1.2- Oxathietane 2-oxides

Preparation of stable -sultines. Crystal structure of 2,2-bis(p-fluo-rophenyl)-3,3-dimethyl-1,2-oxathietan 2-oxide. ... 

The thermal decomposition of 1,2-oxathietane 2-oxides invariably leads to loss of sulfur dioxide and accompanying alkene formation (Scheme 17) (73JA3420, 78BAU142). The lack of any solvent polarity effect on rate (75CC724) as well as supporting theoretical calculations favor a concerted loss of sulfur dioxide without requiring a strained [[Pg.459]

The intermediacy of a 4-imino- 1,2-oxathietane 2-oxide from the addition of sulfur dioxide to ketenimines was inferred from the trapping with methanol. The final isolated product in absence of methanol, l,2-thiazetidin-3-one 1-oxide, was established by X-ray (Scheme 42) (81CC350). 

Several examples of polyhalogenated alkene addition to sulfur dioxide (60JA6181, 66JCS(C)ll7i> are known to give moderately stable 1,2-oxathietane 2-oxide adducts (Scheme 99) (78BAU142, 79BAU106). 

XXX. 1,2-OXATHIETANES 1,2-OXATHIETANE 2-OXIDES (jS-SULTINES) 1,2-OXATHIETANE 2,2-DIOXIDES (j3-SULTONES)... 

A theoretical treatment of 1,2-oxathietane indicates planarity with aS-0 bond length of 1.669 A and a C-S-0 angle of 100.6°. The electronic spectrum was calculated. The character of the HOMO is largely that of the sulfur 3p orbital. A CNDO molecular orbital study of the retrocycloaddition of 1,2-oxathietane 2-oxide to sulfur dioxide and ethylene shows that strong heteroatom asymmetry lifts the stereoelectronic requirement that the thermal fragmentation occur by a suprafacial-antarafacial path. ... 

The 1,2-oxathietane 2-oxide 492 has a puckered ring (dihedral angle 159.7°), as is shown by x-ray analysis. The sulfoxide oxygen atom is axial. The geometry of 3,3,4,4-tetrafluoro-l,2-oxathietane 2,2-dioxide has been discussed. ... 

The S-0 stretching frequency in the IR spectra of 1,2-oxathietane 2-oxides is observed at 1150-1190cm . The carbonyl stretching frequency in 1,2-oxathietane-4-one 2-oxide is observed at 1840 and 1856 cm". The sulfonate IR absorptions in 1,2-oxathietane 2,2-dioxides are 1370-1408 and 1176-1235 cm", except for the fluorinated derivatives, the absorption of the tetrafluoro- 3-sultone being reported at 1470cm". Fluorine-19 (nmr) chemical shifts and coupling constants are useful in structural and conformational studies of... 

An intramolecular cyclization of -hydroxysulfoxides effected by At-chloro-succinimide, A bromosuccinimide, or sulfuryl chloride gives 1,2-oxathietane 2-oxides, for example, 496, via a sulfoxonium salt. These cyclic sulfoxonium intermediates have been suggested in the conversion of /3-hydroxy-sulfoxides to /3-chlorosulfones, and to a,j3-unsaturated sulfones, in the conversion of /3-ethoxycarbonylsulfoxides to alkenes and of /3-hydroxysulfides to /3-hydroxysulfoxides, and in the conversion of 3-hydroxy- 3-vinylsulfoxides (e.g., 497) to useful terpene building blocks. The yields of the products from 497 vary somewhat depending on the stereochemistry about the two chiral centers. The more highly substituted 1,2-oxathietane 2-oxides are the most stable, because of... 

Other retrocycloadditions may occur in the decomposition of /3-sultines, obtained by reaction of triplet sulfur dioxide with alkenes, to ketones and sulfines (or a carbene and sulfur monoxide) and in the decomposition of 1,2-oxathietane-4-one 2-oxides to carbon dioxide and a sulfine. The mass spectrum of 1,2-oxathietane 2-oxide shows a fragment attributed to sulfine. ... 

During the period under review these systems have been reported or postulated only as transient intermediates. The conversion of phenyl 2-hydroxyethyl sulphoxide into phenyl 2-chloroethyl sulphone on treatment with sulphuryl chloride proceeded via 2-phenyl-1,2-oxathietan 2-oxide as intermediate, and 1,2-oxathietan 2-oxides have been postulated as intermediates in the reactions of sulphur dioxide with olefins. 1,2-Oxathiet derivatives have also been proposed as reactive intermediates, and although the u.v. and i.r. properties of monothiobenzil are not consistent with its formulation as 3,4-diphenyl-l,2-oxathiet, its mass... 

Calculations concerning the stabilities of 1,2-oxathietan 2-oxide, 1,2-oxathietan-3-one and its enol, and 1,2,3- and 1,3,2-dioxathietans have appeared. 

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