Kalanidhi Palanichamy

Bio: Kalanidhi Palanichamy is an academic researcher from Indian Institute of Technology Bombay. The author has contributed to research in topics: Moiety & Platensimycin. The author has an hindex of 5, co-authored 9 publications receiving 153 citations.

Discovery and Syntheses of “Superbug Challengers”—Platensimycin and Platencin

Abstract: Bacteria have developed resistance to almost all existing antibiotics known today and this has been a major issue over the last few decades. The search for a new class of antibiotics with a new mode of action to fight these multiply-drug-resistant strains, or “superbugs”, allowed a team of scientists at Merck to discover two novel antibiotics, platensimycin and platencin using advanced screening strategies, as inhibitors of bacterial fatty acid biosynthesis, which is essential for the survival of bacteria. Though both these antibiotics are structurally related, they work by slightly different mechanisms and target different enzymes conserved in the bacterial fatty acid biosynthesis. This Focus Review summarizes the synthetic and biological aspects of these natural products and their analogues and congeners.

Application of an enyne metathesis/Diels-Alder cycloaddition sequence: a new versatile approach to the syntheses of C-aryl glycosides and spiro-C-aryl glycosides.

Abstract: An efficient approach for the synthesis of a variety of C-aryl and spiro-C-aryl glycosides is described. This diversity-oriented strategy employed here relies on a sequential enyne metathesis to generate the 1,3-diene moiety and Diels–Alder reaction with different dienophiles followed by aromatisation. Whereas cross-enyne metathesis with ethylene gas is used to install the 1,3-diene moiety at the anomeric centre for the synthesis of C-aryl glycosides, an intramolecular enyne metathesis on the sugar enyne is performed to generate the 1,3-diene moiety for the synthesis of spiro-C-aryl glycosides. Efforts to extend this strategy to the synthesis of the core structure of natural C-aryl glycoside gilvocarcin are also described. A combination of both C-aryl and spiro-C-aryl glycosides in the same moiety to combine the features thereof has also been accomplished. A tandem enyne metathesis/Diels–Alder reaction/aromatisation has also been attempted to directly access the C-aryl glycosides in one pot albeit in low yield.

A radical cyclization approach to the formal total syntheses of platencin

Abstract: Two different strategies leading to formal total syntheses of platencin are described. The first strategy involving Claisen rearrangement and radical cyclization provides a rapid access to the core structure of platencin, and also use minimum protective-group operations. The second strategy, a protecting group-free route, utilizes a 6-exo-trig radical cyclization and aldol condensation as key steps leading to the formal synthesis of platencin.

An Efficient Copper-Catalyzed Three-Component Synthesis of 3-C-Linked Glycosyl Iminocoumarins

Abstract: An efficient general strategy was developed for the synthesis of previously unknown 3-C-linked glycosyl iminocoumarins. The strategy involves a copper-catalyzed multicomponent reaction of sugar-derived alkynes with tosyl azide and salicylaldehyde to give a diverse array of glycosyl iminocoumarins in good yields. These compounds can serve as appropriate precursors for the synthesis of the corresponding coumarin 3-C-glycosides.

Synthesis of Saturated Six-Membered Ring Lactones

Abstract: The δ-lactone moiety is a common structural framework found in many natural products that exhibit interesting biological properties. This review details a collection of various selected methods developed for the synthesis of saturated δ-lactones. Synthesis of unsaturated δ-lactones and manipulation thereof to saturated δ-lactones are not covered in this review.

Recent Advances in the Chemical Synthesis of C-Glycosides

Abstract: Advances in the chemical synthesis of C-pyranosides/furanosides are summarized, covering the literature from 2000 to 2016. The majority of the methods take advantage of the construction of the glycosidic C—C bond. These C-glycosylation methods are categorized herein in terms of the glycosyl donor precursors, which are commonly used in O-glycoside synthesis and are easily accessible to nonspecialists. They include glycosyl halides, glycals, sugar acetates, sugar lactols, sugar lactones, 1,2-anhydro sugars, thioglycosides/sulfoxides/sulfones, selenoglycosides/telluroglycosides, methyl glycosides, and glycosyl imidates/phosphates. Mechanistically, C-glycosylation reactions can involve glycosyl electrophilic/cationic species, anionic species, radical species, or transition-metal complexes, which are discussed as subcategories under each type of sugar precursor. Moreover, intramolecular rearrangements, such as the Claisen rearrangement, Ramberg–Backlund rearrangement, and 1,2-Wittig rearrangement, which usuall...

Monocyclic phenolic acids; hydroxy- and polyhydroxybenzoic acids: occurrence and recent bioactivity studies.

Abstract: Among the wide diversity of naturally occurring phenolic acids, at least 30 hydroxy- and polyhydroxybenzoic acids have been reported in the last 10 years to have biological activities The chemical structures, natural occurrence throughout the plant, algal, bacterial, fungal and animal kingdoms, and recently described bioactivities of these phenolic and polyphenolic acids are reviewed to illustrate their wide distribution, biological and ecological importance, and potential as new leads for the development of pharmaceutical and agricultural products to improve human health and nutrition

Phthalides and Phthalans: Synthetic Methodologies and Their Applications in the Total Synthesis

Abstract: 1. Phthalides A 1.

Small organometallic compounds as antibacterial agents.

Abstract: The emergence of bacterial resistance to commercial antibiotics is an issue of global importance. During the last two decades, the number of antibacterial agents that have been discovered and introduced into the market has steadily declined and failed to meet the challenges posed by rapidly increasing resistance of the pathogens against common antibacterial drugs. The development of new classes of compounds to control the virulence of the pathogens is therefore urgently required. This perspective describes the historical development in brief and recent advances on the preparation of small organometallic compounds as new classes of antibacterial agents with potential for clinical development.

Navigating the Chiral Pool in the Total Synthesis of Complex Terpene Natural Products

Abstract: The pool of abundant chiral terpene building blocks (i.e., “chiral pool terpenes”) has long served as a starting point for the chemical synthesis of complex natural products, including many terpenes themselves. As inexpensive and versatile starting materials, such compounds continue to influence modern synthetic chemistry. This review highlights 21st century terpene total syntheses which themselves use small, terpene-derived materials as building blocks. An outlook to the future of research in this area is highlighted as well.