- Bulletin of the Chemical Society of Japan (ISSN:00092673)
- vol.86, no.1, pp.129-137, 2013-01-15 (Released:2013-01-15)
The reaction of mesitylene with ethyl propiolate in the presence of [Pd(dppe)(OAc)2] in TFA at 30 °C for 5 h gave diethyl (2E,4Z)-4-[(2,4,6-trimethylphenyl)methylene]-2-pentenedioate selectively. Screening several bidentate phosphines ligands showed that dppe and dppm ligands are good for the arylbutadiene formation. This reaction was applied to other electron-rich arenes and found to be effective for synthesis of arylbutadienes and extended π-conjugated molecules. The regio- and stereoselective addition of an arene to propiolate was confirmed by NMR and single-crystal X-ray structural analyses of the products, suggesting that the arylbutadiene formation consisted of anti addition of an arene and a metal to the triple bond of ethyl propiolate, followed by syn addition to another molecule of ethyl propiolate. Similarly, the reaction of various arenes with ethyl propiolate in the presence of [Pt(dppe)(OTf)2] catalyst gave arylbutadienes selectively. In the Pd- or Pt-catalyzed reaction of arenes with ethyl propiolate, it was found that a bidentate ligand controlled the reaction to lead the formation of arylbutadienes.