Palladium-Catalyzed Amination of 2-Iodo-para-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-pcarboranyl 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) 4), and 2-hydroxy-1,12-dicarba-closo-dodecaborane (5) have been established by X-ray diffraction studies.

Synthesis and Characterization of 2‐Mono‐ and 1,2‐Diaminocarba‐closo‐dodecaborates M[1‐R‐2‐H2N‐closo‐CB11H10] (R=H, Ph, H2N, CyHN)

“…[54] In the isomer 5 the carbon-nitrogen bond length is 1.457(5) . This value compares well to the sum of the covalent radii of carbon and nitrogen (1.47 ) [55] and to the dA C H T U N G T R E N N U N G (CÀN) values in related aminocarba-closo-dodecaborate derivatives: (4) ), [14] [Ph 4 P][1-H 2 N-4,6-(HO) 2 -CB 11 F 9 ] (1.443(4) ), [14] and [Me 4 N][1-Me 2 N-closo-CB 11 H 11 ] (1.452 ).…”

Dicarba‐closo‐dodecaboranes with One and Two Ethynyl Groups Bonded to Boron

“…[15] Thereafter, other dicarba-closododecaboranes with alkynyl substituents bonded to boron have been described that were either synthesized following a Kumada-type reaction protocol or a related coupling procedure. [17][18][19][20] Furthermore, cross-coupling reactions were employed for the preparation of other {closo-C 2 B 10 } derivatives with various substituents bonded to boron, for example, by means of a carbon [9,11,15,[17][18][19][20][21][22] or a nitrogen [23] atom. In this contribution, the syntheses of the diethynyldicarba-closo-dodecaboranes 1,2-R 2 -9,12-(HCC) 2 -closo-1,2-C 2 B 10 H 8 [R = H (1a), Me (2a)] and 9,10-(HCC) 2 -closo-1,7-C 2 B 10 H 10 (3a) and their NMR and vibrational spectroscopic data are presented.…”

Visible‐Light‐Promoted Photocatalytic B−C Coupling via a Boron‐Centered Carboranyl Radical: Facile Synthesis of B(3)‐Arylated o‐Carboranes

“…[18] However,t he substrate scope is limited to arenes bearing benzylic C À Hb onds.R elatively lower yields coupled with competitive side reactions (Diels-Alder reactions) further restrict its synthetic application. [19] Inspired by the photocatalytic transformations of aryl diazonium salts into the corresponding aryl radicals, [20] we wondered whether ab oron-centered carboranyl radical (o- 4 ], 1; [18] Scheme 1). [19] Inspired by the photocatalytic transformations of aryl diazonium salts into the corresponding aryl radicals, [20] we wondered whether ab oron-centered carboranyl radical (o- 4 ], 1; [18] Scheme 1).…”

“…In addition, such an aromatic ene reaction is not compatible with heteroarenes.T othe best of our knowledge,there has been no example on the synthesis of 3-heteroaryl-o-carboranes in the literature. [19] Inspired by the photocatalytic transformations of aryl diazonium salts into the corresponding aryl radicals, [20] we wondered whether ab oron-centered carboranyl radical (o- 4 ], 1; [18] Scheme 1). Herein, we describe the generation of such ac arboranyl radical by photoredox catalysis and its reactions with (hetero)arenes for high-yielding syntheses of 3-(hetero)aryl-o-carboranes.…”