Reaction of thiolsulfinates with trihaloacetic anhydrides. II : Addition of sulfenyl trihaloacetates to olefins

Treatment of thiolsulfinates with trifluoro- or trichloroacetic anhydride at -20°C in the presence of various olefins in carbon tetrachloride afforded the corresponding β-trifluoro- or trichloroacetoxy sulfides in good yields. The β-trihaloacetoxy sulfides are considered to be resulted by the electrophilic addition of the sulfenyl trihaloacetates, formed as transient intermediates, to olefins. The addition takes place stereospecifically in $\text{trans}$ manner and the regioselectivity for the addition with unsymmetrical olefins obeyed the Markownikoff orientation rule, except 3,3-dimethyl-1-butene which gave initially the anti-Markownikoff product $\text{3}$ due to the steric hindrance, however the adduct $\text{3}$ is readily converted to the Markownikoff product $\text{22}$ upon heating. Since the addition is highly regioselective and stereospecific, this is a very convenient procedure for the syntheses of β-trihalo-acetoxy sulfides.