Palladium benzyl methyl

This benzyl-methyl transfer reaction appears to be general in these systems. This process could involve the dehydrogenation of methanol on the surface of palladium, which produces formaldehyde. The formaldehyde could than add to the nitrogen atom to produce a quaternary carbinolamine (Scheme 4.92). 

The reaction of benzyl methyl carbonate with sodium benzenesulflnate and different palladium catalysts has shown that the best yields were obtained when a Pd( 3-C3H5)Cl2 - (DPEphos) catalyst was used in DMSO at 80 °C.121 Most of the reactions gave >90% yields of the benzyl aryl sulfone. In the suggested mechanism, the methyl carbonate leaving group is displaced by the catalyst, forming an (j 3-benzyl)palladium intermediate that reacts with the sodium salt of the arenesulfinate. 

Addition of several organomercury compounds (methyl, aryl, and benzyl) to conjugated dienes in the presence of Pd(II) salts generates the ir-allylpalladium complex 422, which is subjected to further transformations. A secondary amine reacts to give the tertiary allylic amine 423 in a modest yield along with diene 424 and reduced product 425[382,383]. Even the unconjugated diene 426 is converted into the 7r-allyllic palladium complex 427 by the reaction of PhHgCI via the elimination and reverse readdition of H—Pd—Cl[383]. 

To a solution of 180 parts of -benzyl N-benzyloxycarbonyl-L-aspartvI-L-phenylalanine methyl ester in 3,000 parts by volume of 75% acetic acid is added 18 parts of palladium black metal catalyst, and the resulting mixture is shaken with hydrogen at atmospheric pressure and room temperature for about 12 hours. The catalyst is removed by filtration, and the solvent is distilled under reduced pressure to afford a solid residue, which is purified by re-crystallization from aqueous ethanol to yield L-aspartyl-L-phenylalanine methyl ester. It displays a double melting point at about 190°C and 245°-247°C. 

Treatment of the ethyne derivative 71 with palladium chloride and mercuric chloride in the presence of carbon monoxide at a pressure of 1 atmosphere1131 gave methyl 2-(2,3,5-tri-0-benzyl-/3-D-ribofuran-osyl)maleate113c in high yield. This product may be considered to be a useful precursor to showdomycin. 

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]. 

In order to obtain a commercially viable process it is necessary to racemize the unwanted amine enantiomer, preferably in situ in a so-called DKR. The paUadium-on-charcoal-catalyzed racemization of amines was first reported by Murahashi et al. [23] and was later combined with Upase-catalyzed acylation, to afford a DKR, by Reetz [24] and others [25]. We were able to achieve a DKR of a-methyl benzyl-amine by performing the hpase-catalyzed acylation in the presence of a palladium nanoparticle catalyst (Scheme 6.10). 

The second way differs little from the previous, and consists of the initial formation of 4-hydroxy-3-acetoxybromoacetophenone (11.1.27) by acylation of methyl ester salicylic acid using bromoacetyl chloride. This is also reacted with iV-benzyl-tcrt-buty-lamine, and the resulting product (11.1.28) is completely hydrolyzed by lithium aluminum hydride into the (V-benzyl substituted albuterol (11.1.29), the benzyl group of which is removed by hydrogen over a palladium catalyst to give the desired albuterol (11.1.26) [31]. 

Labetalol Labetalol, 2-hydroxy-5-[l-hydroxy-2-[(l-methyl-3-phenylpropanol)amino)] ethyl] benzamide (12.1.12) is synthesized by the WaUcylation of iV-benzyl-Af(4-phenyl-2-butyl)amine 5-bromacetylsalicylamide and forming aminoketone (12.1.11), which is further debenzylated by hydrogen using a palladium-platinum on carbon catalyst into labetalol (12.1.12) [28-30]. 

The annelation of benzo rings on pyridazines was covered in CHEC-II(1996) <1996CHEC-II(6)1>. Maes and Matyus reported new examples in their synthesis of the dibenzo[// ]phthalazin-l(27r)-one and dibenzo[//]cinnolin-3(27/)-one skeleton. Palladium-catalyzed intramolecular arylation of 2-benzyl-5-(2-bromophenyl)-4-phenylpyridazin-3(2//)-one yielded 2-benzyldibenzo[/,4]phthalazin-l(2//)-one. The synthesis of this new tetracyclic pyridazinone from 2-benzyl-5-(2-aminophenyl) -phenylpyridazin-3(2//)-one via a Pschorr-type reaction was also investigated. Similarly, the con-stmction of 2-methyldibenzo[/, ]cinnolin-3(2//)-one from 2-methyl-5-(2-bromophenyl)-6-phenylpyridazin-3(27T)-one and 2-methyl-5-(2-aminophenyl)-6-phenyl-pyridazin-3(2//)-one was performed <2003T5919>. 

The same product was obtained when 4-chloro-5-methyl-2-(methylthio)pyrimidine 236 was reacted with benzyl-zinc bromide, due to selective palladium-catalyzed displacement of the 2-methylthio group, followed by nucleophilic displacement of the 4-chloro substituent of the intermediate 237 by the liberated zinc thiomethoxide <2000SL905>. 

Finally, new palladium(II) and platinum(II) complexes from 4-benzyl-4-methyl-2-phenyl-5(477)-oxazolone or C2 symmetric bis(oxazolone) ligands have been... 

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