Novel cyclization of diallenic sulfones

Exploration of Braverman Reaction Chemistry. Synthesis of Tricyclic Dihydrothiophene Dioxide Derivatives from Bispropargyl Sulfones

“…The spontaneous thermal cyclization of bisallenyl sulfones to furnish thiophene dioxide derivatives was first reported by Braverman in 1974 1. Subsequent studies revealed that this transformation likely proceeds through a diyl intermediate, 4 → 5 → 6 → 7 → 8 (Scheme 1), followed by several tautomerizations rather than an intramolecular Diels-Alder reaction of either a bis(3-aryl)allenyl sulfone (i.e., 4 → 6 directly) or a related allenyl, propargyl sulfone 2-4.…”

“…The reported yield for this latter process approached quantitative, although there was no report of a yield or description of an experimental procedure for the 1 → 8 reaction 3. The formation of a thiophene dioxide such as 7 , whether transiently or as an isolable intermediate,1,4 raised the possibility of linking the Braverman chemistry with the rich Diels-Alder chemistry of thiophene dioxides5-8 in a multi-step transformation that could forge several new rings from simple precursors. Thus, tethering a dienophile trap to a nascent thiophene dioxide emerging from the Braverman chemistry might test the hypothesis that intramolecular Diels-Alder cycloaddition might compete with proton transfer within an intermediate like 7 and ultimately deliver a pentacyclic product.…”

Base-Catalyzed Reactivity of Sulfur- and Selenium-Bridged Cyclic Alkynes: Tandem Isomerization and Cycloaromatization versus Isomerization and Nucleophilic Addition

“…This was in turn based on the thermal cyclization of diallenyl sulfones, a reaction discovered by us some three decades ago and demonstrated to involve a diradical intermediate. [6] However, subsequent mechanistic studies by Nicolaou [7] and others [8Ϫ12] resulted in the conclusion that their biological activity was due to an alternative mechanism, the Maxam-Gilbert [13] mechanism, involving nucleophilic addition of DNA to the diallenyl sulfones. In fact, this conclusion is hardly surprising in view of the relatively high temperature required for the diallenyl sulfone cyclization.…”

“…In fact, this conclusion is hardly surprising in view of the relatively high temperature required for the diallenyl sulfone cyclization. [6] It is well documented that introduction of various functional groups such as crown ethers or β-dicarbonyl moieties into intercalating molecules, which can form cationic complexes with metal ions, may increase the overall binding properties of these molecules to DNA, which is an anionic the nature of the base. Because of the lack of stability of the expected diradical intermediate, the corresponding allenic sulfones undergo nucleophilic addition, which is responsible for their DNA-cleaving properties.…”

Reaction of bis(prop-2-yn-1-yl) sulfide with sulfur dichloride. First example of cyclization of bis(prop-2-yn-1-yl) chalcogenides by the action of chalcogen halides

“…Electrophilic reactions of sulfur dichloride with various allyl and diallyl systems were reported [1][2][3][4][5][6]; however, among propargyl derivatives, data on reactions of sulfur dichloride only with propargyl alcohols are available [7][8][9]. These reactions lead to the formation of diallenic sulfones rather than addition products.…”