Dichloro palladium

Palladium Dichloro-( j4-hexamethyl-bicyclo[2.2.0]hexa-2,5-dien)-E17f, 926 (Komplex-Synth.)... 

The structures of the palladium dichloro compounds 4 a-c were determined by single-crystal X-ray analysis. Compounds 4a,c show disorder which could be resolved salisfaclorily. The expected bidentate coordination of the diimine nitrogen atoms to the Pd(II) center, forming square-planar (Fig. 2.6, 4a,b) and distorted square-planar (Fig. 2.6, 4 c) coordination environments, is found for all three complexes (Tab. 2.1). 

The palladium chloride process for oxidizing olefins to aldehydes in aqueous solution (Wacker process) apparendy involves an intermediate anionic complex such as dichloro(ethylene)hydroxopalladate(II) or else a neutral aqua complex PdCl2 (CH2=CH2)(H2 0). The coordinated PdCl2 is reduced to Pd during the olefin oxidation and is reoxidized by the cupric—cuprous chloride couple, which in turn is reoxidized by oxygen, and the net reaction for any olefin (RCH=CH2) is then... 

The more halogens on a single carbon, the greater the ease of hydrogenol ysis, a fact that makes stepwise dehydrohalogenation an easy process, since each loss increases the resistance to further loss (4,13,21,24,29,71). Reduction of the dichloro compound 17 over palladium black gave 18 in 98% yield (8). 

To a mixture of vinyl bromide (40 mmol) and the catalyst dichloro-[(R)-Af,N-dimethyl-l-[(.S)-2-(diphenylphosphino)ferrocenyl]ethylamine]-palladium(n) (0.2 mmol) was added an ethereal solution of [a-(trimethyl-silyl)benzyl]magnesium bromide (0.6-1 m, 80 mmol) at —78 °C. The mixture was stirred at 30 °C for 4 days, and then cooled to 0 °C and hydrolysed with dilute aqueous HC1 (3 m). The organic layer was separated, and the aqueous layer was re-extracted with ether. The combined organic extracts were washed with saturated sodium hydrogen carbonate solution and water, and dried. Concentration and distillation gave the chiral allylsilane (79%, 66% ee), b.p. 55°C/0.4mmHg. 

Synthesis of isomeric chiral protected (63 )-6-amino-hexahydro-2,7-dioxopyrazolo[l,2- ]pyrazole-l-carboxylic acid 280 is shown in Scheme 36. Crude vinyl phosphonate 275, obtained by treatment of diethyl allyloxycarbonylmethyl-phosphonate with acetic anhydride and tetramethyl diaminomethane as a formaldehyde equivalent, was used in the Michael addition to chiral 4-(f-butoxycarbonylamino)pyrazolidin-3-one 272. The Michael addition is run in dichloro-methane followed by addition of f-butyl oxalyl chloride and 2 equiv of Huning s base in the same pot to provide 276 in 58% yield. The allyl ester is deprotected using palladium catalysis to give the corresponding acid 277, which is... 

Palladium-catalyzed bis-silylation of methyl vinyl ketone proceeds in a 1,4-fashion, leading to the formation of a silyl enol ether (Equation (47)).121 1,4-Bis-silylation of a wide variety of enones bearing /3-substituents has become possible by the use of unsymmetrical disilanes, such as 1,1-dichloro-l-phenyltrimethyldisilane and 1,1,1-trichloro-trimethyldisilane (Scheme 28).129 The trimethylsilyl enol ethers obtained by the 1,4-bis-silylation are treated with methyllithium, generating lithium enolates, which in turn are reacted with electrophiles. The a-substituted-/3-silyl ketones, thus obtained, are subjected to Tamao oxidation conditions, leading to the formation of /3-hydroxy ketones. This 1,4-bis-silylation reaction has been extended to the asymmetric synthesis of optically active /3-hydroxy ketones (Scheme 29).130 The key to the success of the asymmetric bis-silylation is to use BINAP as the chiral ligand on palladium. Enantiomeric excesses ranging from 74% to 92% have been attained in the 1,4-bis-silylation. 

The enantioselective hydrosilylation catalyst system based on the chiral pre-catalyst dichloro l- (/ )-l- [(S)-2 (dipheaylphosphinoKP) ferrocenyl] ethyl -3- trimethyl- phenyl-5-1 H- pyrazole-tc/V) palladium, 1 (shown in Figure 2) exhibits a interesting inversion of selectivity with a series of para-... 

The relevance of the palladium-catalyzed amidocarbonylation for natural product synthesis has been demonstrated with the multi gram-scale preparation of the central amino acid of chloropeptin I ((S)-3,5-dichloro-4-hydroxyphenylglycine) as well as methionine and p-chlorophenyl alanine via the combination of amidocarbonylation and enzymatic hydrolysis (Table 4) [44]. 

Palladium(ll) bis(benzonitrile)dichloride Palladium, bis(benzonitrile)dichloro-(8,9) (14220-64-5)... 

In an extensive study of the isomerization of hexenes and heptenes by platinum, palladium, and ruthenium, Harrod and Chalk (65) found that in many cases the equilibrium mixture of isomerized olefins was obtained. Isomerizations were achieved with Pt(II) (as 1,3-bisethylene-2,4-dichloro-fi-dichlorodiplatinum(II) with alcohol as cocatalyst), Pd(II)... 

Other dehydrogenation agents include sulfur, selenium dioxide, palladium on charcoal, and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). Some reactions proceed spontaneously. Dehydrogenation also occurred... 

Bis(diphenylphosphino)ferrocene]dichloropalladium Palladium, [1,1-bis(diphenylphosphino)ferrocene-P,P ]dichloro- (10) (72287-26-4) Bis(benzonitrile)dichloropalladium(ll) Palladium, bis(benzonitrile)dichloro- (8, 9) (14220-64-5)... 

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