Ethynyl p-tolyl sulfone (Tosylacetylene) may be used in the synthesis of 2-(4-methylphenylsulfonyl)ethenyl (tosvinyl, Tsv) protected derivatives. It may be used as starting reagent for the synthesis of optically active indan-2-ols.
Ethynyl p-Tolyl Sulfone is a dienophile used in electrocyclic reactions such as dipolar cycloaddition, Diels-Alder reaction, and ene
cyclization; electron-poor Michael acceptor in conjugate additions; undergoes direct displacement with
organometallic complexes to give aryl- or alkylacetylenes.
Ethynyl p-Tolyl Sulfone has been prepared by several groups over the years employing a variety of synthetic
strategies including ethynyl Grignard addition to p-toluenesulfonyl fluoride, dehydroiodination of (E)-2-iodo-1-
tosyl-1-ethene, oxidative elimination of β-[(4-methylphenyl)seleno]vinyl sulfone, dehydrobromination of cis-and trans-2-bromovinyl 4-methylphenyl sulfone,23 diazotization of 4-[(4-methylphenyl)sulfonyl]-5-
aminoisoxazole, and oxidation of ethynyl thioether. The modified strategy commonly used today is an
established Friedel-Crafts based procedure first performed by Bhattacharya et al. but recently exploited by
Waykole and Paquette (eq 1). Its simplicity and mildness has shown it to be broadly useful since it bypasses
the need for immoderate conditions encountered in the earlier strategies.
Decomposition of the intermediate complex p-toluenesulfonyl chloride-aluminum chloride-bis(trimethylsilyl)acetylene with hydrochloric acid and ice is exothermic and due caution is
recommended. Also, a nitrogen atmosphere is suggested throughout its preparation due to the hygroscopic nature
of the reagents and intermediate(s) involved.
Recrystallise the sulfone from pet ether, *C6H6 or EtOH (m 66o), and dry it in a vacuum. [Beilstein 6 III 1397, 6 IV 2160.]
