Benzothiadiazoles synthesis

Zhang S, Guo Y, Fan H, Liu Y, Chen H-Y, Yang G, Zhan X, Liu Y, Li Y, Yang Y (2009) Low bandgap pi-conjugated copolymers based on fused thiophenes and benzothiadiazole synthesis and structure-property relationship study. J Polym Sci A Polym Chem 47 5498... 

Amino-2,l,3-benzothiadiazole treated under similar conditions afforded, re-gioselectively, an analogous angularly annelated ester 68 and acid 69, both to be tested for inhibition of the DNA synthesis (74MI1). Subsequent alkylation of the... 

Compounds of special interest whose preparation is described include 1,2,3-benzothiadiazole 1,1-dioxide (a benzyne precursor under exceptionally mild conditions), bis(l,3-diphenylimida-zolidinylidene-2) (whose chemistry is quite remarkable), 6- di-melhylamino)julvene (a useful intermediate for fused-ring non-benzenoid aromatic compounds), dipkenylcyclopropenone (the synthesis of which is a milestone in theoretical organic chemistry), ketene di(2-melhoxyethyl) acetal (the easiest ketene acetal to prepare), 2-methylcyclopenlane-l,3-dione (a useful intermediate in steroid synthesis), and 2-phenyl-5-oxazolone (an important intermediate in amino acid chemistry). 

Benzothiadiazole 3, when heated in the presence of sulfur, first loses nitrogen and then reacts with sulfur to form benzopentathiepin 32 C1984JOC1221 >. This method has been extended to the synthesis of several heterocyclic ring compounds fused to pentathiepin starting from the corresponding 1,2,3-thiadiazolo heterocycle (Equation 4) <1985JA3871>. 

Q. Hou, Q. Zhou, Y. Zhang, W. Yang, R. Yang, and Y. Cao, Synthesis and electroluminescent properties of high-efficiency saturated red emitter based on copolymers from fluorene and 4,7-di(4-hexylthien- 2-yl)-2,l,3-benzothiadiazole, Macromolecules, 37 6299-6305, 2004. 

The syntheses from [4+1] atom fragments, in which the Group 16 heteroatom is introduced between two nitrogen atoms, are the most widely applicable and versatile methods available for construction of the 1,2,5-thiadiazole ring system. These methods have been applied to the synthesis of monocyclic and polycyclic aromatic forms of these ring systems in addition to the direct formation of 1-oxides and 1,1-dioxides, 2-oxides, quaternary salts, and reduced forms. The earliest use of the [4+ 1] synthesis dates back to 1889 when Hinsburg prepared 2,1,3-benzothiadiazole (I) from o-phenylenediamine and sodium bisulfite. 

For almost a century, since 2,1,3-benzothiadiazole (1) was discovered by Hinsburg in 1889, the chemistry of 1,2,5-thia- and -selena-diazoles has held considerable interest for organic and physical chemists. Three periods of progress can be distinguished during the first, 1890-1958, interest focused on the synthesis and substitution of benzo derivatives (1)... 

Freis and Reitz, using potassium nitrate in sulfuric acid on heating, have obtained two mononitrated products and assigned to them the structures of 4- and 7-nitro isomers [212], Later, this structure has been proved by a secondary synthesis [213], and the other isomer turned out to be 5-nitro-l,2,3-benzothiadiazole [214, 215], On a more careful study all three isomers were found among the reaction products, as shown in Scheme 2.18 [216],... 

Substituted 1,2,3-benzothiadiazoles are nitrated to the position 5 or 7 if they are vacant [197, 217-219], The data [218] on the synthesis of 4-nitro-substituted 1,2,3-benzothiadiazoles need to be checked. 

The synthesis, structure, and superoxide dismutase mimetic activity in vitro and the protection against reactive oxygen species in vivo of mononuclear copper complexes with 2-(4-methylphenylsulfamoyl)-6-nitrobenzothiazole have been reported [602], Like 1,2,3-benzoxadiazoles, nitroderivatives of 1,2,3-benzothiadiazoles were obtained on diazotization of the corresponding or/Zzo-aminothiophcnolcs [213, 218, 583], The initial or/Zzo-thiophcnols for this reaction were synthesized by nucleophilic substitution of halogen in ort/zo-halogenoanilines. It turned out that 4-nitro- and... 

A large body of information on the methods of synthesis, application, structure, and properties of all known five-membered nitroazoles - pyrazoles, imidazoles, triazoles, tetrazoles, oxazoles, isoxazoles, oxadiazoles, thiazoles, isothiazoles, thiadiazoles, selenazoles, selenadiazoles, and their benzo analogs - indazoles, benzimidazoles, benzoxazoles, benzisoxazoles, benzoxadiazoles, benzothiazoles, benzoisothiazoles, benzothiadiazoles, benzotriazoles, benzoselenazoles, and ben-zoselenadiazoles has been systematized, summarized, and critically discussed in this monograph. 

The diazotization of aromatic amines witii a nucleophilic substituent at the ortho position is a common mediod of synthesis of benzo-fosed heterocyclic compounds with two or more contiguous nitrogen atoms. Benzotriazoles (9), benzotriazinones (10), and benzothiadiazoles (11) are examples of heterocyclic ring systems that can be prepared in tiiis way. 

The synthesis of 1,2,5-thiadiazoles from a-diamines was studied as early as 1897 when Michaelis attempted the preparation of the parent compound by reaction of ethylenediamine with sulfur dioxide. The product, however, was bissulfimic acid (28) which readily lost sulfur dioxide to form the betaine (28a). Later Shew reported that 3,4-dicyano-l,2,5-thiadiazole (30) results from the reaction of cis-diaminomaleonitrile (29, HCN tetramer) with thionyl chloride, a reaction which is analogous to 2,1,3-benzothiadiazole formation from o-phenylenediamines. The synthesis of the parent 1,2,5-thiadiazole and some alkyl analogs (32) was accomplished by reaction of salts of... 

Yamamoto, T., Fang, Q., and Morikila, T. 2003. New soluble poly(aryleneethynylene)s consisting of electron-accepting benzothiadiazole units and electron-donating dialkoxybenzene units. Synthesis, molecular assembly, orientation on substrates, and electrochemical and optical properties. Macromolecules 36,4262-4267. 

This phytoalexin helps the plant resist attack by gray mold (Botrytis cinerea). Another possibility is to use a phytoalexin made by a chemical synthesis apart from the plant. Novartis sells a benzothiadiazole (Actigard) that elicits systemic resistance to bacterial and fungal pathogens.189... 

Benzothiadiazoles and 2,1,3-Benzoselenadiazoles. - Biologically active substances among benzo-2,l,3-thiadiazole derivatives have been reviewed, with 83 references. The synthesis of 4-bromobenzo-2,l,3-thiadiazole-7-... 

Dithians. - A new synthesis of thianthrene and its symmetrically substituted derivatives has been described in which a 1,23-benzothiadiazole (262) is heated in benzene that contains di-t-butyl peroxidel-(3-Chloroethyl-... 

A new synthesis of lH,3/f-2,l,3-benzothiadiazole-2,2-dioxide has been reported by Acheson and collaborators370. The reaction of N,N -dibenzyl-1,2-diaminobenzene (383) with thionyl chloride (equation 127) gives the l,3-dibenzyl-lH,3//-2,l,3-benzothiadiazole-2-oxide (384) which, on oxidation with m-chloroperbenzoic acid, yields the iV,iV -dibenzylated thiadiazole-2,2-dioxide (385). Debenzylation of 385 leads to the parent thiadiazole-2,2-dioxide (386), which heretofore was not readily synthesized. 

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