Ketones 2- benzothiazole synthesis

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>. 

Similarly, MyllymSki et al. have employed this concept in the synthesis of aryl ketones via the reaction of the lithio benzothiazole with an aryl acid chloride to produce the desired ketone. A series of such carbonyl compounds was synthesized and evaluated as potential fatty acid amide hydrolase (FAAH) inhibitors. 

Methods for derivatization of aldehydes and ketones using preformed Mannich reagents have been summarized.2-(Morpholinothio)benzothiazole (55) is a key reagent in a synthesis of 2-substituted cyclopentenones from the cyclo-pentanone (Scheme 47). 

The synthesis of fluoroalkene derivatives has recently been disclosed using 2-(l-fluoroethyl)sulfonyl-l,3-benzothiazole in the presence of various aldehydes and ketones. Either NaHMDS or t-BuOK could be used as a base. 

Chikashita, H. Ishihara, M. Takigawa, K Itoh, K. (1991). Synthetic ap>phcation of benzothiazole ring system as an on-off type of leaving group. Synthesis of ketones and carboxylic acid derivatives from 2-(l-substituted 1-hydroxyalkyl)- and 2-(l-hydroxyalkyl)benzothiazoles. Bidl. Chem. Soc. Jpn. Vol. 64, pp. 3256-3261, ISSN. 

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