Titanium catalysis for the synthesis of fine chemicals – development and trends

Chemical Society Reviews, Год журнала: 2020, Номер 49(19), С. 6947 - 6994

Опубликована: Янв. 1, 2020

Atlas as a Titan(ium) is holding the earth-abundant chemistry world. Titanium second most abundant transition metal, key player in important industrial processes (e.g. polyethylene) and shows much promise for diverse applications future.

Язык: Английский

---

Carbodiimide-based synthesis of N-heterocycles: moving from two classical reactive sites to chemical bond breaking/forming reaction

Chemical Society Reviews, Год журнала: 2020, Номер 49(16), С. 5810 - 5849

Опубликована: Янв. 1, 2020

Carbodiimides are a unique class of heterocumulene compounds that display distinctive chemical properties. The rich chemistry carbodiimides has drawn increasing attention from chemists in recent years and made them exceedingly useful modern organic chemistry, especially the synthesis N-heterocycles. This review outlined extensive application N-heterocycles 1980s to today. A wide range reactions for various types N-heterocyclic systems (three-, four-, five-, six-, seven-, larger-membered fused heterocycles) have been developed on basis their derivatives.

Язык: Английский

---

Transition metal-catalysed carbene- and nitrene transfer to carbon monoxide and isocyanides

Chemical Society Reviews, Год журнала: 2022, Номер 51(14), С. 5842 - 5877

Опубликована: Янв. 1, 2022

Transition metal-catalysed carbene- and nitrene transfer to the C1-building blocks carbon monoxide isocyanides provides heteroallenes (i.e. ketenes, isocyanates, ketenimines carbodiimides). These are versatile reactive compounds allowing in situ transformation towards numerous functional groups organic compounds, including heterocycles. Both one-pot tandem processes have been developed providing valuable synthetic methods for chemistry toolbox. This review discusses all known transition reactions of hereby obtained, with a special focus on general mechanistic considerations.

Язык: Английский

---

Silver-Catalyzed Cascade Cyclization Reaction of Isocyanides with Sulfoxonium Ylides: Synthesis of 3-Aminofurans and 4-Aminoquinolines

Organic Letters, Год журнала: 2020, Номер 22(19), С. 7640 - 7644

Опубликована: Сен. 15, 2020

A silver-catalyzed cascade cyclization reaction of isocyanides with sulfoxonium ylides has been developed for the first time. This provides a new and efficient method construction highly functionalized 3-aminofurans 4-aminoquinolines from readily available starting materials in single step.

Язык: Английский

---

Update for Reactions of Group 4 Metallocene Bis(trimethylsilyl)acetylene Complexes: A Never-Ending Story?

Organometallics, Год журнала: 2020, Номер 39(24), С. 4403 - 4414

Опубликована: Ноя. 18, 2020

Recently reported reactions of group 4 metallocene bis(trimethylsilyl)acetylene complexes from the last two years are summarized. This could be considered as a never-ending story. A recently alternative and very straightforward method for preparation well-known alkyne complex Cp2Ti(η2-Me3SiC2SiMe3) by Beckhaus et al. in future have great effect on application this complex. Similar improvements made earlier Tilley co-workers Zr analogue Cp2Zr(py)(Me3SiC2SiMe3) enabled preparative organometallic organic chemists to establish reagent wide range coupling reactions. Examples summarized review. These similar reagents represent excellent sources yield reactive coordinatively electronically unsaturated fragments [Cp′2M]. They will potential large number interesting applications future.

Язык: Английский

---

Ti-Catalyzed and -Mediated Oxidative Amination Reactions

Accounts of Chemical Research, Год журнала: 2021, Номер 54(17), С. 3476 - 3490

Опубликована: Авг. 23, 2021

ConspectusTitanium is an attractive metal for catalytic reaction development: it earth-abundant, inexpensive, and generally nontoxic. However—like most early transition metals—catalytic redox reactions with Ti are difficult because of the stability high-valent TiIV state. Understanding fundamental mechanisms behind processes key making progress toward potential applications. This Account details recent in Ti-catalyzed (and -mediated) oxidative amination that proceed through formally TiII/TiIV cycles.This class built on our initial discovery [2 + 2 1] pyrrole synthesis from alkynes azobenzene, where detailed mechanistic studies have revealed important factors allow turnover despite inherent difficulty redox. Two conclusions (1) low-valent intermediates catalysis can be stabilized coordination π-acceptor substrates or products, they act as "redox-noninnocent" ligands metal-to-ligand π back-donation, (2) reductive elimination π-type electrocyclic (or pericyclic) rather than direct σ-bond coupling.The reactive species imidos (Ti≡NR), which generated either aryl diazenes (RN═NR) organic azides (RN3). These then undergo 2] cycloadditions alkynes, resulting coupled to array other unsaturated functional groups, including alkenes, nitriles, nitrosos. basic reactivity pattern has been extended into a broad range stoichiometric multicomponent coupling small molecules, leading syntheses various heterocycles aminated building blocks.For example, two different leads pyrroles, while nitriles pyrazoles. heterocycle often yield substitution patterns complementary those classical condensation routes provide access new electron-rich, highly substituted heteroaromatic scaffolds. Furthermore, alkyne carboamination accomplished via yielding α,β-unsaturated imine cyclopropylimine blocks. New methods such α-diimination, isocyanide imination, ring-opening strained alkenes continuously emerging result better understanding catalysis.Ultimately, these -mediated demonstrate importance examining often-overlooked elements like metals lens modern catalysis: lack utility, frequently undiscovered transformations orthogonal selectivity their late counterparts.

Язык: Английский

---

Synthesis of 4-Tetrazolyl-Substituted 3,4-Dihydroquinazoline Derivatives with Anticancer Activity via a One-Pot Sequential Ugi-Azide/Palladium-Catalyzed Azide-Isocyanide Cross-Coupling/Cyclization Reaction

The Journal of Organic Chemistry, Год журнала: 2022, Номер 87(15), С. 9488 - 9496

Опубликована: Июль 26, 2022

A new one-pot preparation of 4-tetrazolyl-3,4-dihydroquinazolines has been reported. The Ugi-azide reactions 2-azidobenzaldehydes, amines, trimethylsilyl azide, and isocyanides produced azide intermediates without separation, which were treated with to give 4-tetrazolyl-3,4-dihydroquinazoline derivatives through a sequential Palladium-catalyzed azide-isocyanide cross-coupling/cyclization reaction in moderate good yields. biological evaluation demonstrated that compound 6c inhibited breast cancer cells well displayed broad applications for synthesis medicinal chemistry.

Язык: Английский

---

Cp₂Ti(κ²-^tBuNCN^tBu): A Complex with an Unusual κ² Coordination Mode of a Heterocumulene Featuring a Free Carbene

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(17), С. 8006 - 8018

Опубликована: Апрель 2, 2020

Although there are myriad binding modes of heterocumulenes to metal centers, the monometallic κ

Язык: Английский

---

Atomically Defined Nano-Propeller Fe₃Co₆Se₈(Ph₂PNTol)₆: Functional Model for the Electronic Metal-Support Interaction Effect, and High Catalytic Activity for Carbodiimide Formation

Journal of the American Chemical Society, Год журнала: 2019, Номер unknown

Опубликована: Ноя. 26, 2019

Atomically defined interfaces that maximize the density of active sites and harness electronic metal–support interaction are desirable to facilitate challenging multielectron transformations, but their synthesis remains a considerable challenge. We report rational atomically metal chalcogenide nanopropeller Fe3Co6Se8L6 (L = Ph2PNTol) featuring three Fe edge sites, its ensuing catalytic activity for carbodiimide formation. The complex between edges Co6Se8 support, including interplay oxidation state, substrate coordination, interaction, is probed in detail using chemical electrochemical methods, extensive single crystal X-ray diffraction, absorption Mössbauer spectroscopy.

Язык: Английский

---

Elevating 1-tert-Butyl-3-ethylcarbodiimide (TBEC) as a Reagent for Sustainable Peptide Synthesis: Quality Assessment and Minimizing Racemization, Precipitation, and Radical-Induced Side Reactions by TBEC/Oxyma Couplings in an Environmentally Sensible Solvent

Organic Process Research & Development, Год журнала: 2023, Номер 27(7), С. 1348 - 1364

Опубликована: Июнь 23, 2023

The finding that the widely used peptide coupling reagents DIC and Oxyma form toxic H-CN (McFarland, A. D. Org. Process Res. Dev. 2019, 23, 2099) has prompted studies aimed at minimization, attained, for example, by solvent engineering (Erny, M. 2020, 24, 1341) substituting with TBEC (Manne, S. R. 2022, 26, 2894). Here, an integrated study of TBEC/Oxyma as couplers is reported, focusing not only on performance in couplings but also its cost, hazards associated use, sustainability route synthesis, end life strategies, well potential impact impurities reagent synthesis. TBEC/Oxyma-mediated NBP/EtOAc (1:4) proceeded minimal racemization, free precipitation, radical side reactions irrespective quality. These results hold great promise broad adoption suitable green media a strategy sustainable synthesis from R&D lab to manufacturing plant.

Язык: Английский

---