An efficient synthesis of furyl sulfonamides from the reaction of furan with in situ generated N-tosyl imines

Treatment of an aldehyde and furan with N-sulfinyl-p-toluenesulfonamide/zinc chloride leads to the formation of furyl sulfonamides via an in situ generated N-tosyl imine intermediate. In one case, a novel 4-tosylamino-5,6-dihydro-4H-3-oxa-benze]azulene was obtained by intramolecular aromatic substitution of the activated imine at the 3-position of the furan ring.