Palladium complexes isocyanides

Cavell KJ, McGuinness DS (2007) Palladium complexes with carbonyl, isocyanide and carbene ligands. In Crabtree RH, Mingos DMP, Canty AJ (eds) Comprehensive organometallic chemistry 111. Elsevier, Amsterdam... 

Dixon, K. R. Dixon, A. C. Palladium Complexes with Carbonyl, Isocyanide and Carbene Ligands, In Comprehensive Organometallic Chemistry II A review of the literature 1982-1994 Puddephatt, R. J. Ed., Elsevier, 1995, Vol. 9, p 193. 

The indazoline products can also be made directly from the palladium complexes 78 by heating them with the isonitrile in toluene at 120CC.162 They are also formed in dicobalt octacarbonyl-catalyzed reactions of azo-arenes with isocyanides but in this case an alternative reaction pathway leading to indazolo[2,l- ]indazoles (79) is observed (Scheme 96).163 Products of the latter type are formed from sterically hindered isocyanides hence it is likely that in these cases a double metallation is favored over isocyanide insertion into a monometallated species (Scheme 97). 

Addition of disilanes to isocyanides is catalyzed by palladium complexes, giving A-substituted bis(silyl)imino-methanes (Equation (53)).132 A wide range of isocyanides including aryl isocyanides and alkyl isocyanides can take part in the reaction. However, it is important to note that tert-alkyl isocyanides hardly undergo the bis-silylation reaction. This low reactivity of / r/-alkyl isocyanides allows their use as spectator ligands in the catalytic bis-silylations. 

C2H,N, Pyridine, 3,5-dimethyl-palladium complex, 26 210 CbHsNO, Benzoyl isocyanide chromium com-C HbO, Ethanone, 1-phenyl-manganese complex, 26 156-158 CBH, 02, Methyl benzoate chromium complex, 26 32 C H i, o-Xylylene magnesium complex, 26 147 ChH P, Phosphine, dimethylphenyl-iron complex, 26 61 ruthenium complex, 26 273 ChH12, 1,5-Cyclooctadiene iridium complex, 26 122 ruthenium complexes, 26 69-72, 253-256 ChH OjPS, 2-Butenedioic acid, 2-(dimethylphosphinothioyl)-dimethyl ester, manganese complex, 26 163... 

Balch ei al. (306) have given a detailed report on novel A-frame-type methylene bridged palladium complexes of composition Pd2(dpm)2( p-CHR)X2 (X = I, Br, Cl R = H, CH3) and [Pd2(dpm)2(joi-CH2)L2]2+ (L = pyridine, methylisocyanide). It was demonstrated that the Pd—C (methylene) bond resists insertion of carbon monoxide, isocyanides, or sulfur dioxide. Protonation of Pd2(dpm)2(/x-CH2)I2 with fluoroboric acid yields the compound [Pd2(dpm)2(ju.-I)(CH3)I]BF4 in which the bridging methylene group of the precursor has been converted into a terminal methyl group, a process that has also been encountered in a previous example (52). 

Activation of two Si—Si bonds in bis(disilanyl)alkanes with palladium(O) bis(tert-alkyl isocyanide) induced the formation of the cyclic bis(silyl)palladium(II) bis(terf-alkyl isocyanide) complexes (100) and disilanes described schematically in Scheme 42. These complexes were found to react with phenylacetylene, affording different amounts of five-membered cyclic products and acyclic products which are derived from the insertion of the alkyne into the general intermediate complex 101 (Scheme 42, equation 54). The bis(silanyl)dithiane palladium complex (102) was isolated and characterized in the solid state the two silicon atoms, the two isocyano carbons and the palladium atom are nearly in a plane with a short cross-ring Si—Si distance of 2.613(2) A, suggesting the possibility of covalently bonded two Si—Si atoms in the four-membered ring. Similar reaction with cyclic disilanes afforded oligomers, and cyclic 20-membered compounds have been prepared in the presence of nitriles248,249. 

In the reactions of episulfides ring opening usually occurs, as in the reaction between palladium(Il) isocyanide complexes of type 165 (L =... 

The first multiple insertion of isocyanide into the Pd-C bond of organopal-ladium complexes was reported by Yamamoto in 1970 (Scheme 21) [30]. The reaction of one, two, and three equivalents of cyclohexyl isocyanide with the trans-iodobis(phosphine)methylpalladium(II) complexes 17 yielded the monoimino (18), bisimino (19), and trisimino (20) palladium complexes, re-... 

However, formation of stable iminoacyl complexes does not always prevail in the competition reaction systems involving CO and isocyanide. Cationic methyl-palladium complexes bearing isocyanides react with CO under ambient conditions to give the corresponding acetylpalladium complexes through CO insertion and not the iminoacylpalladium complexes as shown in Scheme 7.14 [61b],... 

Related reactions of thiolate anions with ort/zo-chloromethyl-phenyl(diphenyl)phosphine have provided a range of ort/ o-alkyl and aryl-thiomethylphenyl(diphenyl)phosphines. " The reactions of 2-amino-alkylphosphines with isocyanates and isothiocyanates have provided routes to new chiral phosphinoalkyl-urea and -thiourea ligands. Similarly, treatment of hydroxy- or amino-functional arylphosphines with isocyanides in the presence of a cyclooctadienepalladium(II) complex results in the formation of bidentate arylphosphino-carbene palladium complexes. New chiral phosphinoarylphosphoramidite ligands, e.g.,... 

Silylboration and borylstannation of acetylenes have also been achieved easily in the presence of a catalyst of palladium complexes. In contrast, palladium complexes such as Pd(PPh3)4 or Pd(OAc)2-isocyanide were ineffective for diboration of alkynes. However, the development of another new ligand will solve this difficulty in the future. 

Reactions.—Desulphurization of thiirans to alkenes remains an important strategy for the preparation of hindered alkenes, e.g. (14), and is the most typical thiiran reaction. Phosphines and phosphites are the reagents that are most often used. Lithium reagents desulphurize rra s-2,3-diphenylthiiran to ( )-stilbene, while the ds-isomer is converted into a 1 1 mixture of (Z)-stilbene and the two isomers of tr-mercaptostilbene. 2-Phenylthiiran is desulphurized by cf-metallated isocyanides. Thermal extrusions of sulphur include the conversion of (15) into (16), amongst others. Desulphurizations using zinc and acetic acid, molybdenum or palladium complexes, and the oxaziridine (17) have been reported. 

Palladium Complexes with Carbonyl, Isocyanide, and Carbene Ligands ... 

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