3-Isothiazolone ring

Substances containing an isothiazolone ring, such as 2-methyl-isothiazolin-3-one (MI), benzisothiazolin-3-one (BIT), 2-methyl-4,5-trimethylene-isothiazolin-3-one, also contain activated N-S bonds which may react with nucleophilic cell entities with opening of the isothiazolone ring, thus exerting antimicrobial activity (Miller et ah, 1975). 

Many analogues of saccharin have been synthesized since its discovery. With the exception of one compound, thieno[3,4-i/ isothiazolone dioxide [59337-79-0] lOOOX, this effort has not generated more potent compounds. Acesulfame-K could be considered a ring-modification derivative of saccharin, however. 

Isothiazolone dioxide rings are readily cleaved in diluted aqueous alkaline solution at r.t. and this feature allows their use, in some cases, as a protecting group (95TL(36)6227). An example is the efficient Fischer indole synthesis of 72. 

Single coordination units are found where the O ligands are large, as in Ph3SnLL 144 for L = diphenylcyclopropenone and L an isothiazolone or the similar saccharine. OSnO is near-linear and CSnC adjust to steric factors in the range 114-134°, SnO(ketone) = 237-241 pm, Sn-O(hetero-ring) = 216 pm, Sn-C = 211-216 pm. 

The syntheses of 2,3-dihydro-TAs are the least developed. A few reactions are based on the ring enlargement of isothiazolones. The rearrange-... 

Formation of the C - N bond through a cychsation process is the key step for the synthesis of the isothiazolone S,S-oxide ring 158 from the corresponding 157 according to Method /, which is also general for dihydroderivatives and for benzisothiazolones [1,2]. 

Dihydro-2/f-l,3-thiazin-4-ones (313) are available through the ring expansion of 2-substituted isothiazolones (314) with dimethyl diazomalonate in the presence of rhodium(II) acetate (Scheme... 

In terms of recent patent activity related to Protox inhibitors, a series of N-substituted phenyl isothiazolone Protox herbicides were prepared to investigate the potential of the isothiazolone heterocycle ring to act as a bioisostere for comparable tetrahydrophthalimides such as compound 80 [93] (Fig. 3.21). The 2-(4-chloro-3-isopropoxycarbonyl)phenyl isothiazole-1,1-dioxide 83 was the most active... 

Without additional reagents 3-Isothiazolone from cephem ly -oxide ring... 

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