Direct Diels-Alder reaction of chitin derived 3-acetamido-5-acetylfuran

The Diels-Alder (DA) reaction of biomass derived furans is an emerging technology for the preparation of new molecular entities and “drop-in” commodity chemicals. In this work we address the challenge of the direct use of electron-poor furanic platforms as dienes through the use of an unexplored chitin derived furan, 3-acetamido-5-acetylfuran (3A5AF). The 3-acetamido group promoted a remarkable increase in the kinetics of the DA allowing for the preparation of 7-oxanorbornenes (7-ONB) at 50 ºC. Partial hydrolysis of the enamide to hemi-acylaminals was possible upon fine tuning of the reaction conditions, disabling retro-DA processes. Finally, DA reaction of the reduced form of 3A5AF allowed quantitative formation of 7-ONB in aqueous condition after 10 minutes. Certanly these are the first steps for expanding the toolbox of chitin derived 3A5AF as diene.

COS-triggered Oxygen/Sulfur Exchange of Isatins: Chemoselective Synthesis of Functionalized Isoindigos and Spirothiopyrans via Self-condensation and Thio-Diels-Alder Reaction

Herein, we present the first organocatalytic oxygen/sulfur atom exchange reaction (O/S ER) of isatins by employing carbonyl sulfide (COS) as novel sulfuring reagent under mild reaction conditions. 8-Diazabicyclo[5.4.0] undec-7-ene (DBU),...

Construction of sulfur-containing compounds with anti-cancer stem cell activity using thioacrolein derived from garlic based on nature-inspired scaffolds

We reported for the first time that thioacroleinproduced by allicin, a major component in garlic, undergoes the regioselective sequential double Diels–Alder reaction.

Anthracene modified graphene for C60/C70 fullerenes capture and construction of energy storage materials

Graphene functionalized with dianthracene malonate was synthesized and used subsequently for construction of covalently bound graphene-fullerene hybrid nanomaterials. For this purpose, novel approach of Diels–Alder reaction of C60/C70 fullerene cores with anthracene moieties previously introduced onto graphene surface was successfully employed. Structure and composition of obtained graphene and its derivatives were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy. Obtained results revealed that both C60 and C70 fullerenes were found to be capable of formation desired Diels–Alder adducts, yielding products of different morphology. Capacitive properties of the synthesized energy storage nanomaterials were determined by means of cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) measurements, revealing that functionalization of graphene with C60 moieties enhances its energy storage properties.

Diels–Alder Cycloadditions of Bio-Derived Furans with Maleimides as a Sustainable «Click» Approach towards Molecular, Macromolecular and Hybrid Systems

This mini-review highlights the recent research trends in designing organic or organic-inorganic hybrid molecular, biomolecular and macromolecular systems employing intermolecular Diels–Alder cycloadditions of biobased, furan-containing substrates and maleimide dienophiles. The furan/maleimide Diels–Alder reaction is a well-known process that may proceed with high efficiency under non-catalytic and solvent-free conditions. Due to the simplicity, 100% atom economy and biobased nature of many furanic substrates, this type of [4+2]-cycloaddition may be recognized as a sustainable “click” approach with high potential for application in many fields, such as fine organic synthesis, bioorganic chemistry, material sciences and smart polymers development.

ASYMMETRIC ORGANOCATALYSIS

Dear Reader, Two basic reactions that were taught to us in the organic chemistry courses were the aldol condensation reaction and the Diels-Alder reaction. In aldol condensation, discovered by the French chemist Charles Wurtz in 1872, an enolate ion reacts with a carbonyl compound in the presence of an acid/ base catalyst to form a β-hydroxy aldehyde or a β-hydroxy ketone, usually followed by dehydration to give a conjugated enone. If the enolate ion and the carbonyl group are present in the same molecule, then the aldol reaction is intramolecular. It is an extremely useful carbon-carbon bond-forming reaction. The Diels-Alder reaction, discovered in 1928 by the German chemist Otto Diels and his student Kurt Alder, is the reaction between a conjugated diene and an alkene, a so-called dienophile, to form an unsaturated six-membered ring. It is called a cycloaddition reaction, since the reaction involves the formation of a cyclic product via a cyclic transition state. Uncatalysed Diels– Alder reactions usually require extended reaction times at elevated pressures and temperatures with the formation of by-products, hence various catalysts are employed. The Diels-Alder reaction also has great industrial relevance and the discoverers were crowned with the 1950 Nobel Prize in Chemistry. The aldol condensation reaction and the Diels-Alder reaction typically require catalysts, basically Brønsted acids, Brønsted bases, Lewis acids or Lewis bases. This triggered the minds of Dr. David MacMillan and Dr. Benjamin List for different reasons at different locations in USA around not so different times, more than twenty years ago, culminating in their being jointly awarded the Nobel Prize in Chemistry for this year.