Asymmetric Allylic Reaction Research Articles

Dearomative [4 + 2] Cycloaddition of Pyridine via Energy-Transfer Catalysis

In this issue of Chem, Glorius and coworkers report the first photocatalytic dearomative cycloaddition of pyridine with alkene. High-value isoquinuclidines could be easily assembled from N-cinamoyl picolinamides under mild and operationally simple conditions.

Diastereo- and Enantioselective Synthesis of (E)-δ-Boryl-Substituted anti-Homoallylic Alcohols in Two Steps from Terminal Alkynes.

We report the highly diastereo- and enantioselective preparation of (E)-δ-boryl-substituted anti-homoallylic alcohols in two steps from terminal alkynes. This method consists of a cobalt(II)-catalyzed 1,1-diboration reaction of terminal alkynes with B2 pin2 and a palladium(I)-mediated asymmetric allylation reaction of the resulting 1,1-di(boryl)alk-1-enes with aldehydes in the presence of a chiral phosphoric acid. Propyne, which is produced as the byproduct during petroleum refining, could be used as the starting material to construct homoallylic alcohols that are otherwise difficult to synthesize with high stereocontrol.

Diastereo‐ and Enantioselective Synthesis of (E)‐δ‐Boryl‐Substituted anti‐Homoallylic Alcohols in Two Steps from Terminal Alkynes

AbstractWe report the highly diastereo‐ and enantioselective preparation of (E)‐δ‐boryl‐substituted anti‐homoallylic alcohols in two steps from terminal alkynes. This method consists of a cobalt(II)‐catalyzed 1,1‐diboration reaction of terminal alkynes with B2pin2 and a palladium(I)‐mediated asymmetric allylation reaction of the resulting 1,1‐di(boryl)alk‐1‐enes with aldehydes in the presence of a chiral phosphoric acid. Propyne, which is produced as the byproduct during petroleum refining, could be used as the starting material to construct homoallylic alcohols that are otherwise difficult to synthesize with high stereocontrol.

Amide Enolate Surrogates in Asymmetric Allylation Reactions

Amide Enolate Surrogates in Asymmetric Allylation Reactions

First Stereoselective Total Synthesis of (3S,7R)-De-O-methylbotryosphaeriodiplodin

A simple and highly efficient first stereoselective total synthesis of a benzofused macrocyclic lactone, ( 3S,7R)-de- O-methylbotryosphaeriodiplodin has been accomplished utilizing Jacobson's kinetic resolution, Marouka asymmetric allylation, Stille coupling, and ring-closing metathesis (RCM) reactions as key steps.

Pd-catalyzed asymmetric allylic substitution cascade using α-(pyridin-1-yl)-acetamides formed in situ as nucleophiles.

A Pd-catalyzed asymmetric allylic substitution cascade reaction, using α-(pyridin-1-yl)-acetamides (formed in situ) as nucleophiles, has been developed, generating chiral piperidine-containing amino acid derivatives via a one-pot procedure in high yields and with up to 96% ee. The products can be easily converted into potential bioactive compounds, unnatural chiral amino acids and dipeptides.

惰性烯丙基试剂参与的不对称烯丙基化反应研究进展

惰性烯丙基试剂参与的不对称烯丙基化反应研究进展

Iridium‐Catalyzed Intramolecular Asymmetric Allylic Dearomatization of Benzene Derivatives

AbstractGuided by the mechanistic insights from computational studies, we have developed an Ir‐catalyzed asymmetric intramolecular allylic dearomatization reaction of benzene derivatives. Under the optimized conditions consisting of a readily available Ir catalyst, a series of spiro[4.5]cyclohexadiene compounds were delivered in reasonable yields (up to 79 %) with good enantioselectivity (up to 99 % ee). The introduction of a malonate diester‐type substituent serves as a key strategy to guide the nucleophilic reactivity of the benzene ring.

Iridium-Catalyzed Intramolecular Asymmetric Allylic Dearomatization of Benzene Derivatives.

Guided by the mechanistic insights from computational studies, we have developed an Ir-catalyzed asymmetric intramolecular allylic dearomatization reaction of benzene derivatives. Under the optimized conditions consisting of a readily available Ir catalyst, a series of spiro[4.5]cyclohexadiene compounds were delivered in reasonable yields (up to 79 %) with good enantioselectivity (up to 99 % ee). The introduction of a malonate diester-type substituent serves as a key strategy to guide the nucleophilic reactivity of the benzene ring.

Stereoselective synthesis of the C3-C15 fragment of callyspongiolide

The synthesis of C3-C15 fragment of callyspongiolide, a 14-membered macrolides isolated from the marine sponge Callyspongia sp., which was collected from the Indonesia, is reported. Highlights of the synthesis include construction of E-olefin through Julia-Kocienski olefination, Brown asymmetric allylation and base-induced elimination reactions for propargyl alcohol synthesis.

α-Quaternary Chiral Aldehydes from Styrenes, Allylic Alcohols, and Syngas via Multi-catalyst Relay Catalysis

Summary Mimicking the way nature synthesizes organic molecules, multi-catalyst relay catalysis (MCRC), based on the seamless combination of a series of catalytic reactions, has emerged as a promising strategy for achieving ideal synthesis. In such systems, each step takes place orderly and sequentially. Taken as a whole, the entire process appears indistinguishable from a common one-step reaction but provides a means for extraordinary transformations. Here, we report a one-step transformation of styrenes, allylic alcohols, and syngas to α-quaternary chiral aldehydes in a multi-catalyst system consisting of a rhodium(I) complex, a palladium(0) complex, a chiral Bronsted acid catalyst, and an achiral amine (20–100 mol %). The cascade hydroformylation and asymmetric allylation reaction was realized with high yields (up to 98%) and high enantioselectivities (up to 99% ee) under mild conditions (1 bar of syngas).

A Brønsted acid-promoted asymmetric intramolecular allylic amination of alcohols.

Reported herein is a chiral Brønsted acid-catalyzed asymmetric intramolecular allylic amination reaction, allowing facile access to a range of biologically interesting chiral 2-substituted hydroquinolines in up to 90% yield and with up to 93% ee. Furthermore, a significant effect of an N-protecting group was observed in this asymmetric process.

Asymmetric Allylation of Carbonyl Compounds Catalyzed by a Chiral Phosphine–Silver Complex

A catalytic, asymmetric allylation reaction of aldehydes or ketones with allyltrimethoxysilane was achieved by using a BINAP·AgBF4 [BINAP = 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl] complex as the chiral precatalyst and triethylamine as the base precatalyst in the presence of 2,2,2‐trifluoroethanol. Optically active homoallylic alcohols with up to 95 % ee were obtained in moderate to high yields through the in situ generated chiral allyl silver catalyst.

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.

Asymmetric Allylation of Furfural Derivatives: Synergistic Effect of Chiral Ligand and Organocatalyst on Stereochemical Control

An asymmetric allylation reaction at the benzylic position of furfurals that are easily accessed from 5-HMF, which is a biomass derivative, has been established by palladium and amine cooperative catalysis. The high levels of enantioselectivity of up to 97% enantiometric excess (ee) were enabled by the synergistic stereochemical control of a chiral TADDOL-based phosphoramidite ligand and a chiral diphenylprolinol silyl ether. The product could be feasibly transformed to chiral aryl-substituted spiroacetal via a four-step reaction sequence.

Direct, Mild, and General n-Bu4NBr-Catalyzed Aldehyde Allylsilylation with Allyl Chlorides.

A direct, mild, and general method for the enantioselective allylsilylation of aldehydes with allyl chlorides is reported. The reactions are effectively catalyzed by 5 mol % of n-Bu4NBr, and this rate acceleration allows the use of complex allyl donors in fragment-coupling reactions and of electron-deficient allyl donors. The results are (1) significant progress toward a "universal" asymmetric aldehyde allylation reaction that can reliably and highly stereoselectively couple any allyl chloride_aldehyde combination and (2) the discovery of a novel mode of nucleophilic catalysis for aldehyde allylsilylation reactions.

Palladium‐Catalyzed Cascade sp2 C−H Functionalization/Intramolecular Asymmetric Allylation: From Aryl Ureas and 1,3‐Dienes to Chiral Indolines

AbstractA chiral PdII‐catalyzed cascade sp2 C−H functionalization/intramolecular asymmetric allylation reaction is reported. A new chiral sulfoxide–oxazoline (SOX) ligand bearing single chiral center on the sulfur was identified as the optimal ligand for the reaction, being efficient both in the C−H cleavage step and the stereocontrol of the allylation step. The broad scope of this method with respect to aryl ureas and 1,3‐dienes enables the rapid construction of valuable chiral indoline derivatives with high yields and enantioselectivities (up to 99 % yield, up to 95:5 e.r.).

Palladium-Catalyzed Cascade sp2 C-H Functionalization/Intramolecular Asymmetric Allylation: From Aryl Ureas and 1,3-Dienes to Chiral Indolines.

A chiral PdII -catalyzed cascade sp2 C-H functionalization/intramolecular asymmetric allylation reaction is reported. A new chiral sulfoxide-oxazoline (SOX) ligand bearing single chiral center on the sulfur was identified as the optimal ligand for the reaction, being efficient both in the C-H cleavage step and the stereocontrol of the allylation step. The broad scope of this method with respect to aryl ureas and 1,3-dienes enables the rapid construction of valuable chiral indoline derivatives with high yields and enantioselectivities (up to 99 % yield, up to 95:5 e.r.).

Iridium‐Catalyzed Intramolecular Asymmetric Allylic Dearomatization Reaction of Benzoxazoles, Benzothiazoles, and Benzimidazoles

AbstractAn iridium‐catalyzed intramolecular asymmetric allylic dearomatization reaction of benzoxazoles, benzothiazoles, and benzimidazoles was developed. The reaction was found to be compatible with a wide range of five‐membered‐ring electron‐deficient heteroaromatic compounds and furnished the corresponding dearomatized heterocycles in high yield with excellent enantioselectivity.

Iridium-Catalyzed Intramolecular Asymmetric Allylic Dearomatization Reaction of Benzoxazoles, Benzothiazoles, and Benzimidazoles.

An iridium-catalyzed intramolecular asymmetric allylic dearomatization reaction of benzoxazoles, benzothiazoles, and benzimidazoles was developed. The reaction was found to be compatible with a wide range of five-membered-ring electron-deficient heteroaromatic compounds and furnished the corresponding dearomatized heterocycles in high yield with excellent enantioselectivity.