Intramolecular Carbonylative C-H Functionalization of 1,2,3- Triazoles for the Synthesis of Triazolo[1,5-a]indolones

Palladium-Catalyzed Carbonylative Synthesis of Aryl Selenoesters Using Formic Acid as an Ex Situ CO Source

A new catalytic protocol for the synthesis of selenoesters from aryl iodides and diaryl diselenides has been developed, where formic acid was employed as an efficient, low-cost, and safe substitute for toxic and gaseous CO. This protocol presents a high functional group tolerance, providing access to a large family of selenoesters in high yields (up to 97%) while operating under mild reaction conditions, and avoids the use of selenol which is difficult to manipulate, easily oxidizes, and has a bad odor. Additionally, this method can be efficiently extended to the synthesis of thioesters with moderate-to-excellent yields, by employing for the first time diorganyl disulfides as precursors.

Synthesis of Azidoanilines by the Buchwald-Hartwig Amination

We report a Buchwald-Hartwig amination compatible with azido functionality. Treatment of azidoaryl iodides and amines with fourth-generation Buchwald precatalyst coordinated by CPhos and sodium tert-butoxide in 1,4-dioxane at 50 °C afforded the corresponding azidoanilines while leaving the azido groups intact. The method showed a broad substrate scope and was applicable to the synthesis of diazido compounds as photoaffinity probe candidates of pharmaceutical amines and multiazido platform molecules.

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

Diverse strategies for the efficient and attractive synthesis of a wide variety of relevant 1,4,5-trisubstituted 1,2,3-triazole molecules are reported. The synthesis of this category of diverse fully functionalized 1,2,3-triazoles has become a necessary and unique research subject in modern synthetic organic key transformations in academia, pharmacy, and industry. The current review aims to cover a wide literature survey of numerous synthetic strategies. Recent reports (2017–2021) in the field of 1,4,5-trisubstituted 1,2,3-triazoles are emphasized in this current review.

Bimetallic Cu/Pd-catalyzed three-component azide-alkyne cycloaddition/isocyanide insertion: synthesis of fully decorated tricyclic triazoles

The construction of fully decorated 1,2,3-triazole-fused 5-, 6- and 7-membered rings has been disclosed via a bimetallic relay-catalyzed cascade process combining azide-alkyne cycloaddition, C(sp2)-H functionalization of intermediary 1,2,3-triazoles and isocyanide insertion. The salient features of this methodology include simple starting materials, reduced synthetic steps, good substrate scope and high efficiency.

Transition-Metal-Free Acceptorless Decarbonylation of Formic Acid Enabled by a Liquid Chemical-Looping Strategy

The selective decarbonylation of formic acid was achieved under transition-metal-free conditions. Using a liquid chemical-looping strategy, the thermodynamically favored dehydrogenation of formic acid was shut down, yielding a pure stream of CO with no H₂ or CO₂ contamination. The transformation involves a two-step sequence where methanol is used as a recyclable looping agent to yield methylformate, which is subsequently decomposed to carbon monoxide using alkoxides as catalysts.

Synthesis of Fused Bicyclic [1,2,3]-Triazoles from γ-Amino Diazoketones

Triazoles are an important class of N-heterocycles that are well known for their broad biological activities. In this work, we would like to demonstrate a direct synthesis of the rare fused bicyclic [1,2,3]-triazoles, employing γ-N-protected amino diazoketones as useful synthetic platforms. The strategy was based on the deprotection of a trifluoroacetamide group for the intramolecular and in situ generation of an α-diazo imine intermediate, followed by a 5-endo-dig cyclization to construct the bicyclic unit. In this fashion, the synthesis of a series of fused bicyclic [1,2,3]-triazoles could be carried out in good to excellent yields (63-95%).

C-H functionalization reactions under flow conditions

C-H functionalization technologies have progressed enormously in the last decade as testified by the great number of publications that have appeared in the literature, which are receiving great attention from researchers from different areas of expertise. While most of the protocols reported realize the C-H functionalization processes under batch conditions, there is a growing interest in the development of continuous-flow procedures aiming at increasing the performances of established methodologies or the definition of otherwise unfeasible transformations. This review summarizes the application of flow technologies for the realization of C-H functionalization reactions. According to the type of flow reactors necessary, two main general approaches are possible for the application of flow techniques, namely the use of homogeneous or heterogeneous conditions. Each example is discussed and accompanied by the description of the main features and benefits of the use of flow compared to batch conditions.

Ex Situ Generation of Sulfuryl Fluoride for the Synthesis of Aryl Fluorosulfates

A convenient transformation of phenols into the corresponding aryl fluorosulfates is presented: the first protocol to completely circumvent direct handling of gaseous sulfuryl fluoride (SO₂F₂). The proposed method employs 1,1'-sulfonyldiimidazole as a precursor to generate near-stoichiometric amounts of SO₂F₂ gas using a two-chamber reactor. With NMR studies, it was shown that this ex situ gas evolution is extremely rapid, and a variety of phenols and hydroxylated heteroarenes were fluorosulfated in good to excellent yields.