Synthesis of a tetrabenzyl-substituted 10-membered cyclic diamide

A conformationally constrained 10-membered cyclic diamide was designed and synthesized. Conformational analysis suggested that the 9-membered ring formation was preferred to the direct formation of 10-membered ring. On the basis of the prediction, lactonization of 9-membered lactone, followed by intramolecular ester–amide transformation afforded the desired 10-membered cyclic diamide.