Tetrahedron Letters, Vo1.22, No.3'7, pp 3577 - 3578, 1981 oo40-4039/8l/j?~577-02802.00/0 Printed in Great Britain 01981 Pergamon Press Ltd. GENERATION AND TRAPPING OF 2,3-NAPHTHOQUINONE V. Horak*, F.V. Foster, R. de Levie, J.W. Jones, and P. Svoronos Department of Chemistry Georgetown University Washington, D.C. 20057 Abstract: 2,3_Naphthoquinone generated from 2,3_dihydroxynaphthalene was trapped with cyclopentadiene and its properties examined by dc polarography and cyclic voltametry. 2,3_Naphthoquinone is one of the three missing members in the family of naphthoquinones. Up to the present all attempts of preparation failed and older claims of a successful synthesis were corrected later.1 The study of the oxidation of 2,3_dihydroxynaphthalene with Co3+ followed potentiometrically indicated instability for the primary oxidation product, apparently the 2,3-napthoquinone. The spontaneous chemical transformation of the latter was characterized as polymerization.2 The only physicochemical information which characterizes 2,3_naphthoquinone is the polarographic halfwave potential reported by Horner; 3 however, it is of no value for structural characterization as will be shown later. Even the structurally related l,&diphenyl-2,3-naph- thoquinone generated from the respective dihydroxy compound did not prove higher stability. Depending on the experimental conditions, the isolated pro- duct was either a trimer or, in the presence of butadiene, a Diels-Alder adduct. In this paper the results of our recent studies of the chemical and electrochemical oxidation of 2,3_dihydroxynaphthalene are reported. The oxidation of 2,3_dihydroxynaphthalene with aqueous KI03 and, eventually, in the presence of solvents such as methanol, acetone, and ethyl acetate in a single or two-phase system, produced either a l,l'-dimer (I) already reported in the literature5 or a polymer. The structure of the latter has not yet been fully characterized. The l;l'-dimer (I) was also the exclusive product of an oxidation in the presence of cyclopentadiene in a mix- ture of water with organic solvent, e.g., methanol, acetone, ethyl acetate. However, from the oxidation of 2,3_dihydroxynaphthalene with aqueous KIO3in the presence of a large excess of cyclopentadiene (as a separate phase, in the absence of organic solvents), besides a small quantity of l,l'-dimer, a yellow compound was isolated in 56% yield and identified as compound II, m.p. 170' after crystallization from cyclohexane and vacuum sublimation.