FORMATION OF 3,5-DIPHENYL-2-THIABICYCLODEC-Δ1,6-ENE UNDER THE CONDITIONS OF THE PUMMERER REACTION AND ITS STRUCTURE

Article abstract of DOI:10.1007/BF00513161

The Pummerer rearrangement was investigated in the case of 3,5-diphenyl-2-thiabicyclo<4.4.0>decane S-oxide.It is shown that, of the two possible isomers, this compound forms only 3,5-diphenyl-2-thiabicyclo<4.4.0>dec-Δ^1,6-ene under the conditions of the Pummerer reaction; a secondary transformation, viz., disproportionation of the latter to 3,5-diphenyl-2-thiabicyclo<4.4.0>decane and 2,4-diphenyl-5,6-tetramethylenethiopyrylium acetate, is observed. 3,5-Diphenyl-2-thiabicyclo<4.4.0>dec-Δ^1,6-ene was subjected to an x-ray diffraction study; it was proved unambiguously that the C₁=C₆ double bond has a lenght of 1.335 Angstroem and that the dihydrothiopyran and cyclohexene rings have a distorted half-chair conformation: the dihedral angles between the phenyl rings and the planar fragment of the heteroring are 76.8 and 93.2 deg C.