Carbonylative Cross Coupling
Carbonylative cross coupling reaction utilizes the ability of carbon monoxide to insert carbon-metal bonds to produce esters, amides, ketones, alcohols, and other products by the simultaneous introduction of a carbonyl group. It is a very efficient reaction in organic synthesis. It is often used in palladium-catalyzed coupling reactions.
We know that carbon monoxide is easily inserted between carbon-metal bonds. With a palladium catalyst, the reaction of an alkyl halide, carbon monoxide, and an alcohol together produces an ester. Replacing one of the alcohols with an amine gives an amide, replacing the alcohol with a hydrogen source gives an aldehyde, and switching to an organometallic reagent gives a ketone.
Examples of preparation of carboxylic acids and their derivatives by intercalation reaction
Preparation of aldehydes by the carbocation reaction
Carbonyl insertion! Selective synthesis of aldehydes and acids
Saegusa oxidation reaction
In 1978, T. Saegusa’s group reported the reaction of silyl enol ethers with stoichiometric Pd(OAc)2 and p-benzoquinone in acetonitrile at room temperature to give the corresponding α,β-carbonyl compounds. The conversion of the ketones to the corresponding enolylsilanes and the palladium-catalyzed regioselective oxidation to α,β-unsaturated ketones is referred to as the Saegusa oxidation reaction.
Wacker oxidation reaction
The palladium and copper chloride-catalyzed oxidation of an olefin to give a ketone and, in a few cases, an aldehyde.Image
Fukuyama coupling reaction
A reaction in which a ketone is obtained by coupling an organozinc compound with a thioate over a palladium catalyst. This reaction was discovered by Tohru Fukuyama in 1998 [Tetrahedron Letters. 39 (20): 3189-3192] and is the latest discovery of the classical palladium-catalyzed coupling reaction. This reaction is highly chemoselective, with mild reaction conditions and low toxicity of the reagents used. Due to the low reactivity of the organozinc reagent, the reaction has a good functional group tolerance, and ketones, esters, thioethers, aryl bromides, aryl chlorides and aldehydes can be stabilized under these reaction conditions.
Fukuyama reduction reaction
Pd/C-catalyzed reduction of thioesters to aldehydes using triethylsilane.
Fujiwara-Moritani Reaction
A direct olefinization coupling reaction of unmodified benzene rings in the presence of a Pd catalyst. Also an example of catalytic C-H activation. The form of the reaction is essentially comparable to the Heck reaction.
Example of palladium-catalyzed Hiyama coupling reaction, Hiyama Cross Coupling
A palladium-catalyzed cross-coupling reaction between an organosilicon reagent and an organohalogen or trifluoromethanesulfonate. An activating reagent in the form of a fluoride (TASF, TBAF) or a base (e.g., sodium hydroxide, sodium carbonate) is often added to the reaction, which would otherwise be difficult to carry out. The catalytic cycle is similar to the Kumada coupling.
The substituent on the silicon must usually be a heteroatom or a phenyl group. If it is a trialkylmethylsilane, it is difficult to form a silicate intermediate, so the coupling reaction is more difficult to carry out. Silicon has the advantage of low toxicity and is a promising reaction.
