Propargylic Alcohols Research Articles

Total Synthesis of the Guangnanmycin A Alcohol.

Guangnanmycin A is a recently discovered congener of the well-known antitumor drug lead leinamycin; its macrolactam ring, however, is even more strained than that of the parent compound. The first synthetic foray towards this challenging target is reported, which relies on molybdenum-catalyzed macrocyclization by ring closing alkyne metathesis (RCAM) followed by ruthenium-catalyzed redox isomerization of the propargyl alcohol thus formed; the resulting enone enabled the introduction of the yet missing exo-methylene group by a modified Peterson olefination. The signature disulfide moiety of guangnanmycin A was installed by strain-driven thia-Michael addition followed by conversion of the thioether thus formed into an unsymmetric disulfide with the aid of (methylthio)dimethylsulfonium tetrafluoroborate and MeSSMe. While this sequence furnished racemic guangnanmycin A alcohol in good overall yield, the final oxidation to the corresponding acid failed, most likely because of the exceptional sensitivity of the strained scaffold.

Silver Metal-Organic Framework Derived N-Doped Carbon Nanofibers for CO2 Conversion into β-Oxopropylcarbamates.

Developing efficient heterogeneous catalysts for chemical fixation of CO2 to produce high-value-added chemicals under mild conditions is highly desired but still challenging. Herein, we first reported an approach to prepare a novel catalyst (Ag@NCNFs), featuring Ag nanoparticles (NPs) embedded within porous nitrogen-doped carbon nanofibers (NCNFs), via growing a Ag metal-organic framework on one-dimensional electrospun nanofibers followed by pyrolysis. Benefiting from the abundant nitrogen species and porous structure, Ag NPs is well dispersed in the obtained Ag@NCNFs. Catalytic studies indicated that Ag@NCNFs exhibited excellent catalytic activity for the three-component coupling reaction of CO2, secondary amines, and propargylic alcohols to generate β-oxopropylcarbamates under mild conditions with a turnover number (TON) of 16.2, and it can be recycled and reused at least 5 times without an obvious decline in catalytic activity. The reaction mechanism was clearly clarified by FTIR, NMR, 13C isotope labeling, control experiments, and density functional theory calculations. The results suggest that Ag@NCNFs and 1,8-diazabicyclo[5.4.0]undec-7-ene can synergistically activate propargylic alcohol to react with CO2, and then the generated α-alkylidene cyclic carbonate was invaded by secondary amine to produce β-oxopropylcarbamate. Importantly, to the best of our knowledge, this is the first experimental and theoretical investigation on this reaction.

Kinetic Resolution of Acyclic Tertiary Propargylic Alcohols by NHC-Catalyzed Enantioselective Acylation.

We report herein an efficient NHC-catalyzed kinetic resolution of acyclic tertiary propargylic alcohols that provides them in high to excellent enantioselectivity. This is the first example of kinetic resolution realized by enantioselective acylation. The recovered enantioenriched alcohols can be facilely converted into other valuable compounds such as densely functionalized tertiary alcohols and carbmates in high yields and excellent stereopurity. Density functional theory calculations were performed to determine the reaction mechanism and to understand the origin of enantiodiscrimination.

CHEMICAL REMOVAL OF IRON SULFIDE DEPOSIT IN PIPES FROM OIL AND SOUR GAS PRODUCTION

Hydrogen sulfide (H2S) and carbon dioxide (CO2) present in oil and natural gas cause mild steel corrosion, potentially resulting in formation of corrosion product layers on the internal surfaces of tubulars. In field experiences relating to the research reported herein, this has led to restrictions on the flow of water produced from a three-phase horizontal separator. This paper demonstrates a specific case of chemical removal of relatively hard, dark, and adherent heterogeneous deposits on the internal surface of the pipe. The phases involved in this process are iron sulfide, iron oxides and calcium carbonate existing as scales/corrosion products. To evaluate their dissolution, laboratory tests were conducted using hydrochloric acid (HCl) with additions of chlorine in the form of calcium hypochlorite [Ca(ClO)2]. Appropriate safety measures were taken employed, considering hazards associated with chlorine and toxicity of hydrogen sulfide. The treatment regime had 87 % effectiveness for scale removal in combination with propargyl alcohol (2-propyn-1-ol) as a corrosion inhibitor.

Propargyl alcohol as an acrolein equivalent: synthesis of β-(3-indolyl)acroleins and β-(imidazo[1,2-a]pyridin-3-yl)acroleins.

A simple and straightforward method has been developed to access distinctly substituted β-(3-indolyl)acroleins and β-(imidazo[1,2-a]pyridin-3-yl)acroleins using propargyl alcohol as an acrolein equivalent. A broad substrate scope, good yields, easily accessible substrates, and metal-free conditions are the salient features of the developed methodology. This work contributes to a significant advancement in the sustainable synthesis of functionalized acroleins.

Utilizing perhalopyridine-based alkynes as suitable precursors for the synthesis of novel poly(1,2,3-triazolyl)-substituted perhalopyridines.

A novel series of poly(1,2,3-triazolyl)-substituted perhalopyridines 5a-f were successfully synthesized from the click reaction of the terminal alkynes (drived from the nucleophilic substitution reactions of PFP 1a and PCP 1b with excess amounts of propargyl alcohol) with aryl azides 4a-c under ultrasonic irradiation. Likewise, the sonication of reaction mixtures containing pyridyl cores 3, alkyl bromides 6a,b, and NaN3 under one-pot conditions afforded their respective aliphatic 1,2,3-triazoles 7a-d in yields ranging from 71% to 83%. We next developed an effective method for the regioselective preparation of 2,3,4,5-tetrachloro-6-(prop-2-yn-1-yloxy)pyridine 3c through SNAr reaction of PCP with propargyl alcohol without the utilization of any catalyst. It was then used to fabricate several ((1,2,3-triazol-4-yl)methoxy)-3,4,5,6-tetrachloropyridines 8a-c under the reaction conditions. Finally, the Pd(PPh3)4-catalyzed SMC reaction of tris-triazoles 5b,e with arylboronic acids 9a-c offered a practical method for the synthesis of biaryl-embedded poly(1,2,3-triazoles) 10a-f in good yields.

Facile access to trifluoromethyl propargyl alcohol by metal-free transfer hydrogenation and cyanation of alkynyl ketones.

We report an efficient synthetic route to the metal-free hydroboration and cyanosilylation of a wide range of alkynyl trifluoromethyl ketones using pinacolborane (4,4,5,5-tetramethyl-1,3,2-dioxaborolane) and trimethylsilyl cyanide under mild reaction conditions at ambient temperature. These highly effective hydroboration and cyanosilylation reactions lead to the corresponding alkynyl trifluoromethyl propargyl alcohols after hydrolysis. In addition, trifluoromethyl (CF3) group-based pharmaceutically active enflicoxib analogs were synthesized from propargyl alcohol.

Synthesis of α-sulfenylated carbonyl compounds under metal-free conditions.

An efficient synthesis of α-sulfenylated carbonyl compounds from propargylic alcohols and aryl thiols under heating conditions is described. The method is characterized by mild conditions, simple operation, metal-free catalysis and good functional group tolerance. Mechanistic studies suggest that the reaction involves a radical pathway and an isomerization process.

Synthesis of Benzochromenes via Brønsted Acid Catalyzed Annulation of Naphthol with Propargyl Alcohols

Synthesis of Benzochromenes via Brønsted Acid Catalyzed Annulation of Naphthol with Propargyl Alcohols

Oxidative Cyclization of Oximes with Propargyl Alcohols toward Functionalized Isoquinoline N‐Oxides Synthesis

AbstractAn efficient and regioselective synthesis of various functionalized isoquinoline N‐oxides has been realized by Rh(III)‐catalyzed oxidative annulation of aryl oximes with tertiary propargyl alcohols. The current protocol features readily available starting materials, mild reaction conditions, broad substrate scope and wide functional group tolerance.

Organocatalytic enantioselective (4+3) cyclization for the synthesis of spiro-fused heterocyclic compounds containing isoindolinone, oxepine and indole moieties.

A refined strategy has been developed to control the regioselective asymmetric (4+3) cyclization of α-(3-isoindolinonyl) propargylic alcohols with 2-indolylmethanols, utilizing chiral phosphoric acid catalysis. This innovative organocatalytic cyclization yields spiro isoindolinone-oxepine-fused indoles featuring a spiro-quaternary stereocenter in high yields and enantioselectivities, facilitated by the solvent of 1,1-dichloro-1-fluoroethane and the additive of hexafluoroisopropanol. Additionally, the photophysical properties of product 3k are examined, revealing bright fluorescence both in the solution and the solid state.

Organocatalytic asymmetric cascade bicyclization: access to chiral polycyclic bisindoles from 2-indolylmethanols and propargylic alcohols

A chiral phosphoric acid-catalyzed asymmetric bis-cyclization of α-indolyl propargylic alcohols with 2-indolylmethanols was realized.

Organocatalyzed double dearomatization reaction of non-functionalized phenols and propargylic alcohols: the important regulating effect of steric hindrance

Steric hindrance-regulated double dearomatization reaction of non-functionalized phenols and propargylic alcohols for the efficient synthesis of polycyclic diketones is reported.

Reaction mechanism of the ethynylation of formaldehyde on copper terminated Cu2O(100) surfaces: a DFT study.

1,4-Butanediol (BDO) is an important chemical raw material for a series of high-value-added products. And the ethynylation of formaldehyde is the key step for the production of BDO by the Reppe process. However, little work has been done to reveal the reaction mechanism. In this work, the reaction mechanism for the ethynylation of formaldehyde process on copper-terminated Cu2O(100) surfaces was investigated with density functional theory (DFT). The reaction network of the ethynylation of formaldehyde was constructed first and the adsorption properties of the related species were calculated. Then the energy barrier and reaction energy of the related reactions and the geometric configuration were calculated. It is a consecutive reaction including two processes. For the propargyl alcohol (PA) formation process, the most favorable pathway is the direct addition of acetylene to formaldehyde followed by a hydrogen transfer reaction. And the rate control step is the hydrogen transfer reaction with an energy barrier of 1.43 eV. For the 1,4-butynediol (BYD) formation process, the most competitive pathway is the addition of PA to CH2OH, including formaldehyde hydrogenation to form CH2OH, coupling addition, and dehydrogenation reaction. The rate control step of this pathway is the dehydrogenation reaction with an energy barrier of 1.51 eV.

The effect of various factors on the yield of 2,3,3–triiode propene–2–ol–1

A triode derivative of propargyl alcohol has been synthesized, and the effects of catalyst concentration, time and temperature on the synthesis process have been studied. Various concentrations of alkalis (5,0–30,0 mass. %) have been used as catalysts. It has been found that 2,3,3–triode propene–2–ol–1 has a higher yield when the concentration of the catalyst NaOH is 15%. The effect of time duration (1–5 hours) on product productivity has also been studied. Product yield has been found to be high for 3 hours. In addition, the effect of temperature on the product’s productivity has also been studied at intervals of (10–60°C). It has been found that the yield of 2,3,3–triiodpropen–2–ol–1 was high in 3 hours at 20°C. The structure of the synthesized substance was studied and confirmed by the methods of IR– and NMR–spectroscopic analysis.

Pd((R)-DTBM-SEGphos)Cl2-catalyzed kinetic resolution of tertiary propargylic alcohols

A variety of optically active tertiary propargylic alcohols and tetrasubstituted 2,3-allenoic acids have been synthesized via a Pd((R)-DTBM-SEGphos)Cl2-catalyzed carboxylative kinetic resolution reaction of racemic tertiary propargylic alcohols.

Synthesis of 2-acyl benzofurans and indoles based on nucleophile-intercepted Meyer–Schuster rearrangement of o-hydroxyphenyl and o-aminophenyl propargylic alcohols

A new type of nucleophile-intercepted Meyer–Schuster rearrangement mediated by pyridine N-oxide under metal-free conditions using a catalytic amount of acid is disclosed. It enables synthesis of 2-acyl benzofurans and indoles in 56–>99% yields.

Integrated synthesis of 3,4-carbazoquinone alkaloids N-Me-carbazoquinocin A, B and D-F.

Carbazole alkaloids carbazoquinocin A-F possessing a 1-alkyl-2-methyl-3,4-ortho-carabazoquinone framework were isolated from the microorganism Streptomyces violaceus 2448-SVT2 in 1995. Furthermore, they were found to exhibit strong inhibitory activity against lipid peroxidation. Herein, we report the integrated synthesis of N-Me-analogues of 5 members of the carbazoquinocin family of natural products, namely, N-Me-carbazoquinocin A, B and D-F. We employed an acid-catalyzed, intramolecular benzannulation of indole-appended Z-enoate propargylic alcohols, which was developed earlier in our laboratory, for the construction of the required carbazole framework. All five natural products were obtained in an overall yield of 50-60%, starting from a commercially available indole.

The role of halide ions in the carboxylative cyclization of propargyl alcohol with CO2 on CuX-deposited UiO-67(bpy) MOFs (X = F, Cl, Br, and I): a DFT study

The synergy between Cu(i) acidity in deposited Cu–halides and DBU is crucial for converting C3H4O and CO2 into cyclic carbonate. DBU activates the hydroxyl group, while the Cu(i) cation is responsible for activating the alkyne bond of C3H4O.

Asymmetric Ruthenium‐Catalyzed C−H Activation by a Versatile Chiral‐Amide‐Directing Strategy

AbstractA versatile and readily available chiral amide directing group has been developed for the ruthenium(II)‐catalyzed asymmetric C−H activation. Asymmetric C−H activation of the related chiral benzamides with various olefins, aldehydes and propargylic alcohols has been accomplished with high stereoselectivities, affording a series of chiral products including 3,4‐dihydroisocoumarins (up to 96 % ee), isocoumarins (up to 92 % ee), phthalides (up to 99 % ee), chiral bicyclo[2.2.1]heptanes (>20 : 1 dr), 4‐alkylidene‐3,4‐dihydroisocoumarins (up to 97 % ee) and allenes (>20 : 1 dr). Importantly, our methodologies enabled concise syntheses of many biologically active compounds and natural products (e.g., Montroumarin, Cyclosporone E, Cyclosporone Q, Concentricolide, Chuangxinol, and Eleutherol).