Pyridazine derivatives.: Part 33:: Sonogashira approaches in the synthesis of 5-substituted-6-phenyl-3(2H)-pyridazinones

Several 6-phenyl-3(2H)-pyridazinones bearing different alkynyl groups at position 5 have been prepared by a palladium-catalysed Sonogashira cross-coupling reaction. An interesting base-promoted electronically permitted isomerization has been observed during the coupling of 1-phenyl-2-propyn-1-ol. This rearrangement afforded the E-chalcone 6 in excellent yield. (C) 2003 Elsevier Science Ltd. All rights reserved.