title: Lewis acid catalyzed cascade reactions of 1,6-diynes and 1,6-enynes with vinylidenecyclopropanes.
abstract: Lewis acid catalyzed reactions of N-(4-hydroxy-4,4-diarylbut-2-ynyl)-4-methyl-N-prop-2-ynylbenzenesulfonamides or 1,1-diphenyl-4-prop-2-ynyloxybut-2-yn-1-ol (1,6-diynes) 1 and N-allyl-N-(4-hydroxy-4,4-diarylbut-2-ynyl)-4-methylbenzenesulfonamides (1,6-enynes) 2 with vinylidenecyclopropanes 3 selectively produce polycyclic compounds 4, 5 and 10 as well as isopropylidene-3,3-diarylcyclobut-1-enylmethyl derivatives 6 or 7 in good to high yields depending on the substituents on the benzene ring of 3 under mild conditions. An interesting PtCl(2)-catalyzed cyclization of 6 and a Cu(OAc)(2)H(2)O catalyzed Eglinton coupling reaction of 5 and 10 to produce the corresponding 5-isopropylidene-6-methyl-1-(toluene-4-sulfonyl)-7-vinyl-1,2,3,4,5,8-hexahydroazocine derivatives 8 and the coupling products 9 and 11 in good yields have been disclosed, respectively. Plausible mechanisms of these processes have been proposed that belong to a cascade rearrangement followed by the Friedel-Crafts reaction, an intramolecular proton transferring and a cyclization reaction.
authors.affiliation: State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai, 200032, China.
authors.forename: Liang-Feng
authors.initials: LF
authors.lastname: Yao
authors.forename: Min
authors.initials: M
authors.lastname: Shi