Methylene-3-thietanone

Treatment of 2,2,4,4-tetramethyl-3-thietanone with diiron nonacarbonyl gives the binuclear iron complex 381. 2,2-Dimethyl-3-thietanone undergoes oxidative dimerization to 382 on treatment with potassium ferricyanide. Methylene-3-thietanones such as 359 add chlorine from thionyl chloride to the carbon-carbon double bond. 2,2,4,4-tetramethyl-3-thietanone is converted to the 3-thione in 14% yield by treatment with hydrogen sulfide-hydrogen chloride. Electrochemical reduction of the thione produces radical anions. 

The presence of several 2-methylene-3-thietanones and 2-methylene-3-hydroxy-thietanes in African plants of the tribe Arctotideae (e.g., 356) has been estab-... 

The unstable bis-3-methylenethietane 392 is obtained by desulfurization of the thiirane 391 that is derived from 384, The thermal rearrangement of a-diazoketone 362 gives the 2-methylene-3-thietanone 363 in quantitative yield. 

Irradiation of 393 at 253.7 nm effects a reverse cycloadditionThe photochemical decomposition of the 2-methylene-3-thietanone 363 to 375-377 has been discussed previously (Section XV.4.D.). 4-Methylene-2-thietanthiones (e.g., 335) rearrange to either the 1,3-dithione or 338 in aprotic or protic solvents, respectively (Section... 

Thermolysis of the lithium salt of the tosylhydrazone of 2-isopropylidene-4,4-dimethyl-3-thietanone gives 2,3-bis(isopropylidene)thiirane. Treatment of 2-methylene-3-thietanones with thionyl chloride effects addition of chlorine across the carbon-carbon double bond. Radical ions of 4-methylene-2-thietanethiones have been obtained by electrolysis and examined by electron-spin resonance ... 

The intramolecular cyclization of ketones by thionyl chloride to methylene-thietanones has been discussed previously (Section XVI.3.A.). 

Thietanones also have been obtained by treatment of aliphatic ketones with an a-methylene group with thionyl chloride, usually in the presence of a base as shown for the synthesis of 359. A 3-thietanone was suggested as a possible structure for the product obtained by the acid-catalyzed hydrolysis of the bis-thioglycolic thioacetal of substituted benzaldehydes, but an elemental analysis was the only evidence. Treatment of l-diazo-3-phenylthio-2-propanone with acid gives the -phenyl salt of 3-thietanone (Section VII.1.). Similar 5-alkyl salts may be intermediates, but they readily decompose either by loss of the 5-alkyl group or... 

Aldol condensations at one or both a-methylene groups of 3-thietanone have been accomplished with formaldehyde, aromatic aldehydes (e-g-, the formation of 359), acetylenic aldehydes, and acetone. ... 

Methylene derivatives of thietanes have been obtained by the Wittig reaction of 3-thietanones, as in the preparation of 365 and the phosphonium ylide 345 with p-nitrobenzaldehyde (to give 354). A Wittig reaction also has been applied to a 2-thietanone. ... 

The a-methylene protons of 3-thietanone 1,1-dioxide are acidic (effervescence is observed in sodium bicarbonate solution). The base-catalyzed reaction of... 

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