2.1- Benzisothiazoles, nitration

Nitration of 1,2-benzisothiazole gives equal quantities of the 5- and 7-nitro compounds (72AHC(14)43> (see Section 4.02.3.2), as also do the 3-methyl (71JCS(C)3994, 80JCR(2)197> and... 

Benzisothiazole, 4-chloro-nitration, 6, 154 nucleophilic reactions, 6, 154 synthesis, 6, 169... 

Ricci and co-workers28 found that nitrogen of 1,2-benzisothiazole (1) with potassium nitrate and sulfuric acid at 0° afforded a mixture of the 5-nitro compound (28) and the 7-nitro derivative (29). The... 

No simple salts of 2,1 -benzisothiazole have been described in the literature, other than those of amino-substituted derivatives,101 in which the site of protonation is probably the cyclic nitrogen atom, at least in the 3-substituted compounds. The parent compound does, however, form a simple crystalline nitrate 114 which is not very stable. A number of complex salts with platinum, gold, lead, and mercury salts and with picric acid have been described.96,97,116 The picrate is highly crystalline and stable, and is useful for the isolation and characterization of 2,1-benzisothiazole. Many substituted 2,1-benzisothiazoles form similarly useful picrates.106... 

The introduction of substituents into the position 3 does not change the reaction course [165, 167-169], 4-Amino-7-nitrobenzisothiazole in the sulfuric-nitric mixture forms 5,7-dinitro derivative in low yield [170], 4-Chloro-7-nitro-l,2-benzisothiazole was obtained as a result of the nitration of 4-chloro-l,2-benzisothiazole [171,172], 5-Hydroxy-l,2-benzothiazole is nitrated to the position 4, and in case of 5-hydroxy-4,6-dibromo-l,2-benzisothiazole a substitutive nitration to form 5-hydroxy-6-bromo-4-nitro isomer occurs [173],... 

The main product of the nitration of 2,1-benzisothiazole (thioanthranil) is 5-nitro-2,l-benzisothiazole (57%) however, alongside significant amounts of other isomers such as 7-nitro- (26%) and 4-nitro-2,l-benzisothiazole (17%) are formed [174], The nitration of several other substituted thioanthranils has also been carried out [128, 174-176],... 

The data on the synthesis of nitrated 2,1-benzisothiazoles are rather scarce in comparison with the corresponding benzisoxazoles. It has been reported that, like other 2-aminotoluenes, 2-amino-4-nitrotoluene reacts with thionyle chloride in xylene to form 6-nitro-2,l-benzisothiazole, whereas 2-amino-5-nitrotoluene does not enter into this reaction (Scheme 2.93) [543],... 

Only a few examples of NMR investigation of nitrated 1,2-benzisothiazoles are known. 3-Substituted 4,6-dinitro- 1,2-benzisothiazoles, 2-substituted 4,6-dini-tro-l,2-benzisothiazol-3-ones and their oxides obtained using highly efficient technology for conversion of 2,4,6-trinitrotoluene have been identified by II NMR spectra [784],... 

The oxidation of 2-alkyl-2,3-dihydro-1,2-benzisothiazole with peracetic acid affords the 1,1-dioxide <86TL5703>. The nitration of 2,3-dihydro-3,3-dimethyl-l,2-benzisothiazole 1,1-dioxide (148) (Y = H) yields the A -nitro-7-nitro compound, which with sulfuric acid produces the 7-nitro derivative <92T1595>. 2,3-Dihydro-2,l-benzisothiazole 1,1-dioxide on nitration gives the 5,7-dinitro derivative, while the 1-ethoxycarbonyl analog yields the 5-nitro compound <86JHC1645>. 

The nitration of 3,5-dimethyl-1,2-benzisothiazole to the 4-nitro and 7-nitro products has been described <91JHC347>. Friedel rafts acylation of 3-methyl-6-methylthio-1,2-benzisothiazole gives the 7-acetyl derivative whereas the 5-methylthio analog fails to acylate <91JHC445>. 

The treatment of a disulfide with ammonia, silver nitrate, and a ketone is a general one-step synthesis of sulfenimines.13 The disulfide 5, in an intramolecular reaction, affords13 the 1,2-benzisothiazole 6. 

Benzisothiazole undergoes nitration at its 5- and 7-positions.1 Electrophilic substitution of 3-methyl-1,2-benzisothiazole (2) and its 5-amino, 5-... 

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