Tailored Aza-Michael Addition as Key Step in the Synthesis of 1H-imidazo[5,1-c][1,4]oxazine Scaffolds

A novel protocol for the efficient synthesis of 1H-imidazo[5,1-c][1,4]oxazines has been developed. Aza-Michael addition of selected primary amines to 1,2-diaza-1,3-dienes (DDs) combined with isothiocyanates or isocyanates in sequential 3-CR process, affords 2-thiohydantoins and hydantoins with suitably positioned functional groups to be used for chemoselective acid-promoted ring-fused formation.

Automated summary

A novel protocol for the efficient synthesis of 1H-imidazo[5,1-c][1,4]oxazines has been developed by combining aza-Michael addition of selected primary amines to 1,2-diaza-1,3-dienes (DDs) with isothiocyanates or isocyanates in a sequential 3-component reaction (3-CR) process, resulting in 2-thiohydantoins and hydantoins with suitably positioned functional groups for chemoselective acid-promoted ring-fused formation.