210626-06-5Relevant articles and documents
Versatile route to functionalized 1H-2-benzothiopyrans and 1H-2- naphthothiopyrans by electrophilic cyclization of Bis(arylmethylthio)acetylenes: 2-Benzo- and 2-naphthothiopyrylium salts
Klein,Bergemann,Yehia,Fanghanel
, p. 4626 - 4631 (2007/10/03)
Substituted 1H-2-benzothiopyrans find applications as pharmaceutically active compounds or synthons for more complex sulfur heterocycles. However, restricted variability in their synthesis limits the application for research or industrial purposes. To develop a direct and fast route to substituted and functionalized 1H-2-benzothiopyrans, we investigated the ring closure of symmetrical bis(arylmethylthio)acetylenes with iodine monochloride or bromine. This facile reaction yielded 1H-3-halo-4-arylmethylthio-2-benzo- and 2-naphthothiopyrans via postulated vinyl cations in yields of 47-86%. Substituted 2-benzo- and 2-naphthothiopyrylium salts were prepared by hydride abstraction with triphenylcarbenium tetrafluoroborate from the products, further enhancing the synthetic potential of the found cyclization reaction.