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The oxalamide skeleton is a common structural motif in many biologically active molecules. These scaffolds can be synthesized via ruthenium pincer complex-catalyzed acceptorless dehydrogenative coupling of ethylene glycol and amines. In this study, we elucidate the mechanism of this oxalamide synthesis using density functional theory calculations. The rate-determining state is identified as the formation of molecular hydrogen following the oxidation of hydroxyacetamide to oxoacetamide. In predictive catalysis exercises, various modifications to the ruthenium pincer catalyst were investigated to assess their impact on the reactivity. [ABSTRACT FROM AUTHOR]

In this study we present a method for functionalizing C60 through a Rh‐catalyzed cyclization reaction with 1,6‐enynes, resulting in the formation of a fused bicyclic structure. Additionally, fullerene derivatives are further functionalized through regioselective photooxygenation reactions. Our DFT calculations reveal two distinct reaction pathways: one involving rhodium‐catalyzed cycloisomerization of the enyne followed by Diels‐Alder with C60, and the other featuring a rhodium‐catalyzed [2+2+2] cycloaddition of enyne and C60 followed by isomerization. Surprisingly, both pathways exhibit nearly identical energy barriers. However, experimental tests indicate that the predominant pathway varies depending on the substitution motifs of the substrates. [ABSTRACT FROM AUTHOR]

The trapping of the elusive vinylogous position of a vinyl carbene with an aliphatic C(sp3)−H bond has been achieved for the first time during a silver‐catalyzed carbene/alkyne metathesis (CAM) process. A Tpx‐containing silver complex first promotes the generation of a donor‐acceptor silver carbene which triggers CAM, generating a subsequent donor‐donor vinyl silver carbene species, which then undergoes a selective vinylogous C(sp3)−H bond insertion, leading to the synthesis of a new family of benzoazepines. Density functional theory (DFT) calculations unveil the reaction mechanism, which allows proposing that the C−H bond insertion reaction takes place in a stepwise manner, with the hydrogen shift being the rate determining step. [ABSTRACT FROM AUTHOR]

A study shows that arenediazonium salts are attractive partners in palladium-catalyzed cross-coupling reactions. The use of arenediazonium salts in palladium-catalyzed reactions has made it possible to synthesize cross-coupled compounds that were not available by using classical halides or oxygen-based electrophiles.

Nitrogen containing 15-membered triacetylenic macrocycles known as 1,6,11-tris(arylsulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-triynes and enediynic macrocycles called 1,6,11-tris(arylsulfonyl)-1,6,11-triazacyclopentadeca-3-ene-8,13-diynes were prepared to test [2+2+2] cycloisomerization processes catalyzed by transition metals. The RhCl(CO)(PPh3)2 complex was found to catalyze the cycloisomerization reaction giving the desired cycloadducts in high yields.

A series of synthetic chemistry experiments suitable for advanced undergraduate chemistry students learning about catalytic and stoichiometric reaction methodologies is described. Preparation of aniline derivatives with HOOH as the oxidant and FeCl(sub.2)py(sub.4)(super.+) as catalyst is covered. The students are to think about design of cost-effective and environmentally sound synthetic routes and about sustainable global growth. Students can learn about the differences between the catalytic reactions and the stoichiometric reactions.

The cascade cyclization reactions of 1,5‐bisallenes grant access to a great variety of products by precisely tuning the catalyst system and/or the reagents involved. Herein, we present our findings that 1,5‐bisallenes react with two molecules of dimethyl acetylenedicarboxylate to afford, in a completely diastereoselective manner, cis‐3,4‐arylvinyl pyrrolidines and cyclopentanes. DFT calculations have been used to postulate a mechanism for the developed reaction which encompasses a [2+2+2] cycloaddition reaction of the two alkynes and the external double bond of one allene, followed by a cycloisomerization involving the internal double bond of the second allene. [ABSTRACT FROM AUTHOR]

The development of catalytic methodologies involving the formation of C–C bonds to enable the generation of cyclic systems constitutes a field of great relevance in synthetic organic chemistry. One paradigmatic process to accomplish this goal efficiently is the transition-metal-catalyzed [2 + 2 + 2] cycloaddition reaction, since it permits the formation of a wide range of highly functionalized 6-membered carbo- and heterocyclic molecules in a single step with high efficiency and perfect atom economy. A key feature of these transformations is the mechanistic pathway that they follow, since a deep knowledge of this mechanism may enable us to understand and improve the efficiency of the reaction. This review covers the mechanistic aspects, studied both from theoretical and experimental points of view, of the transition-metal-catalyzed [2 + 2 + 2] cycloaddition reaction involving all kinds of unsaturated substrates with metals such as Co, Ni, Ru, Rh, Ir, Pd, Zr, Ti, Ta, and Nb. A thorough overview is undertaken, from the seminal studies until the present day, of the key mechanistic aspects that influence the reactivity and selectivity of the reaction, comparing the involvement of different unsaturated substrates as well as the different transition metals used. [ABSTRACT FROM AUTHOR]