Modular Maleimide Synthesis from Ynamides

generated lithiated ketenimines, engaging in a cascade sequence involving formal anionic (2 + 2) cycloaddition, cycloreversion, and cyclocondensation, is reported. This method enables rapid access to a wide range of densely functionalized maleimides with excellent functional group tolerance, under conditions allowing either retention or removal of the N-protecting group. The resulting scaffolds can be readily diversified, notably through a "nitrogen switch" strategy, to access distinct heterocycles. The power of this approach is demonstrated in the concise syntheses of denigrin A and aqabamycin A, as well as the first unified and divergent synthesis of antrodins A-C, highlighting its potential as a versatile platform for the rapid construction of functional maleimide architectures.