Diastereodivergent synthesis of chromeno[2,3-b]chromenes by tuning all of the reactivity centers of isocyanoacetate

A novel diastereodivergent tricyclization of isocyanoacetates with o-quinone methides was accomplished for the efficient synthesis of chromeno[2,3-b]chromene derivatives. All three reactive centers of isocyanoacetate reacted sequentially with two o-QMs, affording the products with four adjacent stereocenters in a diastereoselective manner. The asymmetric version was preliminarily investigated.