Carbonyl and thiocarbonyl compounds. XIX. Intramolecular cyclization of (2-nitroetheny1)aryl N-arylcarbamates : synthesis of newer series of 3,4-dihydro-2H-1,3-oxazin-2-ones and their antimicrobial activities

Abstract

The hitherto unknown 2-(2-nitroethenyl)aryl and 1-(2-nitroethenyl)naphthalen-2-yl N-arylcarbamates (2) and (5) are readily obtained through the uncatalysed interaction of aryl isocyanates with the corresponding 2-nitroethenyl phenols (1) and (4). The carbamates (2) and (5) cyclize readily at ambient temperature under base catalysis to the corresponding 3-aryl-4-nitromethyl-3,4-dihydro-2H-1,3-benzoxazin-2-ones (3) and 2-aryl-1-nitromethyl-2,3-dihydro-1H-naphth[l,2-e][1,3]oxazin-3-ones (6). The oxazinones (3) are cleaved by hot pyridine affording the corresponding 2-(2-nitroethenyl)phenols and N,N'-diarylurea, whereas, with butylamine, the corresponding aryl(butyl)urea and salicylaldehyde are obtained. The antimicrobial properties of the carbamates and benzoxazinones are evaluated.