Mechanism-Guided Scaffold Diversification: Perturbing and Trapping the Intermediates of Maltol-Type Cascade Claisen Rearrangement

A mechanism-guided study to harness different kinds of active species in the cascade Claisen rearrangement for scaffold diversification has been developed. These robust and practical processes furnished a series of architectures with a large chemical space, varying from planar to three-dimensional. In addition, several interesting reactions were observed, such as [3 + 3] dimerization, quinone-based vinylogous Nazarov-type cyclization, and a rare 12e [sigma 2a + pi 2s + pi 2a + pi 2s + (pi 2a + pi 2s)] Mobius aromatic transition state mediated rearrangement.