Terminal Propargylic Alcohols Research Articles

Theoretical studies on the mechanisms and origins of substituent effects in CuBr-catalyzed three-component tandem reactions of terminal propargyl alcohols, aldehydes and amines

The CuBr-catalyzed A3-coupling-based tandem reactions of terminal propargyl alcohols, aldehydes and amines to synthesize five-membered dihydrofuran P1, disubstituted furan P2 and six-membered pyrone P3 have been developed. In this work, density functional theory (DFT) calculations have been performed to uncover the detailed reaction mechanisms and the substituent effects on the transformation of dihydrofuran P1 to pyrone P3. Computational results suggest that the catalytic cycle of dihydrofuran P1 is divided into three main processes: A3-coupling, isomerization and intramolecular cyclization. The generation of disubstituted furan P2 from dihydrofuran P1 proceeds via N-methylation and deprotonation steps. The transformation of five-membered dihydrofuran P1 to six-membered pyrone P3 is affected by the substituents R on substrate aldehyde 2. When R = OEt this transformation proceeds smoothly, undergoing the favorable OEt departure pathway. In contrast, the departure pathway is unworkable for Ph- and Me-substituted aldehydes due to the lack of hydrogen-bonding stabilization. They could only follow 1,2-R migration pathways. However, the high activation barriers in the migration pathways for the two aldehydes render the transformation infeasible. The results also reveal that silica gel acts as a significantly important hydrogen bond partner to stabilize the complexes in the transformation process. The theoretical research contributes to deeper insights into the mechanisms and the origins of substituent effects on the transformation between different heterocycles of the title reaction, which would promote the further development and design of the five- and six-membered oxygen-containing heterocycles.

Solvent-Dependent Assembly and Magnetic Relaxation Behaviors of [Cu4I3] Cluster-Based Lanthanide MOFs: Acting as Efficient Catalysts for Carbon Dioxide Conversion with Propargylic Alcohols.

Two structurally similar metal-organic frameworks (MOFs) [Dy2Cu4I3(IN)7(DMF)2]·DMF (1) and [Dy2Cu4I3(IN)7(DMA)2]·DMA (2) (HIN = isonicotinic acid) feathering different coordinated solvent molecules were successfully isolated by tuning the types of solvents in the reaction system. Structural tests indicate that 1 and 2 are both built from 1D Dy(III) chains and copper iodide clusters [Cu4I3], generating into three-dimensional frameworks with an open 1D channel along the a axis. 1 and 2 display extensive and excellent solvent stability. Magnetic studies of 1 and 2 indicate that they exhibit interesting solvent-dependent magnetization dynamics. Importantly, 1 and 2 can act as highly effective catalysts for the carboxylic cyclization of propargyl alcohols with carbon dioxide (CO2) under ambient operating conditions. Additionally, the substrate scope was further explored over compound 1 based on the optimal conditions, and it exhibits efficient cyclic carboxylation of various terminal propargylic alcohols with CO2. This research offers an effective approach for the solvent-guided synthesis of MOFs materials and also presents the great application value of MOFs in CO2 chemical conversion.

Rh(II)-catalyzed formal [3+3] cycloaddition of diazonaphthoquinones and propargyl alcohols: Synthesis of 2,3-dihydronaphtho-1,4-dioxin derivatives

A Rh(II)-catalyzed formal [3+3] cyclization of diazonaphthoquinones and propargyl alcohol is reported to afford 2,3-dihydro-1,4-benzodioxins. Various terminal propargyl alcohols react with diazonapthoquinone in the presence of Rh2(OAc)4 to give the corresponding dihydrodioxins in good to high yields. However, dihydrodioxins are not formed in the reaction of internal propargyl alcohols, and the O–H insertion product and 2,5-dihydrofurans are formed as the main product(s) depending on the terminal substituent. 2,3-Dihydro-1,4-benzodioxins are proposed to be formed via Rh(II)-catalyzed intermolecular oxonium ylide formation and subsequent 6-exo-dig cyclization with the internal alkynyl group.

Gold-Catalyzed Iminations of Terminal Propargyl Alcohols with Anthranils with Atypical Chemoselectivity for C(1)-Additions and 1,2-Carbon Migration.

This work reports gold-catalyzed iminations of terminal propargyl alcohols with anthranils or isoxazoles to yield E-configured α-amino-2-en-1-ones and -1-als with complete chemoselectivity. These catalytic iminations occur exclusively with C(1)-nucleophilic additions on terminal alkynes, in contrast to a typical C(2)-route. For 3,3-dialkylprop-1-yn-3-ols, a methyl substituent is superior to long alkyl chains as the 1,2-migration groups toward α-imino gold carbenes. For secondary prop-1-yn-3-ols, phenyl, vinyl, and cyclopropyl substituents are better than hydrogen as the migrating groups, obviating typical gold carbene reactions. DFT calculations have been performed to rationalize the observed C(1)-regioselectivity and the preferable cyclopropyl migration based on gold carbene pathways.

Copper(i) iodide cluster-based lanthanide organic frameworks: synthesis and application as efficient catalysts for carboxylative cyclization of propargyl alcohols with CO2 under mild conditions.

Two metal-organic frameworks (MOFs), namely, [Dy2Cu4I4(NA)6(DMF)2]n (1) and [Gd2Cu2I2(IN)6(DMF)4]·5DMF (2) (HNA = nicotinic acid, HIN = isonicotinic acid), constructed based on lanthanide ions and copper iodide clusters ([Cu4I4] and [Cu2I2]) were successfully synthesized and characterized. Compound 1 has a three-dimensional framework and compound 2 displays a two-dimensional plane with sql topology, respectively. Both of them exhibit high thermostability and solvent stabilities. Additionally, catalytic explorations reveal that 1 displays higher catalytic activity than 2 for the carboxylic cyclization of propargyl alcohols. More importantly, 1 also exhibits excellent catalytic performance in the carboxylation reactions of CO2 and terminal propargylic alcohols with various substituents. To the best of our knowledge, this is the first example of non-noble metal based MOF catalysts for the carboxylative cyclization of propargyl alcohols with CO2 under atmospheric pressure and at room temperature, which provides a highly promising approach for MOFs in the catalytic conversion of CO2 to valuable chemicals.

Upgrading CO2 by Incorporation into Urethanes through Silver‐Catalyzed One‐Pot Stepwise Amidation Reaction

One‐pot two‐step stepwise reaction of terminal propargylic alcohols, carbon dioxide, and primary/secondary amines for the effective synthesis of various urethanes through robust silver‐catalysed C‐O/C‐N bond formation is reported. Catalytic activities were investigated by controlling catalyst loading, reaction pressure and time, and very high turnover number (turnover frequency) was obtained: 3350 (35 h−1) with 0.01 mol% silver catalyst under 0.1 MPa, and up to 13360 (139 h−1) with 0.005 mol% silver catalyst under 2.0 MPa at room temperature. The strategy was ingeniously regulated, and synchronously afforded a wide range of β‐oxopropylcarbamate and 1,3‐oxazolidin‐2‐one motifs in excellent yields and selectivity together with unprecedented high turnover number (TON) and turnover frequency (TOF) value.

Metal-Catalyzed Intra- and Intermolecular Addition of Carboxylic Acids to Alkynes in Aqueous Media: A Review

The metal-catalyzed addition of carboxylic acids to alkynes is a very effective tool for the synthesis of carboxylate-functionalized olefinic compounds in an atom-economical manner. Thus, a large variety of synthetically useful lactones and enol-esters can be accessed through the intra- or intermolecular versions of this process. In order to reduce the environmental impact of these reactions, considerable efforts have been devoted in recent years to the development of catalytic systems able to operate in aqueous media, which represent a real challenge taking into account the tendency of alkynes to undergo hydration in the presence of transition metals. Despite this, different Pd, Pt, Au, Cu and Ru catalysts capable of promoting the intra- and intermolecular addition of carboxylic acids to alkynes in a selective manner in aqueous environments have appeared in the literature. In this review article, an overview of this chemistry is provided. The synthesis of β-oxo esters by catalytic addition of carboxylic acids to terminal propargylic alcohols in water is also discussed.

AgI /TMG-Promoted Cascade Reaction of Propargyl Alcohols, Carbon Dioxide, and 2-Aminoethanols to 2-Oxazolidinones.

Chemical valorization of CO2 to access various value-added compounds has been a long-term and challenging objective from the viewpoint of sustainable chemistry. Herein, a one-pot three-component reaction of terminal propargyl alcohols, CO2 , and 2-aminoethanols was developed for the synthesis of 2-oxazolidinones and an equal amount of α-hydroxyl ketones promoted by Ag2 O/TMG (1,1,3,3-tetramethylguanidine) with a TON (turnover number) of up to 1260. By addition of terminal propargyl alcohol, the thermodynamic disadvantage of the conventional 2-aminoethanol/CO2 coupling was ameliorated. Mechanistic investigations including control experiments, DFT calculation, kinetic and NMR studies suggest that the reaction proceeds through a cascade pathway and TMG could activate propargyl alcohol and 2-aminoethanol through the formation of hydrogen bonds and also activate CO2 .

(para‐Cymene)Ru(dppp)Cl][PF6]‐Catalysed Stereospecific Synthesis of O‐Dienyl Esters, and Evaluation of the Anticancer Activity of a Long‐Chain Fatty Acid O‐Dienyl Ester

O‐Dienyl esters are obtained through the regio‐ and stereospecific addition of both aromatic and aliphatic carboxylic acids to terminal propargylic alcohols, with the sequential formation of a carbon–oxygen bond and dehydration, in the presence of [(p‐cymene)Ru(dppp)Cl][PF6] (1). Also, the cytotoxicity and anticancer activity of the newly synthesized O‐dienyl ester (Z)‐3‐methylbuta‐1,3‐dienyl oleate have been investigated.

Silver(I)-Promoted Cascade Reaction of Propargylic Alcohols, Carbon Dioxide, and Vicinal Diols: Thermodynamically Favorable Route to Cyclic Carbonates.

A silver(I)-promoted cascade reaction was developed for the synthesis of cyclic carbonates from terminal propargylic alcohols, carbon dioxide, and vicinal diols. Compared with direct condensation of vicinal diols with CO2, this protocol provides a thermodynamically favorable route to cyclic carbonates and α-hydroxyl ketones in excellent yields (up to 97%) without the additional dehydration step. Such a cascade procedure proceeds presumably through initial reaction of propargylic alcohol with CO2 and subsequent nucleophilic attack of vicinal alcohol on in situ-formed α-alkylidene cyclic carbonate, resulting in successive generation of α-alkylidene cyclic carbonate, unsymmetrical β-oxoalkyl carbonate, cyclic carbonate, and α-hydroxyl ketone.

ChemInform Abstract: Silver(I)‐Catalyzed Three‐Component Reaction of Propargylic Alcohols, Carbon Dioxide and Monohydric Alcohols: Thermodynamically Feasible Access to β‐Oxopropyl Carbonates.

AbstractThe procedure affords various title compounds in mostly high yields, if terminal propargylic alcohols are used.

A Trialkylphosphine-Derived Palladacycle as a Catalyst in the Selective Cross-Dimerization of Terminal Arylacetylenes with Terminal Propargyl Alcohols and Amides

A method for the selective cross-dimerization of terminal aryl alkynes with propargyl alcohols to afford linear (E)-enynol products is reported. The complex [Pd(μ-κ2-O,O-OAc)(κ2-C,P-(t-Bu)2PCH2C(Me)2CH2)]2 selectively affords (E)-5-aryl-2-en-4-yn-1-ol products in good yields under mild conditions with high chemo-, regio-, and stereoselectivity. In contrast, previously reported examples of this reaction afford the branched 4-aryl-2-hydroxymethanol-1-buten-3-yne. Propargyl amides are also selectively cross-dimerized, but with lower regioselectivity for the linear enyne. The method has been applied to the synthesis of (E)-5-phenyl-2-penten-4-yn-1ol, which is a precursor to type 2 diabetes drug candidate NNC 61-4655, in 72% yield from phenylacetylene and propargyl alcohol. The palladacycle precatalyst reacts with aryl alkynes to afford the first example of a dimeric palladacycle complex with a μ-κ2-C1,C1-bound acetylide ligand. This complex is observed during the catalytic reaction and is a competent precatalyst.

Thermodynamically Favorable Synthesis of 2-Oxazolidinones through Silver-Catalyzed Reaction of Propargylic Alcohols, CO2, and 2-Aminoethanols.

Development of catalytic routes to incorporate CO2 into carbonyl compounds at mild conditions remains attractive and challenging. Herein, a one-pot three-component cascade reaction of terminal propargylic alcohols, CO2 , and 2-aminoethanols through Ag(I) -based catalysis is reported for the synthesis of carbonyl compounds through C-O/C-N bond formation. This thermodynamically favorable route can be ingeniously regulated to afford a wide range of 2-oxazolidinones along with concurrent production of α-hydroxyl ketone derivatives in excellent yields and selectivity. Preliminary mechanistic studies indicate that such a process proceeds through successive formation of α-alkylidene cyclic carbonate, β-oxopropylcarbamate, and 2-oxazolidinones.

Ruthenium Complex‐Catalyzed Domino Addition/exo‐ Cycloisomerization of Propargylic Alcohols and Tosyl Isocyanate to Form Oxazolidinones

AbstractA ruthenium complex with a tetradentate nitrogen–phosphorus mixed ligand is shown to be an efficient catalyst for domino addition/exo‐cycloisomerization of propargylic alcohols and tosyl isocyanate. In the presence of 2–5 mol% ruthenium complex, a range of terminal propargylic alcohols were reacted with tosyl isocyanate to furnish the corresponding oxazolidinone product exclusively in moderate to excellent yields. Mechanistic studies suggest that propargylic alcohol and tosyl isocyanate undergo addition firstly to generate propargylic carbamate, which is then activated by the ruthenium complex to form an η2‐alkyne complex, rather than the ruthenium vinylidene intermediate, to afford the final oxazolidinone product.magnified image

Copper(I)‐Catalyzed Three‐Component Reaction of Terminal Propargyl Alcohols, Aldehydes, and Amines: Synthesis of 3‐Amino‐2‐pyrones and 2,5‐Dihydrofurans

AbstractA novel copper(I)‐catalyzed three‐component reaction for the efficient synthesis of 3‐amino‐2‐pyrones and 2,5‐dihydrofurans from propargyl alcohols, aldehydes, and amines has been developed. The starting materials are easily available and the scope of this method is broad. Through mechanistic studies, it is believed that the three‐component reaction consists of an A3‐coupling to propargylic amine, alkyne–allene isomerization, and intramolecular cyclization of the allenol to form a furan. In case of using ethyl glyoxalate as the aldehyde, a ring‐opening, lactonization, and isomerization process affords the 3‐amino‐2‐pyrones.

Copper(I)-catalyzed three-component reaction of terminal propargyl alcohols, aldehydes, and amines: synthesis of 3-amino-2-pyrones and 2,5-dihydrofurans.

A novel copper(I)-catalyzed three-component reaction for the efficient synthesis of 3-amino-2-pyrones and 2,5-dihydrofurans from propargyl alcohols, aldehydes, and amines has been developed. The starting materials are easily available and the scope of this method is broad. Through mechanistic studies, it is believed that the three-component reaction consists of an A(3) -coupling to propargylic amine, alkyne-allene isomerization, and intramolecular cyclization of the allenol to form a furan. In case of using ethyl glyoxalate as the aldehyde, a ring-opening, lactonization, and isomerization process affords the 3-amino-2-pyrones.

ChemInform Abstract: Tandem Pd/Au‐Catalyzed Route to α‐Sulfenylated Carbonyl Compounds from Terminal Propargylic Alcohols and Thiols.

AbstractThe reaction is proposed to proceed through a Pd‐catalyzed regioselective hydrothiolation at the terminal triple bond followed by an Au‐catalyzed 1,2‐hydride migration.

Tandem Pd/Au‐Catalyzed Route to α‐Sulfenylated Carbonyl Compounds from Terminal Propargylic Alcohols and Thiols

An efficient and highly atom-economical tandem Pd/Au-catalyzed route to α-sulfenylated carbonyl compounds from terminal propargylic alcohols and thiols has been developed. This one-step procedure has a wide substrate scope with respect to substituents at the α-position of the alcohol. Both aromatic and aliphatic thiols generated the α-sulfenylated carbonyl products in good to excellent yields. A mechanism is proposed in which the reaction proceeds through a Pd-catalyzed regioselective hydrothiolation at the terminal triple bond of the propargyl alcohol followed by an Au-catalyzed 1,2-hydride migration.

ChemInform Abstract: Rhodium‐Catalyzed Chemo‐ and Regioselective Cross‐Dimerization of Two Terminal Alkynes.

AbstractDimerization of terminal acetylenes and terminal propargylic alcohols, ethers, and amides results mostly in the formation of two isomers favouring the head‐to‐tail derivatives.

Synthesis and Reactivity of New Rhenium(I) Complexes Containing Iminophosphorane-Phosphine Ligands: Application to the Catalytic Isomerization of Propargylic Alcohols in Ionic Liquids

[ReBr(CO)5] reacts with the iminophosphorane-phosphine ligands Ph2PCH2P(═NR)Ph2 (R = P(═O)(OEt)2 (1a), P(═O)(OPh)2 (1b), P(═S)(OEt)2 (1c), P(═S)(OPh)2 (1d), 4-C6F4CHO (1e), 4-C6F4CN (1f), 4-C5F4N (1g)) affording the neutral complexes [ReBr(κ(2)-P,X-Ph2PCH2P{═NP(═X)(OR)2}Ph2)(CO)3] (X = O, R = Et (2a), Ph (2b); X = S, R = Et (2c), Ph (2d)) and [ReBr{κ(2)-P,N-Ph2PCH2P(═NR)Ph2}(CO)3] (R = P(═O)(OEt)2 (3a), P(═O)(OPh)2 (3b), 4-C6F4CHO (3e), 4-C6F4CN (3f), 4-C5F4N (3g)). The reactivity of the cationic complex [Re(κ(3)-P,N,S-Ph2PCH2P{═NP(═S)(OPh)2}Ph2)(CO)3][SbF6] (4d) has been explored allowing the synthesis of the cationic [Re(L)(κ(2)-P,S-Ph2PCH2P{═NP(═S)(OPh)2}Ph2)(CO)3][SbF6] (L = acetone (5a), CH3C≡N (5b), pyridine (5c), PPh3 (5d)) and the neutral [ReY(κ(2)-P,S-Ph2PCH2P{═NP(═S)(OPh)2}Ph2)(CO)3] (Y = Cl (6a), I (6b), N3 (6c)) complexes. The catalytic activity of complex 4d in the regioselective isomerization of terminal propargylic alcohols HC≡CCR(1)R(2)(OH) into α,β-unsaturated aldehydes R(1)R(2)C═CHCHO or ketones R(3)R(4)C═CR(1)COMe (if R(2) = CHR(3)R(4)) under neutral conditions in ionic liquids has being studied. Isolation and X-ray characterization of the key intermediate rhenium(I) oxocyclocarbene complex [Re{═C(CH2)3O}(κ(2)-P,S-Ph2PCH2P{═NP(═S)(OPh)2}Ph2)(CO)3][SbF6] (5e) seems to indicate that the catalytic reaction proceeds through tautomerization of the terminal alkynols to yield vinilydene-type species.