This critical review examines transition metal-catalyzed decarboxylative couplings that have emerged within recent years as a powerful strategy to form carbon–carbon or carbon–heteroatom bonds starting from carboxylic acids. In these reactions, C–C bonds to carboxylate groups are cleaved, and in their place, new carbon–carbon bonds are formed. Decarboxylative cross-couplings constitute advantageous alternatives to traditional cross-coupling or addition reactions involving preformed organometallic reagents. Decarboxylative reaction variants are also known for Heck reactions, direct arylation processes, and carbon–heteroatom bond forming reactions.

Decarboxylative coupling reactions: a modern strategy for C–C-bond formation

Fluorescent nanodiamond is a new nanomaterial that possesses several useful properties, including good biocompatibility1, excellent photostability1,2 and facile surface functionalizability2,3. Moreover, when excited by a laser, defect centres within the nanodiamond emit photons that are capable of penetrating tissue, making them well suited for biological imaging applications1,2,4. Here, we show that bright fluorescent nanodiamonds can be produced in large quantities by irradiating synthetic diamond nanocrystallites with helium ions. The fluorescence is sufficiently bright and stable to allow three-dimensional tracking of a single particle within the cell by means of either one- or two-photon-excited fluorescence microscopy. The excellent photophysical characteristics are maintained for particles as small as 25 nm, suggesting that fluorescent nanodiamond is an ideal probe for long-term tracking and imaging in vivo, with good temporal and spatial resolution.

Mass production and dynamic imaging of fluorescent nanodiamonds

C−C bond forming reactions incarnate the core of organic synthesis because of their fundamental applications to molecular diversity and complexity. In recent years, use of carboxylic acid as one of the coupling partners in place of conventional organometallic reagents has seen an upsurge due to its potency to generate similar organometallic intermediates after decarboxylation. This Review provides an overview on the most recent progress in the field of C−C bond formation involving decarboxylation as a key step. Different important developments, which are not included in earlier Reviews in this area, have been summarized with representative examples and discussions on their reaction mechanisms.

Decarboxylation as the Key Step in C−C Bond‐Forming Reactions

Silver, known and utilized since ancient times, is a coinage metal, which has been widely used for various organic transformations in the past few decades. Currently, the silver-catalyzed reaction is one of the frontier areas in organic chemistry, and the progress of research in this field is very rapid. Compared with other transition metals, silver has long been believed to have low catalytic efficiency, and most commonly, it is used as either a cocatalyst or a Lewis acid. Interestingly, the discovery of Ag-catalysis has been significantly improved in recent years. Especially, Ag(I) has been demonstrated as an important and versatile catalyst for a variety of organic transformations. However, so far, there has been no systematic review on Ag-catalyzed C–H/C–C bond functionalization. In this review, we will focus on the development of Ag-catalyzed C–H/C–C bond functionalization and the corresponding mechanism.

Ag-catalyzed C–H/C–C bond functionalization

Sulfinic acids and their salts have recently emerged as versatile coupling partners to efficiently access a wide variety of hetero- and carbocyclic compounds, under relatively mild conditions. Their growing importance is attributable to their dual capacity for acting as nucleophilic or electrophilic reagents. This report summarizes recent advances in the preparation and use of sulfinates in organic synthesis.

Sulfinate derivatives: dual and versatile partners in organic synthesis

A straightforward, regioselective, and step-economical ligand-free palladium-catalyzed decarboxylative functionalization of coumarin-3-carboxylic acids is devised. This protocol is compatible with a wide variety of electron-donating and -withdrawing substituents and allows for construction of various biologically important π-electron extended coumarins.

Palladium-catalyzed decarboxylative cross-coupling reactions: a route for regioselective functionalization of coumarins.

A novel regioselective α-arylation of coumarins with readily available arenesulfonyl chlorides via palladium-catalyzed direct C—H functionalization under mild reaction conditions is described.

Highly Regioselective α-Arylation of Coumarins via Palladium-Catalyzed C-H Activation/Desulfitative Coupling.

Silver-catalyzed facile decarboxylation of coumarin-3-carboxylic acids

Advances in the Surface Functionalization of Nanodiamonds for Biological Applications: A Review

Free radicals and oxidative stress play important roles in the deterioration of materials, and free radicals are important intermediates in many biological processes The ability to detect these reactive species is a key step on the road to their understanding and ultimate control This short review highlights recent progress in the development of reagents for the detection of free radicals and reactive oxygen species with broad application to materials science as well as biology

Mina Barzegar Amiri Olia

Papers

Palladium-catalyzed decarboxylative cross-coupling reactions: a route for regioselective functionalization of coumarins.

Highly Regioselective α-Arylation of Coumarins via Palladium-Catalyzed C-H Activation/Desulfitative Coupling.

Silver-catalyzed facile decarboxylation of coumarin-3-carboxylic acids

Advances in the Surface Functionalization of Nanodiamonds for Biological Applications: A Review

New reagents for detecting free radicals and oxidative stress