Regioselective synthesis of 1-arylindazoles via N-arylation of 3-trimethylsilylindazoles
摘要:
The copper(II)-catalyzed cross-coupling reaction of 3-trimethylsilylindazoles bearing substituents on the benzene ring with arylboronic acids regioselectively gave the corresponding 1-aryl-3-trimethylsilylindazoles and no 2-aryl isomers were formed at all. Moreover, the trimethylsilyl group of the resulting indazoles was easily removed by treatment with ethanolic KOH to give 1-arylindazoles. (c) 2005 Elsevier Ltd. All rights reserved.
[3+2]Cycloadditionreaction of lithium trimethylsilyldiazomethane with benzynes, generated from halobenzenes, gave the corresponding 3-trimethylsilylindazoles in good to moderate yields.
The copper(II)-catalyzed cross-coupling reaction of 3-trimethylsilylindazoles bearing substituents on the benzene ring with arylboronic acids regioselectively gave the corresponding 1-aryl-3-trimethylsilylindazoles and no 2-aryl isomers were formed at all. Moreover, the trimethylsilyl group of the resulting indazoles was easily removed by treatment with ethanolic KOH to give 1-arylindazoles. (c) 2005 Elsevier Ltd. All rights reserved.