Scheme 6.

Reaction between 1 c and 10 a displaying regioselective C(2)−Br exchange facilitated by the Li−N interaction to give contacted ion pair lithium magnesiate 12 a.

Reaction between 1 c and 10 a displaying regioselective C(2)−Br exchange facilitated by the Li−N interaction to give contacted ion pair lithium magnesiate 12 a.