Carbon dioxide is a nontoxic and abundant chemical and has been widely used as a C1 building block for the synthesis of highly important chemicals. This greenhouse gas also has the ability to trigg...

CO2-Promoted Reactions: An Emerging Concept for the Synthesis of Fine Chemicals and Pharmaceuticals

A copper-catalyzed procedure enabling dynamic carbon isotope exchange is described. Utilizing the universal precursor [14C]CO2, this protocol allows to insert, in one single step, the desired carbon tag into carboxylic acids with no need of structural modifications. Reducing synthetic costs and limiting the generation of radioactive waste, this procedure will facilitate the access to carboxylic acids containing drugs and accelerate early 14C-based ADME studies supporting drug development.

https://ESOC2019.abstracts.eu/e69f6cd3ab91e33456be41d06c4f6b5f.pdf

Dynamic carbon isotope exchange of pharmaceuticals with labeled co 2

Carbon dioxide (CO2) is the major carbonaceous component of many planetary atmospheres, which includes the Earth throughout its history. Carbon fixation chemistry—which reduces CO2 to organics, utilizing hydrogen as the stoichiometric reductant—usually requires high pressures and temperatures, and the yields of products of potential use to nascent biology are low. Here we demonstrate an efficient ultraviolet photoredox chemistry between CO2 and sulfite that generates organics and sulfate. The chemistry is initiated by electron photodetachment from sulfite to give sulfite radicals and hydrated electrons, which reduce CO2 to its radical anion. A network of reactions that generates citrate, malate, succinate and tartrate by irradiation of glycolate in the presence of sulfite was also revealed. The simplicity of this carboxysulfitic chemistry and the widespread occurrence and abundance of its feedstocks suggest that it could have readily taken place on the surfaces of rocky planets. The availability of the carboxylate products on early Earth could have driven the development of central carbon metabolism before the advent of biological CO2 fixation. Carbon dioxide is a substantial component of many planetary atmospheres, but reduction of carbon dioxide requires conditions and substrates that are rare on planetary surfaces. Now, the reduction of carbon dioxide to organic species with biological relevance has been photochemically coupled to the oxidation of sulfite, suggesting that prebiotic carbon fixation could take place on the surfaces of rocky planets.

/pdf/prebiotic-photoredox-synthesis-from-carbon-dioxide-and-5f55zjirrs.pdf

Prebiotic photoredox synthesis from carbon dioxide and sulfite.

In our ongoing efforts in preparing tool compounds for investigating and controlling the biosynthesis of phenazines, we recognized the limitations of existing protocols for C–N bond formation of electron-deficient anilines when using reductive amination. After extensive optimization, we have established three robust and scalable protocols for the reductive amination of ketones with electron-deficient anilines, by using either BH3·THF/AcOH/CH2Cl2 (method A), with reaction times of several hours, or the more powerful combinations BH3·THF/TMSCl/DMF (method B) and NaBH4/TMSCl/DMF (method C), which give full conversions for most substrates within 10 to 25 minutes. The scope and limitations of these reactions have been defined for 12 anilines and 14 ketones.

A General and Direct Reductive Amination of Aldehydes and Ketones with Electron-Deficient Anilines

A simple covalent organic framework (COF) bearing β-ketoenamine units as a potential heterogeneous ligand for ZnII-catalyzed fixation and transformation of CO2 into value-added chemicals is reported. Catalytic investigations convincingly demonstrated that the ZnII-functionalized covalent organic framework (Zn@TpTta) exhibits perfect catalytic activity in the fixation of CO2 for diverse epoxides with various substituents under sustainable conditions. A variety of terminal epoxides and slightly more complicated disubstituted epoxides were transformed into the corresponding cyclic carbonates with satisfactory to excellent yields (i.e., 69 to 99% yield) upon exposure to CO2 (1 atm) under solvent-free conditions (sustainable approach). On the other hand, this ZnII-loaded covalent organic framework also displayed excellent performance in facilitating atmospheric cyclizative CO2 capture, which led to the formation of diverse cyclic carbamates (i.e., 61 to 94% yield) from unsaturated amine systems using N-iodosuccinimide (NIS) as an iodinating agent and PEG-400 as a biodegradable and green polymeric solvent under base-free conditions (sustainable approach). The newly synthesized COF-based catalyst, namely, Zn@TpTta, has been completely characterized by SEM (scanning electron microscopy), EDX (energy dispersive X-ray analysis), HRTEM (high-resolution transmission electron microscopy), BET (Brunauer-Emmett-Teller), PXRD (powder X-ray diffraction), XPS (X-ray photoelectron spectroscopy), ICP (inductively coupled plasma), etc. More intriguingly, the catalytic system could be recycled over five times without a noticeable loss of catalytic performance for both reactions. This study opens an avenue for the Zn(II) embedded COF as a promising platform for regulating regioselectivity.

A Zn(II)-functionalized COF as a recyclable catalyst for the sustainable synthesis of cyclic carbonates and cyclic carbamates from atmospheric CO2.

Thermodynamic and kinetic control of a chemical process is the key to access desired products and states. Changes are made when a desired product is not accessible; one may manipulate the reaction with additional reagents, catalysts and/or protecting groups. Here we report the use of carbon dioxide to accelerate cyanohydrin synthesis under neutral conditions with an insoluble cyanide source (KCN) without generating toxic HCN. Under inert atmosphere, the reaction is essentially not operative due to the unfavored equilibrium. The utility of CO2 -mediated selective cyanohydrin synthesis was further showcased by broadening Kiliani-Fischer synthesis under neutral conditions. This protocol offers an easy access to a variety of polyols, cyanohydrins, linear alkylnitriles, by simply starting from alkyl- and arylaldehydes, KCN and an atmospheric pressure of CO2 .

CO2‐Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions**

CO2-Controlled Reductive Amination Reactions with NaBH4

CO2-Mediated Non-Destructive Cyanide Wastewater Treatment

A great variety of cuneiform texts have been found within the precincts of the high priest's building complex in ancient Ugarit. Some of the texts are letters, others are lexical texts and others again are ritual texts. The great epics of aqht and krt are best described as literary texts. Some of the texts, however, do not unambiguously belong to one group only: Some scholars would construe the Baal‐cycle as a ritual text or at least a text somehow connected with the cult performed in the temples; others would describe the Baal‐cycle as pure literature. Similarly the enigmatic text about Shachar and Shalim (abbreviated SS) apparently contains cultic and literary elements. Is this text then a cult‐text or a piece of literature? The aim of the article is to investigate if from the archaeological evidence we can add an argument to the on‐going debate about the Sitz im Leben of the Ugaritic Baal‐cycle: Were the clay tablets in the high priest's building distributed according to their content? The ans...

Allan R. Petersen

Papers

CO2‐Enabled Cyanohydrin Synthesis and Facile Iterative Homologation Reactions**

CO2-Controlled Reductive Amination Reactions with NaBH4

CO2-Mediated Non-Destructive Cyanide Wastewater Treatment

Where did Schaeffer find the clay tablets of the Ugaritic Baal‐cycle?