An Aldehyde-Driven, Fe(0)-Mediated, One-Pot Reductive Cyclization: Direct Access to 5,6-Dihydro-quinazolino[4,3-b]quinazolin-8-ones and Photophysical Study

A short, proficient, and regioselective synthesis ofbiheterocyclic5,6-dihydro-quinazolino[4,3-b]quinazolin-8-ones hasbeen revealed via an Fe(0)-powder-mediated, one-pot reductive cyclizationprotocol. Mechanistic investigation proved that water acts as a sourceof hydrogen for the reduction of the nitro group and the reactionrate was accelerated by an aldehyde. The designed transformation worksunder aerobic conditions, providing a series of bio-inspired molecularscaffolds. In addition, the photophysical study showed blue fluorescenceemission with a good fluorescence quantum yield.

Automated summary

A short, efficient, and region-selective synthesis of biheterocyclic 5,6-dihydro-quinazolino[4,3-b]quinazolin-8-ones has been achieved via an Fe(0)-powder-mediated, one-pot reductive cyclization protocol. Mechanistic investigation revealed that water serves as a hydrogen source for nitro group reduction and the reaction rate is enhanced by an aldehyde. This designed transformation occurs under aerobic conditions and provides a series of bio-inspired molecular scaffolds. In addition, photophysical studies showed blue fluorescence emission with a good fluorescence quantum yield.