A formal [3 + 3] cycloaddition reaction. 5. An enantioselective intramolecular formal aza-[3 + 3] cycloaddition reaction promoted by chiral amine salts.

A detailed account on chiral secondary amine salt promoted enantioselective intramolecular formal aza-[3 + 3] cycloadditions is described here for the first time. The dependence of enantioselectivity on the structural feature of these chiral amines is thoroughly investigated. This study also reveals a very interesting reversal of the stereochemistry in the respective cycloadducts obtained using C(1)- and C(2)-symmetric amine salts. In addition, the influence of solvents, counteranions, and temperatures on the enantioselectivity is described, and a unified mechanistic model based on experimental results as well as semiempirical calculations is proposed.