Cyclizative Dearomative Rearrangement of Pyridines with Isocyanates

Dearomatizationof pyridines is a robust synthetic method to access aza-heterocycles. Simultaneously, intermolecular cyclizative rearrangement is a recently developed new strategy toward efficiently constructing tetrasubstituted carbons. Here, we show that an effective integration of dearomatization approach with strategic cyclizative rearrangement render 2-acyl-substituted pyridines and their analogues with common isocyanates to undergo a tandem [3+2] heteroannulation followed by an extensive 1,2-carbon shift, thus providing a straightforward access to readily functionalized bicyclohydantoins. Based on the promotion of organophosphorus, different types of migrating groups, such as ester, amide, aryl and trifluoromethyl groups, are all well-tolerated in the same reaction for the first time.