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Krishna P. Kaliappan

Bio: Krishna P. Kaliappan is an academic researcher from Indian Institute of Technology Bombay. The author has contributed to research in topics: Enyne metathesis & Ring-closing metathesis. The author has an hindex of 23, co-authored 115 publications receiving 1454 citations. Previous affiliations of Krishna P. Kaliappan include Duke University & Indian Institute of Science.


Papers
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Journal ArticleDOI
TL;DR: This Focus Review summarizes the recent advances in one particular field: the copper-catalyzed C-N bond formation reactions via C-H bond functionalization to furnish a comprehensive range of nitrogen heterocycles.
Abstract: Nitrogen-containing heterocycles have found remarkable applications in natural product research, material sciences, and pharmaceuticals. Although the synthesis of this interesting class of compounds attracted the interest of generations of organic chemists, simple and straightforward assembly methods based on transition-metal catalysis have regularly been elusive. The recent advancements in the development of C-H functionalization have helped in accomplishing the synthesis of a variety of complex heterocycles from simple precursors. This Focus Review summarizes the recent advances in one particular field: the copper-catalyzed C-N bond formation reactions via C-H bond functionalization to furnish a comprehensive range of nitrogen heterocycles. Applicability and synthetic feasibility of a particular reaction represent major requirements for the inclusion in this review.

105 citations

Journal ArticleDOI
TL;DR: An enantioselective route for the synthesis of oxatetracyclic core of platensimycin is reported for the first time using a 5-exo-trig cyclization followed by intramolecular etherification as key reactions.

71 citations

Journal ArticleDOI
TL;DR: A versatile strategy involving a sequential intermolecular enyne metathesis of C-alkynyl glycosides with ethylene, Diels-Alder, and aromatization reactions is successfully developed to provide a range of C -aryl Glycosides.

62 citations

Journal ArticleDOI
TL;DR: A direct one-pot Cu-catalyzed biomimetic oxidation of methyl ketones to pharmaceutically important N-heterocyclic amides is reported, and the extensive mechanistic studies suggest that this reaction follows the Luciferin-Luciferase-like pathway.

58 citations

Journal ArticleDOI
TL;DR: Though both these antibiotics are structurally related, they work by slightly different mechanisms and target different enzymes conserved in the bacterial fatty acid biosynthesis, which is essential for the survival of bacteria.
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.

58 citations


Cited by
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Journal Article
TL;DR: In this article, a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators were developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of 3D micro-optical and micromechanical structures, including photonic-bandgap-type structures.
Abstract: Two-photon excitation provides a means of activating chemical or physical processes with high spatial resolution in three dimensions and has made possible the development of three-dimensional fluorescence imaging, optical data storage, and lithographic microfabrication. These applications take advantage of the fact that the two-photon absorption probability depends quadratically on intensity, so under tight-focusing conditions, the absorption is confined at the focus to a volume of order λ3 (where λ is the laser wavelength). Any subsequent process, such as fluorescence or a photoinduced chemical reaction, is also localized in this small volume. Although three-dimensional data storage and microfabrication have been illustrated using two-photon-initiated polymerization of resins incorporating conventional ultraviolet-absorbing initiators, such photopolymer systems exhibit low photosensitivity as the initiators have small two-photon absorption cross-sections (δ). Consequently, this approach requires high laser power, and its widespread use remains impractical. Here we report on a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators. Two-photon excitable resins based on these new initiators have been developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of three-dimensional micro-optical and micromechanical structures, including photonic-bandgap-type structures.

1,833 citations

Journal ArticleDOI
TL;DR: This Review comprehensively highlights recent advances in intra- and intermolecular C-H amination reactions utilizing late transition metal-based catalysts using mechanistic scaffolds and types of reactions.
Abstract: Catalytic transformation of ubiquitous C–H bonds into valuable C–N bonds offers an efficient synthetic approach to construct N-functionalized molecules. Over the last few decades, transition metal catalysis has been repeatedly proven to be a powerful tool for the direct conversion of cheap hydrocarbons to synthetically versatile amino-containing compounds. This Review comprehensively highlights recent advances in intra- and intermolecular C–H amination reactions utilizing late transition metal-based catalysts. Initial discovery, mechanistic study, and additional applications were categorized on the basis of the mechanistic scaffolds and types of reactions. Reactivity and selectivity of novel systems are discussed in three sections, with each being defined by a proposed working mode.

1,481 citations

Journal ArticleDOI
TL;DR: A comprehensive overview on first row transition metal catalysts for C-H activation until summer 2018 is provided.
Abstract: C–H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material sciences, crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these C–H functionalizations required precious 4d or 5d transition metal catalysts. Given the cost-effective and sustainable nature of earth-abundant first row transition metals, the development of less toxic, inexpensive 3d metal catalysts for C–H activation has gained considerable recent momentum as a significantly more environmentally-benign and economically-attractive alternative. Herein, we provide a comprehensive overview on first row transition metal catalysts for C–H activation until summer 2018.

1,417 citations

Journal ArticleDOI
TL;DR: The review covers the knowledge on photoremovable protecting groups and includes all relevant chromophores studied in the time period of 2000–2012 and the most relevant earlier works are discussed.
Abstract: The review covers the knowledge on photoremovable protecting groups and includes all relevant chromophores studied in the time period of 2000–2012; the most relevant earlier works are also discussed.

1,274 citations