Palladium‐Catalyzed Hydroformylation of Alkenes and Alkynes

Abstract

Dedicated to Prof. Eite Drent for his contributions to the field of Pd-catalyzed hydrocarbonylation chemistryHydroformylation of alkenes and alkynes with syngas represents a method of choice to furnish valuable aldehydes with the 100 % atom-economy from readily available building blocks. The field is dominated by Rh-and Co-catalysis; however, complexes of many other metals were also shown to be catalytically competent. Here we review the studies of hydroformylation under Pd-catalysis, starting from the seminal reports up to the most recent examples. Special emphasis is paid to the unique regio-and chemoselectivities of Pd-based methods, which are difficult to achieve with the conventional hydroformylation protocols. Different mechanistic proposals are presented along with a summary of their experimental and computational support. Finally, the user-friendly methods using surrogates of syngas are discussed as well. Overall, the Minireview aims to present unique opportunities and remaining challenges of Pd-catalyzed hydroformylation reactions for their prospective applications in fine-chemical synthesis.

Recent advances in Cu-catalyzed carbonylation with CO

“…As one of the most important homogeneously catalyzed industrial processes, hydroformylation 50 has been widely studied by using Rh, 51 Ru, 52 Pd, 53 Co 54 etc. However, copper-catalyzed hydroformylation has not been reported.…”

Isoselective Hydroformylation of Propylene by Iodide‐Assisted Palladium Catalysis

“…We hypothesized that Pd catalysis would be attractive for isoselective hydroformylation of propylene. With the exception of three n‐selective catalysts, [25–27] Pd complexes are typically poorly active in hydroformylation [28, 29] . However, in our recent mechanistic studies of Pd‐catalyzed hydroformylation of functionalized alkenes, [30] we discovered that iodide can act as an active ligand, working with phosphines to form the aldehyde products.…”

“…The aldehydes might be released from the Pd-acyl C intermediates upon reacting with either dihydrogen following the mononuclear mechanism or another molecule of the Pd hydride species A following the binuclear mechanism. [28] We favor the binuclear mechanism for this iodide-dependent catalytic system because the previous mechanistic studies indicated that the iodide anions promote the binuclear over the mononuclear mechanism; [30] however further studies are required to underpin the exact mechanism.…”

“…With the exception of three n-selective catalysts, [25][26][27] Pd complexes are typically poorly active in hydroformylation. [28,29] However, in our recent mechanistic studies of Pd-catalyzed hydroformylation of functionalized alkenes, [30] we discovered that iodide can act as an active ligand, working with phosphines to form the aldehyde products. Such a phosphine-iodide cooperativity can substantially increase the activity of Pd complexes.…”

Partial reductions of carboxylic acids and their derivatives to aldehydes

“…5 Therefore, exhaustive efforts have been devoted to the development of efficient and selective synthesis of aldehydes, both academically and industrially. [6][7][8][9] Most commonly, aldehydes can be accessed by hydroformylations of alkenes with syngas (also referred to as synthesis gas, a mixture of CO and H 2 ) in the presence of well developed catalytic systems, [6][7][8][9] and by well controlled partial oxidations of primary alcohols 5,[10][11][12] with a number of elegantly designed reliable oxidizing reagents or catalysts. Besides, carboxylic acid or its derivatives are also ideal substrates for synthesizing aldehydes due to their rich abundance and structural diversity.…”