Short-step syntheses and complexation properties of Z,Z-tribenzodidehydro- and all-Z-tribenzo[12]annulenes

Syn theses of all/-Z-tribenzo[12]annulenes (1a-c) and Z,Z-tribenzodidehydro[12]annulenes (2a-c) by the reduction of the corresponding tribenzohexadehydro[ I 2]annulenes 3a-c were carried out using a low valent titanium complex generated from Ti(O-iPr)(4) and i-PrMgCl. The unique structure of the first reduction products 2a-c as well as la-c was fully characterized. Complexation of these annulenes with silver(l) ions produces the corresponding silver complexes. Among them, the silver complexes of 2a-c exhibit interesting monomer dimer equilibrium. (c) 2007 Elsevier Ltd. All rights reserved.