Palladium tetra

J. H. Darling, and J. S. Ogden, Infrared Spectroscopic Evidence for Palladium Tetra-carbonyl, Inorg. Chem. 11, 666-667 (1972). 

Pt and Pd supported on silica or active carbon are prepared by a cationic exchange technique, using an aqueous solution of platinum or palladium tetra-mine hydroxide, Pt(NH3)4(OH)2 and Pd(NH3)4(OH)2, following the procedure already described [94]. 

Benzyloxy-6-bromo-4-nitro-JV-(2-propeny])aniline (5.82 g, 16 mmol), tetra-ii-butylammonium bromide (5.16 g, 16 mmol) and titjN (4.05 g, 40 mmol) were dissolved in DMF (15 ml). Palladium acetate (72 mg, 2 mol%) was added and the reaction mixture was stirred for 24 h. The reaction mixture was diluted with EtOAc, filtered through Cclite, washed with water, 5"/o HCl and brine, dried and evaporated in vacuo. The residue was dissolved in CHjClj and filtered through silica to remove colloidal palladium. Evaporation of the eluate gave the product (4.32 g) in 96% yield. 

Trimethylsiloxyphenyl isocyanide enters the cyclization reaction with [MCl2(NCPh)2] (M = Pt, Pd) to yield the homoleptic tetracarbenes 77 (M=Pt, Pd) (97JOM(541)51). Complex 77 (M = Pd) enters an interesting reaction with ammonia to yield the species 78 where two of this benzoxazol-2-ylidene ligands are deprotonated and become C-coordinated benzoxazole moieties, while the other two remain intact. Palladium(II) iodide in these conditions behaves differently yielding the di-Mo-cyanide complex, which in the presence of tetra- -butyl ammonium fluoride gives the dicarbene 79. 

Hydrogenation of exocyclic, pyranoid vinyl ethers could afford a mixture of both possible 6-deoxy-D and L-hexoses. Our observations show that the proportion of each isomer is dependent upon the catalyst and the substituents on the vinyl ether. Thus, treatment of a methanol solution of l,2,3,4-tetra-0-acetyl-6-deoxy-/ -D-xylo-hex-5-eno-pyranose (12) with hydrogen in the presence of a palladium catalyst afforded a mixture which was shown by gas chromatography to contain 96% of the 6-deoxy-D-gluco isomer (11) and 4% of the 6-deoxy-L-ido isomer (13). In this... 

During the course of an elegant synthesis of the multifunctional FR-900482 molecule [( )-43, Scheme 9], the Danishefsky group accomplished the assembly of tetracycle 42 using an intramolecular Heck arylation as a key step.24 In the crucial C-C bond forming reaction, exposure of aryl iodide 41 to a catalytic amount of tetra-kis(triphenylphosphine)palladium(o) and triethylamine in acetonitrile at 80 °C effects the desired Heck arylation, affording 42 in an excellent yield of 93 %. The impressive success of this cyclization reaction is noteworthy in view of the potentially sensitive functionality contained within 41. 

PdF4 is the only stable palladium(IV) halide [18] (testimony to the oxidizing nature of palladium(IV)) and is a very moisture-sensitive diamagnetic red solid the structure is based on Pd6F24 hexameric units linked three-dimensionally. It has octahedrally coordinated palladium with two terminal (cis) fluorines and four bridging ones. Despite the absence of other tetra-halides, the complete series of PdX - exist (cf. Ir). 

Alkenylboranes (R2C=CHBZ2 Z — various groups) couple in high yields with vinylic, alkynyl, aryl, benzylic, and allylic halides in the presence of tetra-kis(triphenylphosphine)palladium, Pd(PPh3)4, and a base to give R C CHR. 9-Alkyl-9-BBN compounds (p. 1013) also couple with vinylic and aryl halides " as well as with a-halo ketones, nitriles, and esters.Aryl halides couple with ArB(IR2 ) species with a palladium catalyst. ... 

RUQPIC RUQPIC01 TOTSEA catena((/z2-Diiodo)-l,3,5-trithiacyclohexane) 1.3.5- Trithiacyclohexane (diiodine) Bis(tetra-n-butylammonium) bis(2-dicyanomethylene- 4.5- disulfanylcyclopent-4-ene- l,3-dionate)-palladium iodine... 

Jerome-Lerulte, S. Vibrational Spectra and Structural Properties of Complex Tetra-cyanides of Platinum, Palladium and Nickel. Vol. 10, pp. 153—166. 

The palladium(II) phthalocyanines are satisfactory singlet oxygen generators. Thus, f>A values for tetra-t-butylphthalocyanine ((27), with stated replacement for Mg) are 2H, 0.22 Zn, 0.34 Pd, 0.54, i.e., increasing in line with the heavy atom effect.180 For palladium(II) tetra-t-butylphthalocyanine ((27), Pd instead of Mg) in benzene at 290 K, 4>f= 0.048 and X = 0.49.180 However, palladium(II) 2,3-dihydroxy-9,16,23-tri-t-butylphthalocyanine was synthesized by a mixed condensation (1 9 mix of appropriate dinitriles) as a likely amphiphilic sensitizer, but did not show bioactivity in an enzyme assay, possibly because of aggregation.180... 

A palladium catalyst is used in the transformation of a siloxyfuran to a phenyl substituted furanone <00JCS(P1)3350>. Similar products, furan-2(5//)-one derivatives, are afforded through the reaction of tetra-n-butylammonium fluoride with the corresponding substituted 2-siloxyfuran <00S1878>, as well as the oxidation of 3,4-disubstituted furans by singlet oxygen . 

Leadbeater NE, Pillsbury SJ, Shanahan E, Williams VA (2005) An assessment of the technique of simultaneous cooling in conjunction with microwave heating for organic synthesis. Tetrahedron 61 3565-3585 Lee CKY, Holmes AB, Ley SV, McConvey IF, Al-Duri B, Leeke GA, Santos RCD, Seville JPK (2005) Efficient batch and continuous flow Suzuki crosscoupling reactions under mild conditions, catalysed by polyurea-encapsulated palladium (II) acetate and tetra-n-butylammonium salts. J Chem Soc Chem Commun 2175-2177... 

Denmark and Kallemeyn have described the mild palladium-catalyzed insertion of 1,2-diethoxy-1,1,2,2,-tetra-methyldisilane EtOMe2SiSiMe2OEt into aryl bromides RBr affording aryldimethylsilyl ethers RMe2SiOEt and Me2SiBrOEt in high yields.750 Williams and Tanaka et al. have reported on the palladium- and platinium-catalyzed reaction of carbonyl and imine compounds with disilanes.7... 

Palladium-catalysed C-C bond formation under Heck reaction conditions, which normally requires anhydrous conditions and the presence of copper(I) salts, is aided by the addition of quaternary ammonium salts. It has been shown that it is frequently possible to dispense with the copper catalyst and use standard two-phase reactions conditions [e.g. 18, 19]. Tetra-/i-butylammonium salts catalyse the palladium-catalysed reaction of iodoarenes with alkynes to yield the arylethynes in high yield [20, 21], whereas the reaction with 3-methylbut-1 -yn-3-ol (Scheme 6.30) provides a route to diarylethynes [22]. Diarylethynes are also formed from the reaction of an iodoarene with trimethylsilylethyne [23], Iodoalkynes react with a,p-unsaturated ketones and esters to produce the conjugated yne-eneones [19],... 

As an alternative to the Ullmann reaction, haloarenes are coupled to form the biaryls using palladium acetate in the presence of abase and tetra-n-butylammonium bromide [24], Yields are generally high (>70%) but dehalogenation of the haloarene may also occur as a side reaction. 

P-Phenylation of a,p-unsaturated ketones in high yield (75-85%), using the palladium catalysed reaction with phenylmercury(II) chloride or tetraphenyltin(IV), is promoted by tetra-n-butylammonium chloride [37],... 

Palladium clusters [51], solubilized by tetra-n-alkylammonium salts, are effective in the Suzuki coupling of phenylborinic acid with bromoarenes to produce biaryls... 

When sodium ethoxide is used in place of sodium hydroxide in the carbonylation reaction of benzyl halides with dicobalt octacarbonyl, ethyl esters are produced instead of the acids [15], Esters are also produced directly from iodoalkanes through their reaction with molybdenum hexacarbonyl in the presence of tetra-/i-butylammo-nium fluoride [16]. Di-iodoalkanes produce lactones [16]. The reaction can be made catalytic in the hexacarbonyl by the addition of methyl formate [16]. t-Butyl arylacetic esters are produced in moderate yield (40-60%) under phase-transfer catalytic conditions in the palladium promoted carbonylation reaction with benzyl chlorides [17]. 

The metal-catalysed autoxidation of alkenes to produce ketones (Wacker reaction) is promoted by the presence of quaternary ammonium salts [14]. For example, using copper(II) chloride and palladium(II) chloride in benzene in the presence of cetyltrimethylammonium bromide, 1-decene is converted into 2-decanone (73%), 1,7-octadiene into 2,7-octadione (77%) and vinylcyclohexane into cyclo-hexylethanone (22%). Benzyltriethylammonium chloride and tetra-n-butylammo-nium hydrogen sulphate are ineffective catalysts. It has been suggested that the process is not micellar, although the catalysts have the characteristics of those which produce micelles. The Wacker reaction is also catalysed by rhodium and ruthenium salts in the presence of a quaternary ammonium salt. Generally, however, the yields are lower than those obtained using the palladium catalyst and, frequently, several oxidation products are obtained from each reaction [15]. 

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