Aldehydes 2-methylbenzothiazole

Dryanska and Ivanov175 have condensed 2-methylbenzoxazole and 2-methylbenzothiazole (111) with an aryl aldehyde to yield the corresponding substituted styrene derivative 112. Depending on conditions, the intermediate carbinol has been isolated. 

Different colorimetric methods have been developed for the determination of aldehyde and diketone contents in alcoholic beverages. Fuchsin, piperidine, 3-methylbenzothiazole-2-one hydrazone, 2-naphtol, and creatine have generally been used as reagents to produce colored compounds, the absorbances of which are measured at a wavelength between 630 and 660 nm or 500 and 550 nm. 

Introduction. 2-Methylbenzothiazole (1) has been used in base- and acid-mediated condensations with aldehydes to give products which normally undergo dehydration in situ to give alkenes (2) (eq 1). 

Q -Lithio-2-methylbenzothiazole (3) reacts with various electrophiles such as aldehydes and ketones to afford 2-(2-hydroxyalkyl)benzothiazoles in high yields (eq 3). 

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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