@article{724187,
      recid = {724187},
      author = {Zhang, Shaoguang,},
      title = {The chemistry of zirconacycles and  2,6-diazasemibullvalenes synthesis, structures, reactions,  and applications in the synthesis of novel N-heterocycles /  [electronic resource] :},
      pages = {1 online resource (xi, 173 pages) :},
      note = {"Doctoral thesis accepted by Peking University, Beijing,  China."},
      abstract = {In this thesis, the author introduces two strategies used  to construct various types of N-heterocycles, based on the  chemistry of zirconacycles and 2,6-diazasemibullvalenes. In  the first part, the author presents the development of  multi-component cyclization of a  zirconacyclobutene-silacyclobutene fused compound, nitriles  and unsaturated compounds. These reactions provide  synthetically useful methodology for various N-heterocycles  such as 3-acyl pyrrole, pyrrolo[3,2-d]pyridazine and  dihydropyrroloazepine, which are all difficult to  synthesize by other means. The isolation and  characterization of the key three-fused-ring  Zr/Si-containing intermediates are also described in  detail. These results show that the  zirconacyclobutene-silacyclobutene fused compound behaves  as a ℓ́ℓchemical transformerℓ́ℓ upon treatment with various  substrates via the ℓ́ℓcoordination-induced skeleton  rearrangementℓ́ℓ mechanism. In the second part, the author  demonstrates the synthesis and isolation of a series of  2,6-diazasemibullvalenes (NSBVs) from the reaction of  1,4-dilithio-1,3-dienes and nitriles, highlighting the  significant progress made for the first time in this work:  (1) determination of X-ray crystal structure of a  substituted 2,6-diazasemibullvalene; (2) measurement of the  activation barrier of its rapid intramolecular aza-Cope  rearrangement in solution; (3) exploration of several  reaction types of NSBV with diverse ring-expansion products  and ℓ́ℓbowl-shapeℓ́ℓ or ℓ́ℓcage-shapeℓ́ℓ N-containing  polycyclic skeletons; (4) demonstration of the localized  structure as the predominant form and the homoaromatic  delocalized structure as a minor component in the  equilibrium using theoretical analysis. Based on  well-founded results, this work sheds new light on this  controversial topic.},
      url = {http://library.usi.edu/record/724187},
      doi = {https://doi.org/10.1007/978-3-662-45021-5},
}