The reaction of beta-iodo-alpha,beta-unsaturated gamma-sultones (i.e., 4-halo-1,2-oxathiole 2,2-dioxides) in aprotic polar solvents such as DMSO or acetone, with 'soft' nucleophiles such as iodide or thioacetate, yields an allenesulfonate by a very facile halophilic ring-opening E(2)-elimination. The 'harder' nucleophile, azide ion, reacts under the same conditions to yield the corresponding beta-azido-alpha,beta-unsaturated gamma-sultone (i.e., 4-azido-1,2-oxathiole 2,2-dioxide), displacing the beta-halide by an addition-elimination mechanism. In contrast, in the hydroxylic solvent CD(3)OD at ambient temperature, various nucleophiles yield neither of the above-mentioned products, but catalyze a rapid replacement of the Calpha-H by deuterium. Factors underlying this intriguing rapid exchange are proposed. Interestingly, the beta-bromo analogue exhibits similar reactivity except for the halophilic ring-opening. Calculations indicate the relative importance of the beta-halogen and the S-O(-C) bonds in enhancing the acidity of the H-C(alpha)S(O)2- grouping.

Regio-and stereospecific electrophilic addition reactions of selenium tetrachloride and selenium tetrabromide to propargyl alcohols are reported. (Z,Z)-Bis(b-chlorovinyl)selenium dichlorides were isolated in high yields, and their reactivity was dependent on their substitution pattern. Products derived from unsubstituted, a-methyl-, or a,a-dimethylpropargyl alcohols readily underwent transfer of chlorine atoms to one of the two double bonds. (Z,Z)-Bis(b-chlorovinyl)selenium dichlorides derived from g-phenyl-or g-isopropenylpropargyl alcohols underwent cyclization to form benzoselenophene derivatives; this was accompanied by the formation of the corresponding dichloro-substituted allylic alcohols. In contrast, selenium tetrachloride reacts with g-phenylpropargyl alcohol exclusively as a chlorinating agent, giving (3-chloroprop-1-yn-1-yl)benzene quantitatively. Products of regio-and stereospecific electrophilic addition of selenium tetrabromide are also described. Reaction mechanisms are proposed.

Oxathiole derivatives R 0250β-Halo-α,β-unsaturated γ-Sultones. -Treatment with hard nucleophiles in DMSO results in formation of the expected substitution products such as (III). In CD 3 OD, however, unusual H-D exchange takes place giving α-deuterated sultones like (II) (yields not given). Reaction of β-iodo sultones with soft nucleophiles such as KSAc and NaI provides allenesulfonates. -(BRAVERMAN*, S.; PECHENICK-AZIZI, T.; MAJOR, D. T.; SPRECHER, M.; J. Org. Chem. 72 (2007) 18, 6824-6831; Dep. Chem., Bar-Ilan Univ., Ramat Gan 52900, Israel; Eng.) -Jannicke 02-123

Thirty-five substituted bis(propargyloxy) disulfides were successfully prepared in good to excellent yields, and their reactivity was found to be strongly dependent on the substitution pattern of the reactant. Inter alia they undergo surprising tandem sigmatropic rearrangements and cycloadditions. Three heretofore unknown product types were isolated and fully characterized: 6,7-dithiabicyclo[3.1.1]heptan-2-one 6-oxide derivatives, two isomeric 1,2-dithiete 1,1-dioxides (a,b-unsaturated four-membered cyclic thiosulfonates) from bis(propargyloxy) disulfides with a-or galkyl-substituted propargyl groups, and two isomeric 2-oxa-5,7-dithiabicyclo[2.2.1]heptane 5-oxides from bis(propargyloxy) disulfides with a-tert-butyl-or a,a-dialkyl-substituted propargyl groups.

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