Thietanone 1-oxides

Tetramethyl-3-thietanone 1-oxide 400 is obtained in 69% yield by oxidation of the thietane with peracetic acid in benzene. Amides of 3-thietanone-2,4-dicarboxylic acid 1-oxide are said to be obtained by treatment of amides of acetone dicarboxylic acid with thionyl chloride and 3-thietanone-l-oxides may be intermediate in the reaction of ketones with thionyl chloride. The -oxide of 3,3,4,4-tetraphenyl-2-thietanone may be an intermediate in the oxidation of the thietanone by nz-chloroperbenzoic acid, which is discussed in Section XIII.4.E. ... 

In contrast, the corresponding sulfoxides do undergo such a bond rupture between the allylic C-atom and the neighboring S-atom as a first chemical step after photoexcitation.As shown in Scheme 15, 2H,6H-thiin-3-one-l-oxides 47 photoisomerize to 3H,7H-l,2-oxathiepin-4-ones 48, which undergo a further thermal ring contraction to thietanone-1-oxides 49 via a 2,3-sigmatropic rearrangement. 

An interesting reaction related to the ring expansions of penicillin S-oxides (208) was observed in the thermal rearrangement of 2,2,4A-tetramethyl-thiethan-3-one 1-oxide to the five-membered thiolane ring 209. Oxidation attempts of these thermally unstable thietanone oxides led via ring opening to the more stable heterocycle. The reaction mechanism (Scheme 11) was... 

Syntheses of thiiranoradialenes from a 3-thietanone derivative. Transformation of 2-methylthiacyclobutane in the presence of aluminum oxide. ... 

Oxygen can be introduced into the a-positions of thietanes by treatment of the thietane with lead tetraacetate as in the formation of (204) (75JOC3046). Thietanones can be prepared by hydrolysis of thiete enamines such as (205) (65LA(684)103) or by oxidation of 3-thietanol with DMSO/benzoic anhydride (78PS(4)167>. Thietanones can be converted into various ring-substituted sulfur derivatives as already illustrated in reactions of (68) and preparation of (199). 

This method is not very useful because of the ease of oxidation of the sulfur atom. Among the first preparations (18-20% yield) of 3-thietanone, itself, was the Oppenauer oxidation of 3-hydroxythietane with benzil. A 72% yield of... 

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. 

Thietanone 1,1-dioxides are unknown, although the tetraphenyl compound may be an intermediate in the oxidation of the 2-thietanone 308 with m-chloro-perbenzoic acid to the sulfinic-carboxylic acid anhydride 331. The methods discussed below apply to 3-thietanone 1,1-dioxides and derivatives. 

Tetramethyl-3-thietanone is oxidized in 97% yield to the sulfone by peracetic acid. ... 

This weakening of the bond between the allylic carbon and the neighboring atom can lead to bond rupture as illustrated in the photoisomerization of 2H,6//-thiin-3-one-l-oxides to 3//,7H-l,2-Oxathiepin-4-ones [14], These seven-membered ring systems undergo further thermal ring contraction to thietanones via a 2,3-sigmatropic rearrangement followed by a Pummerer reaction (Scheme 10). 

Oxidation of simple thietans with peroxy-acids gives monoxides and dioxides.However, oxidation of tetraphenyl-2-thietanone (89) with m-chloroperoxybenzoic acid gives (90), which is a stable carboxylic-sulphinic acid anhydride. Thietan dioxides are formed in the oxidation of thietans by NaMn04. 2-Arylsulphonyl-3-aryl-oxaziridines oxidize sulphides (including thietans) to sulphoxides. 3-Hydroxythietan can be oxidized to 3-thietanone, without oxidation at sulphur, with DMSO and benzoic anhydride. ... 

---