Isotope-labeling of the fibril binding compound FSB via a Pd-catalyzed double alkoxycarbonylation

Formate Salt as a Bifunctional Reagent for Hydroxylation and Carbonylation Reactions Under Photochemically Driven Nickel Catalysis

In this study, we disclose for the first time that formate salt can be used as a bifunctional reagent for the synthesis of phenol derivatives and as a CO source for carbonylative cross-coupling processes using the COware gas reactor under activation free conditions. Key to this success is the in-situ synthesis of aryl formate via an unprecedented nickel/organophotocatalyst system under blue LED irradiation. This developed system demonstrated high applicability to various aryl iodide substrates for synthesizing phenol derivatives. Moreover, the generated CO could be utilized in a range of carbonylative C-heteroatom and C-C processes. Notably, commercially available H13COONa salt can serve as a bifunctional reagent for both synthesizing phenols and generating 13CO.

A chemoselective hydroxycarbonylation and 13C-labeling of aryl diazonium salts using formic acid as the C-1 source

We report a one-pot synthesis of aryl carboxylic acids utilizing HCOOH as a CO surrogate with low Pd-catalyst loading. This operationally simple and scalable method does not require use of a high-pressure reactor, two-chamber reaction vessel, phosphine ligand, or base and proceeds in a relatively short amount of time at ambient temperature. Notably, halides, including iodo and bromo groups, and nitro groups remain intact under these mild reaction conditions. This methodology has been successfully applied to synthesizing 13C-labeled aryl carboxylic acids with satisfactory yields.

Conservation of the Amyloid Interactome Across Diverse Fibrillar Structures

Several human proteins cause disease by misfolding and aggregating into amyloid fibril deposits affecting the surrounding tissues. Multiple other proteins co-associate with the diseased deposits but little is known about how this association is influenced by the nature of the amyloid aggregate and the properties of the amyloid-forming protein. In this study, we investigated the co-aggregation of plasma and cerebrospinal proteins in the presence of pre-formed amyloid fibrils. We evaluated the fibril-associated proteome across multiple amyloid fibril types that differ in their amino acid sequences, ultrastructural morphologies, and recognition by amyloid-binding dyes. The fibril types included aggregates formed by Amyloid β, α-synuclein, and FAS4 that are associated with pathological disorders, and aggregates formed by the glucagon and C-36 peptides, currently not linked to any human disease. Our results highlighted a highly similar response to the amyloid fold within the body fluid of interest. Fibrils with diverse primary sequences and ultrastructural morphologies only differed slightly in the composition of the co-aggregated proteins but were clearly distinct from less fibrillar and amorphous aggregates. The type of body fluid greatly affected the resulting amyloid interactome, underlining the role of the in vivo environment. We conclude that protein fibrils lead to a specific response in protein co-aggregation and discuss the effects hereof in the context of amyloid deposition.

The Development and Application of Two-Chamber Reactors and Carbon Monoxide Precursors for Safe Carbonylation Reactions

Low molecular weight gases (e.g., carbon monoxide, hydrogen, and ethylene) represent vital building blocks for the construction of a wide array of organic molecules. Whereas experimental organic chemists routinely handle solid and liquid reagents, the same is not the case for gaseous reagents. Synthetic transformations employing such reagents are commonly conducted under pressure in autoclaves or under atmospheric pressure with a balloon setup, which necessitates either specialized equipment or potentially hazardous and nonrecommended installations. Other safety concerns associated with gaseous reagents may include their toxicity and flammability and, with certain gases, their inability to be detected by human senses. Despite these significant drawbacks, industrial processes apply gaseous building blocks regularly due to their low cost and ready availability but nevertheless under a strictly controlled manner. Carbon monoxide (CO) fits with all the parameters for being a gas of immense industrial importance but with severe handling restrictions due to its inherent toxicity and flammability. In academia, as well as research and development laboratories, CO is often avoided because of these safety issues, which is a limitation for the development of new carbonylation reactions. With our desire to address the handling of CO in a laboratory setting, we designed and developed a two-chamber reactor (COware) for the controlled delivery and utilization of stoichiometric amounts of CO for Pd-catalyzed carbonylation reactions. In addition to COware, two stable and solid CO-releasing molecules (COgen and SilaCOgen) were developed, both of which release CO upon activation by either Pd catalysis or fluoride addition, respectively. The unique combination of COware with either COgen or SilaCOgen provides a simple reactor setup enabling synthetic chemists to easily perform safe carbonylation chemistry without the need for directly handling the gaseous reagent. With this technology, an array of low-pressure carbonylations were developed applying only near stoichiometric amounts of carbon monoxide. Importantly, carbon isotope variants of the CO precursors, such as (13)COgen, Sila(13)COgen, or even (14)COgen, provide a simple means for performing isotope-labeling syntheses. Finally, the COware applicability has been extended to reactions with other gases, such as hydrogen, CO2, and ethylene including their deuterium and (13)C-isotopically labeled versions where relevant. The COware system has been repeatedly demonstrated to be a valuable reactor for carrying out a wide number of transition metal-catalyzed transformations, and we believe this technology will have a significant place in many organic research laboratories.

Palladium-catalyzed carbonylative transformation of aryl chlorides and aryl tosylates

The developments in the carbonylative transformations of aryl chlorides and aryl tosylates have been collected and discussed.

Recent advances in the transition metal catalyzed carbonylation of alkynes, arenes and aryl halides using CO surrogates

Transition metal catalyzed carbonylation reactions using carbon monoxide as the C-1 source have occupied an all important position in catalysis which is subsequently related to organic synthesis and industrial synthesis of molecules.

Silica supported palladium-phosphine as a reusable catalyst for alkoxycarbonylation and aminocarbonylation of aryl and heteroaryl iodides

Novel, simple, stable and reusable silica-supported palladium phosphine complexes were prepared and found to be highly efficient for the carbonylation of unprotected hydroxy, amino, iodoindole and iodopyrazole under optimized conditions.

Effective palladium-catalyzed hydroxycarbonylation of aryl halides with substoichiometric carbon monoxide

A protocol for the Pd-catalyzed hydroxycarbonylation of aryl iodides, bromides, and chlorides has been developed using only 1-5 mol % of CO, corresponding to a p(CO) as low as 0.1 bar. Potassium formate is the only stoichiometric reagent, acting as a mildly basic nucleophile and a reservoir of CO. The substoichiometric CO could be delivered to the reaction from an acyl-Pd(II) precatalyst, which provides both the CO and an active catalyst, and thereby obviates the need for handling a toxic gas.