o-Nitroaryl-bis(5-methylfur-2-yl)methanes as Versatile Synthons for the Synthesis of Nitrogen-Containing Heterocycles

o-Nitroaryl-bis(5-methylfur-2-yl)methanes as Versatile Synthons for the Synthesis of Nitrogen-Containing Heterocycles

Blog Article

2-Nitroaryldifurylmethanes 1a and 1b, readily available by condensation of 2-nitrobenzaldehyde and 6-nitroveratraldehyde with 2-methylfuran, were transformed into indole, cinnoline and sauceland benzothiazine-3,1 derivatives.The reduction of 2-nitroaryldifurylmethanes gave the corresponding anilines 2a,b or indole 3 depending on the reaction conditions.A plausible mechanism for the last reaction involving intramolecular heterocyclic addition between a nitroso-group and a furan ring is proposed.Diazotisation of the amine 2b gave a cinnoline derivative - a product of intramolecular oxidative furan ring opening.Treatment of isothiocyanates 7a,b with perchloric acid resulted in a new rearrangement with furan ring migration leading ad24ce to the 4-Hbenzothiazine-3,1 derivatives.