Carbonylation Of Alkynes Research Articles

Anion Relay Chemistry Enables Stereoselective Carbonyl-Alkyne Metathesis Reactions.

Dithiane chemistry is increasingly advantageous in the development of novel anion relay chemistry (ARC) modes that harness their umpolung properties to address new chemical challenges. Herein, we report the use of an ARC strategy to promote the regioselective carbonyl alkyne metathesis (CAM) of various carbonyl compounds with alkynyl 1,3-dithianes. Notably, this ARC transformation provides a platform for obtaining stereodefined polysubstituted 1,3-dienes.

Relay catalysis over Pd-catalysts induced by two divergent ligands for cascade bis-alkoxycarbonylation of alkynes

The mono-metal relay catalysis is a good strategy for one-pot multi-step cascade process in which the specific catalysis can be switched upon the ligand exchange to match the requirements for each independent reaction but without mutual interference and quenching problem. Herein, the one-pot cascade bis-alkoxycarbonylation of terminal alkynes was achieved by taking advantages of the mono-metallic (Pd) relay catalysis, wherein the two kinds of divergent di-phosphines of L1 and DTBPMB were involved. In this Pd(OAc)2-L1-DTBPMB system, due to the steric bulkiness of L1 and DTBPMB, the two type of catalysts including Pd(OAc)2-L1 and Pd(OAc)2-DTBPMB co-existed independently and compatibly. Pd(OAc)2-L1 system was only in charge of the first-step carbonylation of alkynes towards the branched α,β-unsaturated esters with gem-positioned double bond. Subsequent, Pd(OAc)2-DTBPMB system took over the carbonylation of the branched α,β-unsaturated esters to afford the target diesters. It was indicated Pd(OAc)2-L1 system was an efficient and stable catalyst which could be recycled upon 15 runs for the first-step carbonylation. Anyway, Pd(OAc)2-DTBPMB system easily underwent deactivation, which degraded the recyclability of the Pd(OAc)2-L1-DTBPMB coupling system for this cascade bis-alkoxycarbonylation.

Co/SiO2 Catalyst for Methoxycarbonylation of Acetylene: On Catalytic Performance and Active Species.

Reppe carbonylation of acetylene is an atom-economic and non-petroleum approach to synthesize acrylic acid and acrylate esters, which are key intermediates in the textile, leather finishing, and polymer industries. In the present work, a noble metal-free Co@SiO2 catalyst was prepared and evaluated in the methoxycarbonylation reaction of acetylene. It was discovered that pretreatment of the catalyst by different reductants (i.e., C2H2, CO, H2, and syngas) greatly improved the catalytic activity, of which Co/SiO2-H2 demonstrated the best performance under conditions of 160 °C, 0.05 MPa C2H2, 4 MPa CO, and 1 h, affording a production rate of 4.38 gMA+MP gcat-1 h-1 for methyl acrylate (MA) and methyl propionate (MP) and 0.91 gDMS gcat-1 h-1 for dimethyl succinate (DMS), respectively. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and diffuse reflectance infrared Fourier transform spectra of CO adsorption (CO-DRIFTS) measurements revealed that an H2 reduction decreased the size of the Co nanoparticles and promoted the formation of hollow architectures, leading to an increase in the metal surface area and CO adsorption on the catalyst. The hot filtration experiment confirmed that Co2(CO)8 was generated in situ during the reaction or at the pre-activation stage, which served as the genuine active species. Our work provides a facile and convenient approach to the in situ synthetization of Co2(CO)8 for a Reppe carbonylation reaction.

The synthesis of alk-2-ynl Weinreb amides via Pd/Cu-catalysed oxidative carbonylation of terminal alkynes.

Synthesis of alk-2-ynl-Weinreb amides via Pd-catalyzed oxidative carbonylation of terminal alkynes and N,O-dimethylhydroxylamine hydrochloride at room temperature under low CO/O2 pressure is reported for the first time. This protocol offers tolerance of various functional groups under mild reaction conditions. The protocol incorporates aromatic- and aliphatic-substituted alkynes through a one-step oxidative carbonylative route toward desired alkynyl Weinreb amides, which are of considerable importance as valuable synthetic building blocks.

Base‐Promoted Difunctionalization of Alkynes: One‐Pot Synthesis of Polysubstituted Chromones

AbstractA transition‐metal‐free one‐pot procedure for the difunctionalization of alkynes by C−C triple bond oxidation and transformation towards chromone derivatives has been developed. It involves cascade reactions for carbonylation of alkynes, base‐promoted C−C σ‐bond cleavage, and intramolecular cyclization. This procedure provides an efficient protocol for the synthesis of polysubstituted chromones from readily available starting materials.

Regio- and Stereoselective Switchable Synthesis of (E)- and (Z)-N-Carbonylvinylated Pyrazoles.

Regio- and stereoselective switchable synthesis of (E)- and (Z)-N-carbonylvinylated pyrazoles is first developed by using the Michael addition reaction of pyrazoles and conjugated carbonyl alkynes. Ag2CO3 plays a key role in the switchable synthesis of (E)- and (Z)-N-carbonylvinylated pyrazoles. Ag2CO3-free reactions lead to thermodynamically stable (E)-N-carbonylvinylated pyrazoles in excellent yields whereas reactions with Ag2CO3 give (Z)-N-carbonylvinylated pyrazoles in good yields. It is noteworthy that (E)- or (Z)-N1-carbonylvinylated pyrazoles are obtained with high regioselectivity when asymmetrically substituted pyrazoles react with conjugated carbonyl alkynes. The method can also extend to the gram scale. A plausible mechanism is proposed on the basis of the detailed studies, wherein Ag+ acts as coordination guidance.

Direct Access to α,β-Alkynylamides via Pd-Catalyzed Carbonylation of Terminal Alkynes with Amines Using Chloroform as the CO Surrogate.

We describe the first-time use of a palladium-di(1-adamantyl)-n-butylphosphine catalytic system for the synthesis of alk-2-ynamides from terminal alkynes via aminocarbonylation reaction. This method avoids the direct use of toxic CO gas by utilizing chloroform as an in situ CO source. The aminocarbonylation of both aromatic and aliphatic electron-rich alkyne nucleophiles is reported for the first time. The mild condition provides alk-2-ynamides within 50 min under microwave irradiation at 80 °C.

Dioxygen Activation by a Bioinspired Tungsten(IV) Complex.

An increasing number of discovered tungstoenzymes raises interest in the biomimetic chemistry of tungsten complexes in oxidation states +IV, +V, and +VI. Bioinspired (sulfur-rich) tungsten(VI) dioxido complexes are relatively prevalent in literature. Still, their energetically demanding reduction directly correlates with a small number of known tungsten(IV) oxido complexes, whose chemistry is not well explored. In this paper, a reduction of the [WO2(6-MePyS)2] (6-MePyS = 6-methylpyridine-2-thiolate) complex with PMe3 to a phosphine-stabilized tungsten(IV) oxido complex [WO(6-MePyS)2(PMe3)2] is described. This tungsten(IV) complex partially releases one PMe3 ligand in solution, creating a vacant coordination site capable of activating dioxygen to form [WO2(6-MePyS)2] and OPMe3. Therefore, [WO2(6-MePyS)2] can be used as a catalyst for the aerobic oxidation of PMe3, rendering this complex a rare example of a tungsten system utilizing dioxygen in homogeneous catalysis. Additionally, the investigation of the reactivity of the tungsten(IV) oxido complex with acetylene, substrate of a tungstoenzyme acetylene hydratase (AH), revealed the formation of the tungsten(IV) acetylene adduct. Although this adduct was previously reported as an oxidation product of the tungsten(II) acetylene carbonyl complex, here it is obtained via substitution at the sulfur-rich tungsten(IV) center, mimicking the initial step of the first shell mechanism for AH as suggested by computational studies.

Palladium-Catalyzed Carbonylation for General Synthesis of Aurones Using CO2.

The carbonylation of alkynes using CO2 to generate aurones is to date unknown. In this study, a palladium-catalyzed carbonylation of terminal aromatic alkynes and the waste hydrosilane, poly(methylhydrosiloxane) (PMHS), is carried out with 2-iodophenol using CO2 to produce aurones. A variety of terminal alkynes and substituted 2-iodophenols are transformed into aurones in good yields. Preliminary mechanistic studies indicate that silyl formate, generated from CO2 and PMHS, plays a crucial role in the carbonylation reaction.

Construction of 4-Acyl-2-quinolones through Sc(OTf)3-Catalyzed Ring-Closing Alkyne-Carbonyl Metathesis.

An atom-economical protocol to construct densely substituted 4-acyl-2-quinolones from N-(2-alkynylphenyl)-α-ketoamides has been developed through Sc(OTf)3-catalyzed ring-closing alkyne-carbonyl metathesis. Mechanistic experimental studies support that coordinative interaction between Sc(OTf))3 and the substrate, the formation of an oxetene intermediate, and an electrocyclic ring-opening of the oxetene might be involved.

Metal-free synthesis of N-vinyl sulfoximines via DABCO-participated Michael addition of terminal carbonyl alkynes with N-chlorosulfoximines

A new method has been developed to prepare N-vinyl sulfoximines via a DABCO-participated Michael addition of carbonyl alkynes with N-chlorosulfoximines in the absence of metal. Various N-chlorosulfoximines and carbonyl alkynes were used as substrates in this novel protocol successfully, and only the corresponding (E)-N-vinyl sulfoximines were afforded in moderate yields. The establishment of this new synthetic method that featured good compatibility with air and high efficiency as well as the avoidance of transition metal would provide an alterative access to functional N-vinyl sulfoximines under green and simple conditions.

Access to Dibenzo[c,e]azonines by Iron-Catalyzed Alkyne–Carbonyl Metathesis

Key words iron catalysis - alkynes - dibenzoazonines - cyclization - metathesis

Direct difunctional carbonylation of terminal alkynes with sodium sulfinates to access olefin sulfonyl methyl esters under metal-free conditions

A metal-free difunctional carbonylation procedure toward the synthesis of olefin sulfonyl methyl esters has been developed to give the desired olefin sulfonyl methyl esters in moderate to good yields.

Regioselective catalytic carbonylation and borylation of alkynes with aryldiazonium salts toward α-unsubstituted β-boryl ketones.

A new Pd/Cu-catalyzed carbonylation and borylation of alkynes with aryldiazonium salts toward α-unsubstituted β-boryl ketones with complete regioselectivity has been developed. This transformation shows broad substrate scope and excellent functional-group tolerance. Moreover, the obtained 1,2-carbonylboration products provide substantial opportunities for further transformations which cannot be obtained by known carbonylation procedures. Preliminary mechanistic studies indicate that the three hydrogen atoms of the products originated from ethyl acetate.

Metal-Free Synthesis of N-Vinyl Sulfoximines Via Dabco-Participated Micheal Addition of Terminal Carbonyl Alkynes with N-Chlorosulfoximines

Metal-Free Synthesis of N-Vinyl Sulfoximines Via Dabco-Participated Micheal Addition of Terminal Carbonyl Alkynes with N-Chlorosulfoximines

Thiophosphonium–Alkyne Cycloaddition Reactions: A Heavy Congener of the Carbonyl–Alkyne Metathesis

While the metathesis reaction between alkynes and thiocarbonyl compounds has been thoroughly studied, the reactivity of alkynes with isoelectronic main group R2E=S compounds is rarely reported and unknown for [R2P=S]+ analogues. We show that thiophosphonium ions, which are the isoelectronic phosphorus congeners to thiocarbonyl compounds, undergo [2 + 2]-cycloaddition reactions with different alkynes to generate 1,2-thiaphosphete ions. The four-membered ring species are in an equilibrium state with the corresponding P=C–C=S heterodiene structure and thus undergo hetero-Diels–Alder reactions with acetonitrile. Heteroatom and substituent effects on the energy profile of the 1,2-thiaphosphete formation were elucidated by means of quantum chemical methods.

Electrochemical Palladium-Catalyzed Oxidative Sonogashira Carbonylation of Arylhydrazines and Alkynes to Ynones.

Oxidative carbonylation using carbon monoxide has evolved as an attractive tool to valuable carbonyl-containing compounds, while mixing CO with a stoichiometric amount of a chemical oxidant especially oxygen is hazardous and limits its application in scale-up synthesis. By employing anodic oxidation, we developed an electrochemical palladium-catalyzed oxidative carbonylation of arylhydrazines with alkynes, which is regarded as an alternative supplement of the carbonylative Sonogashira reaction. Combining an undivided cell with constant current mode, oxygen-free conditions avoids the explosion hazard of CO. A diversity of ynones are efficiently obtained using accessible arylhydrazines and alkynes under copper-free conditions. A possible mechanism of the electrochemical Pd(0)/Pd(II) cycle is rationalized based upon cyclic voltammetry, kinetic studies, and intermediates experiments.

Iron-catalyzed alkyne-carbonyl metathesis for the synthesis of 6,7-dihydro-5H-dibenzo[c,e]azonines.

The synthesis of nine-membered rings via alkyne-carbonyl metathesis is reported. The alkyne and acetal units contained in a biaryl substrate undergo the intramolecular alkyne-carbonyl metathesis reaction under FeCl3-catalysis to furnish the unexplored 6,7-dihydro-5H-dibenzo[c,e]azonines. The method provides an alternative to existing routes to nine-membered rings with cheap, non-toxic iron catalysts and milder conditions.

Solvent-controlled two-step one-pot syntheses of α-X (X = Br or Cl) enamino ketones/esters and 3-(2,5-dioxopyrrolidin-1-yl)acrylate by using terminal carbonyl alkynes.

A new two-step one-pot aminobromination/chlorination of carbonyl alkynes has been achieved via a Michael addition of aliphatic secondary amines and subsequent β-bromination/chlorination of the obtained enamines to afford various α-X (X = Br or Cl) enamino ketones/esters in moderate to good yields. A solvent-controllable protocol has been developed to produce versatile 3-(2,5-dioxopyrrolidin-1-yl)acrylates in moderate yields by using toluene as the solvent and chain alkyl propiolates as alkynyl substrates.

Catalyst in Acetylene Carbonylation: From Homogeneous to Heterogeneous

Catalyst in Acetylene Carbonylation: From Homogeneous to Heterogeneous