Synthesis of cyclic imides from nitriles and diols using hydrogen transfer as a substrate-activating strategy

Benzannulation with Et3N as 1,3-Diene Variants

With triethylamine as a 1,3-diene variant, a simple and practical process for the synthesis of phthalimides has been developed from readily available maleimide. The transformation can be performed in the absence of a metal catalyst with high levels of functional group tolerance. Various phthalimide compounds were constructed in moderate to good yields under mild conditions. Mechanism research indicates that oxygen and acid also play crucial roles in this reaction.

Direct Synthesis of Amides from Benzonitriles and Benzylic Alcohols via a KOt-Bu-Mediated MPV-type Hydrogen Transfer Process

Meerwein-Ponndorf-Verley (MPV)-type reduction between benzonitriles and benzylic alcohols under transition-metal-free conditions has been demonstrated for the first time. Using simple KOt-Bu as the base, various benzonitriles can be efficiently reduced by benzylic alcohols via hydrogen transfer reduction, and the resultant phenyl imine can react further with benzylic alcohols to give amides as the final product in which both the alcohols and the nitriles are incorporated. Preliminary mechanistic investigations indicated that the reaction may go through multiple MPV-type hydrogen transfer processes.

Palladium-Catalyzed Direct Dicarbonylation of Amines with Ethylene to Imides

The selective and effective conversion of low-cost and simple bulk chemicals into high value-added products through catalytic strategy has a wide range of practical significance. Here, a palladium-catalyzed method for the direct and efficient dicarbonylation of amines with basic industrial feedstock ethylene to imide has been developed. Moderate to excellent yields of the desired imides can be produced from readily available amines in a straightforward manner.

Synthesis and Identification of Epoxy Derivatives of 5-Methylhexahydroisoindole-1,3-dione and Biological Evaluation

Cyclic imides belong to a well-known class of organic compounds with various biological activities, promoting a great interest in compounds with this functional group. Due to the structural complexity of some molecules and their spectra, it is necessary to use several spectrometric methods associated with auxiliary tools, such as the theoretical calculation for the structural elucidation of complex structures. In this work, the synthesis of epoxy derivatives of 5-methylhexahydroisoindole-1,3-diones was carried out in five steps. Diels-Alder reaction of isoprene and maleic anhydride followed by reaction with m-anisidine afforded the amide (2). Esterification of amide (2) with methanol in the presence of sulfuric acid provided the ester (3) that cyclized in situ to give imides 4 and 4-ent. Epoxidation of 4 and 4-ent with meta-chloroperbenzoic acid (MCPBA) afforded 5a and 5b. The diastereomers were separated by silica gel flash column chromatography, and their structures were determined by analyses of the spectrometric methods. Their structures were confirmed by matching the calculated 1H and 13C NMR chemical shifts of (5a and 5b) with the experimental data of the diastereomers using MAE, CP3, and DP4 statistical analyses. Biological assays were carried out to evaluate the potential herbicide activity of the imides. Compounds 5a and 5b inhibited root growth of the weed Bidens pilosa by more than 70% at all the concentrations evaluated.

"On water" nano-Cu2O-catalyzed CO-free one-pot multicomponent cascade cyanation-annulation-aminolysis reaction toward phthalimides

An efficient nano-Cu2O-catalyzed cascade multicomponent reaction of 2-halobenzoic acids and trimethylsilyl cyanide with diverse amines was developed using water as a solvent, affording versatile N-substituted phthalimide derivatives in moderate to excellent yields. This novel strategy features carbon monoxide gas-free, environmentally benign, one-pot multistep transformation, commercially available reagents, a cheap catalyst without any additives, wide functional group tolerance, and operational convenience.

Tandem transformations and multicomponent reactions utilizing alcohols following dehydrogenation strategy

In this review, the progress of tandem transformation of nitro, nitrile and azide functionalities is summarised to develop new C–C and C–N bonds as well as multi-component reactions using alcohols.

Plasma-Triggered CH4/NH3 Coupling Reaction for Direct Synthesis of Liquid Nitrogen-Containing Organic Chemicals

Nitrogen-containing organic chemicals such as amines, amides, nitriles, and hydrazones are crucial in chemical and medical industries. This paper reports a direct synthesis of N,N-dimethyl cyanamide [(CH₃)₂NCN] and amino acetonitrile (NH₂CH₂CN) through a methane/ammonia (CH₄/NH₃) coupling reaction triggered by dielectric barrier discharge plasma, with by-products of hydrazine, amines, and hydrazones. The influence of CH₄/NH₃ molar ratio, feedstock residence time, and specific energy input on the CH₄/NH₃ plasma coupling reaction has been investigated and discussed. Under the optimized conditions, the productivities of (CH₃)₂NCN and NH₂CH₂CN reached 0.46 and 0.82 g·L^-1·h^-1, respectively, with 8.83% CH₄ conversion. In addition, through combining the optical emission spectra diagnosis and the reaction results, a possible CH₄/NH₃ plasma coupling reaction mechanism has been proposed. This paper provides a potential fine application of CH₄ and NH₃ in green synthesis of liquid nitrogen-containing organic chemicals, such as nitriles, amines, amides, and hydrazones.

Nickel-Catalyzed Transfer Hydrogenation of Benzonitriles with 2-Propanol and 1,4-Butanediol as the Hydrogen Source

The homogeneous transfer hydrogenation of benzonitrile with 2-propanol or 1,4-butanediol produced N-benzylidene benzylamine (BBA, 85% yield) using 5 mol % [Ni(COD)2] as a catalytic precursor and a mixture of Cy2P(CH2)2PCy2 and Cy2P(CH2)2P(O)Cy2 as ancillary ligands, under mild reaction conditions (120 °C, 96 h, tetrahydrofuran). 1,4-Butanediol performed better than 2-propanol as a hydrogen donor and yielded γ-butyrolactone as the product of transfer dehydrogenation. Selectivity toward dibenzylamine (DBA, 62% yield) was achieved by varying the amount of 1,4-butanediol in the catalytic system. A reaction mechanism was proposed, involving a ligand-assisted O-H bond activation, end-on substrate coordination, and a key dihydrido-Ni(II) intermediate, leading to the in situ formation of primary imines and amines to ultimately yield the secondary imines observed.

Ruthenium-catalyzed selective imine synthesis from nitriles and secondary alcohols under hydrogen acceptor- and base-free conditions

Ruthenium-catalyzed selective imine synthesis from nitriles and secondary alcohols under hydrogen acceptor- and base-free conditions was achieved.

Palladium-Catalyzed Hydroamidocarbonylation of Olefins to Imides

Carbonylation reactions allow the efficient synthesis of all kinds of carbonyl-containing compounds. Here, we report a straightforward synthesis of various imides from olefins and CO for the first time. The established hydroamidocarbonylation reaction affords imides in good yields (up to 90 %) and with good regioselectivity (up to 99:1) when applying different alkenes and amides. The synthetic potential of the method is highlighted by the synthesis of Aniracetam by intramolecular hydroamidocarbonylation.

Radical-mediated dehydrative preparation of cyclic imides using (NH4)2S2O8-DMSO: application to the synthesis of vernakalant

Ammonium persulfate–dimethyl sulfoxide (APS–DMSO) has been developed as an efficient and new dehydrating reagent for a convenient one-pot process for the synthesis of miscellaneous cyclic imides in high yields starting from readily available primary amines and cyclic anhydrides. A plausible radical mechanism involving DMSO has been proposed. The application of this facile one-pot imide forming process has been demonstrated for a practical synthesis of vernakalant.

Structure-based design of phthalimide derivatives as potential cyclooxygenase-2 (COX-2) inhibitors: anti-inflammatory and analgesic activities

A group of 30 cyclic imides (1-10a-c) was designed for evaluation as a selective COX-2 inhibitor and investigated in vivo for anti-inflammatory and analgesic activities. Compounds 6a, 6b, 7a and 7b exhibit optimal COX-2 inhibitory potency (IC50 = 0.18, 0.24, 0.28 and 0.36 μM; respectively) and selectivity index (SI) range of 363-668. In vitro COX-1/COX-2 inhibition structure-activity studies identified compound 6a as a highly potent (IC50 = 0.18 μM), and an extremely selective [COX-2 (SI) = 668] comparable to celecoxib [COX-2 (SI) > 384], COX-2 inhibitor that showed superior anti-inflammatory activity (ED50 = 54.0 mg/kg) relative to diclofenac (ED50 = 114 mg/kg). Molecular Docking study of the synthesized compound 6a into the active site of COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor. Docking study showed that the methoxy moeities of 6a inserted deep inside the 2°-pocket of the COX-2 active site, where the O-atoms of such groups underwent an H-bonding interaction with His(90) (3.02 Å), Arg(513) (1.94, 2.83 Å), and Gln(192) (3.25 Å).