OH (DMAE), NaNH2 and BuLi has been found to exhibit a particular behaviour. Thus, the presence of ammonia in these basic aggregates induces the C-3 metallation of 2-methoxypyridine while the base obtained from DMAE, NaH and BuLi promoted, like BuLi–DMAELi, metallation at the C-6 position. A reaction profile showed that both metallated species can be obtained by removing and adding ammonia respectively.