Synthesis of 3-oxo-1,4-diazepine-5-carboxamides and 6-(4-oxo-chromen-3-yl)-pyrazinones via sequential Ugi 4CC/Staudinger/intramolecular nucleophilic cyclization and Ugi 4CC/Staudinger/aza-Wittig reactions

An efficient approach for the assembly of 1,4-diazepine-based and 6-(4-oxo-chromen-3-yl)-pyrazinonebased frameworks has been developed that involves the Ugi four-component reaction (U-4CR) followed by Staudinger/nucleophilic cyclization and Staudinger/Aza-Wittig reactions, respectively. This convergent approach exhibits a high bond-forming efficiency, involving the use of readily available commercial reagents and is an example of the reconciliation of structural complexity with operational simplicity in a time- and cost-effective manner. (C) 2014 Elsevier Ltd. All rights reserved.