A new antiaromatic compound: 1,4-biphenylenequinone synthesis and trapping reactions: can a quinone unit stabilize the cyclobutadiene?


Kilic H., Balci M.

TETRAHEDRON, vol.57, no.49, pp.9889-9897, 2001 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 57 Issue: 49
  • Publication Date: 2001
  • Doi Number: 10.1016/s0040-4020(01)01008-0
  • Journal Name: TETRAHEDRON
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.9889-9897
  • Keywords: biphenylenequinone, cyclobutadiene, singlet oxygen, Diels-Alder reactions, nucleus-independent chemical shifts values, BICYCLIC ENDOPEROXIDES, <4>ANNULENE SYSTEM, BIPHENYLENE

Abstract

The photooxygenation of 4a,8b-dihydrobiphenylene affords an endoperoxide. NEt3-catalyzed rearrangement of this endoperoxide gave the corresponding hydroxy enone, while the CoTPP-catalyzed rearrangement afforded a bisepoxide. MnO2 oxidation of hydroxy enol leads to 4a,8b-dihydrobiphenylene-1,4-dione. The NIBS bromination of this dione produces mono- and dibromides. NEt3-supported elimination of monobromide and zinc elimination of dibromide afforded the target compound, 1,4-biphenylenequinone, which was trapped as the dimer and cycloadducts with cyclopentadiene and anthracene, respectively. Furthermore, 1,4-biphenylenequinone was generated upon oxidation of biphenylene-1,4-diol with bis(trifluoroacetoxy)iodobenzene (PIFA). The stability and reactivity of the title compound is discussed. (C) 2001 Elsevier Science Ltd. Ail rights reserved.