Palladium dimethylsulfoxide

Palladium Paraformaldehyde Paraldehyde Pentaborane-9 Pentacarbonyliron Arsenic, carbon, ozonides, sulfur, sodium tetrahydridoborate Liquid oxygen Alkalies, HCN, iodides, nitric acid, oxidizers Dimethylsulfoxide Acetic acid, nitric oxide, transition metal halides, water, zinc... 

Iodides of soft metal ions such as mercury (II) are essentially un-ionized in dimethylsulfoxide 54). This feature is due both to the strength of the Hg-I bond and the weakness of the Hg-DMSO bond which appears to occur through the sulfur atom of the DMSO molecule, as is known for the palladium (II) complex 5S). 

Xlld does not involve the chiral center, so if the reaction takes place by this pathway, the migration of the alkyl group from sulfur to palladium (with the concomitant or subsequent loss of sulfur dioxide) must take place with inversion of configuration at carbon. Inversion of configuration at carbon has been observed in the reverse-type reaction, the sulfur dioxide insertion into a carbon-iron sigma bond (49). Nucleophilic displacement at carbon in compounds of type Xld is unusually difficult, so the reaction via the sulfite intermediate Xlld would appear to be more likely. Conversion of the tosylate of l-phenyl-2,2,2-trifluoroethanol to the corresponding chloride, a reaction which takes place in the presence of tetra- (n-butyl) ajnmonium chloride with inversion of configuration at carbon, requires 100°C for 24 hrs in dimethylsulfoxide. 

DEHYDROGENATION Dimethyl bromoma-lonate. Dimethylsulfoxide-Iodine. Pallad-ium(II) acetate. Palladium black. p-Tolu-enesulfmyl chloride. 

The solvent may determine the stereochemistry in the stoichiometric formation of 7r-allyl-palladium complexes from allyl halides. Strong donor solvents such as acetonitrile and dimethylsulfoxide lead to the expected m-ir-allyl complexes cis-16, whereas benzene, dichloro-methane or tetrahydrofuran give the. vva-addition product Irans-1639. Using soft carbanions in tetrahydrofuran. both complexes are converted to the corresponding alkylated products 17 with clean inversion of configuration. 

A one-pot sequential and cascade sequence involving the formation of allylic azides, from aryl/heteroaryl/vinyl halides, allene and sodium azide, by palladium catalyzed anion capture, and cyclization-anion capture, followed by 1,3-dipolar cycloaddition provided a variety of 1,2,3-triazoles in good yields <01T7729>. Reaction of a,P-acetylenic aldehydes 107 with sodium azide in dimethylsulfoxide followed by hydrolysis afforded 5-substituted-4-carbaldehyde-1,2,3-triazole derivatives 108 <01TL9117>. 

Hence, the majority of Mizoroki-Heck reactions show a clear preference for polar media, which lends assistance to both deligation of halide and support of the palladium catalyst (1) highly Lewis basic organic solvents such as DMF, DMA, iV-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO) (2) aqueous solvents (3) ionic liquids. 

Palladium chloride supported on silica gel and "y-alumina are active for the dimerization of ethylene [252]. PdCl2(Me2SO)2 and K PdCl,(MeSO) on KSH-2 silica gel catalyze ethylene dimerization. The yield of dimer and selectivity are high with use of 0.1% dimethylsulfoxide complex precipitated from acetone at 90°C and with 0.3% ionic complex precipitated from chlorobenzene at 100°C [252-255]. 

General procedure for the Heck reaction/anion-trapping cascade. The palladium catalyst (0.025 equiv), the ligand (0.05 equiv), and NaBr (2 equiv) were added to a solution of triflate (1 equiv) in dimethylsulfoxide (DMSO) (3.6mL/mmol). The mixture was degassed, and the sodium enolate of diethyl (2-((rerr-butyldiphenylsilyl)oxy)ethyl)malonate (0.33 M solution in DMSO, 2 equiv) was added dropwise at room temperature. After the appropriate reaction time, the mixture was cooled, extracted with Et20, and washed with 1-N aqueous HCl and brine. The organic extracts were dried and concentrated. Then, the residue was purified by flash chromatography on silica gel. 

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