Search

The electrochemical cross-coupling of aryl bromides and arylamines catalyzed by nickel/bipyridine complexes was explored using density functional theory (DFT) calculations. The steric and electronic effects on the catalyst were further analyzed.

The in situ generated imine was cross-coupled with cyanopyridine to synthesize diarylmethylamine via cathodic reduction under electrochemical conditions.

The one-pot coupling of arylammonium salts and secondary phosphines from the in situ reduction of diarylphosphine oxides via SNAr reaction for the transition-metal-free synthesis of triarylphosphines is reported.

The cost-efficient development of an α-chiral pyrrolidine library is achieved via a rapid continuous flow protocol under mild conditions.

An electrochemical protocol for the direct oxidation of both arenes and heteroarenes to quinones under mild conditions was developed.

A continuous flow process for the preparation of betahistine with a 90% isolated yield has been reported. 2-Vinylpyridine and saturated methylamine hydrochloride aqueous solution were used as start...

3-Methyl-5-benzofuranol was prepared by a one-pot process from morpholine, propionaldehyde, and p-benzoquinone in 85–87% isolated yields. Avoiding the tedious multistep isolation and purification o...

Regioselective and diastereodivergent asymmetric vinylogous Michael addition (AVMA) between β-substituted-cyclohexenones and nitroalkenes via dienamine activation under complementary chiral aminocatalysts was reported. γ-Regioselective AVMA of β-alkyl-cyclohex-2-enones via a linear exo-dienamine mechanism and γ′-regioselective functionalization of β-substituted-cyclohex-3-enones via a cyclic extended endo-dienamine mechanism were reported in satisfactory yields with high enantio- and diastereoselectivities. DFT calculations reasonably explained that the diastereoselectivity of the reactions at the γ- and γ′-positions is achieved by regulating the orientation of the nitroalkenes through the hydrogen-bonding interaction and steric hindrance effect. Furthermore, the four different configurations of the γ- and γ′-adducts were diversified to the corresponding enantioenriched spirocyclic ketones and cis-2-decalones with multiple chiral centers.

The laboratory experiment regarding esterification of ethylene glycol with acetic acid to ethylene glycol diacetate using resin catalysts in a continuous flow was designed to carry out the reaction in a flow through an inquiry-guided approach. Incorporating the burgeoning field of continuous flow chemistry into the educational infrastructure, the experiment showed the practical application of heterogeneous catalysts in continuous flow synthesis. In a discussion of the importance of continuous flow chemistry and heterogeneous catalysis, students were encouraged to seek effective, sustainable, and environmentally friendly approaches to synthesize compounds.

2-Pyridyl ketones widely appear in bioactive molecules, natural products, and are employed as precursors of chiral 2-pyridine alky/aryl alcohols or 2-aminoalkyl pyridine ligands for asymmetric catalysis. Herein, a practical method for the rapid synthesis of 2-pyridyl ketone library in continuous flow is reported, in which the 2-lithiopyridine formed by Br/Li exchange reacts with commercially available esters to obtain 2-pyridyl ketones in a good yield at short reaction time. This protocol functions broadly on a variety of esters and has been applied to the synthesis of TGF-β type 1 receptor inhibitor LY580276 intermediate in an environmentally friendly method. It is rapid, reliable, and cost-efficient to afford diverse kinds of 2-pyridyl ketones in the compound library.

A practical continuous flow protocol has been developed using readily accessible

We develop an electrochemical nickel-catalyzed aminomethylation of aryl bromides under mild conditions. The convergent paired electrolysis makes full use of anode and cathode processes, free of a terminal oxidant, a sacrificial anode, a metal reductant, and a prefunctionalized radical precursor. In addition, this method exhibits wide functional group tolerance (63 examples), including some sensitive substituents and aromatic heterocycles. This redox neutral cross coupling provides a more environmentally friendly and synthetic practical protocol for forging C(sp

By merging electricity with sulfate, the Ritter-type amination of C(sp

Variable-temperature 15N solid-state NMR spectroscopy is used to uncover the dynamics of three diamines appended to the metal-organic framework Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate), an important family of CO2 capture materials. The results imply both bound and free amine nitrogen environments exist when diamines are coordinated to the framework open Mg2+ sites. There are rapid exchanges between two nitrogen environments for all three diamines, the rates and energetics of which are quantified by 15N solid-state NMR data and corroborated by density functional theory calculations and molecular dynamics simulations. The activation energy for the exchange provides a measure of the metal-amine bond strength. The unexpected negative correlation between the metal-amine bond strength and CO2 adsorption step pressure reveals that metal-amine bond strength is not the only important factor in determining the CO2 adsorption properties of diamine-appended Mg2(dobpdc) metal-organic frameworks.

A metal-free convergent paired electrolysis strategy to synthesize benzylic amines through direct arylation of tertiary amines and benzonitrile derivatives at room temperature has been developed. This TEMPO-mediated electrocatalytic reaction makes full use of both anodic oxidation and cathodic reduction without metals or stoichiometric oxidants, thus showing great potential and advantages for practical synthesis. This convergent paired electrolysis method provides a straightforward and powerful means to activate C-H bonds and realize cross-coupling with cathodically generated species.

We report the first electrochemical strategy to synthesize functionalized naphthalene derivatives through [4+2] annulation-rearrangement-aromatization from styrenes under mild conditions. The electrolysis does not require metals, oxidants and high valence substrates, indicating the atom and step-economy ideals. The dehydrodimer produced through [4+2] cycloaddition of 4-methoxy α-methyl styrene is isolated and proved to be the key intermediate for the following oxydehydrogenation to form carbon cation, which undergoes rearrangement-aromatization to afford the final products. This reaction represents a powerful access to construct multi-substituted naphthalene blocks in a single step.

The asymmetric Michael reaction of 3(2H) furanones and α,β-unsaturated ketones was investigated, with the employment of a bulky chiral primary amine. The protocol afforded a series of substituted furanone derivatives in a highly diastereo- (>30 : 1 dr) and enantioselective (up to 93% ee) manner with generally good to excellent yields (up to 99%).

Transition-metal-free visible-light photoredox catalyzed decarboxylative radical addition has been developed for the construction of α,β-diamino esters from amino acids with glyoxylic oxime ethers under mild conditions. Cyclic and chain amino acids, dipeptides, and simple aliphatic acids are amenable to this addition as the alkyl radical source. A variety of α,β-diamino esters with broad functional groups were synthesized in satisfactory yields at room temperature. The employment of acridinium as the photocatalyst and its potential scalability also demonstrate the synthetic value in practice.

An effective aza-Mannich reaction between olefinic rhodanines/hydantoins and N-Boc aminals catalyzed by Bronsted acid has been developed. Multifunctional rhodanine/hydantoin derivatives were obtained in 71–86% yields and an up to 95/5 Z/E ratio under mild conditions.

A convenient method mediated by photoredox catalysis for the direct construction of 1,4-dicarbonyl compounds has been developed. Simple aromatic symmetric carboxylic anhydrides or mixed anhydrides (generated in situ) have been utilized as an acyl radical source in addition to different types of Michael acceptors. A wide range of substrates are amenable to this new type of acyl Michael addition under mild conditions with broad functional group tolerance. As an application, a novel four-step synthesis of medicinal agent haloperidol is also presented.

Metal–organic frameworks that flex to undergo structural phase changes upon gas adsorption are promising materials for gas storage and separations, and achieving synthetic control over the pressure at which these changes occur is crucial to the design of such materials for specific applications. To this end, a new family of materials based on the flexible metal–organic framework Co(bdp) (bdp2– = 1,4-benzenedipyrazolate) has been prepared via the introduction of fluorine, deuterium, and methyl functional groups on the bdp2– ligand, namely, Co(F-bdp), Co(p-F2-bdp), Co(o-F2-bdp), Co(D4-bdp), and Co(p-Me2-bdp). These frameworks are isoreticular to the parent framework and exhibit similar structural flexibility, transitioning from a low-porosity, collapsed phase to high-porosity, expanded phases with increasing gas pressure. Powder X-ray diffraction studies reveal that fluorination of the aryl ring disrupts edge-to-face π–π interactions, which work to stabilize the collapsed phase at low gas pressures, while d...

Variable-temperature (15)N solid-state NMR (SSNMR) spectroscopy is used to investigate the dynamics of three diamines within the pores of the metal–organic framework Mg(2)(dobpdc), which exhibit both bound and free nitrogen environments when coordinated to the framework open metal sites. From these experiments it is possible to quantify the rates and energetics for exchange between the two nitrogen environments, and the results can then be corroborated by density functional theory calculations and molecular dynamics simulations. The activation energy for the exchange also enables quantification of the metal–amine bond strength, which is correlated with the CO(2) adsorption properties of the diamine-appended frameworks.

The chiral primary amine catalyzed asymmetric Michael reaction of thiazolones and α,β-unsaturated ketones was reported. Two different optimal catalytic systems were obtained corresponding to cyclic and linear α,β-unsaturated ketones. By employing chiral primary amines as the catalysts and amino-acid derivatives as the additives, a variety of Michael adducts containing the scaffold of the thiazole ring were prepared in moderate to good yields and with excellent diastereo- and enantioselectivities (up to 95% yield, all up to >19/1 dr, up to 96% ee). The reaction was scaled up to obtain 1.73 grams of the Michael adduct with the maintenance of yield and stereoselectivity.

A metal-free convergent paired electrolysis strategy to synthesize benzylic amines through direct arylation of tertiary amines and benzonitrile derivatives at room temperature has been developed. This TEMPO-mediated electrocatalytic reaction makes full use of both anodic oxidation and cathodic reduction without metals or stoichiometric oxidants, thus showing great potential and advantages for practical synthesis. This convergent paired electrolysis method provides a straightforward and powerful means to activate C-H bonds and realize cross-coupling with cathodically generated species.

The first example of organocatalyzed γ'-selective functionalization of cyclic enones with 3-substituted maleimides results in the stereoselective construction quaternary carbon center is presented. The reactions provided γ'-functionalized cyclic enones and β-functionalized cyclopentenones in good to excellent yields with excellent diastereo- and enantioselectivities. DFT calculations indicated that the reaction might proceed as a [4+2] cycloaddition/retro-Mannich reaction which could explain the unexpected product with a chiral quaternary carbon center and the excellent stereoselectivity.

Highly enantioselective 1,6-addition/1,4-addition cascade reactions between cyclic dienones and 2-indolnethiones have been realized by employing a cinchona-based primary amine catalyst. This method displays a broad substrate scope and provides a simple and highly effective way to achieve the chiral spiro[thiopyranoindole-cyclohexanone] scaffold.

We report herein a highly efficient intramolecular coupling reaction of tertiary amines and ketones (α,β-unsaturated ketones) by using a Brønsted acid as a cocatalyst, affording 2-arylindols in good to excellent yields (up to 92%) under visible light irradiation at room temperature.

An unprecedented remote construction of chiral vicinal tertiary and quaternary centers by a catalytic asymmetric 1,6-conjugate addition of prochiral carbon nucleophiles to cyclic dienones has been developed. Both 5H-oxazol-4-ones and 2-oxindoles were found to be very efficient carbon nucleophiles in this reaction at a remote position, giving products with excellent enantio- and diastereoselectivities (up to 99% ee and >19:1 d.r. for 5H-oxazol-4-ones and up to 97% ee and >19:1 d.r. for 2-oxindoles).

An array of organic bases DMAP (4-dimethylaminopyridine), DBU (1, 8-diazabicyclo [5.4.0] undec-7-ene), TBD (1, 5, 7-triazabicyclo [4.4.0] dec-5-ene), and their base/acid conjugate organocatalyst systems were evaluated in the trimerization of various isocyanates. The performance depended greatly on the combination of the catalyst systems, and the [HTBD][OAc] (acetic acid) catalyst systems were considerably the most active in contrast to the corresponding DMAP and DBU counterparts. The [HTBD][OAc] catalyst system was capable of providing isocyanurates from the cyclotrimerization of various isocyanate substrates in excellent yields in seconds even under bulk conditions. A bifunctional catalytic mechanism over [HTBD][OAc] was proposed.

An effective Friedel–Crafts reaction between N -Boc aminals and N -Boc indoles catalyzed by copper(II) trifluoromethanesulfonate has been developed. The less accessible N -Boc imines could be generated in situ from N -Boc aminals. The reaction was achieved in moderate to good yields under mild conditions.

Efficient synthesis of styrenyl enamides can be achieved from the corresponding 4-aryl-2-oxazolidinones, 2-thioxooxazolidines, and 2-thioxothiazolidines in the presence of the strong base lithium diisopropylamine. The reaction proceeded efficiently to achieve the enamides in good to excellent yields (up to 92%). This reaction provides an easy, rapid, and good-yielding method for the synthesis of styrenyl enamides.

An asymmetric doubly vinylogous Michael addition (DVMA) of α,β-unsaturated γ-butyrolactams to sterically congested β-substituted cyclic dienones with high site-, diastereo-, and enantioselectivity has been achieved. An unprecedented DVMA/vinylogous Michael addition/isomerization cascade reaction affords chiral fused tricyclic γ-lactams with four newly formed stereocenters.

Asymmetric formal aza-Diels–Alder reactions with α,β-unsaturated ketones and 3H-indoles with disubstituted groups on the C3 position catalyzed by primary amine-thiourea bifunctional catalyst have been developed. The reactions produced chiral hexahydropyrido-[1,2-a]-indole-2-ones in high yields with excellent diastereo- and enantioselectivities.

A diastereodivergent catalytic asymmetric Michael addition of 2-oxindoles to α,β-unsaturated ketones has been successfully developed with two complementary chiral diamine catalysts, affording chiral 3,3-disubstituted oxindoles with two adjacent chiral centers. Diastereodivergence has been realized through modifying substrates and utilizing different catalysts. Either anti-or syn-configured products possessing vicinal quaternary and tertiary stereogenic centers were produced with high enantioselectivities.