Aryl triflates: useful coupling partners for the direct arylation of heteroaryl derivatives via Pd-catalyzed C–H activation–functionalization
作者:Julien Roger、Henri Doucet
DOI:10.1039/b715235c
日期:——
Aryl triflates were found to be suitable partners for the palladium catalyzed directarylation of heteroaromatics via C-H activation-functionalization. The reaction conditions and the catalyst have a determining influence on the yields. The system combining PPh3 and Pd(OAc)2 using KOAc as base and DMF as solvent promotes the selective 2- or 5-arylations in moderate to high yields. Several heteroaromatics
Ong Chi Wi, Chen Chong Ming, Juang Shyh Shian, J. Org. Chem, 59 (1994) N 25, S 7915- 7916
作者:Ong Chi Wi, Chen Chong Ming, Juang Shyh Shian
DOI:——
日期:——
Dienediones as Building Blocks of an Unfused Polyaromatic Furan Ring System with Tunable Regioselectivity
作者:Chi Wi Ong、Chong-Ming Chen、Shyh Shiaan Juang
DOI:10.1021/jo00115a032
日期:1995.5
The 1,6-dioxo (E,E)-diene has two available sites for isomerization td the (Z) configuration and can undergo an intramolecular acid-catalyzed cyclization to furanonium intermediates A and B, giving two distinct regioisomeric cyclized products. With unsubstituted aryl derivatives, unfused polyaromatic furans were obtained in good yield with HCl-AcOH. Aryl groups having electron-withdrawing substituents were found to give the opposite regioselectivity. In contrast, the reaction in p-TsOH-CH2Cl2 always resulted in a mixture of regioisomeric products, irrespective of the aryl substituents. Thus, the regioselectivity in the intramolecular cyclization of 1,6-dioxo 2,4-diene can be tuned by varying the aromatic substituents and the acid conditions.