1.2- Oxathiete derivatives

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... 

Oxathietanes and oxathietes have been cited in the literature only as reactive transient intermediates and not as isolated relatively stable products. The cycloaddition of dimethyl sulfoxide to the acetylene derivative 277 yielded via the 1,2-oxathiete 278 the acyclic structure 279 ° (Eq. 76). 

Over the last decade there has been very few theoretical studies conducted on 1,2- and 1,3-oxathietanes and associated derivatives. In fact, there are no new reports for 1,2-oxathietanes, /3-sultines, and 1,2-oxathietes. Several reports for /3-sultones, a 1,3-oxathietane, and a sulfurane are in existence. The reader should consult the previous version of this chapter <1996GHEC-II(1B)1083> for previous theoretical treatments (mainly low level calculations) of 1,2-oxathietanes, 1,3-oxathietanes, and several 1,2-oxathietes. 

The previous chapter in CHEC-II(1996) reported on the stability and derived thermochemical data for the isomerization of /3-sultones, the cycloreversion of 1,2-oxathietanes, the relative stability of 1,2- and 1,3-oxathietanes, the isomerization of 1,2-oxathietes, as well as aspects related to stereoisomerization <1996CHEC-II(1B)1083>. Unfortunately, no new studies or information has been presented over the last decade. The only experimental observation worthy of mention is that an equilibrium mixture of the thioketone 27 along with the 6-oxa-7-thiabicy-clo[3.1.1]heptane 28 was isolated in 48% yield from the thermal decomposition of a precursor dithiirane oxide <1997BCJ509>. This indicated that the activation barrier for cycloaddition-cycloreversion is low at ambient temperature. 

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