Current Organic Chemistry - Volume 24, Issue 13, 2020

Michael reaction is the nucleophilic addition of active methylene compounds to conjugated olefins, resultantly affording a variety of biologically active scaffolds with high enantiopurity. To improve the reaction yield, as well as enantioselectivity of the product, a variety of catalysts (amine-based catalysts, bifunctional L-proline amides, bifunctional squaramides, chiral ionic liquids, cinchona alkaloids, enzymes, indolinols, metal catalysts, peptide derived catalytic system, phase transfer catalysts, pyrrolidine based organocatalysts) have been investigated by a different era of chemists. Besides this, different methodologies have been developed to improve reaction yield and enantioselectivity of the targeted products with low catalyst loading. This review article provides a concise overview of the catalysts applied recently by different scientists in the Michael addition reaction. Moreover, current strategies and potential applications of this reaction have also been illustrated in this review.

The following review article provides an overview of DHA chemistry, with specific confirmation based on major historical developments and progress mainly made over the last two decenniums. It is our hope this review serves as a valuable treasure to those interested in the 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (DHA) chemistry, and helps impact future advancements.

Pyrazole is an imperative heterocyclic molecule in the synthetic and medicinal fields. Pyrazole is stable compound that is particularly used in pharmaceutical applications (i.e., anticancer, antifungal, antiviral, antimicrobial and antioxidant) and electronic industries. This review depicted the synthesis of pyrazoles derivatives by employing chalcone derivatives as a starting material via one and two-pot strategies. The one-pot strategy is an exclusive method for chalcone cyclization and oxidation, while two-pot strategy is reported through the preparation of chalcone derivatives, i.e., pyrazoline, hydrazone and bromochalcone prior to the synthesis of pyrazole. One-pot strategy is frequently reported for pyrazole synthesis purposes due to unique, stable, reactive and well-known chalcone reactants having easy handing then two-pot strategy. This review is momentous in organic chemistry, especially synthesis related to pyrazole and drug industry.

The article reviews the research progress in the preparation of polycaprolactone through the ring-opening polymerization of ε-caprolactone initiated by biopolymers in recent years. The structure characteristics of starch, cellulose, chitosan, polyhydroxyalkanoates, and polylactic acid, the reaction mechanism, the preparation method, and the application of ε-caprolactone are introduced. Finally, the future development of new polycaprolactone copolymers is prospected.

In this work, a series of π-conjugated isoquinoline derivatives, bearing diverse aryl groups at the 3-position, were synthesized in a facile and straightforward manner. A Pdcatalyzed protocol, the Suzuki-Miyaura coupling of 3-bromoisoquinoline and different aryl boronic acids, was applied, and the structures of the resulting target compounds were determined by 1H-NMR, 13C-NMR, and HRMS. Furthermore, the photophysical properties of these compounds were investigated. Distinct halochromic properties were revealed for them, which exhibited UV emissions in ethanol but visible emissions in an acidic solution.