Beirut Reaction Experimental

Perhaps one of the most exciting developments in the chemistry of quinoxalines and phenazines in recent years originates from the American University of Beirut in Lebanon, where Haddadin and Issidorides first made the observation that benzofuroxans undergo reaction with a variety of alkenic substrates to produce quinoxaline di-AT-oxides in a one-pot reaction which has subsequently become known as the Beirut reaction . Many new reactions tend to fall by the wayside by virtue of the fact that they are experimentally complex or require starting materials which are inaccessible however, in this instance the experimental conditions are straightforward and the starting benzofuroxans are conveniently prepared by hypochlorite oxidation of the corresponding o-nitroanilines or by pyrolysis of o-nitrophenyl azides. 

The ambivalent role of metal chlorides, which may act as Lewis acids or electron donors, in ring-opening reactions of 2//-aziridines by imines, enaminones, and enam-inoesters to form imidazoles, pyrroles, and pyrrohnones has been discussed. Experimental and theoretical mechanistic studies of the Davis-Beirut reaction, whereby 2//-indazolenes are obtained from o-nitrosobenzaldehydes and primary amines, implicate o-nitrosobenzylidine imine as a pivotal intermediate in the Nfl-bond formation. 

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