Hydrazines Vilsmeier-Haack reaction

The Vilsmeier-Haack reaction of the benzazepinone 306 gives the en-aminone 307, which, upon treatment with 4-chlorophenyl hydrazine, gives the pyrazole 308. Pyrazolothiazines and pyrazolo-[4,3-6][l,4]-benzothia zines were similarly prepared (72CPB1325). 

Reactions of Other Derivatives.—Condensation of 2-methyl-benzothiazoles with aromatic aldehydes may be carried out in 50% aqueous sodium hydroxide at room temperature in the presence of triethylbenzylammonium chloride. In some cases the intermediate carbinols are isolable under these conditions. 2-Methylbenzothiazoles undergo the Vilsmeier-Haack reaction to give products [1 R = C( CHOH)CHO] that can be converted into other heterocycles e.g., alkyl- or aryl-hydrazines furnish pyrazoles. ... 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

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