Palladium-Catalyzed Carbonylative Cyclization Research Articles

Enhanced Selectivity in 4-Quinolone Formation: A Dual-Base System for Palladium-Catalyzed Carbonylative Cyclization with Fe(CO)5.

The use of gaseous CO in Pd-catalyzed carbonylative quinolone synthesis presents challenges related to safety and precise pressure control. In response, a streamlined non-gaseous synthesis of 4-quinolone compounds has been developed. This study introduces a tunable CO-releasing system utilizing Fe(CO)5 activated by a dual-base system of piperazine and triethylamine. This alternative liquid CO resource facilitates the palladium-catalyzed carbonylative C-C coupling and subsequent intramolecular cyclization. By tuning the tandem kinetics of carbonylation and cyclization, this non-gaseous method achieves the successful synthesis of 22 distinct 4-quinolones with excellent yields. This is achieved through the three-component condensation of sub-stoichiometric amounts of Fe(CO)5 with 2-iodoaniline and terminal alkynes. Operando mechanistic studies have revealed a novel CO transfer mechanism that facilitates homogeneous carbonylative cyclization, distinguishing this method from traditional techniques. In addition to addressing safety concerns, this approach also provides precise control over selectivity, with significant implications for pharmaceutical research and the efficient synthesis of pharmaceutical and bioactive compounds.

Carbonylative Synthesis of Fused Quinoxalinones via Palladium-Catalyzed Cascade Cyclization of 2-Heteroaryl Iodobenzene and NaN3

A facile and straightforward approach for the synthesis of fused quinoxalinones via palladium-catalyzed cascade carbonylative cyclization of 2-heteroaryl iodobenzene and NaN3 has been achieved. The transformation might undergo cascade carbonylation, formation of acyl azide, a Curtius rearrangement, and an intramolecular cyclization sequence. The obtained heterocycle products can be easily transformed into other structurally diverse valuable compounds, which demonstrates the synthetic utility of the developed protocol.

Synthesis of β-Lactams by Palladium-Catalyzed Carbonylative Cyclization of Methylarenes and Imines

Key words aldimines - carbon monoxide - C–H bond activation - β-lactams - palladium catalysis

Palladium-Catalyzed Carbonylative Synthesis of Amide-Containing Indolo[2,1-a]isoquinolines from Alkene-Tethered Indoles and Nitroarenes

In this new procedure, amide-containing indolo[2,1-a]isoquinoline scaffolds were prepared by palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with nitroarenes. By using Mo(CO)6 as the CO source and reductant and nitroarenes as the nitrogen source, this reaction produced various amide-containing indolo[2,1-a]isoquinoline derivatives in good yields in general. Furthermore, the late-stage modifications of bioactive molecules using this protocol were demonstrated as well.

Palladium-catalyzed four-component cascade carbonylative cyclization to access carbonyl-bridged bisheterocycles

We developed a palladium-catalyzed four-component carbonylative cyclization of alkenyl-tethered aryl iodides, trifluoroacetimidoyl chlorides and propargyl amines for the construction of carbonyl-bridged bisheterocycles.

Palladium-Catalyzed Chemodivergent Carbonylation of ortho-Bromoarylimine to Biisoindolinones and Spiroisoindolinones.

We herein report a palladium-catalyzed carbonylative cyclization reaction of ortho-bromoarylimines that allows for the chemodivergent synthesis of functionalized biisoindolinones and spirocyclic isoindolinones. Either product could be selectively obtained by switching the reaction temperatures and ligands, and the biisoindolinone products could be afforded facilely with catalyst loadings as low as 0.05 mol %. Further transformation of the biisoindolinone product is also described, which represents a novel and concise approach to the biisoindoline diamine ligand.

Recyclable Palladium-Catalyzed Carbonylative Cyclization of Aryl Iodides and 2-Hydroxyacetophenones towards Flavones

AbstractA highly efficient heterogeneous palladium-catalyzed carbonylative cyclization of aryl iodides and 2-hydroxyacetophenones is developed. The reaction proceeds efficiently in DMSO at 120 °C under 3 bar of carbon monoxide by using 2 mol% of an MCM-41-immobilized bidentate phosphine palladium complex [MCM-41-2P-Pd(OAc)2] as the catalyst and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the base, providing a general, efficient and practical approach for the assembly of a wide variety of flavones in mostly good to high yields from readily available starting materials. This supported palladium catalyst can be easily recovered via centrifugation of the reaction mixture and recycled more than nine times without any significant loss of its catalytic efficiency.

Palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with phenols or arylboronic acids: Construction of carbonyl-containing indolo[2,1-a]isoquinoline derivatives

A novel palladium-catalyzed carbonylative cyclization of alkene-tethered indoles with phenols or arylboronic acids is described, which provides a facile approach to access indolo[2,1-a]isoquinoline scaffolds. This method employs benzene-1,3,5-triyl triformate (TFBen) as the CO surrogate for the incorporation of a carbonyl group into indolo[2,1-a]isoquinoline scaffolds, and a variety of carbonyl-containing indolo[2,1-a]isoquinoline derivatives are prepared in good yields.

Palladium-catalyzed domino carbonylative cyclization to access functionalized heterocycles

A novel palladium-catalyzed domino carbonylative cyclization of alkene-tethered indole derivatives with alkyne-tethered nucleophiles has been developed, which provides a straightforward and efficient platform for the rapid construction of functionalized heterocycles. By using benzene-1,3,5-triyl triformate (TFBen) as the CO source, this domino reaction proceeded smoothly with the consecutive formation of three CC bonds and one C-X bond to furnish a variety of biologically relevant indolo[2,1-a]isoquinoline-indole and indolo[2,1-a]isoquinoline-dihydrobenzofuran derivatives in good yields.

Palladium-Catalyzed Domino Carbopalladation/Carbonylative Cyclization: Synthesis of Heterocycles bearing Oxindoles and 3-Acylbenzofuran/3-Acylindole Moieties

A novel and straightforward methodology for palladium-catalyzed carbopalladation-initiated domino carbonylative cyclization to construct bisheterocycles has been established. With TFBen as an efficient and convenient CO source, the protocol is capable of generating oxindole and 3-acylbenzofuran/3-acylindole moieties from the corresponding N-(o-iodoaryl)acrylamides and o-alkynylphenols/o-alkynylanilines with the formation of three C-C bonds and one C-O/C-N bond in a single one-step operation. A wide range of bisheterocycles bearing oxindoles and 3-acylbenzofurans/3-acylindoles were prepared in moderate to excellent yields with good functional group tolerance.

Supported palladium-catalyzed carbonylative cyclization of 2-bromonitrobenzenes and alkynes to access quinolin-4(1H)-ones

A palladium supported on graphitic carbon nitride (Pd/g-C3N4) catalyzed carbonylative cyclization of 2-bromonitrobenzenes and alkynes has been developed for the expedite construction of quinolin-4(1H)-one scaffolds. By using a low loading heterogeneous palladium catalyst, Mo(CO)6 as both the CO surrogate and the reductant, and nitroarenes as the nitrogen source, the reaction proceeded well to give a variety of quinolin-4(1H)-ones in good to excellent yields.

Additive-Controlled Divergent Synthesis of Indole and 4H-Benzo[d][1,3]oxazine Derivatives: Palladium-Catalyzed Carbonylative Cyclization of 2-Alkynylanilines and Benzyl Chlorides.

A palladium-catalyzed divergent carbonylative synthesis of indoles and 4H-benzo[d][1,3]oxazines from 2-alkynylanilines and benzyl chlorides with benzene-1,3,5-triyl triformate (TFBen) as the CO source has been developed. The reaction using AlCl3 as the additive produced various indoles in high yields, while a series of 4H-benzo[d][1,3]oxazines was achieved in moderate yields with AcOH as the additive.

Palladium-catalyzed carbonylative synthesis of indole-3-carboxamides from 2-ethynylanilines and nitroarenes

A facile and straightforward approach for the expedite construction of indole-3-carboxamide skeletons via a palladium-catalyzed carbonylative cyclization of 2-ethynylanilines with nitroarenes has been developed.

Palladium-catalyzed carbonylative synthesis of 3-arylquinolin-2(1H)-ones from benzyl chlorides and o-nitrobenzaldehydes

• A general and straightforward palladium-catalyzed aminocarbonylation procedure of benzyl chlorides have been developed. • o- nitrobenzaldehydes have been used as stable nitrogen sources for the synthesis of 3-arylquinolin-2(1 H )-ones. • Mo(CO) 6 has been used both as CO precursor and reductant. A palladium-catalyzed carbonylative cyclization of benzyl chlorides with o- nitrobenzaldehydes has been developed for the synthesis of 3-arylquinolin-2(1 H )-ones. Mo(CO) 6 played a dual role as both a CO surrogate and a reductant in this carbonylative transformation.

Palladium-catalyzed carbonylative cyclization of 2-alkynylanilines and aryl iodides to accessN-acyl indoles

A palladium-catalyzed carbonylative synthesis ofN-acyl indoles from 2-alkynylanilines and aryl iodides has been developed.

Palladium-catalyzed carbonylative cyclization of benzyl chlorides with anthranils for the synthesis of 3-arylquinolin-2(1H)-ones.

An efficient carbonylative procedure for the synthesis of 3-arylquinoin-2(1H)-ones has been established. Through a palladium-catalyzed aminocarbonylation of benzyl chlorides with anthranils, a variety of 3-arylquinoin-2(1H)-one products were obtained in moderate to excellent yields with good functional group tolerance.

Chelating Group Enabled Palladium-Catalyzed Regiodivergent Carbonylative Synthesis of 2,3-Dihydroquinolin-4(1H)-ones.

A new procedure on palladium-catalyzed carbonylative cyclization of N-(2-pyridyl)sulfonyl (N-SO2 Py)-2-iodoanilines with terminal alkenes has been developed for the rapid construction of dihydroquinolin-4(1H)-one scaffolds. Enabled by the chelating group and using benzene-1,3,5-triyl triformate (TFBen) as the CO source, both aromatic and aliphatic alkenes were smoothly transformed into the corresponding 2,3-dihydroquinolin-4(1H)-ones in good yields with excellent regioselectivities. Notably, the reaction of aromatic alkenes produces 2-aryl-2,3-dihydroquinolin-4(1H)-ones, while 3-alkyl-2,3-dihydroquinolin-4(1H)-ones were obtained when aliphatic alkenes were used. This protocol has been applied in the synthesis of antitumor agent A as well.

Palladium-Catalyzed Four-Component Carbonylative Cyclization Reaction of Trifluoroacetimidoyl Chlorides, Propargyl Amines, and Diaryliodonium Salts: Access to Trifluoromethyl-Containing Trisubstituted Imidazoles.

A palladium-catalyzed four-component carbonylative cyclization reaction for the expeditious construction of trifluoromethyl-containing trisubstituted imidazoles has been achieved. With readily accessible trifluoroacetimidoyl chlorides, propargyl amines, and diaryliodonium salts as the starting materials, the carbonylative transformation proceeds smoothly under mild conditions to enable the formation of multifunctionalized imidazole molecules in a one-pot, one-step manner. Diaryliodonium salts serve as both oxidants and aryl sources in the reaction.

Continuous Palladium-Catalyzed Carbonylative Cyclization Using Iron Pentacarbonyl as a CO Source

Key words domino reaction - alkoxycarbonylation - aminocarbonylation - carbon monoxide - iron pentacarbonyl - palladium catalysis

Palladium-Catalyzed Double Carbonylative Cyclization of Benzoins: Synthesis and Photoluminescence of Bis-Ester-Bridged Stilbenes.

A palladium-catalyzed double carbonylative cyclization of benzoins has been developed, which realizes the synthesis of bis-ester-bridged stilbenes just in two steps from aldehydes. Thus, the obtained fully fused tetracyclic π-systems have a pyrano[3,2- b]pyran-2,6-dione (PPD) core on their center, showing two reversible reductions at low potentials. In addition, their photoluminescence properties are strikingly affected by the aromatic rings fused to the PPD core; bis- thieno-fused PPDs are found to be excellent fluorophores with quantum yields up to 0.98.