Synthesis of 5-alkyl(or aryl)pyrrolo[1,2-a]quinoxalin-4(5H)-ones by denitrocyclisation of N-alkyl(or aryl)-1-(2-nitrophenyl)-1H-pyrrole-2-carboxamides. Evidence of a Smiles rearrangement

An efficient method for the synthesis of hitherto unknown alkyl(or aryl)pyrrolo[1,2-a]quinoxalin-4(5H)-ones , and has been established. The method is based on the synthesis of the corresponding N-alkyl(or aryl)-1-(2-nitrophenyl)-1H-pyrrole-2-carboxamides and which undergo denitrocyclisation with NaH in DMF in 4.5 or 2 h. When was treated with NaH in DMF for 30 min the product of a Smiles rearrangement, , was isolated. Under similar conditions but for 4.5 h was converted into . This confirms the involvement of a Smiles rearrangement during the denitrocyclisation process. Conversion of into isomeric pyrroloquinoxalinones and confirms a process involving two pathways, direct denitrocylisation of and Smiles rearrangement of followed by denitrocylisation, respectively. Furthermore, denitrocylisation of into pyrroloquinoxalinones and suggests that similar cyclisation pathways are followed by N-arylcarboxamides.