1.3- Diketones sulfenylation

TL 24 2009 (1983) (0-keto ester) 25 1241 (fi-diketones to /J-hydroxy ketones), 4623 (3-oxo glutarate and adipate esters), 5083 (a-sulfenyl-/J-keto esters) (1984) 26 101 (/J-keto esters), 771 (a-PhS ketone), 4213 (/J-keto esters) (1985) 27 565 (/J-diketones to /J-hydroxy ketones), 1915 (a-keto esters) 2091 (/J-keto esters), 2657 (/J-keto esters), 3547 (2-acyl- 1,3-dithianes 2-acylthiazoles), 4737 (a-chloro ketones), 4817 (a-PhSOj ketone), 5275 (/J-keto esters and amides), 5281 (/ -keto esters), 5397 (a-chloro ketone, /J-keto ester), 5405 (/J-keto thio- and dithioesters) (1986) 28 2709 (/ -chloro-a-keto ester), 3189 (/J-keto ester) (1987) 29 4769 (3- and 4-nitro ketones), 4865 (/J-keto ester), 6167 (5-acetyl-2-isoxazolines) (1988) 30 2707 (yS-keto ester), 3701, 5705 (/J-keto ester) (1989) 31 1159 (/J-keto ester), 1615 (/J-keto ester), 1811, 3631 (/J-keto esters), 4025 (a-hydroxy ketone), 4195 (2-acyl-2-alkenoate ester), 5575 (y- and 5-keto sulfones), 7463 (/J-diketone to /f-hydroxy ketone)... 

The sulfenylation of metalloimines is equally applicable to ketones, although using more reactive sulfur electrophiles it is possible to bring about reaction on the unmetallated enamine. ° Sulfenylation of ketone enol silyl ethers also proceeds well with the more reactive sulfur species. Sulfenamides and their derivatives e.g. 11) are particularly suited to the direct sulfenylation of ketones and active methylene compounds such as -diketones, -keto esters and malonates, which undergo facile reaction at room temperature (equation 5). This procedure, however, does not appear to have been exploited for the dehydrogenation of active methylene compounds icf. Section 2.2.4.1). By preparing the dianion (13)... 

The a-sulfenyl group can be replaced by a benzothiazolthio group, as demonstrated in the synthesis of the 1,4-diketone (CXXXIV), a precursor of cw-jasmone [Eq. (65)] [10]. The geminal dicarboxylic acid (CXXXVI) can also be transformed into the 1,4-diketone (CXXXIV) by electrochemical decarboxylation as in Eq. (66) [6], suggesting that the substituted malonic acid group is synthetically equivalent to a carbonyl group. 

Diketones are also readily sulfenylated in the 2-position by benzenesulfenyl halides, and Shvedov et al. have reported the reductive cyclization of products such as 94 with zinc in acetic acid to benzothiazines... 

Diketones. a-Substituents of ketones such as a-sulfenyl derivatives are readily replaced by alkoxy groups in the presence of mercury(II) acetate. 1,2-Diketones are accessible therefrom. 

Diketones. The reagent is somewhat more reactive than diphenyl disulfide for sulfenylation of lithium enolates of ketones. The products can be converted into protected fojms of 1,2-diketones or into the products of cleavage. 

Chlorothioethers from ethylene derivs. and sulfenyl chlorides C = C C(C1)C(SR) s. 33, 531 addition of polyfluoro-rcrr-alkylsulfenyl chlorides s. A.Y. Sizov et al., Izv. Akad. Nauk SSSR Ser. Khim. 1988, 1186-9 addition of metal a-chlorosulfenyl-p-diketonates s. G.M. Svistunov et al., Zh. Obshch. Khim. 58, 1178-9 (1988). 

Alkylation of j8-diketones using polymers as supports for the intermediate enolate anion has also been reported (Gelbard and Colonna, 1977). Reaction of several cyclohexyl j3-diketones with Amberlite IRA-9(K) formed a resin-linked j8-diketonate that could be readily alkylated. Similarly, it was shown that alkylation of phenoxide anions can be readily effected when the anions are supported via an ionic bond with the resin (Gelbard and Colonna, 1977). Alkylations of /3-diketones were also shown to occur if a fluoride-substituted, strongly basic resin (Amberlyst A26, A27, or Dowex MSA-1) is used (Miller et at., 1978). In this case, the presence of the fluoride ion was necessary before reaction would proceed. Considering the report on the use of Amberlite IRA-900— a very similar resin— the necessity for a fluoride ion is puzzling. In the same publication, the 0-alkylation of phenols, the sulfenylation of /3-diketones, and the Michael addition of a thiol to an ot,/8-unsaturated ketone were also investigated. 

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