Palladium‐Catalyzed Carbonylation of Chloroacetates to Afford Malonates: Controlling the Selectivity of the Product in a Buffer

Abstract

We report an efficient process for the synthesis of diethyl malonate (DEM) and other malonates through the palladium‐catalyzed carbonylation of chloroacetates. Excellent selectivity (96 %) and yield (94 %) were obtained without the formation of Pd black. For the first time, a weakly alkaline buffer was used to control the selectivity for DEM in the reaction and we discuss the relationship between the buffer medium and selectivity in the reaction. The combination of anisole as the solvent and a Na2HPO4/NaH2PO4 buffer was beneficial for completely restraining the phase‐transfer‐catalyzed substitution of DEM with ethyl chloroacetate, as well as accommodating the proposed [(PPh3)2PdI]−[Bu4N]+ intermediate, by providing a suitable environment for its stable existence. We achieved the highest efficiency in the catalytic cycle by fine‐tuning the balance between the rates of oxidative addition and reductive elimination; moreover, we synthesized a recoverable heterogeneous polymer‐bound Pd catalyst in 85 % yield that could be reused without an appreciable loss in activity over four cycles.

Carbonylative Suzuki coupling and alkoxycarbonylation of aryl halides using palladium supported on phosphorus‐doped porous organic polymer as an active and robust catalyst

“…These results were also consistent with the observed experimental phenomena that the recovered catalyst kept a light brown colour during the recycling (Figure S3). The above results were different from the general immobilized palladium complexes, in which palladium species were usually partially reduced to palladium nanoparticles during the carbonylation reaction . Considering the structure of the catalyst, the good performance could be attributed to the high ligand concentration and excellent porous structure.…”

Palladium Nanoparticles Supported on Triphenylphosphine-Functionalized Porous Polymer as an Active and Recyclable Catalyst for the Carbonylation of Chloroacetates

“…However, the presence of excess Me 4 NI afforded a little lower yield of diethyl malonate (entry 11). When the reaction time was further prolonged to 9 h, a high yield (94.9%) of diethyl malonate was obtained (entry 12), which was a little bit higher than that of a previously reported homogeneous and colloid catalyst [39,40]. Under the optimal conditions, we tried to lower the CO pressure, while a slight decrease in yield was observed (entry 13).…”

“…With the catalyst in hand, we started our investigation with the carbonylation of ethyl chloroacetate (ECA) as a model reaction. Previous results [39,40] showed that the solvent and base have great impacts on the activity and selectivity of this carbonylation reaction. Hence, the effect of solvent and base was first investigated.…”

“…5 Pd(PPh 3 ) 2 Cl 2 (14 mg, 0.02 mmol). Previous research [39,40] suggested that the iodide promoter could extensively enhance the catalytic activity of this reaction. Therefore, the effect of a promoter was investigated ( Table 3).…”

“…Dialkyl malonates are important organic intermediates that are widely used as building blocks for the synthesis of vitamins, pharmaceuticals, agrochemicals, and so on [39]. To continue our ongoing efforts for exploring efficient catalysts for the synthesis of dialkyl malonate [40], herein, we reported palladium nanoparticles supported on a triphenylphosphine-functionalized porous polymer (PdNPs@POP-Ph 3 P) as an active and recyclable catalyst for the carbonylation of chloroacetates.…”