Synthesis of Conformationally Constrained Esters and Amines by Pd-Catalyzed α-Arylation of Hindered Substrates

The α-arylation of sterically hindered silyl ketene acetals (SKAs) with sterically hindered aryl bromides occurs efficiently using Pd[P(t-Bu)3]2 as the optimal catalyst and ZnF2 as a promoter. Less sensitive P(t-Bu)3-based catalysts could be also employed but showed a lower activity. The reaction showed a broad scope with regard to both coupling partners, including heteroaryl bromides and cyclic SKAs. It also proved to be scalable to multigram quantities, which allowed us to further transform the ester group and to access conformationally constrained benzyl- and phenethylamines, highly sought-after building blocks for the synthesis of new agrochemicals

Automated control system for the process of managing the procurement of raw materials used in steel making

The article presents a solution to the important problem of developing an automated control system for the process of purchasing raw materials used in metallurgical production. The system is based on an integrated approach that offers the solution that enables the performance of two main tasks: identifying the optimal lot size ordering and selecting a qualified supplier

Tri- and difluoromethoxylated N-based heterocycles − Synthesis and insecticidal activity of novel F3CO- and F2HCO-analogues of Imidacloprid and Thiacloprid

International audienc

The structure of the agrochemical fungicidal 4-Chloro-3-(3,5-dichloropheny)-1H-pyrazole, RPA 406194 and related compounds

The difficulties to obtain convenient monocrystals of the important fungicide RPA 406194 have been overcome by a combination of solid state 13C NMR, X-ray powder diffraction and molecular modeling. The compound, a 3-aryl tautomer, crystallizes forming infinite chains of molecules bonded by N–H· · ·N hydrogen bonds, leading to needle-shaped crystals. The tautomerism (equilibrium constant and energy barrier) of this compound in solution has been studied

A Rapid Access to Biaryl Ether Containing Macrocycles by Pairwise Use of Ugi 4CR and Intramolecular SNAr-Based Cycloetherification

An Ugi reaction promoted by ammonium chloride in aprotic solvent is documented here for the first time. From readily accessible starting materials, macrocycles with an endo aryl-aryl ether bond are synthesized in only two steps, Ugi four-component reaction (Ugi 4CR) and an intramol. SNAr reaction. The nitro group serves as an activator for the macrocyclization and provides a handle for the introduction of functional group diversity. For example, dipeptide amide I was obtained in an Ugi 4CR from isonitrile II, PhCHO, PhCH2NH2 and 3-hydroxyphenylacetic acid in the presence of NH4+Cl- in toluene at 0 Deg for 20 h. Cycloetherification of I took place in the presence of K2CO3 in DMF for 3 h to give macrocycle III in 80% yield. [on SciFinder (R)

Transition metal catalysis as methods for the elaboration of phosphorus heterocycles

International audienceA review. Among the heterocyclic compds., phosphorus heterocycles are still scarcely studied although they seem to hold promises in term of biol. potential. The last few years were the witness of remarkable developments and strategies for their synthesis. In this context, organometallic chem., using coupling reactions, C-C insertion or ring closing metathesis appears to be valuable and general approaches to achieve the formation of phosphorus heterocycles

Rapid and diverse route to natural product-like biaryl ether containing macrocycles

A two-step sequence involving an Ugi four-component reaction and an intramol. nucleophilic arom. substitution (SNAr) has been developed for the rapid access to biaryl-ether contg. macrocycles. For example, reacting heptanal with butylamine, (3-hydroxyphenyl)acetic acid, and isonitrile I in dry toluene in the presence of NH4Cl gave dipeptide II. II was then cyclized using an intramol. SNAr sequence to give cyclic ether III as a mixt. of 4 diastereomers. In the course of this study, we documented that ammonium chloride can promote the Ugi-4CR in non-polar aprotic solvent (toluene) without the interference of an alternative Passerini reaction. Solid phase synthesis of macrocycles by this two-step sequence was also developed using polymer (Wang resin) supported alpha -(4'-fluoro-3'-nitro)phenethyl isocyanoacetate as one of the inputs. [on SciFinder (R)

Le fluor en chimie organique : une montée en puissance

International audienceL’atome de fluor est exceptionnel tant les propriétés conférées aux molécules par sa présence sont intéressantes. En quelques années, l’introduction douce et sélective d’un ou de plusieurs atomes de fluor à l’aide de réactifs stables et non toxiques a connu un essor remarquable.Cet article décrit les avancées récentes en listant tour à tour les méthodes de fluoration, de trifluorométhylation, l’imagerie médicale du fluor 18 et se termine par les applications en sciences du vivant

Le fluor en chimie organique : une montée en puissance (Fluorine in organic chemistry gaining momentum)

International audienceL’atome de fluor est exceptionnel tant les propriétés conférées aux molécules par sa présence sont intéressantes. En quelques années, l’introduction douce et sélective d’un ou de plusieurs atomes de fluor à l’aide de réactifs stables et non toxiques a connu un essor remarquable.Cet article décrit les avancées récentes en listant tour à tour les méthodes de fluoration, de trifluorométhylation, l’imagerie médicale du fluor 18 et se termine par les applications en sciences du vivant

Xanthate-Mediated Incorporation of Quaternary Centers into Heteroarenes

International audienceThe xanthate-mediated addition of tertiary alkyl radicals to heteroarenes enabled the easy functionalization of heteroaromatic rings as well as more decorated structures, such as marketed drugs or agrochemicals. This work provides a synthetic tool for efficiently exploring the chemical space by allowing late-stage diversification with a high tolerance toward functional groups