dehydrogenative direct radical arylation of coumarins with arylboronicacids to afford 3-arylcoumarin derivatives is described. A similar reaction system is also applicable to the 3-arylation of quinolinone derivatives. These KMnO4/AcOH-mediated coupling reactions occur regioselectively at the C3 position of coumarins and quinolinones. Some notable features of this method are high efficiency, moderate
A Complete Switch of the Directional Selectivity in the Annulation of 2-Hydroxybenzaldehydes with Alkynes
作者:Huiying Zeng、Chao-Jun Li
DOI:10.1002/anie.201407589
日期:2014.12.8
reaction selectivity is an eternal pursuit for chemists working in chemical synthesis. As part of this endeavor, our group has been exploring the possibility of constructing different natural product skeletons from the same simple starting materials by using different catalytic systems. In our previous work, an isoflavanone skeleton was obtained from the annulation of a salicylaldehyde and an alkyne
Cute CO! An interesting and straightforward procedure for the carbonylativesynthesis of chromenonesfrom readily available salicylicaldehydes and benzylchlorides has been developed (see scheme; DPPP=1,3‐bis(diphenylphosphino)propane). In the presence of a palladium catalyst, various coumarins were produced in good to excellent yields.
Three-component coupling using arynes and DMF: straightforward access to coumarins via ortho-quinone methides
作者:Hiroto Yoshida、Yu Ito、Joji Ohshita
DOI:10.1039/c1cc11955a
日期:——
ortho-Quinone methides, arising from a formal [2+2] cycloaddition between arynes and DMF, were found to facilely undergo a [4+2] cycloaddition with ester enolates or ketenimine anions to produce diverse coumarins in a straightforward manner.