Catalytic Cross-Coupling Reaction of Esters with Organoboron Compounds and Decarbonylative Reduction of Esters with HCOONH₄:  A New Route to Acyl Transition Metal Complexes through the Cleavage of Acyl−Oxygen Bonds in Esters

Abstract

The Ru3(CO)12-catalyed cross-coupling reaction of esters with organoboron compounds leading to ketones is described. A wide variety of functional groups can be tolerated under the reaction conditions. Aromatic boronates function as a coupling partner to give aryl ketones. Acyl-alkyl coupling to dialkyl ketones is also achieved by the use of 9-alkyl-9-BBN in place of boronates. The Ru3(CO)12-catalyzed decarbonylative reduction of esters with ammonium formate (HCOONH4) leading to hydrocarbons is also described. No expected aldehydes are produced, and controlled experiments indicate that aldehydes are not intermediate for the transformation. A hydrosilane can also be used as a reducing reagent in place of HCOONH4. A wide variety of functional groups are compatible for both reactions. The key step for both catalytic reactions is the directing group-promoted cleavage of an acyl carbon-oxygen bond in esters, leading to the generation of acyl transition metal alkoxo complexes.

Synergistic Visible-Light Photoredox/Nickel-Catalyzed Synthesis of Aliphatic Ketones via N–C Cleavage of Imides

“…1 Among transition-metal-catalyzed acylation strategies, Suzuki coupling has become an increasingly essential protocol to forge acyl–carbon bonds. 2 Although the scope of the electrophilic partner in the acylative Suzuki coupling has been extended to different types of carboxylic acid derivatives, the use of acyl donors such as anhydrides, 3 active esters, 4 thiol esters, 5 and amides 6 is particularly attractive compared with acyl halides because these functional groups are generally more stable, nontoxic, and more widely available.…”

Catalyst-free alkanoylation of aromatic rings via arylstannanes. Scope and limitations

“…It should be mentioned that, in the last years, different strategies have been developed which could be applied to the synthesis of these bulky ketones, for example, F-C reactions catalyzed by In [10], BiCl 3 [11] or silica [12]; cross-coupling reactions with organoboron reagents [13]; the reaction of acyl chlorides and Grignard reagents catalyzed by metal halides [14] and the Pd-mediated crosscoupling of a-oxocarboxylic acids and aryl bromides [15]. The method here proposed enables the high regioselective formation of bulky ketones without employing a catalyst, that is, a more ecofriendly acylation of aromatic rings.…”

The Liebeskind–Srogl CC Cross‐Coupling Reaction

“…[50] Some of these methods for ketone synthesis require highly nucleophilic (strongly basic) organomagnesium and organolithium reagents and are therefore unsuitable for the synthesis of more complex multifunctional ketones, when a high degree of chemoselectivity is required. Alternative mild methods for ketone synthesis include the palladium-catalyzed coupling developed by Fukuyama and co-workers between thioesters and organozinc reagents [51] and related transition-metal-catalyzed transformations of boronic acids, such as palladium-catalyzed cross-coupling with carboxylic acids, [52,53] esters, [54] acid chlorides, [55,56] or anhydrides, [55][56][57] as well as the [Ru 3 (CO) 12 ]catalyzed cross-coupling of esters [58] with organoboron compounds.…”