Search results for "Organic synthesi"
showing 10 items of 83 documents
Modern Electrochemical Aspects for the Synthesis of Value‐Added Organic Products
2017
The use of electricity instead of stoichiometric amounts of oxidizers or reducing agents in synthesis is very appealing for economic and ecological reasons, and represents a major driving force for research efforts in this area. To use electron transfer at the electrode for a successful transformation in organic synthesis, the intermediate radical (cation/anion) has to be stabilized. Its combination with other approaches in organic chemistry or concepts of contemporary synthesis allows the establishment of powerful synthetic methods. The aim in the 21st Century will be to use as little fossil carbon as possible and, for this reason, the use of renewable sources is becoming increasingly impo…
Zirconium & Hafnium: Organometallic ChemistryBased in part on the article Zirconium & Hafnium: Organometallic Chemistry by Bernard Gautheron,…
2006
This review considers the main aspects of organometallic chemistry of zirconium and hafnium during the last 10 years. It is complementary to the first edition of Encyclopedia of Inorganic Chemistry. The material is presented in two major parts divided in five and three sections respectively. The first part is devoted to syntheses: the first section, by far the largest, covers in a systematic manner bis and mono cyclopentadienyl complexes with +4, +3, and +2 oxidation states and more especially constrained-geometry (CG) complexes, cationic complexes, and anionic or zwitterionic 18-electron complexes; unusual coordination geometries at carbon stabilized by group 4 metallocenes are presented i…
Recent Developments in the Chiral Brønsted Acid-catalyzed Allylboration Reaction with Polyfunctionalized Substrates
2016
Asymmetric allylboration has played a central role in organic synthesis ever since the pioneering work by Hoffman and Brown, having found applications in the total synthesis of many natural products. A new dawn for this 40 year-old reaction occurred with the beginning of the new century when the first catalytic asymmetric methods came into play. In less than one decade, several methodologies, able to achieve the desired homoallylic alcohols with ee ranges in the high 90s, were developed. Among them, in the present account, we will disclose our contribution to the development of the chiral binolphosphoric-derived BrOnsted acid-catalyzed allylboration of aldehydes originally reported by Antil…
MoVReagents in Organic Synthesis
2016
The use of MoV reagents, and in particular MoCl5, in organic synthesis is surveyed. The oxidative treatment of aromatic substrates is the most common application. The unique properties of these reagents are due to their high oxidative power combined with exquisite Lewis acid properties. In several examples MoV reagents outperform other common oxidative coupling reagents. C–C bond formation through inter- and intramolecular oxidative coupling can lead to selective formation of five- to eight-membered ring systems. Mechanistic investigations of the courses of reactions involving MoV reagents and aromatic substrates indicate that radical cations are initially formed, entering the oxidative cou…
Iron-Catalyzed C(sp2)–C(sp3) Cross-Coupling of Chlorobenzenesulfonamides with Alkyl Grignard Reagents: Entry to Alkylated Aromatics
2018
Alkylated benzosulfonamides are compounds of high importance in organic synthesis, including the production of pharmaceuticals, agrochemicals, and plasticizers. We report the iron-catalyzed C(sp2)–C(sp3) cross-coupling of chlorobenzosulfonamides with alkyl Grignard reagents under mild and sustainable conditions. Electronically and sterically varied benzosulfonamides as well as challenging alkyl organometallics containing β-hydrogen afford alkylated benzosulfonamides in high to excellent yields. Sulfonamide represents the most reactive activating group for iron-catalyzed cross-coupling. The process affords alkylated benzenesulfonamides poised for medicinal chemistry applications and traceles…
Base-catalyzed isomerization of 2-isoxazolines enables a two-step enantioselective synthesis of β-hydroxynitriles from enals.
2010
The asymmetric synthesis of β-hydroxynitriles remains a challenge in organic synthesis. Herein we report a convenient synthesis of β-hydroxynitriles from enantiomerically enriched 3-unsubstituted 2-isoxazolines via a base-catalyzed ring-opening reaction that takes place without loss of enantiopurity. In combination with organocatalytic enantioselective synthesis of 3-unsubstituted 2-isoxazolines, the ring-opening enables a short 2-step synthesis of β-hydroxynitriles from α,β-unsaturated aldehydes in high enantiomeric purity.
Hydrophobically Modified Halloysite Nanotubes as Reverse Micelles for Water-in-Oil Emulsion.
2015
An easy strategy to obtain inorganic reverse micelles based on halloysite nanotubes (HNTs) and alkyltrimethylammonium bromides has been developed. The selective modification of the HNTs external surface with cationic surfactants endows to generate tubular nanostructures with a hydrophobic shell and a hydrophilic cavity. The influence of the surfactants alkyl chain on the HNTs functionalization degree has been investigated. The dynamic behavior of the surfactant/HNT hybrids in solvents with variable polarity has been correlated to their affinity toward hydrophobic media explored through partition experiments. The water-in-oil emulsion is able to solubilize copper sulfate, proving the incorpo…
Anodic Dehydrogenative Cyanamidation of Thioethers: Simple and Sustainable Synthesis of N‐Cyanosulfilimines
2021
Abstract A novel and very simple to perform electrochemical approach for the synthesis of several N‐cyanosulfilimines in good to excellent yields was established. This method provides access to biologically relevant sulfoximines by consecutive oxidation using electro‐generated periodate. This route can be easily scaled‐up to gram quantities. The S,N coupling is carried out at an inexpensive carbon anode by direct oxidation of sulfide. Therefore, the designed process is atom economic and represents a new “green route” for the synthesis of sulfilimines and sulfoximines.
Soluble polymers in organic synthesis
1982
The end function of polyethylene glycol was transferred to the tertiary alcohol for use as acid labile, solubilizing protecting group in peptide synthesis.
Carbon nitride as photocatalyst in organic selective transformations
2020
Abstract Graphitic carbon nitride (g-C3N4) is a metal-free conjugated polymer which has become a new research hotspot in photocatalysis. It can be used for solar energy exploitation like in solar energy organic synthesis, one of the most new and appealing green applications of heterogeneous photocatalysis. This chapter resumes the state-of-the-art and progresses in the application of heterogeneous visible light photocatalysis in organic selective transformations by using C3N4 as photocatalyst.