Akiruct: The reactions of the 9-cyanoanthracene dianion generated by the action of hvo equivalents of potassium in liquid ammonia with primary alkyl iodides and bromides Save 9-o-9.1Odialkyl-9, IOdihydroanthracenes. The alkyktion of the 9-cyaao-9,1Odihydm-9-anthryl anion gene&cd by the two-electron reduction of 9-cyanoanthnuxne in liquid ammonia ia the presence of anmwdum chloride Save 9cyano-9-alkyl-9.lO~hydroanthracene. The results obtained by using cyclopropylmethyl bromide as model reagent suggest these tz+ctions to PKIC& through S, mechanism. The spatial strachue of 9.lOdihydmanUuacene derivatives obtained is discussed.
The reduction of aromatic compounds by alkaline metals in liquid ammonia with subsequent protonation or alkylation is a general method for synthesis of dihydro-and alkyldihydroaromatic compounds. The reaction may be performed with various aromatics differing in the substitution degree and the character of substituents (OR, NR2, R, Sie3, COi, COzR, CONR2, COR, Phu, CN4*3. The synthetic outcome of the reaction is determined by the regioselectivity of alkylation and the number of alkyl fragments being introduced; hence it directly depends on the nature, structure and properties of anionic intermediates formed in arene reduction3~7. Some authors have examined the nature of the reduction products of arenes by alkaline metals in liquid amrnoniac7. In the case of aromatic nitriles, it has been shown6, that the basicity of the dianion 1% formed in the reduction of 9-cyanoanthracene 1 by two equivalents of potassium is insufficient for its protonation in liquid ammonia. However, the dianion 12may be converted to the 9-cyano-9,10-diiydro-9-anthryl anion (l-H-) by the action of a stronger protonating agent as compared to ammonia, e.g., by methanol. One can 1 Experiment No.5 performed act. to I. the others act. to II (see Experimental). * Stereoisomer ratio 5: I. 3 InadditiontonitrileI, 130mgofamixhrreofmoncr-anddiallryMibydroderivativesoblisromrd(20%oftbe~amountgf reaction products). 4 Stereoisomer ratio 4: 1.