Synthesis and Reactivity toward Isonitriles of (2-Aminoaryl)palladium(II) Complexes

Abstract

Mixtures of “Pd(dba)2” (dba = dibenzylideneacetone) and 2,2‘-bipyridine (bpy; 1:2) or N,N,N‘,N‘-tetramethylethylenediamine (tmeda; 1:1) react with 2-bromo-4-nitroaniline to give [Pd{C6H3NH2-2-NO2-5}Br(N−N)] (N−N = bpy (1b), tmeda (1b‘)). Reactions of 2-iodoaniline with mixtures of “Pd(dba)2” and isonitriles RNC (R = C6H3Me2-2,6 (Xy), 2:1:2 molar ratios; R = tBu, 2.9:1:2 molar ratios) result in the formation of the complexes [Pd{κ2 C,N-C(NXy)C6H4NH2-2}I(CNXy)] (2a) and trans-[Pd{C(NtBu)C6H4NH2-2}I(CNtBu)2] (3a*). The reactions of [Pd{C6H4NH2-2}I(bpy)] and 1b‘ with RNC give the complexes trans-[Pd{C(NR)C6H3NH2-2-Y-5}}X(CNR)2] (Y = H, X = I, R = Xy (3a), tBu (3a*); Y = NO2, X = Br, R = Xy (3b), tBu (3b*)). Complexes 3 react with Tl(TfO) (TfO = CF3SO3) to give decomposition products, with the exception of 3a, which gives the cyclopalladated complex cis -[Pd{κ2 C,N-C(NXy)C6H4NH2-2}(CNXy)2]TfO (4a). Complex 2a or 3 reacts with Tl(TfO) in the presence of the corresponding ligand, L or L2, to give the cationic complex [Pd{C(NR)C6H3NH2-2-Y-5}(CNR)L2]TfO (L = tBuNC, Y = H (5a*), NO2 (5b*); L2 = bpy, Y = H, R = Xy (6a), tBu (6a*)). When L = PPh3, the resulting complexes trans-[Pd{C(NR)C6H3NH2-2-Y-5}(CNtBu)2(PPh3)]TfO (Y = H (7a*), NO2 (7b*)) decompose easily to the Pd(I) complex [Pd2(CNtBu)4(PPh3)2](TfO)2 (8). The reaction of 2a with Tl(TfO) affords [{Pd[κ2 C,N-C(NXy)C6H4NH2](CNXy)}2(μ-I)]TfO (9a), and that with a mixture of bpy and Tl(TfO) in acetone with subsequent bubbling of CO through the solution gives [Pd(R)(CNXy)(bpy)](TfO)2 (10), where R is 2-(xylylamino)-3-xylylquinazolinium-4-yl. The crystal structures of 2a, 3a, 4a, 6a, 8, 9a·CH2Cl2, and 10·1.5CH2Cl2 have been determined by X-ray diffraction studies. Some hydrogen bond interactions (Csp 3 −H···Pd, N−H···π−arene, N−H···I−Pd; eight-membered rings ···O−S−O···H−N−C−C−H··· and ···I−Pd−N−H···I−Pd−N−H···) lead to interesting supramolecular structures.

Synthesis and Reactivity of Ortho-Palladated Phenylacetamides. Intramolecular C−N vs C−O Reductive Coupling after CO or XyNC Insertion into the Pd−C Bond. Synthesis of Isoquinoline- and Isocoumarin-Based Heterocycles

“…Aryl derivatives of the type [Pd- 11.7373 (5) 13.5328 (7) 13.6966 (5) 13.4080(6) c (Å ) 17.4652 (8) 14.1804 (7) 14.0469 (5) 16.7547 (7) ), which result from the displacement of the iodo ligand by the nitrogen of the anionic amidate group and were isolated in moderate to good yields. When NEt 3 was used instead, deprotonation of the amide occurred only to a small extent, as detected by NMR.…”

“…We report also a systematic study of the reactions of these aryl complexes with CO and XyNC (Xy = 2,6-dimethylphenyl). This type of reactions have been widely studied, as they are involved in the synthesis of acyl [10][11][12][13][14][15] and iminoacyl 11,[13][14][15][16][17][18][19][20] palladium complexes and also in many stoichiometric and catalytic syntheses of organic compounds. [13][14][15][20][21][22] We report in this work that, depending on the substituents on the amidic nitrogen, these insertion reactions lead to isoquinoline-or isocoumarin-based heterocycles resulting from intramolecular C-N or C-O couplings.…”

Synthesis and Reactivity of Ortho-Mercuriated and Ortho-Palladated Arylacetals and Cyclic and Acyclic Aryldithioacetals. New Examples of the Rearrangement of Acyclic Dithioacetal Aryl- to Dithioether Alkyl-Palladium Complexes

“…22 We have reported the synthesis of ortho-palladated complexes by transmetalation reactions, using arylmercurials, by oxidative additions of the corresponding haloarenes to palladium(0) species, or through orthopalladation processes. The first method has allowed us to prepare aryl-palladium complexes bearing CHO, [23][24][25] etamidic acids, 39 and with CO to give aroyl-palladium complexes, [28][29][30][31]37, 39 3-methylenephthalides and 3-ethoxy-3-methyl-3H-isobenzofuran-1-one 39 or, in the presence of O 2 , palladium benzoate complexes. 28,29 We have reported that certain 2,3,4-trimethoxy-6-formylphenylpalladium complexes undergo a rare rearrangement, involving a positional change between the formyl group and the palladium moiety with breaking and reforming of C-C and C-Pd bonds, to give the corresponding 3,4,5-trimethoxy-2-formylphenylpalladium isomers (Chart 1).…”

Mono- and Dipalladated Derivatives of 2,5-Distyrylbenzene. Reactivity toward XyNC and Alkynes. Synthesis of Complexes with Indacenediide Ligands

“…Although the insertion reactions of isocyanides into Ar−Pd bonds have been extensively investigated, 4,9,[11][12][13][14][15][16][17][18][19][20][25][26][27]30,33,78,79 this is the first report of the simultaneous insertion of isocyanide into two aryl−Pd bonds on the same benzene ring of a complex. trans,trans-2,5-distyryl-2,4-dibromobenzene 80 to 2 equiv of [Pd(dba) 2 ] in the presence of tbbpy or tmeda (Scheme 1).…”