Regio- and Stereoselective Copper-Catalyzed Allylation of 1,3-Dicarbonyl Compounds with Terminal Allenes

Chemo- and Regioselectivity in Allenamide-Homoenolate Coupling

We report herein a chelation assisted, ring-strain-driven homoenolate interception with allenamides, proceeding through a complementary reactivity pattern─noncycloaddition and central C interception of C-pronucleophiles─distinct from previous studies. The developed atom-economical method provides access to carbonyl-tagged enamides with high chemo- and regioselectivity, offering a broad scope and significant synthetic value, as demonstrated by further diversification. The origin of the selectivity is clarified through experimental mechanistic investigations, revealing the detailed reaction pathway proceeding through a carbopalladation event.

Synthesis of 1,3-Dicarbonyl Azepines via Photoinitiated Reactions of Aryl Azides with Carbon-Based Nucleophiles

A photoinduced one-pot method for the synthesis of azepines by the reaction of aryl azides with 1,3-dicarbonyl compounds under weakly basic conditions is described. This method offers a simple route for the synthesis of 1,3-dicarbonyl-substituted azepines in good to excellent yields and high regioselectivity and was tested on 1,3-dicarbonyl compounds with different acidity levels. The resulting azepines have electrophilic and nucleophilic centers of varying degrees of activity, which facilitate reactions leading to further structural transformations.

Metal free regio - and stereoselective semireduction of CF3-substituted N-allenamides

We developed a chemoselective metal-free access for the 1,2- and 2,3-semireduction of CF3-N-allenamides. The enamide functionality of CF3-substituted N-allenamides could be efficiently reduced by Et3SiH/BF3·OEt2 in total regioselectivity and good stereoselectivity, whereas DBU promoted the isomerization of the resulting allyl amide leading exclusively to the E-configurated enamide.

Regio- and diastereoselective transition metal-free hydroalkylation of N-allenyl sulfonamides by push-pull 2-alkynylquinolines

We describe a novel and efficient synthetic strategy to construct the linear homoallylic quinolone structures through the intermolecular addition of 2-alkynylquinoline to N-allenyl sulfonamides. We developed the regio- and diastereoselective transition metal-free hydroalkylation of 1,2-dienes by a structure containing a push-pull system. Moreover, the present work was carried out with a high atom economy, mild reaction conditions, and moderate to high yields.

Copper-Catalyzed Decarboxylative Cascade Cyclization of Propargylic Cyclic Carbonates/Carbamates with Pyridinium 1,4-Zwitterionic Thiolates to Fused Polyheterocyclic Structures

A copper-catalyzed decarboxylative cascade cyclization of propargylic cyclic carbonates/carbamates with pyridinium 1,4-zwitterionic thiolates is developed. A range of fused polyheterocyclic compounds are obtained in moderate to good yields with excellent diastereoselectivities. Of particular note is that four new bonds (two C-C, one C-O/N, one C-S) and four new stereocenters could be efficiently embedded into the tetracyclic fused scaffolds in a single step.

Palladium-catalyzed regioselective hydrosulfonylation of allenes with sulfinic acids

An atom-economic method of preparing allylic sulfones via hydrosulfonylation of allenes with sulfinic acids under Pd(0)-catalysis was reported. This process has a high degree of regio- and stereoselectivity, and provides the target product with a moderate to excellent yield. A wide range of nitrogen- or oxygen-containing linear E-allylic sulfones have been synthesized. With the support of experimental research, a possible mechanism was proposed.

Cobalt-catalyzed regiodivergent hydrofunctionalization of allenes

A regiodivergent cobalt-catalyzed addition of carboxylic acid or 1,3-dicarbonyl compounds to allenes has been developed to prepare E-enol esters and allylation products.

Synergistic Copper/Enamine Catalysis for the Regio-, Stereo-, and Enantioselective Intermolecular α-Addition of Aldehydes to Allenamides

We herein describe an intermolecular enantioselective α-addition of aldehydes to allenamides using a dual copper/enamine catalytic system. Highly enantioselective addition of aldehydes was obtained thanks to secondary amine catalysts. The process was found to be highly regio-, stereo-, and enantioselective under mild conditions.

Copper-Catalyzed Synthesis of Terminal vs. Fluorine-Substituted N-Allenamides via Addition of Diazo Compounds to Terminal Ynamides

A copper-mediated coupling reaction between ynamides and diazo-compounds to produce N-allenamides is reported for the first time. This method enables facile and rapid access to terminal N-allenamides by using commercially available TMS-diazomethane with wide functional group compatibility on the nitrogen. Furthermore, the ubiquity of molecules containing a fluorine moiety in medicine, in agricultural, and material science requires the continuous search of new building blocks, including this unique surrogate. The CuI/diazo protocol was successfully applied to the synthesis of fluorine-substituted N-allenamides. DFT calculations provided insights in the mechanism involved.

Easy Access to Allylic Sulfones Through Transition-Metal-Free Hydrosulfonylation Of Allenes

A Brønsted acid-mediated addition of (hetero)aryl and (cyclo)alkyl sodium sulfinates to N-allenyl derivatives, which proceeds in water, is described under very smooth conditions. This reaction provided a practical and efficient protocol for the regio- and stereoselective synthesis of allylic sulfones in an atom- and step-economic fashion.

Palladium-Catalyzed Asymmetric Decarboxylative Addition of β-Keto Acids to Heteroatom-Substituted Allenes

The Pd-catalyzed asymmetric addition reaction of β-keto acids to heteroatom-substituted allene is reported. This reaction generates β-substituted ketones in an asymmetric manner through a branch-selective decarboxylative allylation pathway. The reaction accommodates various alkoxyallenes as well as amidoallenes.

Dual catalytic enantioselective desymmetrization of allene-tethered cyclohexanones

The construction of enantioenriched azabicyclo[3.3.1]nonan-6-one heterocycles via an enantioselective desymmetrization of allene-linked cyclohexanones, enabled through a dual catalytic system, that provides synchronous activation of the cyclohexanone with a chiral prolinamide and the allene with a copper(i) co-catalyst to deliver the stereodefined bicyclic core, is described. Successful application to oxygen analogues was also achieved, thereby providing a new enantioselective synthetic entry to architecturally complex bicyclic ethereal frameworks. The mechanistic pathway and the origin of enantio- and diastereoselectivities has been uncovered using density functional theory (DFT) calculations.

Synthesis of α-CF3-substituted E-dehydroornithine derivatives via copper(i)-catalyzed hydroamination of allenes

Novel α-CF₃-substituted E-dehydroornithine derivatives have been synthesized via the Cu(i)-catalyzed hydroamination of α-CF₃-α-allenyl-α-aminocarboxylates/phosphonates with different amines.

Synthesis of 1,4,5,6-tetrahydropyridazines and pyridazines via transition-metal-free (4 + 2) cycloaddition of alkoxyallenes with 1,2-diaza-1,3-dienes

We developed an economical and practical protocol for the synthesis of 1,4,5,6-tetrahydropyridazines. A diverse range of alkoxyallenes and 1,2-diaza-1,3-dienes undergo (4 + 2) cycloaddition to generate the desired products in excellent yields. The high efficiency, wide substrate scope and good functional group tolerance of this process, coupled with operational simplicity, render the method synthetically attractive. The utility of the cycloaddition is also demonstrated by the preparation of various pyridazines from 1,4,5,6-tetrahydropyridazines.

We developed an economical and practical protocol for the synthesis of 1,4,5,6-tetrahydropyridazines and pyridazines via cyclization of alkoxyallenes and 1,2-diaza-1,3-dienes.

Silica Surface Modification and Its Application in Permanent Link with Nucleic Acids

In this paper, the Pt-catalyzed hydrosilylation of hydroxyl ethers is described. Various bifunctional alkoxysilanes were obtained and applied in O-silylation of free hydroxyl groups on the silica surface. These modified solid materials have been used as excellent supports for linking synthetic nucleic acids. Nucleic acids permanently attached to the solid surface were tested in hybridization with complementary fluorescence-labeled sequences. Detection of nucleic acids anchored to the solid support was performed by fluorescence microscopy after hybridization.

Nickel catalyzed regio- and stereoselective arylation and methylation of allenamides via coupling reactions. An experimental and computational study

A novel Ni-catalyzed regio- and stereoselective condensation of boronic acids/Me₂Zn to allenamides is documented and its potential explored.