Green Conversion of CO2 and Propargylamines Triggered by Triply Synergistic Catalytic Effects in Metal-Organic Frameworks

Cyclization of propargylamines with CO₂ to obtain 2-oxazolidone heterocyclic compounds is an essential reaction in industry but it is usually catalyzed by noble-metal catalysts with organic bases as co-catalysts under harsh conditions. We have synthesized a unique Cu^I /Cu^II mixed valence copper-based framework {[(Cu^I ₆ I₅ )Cu₃ ^II L₆ (DMA)₃ ](NO₃ )⋅9DMA}_n (1) with good solvent and thermal stability, as well as a high density of uncoordinated amino groups evenly distributed in the large nanoscopic channels. Catalytic experiments show that 1 can effectively catalyze the reaction of propargylamines with CO₂ , and the yield can reach 99 %. The turnover frequency (TOF) reaches a record value of 230 h^-1 , which is much higher than that of reported noble-metal catalysts. Importantly, this is the first report of heterogeneously catalyzed green conversion of propargylamines with CO₂ without solvents and co-catalysts under low temperature and atmospheric pressure. A mechanistic study reveals that a triply synergistic catalytic effect between Cu^I /Cu^II and uncoordinated amino groups promotes highly efficient and green conversion of CO₂ . Furthermore, 1 directly catalyzes this reaction with high efficiency when using simulated flue gas as a CO₂ source.

Construction of piperidine-2,4-dione-type azaheterocycles and their application in modern drug development and natural product synthesis

The review surveys the existing routes to piperidine-2,4-dione-type heterocycles including derivatives with the most vital types of biological activity. This heterocyclic platform is ideal for the construction of modern drugs and natural products.

Catalytic formation of N3-substituted quinazoline-2,4(1H,3H)-diones by Pd(ii)EN@GO composite and its mechanistic investigations through DFT calculations

Modified GO based palladium composite was synthesized for catalytic synthesis of N3-substituted ouinazoline-2,4(1H,3H)-diones and the mechanistic route was theoretically investigated.

I2-Promoted Multicomponent Dicyclization and Ring-Opening Sequences: Direct Synthesis of Benzo[e][1,4]diazepin-3-ones via Dual C-O Bond Cleavage

A novel and efficient formal [4 + 2+1] annulation of aryl methyl ketones and 2-aminobenzyl alcohols for the synthesis of benzo[e][1,4]diazepin-3-ones is reported. This reaction successfully affords diverse seven-membered ring lactams via dual C-O bond cleavage. A preliminary mechanistic study showed that a multicomponent dicyclization and ring-opening sequence might occur, with the introduction of methyl sulfide proposed as the last step. This efficient strategy with mild reaction conditions and a broad substrate scope has potential applications in chemistry and medicine.

Recent advances in nucleophile-triggered CO2-incorporated cyclization leading to heterocycles

CO₂, as a sustainable, feasible, abundant one-carbon synthon, has been utilized in carboxylative cyclization, carbonylative cyclization, and reductive cyclization.

The dearomative annulation between N-2-pyridylamidine and CO2 toward pyrido[1,2-a]-1,3,5-triazin-4-ones

A base-promoted dearomative annulation between N-2-pyridylamidine and an atmospheric pressure of CO₂ was developed, affording a series of pyrido[1,2-a]-1,3,5-triazin-4-ones in moderate to excellent yields.

DBU-promoted carboxylative cyclization of o-hydroxy- and o-acetamidoacetophenone

The carboxylative cyclization of o-hydroxy- and o-acetamidoacetophenone with carbon dioxide promoted by the organic base 1,8-diazabicycloundec-7-ene (DBU) is reported. This reaction provides convenient access to the biologically important compounds 4-hydroxy-2H-chromen-2-one and 4-hydroxy-2(1H)-quinolinone in moderate to good yields using carbon dioxide as the carboxylation reagent. An acyl migration from nitrogen to carbon is observed in the reaction of o-acetamidoacetophenone.

Synthesis of oxazolidine-2,4-diones by a tandem phosphorus-mediated carboxylative condensation–cyclization reaction using atmospheric carbon dioxide

A novel access to oxazolidine-2,4-diones using atmospheric CO₂ and readily available substrates under mild and transition-metal-free conditions is developed.