Structure‐Directed Synthesis under Thermodynamic Control: Macrocyclic Trimers from Cinchona Alkaloids

A remarkably narrow product distribution is observed in the thermodynamic cyclization of modified Cinchona alkaloids to yield predominantly the trimer 1 (X = H, OMe); this is a representative of a new class of macrocycle. The reaction was proved to be reversible by resubmitting the cinchonidine (X = H) and quinine (X = OMe) to the reaction conditions: a statistical mixture of all four possible trimers was obtained.