Palladium-catalyzed hydroesterification of alkynes in the presence of p-toluenesulfonic acid under a normal pressure of carbon monoxide

Carbonylation of Alkynes, Alkenes and Alcohols using Metal Complex Catalysts

“…This Pd-H signal was found to be different from that observed for a mixture of Pd(PPh 3 ) 4 with excess TsOH in CDCl 3 , which showed two Pd-H signals at )6.7 and )7.3 ppm, corresponding to [HPd(PPh 3 ) 2 S] + (TsO ) ) and [HPd(P Ph 3 ) 3 ] + (TsO -), respectively, where S is a solvent molecule. The in situ formation of palladium hydride species from a mixture of Pd(0) complexes and acidic promoters has also been reported earlier [27], though no evidence of a specific complex (isolated) was reported. With these evidences, it has been proposed that the isolated palladium hydride complex has a formula [HPd(CO) (PPh 3 ) 2 ] + (TsO ) ).…”

“…This process required high temperatures in the range of 323-598 K and a very high operating pressure ranging from 30 to 300 MPa. However, with the proper choice of solvents using the same catalyst system, linear carboxylic acids and esters with high yields were reported by Knifton [15] which gave the linear isomer predominantly (65-85%) under comparatively lower CO pressures (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). Other low temperature processes were reported by Reis and co-workers [16] (operating at high pressures $30-70 MPa, 313 K), and Tsuji et al [17,18] (in an alcoholic solution of HCl in the presence of PdCl 2 ) for carbonylation of olefins.…”

“…Though this route has been replaced by other competitive routes for acrylic acid, it can be highly promising for synthesis of other derivatives consisting of unsaturated carboxylic acids. However, palladium based catalyst systems such as Pd(PPh 3 ) 4 , Pd(OAc) 2 / dppf, [55] Pd(OAc) 2 /PPh 3 /dppb, [56] Pd(dba) 2 /4PPh 3 [57] have been demonstrated to catalyse the carbonylation of alkynes at lower CO pressures (0.1-2 MPa), with significantly lower activity as the main drawback. Recently, a highly efficient catalyst for the carbonylation of alkynes has been reported by Drent et al, [58] in which palladium (II) catalysts along with 2-pyridylphosphine ligand and acidic promoters were used at 6 MPa of CO and 333 K. Carbonylation of propyne to methylmethacrylate, MMA was demonstrated using this catalyst to give a very high activity (Turnover frequency, TOF $40,000 h )1 ) and selectivity of 98.9-99.9%, thereby allowing a cost-effective single step process for MMA [59].…”

Catalytic Markovnikov and anti‐Markovnikov Functionalization of Alkenes and Alkynes: Recent Developments and Trends

“…Similar results for the hydroesterification of alkynes in butanol are obtained by using a catalyst system consisting of [Pd(dba) 2 ], 4 PPh 3 , pyridine carboxylic acid and p-toluenesulfonic acid. The resulting 2-substituted propenoic acid butyl esters are obtained in good selectivity and yield at 1 bar of CO. [100] Thus, for the hydroesterification of phenyl acetylene a maximum regioselectivity of 89 % towards the butyl ester of atropic acid is achieved. Not surprisingly the alkoxycarbonylation of alkynes in the presence of chiral alcohols gave chiral 2-arylpropenoic esters in good yields.…”

Pd-catalyzed carbonylation of α-arylvinyl bromides: Synthesis of 2-arylacrylic esters

“…This process employs three steps instead of the five in the original Boots process, with 100% atom-efficiency, where the key-step is the Pdcatalyzed carbonylation of 1-(p-isobutyphenyl)-ethanol [23]. On the other hand, Pd-catalyzed carbonylations of aryl acetylenes have been also used for the synthesis of 2-arylacrylic acids or esters [1][2][3][24][25][26][27][28][29]. These compounds are useful precursors for the enantioselective synthesis of 2-arylpropionic acids.…”