Methylene-1,3-dithietanes

The 4-methylene-l,3-dithietane-2-ones lose carbon oxysulfide to give thio-ketenes that dimerize to 2,4-dimethylene-l,3-dithietanes, as exemplified by the flash-vacuum thermolysis of 551. Reaction of several methylene 1,3-dithietane-2-ones with secondary amines also appears to proceed via loss of carbon oxysulfide followed by addition of the amine to the thioketene. An exception to the loss of carbon oxysulfide is the reaction of a guanidine derivative with 551 to give the ring-opened product 552. ... 

The two most common methods of synthesis of methylene-1,3-dithietanes are the reaction of 1,1-dihalides or their equivalents with salts of 1,1-dimercapto-... 

Acetyl groups in desaurins may be oxidized to carboxylic acid groups by sodium hypochlorite without affecting the basic bis(methylene)dithietane structure. Treatment of 575 with bromine in chloroform effects replacement of the two methine hydrogen atoms by bromine atoms.An unusual methylene-1,3-dithietane reacts with bis(trifluoromethyl)thioketene to give a complex structure embodying a new methylene-l,3-dithietane and a 2-methylenethietane. Bis-... 

Reaction of 2-methylene-1,3-dithietanes (256) with hydrazines affords 5-thiolpyrazoles (257) <90JHC567>. These last products were converted into 5-S-methyl pyrazoles (258) by methyliodide. Other authors <87JCS(P1)1945> have used a-aroyl-a-bromoketenedithioacetals to prepare 3(5),4-bis(alkylthio)pyrazoles. 

Phosgene acts as an acylating agent to give methylene-substituted l,3-dithietan-2-ones (66AG(E)970, 79LA1715). 

The reaction of 1,3-dithietane 92f substituted with a diethylphosphoryl group with G-nucleophiles is analogous to the previously reported reaction. Its condensation with different C-nucleophiles, such as cyclic and acyclic a-carbonyl-methylenes and a-carbonylhydrazones, gave a number of [2,l-3]fused phosphono-substituted thioxopyranes 97, 100, 103, 107, oxadiazine 109, and thiazine 105 (Scheme 12), which are of potential biological interest <2002PS1885>. 

A similar reaction of the methylene derivatives 194 with carbon disulfide under (PTC) conditions followed by the action of 4,4-dibromo-l-phenylpyrazolidine-3,5-dione 195 produced the spiro-1,3-dithietanes 196 (Scheme 24 Table 10) <2000PS159>. 

Tetrachloro-l, 3-dithietane forms a bis adduct with mercury (I) nitrate,whose structure was investigated by IR and Raman spectra. A cyclo-pentadienyl manganese(0) dicarbonyl complex of the dimer of 2,3-diphenylcyclo propenethione has been reported. Raney nickel desulfurizes the tetraester 538 and the desulfurization of the questionable dithietanes obtained by dimerization of thiofluorenone and thiobenzophenone give, respectively, bis-fluorenylidene and tetraphenylethylene. The electrochemical oxidation of 1,3-dithietane has been investigated. 2,2 -[Oxybis(methylene)]bis-l,3-dithietane is inert to boron trifluoride etherate after 30 days at room temperature. ... 

Dimerization of sulfene yields disulfone 546, whose protons are readily replaced by deuterium, bromine, or trimethylsilyl groups. Sulfone 546 reacts with 2,6-dimethyl-4-pyrone to give an exo-methylene derivative and it may be tetra-methylated. Other disulfones are obtained by oxidation of 1,3-dithietanes with potassium permanganate or chromium trioxide-fuming nitric acid for resistant dithietanes. As mentioned above, peracetic acid oxidizes a disulfoxide, mono-sulfone, or a monosulfone-monosulfoxide to the disulfone 546. 57b,iii3a 2,2,4,4-Tetra(trifluoromethyl)-l,3-dithietane 537 is oxidized only to the monosulfone 547, even with chromium trioxide-hot, fuming nitric acid the disulfone is only... 

In the reactions of 1,1-dihalides, tin salts of 1,1-dimercaptoalkenes give somewhat better yields (only an 18% yield of 564 is obtained with the disodium salt). The reaction of active methylene compounds with carbon disulfide is a common method for obtaining 1,1-dimercaptoalkene derivatives, as exemplified in the synthesis of 565. The reaction of dimercaptoalkene salts with phosgene yields 2-keto-4-methylene-l,3-dithietanes. 

The formation of desaurins from ketones, carbon disulfide, and base 1275,1281,1282,1285-1290 believed to involve nucleophilic attack on a thioketene by the dianion of a 1,1-dimercaptoalkene, as shown for the synthesis of 572. Related syntheses involve the use of thiophosgene instead of carbon disulfide and the use of diazoalkanes or phosphonium and sulfonium ylides instead of a ketone and base. Treatment of perfluoroiso-butylene with fluoride ion and elemental sulfur in a dipolar, aprotic solvent ° °° or with sources of anionic sulfur (potassium sulfide, sodium hydrosulfide,potassium thiocyanate,sodium thiosulfate, dithiocarbamate salts, dithiophosphate salts ) give the dimer (573) of bis(trifIuoromethyl)-thioketene. Similarly, other 2,4-bis(methylene)-l,4-dithietanes are obtained by treating 2,2-dichlorovinyl ketones with anionic sulfur re-... 

Salts of 1,1-dimercaptoalkenes can be dimerized to 2,4-bis(methylene)-l,3-dithietanes with the formal loss of hydrogen sulfide by treatment with electrophilic... 

Novel base-catalyzed rearrangements of certain 3-hydroxy-5-alkylthio-l,2-thiazoles, for example, 576, to methylene-l,3-dithietanes have been reported. 1236,1237 aldol condensation of 2,6-dime thy 1-4-py rone with 1,3-dithietane 1,1,3,3-tetroxide gives a low (2%) yield of a 2-methylene-l,3-dithietane 1,1,3,3-tetroxide. ... 

The most common reaction of 2,4-bis-(methylene)-l,3-dithietanes with nucleophiles involves an apparent Michael addition to an electron-deficient double bond followed by ring-opening. Further reactions may ensue depending on the functional groups present. The reactions of 578 have been extensively investigated. Reactions have been reported with ethoxide ion and thiolate ions, ammonia and amines " " - (e.g., the formation of 579), hydra-... 

Abequito AC 84633 AI3-29106 Benzenamine, 4-chloro-N-1,3-dithietan-2-ylidene-2-methyl- Benzene-amine, 4-chloro-N-1,3-dithietan-2-ylidene-2-methyl- (4-Chloro-2-tolyl)-dithio-imidocarbonic acid cyclic methyl-ene ester CL 84,633 Cyclic methylene (4-chloro-o-tolyl)-dithioimidocarbonate ENT 29106 Nimidane Nimidano Nimidanum. Acaricide. Crystals mpn43-46°. Am. Cyanamid. 

Alkylation of appropriate dithiolate anions with methylene bromide is a useful route to dithietan derivatives, (122) being formed in this way from (118 = Ph, R = H), whilst potassium diethoxyphosphinyldithio-... 

Active-methylene compounds are converted into the corresponding thioketones by successive reaction with thionyl chloride and triphenylphosphine. The thioketones thus prepared are too unstable to be isolated, and they undergo dimerization to give the 1,3-dithietans (57)—(59). However, the intermediacy of thioketones has been confirmed by u.v. spectrometry. The transient formation of thioketone and then its dimerization or a Diels-Alder reaction with an olefin has... 

---