A Cascade Synthesis of Aminohydantoins Using In Situ‐Generated N ‐Substituted Isocyanates

Nitrogen‐substituted isocyanates are rarely utilized but powerful building blocks for the development of cascade reactions in heterocyclic synthesis. These reactive amphoteric intermediates can be accessed in situ via an equilibrium that allows controlled reactivity in the presence of bifunctional partners such as α‐amino esters. A cascade reaction has been carried out that forms 3‐aminohydantoin derivatives using simple phenoxycarbonyl derivatives of hydrazides and hydrazones as precursors of N ‐substituted‐isocyanates. This method allows rapid assembly of complex aminohydantoin derivatives, including analogues of medicinally‐relevant compounds, using simple reactants.