CO Surrogate Research Articles

Pd/C in Propylene Carbonate: A Sustainable Catalyst–Solvent System for the Carbonylative Suzuki–Miyaura Cross‐Coupling Using N‐Formylsaccharin as a CO Surrogate

This work documents the first Pd/C‐catalyzed carbonylative Suzuki–Miyaura cross‐coupling of aryl iodides with N‐formylsaccharin as a CO surrogate. In contrast to previous reaction protocols, which make use of toxic and hazardous solvents, the reaction could be advantageously performed in propylene carbonate as an environmentally benign and sustainable polar aprotic solvent. A range of biaryl ketones, including (4‐methoxyphenyl)(3,4,5‐trimethoxyphenyl)methanone, an antineoplastic belonging to the phenstatin family, could be synthesized under cocatalyst‐free, additive‐free and ligand‐free conditions. The Pd/C could be recycled up to five times under CO surrogacy with only a marginal decrease in catalytic activity. The reaction could also be scaled up to gram‐scale syntheses.

Palladium catalyzed aroylation of NH-sulfoximines with aryl halides using chloroform as the CO precursor

Abstract A palladium-catalyzed aroylation of NH-sulfoximines for the efficient synthesis of N -aroyl sulfoximines from aryl halides and chloroform has been developed. The mild reaction conditions (temperature, catalyst loading) and the use of a CO surrogate render this transformation a useful method for the synthesis of N -aroyl sulfoximines from available feedstock.

Carbonylations with CO2 as the CO Source and Reactivity Modifier.

A CO surrogate: In two recent studies, CO2 has not only been applied as a CO source in the hydroformylation of alkenes and the carbonylative Hiyama-Denmark coupling of aryl iodides, but more interestingly it also attenuates or improves the reactivity of the reactants.

Transition-Metal-Free β-C-H Bond Carbonylation of Enamides or Amides with a Trifluoromethyl Group as CO Surrogate for the Synthesis of 1,3-Oxazin-6-ones.

A cascade β-C-H bond trifluoromethylation/C(sp3)-F bond activation/hydrolysis reaction of enamides with Togni's reagent has been disclosed. This formal C-H bond carbonylation reaction utilizes the CF3 group as a CO surrogate to provide an efficient approach to 1,3-oxazin-6-ones in satisfactory yields. Furthermore, CF3-containing 1,3-oxazin-6-ones could also be accessed using this method by using alkenyl N-ethylamides involving the functionalization of one Csp2-H, one Csp3-H, one Csp2-H, and three Csp3-F bonds. The broad substrate scope of this method enables access to synthetically or pharmaceutically important compounds, which are difficult to access by known methods.

Pd/C catalyzed phenoxycarbonylation using N-formylsaccharin as a CO surrogate in propylene carbonate, a sustainable solvent

Recyclable and commercially available Pd/C catalyzes the phenoxycarbonylation reaction usingN-formylsaccharin as a CO surrogate in propylene carbonate as an environmentally benign and sustainable polar aprotic solvent under co-catalyst free, ligand free and additive free conditions.

Palladium-catalyzed carbonylative synthesis of isocoumarins and phthalides by using phenyl formate as a carbon monoxide source.

A simple and efficient palladium-catalyzed intramolecular carbonylative synthesis of isocoumarins and phthalides from the easily available starting materials by employing phenyl formate as a CO surrogate has been achieved. The approach affords target compounds in good to excellent yields with the advantages of lower toxicity, milder conditions, easy operation and wide functional group tolerance.

Regioselective Thiocarbonylation of Vinyl Arenes.

A palladium-catalyzed thiocarbonylation of styrene derivatives is reported for the first time. The combination of thiols as nucleophiles and a bidentate ligand ensures a unique reaction outcome with high regioselectivity toward the more valuable branched isomer and new reactivity. The ambient reaction conditions (temperature, catalyst loading) and the use of a CO surrogate render this transformation a useful method for the synthesis of thioesters from available feedstock. Various functional groups on arene and thiol substituents are tolerated by the system. Notably, challenging ortho-substituted styrenes are converted with unprecedentedly high regioselectivity.

One-Pot Synthesis of Carbamoyl Azides via Palladium-Catalysed Azidocarbonylation of Haloarenes Using N-Formylsaccharin as a CO Surrogate

A highly efficient one-pot synthesis of carbamoyl azides from haloarenes and sodium azide has been developed. The protocol involves palladium-catalysed azidocarbonylation of haloarenes utilizing N-formylsaccharin as a CO source to form acyl azides, which undergo in situ Curtius rearrangement to afford the desired carbamoyl azides. N-Formylsaccharin is an easy-to-handle solid alternative to CO gas.

Transition Metal-Catalyzed Carbonylative C-H Bond Functionalization of Arenes and C(sp(3))-H Bond of Alkanes.

In this article, we present the progress made in the area of carbonylative C-H functionalization, with special emphasis on arenes and alkanes. The importance of directing group assistance and C-H functionalization using CO surrogates is also included. The budding development in the area of transition metal-catalyzed C(sp(3))-H activation makes us feel it necessary to file a summary on the past, as well as current, contributions and a prospective outlook on the transition metal-catalyzed carbonylative transformation of C-H bonds, which is the focus of this review.

Practical Synthesis of Axially Chiral Dicarboxylates via Pd-Catalyzed External-CO-Free Carbonylation.

We have developed a safe and practical synthetic method for preparing axially chiral diphenyl dicarboxylates using Pd-catalyzed external-CO-free carbonylation with phenyl formate as a CO surrogate. Optimized conditions consisted of axially chiral [1,1'-binaphthalene]-2,2'-diyl ditriflate and its congeners, each easily prepared from commercially available enantiomerically pure diols, Pd(OAc)2, 1,3-bis(diphenylphosphino)propane, ethyldiisopropylamine, and no solvent. To demonstrate the potential utility of these products, this method was conducted on gram-scale and the phenyl ester products were converted to other useful compounds, and both processes were carried out without difficulty.

An easy access to carboxylic acids via Pd-catalyzed hydrocarboxylation of olefins with HCOOLi as a CO surrogate under mild conditions

This paper describes an easy access to carboxylic acids via Pd-catalyzed hydrocarboxylation of olefins with HCOOLi and Ac2O under mild conditions without using external CO gas.

ChemInform Abstract: Recent Advances in the Transition Metal Catalyzed Carbonylation of Alkynes, Arenes and Aryl Halides Using CO Surrogates

AbstractReview: 133 refs.

ChemInform Abstract: A Recyclable CO Surrogate in Regioselective Alkoxycarbonylation of Alkenes: Indirect Use of Carbon Dioxide.

AbstractThe CO gas stream (max.

ChemInform Abstract: Palladium‐Catalyzed Carbonylation of (Hetero)Aryl, Alkenyl and Allyl Halides by Means of N‐Hydroxysuccinimidyl Formate as CO Surrogate.

AbstractThe reaction is successfully applied in the synthesis of precursors of known acetylcholinesterase inhibitors, e.

Reversed reactivity of anilines with alkynes in the rhodium-catalysed C-H activation/carbonylation tandem.

Development of multicatalytic approach consisting of two or more mechanistically distinct catalytic steps using a single-site catalyst for rapid and straightforward access of structurally complex molecules under eco-benign conditions has significance in contemporary science. We have developed herein a rhodium-catalysed C–H activation strategy which uses an unprotected anilines and an electron-deficient alkynes to C–C bonded products as a potential intermediate in contrast to the archetypical C–N bonded products with high levels of regioselectivity. This is followed by carbonylation of C–H bond activated intermediate and subsequent annulation into quinolines has been described. This rhodium-catalysed auto-tandem reaction operates under mild, environmentally benign conditions using water as the solvent and CO surrogates as the carbonyl source with the concomitant generation of hydrogen gas. The strategy may facilitate the development of new synthetic protocols for the efficient and sustainable production of chemicals in an atom-economic way from simple, abundant starting materials.

Palladium‐Catalyzed Aminocarbonylation of Aliphatic Alkenes with N,N‐Dimethylformamide as an In Situ Source of CO

AbstractThe palladium‐catalyzed aminocarbonylation of aliphatic alkenes is presented for the first time without the need for external CO pressure. N,N‐dimethylformamide (DMF) is used as an in situ source of both the required carbon monoxide and the amine substrate. The applied palladium catalytic system is well‐known for a number of carbonylation reactions, including those with CO surrogates and tandem isomerizing carbonylations. The reaction pathway was investigated and proved to proceed by an acid‐catalyzed DMF decomposition to CO and dimethyl amine with subsequent aminocarbonylation of the alkene. Pressure‐versus‐time curves gave more insight into the correlation between acid concentration and aminocarbonylation activity. Aliphatic alkenes (terminal and internal) are transformed, also in commercial glassware, into the corresponding linear N,N‐dimethylamides with excellent selectivities. Hence, amide synthesis by aminocarbonylation moves closer to application in standard organic laboratories.

Palladium-Catalyzed Carbonylative Cyclization of Arenes by C-H Bond Activation with DMF as the Carbonyl Source.

A novel palladium-catalyzed CO-gas- and autoclave-free protocol for the synthesis of 11H-pyrido[2,1-b]quinazolin-11-ones has been developed. Quinazolinones, which are omnipresent motif in many pharmaceuticals and agrochemicals, were prepared in good yields by C-H bond activation and annulation using DMF as the CO surrogate. A (13) CO-labelled DMF control experiment demonstrated that CO gas was released from the carbonyl of DMF with acid as the promotor. The kinetic isotope effect (KIE) value indicated that the C-H activation step may not be involved in the rate-determining step. This methodology is operationally simple and showed a broad substrate scope with good to excellent yields.

ChemInform Abstract: Regioselective Pd‐Catalyzed Methoxycarbonylation of Alkenes Using Both Paraformaldehyde and Methanol as CO Surrogates.

In recent years, considerable effort has focused on the development of novel carbonylative transformations using CO surrogates. Consequently, toxic CO gas can be replaced by more convenient inorganic or organic carbonyl compounds. Herein, the first regioselective methoxycarbonylation of alkenes with paraformaldehyde and methanol as CO substitutes is reported. This new procedure is applicable to a series of alkenes in the presence of a palladium catalyst under relatively mild conditions and is highly atom efficient.

Palladium-Catalyzed Carbonylation of (Hetero)Aryl, Alkenyl and Allyl Halides by Means of N-Hydroxysuccinimidyl Formate as CO Surrogate.

An efficient Pd-catalyzed carbonylation protocol is described for the coupling of a large panel of aryl, heteroaryl, benzyl, vinyl and allyl halides 2 with the unusual N-hydroxysuccinimidyl (NHS) formate 1 as a CO surrogate to afford the corresponding valuable NHS esters 3. High conversion to the coupling products was achieved with up to 98% yield by means of Pd(OAc)2/Xantphos catalyst system.

Regioselective Pd-catalyzed methoxycarbonylation of alkenes using both paraformaldehyde and methanol as CO surrogates.

In recent years, considerable effort has focused on the development of novel carbonylative transformations using CO surrogates. Consequently, toxic CO gas can be replaced by more convenient inorganic or organic carbonyl compounds. Herein, the first regioselective methoxycarbonylation of alkenes with paraformaldehyde and methanol as CO substitutes is reported. This new procedure is applicable to a series of alkenes in the presence of a palladium catalyst under relatively mild conditions and is highly atom efficient.