Reaction Of Allylic Alcohols Research Articles

Tethered Silanoxyiodination of Alkenes.

We present the first examples of tethered silanoxyiodination reactions of allylic alcohols. The products are useful silanediol organoiodide synthons and are formed with high regioselectivity and diastereocontrol. The reaction is scalable greater than 10-fold without loss of yield or selectivity. Furthermore, the products are starting materials for further transformations, including deiodination, C-N bond installation, epoxide synthesis, and desilylation. DFT calculations provide a basis for understanding the exquisite 6-endo selectivity of this silanoxyiodination reaction and show that the observed products are both kinetically and thermodynamically preferred.

Recent Advances in the Synthetic Use of Migration Reactions of Allyl Alcohols

AbstractAllyl alcohol compounds are widely used structural units. In recent years, considerable attention has been devoted to exploring the migration reactions of allyl alcohols via semipinacol or neophyl rearrangements, and so on, providing an attractive and powerful strategy for obtaining various important carbonyl compounds.However, to date, no review has been published that summarizes the significant advances in the preparation of functionalized carbonyl compounds using these migration rearrangement reactions. In this paper, the latest progress in the use of allyl alcohols as flexible synthons involving group migration is introduced, and the reaction scopes, limitations, and some of the mechanisms are also discussed.magnified image

Synthesis of 1,4-enynes via nickel-catalyzed cross-coupling of allylic alcohols with alkynylzinc reagents.

Synthesis of 1,4-enynes was performed via nickel-catalyzed cross-coupling of allylic alcohols with alkynylzinc reagents. The reaction features high regio- and E/Z-selectivity when aryl-substituted allylic alcohols were employed. The method also exhibits a wide scope of substrates and good compatibility of functional groups.

The Heck reaction of allylic alcohols catalysed by an N-heterocyclic carbene-Pd(ii) complex and toxicity of the ligand precursor for the marine benthic copepod Amphiascoides atopus.

The palladium-catalysed reaction of aryl halides and allylic alcohols is an attractive method for obtaining α,β-unsaturated aldehydes and ketones, which represent key intermediates in organic synthesis. In this context, a 1,2,3-triazol-5-ylidene (aNHC)-based palladium(ii) complex formed in situ has been found to be a selective catalyst for the syntheses of building blocks from the corresponding aryl halides and allylic alcohols, with yields ranging from 50% to 90%. The lack of toxic effects of the ligand precursor (1,2,3-triazolium salt) of the palladium(ii) complex for the harpacticoid copepod Amphiascoides atopus allowed us to contrast the efficiency of the catalytic system with the potential impact of the principal waste chemical in global aquatic ecosystems, which has not been previously addressed.

A Construction of α-Alkenyl Lactones via Reduction Radical Cascade Reaction of Allyl Alcohols and Acetylenic Acids.

An iron-catalyzed cascade reaction of radical reduction of allyl alcohols and acetylenic acids to construct polysubstituted α-alkenyl lactones has been developed. In this paper, various allyl alcohols can form allyl ester intermediates and are further transformed into alkyl radicals, which form products through intramolecular reflex-Michael addition. In addition, this method can be used to prepare spirocycloalkenyl lactones. Interestingly, this protocol can be used to synthesize the skeleton structure of natural products. Moreover, the product can be further transformed into a β-methylene tetrahydrofuran and tetrahydrofuran diene.

Heterobimetallic Eu(iii)/Pt(ii) single-chain nanoparticles: a path to enlighten catalytic reactions.

We introduce the formation and characterization of heterometallic single-chain nanoparticles entailing both catalytic and luminescent properties. A terpolymer containing two divergent ligand moieties, phosphines and phosphine oxides, is synthesized and intramolecularly folded into nanoparticles via a selective metal complexation of Pt(ii) and Eu(iii). The formation of heterometallic Eu(iii)/Pt(ii) nanoparticles is evidenced by size exclusion chromatography, multinuclear NMR (1H, 31P{1H}, 19F, 195Pt) as well as diffusion-ordered NMR and IR spectroscopy. Critically, we demonstrate the activity of the SCNPs as a homogeneous and luminescent catalytic system in the amination reaction of allyl alcohol.

Anodic Oxidation for the Stereoselective Synthesis of Heterocycles.

Stereodefined aliphatic heterocycles are one of the fundamental structural motifs observed in natural products and biologically active compounds. Various strategies for the synthesis of these building blocks based on transition metal catalysis, organocatalysis, and noncatalytic conditions have been developed. Although electrosynthesis has also been utilized for the functionalization of aliphatic heterocycles, stereoselective transformations under electrochemical conditions are still a challenging field in electroorganic chemistry. This Account consists of four main topics related to our recent efforts on the diastereo- and/or enantioselective synthesis of aliphatic heterocycles, especially N-heterocycles, using anodic oxidations as key steps. The first topic is the development of stereoselective synthetic methods for multisubstituted piperidines and pyrrolidines from anodically prepared α-methoxy cyclic amines. Our strategies were based primarily on N-acyliminium ion chemistry, and the key electrochemical transformations were diastereoselective anodic methoxylation, diastereoselective arylation, and anodic deallylative methoxylation. Furthermore, we found a unique property of the N-cyano protecting group that enabled the electrochemical α-methoxylation of α-substituted cyclic amines. The second topic of investigation is memory of chirality in electrochemical decarboxylative methoxylation. We observed that the electrochemical decarboxylative methoxylation of oxazolidine and thiazolidine derivatives with the appropriate N-protecting group occurred in a stereospecific manner even though the reaction proceeded through an sp2 planar carbon center. Our findings demonstrated the first example of memory of chirality in N-acyliminium ion chemistry. The third topic is the synthesis of chiral azabicyclo-N-oxyls and their application to chiral organocatalysis in the electrochemical oxidative kinetic resolution of secondary alcohols. The final topic is stereoselective transformations utilizing anodically generated halogen cations. We investigated the oxidative kinetic resolution of amino alcohol derivatives using anodically generated bromo cations. We also developed an intramolecular C-C bond formation of keto amides, a diastereoselective bromoiminolactonization of α-allyl malonamides, and an oxidative ring expansion reaction of allyl alcohols. It is noteworthy that most of the electrochemical reactions were performed in undivided cells under constant-current conditions, which avoided a complicated reaction setup and was beneficial for a large-scale reaction. In addition, we developed some enantioselective electrochemical transformations that are still challenges in electroorganic chemistry. We hope that our research will contribute to the further development of diastereo- and/or enantioselective transformations and the construction of valuable heterocyclic compounds using an electrochemical approach.

Synthesis of Allylsilanes via Nickel-Catalyzed Cross-Coupling of Silicon Nucleophiles with Allyl Alcohols.

NiCl2(PMe3)2-catalyzed reaction of allyl alcohols with silylzinc reagents, including PhMe2SiZnCl, Ph2MeSiZnCl, and Ph3SiZnCl, was performed, achieving allylsilanes in high yields. Aryl- and heteroaryl-substituted allyl alcohols, (E)-3-arylprop-2-en-1-ols, 1-aryl-prop-2-en-1-ols, and (E)-1-phenylpent-1-en-3-ol can be employed in the transformation. A range of functional groups as well as heteroaryl groups were tolerated. Reaction exhibited high regioselectivity and E/Z-selectivity when 1- or 3-aryl-substituted allyl alcohols were used as the substrates. Reaction of chiral allyl alcohol, (S,E)-1-phenylpent-1-en-3-ol, yielded a configuration-inversion product (R,E)-dimethyl(phenyl)(1-phenylpent-1-en-3-yl)silane.

Iron(III) Chloride/Phenylsilane‐Mediated Cascade Reaction of Allyl Alcohols with Maleimides: Synthesis of Poly‐Substituted γ‐Butyrolactones

AbstractA iron‐catalyzed free radical cascade reaction of allyl alcohols with N‐substituted maleimides for accessing poly‐substituted γ‐butyrolactones has been developed. In this protocol, various allyl alcohols can open N‐substituted maleimide rings to form allyl ester intermediates, and the allyl ester intermediates can be converted into an allyl ester alkyl radicals and undergo intramolecular free radical addition cyclization to form a polysubstituted γ‐butyrolactones. In this protocol, spiro γ‐butyrolactone compounds can be also synthesized. Meanwhile, the strategy could be applied to further construct a fully substituted tetrahydrofuran. The reaction is not sensitive to oxygen or moisture and has been performed on gram‐scale.magnified image

Synthesis of Hierarchically Porous Zeolite Ti-MWW with Different Hard Templates and Their Application in Allyl Alcohol Conversion

Diffusion limitation caused by microporous molecular sieves has always been a bottleneck problem in liquid phase epoxidation. In this study, several different carbon sources were used as hard templates to prepare hierarchically porous zeolite Ti-MWW (cTi-MWW) successfully. Compared with conventional Ti-MWW, cTi-MWW has an additional hierarchically porous structure and abundant pore structure distribution. Especially, the cTi-MWW prepared with polyethylene glycol1540 (PEG) as the hard template not only has a multiple hierarchically porous structure, but also exhibits small crystal size and good hydrophobicity properties studied by TEM and in situ FT-IR. At the same time, the cTi-MWW prepared with PEG exhibits better activity than the conventional Ti-MWW in the selective epoxidation reaction of allyl alcohol (AAL) with H2O2 as oxidant and the conversion is improved by 11% (Si/Ti = 20). And a higher efficiency and longer catalyst life in fixed-bed catalytic reactor were exhibited by using cTi-MWWPEG as catalyst. The physicochemical properties of cTi-MWW prepared with different hard templates were systematically studied by SEM, XPS, UV–Vis, XRD and N2 absorption–desorption techniques. This method is effective for the synthesis of cTi-MWW and significant for the preparation of hierarchically porous zeolites in industrial production. A hierarchically porous zeolite Ti-MWW prepared with different hard templates successfully. With the hierarchically porous structure, which have better adsorption, diffusion, and reactivity in liquid phase epoxidation, thus improving the catalytic activity. Especially, the hierarchically porous zeolite Ti-MWW prepared with polyethylene glycol exhibits small crystal size and good hydrophobicity properties.

Enantioselective Synthesis of cis- and trans-Borocyclopropylmethanol: Simple Building Blocks To Access Heterocycle-Substituted Cyclopropylmethanols

An enantioselective and non-oxidative methodology was developed to obtain enantioenriched cyclopropyl boronates using a diethanolamine-promoted selective decomplexation of dioxaborolane. The non-oxidative decomplexation of the dioxaborolane ligand from the cyclopropylmethoxide species formed in the dioxaborolane-mediated Simmons–Smith cyclopropanation reaction provided the enantio­enriched CIDA-based (CIDA = N-cyclohexyliminodiacetic acid) boro­cyclopropane in 92% yield and 95.6:4.4 er. A robustness screen has shown diethanolamine to be compatible with esters, carbamates and N-heterocycles, providing a tool to access enantioenriched cyclopropanes carrying not only base-sensitive but oxidizable functional groups as well. Diethanolamine was found to be compatible with the modified zinco-cyclopropanation reaction of allyl alcohol to remove residual dioxaborolane from the corresponding cis-N-heterocycle cyclopropylmethanol, thereby leading to improved yields.

Catalytic Radical-Polar Crossover Reactions of Allylic Alcohols.

Radical-polar crossover hydrofunctionalizations of tertiary allylic alcohols are described. Depending on the structure of the catalyst, corresponding epoxides or semipinacol rearrangement products are selectively obtained in good yields. Experimental evidence points to the participation of alkylcobalt complexes as electrophilic intermediates.

Preparation of Rearranged Allylic Isocyanates from the Reaction of Allylic Alcohols with 1-Cyano-4-dimethylaminopyridinium Bromide

A shorter and less costly alternative to Ichikawa’s [1,3]-transposition protocol for cyanates to isocyanates is described.

Rhenium-catalyzed α-alkylation of enol acetates with alcohols or ethers

When benzylic and allylic alcohols were treated with enol acetate in the presence of a catalytic amount of a rhenium complex, ReBr(CO)5, the carbon-carbon bond formation of the alcohols and enol acetate smoothly proceeded to give the corresponding ketones and aldehyde in moderate to good yields. For the reaction of allylic alcohols, γ,δ-unsaturated carbonyl compounds were obtained in good yields. When ethers were used instead of alcohols as the alkylated agent, two alkyl moieties on the ethers were utilized on the reaction.

Recent Advances in the Synthesis of β-Functionalized Ketones by Radical-Mediated 1,2-Rearrangement of Allylic Alcohols.

β-Functionalized ketones are a highly important and valuable class of compounds that have gained increasing attention from organic chemists due to their intensive uses as versatile synthetic intermediates and building blocks in complex molecule assembly and natural product synthesis. Accordingly, there is continuing interest in the development of new approaches for the synthesis of β-functionalized ketones. In recent years, radical-mediated 1,2-rearrangement reactions of allylic alcohols, which proceed through cationic (semipinacol) rearrangements or radical (neophyl) rearrangements, have presented an attractive and powerful strategy to access various diversely β-functionalized ketones. Interestingly, this strategy allows for the direct installation of a variety of valuable functional groups at the β-position of cyclic and acyclic ketones by employing different radical precursors. However, a review focusing on the preparation of β-functionalized ketones by radical-mediated 1,2-rearrangement reactions of allylic alcohols has not been summarized to date. This Minireview highlights recent progress made in this highly active and interesting research area, and the corresponding mechanisms will also be discussed.

Synthesis of β-heteroaryl carbonyl compounds via direct cross-coupling of allyl alcohols with heteroaryl boronic acids under cooperative bimetallic catalysis

The eco-friendly cooperative Cu/Pd-catalyzed oxidative Heck reaction of allyl alcohols with heteroaryl boronic acids under air was described. The ready availability of starting materials and the mild reaction conditions made this protocol a safe and operationally convenient strategy for the efficient synthesis of β-heteroaryl carbonyl compounds.

Eosin Y-catalyzed, visible-light-promoted carbophosphinylation of allylic alcohols via a radical neophyl rearrangement.

A visible-light-promoted phosphinylation of allylic alcohols with concomitant 1,2-aryl migration is described. This transformation proceeds smoothly under metal-free and mild conditions by using an inexpensive organic dye, eosin Y, as the photocatalyst, affording various β-aryl-γ-ketophosphine oxides in moderate to good yields. Mechanistic studies suggested that the 1,2-aryl migration proceeded through a radical (neophyl) rearrangement.

Copper-catalyzed tandem radical amination/1,2-carbon migration of allylic alcohols: Direct access to α-quaternary-β-amino ketones

A novel nitrogen-centered radical-induced 1,2-carbon migration reaction of allylic alcohols has been developed. This method provides easy access to a variety of α-quaternary-β-amino ketones under mild reaction conditions. The reaction has a wide substrate scope and operational simplicity. Mechanistic studies suggest that 1,2-carbon migration is induced by regioselective nitrogen-centered radical addition to the alkene unit.

A Formal anti-Markovnikov Hydroalkoxylation of Allylic Alcohols with a Ruthenium Catalyst

Hydroalkoxylation of C–C double bonds was achieved through the use of a ruthenium catalyst. The reaction of allylic alcohols with nucleophilic alcohols was carried out in the presence of a ruthenium catalyst prepared by RuClH(CO)(PPh3)3 and 2,6-bis(n-butyliminomethyl)-4-(piperidin-1-yl)pyridine under mild reaction conditions to afford the corresponding γ-alkoxypropanols in good yield.

Copper-Catalyzed Enantioselective Domino Arylation/Semipinacol Rearrangement of Allylic Alcohols with Diaryliodonium Salts.

A copper-catalyzed enantioselective arylative semipinacol rearrangement of allylic alcohols was developed. In the presence of a catalytic amount of an in situ generated chiral copper-bisoxazoline complex, reaction of allylic alcohols with diaryliodonium salts afforded spirocycloalkanones in high yields with high diastereo- and enantioselectivities. A two-point binding model engaging the carbon-carbon double bond and the proximal hydroxyl group was proposed to be responsible for the highly efficient chirality transfer.