Simple and productive routes to mono-, di- and triethynylazulenes are descr
ibed. Azulenes ethynylated in the five-membered ring can be prepared on a m
ultigram scale by Pd-catalyzed cross-coupling of iodo- or bromoazulenes wit
h trimethylsilyl-acetylene and subsequent desilylation. 5,7-Diethynylazulen
e was synthesized by dibromomethylenation of the corresponding dialdehyde a
nd subsequent dehydrobromination. (C) 2000 Elsevier Science Ltd. All rights
reserved.