Synthesis of symmetrical bisquinolones via nickel(0)-catalyzed homocoupling of 4-chloroquinolones

Abstract

A method for the gram-scale preparation of functionalized 4,4′-bisquinolones using a microwave-assisted Ullmann-type homocoupling reaction is described. The method is catalytic in nickel(O) which is generated in situ by reduction from an inexpensive nickel(II) source and utilizes readily available 4-chloroquinolin-2(1H)-ones as starting materials. In contrast to the alternative palladium(0)-catalyzed one-pot borylation/Suzuki crosscoupling reaction, the new method avoids the use of an expensive catalyst and cross-coupling partner such as bis(pinacolato)diboron. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA,.