Explore the vast range of titles available.

A two-step, one-pot synthesis of 3-substituted 1H-dibenzo[e,g]indazoles in good to high yields via a LiOtBu-promoted intramolecular 1,3-dipolar cyclization of 2′-alkynyl-biaryl-2-aldehyde N-tosylhydrazones was developed. The N-Ts-hydrazones used were prepared in situ via the reactions of 2′-alkynyl-biaryl-2-aldehydes and TsNHNH[sub.2](p-methylbenzenesulfonohydrazide). Two types of signals related to the hydrogen bonds, forming in several products, were observed in the [sup.1]H NMR spectra recorded in DMSO-d[sub.6], assigned to N-H bonds in their dimeric species of product and tautomer.

The reactivity of cyclic α-diazo monocarbonyl compounds differs from that of their acyclic counterparts. In this review, we summarize the current literature available on the synthesis and synthetic applications of three major classes of cyclic α-diazo monocarbonyl compounds: α-diazo ketones, α-diazo lactones and α-diazo lactams.

An in‐depth mechanistic study for the photogeneration of free diazoalkanes from N‐tosylhydrazone precursors by combining observations from synthesis with spectroscopic and theoretical methods is presented. The N‐tosylhydrazones have been previously established as donors for alkyl diazo species upon light irradiation, but exact mechanistic details of this photodissociation have remained elusive. Investigations of cyclohexane tosylhydrazone (CyNNTsH) by time‐resolved FTIR spectroscopy proved the role of the deprotonated CyNNTs− as the light‐harvesting species and revealed an intricate dependency of the thermal lifetime of the resulting diazoalkane on the deprotonating base. Computational studies including multiple approaches and levels of theory as well as rigorous benchmarking elucidated the dissociation mechanism via an allowed charge transfer state, a resulting destabilization of the dissociating bond, and a fast change of electronic character of the S1. These insights allow to suggest specific reaction conditions for photolabile or previously incompatible reaction partners thus paving way towards photo‐orthogonal synthetic strategies. A combined computational and experimental study elucidates the mechanism of the light‐induced formation of free diazoalkanes in detail. Starting from deprotonated tosylhydrazone as the light‐harvesting species, it undergoes bond dissociation from a charge transfer state. Based on our findings, including strong solvent and counterion effects, we can suggest suitable reaction conditions for photo‐orthogonal synthesis applications.

An efficient multicomponent reaction of newly designed β-trifluoromethyl β-diazo esters, acetonitrile, and carboxylic acids via an interrupted esterification process under copper-catalyzed conditions has been developed, which affords various unsymmetrical β-trifluoromethyl N , N -diacyl-β-amino esters in good to excellent yields. The reaction features mild conditions, a wide scope of β-amino esters and carboxylic acids, and also applicability to large-scale synthesis, thus providing an efficient way for the synthesis of β-trifluoromethyl β-diacylamino esters. Furthermore, this reaction represents the first example of a Mumm rearrangement of β-trifluoromethyl β-diazo esters.

Click chemistry is a concept in which modular synthesis is used to rapidly find new molecules with desirable properties 1 . Copper( i )-catalysed azide–alkyne cycloaddition (CuAAC) triazole annulation and sulfur( vi ) fluoride exchange (SuFEx) catalysis are widely regarded as click reactions 2 – 4 , providing rapid access to their products in yields approaching 100% while being largely orthogonal to other reactions. However, in the case of CuAAC reactions, the availability of azide reagents is limited owing to their potential toxicity and the risk of explosion involved in their preparation. Here we report another reaction to add to the click reaction family: the formation of azides from primary amines, one of the most abundant functional groups 5 . The reaction uses just one equivalent of a simple diazotizing species, fluorosulfuryl azide 6 – 11 (FSO 2 N 3 ), and enables the preparation of over 1,200 azides on 96-well plates in a safe and practical manner. This reliable transformation is a powerful tool for the CuAAC triazole annulation, the most widely used click reaction at present. This method greatly expands the number of accessible azides and 1,2,3-triazoles and, given the ubiquity of the CuAAC reaction, it should find application in organic synthesis, medicinal chemistry, chemical biology and materials science. A ‘click’ reaction is developed for the simple and rapid formation of azides from primary amines, and is used to prepare a library of over 1,200 azides for subsequent use in the existing triazole annulation click reaction.

The nitrite ion (NO2−) is a vital inorganic species that occurs both in natural ecological systems and human bodies. The high concentration of NO2− can be harmful for animal and human health. It is important to develop a simple, sensitive, reliable, and economic methodology to precisely monitor NO2− in various environmental and biological fields. Thus, a novel nitrite biosensor based on carbon quantum dots (PA-CDs) has been constructed and prepared via a high-efficiency, one-pot hydrothermal route using primary arylamines (PA) such as m-phenylenediamine. The device exhibits bright green fluorescence and a high quantum yield of 20.1% in water. In addition, the PA-CDs also possess two broad linear ranges: 0.05–1.0 μM and 1.0–50 μM with a low detection limit of 7.1 nM. The classical diazo reaction is firstly integrated into the PA-CD system by primary arylamines, which endows the system with high sensitivity and specific selectivity towards nitrite. Importantly, the nanosensor can detect NO2− in environmental water and serum samples with high fluorescence recoveries, demonstrating its feasibility in practical applications. This work broadens a new method to fabricate novel nanosensors and provides a prospective application for fluorescent carbon quantum dots (CDs).

Transition-metal-catalyzed directed C–H functionalization with various carbene precursors has been widely employed for constructing a wide range of complex and diverse active molecules through metal carbene migratory insertion processes. Among various carbene precursors, iodonium ylides serve as a novel and emerging carbene precursor with features including easy accessibility, thermal stability and high activity, which have attracted great attention from organic chemists and have achieved tremendous success in organic transformation. In this review, recent progress on the application of iodonium ylides with multifunctional coupling characteristics in C–H bond activation reactions is summarized, and the potential of iodonium ylides is discussed.

The Cu(II)-catalysed [2,3]-sigmatropic rearrangement of allyl and propargyl sulfides with the fluorinated diazo compound, 2-diazo-1,1,3,3,3-pentafluoropropyl phosphonate, has been investigated experimentally and computationally. The corresponding products 2 and 3a–d were obtained in yields of up to 79 %. Kinetic studies and DFT calculations indicate that Cu(I), generated in situ by reduction of Cu(II) with the diazo substrate, is the catalytically active species. The reaction proceeds via formation of a copper carbene and sulfonium ylide, which undergoes a facile [2,3]-sigmatropic rearrangement. These results expand the synthetic utility of fluorinated diazo compounds and provide mechanistic insight into the Doyle-Kirmse reaction under copper catalysis.

A practically convenient and streamlined protocol for the trans -diastereoselective introduction of an aryl substituent at position 4 of the 1,4-dihydroisoquinol-3-one (1,4-DHIQ) scaffold is presented. The protocol involves direct Regitz diazo transfer onto readily available 3(2 H )-isoquinolones followed by TfOH-promoted hydroarylation by an arene molecule. Screening of the novel 1,2,4-trisubstituted 1,4-DHIQs against cancer cell lines confirmed high cytotoxicity of selected analogs, which validates this new chemotype for further investigations as anticancer cytotoxic agents.

Lung cancer cells are well-documented to rewire their metabolism and energy production networks to support rapid survival and proliferation. This metabolic reorganization has been recognized as a hallmark of cancer. The increased uptake of glucose and the increased activity of the glycolytic pathway have been extensively described. However, over the past years, increasing evidence has shown that lung cancer cells also require glutamine to fulfill their metabolic needs. As a nitrogen source, glutamine contributes directly (or indirectly upon conversion to glutamate) to many anabolic processes in cancer, such as the biosynthesis of amino acids, nucleobases, and hexosamines. It plays also an important role in the redox homeostasis, and last but not least, upon conversion to α-ketoglutarate, glutamine is an energy and anaplerotic carbon source that replenishes tricarboxylic acid cycle intermediates. The latter is generally indicated as glutaminolysis. In this review, we explore the role of glutamine metabolism in lung cancer. Because lung cancer is the leading cause of cancer death with limited curative treatment options, we focus on the potential therapeutic approaches targeting the glutamine metabolism in cancer.