Facile syntheses of allylic allenethiosulfinates and -sulfonates, and of β-iodo α,β-unsaturated γ-sultines

The regiospecificity of the 1,4-addition of the recently reported novel alkoxy chlorodisulfides to 2-methyl-1,3-butadiene has been established. Allyl allenethiosulfinates formed by spontaneous [2,3]-sigmatropic rearrangement of the addition products were oxidized at 4 °C to the corresponding thiosulfonates. Periodate oxidation at room temperature, preferably in the presence of I₂, resulted in oxidative cleavage and cyclization to β-iodo α,β-unsaturated γ-sultines. Such sultines, with varying degrees of γ-alkyl substitution, were also conveniently prepared by reaction of iodine with alkyl allenesulfinates.