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.
New 2H-Benz[g]indazoles of Anticipated Molluscicidal Activity. -Title compounds, e.g. (III) and (V), show remarkable molluscicidal activity. -(MISHRIKY, N.; IBRAHIM, Y. A.; GIRGIS, A. S.; FAWZY, N. G.; Pharmazie 54 (1999)
The nature of the products of the uncatalysed reaction of the o‐hydroxybenzaldehydes 1a‐d with o‐phenylenediamine in boiling ethanol is mainly dependent on the molar ratio of the reactants and the nature of the substituents at the phenyl ring of the aldehyde. In contrast, the m‐ and p‐hydroxy analogues 1e‐g afford exclusively the corresponding 1‐aralkyl‐2‐arylbenzimidazoles 6, regardless of these factors. However, at low temperature, the hydroxybenzaldehydes 1a‐g react with the diamine always giving monoanils (2) regardless of the hydroxy position. The monoanils of the o‐hydroxy aldehydes afford predominantly 2‐arylbenzimidazoles (4) when boiled in n‐butanol. In contrast, those of the m‐ and p‐hydroxy analogues give exclusively 1‐aralkyl‐2‐arylbenzimidazoles (6), whereas, when heated in nitrobenzene, 2‐arylbenzimidazoles (4) are readily obtained. The dianils 5a‐d, upon boiling in butanol, give a mixture of 2‐arylbenzimidazoles (4) and 1‐aralkyl‐2‐arylbenzimidazoles (6), the ratio of which is dependent on the nature of the substituents at the aldehyde. Reaction mechanisms and spectral features of the products are discussed.
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