Benzothiazole, 2-chloro-, reaction with

When two polymers interact or react with each other, they are likely to provide a compatible, even a miscible, blend. Epoxidized natural rubber (ENR) interacts with chloro-sulfonated polyethylene (Hypalon) and polyvinyl chloride (PVC) forming partially miscible and miscible blends, respectively, due to the reaction between chlorosulfonic acid group and chlorine with epoxy group of ENR. Chiu et al. have studied the blends of chlorinated polyethylene (CR) with ENR at blend ratios of 75 25, 50 50, and 25 75, as well as pure rubbers using sulfur (Sg), 2-mercapto-benzothiazole, and 2-benzothiazole disulfide as vulcanizing agents [32]. They have studied Mooney viscosity, scorch... 

There are several new methodologies based on the Julia olefination reaction. For example, 2-(benzo[t/Jthiazol-2-ylsulfonyl)-j -methoxy-i -methylacetamide 178, prepared in two steps from 2-chloro-iV-methoxy-jV-methylacetamide, reacts with a variety of aldehydes in the presence of sodium hydride to furnish the ajl-unsaturated Weinreb amides 179 <06EJOC2851>. An efficient synthesis of fluorinated olefins 182 features the Julia olefination of aldehydes or ketones with a-fluoro l,3-benzothiazol-2-yl sulfones 181, readily available from l,3-benzothiazol-2-yl sulfones 180 via electrophilic fluorination <06OL1553>. A similar strategy has been applied to the synthesis of a-fluoro acrylates 185 <06OL4457>. 

In contrast, thiazoles and benzothiazoles are suitable recipients for the heteroaryl Heck reaction. Treatment of 2-chloro-3,6-diisobutylpyrazine (103) with thiazole led to regioselective addition at C(5), giving rise to adduct 104 [57]. A similar reaction between 2-chloro-3,6-diethylpyrazine (105) and benzo[ >]thiazole took place at C(2) exclusively to afford pyrazinylbenzothiazole 106 [57]. 

Cyclic amidines (213) react with chlorocarbonylsulfenyl chloride to give bicyclic 1,2,4-thia-diazoles. The product isolated from this reaction depends on the mode of addition. When (213) is added to chlorocarbonylsulfenyl chloride, 3-oxo derivatives (214) are isolated via the postulated intermediate (215). Addition of chlorocarbonylsulfenyl chloride to (213) leads to 5-oxo derivatives (216), via the proposed bis(intermediate) (217) (Scheme 47) <84CHEC-I(6)463). Cyclic amidines (213) have also been treated with 1-chloro-l-phenyliminomethanesulfenyl chloride (210) to afford 2>H-1,2,4-thiadiazoles (218). The other possible product from this reaction, the 2/7-isomer (219) has been shown to be unstable, rearranging to a benzothiazole. Heterocycles (213) which have been used in this transformation include 2-aminopyridine, 3-aminopyridazine, 2-aminobenzothiazole, 2-aminopyrimidine and 2-aminothiazole (Equation (33)) <86S1027>. 

A highly regioselective microwave promoted synthesis of 2-aryl-6-chloro-benzothiazoles (xxxviii) by the Suzuki-Miyaura coupling reaction of 2,6-dic-hlorobenzothiazole with arylboronic acids is given by Heo et al. [58]. 

There is an early report that thiophene reacts at the 3-position in phenylation with benzenediazonium chloride and aluminum trichloride,8 but in the Gomberg reaction thiophene has been found to substitute mainly at the 2-position both with p-tolyl and with p-chloro-phenyl radicals.04 Benzothiazole is phenylated at the 2-position in low yield by dibenzoyl peroxide a small quantity of the 4-isomer is also obtained.24... 

One of the most studied microwave-assisted formations of the benzothiazole ring is initiated by an addition-elimination reaction. Treatment of aniline derivatives with 4,5-dichloro-l,2,3-dithiazolium chloride (commonly called Appel s salt) gave 4-chloro-5]-f-l,2,3-iminodithiazoles (47) which are very versatile intermediates in the synthesis of a variety of heterocycles (Scheme 9.15). Besson and coworkers... 

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