METHYLBENZOTHIAZOLE

Related Reagents. Methallyl chloride Methallyl Bromide Methallyl Alcohol 3-Chloro-2-chloromethyl-l-propene 2-Methylene-1,3-propanediol. 

Solubility insol H2O sol ethanol very sol diethyl ether, THF. Form Supplied in liquid widely available. 

Handling, Storage, and Precautions should be freshly distilled before use for best results. Toxic by inhalation, in contact with skin, and if swallowed. Use in a fume hood. 

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). 

Chikashita et al. have demonstrated the synthetic equivalence of (3) to a masked enolate anion through the liberation of the aldehyde by cleavage of the benzothiazole ring (eq 4). 

Analysis of Reagent Purity H and NMR spectra. Purification distillation under reduced pressure. 

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). 

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A heterocyclic ring induces partial double-bond fixation in a fused benzene ring. Hence, for example, diazo coupling occurs at the 7-position of 6-hydroxyindazole (349), and Claisen rearrangement of 6-allyloxy-2-methylbenzothiazole (350) gives the 7- and 5-allyl products in a ratio of 20 1. 

The first thiazoloquinolines, namely angularly annelated 2-methyl-thiazolo [4,5-/]quinoline 19 and linearly annelated 2-methyl-thiazolo[4,5-g]quinoline 20, were prepared in 1937 in poor yield using the Skraup reaction and exploiting the blockage of position 4 in 5-amino-2-methylbenzothiazole with a chlorine atom, as shown in Scheme 10 (37LA60). 

A dicarbocyanine dye, dithiazinine (79), is used as a broad-spectrum anthelmentic agent, although, interestingly, it seems to have been prepared initially for use in photographic emulsions. It is made by heating 2-methylbenzothiazole ethiodide (77) with the malondialdehyde equivalent, B(ethylmercapto)-acrolein diethylacetal (78) in the presence of pyridine. There apparently ensues a sequence of addition-elimination reactions quenching the reaction mixture with potassium iodide solution results in separation of green crystals of dithiazanine iodide (79). ... 

Other methylketones and differently activated methyl compounds can also be used to synthesize formazanes in the same manner, as was shown, for example, in early work by Wahl and Lebris (1954) on the coupling with 2-methylbenzothiazole (Scheme 12-39). 

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. 

Similar studies of the relationship between bond structures and the Claisen rearrangement have been made with allyloxy derivatives of other aromatic compounds, among them anthracene,60 phenanthrene,61 hy-drindene,62 fluorene,68 chromone,64 flavone,64 fluorenone,66 and 2-methylbenzothiazole.660... 

Table 3 UV Absorption Spectra (alcohol) of Benzothiazole and 2-Methylbenzothiazole...

Benzothiazole and 2-methylbenzothiazole form with diborane a 1 1 adduct which rearranges into A-substituted benzothiazaborole (Scheme 14) (78CC971). 

Chlorination of 2-methylbenzothiazole occurs when this compound reacts with chlorine gas at 80 °C in acetic acid-sodium acetate solution. The hydrolysis of the 2-trichloromethyl derivative thus formed gives 2-benzothiazolecarboxylic acid. 

Bisbenzothiazolylalkanes could be obtained by cyclization of o-aminothiophenol with aromatic and certain aliphatic diacids. Acetic anhydride is used to obtain the most important 2-methylbenzothiazole. The reaction of an o-aminothiophenol with phosgene, and with thiophosgene or carbon disulfide, gives a 2-hydroxy- and a 2-mercapto-benzothiazole, respectively, o-Aminothiophenol adds to alkynecarbonitriles (514) forming vinylamines... 

The proton chemical shifts of the CH3-group in 2-methylbenzothiazoles (including nitro derivatives) were compared with charges (q) on the C-2 calculated by the PPP method [782],... 

The reaction of butyltin trichloride with l-(2-methyl-2,3-dihydrobenzotriazol-2-yl)-propan-2-one gives an organotin complex that was formulated as containing the [BuSn(OH)Cl3]2 anion " . However, a reinvestigation of the crystal structure of this complex reveals a neutral hydroxyl-bridged aqua-butyldichlorotin hydroxide dimer that is linked to four 2-methylbenzothiazole molecules by short hydrogen bonds " . 

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