7- Arylthio-4-nitro

Einen bemerkenswerten Verlauf nimmt die Oxidation von 7-Arylthio-4-nitro-benzofurazan-1-oxid351 mit 3-Chlor-perbenzoesaure. Man erhalt zunachst ein Sulfoxid, das sich thermisch (Erwarmen in Eisessig, Acetanhydrid bzw. Toluol) unter Sauerstoff-Verschiebung zu 4-Aryl-sulfonyl-7-nitro-benzofurazanen umlagert352 ... 

As seen, the direct snbstitntion of the arylthio moiety for chlorine is observed only for the 4-nitro derivatives. The optically active snbstrate gives the racemic snbstitntion product on the reaction with phenylthiolate ion (Scheme 7.71). 

Haufig verwendet wird die Oxidation der 4- bzw. 5-Alkylthio- oder Arylthio-Verbindungen von 5- bzw. 4-Nitro-imidazolen1061"1063 mit Wasserstoffperoxid in Essigsaure zu den entspre-chenden Sulfonen, da diese Verbindungsklasse auf dem Wirkstoffsektor von Interesse ist. 

A variety of substituted 3-aminobenzo[6]thiophenes have been obtained by ring closure reactions of nitriles (equation 57). Various o -cyanophenylthioacetyl derivatives, when treated with base, yield the 3-amino derivatives (Section 3.15.2.2.3). The benzonitriles may be obtained by displacement of the o-nitro group from o -nitrobenzonitriles (74JOC3440). 2-Arylthio-l-chloroenamines are cyclized to 3 -dialkylaminobenzo[6]thiophenes in the presence of Lewis acid catalysts (equation 58). The 1 -chloroenamines may be prepared from t-amides or ynamines <8lH(15)l 179>. 

The Komblum reactions at the tertiary carbon atoms also belong to the dark SrnI substitutions. Let us compare the reactions of a-cumyl chloride and 4-nitro-a-cumyl chloride with the phenylthiolate ion (Komblum 1975) (Scheme 8-8). As seen, the substitution of the arylthio moiety for chlorine at the former position of the chlorine is observed only for the 4-nitroderivative. The optically active substrate gives the racemic substitution product upon reaction with the phenylthiolate ion (Scheme 8-9). 

Finally, a novel three-component radical cascade reaction involving isonitriles has just been published [6]. In this paper, aromatic disulfides, alkynes, and isonitriles have been reported to react under photolytic conditions to afford -arylthio-substituted acrylamides 49 or acrylonitriles 50 in fair yields as mixtures of the E and Z geometric isomers (Scheme 21). The procedure entails addition of a sulfanyl radical to the alkyne followed by attack of the resulting vinyl radical on the isonitrile. A fast reaction, for example, scavenging by a nitro-derivative (route a) or f-fragmentation (route b), is necessary in order to trap the final imidoyl radical, since addition of vinyl radicals to isonitriles seems to be a reversible process. The reaction provides very easy access to potentially useful poly-functionalized alkenes through a very selective tandem addition sequence. 

Nucleophilic c/ne-substitution Partial replacement of nitro by arylthio groups... 

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