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Communication | Regular issue | Vol 38, No. 8, 1994, pp.1707-1710
Published online, 1st January, 1970
DOI: 10.3987/COM-94-6745
Methylation of Tetrazathiapentalenes (10-S-3 Sulfurane) Fused with Pyridine and/or Pyrimidine Rings and Restricted Rotation of the Pyrimidine Ring: Chemical Evidences for N-S-N Hypervalent Bond

Katsuo Ohkata, Kazuhiro Yamamoto, Minoru Ohsugi, Mika Ohsawa, and Kin-ya Akiba*

*1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan, Faculty of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan


Methylation of the title compounds (10-S-3 sulfurane: 1-3) took place exclusively on the nitrogen at 3(4)-position and selectively on the nitrogen bound to the more electron-withdrawing heterocycle. The activation energy of the hindered rotation in 5 was lower for the pyrimidine ring (DGc = 20.2 kcal mol-1) bound to the methylated nitrogen than the other one (DGc = 22.9 kcal mol-1).