Palladium-Catalyzed Amination of 2-Iodo-<i>para</i>-carborane

Abstract

The palladium-catalyzed Buchwald−Hartwig amination of B-iodocarborane by various azoles and amines is described for the first time. The reactions of 2-iodo- p -carborane with indole, imidazole, benzimidazole, or carbazole in the system Pd(dba) 2 −BINAP−Bu t ONa in dioxane at 100 °C gave 2- p -carboranyl derivatives of these azoles in high yields together with 2-hydroxy- p -carborane as a side product. The reactions of 2-iodo- p -carborane with aromatic amines in the same system gave the amination products in 60−70% yields and also were accompanied by the formation of hydroxy derivatives (up to 30% yields). In a special investigation it was shown that the base Bu t ONa was responsible for its formation. The principle possibility of the amination of 2-iodo- p -carborane by morpholine (with 30% yield) as an example of aliphatic amination was shown. The structures of N -(1,12-dicarba -closo -dodecaboran-2-yl)carbazole ( 1 ), N -(1,12-dicarba -closo -dodecaboran-2-yl)benzimidazole ( 2 ), N -(1,12-dicarba -closo -dodecaboran-2-yl)indole ( 4 ), and 2-hydroxy-1,12-dicarba -closo -dodecaborane ( 5 ) have been established by X-ray diffraction studies.