Organic Synthesis by Means of Metal Complexes. X1Copper Catalyzed Oxidation of o-Phenylenediamine to Mucononitrile

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Abstract
This paper describes a simple stereospecific synthesis of cis,cis-mucononitrile and its derivatives in hig hyields. The procedure is based on the oxidation of o-phenylenediamine derivatives with molecular oxygen catalyzed by cuprous salts. Oxidative coupling of aniline with molecular oxygen catalyzed by cuprous chloride gives azobenzene2. Also it is known that o-phenylenediamine (PDA) is oxidized in the presence of ferric3, Cobaltous4, and cupric chlorides5to afford 2,3-diaminophenazine or 2-amino-3oxophenazine. The formation of a metal nitrogen bonded intermediate, followed by intermolecular reaction was postulated in these oxidation reactions.6,7.Mechanistic consideration of these reactions leads us to expect that the oxidation of PDA with molecular oxygen under selected conditions should proceed intramolecularly with ring claevage to give mocononitrile(MNL). PDA is converted into MNL by using stoichimetricamount of nickel peroxide8or lead terraacetate9, but the yields are low. We now wish to report a selective oxidative ring cleavage of PDA. rather than the phenazine formation, to give MNL in a very high yield.