Thietanes ring synthesis from

A number of papers describe the synthesis of thietane rings starting from thiirane rings. Lucchini et al. studied the different reactivities of cis and trans di-fert-butylthiiranium ions, 96a and 96b, with water <1997JOC7018>. It was demonstrated that the reaction of cis di-fert-butylthiiranium ion 96a with water led first to the formation of an open-chain alcohol 97, which, after ring closure, formed the trans di-/r y-butylthiiranium ion 96b. The trans Ai-tert-butylthiiranium ion 96b then rearranged to the thietanium ion 98 (Equation 31). 

Mildly basic to neutral conditions for the ring closure of 1,3-halohydrins include tetra-phenylantimony methoxide as an effective non-basic reagent for oxetane synthesis from 1,3-bromohydrins (90S106). The salts of (3-halo acids cyclize in ionizing media to oxetan-2-ones, as do (3-diazonium carboxylates (64HC(l9-2)787). Thietanes are obtained analogously. 

This chapter continues this work covering the literature of the last 10 years, that is, from 1996 until 2005. The preparation of this review was based on a literature search through SCOPUS and the Beilstein Database, which revealed 104 important papers published within this period. This chapter is organized in accordance with the general structure of CHEC-III, which includes a division into 12 sections including the same aspects as in CHEC-II(1996). For some aspects of thietane and thiete chemistry, such as their synthesis from six- and seven-membered rings, no new papers were published within the discussed period. 

Among the available methods to synthesize fused-ring thietes and bi- or tricyclic thietanes (but not spiro-com-pounds), the most efficient method seems to be the synthesis from acyclic precursors with the same number of carbons. Photocyclization reactions lead to thietes and thietanes in satisfactory to high yields. Mono- and disaccharides bearing fused thietane moieties have been synthesized using this method. 

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. ... 

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