Thiacyclophane Cages and Related Bi- and Tripodal Molecules via Transient Polysulfenic Acids

A series of bis- and tris-bridged thiacyclophane S-oxides, as racemates or <i>meso</i> products, have been synthesized with a new procedure. Starting from the corresponding thiols, in three steps, transient polyarene- and polyarylmethane-sulfenic acids were generated in the presence of di- and triethynylbenzenes. The thermal <i>syn</i>-addition of these sulfenic acids onto the triple bonds of the unsaturated acceptors was conducted in CH<sub>2</sub>Cl<sub>2</sub> at 40 °C. The concentration of sulfoxide precursors of sulfenic acid and the sulfoxide/acceptor molar ratio addressed the <i>syn</i>-addition toward open-chain benzene sulfoxides or thiacyclophane S-oxides. Complete stereochemical control was observed in some reactions between polysulfenic acids and ethynylbenzenes, where the <i>meso</i> dithiacyclophane S,S‘-dioxides were obtained exclusively, whereas 1:1 mixtures of <i>meso</i>/<i>rac</i> dithiacyclophanes S,S‘-dioxides were isolated as products of other reactions. In almost all the cases, the obtained compounds were separated by column chromatography. The structure assignment of the new heterophanes was done on the basis of their diagnostic NMR spectra and X-ray crystallographic analysis of some of them. Open-chain polysulfinyl and polysulfinylmethyl benzenes, obtained as <i>meso</i>/<i>rac</i> mixtures, were separated and the products were fully characterized. Both synthesized cages, including trithia[3<sub>3</sub>](1,3,5)cyclophane S,S‘,S‘ ‘-trioxides, and bi- and tripodal benzene sulfoxides, appear promising in the field of coordination and material chemistry.