Recent Advances in N-O Bond Cleavage of Oximes and Hydroxylamines to Construct N-Heterocycle

Oximes and hydroxylamines are a very important class of skeletons that not only widely exist in natural products and drug molecules, but also a class of synthon, which have been widely used in industrial production. Due to weak N-O σ bonds of oximes and hydroxylamines, they can be easily transformed into other functional groups by N-O bond cleavage. Therefore, the synthesis of N-heterocycle by using oximes and hydroxylamines as nitrogen sources has attracted wide attention. Recent advances for the synthesis of N-heterocycle through transition-metal-catalyzed and radical-mediated cyclization classified by the type of nitrogen sources and rings are summarized. In this paper, the recent advances in the N-O bond cleavage of oximes and hydroxylamines are reviewed. We hope that this review provides a new perspective on this field, and also provides a reference to develop environmentally friendly and sustainable methods

[4 + 2] Annulation Cascades of 2‑Bromo-1-arylpropan-1-ones with Terminal Alkynes Involving C–Br/C–H Functionalization

Straightforward access to various substituted naphthalenones by copper-catalyzed [4 + 2] annulation cascades of 2-bromo-1-arylpropan-1-ones with terminal alkynes is presented. Employing a Cu­(MeCN)₄PF₄ catalyst and 1,10-phenanthroline (1,10-Phen) ligand enables the formation of three new C–C bonds in a single reaction via [4 + 2] annulation of a 2-bromo-1-arylpropan-1-one with an alkyne followed by α-alkylation with the other 2-bromo-1-arylpropan-1-one with excellent functional group tolerance and step efficiency

Complex Annulations through Silver Carbenoid Intermediate: An Alternative Entry to Transformations of 1,2,3-Triazoles

An alternative entry to transformations of <i>N</i>-sulfonyl-4-(2-(ethynyl)­aryl)-1,2,3-triazoles with various generated in situ or external nucleophiles by means of silver catalysis for producing diverse functionalized isoquinolines is described. Mechanistically, the reaction is proposed to involve a key silver carbenoid intermediate, thus enabling the formation of multiple chemical bonds via ring opening, N₂ extrusion, silver carbenoid formation, nucleophilic addition, and complex annulations cascades

Complex Annulations through Silver Carbenoid Intermediate: An Alternative Entry to Transformations of 1,2,3-Triazoles

An alternative entry to transformations of <i>N</i>-sulfonyl-4-(2-(ethynyl)­aryl)-1,2,3-triazoles with various generated in situ or external nucleophiles by means of silver catalysis for producing diverse functionalized isoquinolines is described. Mechanistically, the reaction is proposed to involve a key silver carbenoid intermediate, thus enabling the formation of multiple chemical bonds via ring opening, N₂ extrusion, silver carbenoid formation, nucleophilic addition, and complex annulations cascades

Complex Annulations through Silver Carbenoid Intermediate: An Alternative Entry to Transformations of 1,2,3-Triazoles

An alternative entry to transformations of <i>N</i>-sulfonyl-4-(2-(ethynyl)­aryl)-1,2,3-triazoles with various generated in situ or external nucleophiles by means of silver catalysis for producing diverse functionalized isoquinolines is described. Mechanistically, the reaction is proposed to involve a key silver carbenoid intermediate, thus enabling the formation of multiple chemical bonds via ring opening, N₂ extrusion, silver carbenoid formation, nucleophilic addition, and complex annulations cascades

Copper-Catalyzed Radical [2 + 2 + 1] Annulation of Benzene-Linked 1,<i>n</i>‑Enynes with Azide: Fused Pyrroline Compounds

A novel selective copper-catalyzed radical [2 + 2 + 1] annulation of benzene-linked 1,<i>n</i>-enynes with azido-benziodoxolone to access fused pyrroline compounds, including 3<i>H</i>-pyrrolo­[3,4-<i>c</i>]­quinolin-4­(3<i>aH</i>)-ones, chromeno­[3,4-<i>c</i>]­pyrrol-4­(9<i>bH</i>)-one, and indeno­[1,2-<i>c</i>]­pyrroline, has been developed, which proceeds via the addition of the azide radical to the alkene, annualtion, and azidation cascade

Metal-Free Oxidative <i>Ipso</i>-Carboacylation of Alkynes: Synthesis of 3‑Acylspiro[4,5]trienones from <i>N</i>‑Arylpropiolamides and Aldehydes

A general and metal-free radical route to synthesis of 3-acylspiro­[4,5]­trienones is established that utilizes TBHP (<i>tert</i>-butyl hydrogenperoxide) as an oxidation and a reaction partner to trigger the oxidative <i>ipso</i>-carboacylation of <i>N</i>-arylpropiolamides with aldehydes. This method offers a new difunctionalization of alkynes through oxidative cross coupling of the aldehyde C­(sp²)–H bond with an <i>ipso</i>-aromatic carbon

Manganese-Catalyzed Intermolecular Oxidative Annulation of Alkynes with γ‑Vinyl Aldehydes: An Entry to Bridged Carbocyclic Systems

Manganese-catalyzed intermolecular oxidative annulation of alkynes with γ-vinyl aldehydes involving acylation and alkylation is described, thus providing a scenario for the divergent synthesis of bridged carbocyclic systems. By means of this manganese-catalyzed alkyne dicarbofunctionalization strategy, three chemical bonds, including two C–C bonds and one C–H bond, are formed via an aldehyde C­(sp²)–H oxidative functionalization/[4 + 2] annulation/protonation cascade

1,2-Alkylarylation of Styrenes with α‑Carbonyl Alkyl Bromides and Indoles Using Visible-Light Catalysis

A new intermolecular 1,2-alkylarylation of styrenes with α-carbonyl alkyl bromides and indoles using <i>fac</i>-[Ir­(ppy)₃] as the photoredox catalyst has been developed. The method allows the simultaneous formation of two new carbon–carbon bonds through three component reaction, and represents a new single-electron transfer (SET) strategy for the 1,2-alkylarylation of the styrenes with broad substrate scope and excellent functional group tolerance

Integrin-Linked Kinase (ILK) Regulates Urinary Stem Cells Differentiation into Smooth Muscle via NF-κB Signal Pathway

Objectives. Urinary stem cells (USCs) have the capacity for unlimited growth and are promising tools for the investigations of cell differentiation and urinary regeneration. However, the limited life span significantly restricts their usefulness. This study is aimed at exploring the effect of integrin-linked kinase (ILK) on the smooth muscle cells (SMCs) differentiation of the dog USCs and investigating its molecular mechanism. Methods. An immortalized USCs cell line with the molecular markers and biological functions was prepared. After successfully inducing the differentiation of USCs into SMCs, the expression level of the unique key factor and its mechanisms in this process was determined through real-time polymerase chain reaction, Western blot, or Immunofluorescence staining. Results. We found that high cell density promoted USCs differentiation SMCs, and ILK was necessary for USCs differentiation into SMCs. Knocking down ILK decreased the expression of SMCs specific-marker, while using a selective ILK agonist increased the expression of SMCs specific-marker. Furthermore, ILK regulated SMCs differentiation in part through the activation of NF-κB pathway in USCs. A NF-κB activity assay showed overexpression of ILK could significantly upregulate NF-κB p50 expression, and NF-κB p50 acts as downstream signal molecular of ILK. Conclusion. High cell density induces the differentiation of USCs into SMCs, and ILK is a key regulator of myogenesis. Furthermore, NF-κB signaling pathway might play a crucial role in this process