Stereoselective Synthesis of δd-Selanyl Allylic Alcohols by Hydrozirconation of Propargyl Selenides

Hydrozirconation of propargyl selenides afford (E)-3-selanyl vinylzirconocenes chlorides 2. Intermediates 2 reacted with aldehydes to obtain d-selanyl allylic alcohols.

Bismuth Mediated Organic Reaction: A Convenient Method for the Synthesis of Allylic (Benzylic) Selenides and α-Organylselenocarbonyl Compounds in Aqueous Media

In the presence of BiCl3/Al or BiCl3/Fe, in THF-H2O, allylic (benzylic) bromides or α-bromoketones react with diorganyl diselenides to give allylic (benzylic) selenides orα-organylselenocarbonyl compounds respectively in moderate to good yields.

A Convenient Method for Chlorination in Allylic Position

A convenient method for the chlorination in allylic position was developed by using the aqueous solution of sodium hypochlorite(2%_5% active chlorine) and an acid as chlorination reagent in a diphase system. The method has the advantage of cheap reagents, mild reaction conditions and good yields. The quantity and the feeding rate of the chlorination reagent can be controlled easily. The method is particularly suitable for the chlorination in laboratories.

Synthesis of novel chiral phosphine-triazine ligand derived fromα-phenylethylamine for Pd-catalyzed asymmetric allylic alkylation

A novel chiral phosphine-triazine ligand was synthesized from chiral α-phenylethylamine through a three-step procedure. In a model reaction of Pd-catalyzed allylic alkylation of rac-1,3-diphenylprop-2-en-1-y1 pivalate with dimethyl malonate, good enantioselectivity （90% e.e.） was obtained by using this ligand.

Microwave-assisted Allylic Oxidation at C-13 Position of 14-Deoxysinenxan A

Microwave-assisted allylic oxidation at C-13 position of 14-deoxysinenxan A was described. This new method (150℃/10 min/5 bar on microwave synthesizer) led to a better yield of compound 1 and shorter reaction time.

Arylation of Allylic Alcohols with Aryl Iodides Catalyzed by a Silica-Bound Bidentate Sulfur Palladium (0) Complex

Allylic alcohols react with aryl iodides in the presence of tri-n-butylamine and a catalytic amount of a silica-bound bidentate sulfur palladium (0) complex to form 3-arylaldehydes or ketones in good yields.

Regioselective and asymmetric allylic alkylation of vinyl epoxides for the construction of allylic alcohols via synergistic catalysis

A highly efficient asymmetric allylic alkylation of cyclic and acyclic carbon nucleophiles with vinyl epoxides has been developed,which exhibits good functional group compatibility,high atomic and step economy.This protocol utilizes a strategy of synergistic catalysis with a chiral N,N'-dioxide/Ni~Ⅱ complex and an achiral Pd~0 catalyst,generating a series of multisubstituted allylic alcohols with a quaternary carbon stereocenter in high yield and excellent regio-,Z/E-and enantioselectivity under mild conditions.Further transformations of the product demonstrate the potential utility of this protocol in the synthesis of allyl alcohol derivatives and natural product analogues.Experimental studies revealed that the N,N′-dioxide/metal complexes play an important role in controlling the Z/E-and enantioselectivity.The density functional theory(DFT) calculations further demonstrated that multiple C–H···π interactions between the aromatic rings of the two substrates and the amide moiety in the ligand stabilized the dominant transition state.

Pd-Catalyzed Asymmetric Allylic C—H Functionalization

Comprehensive Summary Pd-catalyzed asymmetric allylic C—H functionalization has emerged as a powerful tool to access chiral,densely functionalized molecules from easily accessible alkenes,enabling the increase of the step-or atom-economy by minimizing functional group manipulations for preparing allylating reagents.Due to the inadequacy of stereoselection strategies,the asymmetric allylic C—H functionalization is still in the early stage.In this essay,we will describe our journey to identification of asymmetric catalytic systems,mechanism of allylic C—H activation,control of stereo-and regioselectivity,and applications in asymmetric synthesis.

Synergistic catalysis for stereocontrol of prochiral nucleophiles in palladium-catalyzed asymmetric allylic substitution

In contrast to the stereocontrol of the stereocenter at the allyl unit,the asymmetric induction of prochiral nucleophiles remains a challenge in Pd-catalyzed asymmetric allylic substitutions due to the remote distance between the chiral catalyst and the stereocenter established at prochiral nucleophile.Much effort has been devoted to solving this challenge through the elaborate design of chiral ligands.Recently,synergistic catalysis has gained increasing attention owing to its potential advantages over the traditional single palladium catalysis,such as improvement of reactivity and selectivity.This strategy,including bimetallic catalysis and Pd/organocatalysis,not only broadens the scope of prochiral nucleophiles,but also provides a simple and unified method for the stereocontrol of prochiral nucleophiles.This review summarizes the brief history and advances in this field.

Palladium-catalyzed allylic alkylation enabled by ketone umpolung via Pudovik addition/[1,2]-phospha-Brook rearrangement

Palladium-catalyzed allylic alkylation enabled by ketone umpolung via Pudovik addition/[1,2]-phospha-Brook rearrangement with phosphites has been developed.The protocol offers a straightforward method for the synthesis of potentially bioactive homoallylic alcohol phosphonates in an efficient and economical way.This cascade reaction proceeds under mild conditions with excellent functional group compatibility.Furthermore,the catalytic asymmetric version has also been explored.

Palladium-catalyzed annulative allylic alkylation for regioselective construction of indole-fused medium-sized cyclic etherS

A new palladium-catalyzed annulative allylic alkylation(AAA)reaction of 2-(indol-2-yl)phenols with dual allylic electrophiles such as isobutylene dicarbonate and butene dicarbonate is described,leading to the regioselective synthesis of tetracyclic medium-sized cyclic ethers possessing a bridged aryl-indole scaf-fold,namely,benzo[2,3]oxocino[4,5-b]indoles and benzo[2,3]oxepino[4,5-b]indoles,in good to excellent yields.This protocol demonstrates a broad substrate scope,good compatibility with substituents and high regioselectivity,providing a catalytic and flexible method for creating bridged aryl-indole skeletons.

Palladium-Catalyzed Asymmetric Allylic Alkylation/α-Iminol Rearrangement:A Facile Access to 2-Spirocyclic-Indoline Derivatives

We report an unprecedented Pd-catalyzed asymmetric allylic alkylation of 1-(indol-2-yl)cyclobutanols followed by anα-iminol rearrangement.High yields with excellent chemo-,regio-,diastereo-,and enantioselectivities have been realized,affording a wide range of enantioenriched 2-spirocyclicindolines bearing two contiguous stereocenters.The facial selectivity of the ensuing rearrangement is controlled by the subtle difference of the substituents on the all-carbon quaternary stereogenic center formed in the allylic alkylation step.Nonactivated racemic terminal allylic alcohols are utilized as efficient electrophiles via kinetic resolution pathways for the first time in Pd-catalyzed asymmetric allylic alkylation.The role of Et3B additive is pivotal to activating allylic alcohols toward the formation of π-allylpalladium species and suppressing N/O allylic alkylation of indole with enhanced C3-nucleophilicity.Electrospray ionization high-resolution mass spectrometry(ESIHRMS)experiments provided strong evidence for the existence of the key nucleophilic boron anionic species,which fully accounts for the essential role of the Et_(3)B additive.The study of the mechanism indicates that the real catalytically active species is an electronic π-cinnamyl-palladium complex coordinated by two phosphoramidite ligands,which is consistent with the observed nonlinear effect and control experiments and is further confirmed by X-ray structure analysis.

Transition Metal-Catalyzed Allylic C(sp3)-H Functionalization via η3-Allylmetal Intermediate

1.Introduction The past few decades have witnessed extensive studies on transition metal-catalyzed C-H bond activations and subsequent carbon-carbon and/or carbon-heteroatom bond formations because these methods provide more atom-and step-economical pathways than those traditional transformations starting from prefunctionalized substrates.

Ligand-Controlled Copper-Catalyzed Highly Regioselective Difluoromethylation of Allylic Chlorides/Bromides and Propargyl Bromides

Highly regiodivergent copper-catalyzed allylic/propargylic difluoromethylation reactions by employing different ligands are described. When 5,6-dimethyl-1,10-phenanthroline was used as the ligand, exclusively α-difluoromethylated products were obtained, while γ-selective difluoromethylated products were generated when N-heterocyclic carbene-SIPr was used as the ligand. Likewise, high α- vs. γ-selectivities were achieved in the presence of similar copper catalysts for the reactions of propargyl bromides. Moreover, a copper-catalyzed asymmetric allylic difluoromethylation reaction with moderate to good enantioselectivity by the use of chiral ligands was developed.

CuCl-Catalyzed Aerobic Oxidation of Allylic and Propargylic Alcohols to Aldehydes or Ketones with 1 ： 1 Combination of Phenanthroline and Bipyridine as the Ligandst

We developed a modified protocol for the oxidation of 2,3-allenyl alcohols using CuCI with l ： 1 combination of phenanthroline and bipyridine as the catalyst. To further investigate the applicability of this system, other types of alcohols such as allylic and propargylic alcohols have been tested： we found that both allylic and propargylic alcohols may be oxidized to the corresponding aldehydes or ketones using molecular oxygen in air as the oxidant with moderate to excellent yields.

Enantioselective O-allylic alkylation of Morita-Baylis-Hillman carbonates with oxime

The enantioselective O-allylic alkylation of acetophenone oxime with various Morita-Baylis-Hillman (MBH) carbonates has been accomplished by the catalysis of a commercially available cinchona alkaloid (DHQD)2PHAL. The corresponding O-allylic products were obtained in moderate to excellent yields up to 96% ee.

Palladium-catalyzed asymmetric allylic C–H alkylation of 1,4-dienes and glycine Schiff bases

A highly regio-and enantioselective allylic C–H alkylation of 1,4-dienes with glycine Schiff bases has been established by chiral palladium-phosphoramidite catalysis. This reaction can proceed under mild conditions and tolerate a wide scope of 1,4-dienes,delivering structurally diverse chiral β-branched α-amino acid surrogates in moderate to high yields and with high levels of regio-, Z/E-, diastereo-and enantioselectivities.

Influence of the Metal Ions on the Allylic Rearrangement Reac- tion of 3,4,5,6-Tetrahydrophthalic Anhydride

To further investigate the influence of metal ions on the allylic rearrangement of 3,4,5,6-tetrahydrophthalic an- hydride during the hydrothermal reaction, metal ions such as manganese（Ⅱ）, zinc（Ⅱ） and cadmium（Ⅱ） have been employed in the synthesis, which leads to the formation of three new lamellar coordination polymers, [MnⅡs（μ3-OH）3（1-chec）（1,2-chedc）（2,3-chedc）2（H20）] （3Mn）, [ZnⅡs（μ3-OH）3（1-chec）（1,2-chedc）（2,3-chedc）2（H20）] （4Zn）, and [CdⅡ3（μ3-OH）2（1,2-chedc）2] （5Cd） （1-chec=cyclohexene-l-carboxylate, 1,2-chedc=cyclohexene-1,2- dicarboxylate, 2,3-chedc=cyclohexene-1,2-dicarboxylate）. Interestingly, the allylic rearrangement reaction is metal-dependent, which occurs only in 3Mn and 4Zn, resulting in the formation of one chiral carbon atom of the corresponding dicarboxylate ligands in both compounds. In addition, the magnetic property of compound 3Mn was studied, which revealed strong antiferromagnetic interactions between the metal centers.