936916-75-5Relevant academic research and scientific papers
Intramolecular anionic Diels-Alder reactions of 1-aryl-4-oxahepta-1,6-diyne systems in DMSO
Kudoh, Takayuki,Mori, Tomoko,Shirahama, Mitsuhito,Yamada, Masashi,Ishikawa, Teruhiko,Saito, Seiki,Kobayashi, Hisayoshi
, p. 4939 - 4947 (2008/02/03)
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 α-arylallenide anion can be protonated by DMSO, it can be back to the allenide anion probably because of a small acidity difference between α-arylallene and DMSO. The α-arylallenide anion in combination with the α-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.
