Intramolecular anionic diels-alder reactions of 1-aryl-4-oxahepta-1,6-diyne systems in DMSO.
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.
Kudoh
Takayuki
T
Department of Medical and Bioengineering Science, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama, Japan.
Mori
Tomoko
T
Shirahama
Mitsuhito
M
Yamada
Masashi
M
Ishikawa
Teruhiko
T
Saito
Seiki
S
Kobayashi
Hisayoshi
H
D000466:Alkadienes / Q000138:chemical synthesis* / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry
D000466:Alkadienes; D004987:Ethers; D004121:Dimethyl Sulfoxide