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.
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.
5-(2-Nitroethenyl)salicyloyl chloride (2 b) condenses with anilines affording the anilides 3a-h. The compound 3a reacts with isocyanates to give the corresponding carbarnates 5a-c, whereas at higher temperatures the anilide 3a as well as the acid 2a give the same benzoxazinedione 4 a which affords 5-formyl-N-methylsalicylamide (6) upon treatment with alkali. 3a and 3d react with thionyl chloride to give the corresponding 2-chloro-5-(2-nitroetheny1)benzanilides 8a and 8b. Spectral features of the compounds are discussed and their molluscicidal and microbicidal activities are presented. Mit Thionylchlorid reagieren 3a und 3d zu den entspechenden 2-Chlor-5-(2-nitroethenyl)-benzaniliden 8 a bzw. 8 b. Die spektroskopischen Merkmale der Verbindungen werden diskutiert, und iiber die molluskiziden und mikrobiziden Eigenschaften wird berichtet.Several synthetic organic compounds proved to be toxic to aquatic snails and some of these compounds are now used as molluscicides in prevention of parasitic diseases. An important group of molluscicides are the salicylanilides, the most active member of which turned out to be 2',5-dichloro-4'-nitrosalicylanilide (1) which is now used successfully in combating snails for control of schistosomiasis in endemic areas1). On the other hand, it has been shown in our laboratory that some aryl-and heteroaryl-substituted nitroalkenes possess molluscicidal properties characterized by a well defined knock-down effect".In the light of the aforementioned reports and in the course of our program in search of new molluscicides, it was interesting to construct molecules incorporating both the salicylanilide and nitroethenyl moieties in an attempt to obtain compounds which possibly would combine the biological properties of both or synergize any of these activities.For this purpose, 5-formylsalicylic acid was condensed with nitromethane in acetic acid in the presence of n-butylamine'), to give 5-(2-nitroethenyl)salicylic * ) This procedure proved to be superior to that previously described using ammonium 0 VCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1985 acetate in acetic acid3'.
o‐Phenylendiamin (I) setzt sich mit den Arylaldehyden (II) bei niedriger Temp. zu den Monoanilen (III) um, während in siedendem Ethanol mit (IIa) die Benzimidazole (IVa) zusammen mit den entsprechenden Dianilen, mit (IIb) dagegen ausschließlich die Benzimidazole (VIb) gebildet werden.
Reaktionen der Titelverbindungen (II) mit p‐Aminobenzoesäureethylester liefern in hohen Ausb. die Chinazolinthione (I), daneben das Brenzcatechin (VI); bei Umsetzungen mit Malodinitril bzw. Cyanessigester in Ethanol erhält man die Benzothiazine (III) (Mechanismus) in Gemischen mit Aminobenzoaten des Typs (V) sowie (VI).
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