Thietane oxides synthesis

The addition of sulfenic acids to olefins207 has been successfully applied in the synthesis of thietanoprostanoids, the thietane analogues of prostaglandin245. The general synthetic scheme is presented in equation 83207. The key step is the thermolysis of either erythro- or (7ireo-2-f-butylsulphinyl-3-vinyl-l-ol (209) to give the corresponding alkenesulfenic acids 210, which cyclize spontaneously to a mixture of stereoisomeric thietane oxides. 

Chiral thietane dioxides, synthesis of 449 Chiral thiete dioxides, synthesis of 449 Chlorine compounds, as oxidizing agents... 

The preparation and investigation of the thietane oxide system (5a) is largely associated with stereochemical and conformational studies . The investigation of the thietane dioxides (5b) is substantially related to the chemistry of sulfenes , the [2 -I- 2] cycloaddition of which with enamines is probably the method of choice for the synthesis of 5b . The study of the thiete dioxide system (6) evolved, at least in part, from the recognition that the unstable thiete system 183 can be uniquely stabilized when the sulfur in the system is transformed into the corresponding sulfone , and that the thiete dioxide system is very useful in cycloadditions and thermolytic reactions. The main interest in the dithietane oxides and dioxides (7) appears to lie in the synthetic challenge associated with their preparation, as well as in their unique structural features and chemical behavior under thermolytic conditions . ... 

Petrov, V.A. Abstracts of 15th European Symposium on Fluorine Chemistry, Prague, Czech Republic, July 15-20, 2007, p 161. (a) Petrov, V.A. Marshall, W.J. Reactions of Polyfiuorinated Thietanes. Selective Synthesis of Polyfluorinated Thietanes S-Oxides and 2-Substituted 5-fiuoro-4-(trifiuoromethyl)-2,3-dihydrothiophenes, J. Fluorine Chem. 2009, doi 10.1016/j.jfiuchem.2009.06.011. 

In contrast to the a-oxy- or a-amino-substituted allylic esters, not many examples for a-thio substituted substrates and their application in Claisen rearrangements are described so far (Scheme 5.2.63). Lythegoe et al. applied the Ireland-Claisen rearrangement to the synthesis of a-mercapto acids such as 199 starting from allylic esters 198 [116]. 199 was oxidized and further converted into a,j8-unsaturat-ed esters or subjected to an oxidative degradation. Jones et al. used the Ireland-Claisen rearrangement of 200 in their syntheses of thietan oxides [117]. 

Although sodium sulphide reacts readily with haloalkanes [2] and activated aryl halides (see Chapter 2) [e.g. 3-5] in the presence of a quaternary ammonium catalyst to form symmetrical thioethers (Table 4.1), a major side reaction results in the formation of disulphides owing to the oxidation of the intermediate thiols under the basic conditions. Consequently, little use has been made of this procedure for the synthesis of thioethers [3, 6], but the corresponding reaction of the a,(0-dihaloalkanes to yield cyclic thioethers has proved to be a valuable procedure for the synthesis of thietanes [7] (Table 4.2). The ring closure with the secondary dihaloalkanes is considerably more difficult to effect than is the reaction of the primary dihaloalkanes. 1,3-Dihydrobenzo[c]thiophene (89%) is produced in the reaction of 1,2-bis(bromomethyl)benzene with sodium sulphide (Scheme 4.1) [8]. The direct... 

Application of the enamine-sulfene cycloaddition allowed the synthesis of 78 and 79 from the corresponding a,/l-unsaturated amines and sulfenes. Similarly, using enamine 80, the crystalline morpholino thietane dioxides (81) were produced. Elimination via the N-oxide gave the corresponding thiete dioxide, whereas reduction by LiAlH4 yielded the thietane 82. 

In the present review the ring systems containing one heteroatom are considered first, except for P-lactams which are given a special section at the end. Interest in azetidines continues to be stimulated by the discovery of the potentially useful trinitro derivative. The requirements for the stereoselective synthesis of substituted oxetane are being explored and derivatives of aluminium are useful in the stereoselective routes to oxetanones. The preparation and subsequent pyrolysis of oxetanones is suggested as an alternative to the Wittig route to olefins. Stereoselective routes to thietanes and thietane 1 -oxides are mentioned. 

The Pummerer reaction of 3,3-dibenzoyloxyethyl-thietane 1-oxide 32a with thymine in the presence of trimethyl-silyl triflate (TMSOTf), triethylamine, and Znl2 in dichloromethane allowed the synthesis of the thietane-derived thymidine 33a in 70% yield <1996TL7569>. The treatment of thietane-1-oxide derivative 32b under similar conditions but in toluene resulted in the modified nucleoside 33b in 30% yield (Scheme 9) <1996TL7569>. 

Heating several thietanes with sulfur or selenium yields 1,2-dithiolanes and a 2-selenathiolane, for example, 107 from 19, respectively. The reaction of 108 with sulfur provides a synthesis of thioctic acid. ° A somewhat similar reaction involves heating thietane with aluminum oxide whereby 1,2-dithiolane and hydrogen sulfide are produced, but the dithiolane yield is very low. A photochemical ring-expansion of 99 has been described in Section 11.5.1. ° Treatment of thietane with hexafluoroacetone gives a six-membered cyclic sulfenate. ... 

The principal method of synthesis of thietane 1-oxides is by oxidation of thietanes, a reaction discussed in Section II.5.C. Reagents used for oxidation are hydrogen peroxide, hydrogen peroxide-acetic... 

The discovery by Stork and Borowitz and Opitz and Adolph that the addition of sulfenes (RCH=S02) to enamines gives good yields of 3-aminothietane-1,1-dioxides (e.g., 132) has been extensively exploited in the synthesis of a variety of thietane sulfone derivatives. Truce, Breiter, Abraham, and Norell at about the same time showed that sulfene can add to ketene acetals to give 3,3-dialkoxy substituted thietane 1,1-dioxides (e.g., 133). The sulfenes are generated by dehydrohalgenation of methanesulfonyl chlorides with triethylamine. [Attempts to add sulfines (e.g., PhCH=SO) to enamines to give thietane 1-oxides were not successful.1 Sulfene additions have been reviewed. ... 

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