A mineralogically-inspired silver–bismuth hybrid material: an efficient heterogeneous catalyst for the direct synthesis of nitriles from terminal alkynes

Mechanochemistry: New Tools to Navigate the Uncharted Territory of "Impossible" Reactions

Mechanochemical transformations have made chemists enter unknown territories, forcing a different chemistry perspective. While questioning or revisiting familiar concepts belonging to solution chemistry, mechanochemistry has broken new ground, especially in the panorama of organic synthesis. Not only does it foster new "thinking outside the box", but it also has opened new reaction paths, allowing to overcome the weaknesses of traditional chemistry exactly where the use of well-established solution-based methodologies rules out progress. In this Review, the reader is introduced to an intriguing research subject not yet fully explored and waiting for improved understanding. Indeed, the study is mainly focused on organic transformations that, although impossible in solution, become possible under mechanochemical processing conditions, simultaneously entailing innovation and expanding the chemical space.

Synthesis of Aryl Nitriles via Aerobic Oxidative Cleavage of Aryl C=C Bonds with (NH4)2CO3 as the Nitrogen Source

An aerobic oxidative method was developed for conversion of arylethenes to aromatic nitriles using (NH4)2CO3 as the nitrogen source and Cu(NO3)2 as the catalyst. The present method allowed a series of arylethenes to underwent oxidative cleavage of C=C bonds to give the targeted products in low to high yields. In addition, the present conditions are compatible with many groups such as alkyl, alkoxy, N,N-dimethylamino, chloro, bromo, iodo, ester, cyano group, and so on.

Copper-Loaded Layered Bismuth Subcarbonate-Efficient Multifunctional Heterogeneous Catalyst for Concerted C-S/C-N Heterocyclization

An efficient self-supported Cu(II)Bi(III) bimetallic catalyst with a layered structure was designed and developed. By careful characterization of the as-prepared material, the host structure was identified to exhibit a Sillen-type bismutite framework, with copper(II) ions being loaded as guests. The heterogeneous catalyst enabled C–N and C–S arylations under mild reaction conditions and with high chemoselectivities, thus furnishing valuable phenothiazines via heterocyclization with wide substrate tolerance. As corroborated by detailed catalytic studies, the cooperative, bifunctional catalyst, bearing Lewis acid sites along with copper(II) catalytic sites, facilitated an intriguing concerted C–N/C–S heterocyclization mechanism. The heterogeneous nature of the catalytic reactions was verified experimentally. Importantly, the catalyst was successfully recycled and reused multiple times, persevering its original structural order as well as its initial activity.

Pulsed Laser in Liquids Made Nanomaterials for Catalysis

Catalysis is essential to modern life and has a huge economic impact. The development of new catalysts critically depends on synthetic methods that enable the preparation of tailored nanomaterials. Pulsed laser in liquids synthesis can produce uniform, multicomponent, nonequilibrium nanomaterials with independently and precisely controlled properties, such as size, composition, morphology, defect density, and atomistic structure within the nanoparticle and at its surface. We cover the fundamentals, unique advantages, challenges, and experimental solutions of this powerful technique and review the state-of-the-art of laser-made electrocatalysts for water oxidation, oxygen reduction, hydrogen evolution, nitrogen reduction, carbon dioxide reduction, and organic oxidations, followed by laser-made nanomaterials for light-driven catalytic processes and heterogeneous catalysis of thermochemical processes. We also highlight laser-synthesized nanomaterials for which proposed catalytic applications exist. This review provides a practical guide to how the catalysis community can capitalize on pulsed laser in liquids synthesis to advance catalyst development, by leveraging the synergies of two fields of intensive research.

Bismuth Subnitrate-Catalyzed Markovnikov-Type Alkyne Hydrations under Batch and Continuous Flow Conditions

Bismuth subnitrate is reported herein as a simple and efficient catalyst for the atom-economical synthesis of methyl ketones via Markovnikov-type alkyne hydration. Besides an effective batch process under reasonably mild conditions, a chemically intensified continuous flow protocol was also developed in a packed-bed system. The applicability of the methodologies was demonstrated through hydration of a diverse set of terminal acetylenes. By simply switching the reaction medium from methanol to methanol-d₄, valuable trideuteromethyl ketones were also prepared. Due to the ready availability and nontoxicity of the heterogeneous catalyst, which eliminated the need for any special additives and/or harmful reagents, the presented processes display significant advances in terms of practicality and sustainability.

Exploiting a silver–bismuth hybrid material as heterogeneous noble metal catalyst for decarboxylations and decarboxylative deuterations of carboxylic acids under batch and continuous flow conditions

A silver-containing hybrid material is reported as a heterogeneous noble metal catalyst for protodecarboxylations and decarboxylative deuterations of carboxylic acids.

Silver-Catalyzed Activation of Terminal Alkynes for Synthesizing Nitrogen-Containing Molecules

Alkynes are one of the most abundant chemicals in organic chemistry, and therefore the development of catalytic reactions to transform alkynes into other useful functionalities is of great value. In recent decades, extraordinary advances have been made in this area with transition-metal catalysis, and silver-based reagents are ideal for the activation of alkynes. This high reactivity is probably due to the superior π-Lewis acidic, carbophilic behavior of silver(I), allowing it to selectively activate carbon-carbon triple bonds (C≡C) through the formation of a silver-π complex. Within this field, we have been interested in the activation and subsequent reactions of readily accessible terminal alkynes for the synthesis of nitrogen-containing compounds, which has generally received less attention than methods involving internal alkynes. This is possibly due to the lack of suitable reactive reaction partners that are compatible under transition metals. Therefore, a thorough understanding of the factors that influence homogeneous silver catalysis and the identification of the appropriate reaction partners can provide a powerful platform for designing more efficient silver-catalyzed reactions of terminal alkynes. In this context, we envisioned that using readily available, environmentally benign, and inexpensive trimethylsilyl azide (TMSN₃) or an isocyanide as the nitrogen-donor would be the key to develop novel reactions of terminal alkynes.This Account describes our efforts since 2013 toward the development of novel silver-catalyzed tandem reactions of terminal alkynes with either TMSN₃ or isocyanides for the assembly of various nitrogen-containing compounds. The first section of this Account discusses the initial developments in the silver-catalyzed hydroazidation of terminal alkynes with TMSN₃ and the subsequent advances made in our laboratory. We first describe the discovery and experimental and computational mechanistic investigations of silver-catalyzed hydroazidation reactions, which is the most efficient strategy reported to date for accessing vinyl azides. Mechanistic study of this hydroazidation reaction provides an alternative activation mode for terminal alkyne conversion in transition metal catalysis. We then present the chemistry of in situ generated vinyl azides, including one-pot tandem radical addition/cyclization or migration reactions of terminal alkynes to access a variety of nitrogen-containing molecules. Finally, we discuss the one-pot, multistep tandem hydroazidation and 1,2-azide migratory gem-difluorination of terminal alkynes for the synthesis of β-difluorinated alkyl azides. The second section describes the silver-catalyzed coupling reactions between terminal alkynes and isocyanides, which offer a straightforward method for accessing synthetically useful building blocks, such as pyrroles, allenamides, benzofuran, vinyl sulfones, indazolines, propiolonitriles, and pyrazoles. The high efficiency, mild conditions, low cost, broad substrate scope, high chemo- and regioselectivity, step economy, and ecofriendliness of the developed approaches make them attractive and practical. The progress in this area provides guiding principles for designing new reactions of terminal alkynes that can be extended to various nitrogen-containing molecules of interest to medicinal and materials chemists.

Cu9O2(VO4)4Cl2, the First Copper Oxychloride Vanadate: Mineralogically Inspired Synthesis and Magnetic Behavior

A new spin-¹/₂ frustrated antiferromagnet, Cu₉O₂(VO₄)₄Cl₂, was synthesized via chemical vapor transport method that emulates mineral formation in volcanic fumaroles. Cu₉O₂(VO₄)₄Cl₂ is the first copper oxychloride vanadate obtained in the ternary CuO-V₂O₅-CuCl₂ anhydrous system. Copper ions constitute a three-dimensional complex framework with a topological structure novel for synthetic compounds but similar to that in the fumarolic mineral yaroshevskite. All of the oxygen atoms except for the O7 site are strongly bonded in the VO₄ tetrahedra. The O7 site belongs to an additional oxygen atom (O_a) being tetrahedrally coordinated by four Cu atoms, thus forming the OCu₄ tetrahedra. The structural formula can be represented as Cu₃[Cu₆O₂](VO₄)₄Cl₂ highlighting oxocentered units in the structure. IR spectra reveal several absorption bands at 526, 578, and 601 cm^-1 interpreted as a characteristic feature of the OCu₄ tetrahedra. Cu₉O₂(VO₄)₄Cl₂ reveals ferrimagnetic behavior with the Curie temperature T_C = 24 K and the uncompensated moment of M_r ∼ 1.9 μ_B/f.u.

Catalytic use of layered materials for fine chemical syntheses

The present work reviews the catalytic use of layered solid materials for fine chemical syntheses with focus on layered double hydroxides, but including other classes of layered compounds of catalytic relevance.

Functional layered materials with heavy metal lone pair cations, Pb2+, Bi3+, and Te4+

Syntheses, structures, representative properties, and the structure–property relationships for a series of functional layered materials are presented.