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A novel, highly efficient heterogeneous palladium‐catalyzed carbonylative cyclization of aryl iodides and benzyl acetylenes has been developed under an atmospheric pressure of CO. The reaction proceeds smoothly in a bioderived solvent 2‐methyltetrahydrofuran (2‐MeTHF) at 50 °C using an MCM‐41‐anchored bidentate phosphine palladium complex [Pd(OAc)2‐MCM‐41‐P,P] as catalyst with DiPEA as base, delivering a wide variety of 3‐alkylidenefuran‐2‐ones in good to excellent yields. The Pd(OAc)2‐MCM‐41‐P,P complex can be easily recovered by a simple centrifugation and recycled more than ten times without any remarkable loss of catalytic activity. The present method not only avoids the use of toxic solvents such as benzene, toluene and THF, but also addresses the key problem of expensive palladium catalyst recovery and recycle, thus preventing palladium contamination in the final product. [ABSTRACT FROM AUTHOR]

A protocol has been developed for the synthesis of six‐ and seven‐membered ring lactams fused to coumarins through a hydroaminocarbonylation reaction catalyzed by palladium. The catalytic system (PdBr2/Xantphos) provided a strategy for the synthesis of seven‐membered ring lactams with good isolated yield and regioselectivity. Control of selectivity by the substrate in the synthesis of six‐membered ring lactams was observed. Control reactions showed the importance of the hydrogen in the cyclocarbonylation reaction, and NMR data supported the role of the hydride palladium species as a catalytic precursor. A preliminary screening of the cytotoxic activity of coumarin‐fused lactams against six cancer cell lines was evaluated. The biological tests indicated that both the size of the heterocycle and presence of a substituent on the aromatic ring affected the inhibition of cell growth. [ABSTRACT FROM AUTHOR]

Abstract Palladium-catalysed sequential one-pot synthesis of fluorenones is described. The reaction comprises intermolecular Suzuki coupling and intramolecular acid-mediated cyclisation in a one-pot procedure. The protocol is also applied to the synthesis of fluorenes using a single column purification.

The first example of a two‐state (neutral and reduced), stable electron‐accepting material and its radical anion is presented. FV‐PDI, generated from cyclocarbonylation and then a carbonyl coupling reaction, shows a largely degenerate LUMO of −4.38 eV based on the delocalization of π‐electrons across the whole molecular skeleton through a fulvalene bridge. The stability and electron affinity allow spontaneous electron transfer to afford a stable radical anion. Spectroscopic characterization and structural elucidation showed that the radical anion [FV‐PDI].− has remarkable stability and near‐infrared absorptions extending to 1200 nm. Single‐crystal X‐ray diffraction analyses revealed significant changes in the molecular shape and packing arrangement of the formed radical anion. The central C−C bond linking the two PDI halves is lengthened from approximately 1.33 to 1.43 Å, and the alternating arrangement of positively and negatively charged units favor the stable charge‐transfer complex. [ABSTRACT FROM AUTHOR]

(S)-4-Isopropyl-5,5-diphenyloxazolidin-2-one has been synthesized for the first time by the enantiospecific oxidative carbonylation of commercially available (S)-2-amino-3-methyl-1,1-diphenylbutan-1-ol. The cyclocarbonylation reaction was carried out at 100 °C in 1,2-dimethoxyethane (DME) as the solvent for 15 h, under 20 atm of a 4:1 mixture of CO–air and in the presence of the catalytic system PdI2/KI (substrate:KI:PdI2 molar ratio = 100:10:1), to give the oxazolidinone derivative in 81% isolated yield.

Abstract: An efficient and practical synthesis of isoindolo[2,1‐b]isoquinoline‐5,7‐diones through Pd‐catalyzed C−H activation/carbonylative annulation of isoquinolones with CO (1 atm) is presented. Deuterium‐labeling experiments revealed that the aryl C(sp2)−H bond activation might be the rate‐determining step. More interestingly, the title compounds could also be prepared directly from the cascade reaction of N‐methoxy benzamides and internal alkynes, as the precursors of isoquinolones, under an atmospheric pressure of carbon monoxide through a Rh/Pd relay catalysis in a user‐friendly manner. [ABSTRACT FROM AUTHOR]

A new and convenient approach to functionalized benzimidazopyrimidinones is reported. It is based on a two-step procedure starting from readily available 1-(prop-2-yn-1-yl)-1H-benzo[d]imidazol-2-amines, consisting of a multicomponent palladium-catalyzed oxidative cyclocarbonylation-alkoxycarbonylation process, followed by base-promoted isomerization of the initially formed mixture of isomeric carbonylated products. Fair to good overall yields of the final alkyl 2-(2-oxo-1,2-dihydrobenzo[4,5]imidazo[1,2-a]pyrimidin-3-yl)acetates are obtained, using different alcohols as solvent and nucleophile in the carbonylation step (carried out in the presence of 0.33-1 mol% PdI2 in conjunction with 17-50 mol% KI, at 100 °C and under 20 atm of a 4:1 mixture of CO-air) and the corresponding sodium alkoxide as base in the subsequent isomerization step (carried out in the alcoholic solvent at room temperature). The structures of a representative substrate [Nbenzyl-1-(prop-2-yn-1-yl)-1H-benzo[d]imidazol-2-amine] and a representative product [methyl 2-(1-isopentyl-2-oxo-1,2-dihydrobenzo-[4,5]imidazo[1,2-a]pyrimidin-3-yl)acetate] were confirmed by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

In their Research Article, K. Almaraz and M. Amézquita-Valencia prepared a new series of six- and seven-membered ring lactam fused to coumarin core via Pd-catalyzed hydroaminocarbonylation reaction under syngas conditions. Keywords: Cyclocarbonylation; Lactam; Palladium; Regioselectivity; Medium-sized heterocycles EN Cyclocarbonylation Lactam Palladium Regioselectivity Medium-sized heterocycles 1 1 1 08/23/23 20230821 NES 230821 B The Cover Feature b , designed by Hortensia Segura, illustrates a brave little cat (the catalyst) jumping onto a garden wall, crossing a seven-membered ring lactam fused to a coumarin scaffold. Cover Feature: Pd-Catalyzed Intramolecular Hydroaminocarbonylation of 3-Allyl-4-arylaminocoumarins: Synthesis of Six- and Seven-membered Ring Lactams Fused to the Coumarin Scaffold (ChemCatChem 16/2023). [Extracted from the article]

An efficient approach to the synthesis of fluorenones via the palladium‐catalyzed cyclocarbonylation of cyclic diaryliodoniums was developed. Our route enables facile access to fluorenones with various substituents in modest to high yields. [ABSTRACT FROM AUTHOR]

Two monocyclic members in the gracilioether family were synthesized in only three steps. The monocyclic products were further elaborated into advanced precursors to hippolachnin A and gracilioether E, respectively. Gracilioether F and the alleged structure for gracilioether I were also synthesized using a late-stage C(sp3)-H thermo-oxidation. [ABSTRACT FROM AUTHOR]

Isochromanone and benzoxepinone derivatives have been synthesized through selective cyclocarbonylation reactions respectively of 2-vinylbenzylalcohols and 2-alkynylbenzylalcohols under syn -gas condition using Pd(OAc) 2 -dppb as the catalytic system. Depending on the subtrate, different lactone structures were obtained. [Display omitted] • Cyclocarbonylation reactions of alkenyl and alkynyl benzylalcohols have been performed. • Selective cyclocarbonylation reactions by using Pd(OAc) 2 -dppb as homogeneous catalytic system. • Synthesis of isochromanones and benzoxepinones derivatives under syn -gas conditions. Heterocyclic compounds such as lactones, lactams or pyrrolidinones are employed as useful intermediates for the synthesis of biologically active products. In the past decades various preparation routes to these class of heterocycles have been described and palladium-based compounds have been regarded as the most efficient catalysts for the preparation of important cyclic compounds. In this work, novel isochromanome and benzoxepinone derivatives have been prepared and fully characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopies and gas chromatography–mass spectrometry (GC–MS) analysis. An effective homogeneous catalytic system based on palladium complex was used. Isochromanone and benzoxepinone derivatives have been synthesized through selective cyclocarbonylation reactions respectively of 2-vinylbenzylalcohols and 2-alkynylbenzylalcohols under syn -gas condition using Pd(OAc) 2 -dppb as the catalytic system. Depending on the subtrate, different lactone structures were obtained with a good selectivity for each reaction. [ABSTRACT FROM AUTHOR]

4-Arylcoumarins (4-aryl-2H-1-benzopyran-2-one), also known as neoflavones, comprise a minor subclass of naturally occurring flavonoids. Because of their broad-spectrum biological activities, arylcoumarins have been attracting the attention of the organic and medicinal chemistry communities, and are considered as an important privileged scaffold. Since the development of Pechmann condensation, a classical acid-catalyzed condensation between phenol and β-keto-carboxylic acid, several versatile and efficient synthetic approaches for 4-arylcoumarins have been reported. This review summarizes recent advances in the synthesis of the 4-arylcoumarin scaffold by classifying them based on the final bond-formation type. In particular, synthetic methods executed under mild and highly efficient conditions, such as solvent-free reactions and transition metal catalysis, are highlighted.

A highly efficient and regioselective synthetic route to 6 H-isoindolo[2,1- a]indol-6-ones and indeno[1,2- b]indol-10(5 H)-ones through the Pd-catalyzed cyclocarbonylation of 2-(2-bromoaryl)indoles under atmospheric CO pressure has been achieved. Notably, the regioselectivity of the reaction was exclusively dependent on the structural characteristics of the indole substrates. With N-unsubstituted indoles as the starting materials, the reaction afforded 6 H-isoindolo[2,1- a]indol-6-ones in good-to-excellent yields. On the other hand, with N-substituted indoles as the substrates, the reaction gave indeno[1,2- b]indol-10(5 H)-ones in a highly regioselective manner. [ABSTRACT FROM AUTHOR]

The addition of phosphonate stabilized carbon nucleophiles to acyclic (pentadienyl)iron(1+) cations proceeds predominantly at an internal carbon to afford (pentenediyl)iron complexes. Those complexes bearing an electron withdrawing group at the σ-bound carbon (i.e., 13 / 14 ) are stable and isolable, while complexes which do not contain an electron withdrawing group at the σ-bound carbon undergo CO insertion, reductive elimination and conjugation of the double bond to afford cyclohexenone products ( 21 / 22 ). Deprotonation of the phosphonate 13 / 14 or 21 and reaction with paraformaldehyde affords the olefinated products. This methodology was utilized to prepare oxygenated carvone metabolites (±)- 25 and (±)- 26 . [ABSTRACT FROM AUTHOR]

A fundamentally novel approach to bioactive quinolizinones is based on the palladium-catalyzed intramolecular cyclocarbonylation of allylamines. [Pd(Xantphos)I2], which features a very large bite angle, has been found to facilitate the rapid carbonylation of azaarene-substituted allylamines into bioactive quinolizinones in good to excellent yields. This transformation represents the first dearomative carbonylation and is proposed to proceed by palladium-catalyzed CN bond activation, dearomatization, CO insertion, and a Heck reaction. [ABSTRACT FROM AUTHOR]

The cyclocarbonylation of homoallylic alcohols, derived from α-atlantone, catalysed by [Pd(Cl 2 )L 2 ]/SnCl 2 ] system, afforded new γ and δ lactones as the main products with high selectivities. The regiochemical control depends on the nature of phosphines involved. Catalysts based on monophosphines with large cone angles such as tricyclohexyl phosphine produce the six-membered ring lactones with selectivities up to 80%, while diphosphines with wide bite angle such as xantphos are found to favor the five-membered ring lactones with up to 99% selectivity. Monocrystals of the γ and δ lactones suitable for X-ray diffraction analysis have been obtained and the stereochemistry of the lactones 5a , a ′ and 6 have been elucidated. This study is the first example of an attractive catalytic transformation of one single natural sesquiterpene easily available from bio-renewable resources to obtain either γ- or δ-lactones. [ABSTRACT FROM AUTHOR]

An N-phthalimide-protected ( ortho-aminophenyl)propiolate was prepared by the carboxylation of the corresponding silylalkyne precursor with carbon dioxide. The obtained propiolate was further transformed to various 3,4-fused 2-quinolones via cycloadditions and subsequent deprotection/lactam formation. [ABSTRACT FROM AUTHOR]

La[N(SiMe)] proves to be an efficient catalyst system for the cyclocarbonylation of 1,2-disubstituted benzenes with isocyanates. In this approach, aryl/alkyl isocyanates react with o-phenylenediamine, o-aminophenol, o-aminothiophenol, catechols and anilines ortho-substituted by CHNH and CONH to form, respectively, the corresponding benzimidazolones, benzoxazolones, benzothiazolones, benzodioxolones, 3,4-dihydroquinazolin-2(1 H)-one, and quinazolinediones. These results represent the first example of lanthanide-catalyzed carbonylation. This methodology is also applicable for the preparation of various benzannulated 1,3-diheteroatom cyclic thioketones starting from aryl/alkyl isothiocyanates or CS in good to excellent yields. Based on the results of experiments performed using an o-aminobenzamido dianion lanthanide complex, a general mechanism, involving the tandem reaction of two lanthanide-ligand bonds with one heterocumulene molecule, is proposed as well. [ABSTRACT FROM AUTHOR]

Abstract: A novel one-pot synthesis of carbazole-1,4-quinone by consecutive Pd-catalyzed cyclocarbonylation, desilylation, and oxidation reactions is described. We propose a possible mechanism of the cyclocarbonylation reaction between 3-iodo-2-propenylindole and CO (1 atm) in the presence of a tributyl(vinyl)tin and Pd-catalyst and the resulting acylpalladium species was directly coupled with a terminal alkene to produce the carbazole-1,4-quinone. To our knowledge, this is the first example of this type of reaction. A new formal total synthesis of a carbazole-1,4-quinone alkaloid, murrayaquinone A was established using this reaction. [Copyright &y& Elsevier]

An efficient procedure for the synthesis of 2-aminoisoindolin-1-ones via a palladium-catalyzed three-component reaction of 2-halobenzaldehydes, hydrazines and carbon monoxide is reported. This cyclocarbonylation process can be performed smoothly under 1 atmospheric pressure of carbon monoxide to afford 2-aminoisoindolin-1-ones in moderate to excellent yields. [ABSTRACT FROM AUTHOR]

Catalytic cyclocarbonylation reactions using a glyceraldehyde derivative as a carbonyl source are described. The rhodium( I)-catalyzed reaction of enynes with glyceraldehyde acetonide gave bicyclic cyclopentenones as the products. This presents an interesting use of a sugar alcohol derived carbon resource as well as a convenient procedure for the cyclocarbonylation of enynes. [ABSTRACT FROM AUTHOR]

Abstract: A new, efficient and practical synthesis of quinazolin-4(3H)-ones is reported via molybdenum-mediated cyclocarbonylation using microwave irradiation. These methods allow access to a wide range of quinazolin-4(3H)-ones in reasonable yields without the need for gaseous carbon monoxide and palladium catalysts. A range of reactions illustrating the wide scope of this chemistry was carried out and all proceeded in reasonable yields. [Copyright &y& Elsevier]

Abstract: Despite their utility as building blocks for the construction of a variety of nitrogen-containing heterocyclic scaffolds, the preparation of allenic amines 2 via the direct C–H amination of allenes of the general structure 1 has not been well-explored. In this report, we describe our preliminary studies on the factors that control the chemoselectivity of Rh-catalyzed aminations of allenes to give either bicyclic methylene aziridines or the desired allenic amines 2. Additionally, the conversion of selected allenic amines to α,β-unsaturated γ-lactam scaffolds via a facile Ru3(CO)12 catalyzed cyclocarbonylation is described. [Copyright &y& Elsevier]

Highly substituted lactone- and ester-containing furans have been prepared by the efficient palladium-catalyzed intramolecular cyclocarbonylation or intermolecular carboalkoxylation, respectively, of hydroxyl-containing 3-iodofurans, readily prepared by the iodocyclization of 2-(1-alkynyl)-2-alken-1-ones in the presence of various diols. [ABSTRACT FROM AUTHOR]

A diverging diversity-oriented synthesis (DOS) strategy using an allene-containing tryptophan as a key starting material was investigated. An allene-yne substituted derivative of tryptophan 12 gave indolylmethylazabicyclooctadiene 17 when subjected to a microwave-assisted allenic [2 + 2] cycloaddition reaction. This same tryptophan-derived precursor afforded an indolylmethyldihydrocyclopentapyridinone 14 when subjected to a rhodium(I)-catalyzed cyclocarbonylation reaction and an indolylmethylpyrrolidinocyclopentenones 16 when reacted with molybdenum hexacarbonyl. Construction of allenic tetrahydro-β-carboline scaffolds via a Pictet-Spengler reaction and subsequent silver(I)-catalyzed cycloisomerization afforded tetrahydroindolizinoindoles (21). Attachment of allene and alkyne groups to the tetrahydro-β-carboline, followed by a microwave-assisted allenic [2 + 2] cycloaddition reaction, provided tetrahydrocyclobutaindoloquinolizinones 24 and the tetrahydrocyclopentenone indolizinoindolone 26 when reacted with molybdenum hexacarbonyl. These six scaffolds were used as templates for the construction of a virtual library of 11748 compounds employing 44 indoles, 12 aldehydes, and 51 alkynes. Diversity analyses using a combination of cell-based chemistry space computations using BCUT (Burden (B) CAS (C) Pearlman at the University of Texas (UT)) metrics and Tanimoto coefficient (Tc) similarity calculations using two-dimensional (2D) fingerprints showed that the compounds in the virtual library occupied new chemical space when compared to the 327?000 compounds in the molecular libraries small molecule repository (MLSMR). A subset of fifty-three compounds was identified from the virtual library using the DVS package of Sybyl 8.0; this subset represents the most diverse compounds within the chemical space defined by these compounds and will be synthesized and screened for biological activity. [ABSTRACT FROM AUTHOR]

Abstract: 1-Isoindolinone derivatives were synthesised in high yields (up to 89%) by using 2-iodobenzyl bromide and 2-iodobenzylamine as bifunctional substrates in palladium-catalysed carbonylation. Depending on the N-nucleophiles, two types of compounds were synthesised with 2-iodobenzyl bromide: the use of primary amines, including amino acid methylesters, resulted in the formation of N-substituted 1-isoindolinones, while secondary amines react both with the benzyl bromide and iodoarene moieties resulting in the corresponding ortho-(N-piperidino/morpholinomethyl)-benzamides. The parent 1-isoindolinone was obtained in a facile, highly chemoselective intramolecular aminocarbonylation of 2-iodobenzylamine. The mechanistic details of the ring-closure reaction and the conditions leading to side-products are discussed as well. [ABSTRACT FROM AUTHOR]

Abstract: Cyclocarbonylation reactions proceed mainly by the coupling reactions of carbonylation components with cyclization components having an unsaturated π-electron bond, in the presence of transition metal compounds. The representative reactions are cyclocarbonylation of alkynes by carbon monoxide such as Pauson–Khand reactions, hetero Pauson–Khand reactions, cyclocarbonylation of alkynyl alcohols, cyclocarbonylation of alkynyl amines, cyclocarbonylative alkyne–alkyne coupling reactions, and reductive cyclocarbonylation of alkynes. The other reactions are cyclocarbonylation of alkenes by carbon monoxide such as alkene–alkene coupling reactions, cyclocarbonylation with aldehydes, ketones, amines or imines, cyclocarbonylation of alkenyl alcohols. Carbonylation via cyclometalation, carbonylative ring expansion reactions, cyclocarbonylation by aldehydes, carboxylic acids or carboxylic acid esters are also cyclocarbonylation reactions. These reactions are conveniently used for organic syntheses, especially, for the syntheses of pharmaceutical intermediates. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic activity of a Co2(CO)8/dppe (C3) solution system is compared with binuclear complexes Co2(CO)6[P(Ph)3]2 (C1) and Co2(CO)6[P(OPh)3]2 (C2). The C3 system, likewise C1 and C2, catalyses the Pauson–Khand (PK) reaction employing strained olefins and does not promote double carbonylation as occurs with C2. Under more drastic reaction conditions, the use of C2 and C3 in presence of less structural strained olefins yields a mixture of products: PK and alkyne cyclotrimerization leading to aromatic compounds. Alkyne cyclotrimerization under these PK reaction conditions appears to be the first example reported. IR studies suggest the formation of an alkynyl–Co2(CO)4-μ2-(Ph)2PCH2CH2P(Ph)2 symmetric complex as the catalytic species active in the system. [Copyright &y& Elsevier]

In this paper, we demonstrate a successful conversion of alkynyl allenamides to triene-containing heterocycles via a rhodium(I)-catalyzed cycloisomerization reaction. [ABSTRACT FROM AUTHOR]

Abstract: In the diastereoselective cyclocarbonylation of isopulegol and isolimonene catalysed by the non-chiral [PdCl2L2] palladium complexes (L=PPh3, L2 =bis(diphenylphosphino)-butane or -ferrocene), the diastereoisomeric excess is enhanced by a factor of 1.5–2 when toluene is substituted by chloro-solvents. A less significant effect is noted when using more coordinating solvents such as acetonitrile and THF. In chloro-solvents reaction rates are faster than in toluene, isopropanol, acetonitrile or THF. [Copyright &y& Elsevier]

Abstract: The efficient Ru3(CO)12-catalyzed reductive cyclocarbonylation of internal alkynes in the presence of water under the moderate CO pressure to afford 3,4-disubstituted furan-2(5H)-ones in good to excellent yields is described. [Copyright &y& Elsevier]

Abstract: The reaction of 6-amino-1,3-dimethyluracil with substituted ferrocenyl-ketoalkynes using nickel cyanide as homogeneous catalyst precursor in aqueous alkaline medium, affords 5-substituted-7-ferrocenyl-dioxopyrido[2,3-d]pyrimidines derivatives, in moderate yields under mild conditions. [Copyright &y& Elsevier]

Abstract: The catalytic activity of previously formed Co2(CO)6[P(Ph)3]2 (1) was compared with Co2(CO)8 and the system formed by Co2(CO)8 plus PPh3 in the intermolecular Pauson–Khand (PK) reaction between norbornadiene and phenylacetylene. The effects of pressure, catalyst concentration and temperature were also studied. Additionally, the catalytic activity of complex 1 was compared with Co2(CO)6[P(OPh)3]2 (2) in the intermolecular PK reaction between strained alkenes and terminal and non-terminal alkynes. Both catalysts are very stable, quite efficient and interestingly complex 2 leads to double PK reaction. The results indicate that these complexes are attractive alternatives to Co2(CO)8 as catalyst and in addition, complex 2 is an alternative catalyst for double cyclocarbonylation reaction. [Copyright &y& Elsevier]

The asymmetric cyclocarbonylation reaction of allyl naphthol catalyzed by palladium complexes and chiral phosphine is reported. The reaction was performed under syn-gas conditions at relatively mild experimental conditions (80–100 °C, 300–600 psi (1 psi = 6.895 kPa)) in CH2Cl2 as the solvent. [ABSTRACT FROM AUTHOR]

Carbonylation of azobenzene derivatives catalyzed by rhodium carbonyls in the presence of nitrobenzene as a hydrogen acceptor gave a four-ring heterocyclic product, indazolo[2,1-a]indazole-6,12-dione, in a good yield, which is derived from a novel cyclocarbonylation with C–H bond activation and CO insertion at each benzene nucleus of azobenzene. [Copyright &y& Elsevier]

Abstract: PdCl2(PCy3)2-catalyzed cyclocarbonylative coupling of ortho-chloro arylketimines with CO has been investigated to develop an efficient method for the synthesis of isoindolin-1-ones. The developed synthetic method has the advantages of having easily available starting materials, high atom-economy, and high selectivity. [Copyright &y& Elsevier]

Palladium-catalyzed intermolecular cyclocarbonylation of 2-iodobenzylamines with Michael acceptors produces 1,2,3,4- tetrahydro-5H-2-benzazepin-5-one derivatives in moderate to good yields. This methodology enables the direct preparation of highly functionalized 1,2,3,4-tetrahydro-5H-2-benzazepin-5-ones from readily available starting materials. [ABSTRACT FROM AUTHOR]

Abstract: Palladium-catalyzed intermolecular cyclocarbonylation of diethyl (2-iodoaryl)malonates with N-tosylimines produces 4-ethoxycarbonyl-3,4-dihydroisoquinolin-1(2H)-ones in moderate to good yields. This reaction is highly stereoselective. This protocol involves Mannich addition, and subsequent cyclocarbonylation. [Copyright &y& Elsevier]