Preparation and Reactivities of Acyl(carboxylato)palladium Complexes

Abstract

Acyclic acid anhydrides oxidatively add to Pd(styrene)(PMe3)2 with C-O bond cleavage to give corresponding acyl(carboxylato)palladium(II) complexes 3a-3e that are isolated and identified. The acetato ligand in 3a is exchanged with added acetic acid. Treatment of 3a with formic acid at room temperature yields acetaldehyde, acetic acid and CO2. Reaction of 3a with dihydrogen liberates acetaldehyde, acetic acid and ethanol. Catalytic hydrogenolysis of octanoic and benzoic anhydrides into aldehydes and carboxylic acids was found to be catalyzed by Pd(PPh3)4.

Low‐Pressure Hydrogenation of Arenecarboxylic Acids to Aryl Aldehydes

“…A new concept for the direct reduction of carboxylic acids to aldehydes was introduced by Yamamoto et al [6] In his single-step protocol the carboxylic acids are activated in situ by treatment with pivalic anhydride. The resulting equilibrium mixture of anhydrides undergoes a palladium-catalyzed hydrogenation to give the aldehydes along with pivalic acid (Scheme 1).…”

Acid anhydrides as alternatives to acid chlorides in the palladium‐catalyzed reaction with silacyclobutanes

“…Reactions of 2 with other acid anhydrides, p-toluic anhydride (1b), p-anisic anhydride (1c), p-fluorobenzoic anhydride (1d), and cinnamic anhydride (1e) under the same conditions provided similar products 3b±e along with small amounts of 4b±e respectively. Compounds 3b±e and 4b±e showed satisfactory 1 …”

Rate and Mechanism of the Oxidative Addition of Benzoic Anhydride to Palladium(0) Complexes in DMF

“…The oxidative addition of carboxylic anhydrides to palladium(0) complexes has been reported by Yamamoto et al [6Ϫ8] It proceeds by cleavage of one CϪO bond and trans-acyl(carboxylato)palladium(II) complexes have been isolated and characterized with the PMe 3 ligand [Equation (3), (R ϭ alkyl or phenyl)]. [6,7] (3)…”

“…Hydrogenation gives RCHO and RCO 2 H, establishing that no decarbonylation occurs in the acyl(carboxylato)palladium(II) complex formed in the oxidative addition. [6,7] Hydrogenation of (PhCO) 2 O to form PhCHO and PhCO 2 H has been successfully developed in THF with [Pd 0 (PPh 3 ) 4 ] as a catalyst. [6Ϫ8] Only one reaction in the aromatic series is reported (phthalic anhydride, PMe 3 as the ligand), where CO is released from the acyl(carboxylato)-palladium(II) complex, giving rise to the formation of an aryl(carboxylato)Pd II complex.…”

“…[6Ϫ8] Only one reaction in the aromatic series is reported (phthalic anhydride, PMe 3 as the ligand), where CO is released from the acyl(carboxylato)-palladium(II) complex, giving rise to the formation of an aryl(carboxylato)Pd II complex. [7] Grushin and Alper have characterized in solution the complex trans-[(PhCO)Pd(OCOPh)(PCy 3 ) 2 ] formed by reacting (PhCO) 2 O with [Pd 0 (PCy 3 ) 2 ] (Cy ϭ cyclohexyl). [9] Decarbonylation was observed in the course of the oxidative addition as a very minor process (5Ϫ10%).…”