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We present herein a catalytic enantioconvergent diamination of racemic allylic alcohols with the construction of two C−N bonds and 1,3‐nonadjacent stereocenters. This iridium/chiral phosphoric acid cooperative catalytic system operates through an atom‐economical borrowing hydrogen amination/aza‐Michael cascade, and converts readily available phenylenediamines and racemic allylic alcohols to 1,5‐tetrahydrobenzodiazepines in high enantioselectivity. An intriguing solvent‐dependent switch of diastereoselectivity was also observed. Mechanistic studies suggested a dynamic kinetic resolution process involving racemization through a reversible Michael addition, making the last step of asymmetric imine reduction the enantiodetermining step of this cascade process. [ABSTRACT FROM AUTHOR]

Geometrically defined allylic alcohols with SE, SZ, RE and RZ stereoisomers serve as valuable intermediates in synthetic chemistry, attributed to the stereoselective transformations enabled by the alkenyl and hydroxyl functionalities. When an ideal scenario presents itself with four distinct stereoisomers as potential products, the simultaneous control vicinal stereochemistry in a single step would offer a direct pathway to any desired stereoisomer. Here, we unveil a metallaphotoredox migration strategy to access stereodefined allylic alcohols through vinylic C−H activation with aldehydes. This method harnesses a chiral nickel catalyst in concert with a photocatalyst to enable a 1,4‐Ni migration by using readily accessible 2‐vinyl iodoarenes as starting materials. The efficacy of this methodology is highlighted by the precise construction of all stereoisomers of allylic alcohols bearing analogous substituents and the efficient synthesis of key intermediates en route to Myristinin family. Experimental and computational studies have shed light on pivotal aspects including the synergy of metal catalysis and photocatalysis, the driving forces behind the migration, and the determination of absolute configuration in the C−H addition process. [ABSTRACT FROM AUTHOR]

A Pd(II)‐catalyzed formal [5+2] coupling‐cyclization of 2‐arylbenzaldehydes with allylic alcohols has been developed. The method provides an efficient approach to access diaryl‐fused cycloheptene skeletons via traceless α‐amino acid‐assisted Csp2−H activation process. [ABSTRACT FROM AUTHOR]

The regiospecific Cα−Cβ cleavage of allylic alcohols under modified aerobic Mukaiyama hydration conditions is presented. The new methodology can be regarded as an equivalent of a two‐step process, a typical hydration of the parent allylic alcohol followed by a 1,2‐diol cleavage. A broad scope of substrates, both cyclic and acyclic, are applicable, thus introducing substantial structural modification to the core, especially of the former type of substrates. Mechanistic investigation of the reaction reveals the importance of the nearby hydroxyl group for the deviation from the typical Mukaiyama hydration pathway. [ABSTRACT FROM AUTHOR]

Chiral allylic alcohols are highly prized in synthetic chemistry due to their versatile reactivity stemming from both alkenyl and hydroxyl functionalities. While the Nozaki–Hiyama–Kishi (NHK) reaction is a widely used method for the synthesis of allylic alcohols, it suffers from drawbacks such as the use of toxic chromium salts, high amounts of metal reductants, and poor enantiocontrol. To address these limitations, we present a novel approach involving a metallaphotoredox‐catalyzed asymmetric NHK reaction for the production of chiral allylic alcohols. This method marries alkenyl (pseudo)halides with aldehydes, leveraging a synergistic blend of a chiral nickel catalyst and a photocatalyst. This innovative technique enables both oxidative addition and insertion just using nickel, diverging significantly from the conventional NHK reaction pathway mediated by nickel and chromium salts. The adoption of this methodology holds immense promise for crafting a spectrum of intricate compounds, particularly those of significance in pharmaceuticals. Detailed experimental investigations have shed light on the metallaphotoredox process, further enhancing our understanding and enabling further advancements. [ABSTRACT FROM AUTHOR]

A domino reaction comprising four consecutive steps based on the strategy of isomerization of allylic alcohols was developed. This base‐catalyzed protocol provided an approach for constructing polysubstituted quinolines without additional additives. A wide range of di‐ or trisubstituted γ‐aminoaryl allylic alcohols bearing alkyl or (hetero)aryl substituents were transformed to a range of structurally diverse quinolines. The utility of this transformation was demonstrated by the application in the concise synthesis of several polysubstituted quinoline derivatives, including natural products and pharmacological agents. Preliminary mechanistic experiments suggest that the isomerization of γ‐aminoaryl allylic alcohol proceeds via an intramolecular 1,3‐hydrogen shift whereas for the aromatization of the dihydroquinoline intermediate two possible pathways exist: acceptorless dehydrogenation and transfer hydrogenation. [ABSTRACT FROM AUTHOR]

A visible‐light‐induced method was developed to synthesize selenylated cyclic boronic esters through intermolecular oxyselenenylation. This method can be performed under additive‐free and photocatalyst‐free conditions and generates potentially pharmaceutically useful heterocycles. A plausible reaction mechanism was proposed based on several control experiments and previous reports. [ABSTRACT FROM AUTHOR]

The PhI(OAc)2 -promoted 1,2-transfer reaction between allylic alcohols and thiophenols, conducted in an argon atmosphere, has proven to be effective in producing β-carbonyl sulfides from 1,1-disubstituted allylic alcohols in high yields. This method offers a fast and efficient way to synthesize β-carbonyl sulfides, which are valuable intermediates in organic synthesis. This discussion focuses on the effects of the oxidizer, temperature, and solvent on the reaction. A proposed tentative mechanism for this reaction is also discussed. [ABSTRACT FROM AUTHOR]

An exclusive anti‐Markovnikov hydroamination as well as hydroalkoxylation of allylic alcohols catalyzed by a simple catalyst Y(CH2SiMe3)3(THF)2 has been developed, providing a variety of γ‐amino and γ‐alkoxy alcohols in good yields under mild conditions. Moreover, this protocol is applied to the synthesis of drug molecules Propipocaine and Proroxan. The rare‐earth metal catalyst features readily available, wide substrate compatability, exclusive anti‐Markovnikov selectivity, and performs in the absence of a base or an additive. [ABSTRACT FROM AUTHOR]

Allylic alcohols are a privileged motif in natural product synthesis and new methods that access them in a stereoselective fashion are highly sought after. Toward this goal, we found that chiral acetonide‐protected polyketide fragments performing the Hoppe–Matteson–Aggarwal rearrangement in the absence of sparteine with high yields and diastereoselectivities rendering this protocol a highly valuable alternative to the Nozaki–Hiyama–Takai–Kishi reaction. Various stereodyads and ‐triads were investigated to determine their substrate induction. The mostly strong inherent stereoinduction was attributed to a combination of steric and electronic effects. [ABSTRACT FROM AUTHOR]

The intermolecular cyclization of phenols with a small excess of allylic alcohols in the presence of a Bi(OTf)3 catalyst under air without any additives afforded the corresponding O‐containing heterocyclic compounds. Bi(OTf)3‐catalyzed intermolecular cyclization of phenols with 3‐methylbut‐2‐en‐1‐ol gave the corresponding O‐containing 6‐membered ring; chroman derivatives (16 varieties). The catalytic intermolecular cyclization of phenols with 2‐methylprop‐2‐en‐1‐ol led to the corresponding O‐containing 5‐membered ring; naphtho‐ or benzofurans (5 varieties). The intermolecular catalytic cyclization of 2,3,5,6‐trimethylbenzene‐1,4‐diol with a small excess of phytols produced vitamin E (DL‐α‐tocopherol) in excellent yields under mild reaction conditions. [ABSTRACT FROM AUTHOR]

A radical‐induced dichloromethylation and concomitant 1,2‐aryl migration of allylic alcohols with CHCl3 is developed for the construction of γ,γ‐dichloroketones in moderate to good yields. We found that, for the para‐substituted unsymmetrical substrates, the more electron‐deficient aryl group migrates preferentially over the more electron‐rich aryl group. Moreover, chlorocyclopropanes could be obtained from allyl alcohols in one‐pot manner through radical‐addition/1,2‐aryl migration/nucleophilic substitution. [ABSTRACT FROM AUTHOR]

A radical‐induced dichloromethylation and concomitant 1,2‐aryl migration of allylic alcohols with CHCl3 is developed for the construction of γ,γ‐dichloroketones in moderate to good yields. We found that, for the para‐substituted unsymmetrical substrates, the more electron‐deficient aryl group migrates preferentially over the more electron‐rich aryl group. Moreover, chlorocyclopropanes could be obtained from allyl alcohols in one‐pot manner through radical‐addition/1,2‐aryl migration/nucleophilic substitution. [ABSTRACT FROM AUTHOR]

Low transition temperature mixtures (LTTMs) are a new generation of solvents that have found extensive application in organic synthesis. The interactions between the components often generate highly activated, catalytically active species, thus opening the possibility of using LTTMs as catalysts, rather than solvents. In this work, we introduce a nickel-based imidazolium LTTM, study its thermal behavior and explore its catalytic activity in the solvent-free allylation of heterocycles with allylic alcohols. This system is effective in this reaction, affording the corresponding products in excellent yield without the need for additional purifications, thus resulting in a very environmentally friendly protocol. [ABSTRACT FROM AUTHOR]

Transition metal‐catalyzed divergent synthesis through alternation of the catalyst is appealing, as it provides an operationally simple way to access different valuable products, while using the same reactants as starting materials. Herein, a gold‐catalyzed cascade reaction of conjugated diynamides with allylic alcohols is described. By variation of the catalysts, substituted allenes and furans could be obtained selectively. Mechanistic studies indicate that, after the addition of allylic alcohol to gold‐activated diynamide, a [3,3]‐sigmatropic rearrangement would take place and lead to the formation of a common reactive intermediate, which would further convert to the final products selectively. Further variation of the structure of diynamides has unveiled an additional reaction sequence involving intramolecular Himbert arene/allene Diels‐Alder cycloaddition to afford a series of dearomatized products bearing bicyclo[2,2,2]octadiene core. [ABSTRACT FROM AUTHOR]

A rapid and efficient acid‐promoted strategy to access allylic thiocyanates using allylic alcohols as substrates and easily‐available NH4SCN as the thiocyanate source is presented under metal‐ and oxidant‐free conditions. Through screening of various kinds of acids, organic and strong trifluoroacetic acid (TFA) was found most effective. Testing of substrates showed that the strategy has remarkable functional group tolerance. A possible mechanism is provided, and the gram‐scale experiment demonstrate that this novel protocol has potential industrial application value. [ABSTRACT FROM AUTHOR]

Wang, K. K. Toh, E. P. J. Ng, S. Chiba, J. Am. Chem. Soc. 2011, 133, 6411 - 6421; 74 Y. Wang, S. Chiba, J. Am. Chem. Soc. 2009, 131, 12570 - 12572. 8 E. Nakamura, S. Aoki, K. Sekiya, H. Oshino, I. Kuwajima, J. Am. Chem. Soc. 1987, 109, 8056 - 8066; 9 E. Nakamura, I. Kuwajima, J. Am. Chem. Soc. 1984, 106, 3368 - 3370. Keywords: potassium; ketones; allylic alcohols; homoenolates; dianions EN potassium ketones allylic alcohols homoenolates dianions 826 833 8 03/27/23 20230321 NES 230321 This study reports the synthesis of diverse -functionalized ketones from readily available 1-arylallylic alcohols in the presence of (trimethylsilyl)methylpotassium (TMSCH SB 2 sb K). 5 E. Nakamura, H. Oshino, I. Kuwajima, J. Am. Chem. Soc. 1986, 108, 3745 - 3755; 6 E. Nakamura, I. Kuwajima, J. Am. Chem. Soc. 1983, 105, 651 - 652; 7 E. Nakamura, I. Kuwajima, J. Am. Chem. Soc. 1977, 99, 7360 - 7362. [Extracted from the article]

The epoxidation process of semi-synthetic triterpenoids 2-methyl-3-oxo-19β,28-epoxy- 18α-olean-1-ene, and its allylic alcohol derivatives were examined. 1,2α-epoxide, as the main product, was found to be formed from the starting enone exposed to m-chloroperbenzoic acid (mCPBA). In the case of hydroxy-directed mCPBA-oxidation of triterpenic allyl alcohols and their 3α-alkyl-substituted derivatives, inversion of C1 and C2 asymmetric centers with the formation of 1,2β-epoxyalcohols took place. The synthesis of 2,3α-epoxides was fulfilled from 2,3-dialkyl-substituted C(3) allyl alcohols by the action of pyridinium chlorochromate under [1,3]-oxidative rearrangement conditions. The transformations brought about enabled chiral oleanane derivatives with an oxygen-containing substituent at the C1, C2, and C3 atoms to be obtained. The study also provides information on in silico PASS prediction of pharmacological effects and in vitro evaluation of the cytotoxic activity of the synthesized compounds. [ABSTRACT FROM AUTHOR]

Allylic amines are useful building blocks in organic synthesis, so the development of green and efficient methods for the preparation of allylic amines are of great importance. An Fe‐catalyzed amidation of allylic alcohols with chiral tert‐butylsulfinamide has been developed. With water as the only by‐product, a range of synthetically useful chiral sulfinamide olefin derivatives (30 examples) were obtained under mild reaction conditions. The reaction can be performed on a gram‐scale, and the products could serve as chiral ligands for asymmetric catalysis. Mechanistic studies suggest that the reaction proceeds by an Fe‐catalyzed borrowing hydrogen process, which is different from most of the reported allylic amination reactions. [ABSTRACT FROM AUTHOR]

Unspecific Peroxygenases (UPOs) catalyze the selective oxygenation of organic substrates using only hydrogen peroxide as the external oxidant. The PaDa-I variant of the UPO from Agrocybe aegerita catalyses the oxidation of Z- and E-allylic alcohols with complementary selectivity, giving epoxide and carboxylic acid/aldehyde products respectively. Both reactions can be performed on preparative scale with isolated yields up to 80%, and the epoxidations proceed with excellent enantioselectivity (>99% ee). The divergent reactions can also be used to transform E/Z mixtures of allylic alcohols, enabling both product series to be isolated from a single reaction. The utility of the epoxidation method is exemplified in the total synthesis of both enantiomers of the insect pheromone disparlure, including a highly enantioselective gram-scale transformation. These reactions provide further evidence for the potential of UPOs as catalysts for the scalable preparation of important oxygenated intermediates., (© 2024 Wiley‐VCH GmbH.)

Low transition temperature mixtures (LTTMs) are a new generation of solvents that have found extensive application in organic synthesis. The interactions between the components often generate highly activated, catalytically active species, thus opening the possibility of using LTTMs as catalysts, rather than solvents. In this work, we introduce a nickel-based imidazolium LTTM, study its thermal behavior and explore its catalytic activity in the solvent-free allylation of heterocycles with allylic alcohols. This system is effective in this reaction, affording the corresponding products in excellent yield without the need for additional purifications, thus resulting in a very environmentally friendly protocol.

A nickel‐catalyzed three‐component carbonylative cross‐coupling reaction of allylic alcohols and organoalanes with CO at atmospheric pressure is reported, enabling the expedient formation of β,γ‐unsaturated ketones with broad scope. Particularly, the chemoselective allylic carbonylation of diols further highlights the practicability of this protocol. The leverage of organoalanes as both the coupling components and the activators for the alcohol functionalization is crucial for this method, thus no extraneous activators are required. [ABSTRACT FROM AUTHOR]

The lipase from Burkholderia cepacia (BCL) was immobilized through physical adsorption on pristine and functionalized multiwalled carbon nanotubes (MWCNTs) with carboxyl or amine groups and used in the stereoselective acylation of (R,S)‐1‐octen‐3‐ol (1) and (R,S)‐(E)‐4‐phenyl‐3‐buten‐2‐ol (4) with vinyl acetate. All immobilized preparations produced better results than free BCL. For (R,S)‐4, 50% conversion and E > 200 were obtained in n‐hexane or in solvent‐free medium. For (R,S)‐1, in solvent‐free medium, the conversion was 38% with a slight increase in the E‐value (E = 10). [ABSTRACT FROM AUTHOR]

A unique family of chiral peraza N6‐macrocyclic ligands, which are conformationally rigid and have a tunable saddle‐shaped cavity, is described. Utilizing their manganese(I) complexes, the first example of earth‐abundant transition metal‐catalyzed asymmetric formal anti‐Markovnikov hydroamination of allylic alcohols was realized, providing a practical access to synthetically important chiral γ‐amino alcohols in excellent yields and enantioselectivities (up to 99 % yield and 98 % ee). The single‐crystal structure of a MnI complex indicates that the manganese atom coordinates with the chiral dialkylamine moiety in a bidentate fashion. Further DFT calculations revealed that five of the six nitrogen atoms in the ligand were engaged in multiple noncovalent interactions with Mn, an isopropanol molecule, and a β‐amino ketone intermediate via coordination, hydrogen bonding, and/or CH⋅⋅⋅π interactions in the transition state, showing a remarkable role of the macrocyclic framework. [ABSTRACT FROM AUTHOR]

In the Sharpless asymmetric epoxidation of chiral secondary allylic alcohols, one substrate enantiomer is predominantly converted to the anti‐epoxy alcohol. We herein report the first highly syn‐selective epoxidation of terminal allylic alcohols using a titanium salalen complex as catalyst, at room temperature, and aqueous hydrogen peroxide as oxidant. With enantiopure terminal allylic alcohols as substrates, the epoxy alcohols were obtained with up to 98 % yield and up to >99 : 1 dr (syn). Catalyst loadings as low as 1 mol % can be applied without eroding the syn‐diastereoselectivity. Modification of the allylic alcohol to an ether does not affect the diastereoselectivity either [>99 : 1 dr (syn)]. Inverting the catalyst configuration leads to the anti‐product, albeit at lower dr (ca. 20 : 1). The synthetic potential is demonstrated by a short, gram‐scale preparation of a tetrahydrofuran building block with three stereocenters, involving two titanium salalen catalyzed epoxidation steps. [ABSTRACT FROM AUTHOR]

Catalytic asymmetric isomerization of allylic or homoallylic alcohols into synthetically useful carbonyl compounds is a redox‐neutral and 100 % atom‐economic transformation, which is of great interest and has gained increasing attention from both academic and industry. This minireview summarizes the advances in catalytic enantioselective isomerization and it involved tandem reactions over the past five years, also discusses their advantages and limitations, and expounds the synthetic chances still open for further development. [ABSTRACT FROM AUTHOR]

The isomerization of allylic alcohols is an important reaction because it can afford carbonyl compounds in an atom‐economical manner. Although base‐catalyzed methods are more desirable than those using transition‐metal catalysts from both the economic and environmental points of view, these methods have several drawbacks, such as narrow substrate scope and high catalyst loading. This paper reports the development of an efficient KOtBu/DMSO catalytic system suitable for the isomerization of a broad range of allylic alcohols with good yields, to which previously reported systems could not be applied. This catalytic system was successfully applied to a tandem allylic isomerization/electrophilic trapping reaction, thereby highlighting its synthetic utility. [ABSTRACT FROM AUTHOR]

Electrochemical synthesis has been rapidly developing over the past few years. Here, we report a practical and eco-friendly electrocatalytic isomerization of allylic alcohols to their corresponding carbonyl compounds. This reaction can be carried out in undivided cells without the addition of external chemical oxidants and metal catalysts. Moreover, this reaction features a broad substrate scope including challenging allylic alcohols bearing tri- and tetra-substituted olefins and affords straightforward access to diverse β-aryl-ketones. Mechanistic investigations suggest that the reactions proceed through a radical process. This study represents a unique example in which electrochemistry enables hydrogen atom transfer in organic allylic alcohol substrates using a simple organocatalyst. [ABSTRACT FROM AUTHOR]

The epoxidation process of semi-synthetic triterpenoids 2-methyl-3-oxo-19β,28-epoxy- 18α-olean-1-ene, and its allylic alcohol derivatives were examined. 1,2α-epoxide, as the main product, was found to be formed from the starting enone exposed to m-chloroperbenzoic acid (mCPBA). In the case of hydroxy-directed mCPBA-oxidation of triterpenic allyl alcohols and their 3α-alkyl-substituted derivatives, inversion of C1 and C2 asymmetric centers with the formation of 1,2β-epoxyalcohols took place. The synthesis of 2,3α-epoxides was fulfilled from 2,3-dialkyl-substituted C(3) allyl alcohols by the action of pyridinium chlorochromate under [1,3]-oxidative rearrangement conditions. The transformations brought about enabled chiral oleanane derivatives with an oxygen-containing substituent at the C1, C2, and C3 atoms to be obtained. The study also provides information on in silico PASS prediction of pharmacological effects and in vitro evaluation of the cytotoxic activity of the synthesized compounds.

A highly enantioselective NiH‐catalyzed hydrocyclization of alkynones with unparalleled anti‐ and endocyclic selectivities is described. The choice of the precatalysts has significant influence in tuning the regio‐ and enantioselectivity. Using Ni(OTs)2/Phox as a precatalyst and (EtO)2MeSiH as a hydride source, an array of enantioenriched O‐, N‐, and S‐containing heterocyclic tertiary allylic alcohols are obtained in 24–81 % yields with 80:20–99:1 er. Mechanistic investigations and synthetic application are also carried out. This study represents an efficient access to a set of allylic alcohols that are unable to access by the state‐of‐the‐art coupling reactions. [ABSTRACT FROM AUTHOR]

Allylic amines are valuable and functional building blocks. Direct N‐allylation of pyrazole and its derivatives as an atom economic strategy to provide allylic amines has been achieved only using commercial Bu4NHSO4 as the metal‐free catalyst and water as the solvent without any additives. 11–93% isolated yields were obtained for the N‐allylation of pyrazole and its derivatives with allylic alcohols. Bu4NHSO4 could be reused for six times by simple extraction nearly without loss of catalytic activity and was also suitable for a gram‐scale production. The reaction of allylic ether and pyrazole did not occur to give the desired product indicated that allylic ether was not the active intermediate in the pathway. Density functional theory (DFT) calculations reveal that there are hydrogen bonding effects among substrates, solvent and catalyst, especially the one formed between allylic alcohol and H2O. Control experiments in different protic solvents further demonstrate the intermolecular hydrogen bonding of allylic alcohol and water. [ABSTRACT FROM AUTHOR]

This study reports the first base‐promoted aldol–Tishchenko reactions of allylic alcohols with aldehydes initiated by allylic isomerization. The reaction enables the diastereoselective synthesis of a variety of 1,3‐diols with three contiguous stereogenic centers. Unlike commonly reported systems, our method allows the use of readily available allylic alcohols as nucleophiles instead of enolizable aldehydes and ketones. [ABSTRACT FROM AUTHOR]

Allylic alcohols form perrhenate esters upon reaction with Re2 O7 or HOReO3. These species undergo nonstereospecific and nonregiospecific alcohol-transposition reactions through cationic intermediates. Sequencing these nonselective processes with reversible trapping by electrophiles results in cyclization reactions where regio- and stereocontrol are dictated by thermodynamics. The cationic intermediates can also be utilized as electrophiles in intra- or intermolecular dehydrative reactions with nucleophiles. These processes serve as the basis for applications in catalytic syntheses of a wide range of heterocyclic and carbocyclic structures that often show considerable increases in molecular complexity. This Account describes a sequence of events that started from a need to solve a problem for the completion of a natural product synthesis and evolved into a central element in the design of numerous new transformations that proceed under mild conditions from readily accessible substrates. 1 Introduction 2 Exploratory Studies 3 Application to Spiroketal Synthesis 4 Reactions with Epoxides as Trapping Agents 5 Development of Dehydrative Cyclizations 6 Bimolecular Reactions 7 Spirocyclic Ether Formation 8 Conclusions [ABSTRACT FROM AUTHOR]

We report herein the first KHMDS‐catalyzed Michael additions of allylic alcohols to α,β‐unsaturated amides through allylic isomerization. The reaction proceeds smoothly in the presence of only 5 mol% of KHMDS to afford a variety of 1,5‐ketoamides in high yields. Mechanistic investigations, including experimental and computational studies, reveal that the KHMDS‐catalyzed in‐situ generation of the enolate from the allylic alcohol through a tunneling‐assisted 1,2‐hydride shift is the key to the success of this transformation. [ABSTRACT FROM AUTHOR]

Starting from readily available tertiary alcohols, four different reactions (a 1,3-migration of a hydroxy group, kinetic resolution, racemization, and an intramolecular Diels–Alder reaction) took place under co-catalysis by lipase and oxovanadium compounds in a one-pot process to produce polysubstituted tricyclic carbon frameworks in high yields and with high enantioselectivities. The key to the success of this process was the discovery that a silyl group attached to the terminal carbon of the vinyl moiety completely controls the direction of hydroxy group migration [ABSTRACT FROM AUTHOR]

Selective oxidation of benzylic and allylic alcohols to their corresponding aldehyde/ketone derivative without affecting saturated alcohols is still a challenging endeavor in organic synthesis. Various metal complexes, especially the copper complexes in the presence of TEMPO are being used very often for such transformations under aerobic conditions, but they are not selective to allylic and benzylic alcohols. The use of copper salt for oxidation of alcohols in the absence of a ligand are very scarcely studied except for the one catalyzed by CuCl/TEMPO where chloride inhibition and lack of selective oxidation have been noted upon use of CuCl2. Herein we report a Cu(OAc)2 catalyzed and TEMPO mediated selective aerobic oxidation of benzylic and allylic alcohols to aldehyde/ketone in the presence of Et2NH. The method avoids pre-synthesis of the catalyst as in the case of Cu(II)/(I) complexes/TEMPO catalyzed oxidation reactions, requires low catalyst loading, employs cheaper copper salt, and gives excellent selectivity for oxidation of benzylic and allylic alcohols. [ABSTRACT FROM AUTHOR]

A Rh(III)‐catalyzed Csp2−Csp3 bond cleavage/carbonylethylation of α‐indolyl alcohols with allylic alcohols has been reported. This transformation involved a cascade C−C bond cleavage/C−C bond formation, and provides a novel approach to assemble 2‐carbonylethylindole skeletons. [ABSTRACT FROM AUTHOR]

The PhI(OAc) 2 -promoted 1,2-transfer reaction between allylic alcohols and thiophenols, conducted in an argon atmosphere, has proven to be effective in producing β-carbonyl sulfides from 1,1-disubstituted allylic alcohols in high yields. This method offers a fast and efficient way to synthesize β-carbonyl sulfides, which are valuable intermediates in organic synthesis. This discussion focuses on the effects of the oxidizer, temperature, and solvent on the reaction. A proposed tentative mechanism for this reaction is also discussed.

We have used experimental studies and DFT calculations to investigate the IrIII‐catalyzed isomerization of allylic alcohols into carbonyl compounds, and the regiospecific isomerization–chlorination of allylic alcohols into α‐chlorinated carbonyl compounds. The mechanism involves a hydride elimination followed by a migratory insertion step that may take place at Cβ but also at Cα with a small energy‐barrier difference of 1.8 kcal mol−1. After a protonation step, calculations show that the final tautomerization can take place both at the Ir center and outside the catalytic cycle. For the isomerization–chlorination reaction, calculations show that the chlorination step takes place outside the cycle with an energy barrier much lower than that for the tautomerization to yield the saturated ketone. All the energies in the proposed mechanism are plausible, and the cycle accounts for the experimental observations. [ABSTRACT FROM AUTHOR]

A general and direct synthesis of dicarboxylic acids including industrially important adipic acid by palladium‐catalyzed dicarbonylation of allylic alcohol is reported. Specifically, the combination of PdCl2 and a bisphosphine ligand (HeMaRaphos) promotes two different carbonylation reactions with high activity and excellent selectivity. [ABSTRACT FROM AUTHOR]

Fluoroalkyl(hetero)arylation of allylic alcohols with perfluoroalkyl iodide or difluoroacetic acid as fluoroalkyl source was developed herein, delivering functionalized ketones containing an α‐quaternary center. Formation of the fluoroalkyl radical was followed by its intermolecular addition to alkenes and the migration of a (hetero)aryl group with the concomitant generation of a ketone group to finish the domino sequence. Mechanistic studies indicated that the aryl migration proceeded through neophyl rearrangement in a radical pathway. Moreover, preliminary antifungal evaluation against Magnaporthe grisea is also described for the first time. [ABSTRACT FROM AUTHOR]

We present herein an unprecedented allylative dicarbofunctionalization of alkynes with allylic alcohols. This simple catalytic procedure utilizes commercially available Ni(COD)2, triphenylphosphine, and inexpensive reagents, and delivers valuable skipped dienes and trienes with an all‐carbon tetrasubstituted alkene unit in a highly stereoselective fashion. Preliminary mechanistic studies support the reaction pathway of allylnickelation followed by transmetalation in this dicarbofunctionalization of alkynes. [ABSTRACT FROM AUTHOR]

Photoredox‐catalyzed isomerization of γ‐carbonyl‐substituted allylic alcohols to their corresponding carbonyl compounds was achieved for the first time by C−H bond activation. This catalytic redox‐neutral process resulted in the synthesis of 1,4‐dicarbonyl compounds. Notably, allylic alcohols bearing tetrasubstituted olefins can also be transformed into their corresponding carbonyl compounds. Density functional theory calculations show that the carbonyl group at the γ‐position of allylic alcohols are beneficial to the formation of their corresponding allylic alcohol radicals with high vertical electron affinity, which contributes to the completion of the photoredox catalytic cycle. [ABSTRACT FROM AUTHOR]

A modified pathway towards 5‐hydroxy‐isoxazolidines has been preliminarily investigated by taking advantage of the anti‐Markovnikov route in ene reactions of sterically encumbered nitrosocarbonyl intermediates in the presence of allylsilylethers. Fluoride‐mediated deprotection/cyclization of the ene adducts afforded the desired heterocycles in quantitative yields and the methodology is adaptable to a one‐pot procedure. [ABSTRACT FROM AUTHOR]

Enantioselective auto‐tandem catalysis represents a challenging yet highlight attractive topic in the field of asymmetric catalysis. In this context, we describe a dual catalytic cycle that merges allylic cyanation and asymmetric hydrocyanation. The one‐pot conversion of a broad array of allylic alcohols into their corresponding 1,3‐dinitriles proceeds in good yield with high enantioselectivity. The products are densely functionalized and can be easily transformed to chiral diamines, dinitriles, diesters, and piperidines. Mechanistic studies clearly support a novel sequential cyanation/hydrocyanation pathway. [ABSTRACT FROM AUTHOR]

It has been established that a cationic rhodium(I)/P‐phos complex catalyzes the asymmetric [2+2+2] cycloaddition of 1,6‐enynes with racemic secondary allylic alcohols to produce the corresponding chiral bicyclic cyclohexenes, possessing three stereogenic centers, as a single diastereomer with excellent ee values. Mechanistic experiments revealed that the present cycloaddition proceeds through the kinetic resolution of the racemic secondary allylic alcohols, in which one enantiomer preferentially reacts with the 1,6‐enyne. [ABSTRACT FROM AUTHOR]

Herein, we report a ruthenium‐catalyzed redox‐neutral α‐alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone‐type "carbanions" and active protons in a one‐pot reaction, and at the same time achieves the first Grignard‐type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols. [ABSTRACT FROM AUTHOR]

A photocatalytic E to Z isomerization of alkenes using an iridium photosensitizer under mild reaction conditions is disclosed. This method provides scalable and efficient access to Z‐cinnamyl ether and allylic alcohol derivatives in high yields with excellent stereoselectivity. Importantly, this method also provides a powerful strategy for the selective synthesis of Z‐magnolol and honokiol derivatives possessing potential biological activity. [ABSTRACT FROM AUTHOR]