Sulfur-rich heterocycles from 2-metalated benzo[b]thiophene and benzo[b]furan: synthesis and structure.
The reaction of 2-lithiated benzo[b]thiophene with 8 equiv of elemental sulfur was found to give pentathiepino[6,7-b]benzo[d]thiophene. In contrast, treatment of 2-lithiated benzo[b]furan with sulfur under similar conditions produced the interesting ring system bis(benzo[4,5]furo)[2,3-e:3',2'-g][1,2,3,4]tetrathiocine. Both of these new cyclic polysulfides were studied by X-ray crystallography. Two polymorphic forms of pentathiepino[6,7-b]benzo[d]thiophene were found, displaying similar conformations but different packing schemes, which was also evident from powder diffraction data.
Unit for Organic Chemistry, CNT, Department of Biosciences at Novum, Karolinska Institute, Novum Research Park, SE-141 57 Huddinge, Sweden.
Tomasz
T
Janosik
Birgitta
B
Stensland
Jan
J
Bergman