The synthesis of bicyclic ortho-quinodimethanes from tricyclic sulfones

Article abstract of DOI:10.1016/S0040-4020(97)10066-7

The first synthesis of bicyclic ortho-quinodimethanes from tricyclic sulfone precursors has been achieved. The required sulfones, 3,4,5,6- tetrahydro-1H-cyclohex[cd]benzothiophene-2,2-dioxide and 1,3,4,5,6,7- hexahydrocyclohept[cd]benzothiophene-2,2-dioxide, were prepared from α- tetralone and benzosuberone utilizing a ring closure proceeding through a sulfonium salt intermediate. The same strategy failed when frying to prepare the tricyclic sulfone of the indane series. Other contrasting reactivity was also noticed when comparing the ability and ease of formation of tricyclic ether compounds. These results indicate that the later ring system is considerably strained.