Metal mediated cyclooligomerization of mono- and diazulenylethynes

A synthesis of 1,2,4-triazulen-1-ylbenzenes 4a, b as well as di- and tetraazulenylcyclobutadiene cobalt complexes 9a, b and 11a, b by cyclooligomerization of 1-ethynylazulenes 1a, b and 1,2-diazulenylethynes 2a, b are described. (C) 2000 Elsevier Science Ltd. All rights reserved.