Bimolecular reduction of carbon dioxide: double synthons for alkynes trifunctionalization

Carbon dioxide reduction, as a sustainable and versatile strategy for the access of chemical fuels, has attracted increasing attention and enormous efforts have been devoted to it in recent years. However, employing carbon dioxide as double synthons via bimolecular reduction remains challenging. Here, by leveraging the bimolecular reduction of carbon dioxide to carbonyl and methyl respectively, we describe a Pd-catalyzed trifunctionalization of alkynes with aryl iodide for the first time and showcase its advantages on the formation of various β-diketones and their application in the constructing of heterocyclic compounds with important biological activity, including pyrimidine, oxazole, pyrazole.

Room-Temperature Electroreductiveα-Alkylation of N-Heteroarenes with Styrenes

Despite their interesting applications,direct and diverse syntheses of aryl-fused 2-alkyl cyclic amines still remain challenging.Here,the concept of incorporating a C–C coupling process into the N-heteroaryl reduction was successfully applied to fulfill such a synthetic purpose.Due to our use of controllable electroreduction coupled with proton abstraction,we can report a room-temperature reductiveα-alkylation of the inert N-heteroarenes with abundantly available styrenes in an undivided Zn(+)/C(−)cell.This proceeds with good substrate compatibility and operational simplicity,utilizes cost-effective sacrificial Zn-anode,exhibits high selectivity,and does not need pressurized H2 gas and transition-metal catalysts.This current work offers a useful platform for direct construction of valuable aryl-fused 2-alkyl cyclic amines that are difficult to access with conventional methods.

Copper-Catalyzed Benzylic C—H Functionalization, Oxidation and Cyclization of Methylarenes: Direct Access to z-Arylbenzothiazoles

Background and Originality Content As an inexpensive,fundamental and important feedstock for the petrochemical industry,methylarenes have long been regarded as one of the most widely used raw materials for a great variety of organic transformations.Therefore,the selective benzylic C(sp3)—H functionalization is particularly important,which provides a strategic means to utilize this resource.

Palladium-catalyzed regioselective cascade reaction of carbon dioxide,amines and allenes for the synthesis of functionalized carbamates

A palladium-catalyzed regioselective three-component cascade reaction of carbon dioxide,amines and allenes has been developed,providing an expedient and practical method for the construction of a range of functionalized carbamates containing dihydrobenzofuran or indole moiety in moderate to excellent yields.The broad substrate scope,good functional group tolerance and excellent chemo-and regioselectivity are the features of the transformation.

Steric-switched defluorofunctionalization selectivity: controlled synthesis of monofluoroalkene-masked medium-sized heterocyclic lactams and lactones

The steric-switched ipso-defluoroamination-triggered and ipso-defluorooxylation-triggered cyclization of(trifluoromethyl)alkenes with amino alcohols and diamines are achieved under mild conditions. This regioselective strategy distinguishes the different nucleophilic heteroatom sites in amino alcohols and unsymmetric diamines by the sequential defluorinative functionalization of two C(sp^(3))–F bonds in a CF_(3) group. Various attractive monofluoroalkene-masked medium-sized heterocyclic lactams and lactones are obtained in moderate to excellent yields. Simple derivation of these masked-heterocycles efficiently affords useful skeletons of lactams, lactones, and 1,4-oxazepanes in a single diastereoisomer. Mechanism studies indicate that a unique sequential ipso-/γ-selective defluorinative functionalization pathway is involved in these transformations.

Palladium-Catalyzed Intermolecular Oxidative Coupling Reactions of （Z）-Enamines with Isocyanides through Selective β-C（sp2）-H and/or C = C Bond Cleavage

Herein, two efficient palladium-catalyzed intermolecular oxidative coupling reactions of （Z）-enamines with isocyanides via selective β-C（sp2）-H and/or C=C bond cleavage have been developed, leading to controllable chemodivergent and stereoselective construction of a wide range of （E）-β-carbamoylenamine derivatives containing strong intramolecular hydrogen bonds. Furthermore, possible reaction pathways for these transfor- mations are proposed on the basis of preliminary mechanism studies.

Direct C(sp^(3))-H Sulfonylation of Xanthene Derivatives with Sodium Sulfinates by Oxidative Copper Catalysis

By employing a readily available CuCI/DDQ catalyst system,we herein report a direct C(sp^(3))-H sulfonylation of xanthene derivates with odorless sodium sulfinates.Various 9H-xanthenes,thioxanthenes,and 9,10-dihydroacridines are efficiently transformed into the desired benzylic sulfonyl products via a radical/radical cross-coupling process,proceeding with the merits of broad substrate scope,operational simplicity,good functional group compatibility,and mild reaction conditions.

Silver-Catalyzed Three-Component Coupling of Carbon Dioxide, Amines and α-Diazoesters

A silver-catalyzed three-component coupling reaction of carbon dioxide, amines and α-diazoesters has been developed for the first time. The novel reaction provides an efficient and practical methodology for the synthesis of a wide range of new α-carbamoyloxy esters, which are difficult to prepare by existing methods. The advantages of the method include the use of readily available starting materials, simple catalytic system, good atom economy and high functional group tolerance.

Synergy of activating substrate and introducing C–H…O interaction to achieve Rh2(II)-catalyzed asymmetric cycloisomerization of 1,n-enynes

We report the first Rh2(II)-catalyzed asymmetric cycloisomerization of activated enynes to provide cyclopropane-fused tetrahydropyridines in good yields and excellent enantioselectivities under mild conditions.The activated group,CHZ(Z is electronwithdrawing group(EWG)),in the enyne substrates exerts two synergetic roles,one is to activate alkyne for the cyclopropanation reaction;the other is to introduce the C–H…O interaction between substrate and catalyst(reducing the energy barrier of the reaction).This double-mode activation was supported by both density functional theory(DFT)calculations and experimental tests.This strategy was also extended to other CH2 Z(Z can be OH,OMe,F)as activating groups that made the CH2 more acidic so that the substrates could also form increased C–H…O interaction with the catalyst.

Synthesis of acridinones via palladium-catalyzed reductive annulation of 2-nitrobenzaldehydes and resorcinols

The catalytic conversion of biomass-derived feedstocks into functional molecules is of significance to synthetic organic chemistry.Herein,through a palladium-catalyzed reductive annulation reaction of resorcinols and 2-nitrobenzaldehydes,we present a new approach for the direct synthesis of acridinone derivatives,featuring operational simplicity,good substrate compatibility,and readily available feedstocks.