Hydration Of Alkynes Research Articles

Assessment of DFT methods for computing activation energies of Mo/W-mediated reactions.

Using high level ab initio coupled cluster calculations as reference, the performances of 15 commonly used density functionals (DFs) on activation energy calculations for typical Mo/W-mediated reactions have been systematically assessed for the first time in this work. The selected representative Mo/W-mediated reactions cover a wide range from enzymatic reactions to organometallic reactions, which include Mo-catalyzed aldehyde oxidation (aldehyde oxidoreductase), Mo-catalyzed dimethyl sulfoxide (DMSO) reduction (DMSO reductase), W-catalyzed acetylene hydration (acetylene hydratase), Mo/W-mediated olefin metathesis, Mo/W-mediated olefin epoxidation, W-mediated alkyne metathesis, and W-mediated C-H bond activation. Covering both Mo- and W-mediated reactions, four DFs of B2GP-PLYP, M06, B2-PLYP, and B3LYP are uniformly recommended with and without DFT empirical dispersion correction. Among these four DFs, B3LYP is notably improved in performance by DFT empirical dispersion correction. In addition to the absolute value of calculation error, if the trend of DFT results is also a consideration, B2GP-PLYP, B2-PLYP, and M06 keep better performance than other functionals tested and constitute our final recommendation of DFs for both Mo- and W-mediated reactions.

Substrate‐Mediated Deactivation of a Ru(PtBu2NBn2) Cooperative Complex

AbstractLigand design for metal–ligand cooperative (MLC) catalysis is inherently more complex than that for traditional non‐cooperative ligands. The basicity, sterics and structure of the acid/base group in MLC proton‐transfer (PT) complexes, for instance, undoubtedly influence catalyst performance. Herein, we evaluate the highly tunable PR2NR′2 (1,5‐R′‐3,7‐R‐1,5‐diaza‐3,7‐diphosphacyclooctane) ligand family for the first time in an organic transformation. With [Ru(Cp)(PtBu2NBn2)(MeCN)][PF6] as the catalyst, no turnover was observed in the anti‐Markovnikov hydration of alkynes, a known PT MLC reaction. Treatment of the cooperative complex with phenylacetylene affords a vinylammonium product in which the pendant nitrogen atom of the PtBu2NBn2 ligand forms a Lewis acid–base adduct with the alpha‐carbon atom of the vinylidene intermediate. Characterization by X‐ray crystallography and NMR spectroscopy conclusively assign this structure in both the solid and the solution state. The adduct formation is irreversible, and the adduct is characterized as a catalyst deactivation product.

ChemInform Abstract: Regioselective Hydration of Terminal Alkynes Catalyzed by a Neutral Gold(I) Complex [(IPr)AuCl] and One‐Pot Synthesis of Optically Active Secondary Alcohols from Terminal Alkynes by the Combination of [(IPr)AuCl] and Cp*RhCl[(R,R)‐TsDPEN

A neutral gold(I) complex [(IPr)AuCl] (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene) was found to be a highly effective catalyst for the hydration of terminal alkynes, including aromatic alkynes and aliphatic alkynes. The desired methyl ketones were obtained in high yields with complete regioselectivities. Furthermore, a series of optically active secondary alcohols could be obtained in high yield with good to excellent enatioselectivities via one-pot sequential hydration/asymmetric transfer hydrogenation (ATH) from terminal alkynes by the combination of of [(IPr)AuCl] and Cp*RhCl[(R,R)-TsDPEN] (Cp* = pentamethylcyclopentadienyl, TsDPEN = N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine). Notably, this research exhibited the potential of the direct use of neutral gold(I) complexes instead of cationic ones as catalysts for the activation of multiple bonds for organic synthesis.

Solvent-free hydration of alkynes over Hβ zeolite

An efficient and environmentally benign catalytic system has been successfully developed for highly Markovnikov selective hydration of various alkynes over heterogeneous catalyst (Hβ zeolite) in solvent-free conditions. The catalyst (Hβ zeolite) is commercial available, recyclable and exhibits excellent catalytic activity towards the hydration of alkynes to ketones. Moreover, the propargylic aryl carbinols undergo Meyer–Schuster rearrangement to give α,β-unsaturated carbonyl compounds in excellent yields.

Amide Oxygen-Assisted Palladium-Catalyzed Hydration of Alkynes.

Herein, an amide oxygen-assisted palladium-catalyzed hydration reaction of alkynes is realized to prepare a series of o-acylacetanilide derivatives with high yield, and single regioselectivity under mild reaction conditions. This transformation is simple, practical, and can be performed on a gram scale. Evaluation of the mechanism shows that the reaction should involve an oxypalladation process, and the 1,3-oxazine compound is proven to be a key intermediate.

ChemInform Abstract: Copper‐Catalyzed Markovnikov Hydration of Alkynes.

Conventional, highly efficient, inexpensive copper triflate catalyzed regioselective Markovnikov hydration of terminal and internal alkynes have been reported. Significant shorter reaction time and excellent yield without addition of additive make the method attractive. Effects of catalyst and solvent on the hydration reaction have also been studied.

Hydrogen-bonding pincer complexes with two protic N-heterocyclic carbenes from direct metalation of a 1,8-bis(imidazol-1-yl)carbazole by platinum, palladium, and nickel.

Pincer protic N-heterocyclic carbene (PNHC) complexes were synthesized by direct metalation, the formation of a metal carbon bond from an unfunctionalized CH bond in a single synthetic step. Significantly, direct metalation succeeded even for a first-row metal, nickel. The chloride complexes were isolated and then converted to the acetate, triflate, or in the platinum case, a hydride analogue. Crystal structures and (1) H, (13) C, and (15) N NMR data, as well as IR spectra, document the effects of intramolecular hydrogen bonding and the planar but flexible pincer framework. Anti-Markovnikov addition of OH bonds to alkynes, including catalyzed alkyne hydration, were demonstrated on the Pt triflate analog.

ChemInform Abstract: Regioselectivity in the Au‐Catalyzed Hydration and Hydroalkoxylation of Alkynes

AbstractReview: [51 refs.

ChemInform Abstract: Efficient Hydration of Alkynes Through Acid‐Assisted Broensted Acid Catalysis.

AbstractThe combined acid catalyzed hydration of alkynes is an efficient one‐step synthesis of carbonyl compounds.

SnCl4·5H2O: A Highly Efficient Catalyst for Hydration of Alkyne

SnCl4·5H2O is a highly efficient catalyst in the hydration of terminal alkynes that affords carbonyl compounds in high to good yields. Under the optimized reaction conditions, the moderate to excellent yields of corresponding ketones were obtained when the aromatic and aliphatic terminal alkynes were used as substrates. With using diphenylacetylene as an internal alkyne, the corresponding ketone was not detected in the reaction mixture.

ChemInform Abstract: Supported Gold Nanoparticle‐Catalyzed Hydration of Alkynes under Basic Conditions.

AbstractThe title reaction proceeds under weakly basic conditions and is compatible with acid‐sensitive functional groups.

ChemInform Abstract: Hydration of Alkynes at Room Temperature Catalyzed by Gold(I) Isocyanide Compounds.

AbstractTitle hydration process affords a variety of ketones [(II) or (IV), resp.] under mild reaction conditions in a simple one‐step procedure.

Hydration of Alkynes with Au/TiO2 in the Presence of Morpholine

Key words gold nanoparticles - titanium dioxide - hydration - alkynes

Regioselective hydration of terminal alkynes catalyzed by a neutral gold(I) complex [(IPr)AuCl] and one-pot synthesis of optically active secondary alcohols from terminal alkynes by the combination of [(IPr)AuCl] and Cp*RhCl[(R,R)-TsDPEN

A neutral gold(I) complex [(IPr)AuCl] (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene) was found to be a highly effective catalyst for the hydration of terminal alkynes, including aromatic alkynes and aliphatic alkynes. The desired methyl ketones were obtained in high yields with complete regioselectivities. Furthermore, a series of optically active secondary alcohols could be obtained in high yield with good to excellent enatioselectivities via one-pot sequential hydration/asymmetric transfer hydrogenation (ATH) from terminal alkynes by the combination of of [(IPr)AuCl] and Cp*RhCl[(R,R)-TsDPEN] (Cp* = pentamethylcyclopentadienyl, TsDPEN = N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine). Notably, this research exhibited the potential of the direct use of neutral gold(I) complexes instead of cationic ones as catalysts for the activation of multiple bonds for organic synthesis.

Copper-catalyzed Markovnikov hydration of alkynes

Conventional, highly efficient, inexpensive copper triflate catalyzed regioselective Markovnikov hydration of terminal and internal alkynes have been reported. Significant shorter reaction time and excellent yield without addition of additive make the method attractive. Effects of catalyst and solvent on the hydration reaction have also been studied.

Catalytic hydration of alkynes to ketones by a salen–gold(III) complex

A general atom-economical approach for the synthesis of ketones is demonstrated through hydration of a wide range of alkynes catalyzed by a salen–gold(III) complex in the presence of trifluoroacetic acid as the cocatalyst. Various terminal and internal alkynes were suitable substrates for the catalytic system.

ChemInform Abstract: One‐Pot Sequential Catalytic Hydration of Alkynes and α‐Alkylation with Alcohols for the Synthesis of α‐Alkylated Ketones

Abstract29 examples

Hydration of alkynes at room temperature catalyzed by gold(i) isocyanide compounds

Gold(i) isocyanide shows high catalytic ability for the hydration of different alkynes at room temperature.

Regioselectivity in the Au-catalyzed hydration and hydroalkoxylation of alkynes.

Over the past decade and a half, homogenous gold catalysis has emerged as a diverse and rich field of research resulting in the continuous development of new methods for organic synthesis. The activation of alkynes towards nucleophilic attack by Au(I) and Au(III) complexes is a well-established mode of reactivity and the gold-catalyzed hydration and hydroalkoxylation of alkynes are two of the more well-explored reaction pathways. Although these classes of reactions have seen continuous development since their initial reports, achieving regioselectivity persists as one of the most challenging issues for this chemistry. This article aims to draw attention to the general problem of regioselectivity in these reactions. A select set of examples is presented to highlight the challenges and survey some of the strategies employed to address this problem.

Efficient hydration of alkynes through acid-assisted Brønsted acid catalysis.

The combined acid catalyzed hydration of alkynes is an efficient one-step synthesis of carbonyl compounds. This atom-economical method is effective with a wide range of substrates, and the products are obtained in very good yields with low catalyst loading (0.2%). Furthermore, solid acids like Nafion were also efficient and could be easily recycled multiple times without loss of reactivity.