title: Intramolecular anionic diels-alder reactions of 1-aryl-4-oxahepta-1,6-diyne systems in DMSO.
abstract: Base-promoted cycloaddition reactions of 1-aryl- or 1-aryl-7-substituted-4-oxahepta-1,6-diyne systems in DMSO have proven to involve an anionic intramolecular Diels-Alder process taking place even at room temperature in spite of the reaction suffering from temporary disruption of aromaticity. Although initially formed alpha-arylallenide anion can be protonated by DMSO, it can be back to the allenide anion probably because of a small acidity difference between alpha-arylallene and DMSO. The alpha-arylallenide anion in combination with the alpha-aryl substituent can constitute an anionic diene structure that undergoes the intramolecular Diels-Alder reaction involving the C(6)-yne part, a very fast process probably because of the increased HOMO-1 level of the anionic diene, as shown by DFT calculations. Diversified substituted naphthalenes, benzofurans, phenanthrenes, and quinolines, including biaryl architectures, are available from 4-oxahepta-1,6-diynes in a highly expeditious way.
authors: Department of Medical and Bioengineering Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama, Japan.
authors: Takayuki
authors: T
authors: Kudoh
authors: Tomoko
authors: T
authors: Mori
authors: Mitsuhito
authors: M
authors: Shirahama
authors: Masashi
authors: M
authors: Yamada
authors: Teruhiko
authors: T
authors: Ishikawa
authors: Seiki
authors: S
authors: Saito
authors: Hisayoshi
authors: H
authors: Kobayashi
mesh_terms: D000466:Alkadienes / Q000138:chemical synthesis* / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry
chemical_list: D000466:Alkadienes; D004987:Ethers; D004121:Dimethyl Sulfoxide