Dehydrative Alkylation Research Articles

Dehydrative Alkylation of Phenols with Alcohols via Formation of Triflate.

An efficient synergistic trityl cation ([Ph3C][B(C6F5)4])/triflic anhydride (Tf2O) catalyzed alkylation of phenols with alcohols is reported. Benefiting from the formation of the triflate in situ, cheap and readily available active alcohols can be used as the alkylating reagents, and the reaction proceeds under mild reaction conditions with a broad substrate scope. This protocol enables the synthesis of ortho-selective phenols and 2,4,6-trisubstitued phenols containing three different alkyl groups. tert-Amyl triflate was synthesized, and mechanistic studies support a triflate-mediated alkylation process.

Selective transformation of carbohydrates to 5-ethoxymethylfurfural over tungstophosphoric acid supported on activated carbon derived from orange peel

A series of tungstophosphoric acid supported on activated carbon derived from left-over orange-peel catalysts (TPA/OAC) have been prepared. These catalysts were examined for one-pot catalytic transformation of fructose/glucose to 5-ethoxymethylfurfural. Physico-chemical properties of the catalytic materials were executed by using various characterization methods. Spectroscopic analysis results propose that TPA was finely distributed on the high surface area carbon support with persistent Keggin ion structure. The EMF yield is depended on the content of active component TPA on support and also on the reaction conditions. The catalyst with 25 wt% TPA on OAC presented highest activity towards EMF synthesis from fructose. Although, the catalyst 25 wt% TPA/OAC showed low activity towards EMF synthesis from glucose, higher yields of ethyl glucopyranoside could be formed from glucose in EtOH. Activated carbon was synthesized by carbonization of orange peel treated with H3PO4, which was used as a good support for HPAs. The catalysts are quite stable and recyclable for the dehydrative alkylation of fructose.

Nickel-catalyzed site- and stereoselective reductive alkylalkynylation of alkynes

Nickel-catalyzed site- and stereoselective reductive alkylalkynylation of alkynes

Dehydrative Synthesis of Functionalized Skipped Dienes from Stabilized Phosphonium Ylides and Allylic Alcohols in Water

AbstractA mild and extra activator‐free dehydrative alkylation of stabilized phosphonium ylides with allylic alcohols in water is developed in the presence of [Pd(allyl)Cl]2/dppf catalyst. A wide range of aryl, heteroaryl, alkyl and even allylic tertiary alcohols can readily react with stabilized phosphonium ylides with high regioselectivity for the efficient synthesis of functionalized skipped dienes in moderate to high yields. The role of water was investigated by means of a high‐resolution mass spectrum and diffusion‐ordered spectroscopy nuclear magnetic resonance, and the results revealed that water might play a crucial role in the formation of the π‐allylpalladium complex via hydrogen bond. However, the present method is not suitable for water‐sensitive phosphonium ylides.magnified image

Iron-Catalyzed Dehydrative Alkylation of Propargyl Alcohol with Alkyl Peroxides To Form Substituted 1,3-Enynes.

This paper reports a new method for the generation of substituted 1,3-enynes, whose synthesis by other methods could be a challenge. The dehydrative decarboxylative cascade coupling reaction of propargyl alcohol with alkyl peroxides is enabled by an iron catalyst and alkylating reagents. Primary, secondary, and tertiary alkyl groups can be introduced into 1,3-enynes, affording various substituted 1,3-enynes in moderate to good yields. Mechanistic studies suggest the involvement of a radical-polar crossover pathway.

Efficient dehydrative alkylation of thiols with alcohols catalyzed by alkyl halides.

Alcohols can be efficiently converted into the useful thioethers by a transition metal- and base-free dehydrative S-alkylation reaction with thiols or disulfides by employing alkyl halides as the effective catalyst. This simple and efficient method is a green and practical way for the preparation of thioethers, as it tolerates a wide range of substrates such as aryl and alkyl thiols, as well as benzylic, allylic, secondary, tertiary, and even the less reactive aliphatic alcohols.

ChemInform Abstract: SnBr4‐Promoted Friedel—Crafts Type Dehydrative Alkylation Reaction of Diarylmethanols with 2‐Naphthol Derivatives.

AbstractAn efficient Friedel—Crafts type dehydrative alkylation reaction of diarylmethanols with 2‐naphthols promoted by SnBr4 under mild conditions is developed.

SnBr4-promoted Friedel–Crafts type dehydrative alkylation reaction of diarylmethanols with 2-naphthol derivatives

Tin(IV) bromide was found to act as an efficient Lewis acid catalyst for the Friedel–Crafts type dehydrative alkylation reaction of diarylmethanols with 2-naphthol derivatives under mild conditions. The effects of the substituents on the substrates were systematically evaluated, and the reaction could be applied to a variety of substrates by tuning the conditions depending on the electronic properties of the starting materials.

One-pot sonochemical synthesis of ferrocenyl derivatives via a three-component reaction in aqueous media

An ultrasound-assisted three-component, one-pot domino reaction with ferrocenecarboxaldehyde is herein reported. The sequence of reactions entails the allylindation and dehydrative alkylation of stabilized C-nucleophiles (e.g. electron-rich – (hetero)aromatics and stabilized enols) and N-nucleophiles (e.g. azoles). Sonochemical reactions have been performed in three different high-intensity reactors: a bath (20.3kHz, 60W), as well as two cup horns working at 19.9kHz (75W) and 300.5kHz (70W) giving a library of 18 new ferrocenyl derivatives.

Dehydrative Alkylation of 2-Methylquinoline with Alcohols Using Pt/Al2O3

Dehydrative Alkylation of 2-Methylquinoline with Alcohols Using Pt/Al2O3

ChemInform Abstract: Polymeric Bimetallic Catalyst‐Promoted In‐Water Dehydrative Alkylation of Ammonia and Amines with Alcohols.

AbstractA polymeric heterobimetallic catalyst is prepared by ionic convolution of a poly(catechol borate) and iridium‐NHC complexes.

Polymeric Bimetallic Catalyst-Promoted In-Water Dehydrative Alkylation of Ammonia and Amines with Alcohols

A dehydrative alkylation with three kinds of Ir/B heterobimetallic polymeric catalysts in water is reported. The polymeric heterobimetallic catalysts were readily prepared by ionic convolution of a poly(catechol borate) and iridium complexes. The N-alkylation of ammonia and amines with alcohols, as alkylating agents, was carried out with a heterogeneous catalyst (1 mol% Ir) at 100 °C without the use of organic solvents under aerobic and aqueous conditions to afford the corresponding alkylated amines in high yield.

ChemInform Abstract: Recent Advances in Iridium‐Catalyzed Alkylation of C—H and N—H Bonds

AbstractReview: 76 refs.

Recent Advances in Iridium-Catalyzed Alkylation of C–H and N–H Bonds

Over the past few years, iridium complexes have been widely used in the direct functionalization of unactivated bonds. In the presence of iridium catalysts, inactive C–H and N–H bonds have been transformed into C–C and N–C bonds in dehydrative alkylation using alcohols, allylation using allyl carbonates, and alkylation using alkenes. Enantioselective variants of some reactions have also been reported.

Synchronizing Steric and Electronic Effects in {RuII(NNNN,P)} Complexes: The Catalytic Dehydrative Alkylation of Anilines by Using Alcohols as a Case Study

A series of new hexacoordinated {Ru(II)(NNNN,P)} complexes was prepared from [RuCl(2)(R(3)P)(3)]. Their structure was determined by X-ray crystallography. The catalytic potential of this new class of complexes was tested in the alkylation of aniline with benzyl alcohol. In this test reaction, the influence of the counteranion plus electronic influences at the tetradentate ligand and the phosphine ligand were examined. The electrochemistry of all complexes was studied by cyclic voltammetry. Depending on the substituent at the ligand backbone, the complexes showed a different behavior. For all N-benzyl substituted complexes, reversible Ru(II/III) redox potentials were observed, whereas the N-methyl substituted complex possessed an irreversible oxidation event at small scan rates. Furthermore, the electronic influence of different substituents at the ligand scaffold and at the phosphine on the Ru(II/III) redox potential was investigated. The measured E(0) values were correlated to the theoretically determined HOMO energies of the complexes. In addition, these HOMO energies correlated well with the reactivity of the single complexes in the alkylation of aniline with benzyl alcohol. The exact balance of redox potential and reactivity appears to be crucial for synchronizing the multiple hydrogen-transfer events. The optimized catalyst structure was applied in a screening on scope and limitation in the catalytic dehydrative alkylation of anilines by using alcohols.

ChemInform Abstract: In‐Water Dehydrative Alkylation of Ammonia and Amines with Alcohols by a Polymeric Bimetallic Catalyst.

AbstractThe polymeric catalyst, prepared from a poly(catechol borate) and an Ir‐C5Me5 complex, is effective in the reaction of various primary and secondary amines with alcohols.

In-Water Dehydrative Alkylation of Ammonia and Amines with Alcohols by a Polymeric Bimetallic Catalyst

An in-water dehydrative alkylation with a novel heterobimetallic polymeric catalyst is described. Thus, a boron-iridium heterobimetallic polymeric catalyst was prepared by ionic convolution of a poly(catechol borate) and an iridium complex. The alkylation of ammonia and amines with alcohols, alkylating agents, was performed with 1 mol % Ir of the heterogeneous catalyst in water without the use of organic solvents under aerobic conditions to give the corresponding alkylated amines.

A Mitsunobu route to C-glycosides

C-Glycosides were successfully prepared via dehydrative alkylation under Mitsunobu conditions, using substituted sulfonyl methanes as nucleophiles. The materials prepared were converted to useful C-glycoside intermediates. An application of this approach toward the synthesis of C-glycolipids is presented.

Three‐Component Indium‐Mediated Domino Allylation of 1H‐Indole‐3‐carbaldehyde with Electron‐Rich (Hetero)arenes: Highly Efficient Access to Variously Functionalized Indolylbutenes

AbstractWe have developed a three‐component, one‐pot domino reaction that combines the allylindation of 1H‐indole‐3‐carbaldehyde with the dehydrative alkylation of stabilized Cnucleophiles (e.g., electron‐rich heteroarenes, electron‐rich aromatics, and stabilized enols) or N nucleophiles (e.g., azoles). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Stereoselective Formation of Carbon−Carbon Bonds via SN2-Displacement: Synthesis of Substituted Cycloalkyl[b]indoles

A general asymmetric synthesis of substituted cycloalkyl[b]indoles has been accomplished. The key features of this approach are (1) the utilization of a Japp-Klingemann condensation/Fischer cyclization to prepare cycloalkyl[b]indolones, (2) the asymmetric borane reduction of these heterocyclic ketones with (S)-OAB to obtain enantiomerically pure alcohols, and (3) the stereoselective S(N)2-displacement of these indole alcohol substrates with a carbon nucleophile under Mitsunobu conditions to set the C1 or C3 tertiary carbon stereocenter. The use of trimethylphosphine (PMe3) and bis(2,2,2-trichloroethyl) azodicarboxylate (TCEAD) was found to have an effect on the Mitsunobu dehydrative alkylation.