Palladium dichloride synthesis

Thoumazet C, Ricard L, Grutzmacher H, Le Floch P (2005) Dibenzo[a,d]cycloheptenyl dibenzophosphole palladium dichloride synthesis. X-ray-crystal structure and application in the Suzuki-Miyaura coupling. Chem Comm 1592... 

A similar approach was taken for the synthesis of 45 by Miyaura. " Shaughnessy and Booth synthesized the water-soluble alkylphosphine 46, and found it to provide very active palladium catalysts for the reaction of aryl bromides or chlorides with boronic acids. The more sterically demanding ligand 47 was shown to promote the reactions of aryl chlorides with better results than 46. Najera and co-workers recently reported on the synthesis of di(2-pyridyl)-methylamine-palladium dichloride complexes 48a and 48b, and their use in the coupling of a variety of electrophiles (aryl bromides or chlorides, allyl chlorides, acetates or carbonates) with alkyl- or arylboronic acids very low catalyst loadings at Palladium-oxime catalysts 8a and 8b) have also been developed. In conjunction with... 

A very few examples of the use of aryl-tin,21 -lead,21 -lithium43 and -magnesium21143,44 derivatives as the source of the aryl group in vinyl substitutions have been reported. Tin derivatives have been used with palladium dichloride bis(benzonitrile) and a copper(II) chloride reoxidant in a regioselective synthesis of oxygen heterocycles from unsaturated alcohols.43... 

Complex compounds with halide bridges are prepared by immediate interaction of unsaturated hydrocarbons with metal salts (Sec. 2.2.4.1). Their examples are classic 7i-complexes of the type 123 which are characteristic for fi 8-metals [75]. Such complexes are also formed by the method of ligand exchange. The bridges of this type are widespread in products of cyclometallation reactions with the use of metal halides (Sec. 2.2.5.1) 371-374, 381, 382 [41,46,48]. An example of such a synthesis is the reaction of arylhydrazones of 2-oxopropionic aldehyde and benzoylformalde-hyde, as well as butadiene-2,3-dione 635, with palladium dichloride, leading (3.71) to dipalladium complexes 636 [88] ... 

In the final phase of the synthesis, it was necessary to effect debenzylation and to isolate 95 in advance of exposing this vinyl iodide to 96 and the palladium dichloride bis(acetonitrile) complex in cold THE The synthetic polycavemoside A obtained in this maimer was identical in all respects to the natural material. 

Scheme 3.4 Synthesis of N,N- 2,3-bis(2,6-dibromophenylimine butane) palladium dichloride.

Ethynyl-2-nitrophenol (Attempted Alternate Synthesis). To a stirred solution of 4-iodo-2-nitrophenol (14.Og, 0.053 mole)(7) in 150 ml of tetrachloroethylene was added bis(triphenylphosphine) palladium dichloride (0.74g, 0.001 mole), cuprous iodide (0.40g, 0.002 mole), triphenyl phosphine (0.03g, 0.001 mole), and 50 ml of dry triethylamine. After the reactants were thoroughly mixed, 2-methyl-3-butyn-2-ol (5.4g, 0.064 mole) was added. The stirred reaction mixture was heated slowly to 70-75°C and maintained at that temperature for 16 hours. The tetrachloroethylene and triethylamine were removed under reduced pressure and the red gumlike residue was extracted with hot heptane. The heptane solution was treated with charcoal and the heptane was stripped off to give a yellow solid (9.5g). The solid was dissolved in benzene and was placed in a silica gel column. Elution with 1 1 benzene/hexane yielded 1.8g of product. The remainder of the product was removed... 

The precursor aryl-malonamide 21 is prepared in a three-step procedure from 2,6-diethyl-toluidine. A technically feasible cross<oupling reaction has been developed for the synthesis of aryl malononitrile 20 starting from benzene derivative 19 and malononitrile. The optimized procedure with PdQ2/tricyclo-hexylphosphine and sodium tert-butoxide as base in refluxing xylene [81] was improved even further using palladium dichloride/triphenylphosphine as catalyst and sodium hydroxide as base in l-methyl-2-pyrrolidone at 125-130 °C [82]. The aryl-malononitrile 20 is hydrolyzed to the aryl-malonamide 21 in cone, sulphuric acid. 

The second example involves the kinetic resolution of racemic secondary alcohols, a process that also has been used in a total synthesis. As illustrated in Figure 14.27, the naturally occurring tricyclic diamine sparteine, in combination with palladium dichloride and oxygen as the terminal oxidant, catalyzes the oxidation of one enantiomer of the race mic benzylic alcohol to the ketone faster than it oxidizes the other enantiomer. The desired unreacted alcohol was isolated in 47% yield with 99% ee (s > 47) and was subsequently transformed to (+)-amurensinine. ... 

Two isomeric acetylenic benzothiazole monomers, 2-(3-ethynyl-phenyl)-5-ethynylbenzothiazole (3) and 2-(3-ethynylphenyl)-6-ethynyl-benzothiazole (4) were prepared according to the general reaction scheme shown below. The synthesis of the benzothiazole heterocyclic structure was carried out by the condensation of m-bromobenzoic acid with isomeric bromo-substituted o-aminomercaptobenzenes in poly-phosphoric acid (PPA). The bis-bromobenzothiazoles were converted to the acetylene systems by the reaction with 2-methyl-3-but3m-2-ol and subsequent displacement of acetone with base. The bromo displacement reaction utilized a catalyst composed of triphenylphosphine, (bis-triphenylphosphine)palladium dichloride and cuprous iodide. 

In other experiments the formation of 1 1 adducts was observed. For instance, when the reaction of 2,3-dimethylbutadiene with methyl aceto-acetate is carried out in the presence of a catalyst composed of palladium dichloride and 3-methyl-1-phenyl-A -phospholene the 1 1 adduct 3-car-bomethoxy-5,6-dimethyl-5-hepten-2-one is formed (Equation 32). Alkali decomposition of this ketone gives 5,6-dimethyl-5-hepten-2-one, a key intermediate for the synthesis of a-irone [39]. 

Finally, an intramolecular cyclization of a bis-o-quinonemethide (32) was employed by Chapman in the total synthesis of the lignan carpanone (31). In this remarkably facile synthesis the required o-quinonemethide was generated situ by phenolic coupling of two molecules of 2-(trans-l-propenyl)-H,5 methylenedio henol (33) with palladium dichloride. This procedure led directly to carpanone (33.) in 46% yield and involves the introduction of five asymmetric centers in a single step. 

The applications of palladium-catalyzed allylation reactions in the realm of total synthesis have been numerous, owing to the general functional group tolerance and high stereoselectivity observed in these transformations [8,17, 25, 27, 30]. In pioneering studies, Trost reported that alkene 1 was converted into allylpalladium complex 2 on treatment with a stoichiometric amounts of palladium dichloride (Scheme 14.1) [42]. Nucleophilic substitu-... 

The Boekelheide reaction has been applied to the synthesis of non-natural products with the preparation of quaterpyridines serving as an example. The sequence began with the 2,4-linked bipyridyl-N-oxide 25. Execution under the typical reaction conditions produced the expected bis-pyridone 26. Treatment with POCI3 afforded the corresponding dichloride that was submitted to a palladium-catalyzed coupling with 2-stannyl pyridine to produce the desired quaterpyridine 27. 

Dialkylindolines and 1,3-dialkylindoles are formed in poor yield (<10%) from the reaction of ethyl- or phenymagnesium bromide with 2-chloro-N-methyl-N-allylaniline in the presence of catalytic quantities of (bistriphenylphosphine)nickel dichloride.72 In a modification of this procedure, the allyl derivatives can be converted by stoichiometric amounts of tetrakis(triphenylphosphine)nickel into 1,3-dialkylindoles in moderate yield72 (Scheme 43) an initial process of oxidative addition and ensuing cyclization of arylnickel intermediates is thought to occur. In contrast to the nickel system,72 it has proved possible to achieve the indole synthesis by means of catalytic quantities of palladium acetate.73 It is preferable to use... 

Reactions of Vinylthiophens and Related Compounds. - 2-Aroyl-5-vinyl-thiophens react with triphenylphosphine, palladium chloride, and carbon monoxide to give 2-(5-aroyl-2-thienyl)propionic acid. Cycloaddition of sulphene, from methanesulphonyl chloride and triethylamine, to 2-(a-dimethylaminovinyl)thiophen gave (160). The synthesis of some substituted 3-(2-thienyl)acryloylamino-acids has been described. Some reactions of 3-chloro-j8-(2-thienyl)vinylphosphonic acid dichlorides have been studied, ... 

Nitrogen Systems.—Monoaza-compounds. Treatment of the azapentalene anion (745) with dichloromethane and butyl-lithium yields a mixture of indolizine (746 R = H) and compound (747) it has been established that the latter is not a precursor of indolizine.3-Diethylaminoindolizine (746 R = NEt2) is formed by the reaction of 2-bromopyridine with propargyl alcohol and diethylamine in the presence of bis(triphenylphosphine)palladium(ll) dichloride and copper(i) iodide. The pyridinium ylide (748) undergoes 1,5-dipolar cyclization to the tran -dihydroindolizine (749). As in previous years, there have been several reports on the synthesis of the indolizine ring system from pyridinium ylides the methide (750 R = H, R = Ph) adds benzylideneacetophenone to form the tetrahydroindolizine (751), the action of phenyl vinyl sulphoxide. 

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