RESUMO
Photocatalysis offers tremendous opportunities for enzymes to access new functions. Herein, we described a redox-neutral photocatalysis/enzymatic catalysis system for the asymmetric synthesis of chiral 1,2-amino alcohols via decarboxylative radical C-C coupling of N-arylglycines and aldehydes by combining an organic photocatalyst, eosin Y, and carbonyl reductase RasADH. Notably, this protocol avoids using any sacrificial reductants. A possible reaction mechanism proposed is that the transformation proceeds through sequential photoinduced decarboxylative radical addition to an aldehyde and a photoenzymatic deracemization pathway. This redox-neutral photoredox/enzymatic strategy is promising not only for effective synthesis of a series of chiral amino alcohols in a green and sustainable manner but also for the design of other novel C-C radical coupling transformations for the synthesis of bioactive molecules.
RESUMO
Designing new synthetic strategies for indazoles is a prominent topic in contemporary research. The transition-metal-catalyzed C-H activation/annulation sequence has arisen as a favorable tool to construct functionalized indazole derivatives with improved tolerance in medicinal applications, functional flexibility, and structural complexity. In the current review article, we aim to outline and summarize the most common synthetic protocols to use in the synthesis of target indazoles via a transition-metal-catalyzed C-H activation/annulation sequence for the one-step synthesis of functionalized indazole derivatives. We categorized the text according to the metal salts used in the reactions. Some metal salts were used as catalysts, and others may have been used as oxidants and/or for the activation of precatalysts. The roles of some metal salts in the corresponding reaction mechanisms have not been identified. It can be expected that the current synopsis will provide accessible practical guidance to colleagues interested in the subject.
Assuntos
Indazóis , Elementos de Transição , Catálise , Indazóis/química , Metais/química , Sais , Elementos de Transição/químicaRESUMO
A rapid and efficient protocol to fused pentacyclic compounds, the chromeno[3',4':3,4]pyrido[2,1-a]isoquinolines, via a diastereoselective 1,4-dipolar cycloaddition reaction of isoquinoline, dialkyl acetylenedicarboxylates, and 3-acetyl coumarins, is described.
Assuntos
Isoquinolinas/síntese química , Ácidos Carboxílicos/química , Cumarínicos/química , Reação de Cicloadição , Isoquinolinas/químicaRESUMO
Reported herein is an unprecedented and sequential three-component synthetic strategy for the preparation of polycyclic N-heterocyclic compounds. This synthetic protocol enabled the preparation of a series of novel nitrogen-containing pentacyclic compound under convenient conditions in excellent yields and short reaction time. The synthesized products were characterized by IR, 1H NMR, 13C NMR and mass spectra. Furthermore, the definitive structure of target compounds was confirmed by X-ray analysis.
Assuntos
Compostos HeterocíclicosRESUMO
One-pot, three-component reactions of structurally diverse salicylaldehydes with malononitrile (or ethylcyanoacetate) and diethyl (or dimethyl) phosphate are carried out in the presence of nano-rods ZnO as an efficient catalyst for the synthesis of biologically interesting 2-amino-4H-chromen-4-yl phosphonate derivatives. The value of this method lies in its mild and environmentally benign reaction, simple procedure, good yields, and ease of handling.