Isothiazoles, acetyl

Friedel-Crafts acylation usually fails (72AHC(14)43), but 3-substituted l-methyl-2,1-benzisothiazole 2,2-dioxides can be acetylated at the 5-position (73JHC249). l-Methyl-2,1-benzisothiazol-3-one can be chlorsulfonated at the 5-position (78JHC529). Vilsmeier-Haack formylation causes cleavage of the isothiazole ring (80JCR(S)197). 

Isothiazole, 5-acetamido-3-alkyl-nitrosation, 5, 59 6, 148 Isothiazole, 5-acetyl-thiosemicarbazone biological activity, 6, 175 Isothiazole, 4-acetyl-5-amino-3-bromo-synthesis, 6, 166 Isothiazole, 4-acetyl-3-methyl-oxime... 

Formyl- and 4-bromo-3-formyl-isothiazole have been prepared in good yield from the dibromomethyl compounds obtained by side-chain halogenation of the appropriate 3-methylisothiazole with N-bromosuccinimide. 3-Acetyl- and 3-acetyl-4-bromo-isothiazole have been prepared from the 3-cyanoisothiazoles and methyl magnesium iodide. ... 

Thiosemicarbazones of 5-formyl- and 5-acetyl-isothiazoles are riBported to have high activity against the pox group of viruses. ... 

Acetyl- and 5-formylisothiazoles are readily available from 5-lithioisothiazoles.71,102 However, 3-methyl-4-nitroisothiazole does not form a lithium derivative,72 and 4-formyl-3-methyl-4-nitro-isothiazole was prepared by reduction of the appropriate acid chloride with lithium tri-Lbutoxyaluminum hydride.140 A 5-formyl-4-hydroxy-isothiazole has been prepared by direct ring synthesis [Eq. (12)].29... 

N-Acyl saccharins (13) in part resemble iV-alkyl saccharins in their reactions. From the hydrolysis of 3-oxo-2-acetyl-6-chloro-2,3-dihydro-benz[d]isothiazole-1,1-dioxide (64) with a base/alcohol mixture one obtains iV-acetyl-4-chloro-2-sulfamoylbenzoic acid (65). On heating with base the acetyl group is hydrolyzed off.180... 

Pyrazole, isothiazole and isoxazole undergo straightforward nitration, at C. With acetyl nitrate or dinitrogen tetraoxide/ozone, 1-nitropyrazole is formed, but this can be rearranged to 4-nitropyrazole in acid at low temperature. ... 

Amino-1,2-azoles exist as the amino tautomers. Amino-pyrazoles and amino-isothiazoles are relatively well-behaved aromatic amines, for example 3(5)-aminopyrazole undergoes substituent-A-acetylation and easy electrophilic bromination at C-4. Diazotisation and a subsequent Sandmeyer reaction provides routes to halo-isothiazoles and azido-pyrazoles. ... 

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