Aryliminodimagnesium Reagents. XIX. Effects of Miscellaneous Metal Halides on Oxidative Self-Coupling of the Reagent, and on Its Condensation with Nitrobenzene. A New Preparative Route to o,o'-Dihydroxyazobenzene

Article abstract of DOI:10.1246/bcsj.64.196

Fourteen metal halides (MXn) were each added to the solution of aryliminodimagnesium (p-RC6H4N(MgBr)2, IDMg) in tetrahydrofuran, and the effect of MXn on relative yields of products was examined in the following three IDMg reactions: (A) oxidative coupling leading to symmetrical azobenzene, (B) condensation with nitrobenzene, and (C) condensation with o-hydroxy-substituted (o-HO) nitrobenzene.Reaction A was promoted by addition of CuCl2, and the yield of azoxybenzenes in reaction B was improved by addition of NiCl2 or CdCl2.Reaction C was similarly modified by addition of CdCl2 so as to improve the yield of o-HO-azoxybenzenes.Their acetyl derivatives underwent a facile photoinduced migration of azoxy oxygen and were successively hydrolyzed to afford bidentate chelating agents, o,o'-(HO)2-azobenzenes.