Palladium tetrakis-triphenylphosphine reaction with

More recently, substituted allenyl sulfones were also engaged in Pd/Ag-catalyzed Heck-type reactions. Treated with palladium tetrakis(triphenylphosphine) and a mixture of silver and potassium carbonate in DMF at 80°C, such allenyl sulfones... 

Attention now turned to the installation of the carbonyl moiety. First, carbon-ylation of iodide 45 with bis(triphenylphosphine)palladium(II) dichloride and hydrazine at 60 °C was investigated (Entry 1, Table 4). After 30 min, the starting material had been fully consumed, furnishing a low yield of an unidentifiable product, and potentially formed via reaction of hydrazine with the carbonyl moiety. In contrast, application of high temperature carboalkoxylation conditions was successful (Entry 2). Carboalkoxylation with carbon monoxide catalyzed by palladium tetrakis(triphenylphosphine) with... 

Palladium-Catalyzed Coupling Reaction with Organo-halides. In the presence of tetrakis(triphenylphosphine)-palladium(O), vinyl halides (12) are converted to the corresponding vinylsilanes (13) with the aid of MegSi2 and tris-(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) in 53-92% yields with high chemoselectivity and stereospecificity (eq 6). Similarly, aryl-, benzyl-, and allylsilanes are obtained from the corresponding halides in 57-100, 8 8, and 52-93% yield, respectively. Allyl esters also are transformed by Pd-catalyzed reaction of Me6Si2 into allylsilanes. ... 

A synthetically useful virtue of enol triflates is that they are amenable to palladium-catalyzed carbon-carbon bond-forming reactions under mild conditions. When a solution of enol triflate 21 and tetrakis(triphenylphosphine)palladium(o) in benzene is treated with a mixture of terminal alkyne 17, n-propylamine, and cuprous iodide,17 intermediate 22 is formed in 76-84% yield. Although a partial hydrogenation of the alkyne in 22 could conceivably secure the formation of the cis C1-C2 olefin, a chemoselective hydrobora-tion/protonation sequence was found to be a much more reliable and suitable alternative. Thus, sequential hydroboration of the alkyne 22 with dicyclohexylborane, protonolysis, oxidative workup, and hydrolysis of the oxabicyclo[2.2.2]octyl ester protecting group gives dienic carboxylic acid 15 in a yield of 86% from 22. 

In 1988, Linstrumelle and Huynh used an all-palladium route to construct PAM 4 [21]. Reaction of 1,2-dibromobenzene with 2-methyl-3-butyn-2-ol in triethylamine at 60 °C afforded the monosubstituted product in 63 % yield along with 3% of the disubstituted material (Scheme 6). Alcohol 15 was then treated with aqueous sodium hydroxide and tetrakis(triphenylphosphine)palladium-copper(I) iodide catalysts under phase-transfer conditions, generating the terminal phenylacetylene in situ, which cyclotrimerized in 36% yield. Although there was no mention of the formation of higher cyclooligomers, it is likely that this reaction did produce these larger species, as is typically seen in Stephens-Castro coupling reactions [22]. 

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... 

One of the earliest syntheses of lavendamycin methyl ester, however, did not employ either the Pictet-Spengler or the Bischler-Napieralski reactions for construction of the /J-carboline ring system. Instead, a palladium-promoted ring closure of aryl pyridine 36 (Fig. 12) was used to prepare /1-carboline 37 by Boger and coworkers [35]. Unfortunately, stoichiometric palladium was found to be necessary, in this case 1.5 equivalents of the tetrakis(triphenylphosphine)palladium(0) being used. Friedlander condensation with aldehyde 38 in the presence of benzyltrimethylammonium hydrox-... 

Various intermolecular coupling reactions involving acetylene hydrocarbons have been reported to lead to vinylallenes. For example, 1-phenylpropyne (93), after activation with Hg(II) chloride, is first metalated by butyllithium treatment, then trans-metalated with zinc bromide and finally coupled with 1-iodo-l-phenylethene (94) in the presence of tetrakis(triphenylphosphine)palladium to provide the diphenylvinyl-allene 95 in moderate yield (Scheme 5.12) [31]. 

Substitution reactions of allylic nitro compounds often lead to rearranged products, as in palladium(0)-catalysed aminations and alkylations. Thus treatment of the nitro ester 419 with piperidine in the presence of tetrakis(triphenylphosphine)palladium yields a mixture of the unrearranged and rearranged amines 420 (R = piperidin-l-yl) and 421... 

The Csajagi research group used a commercial X-Cube continuous flow reactor system [32] to perform similar reactions. The reactor is made of stainless steel, capable of reaching pressures of up to 150 bar, and equipped with preloaded catalyst cartridges. Monoamides of aryldicarboxylic acids are obtained in a reaction over a tetrakis(triphenylphosphine)palladium catalyst using A-methylpyrrolidone as base [33]. Terephtalic acid was reported as the byproduct, but not the oc-ketoamide. 

Pyrrolo-benzoxazepine 402 (Scheme 84, Section 5.2.1.1) gives ester 403 through the triflate intermediate by reaction with carbon monoxide and methanol in the presence of tetrakis(triphenylphosphine)palladium (1996JMC3435). 

Trialkylstannyl groups can also be replaced by reactive electrophiles in certain cases, but most commonly stannylated azaheterocycles are employed in palladium catalyzed cross-coupling reactions [85PAC1771 86AG(E)508 92S413]. For example, trimethylstannylpyridines can be reacted with bromopyridines in the presence of catalytic amounts of tetrakis-(triphenylphosphine)palladium to give a variety of different bipyridines (Scheme 158)(86S564). 

Reaction with the trimethylsylil derivative of acetylene in the presence of tetrakis-triphenylphosphine palladium leads to the replacement of iodine by the acetylide. Tributylammonium fluoride then removes the silyl protecting group to afford the kinase inhibitor erlotinib (78-7) [87]. 

The oxidative addition is quite general with alkyl, allyl, benzyl, vinyl, and aryl halides as well as with acyl halides to afford the palladium (II) complex VII. The frans-bis( triphenylphosphine )alkylpalladium halides can also be carbonylated in an insertion reaction to give the corresponding acyl complexes, the stereochemistry of which (17, 18) proceeds with retention of configuration at the carbon bonded to palladium. The acyl complex also can be formed from the addition of the corresponding acid halide to tetrakis (triphenylphosphine) palladium (0). 

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