Methylene thietanes oxidation

The same equatorial preference is also manifested in the 3,3-disubstituted thietane oxides . Thus, the NMR spectra of 5e,f contain two Me singlets at 1.23 and 1.30 ppm and two methylene multiplets at 3.03 and 3.53 ppm (in CDClj). The large difference in the chemical shifts of the axial and equatorial a-methylene hydrogens is characteristic of an axial nonbonded electron pair on sulfur (conformation 5e equation 73). This conformational preference is corroborated by the small differences in the chemical shifts of the two methyl groups, and fits the contention that 1,3-diaxial interactions are responsible for this ultimate result. Certainly, these interactions are greater in the conformer 5f. 

Flash vacuum pyrolysis (FVP) represents a special method for inducing decomposition of thietane compounds. Block et al. succeeded for the first time in the preparation of methylene sulfine in the gas phase, applying this method to thietane 1-oxide. The reaction starting at 600°C was followed by mass and microwave spectroscopy. 

The mechanism of thietan-3-one formation by oxidation of 4-arylbutan-2-ones with thionyl chloride involves oxidation exclusively at the a-methylene... 

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