Author
Huck K. Grover
Other affiliations: University of California, Berkeley, University College West
Bio: Huck K. Grover is an academic researcher from University of Western Ontario. The author has contributed to research in topics: Cyclopropane & Reactivity (chemistry). The author has an hindex of 8, co-authored 13 publications receiving 662 citations. Previous affiliations of Huck K. Grover include University of California, Berkeley & University College West.
Papers
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TL;DR: This review summarizes research directed towards the formation of carbocyclic adducts from donor-acceptor cyclopropanes and focuses on annulation and cycloaddition reactions mediated by Lewis or protic acid, bases, or thermal conditions.
Abstract: This review summarizes research directed towards the formation of carbocyclic adducts from donor–acceptor cyclopropanes. The focus of the review is on annulation and cycloaddition reactions (both inter- and intramolecularly) mediated by Lewis or protic acid, bases, or thermal conditions. Rearrangements resulting in carbocycles and those reactions mediated by transition metal catalysis have been excluded.
366 citations
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TL;DR: A disparate synthetic approach to complex terpenes whereby simple prenyl-derived chains are cyclized using radical, rather than cationic, reaction pathways, which lays the foundation for efficient synthesis of terpenoid ring systems of interest in medicinal research, particularly those that have been historically challenging to access.
Abstract: Cyclase enzymes weave simple polyprenyl chains into the elaborate polycyclic ring systems of terpenes, a sequence that is often difficult to emulate under abiotic conditions. Here we report a disparate synthetic approach to complex terpenes whereby simple prenyl-derived chains are cyclized using radical, rather than cationic, reaction pathways. This strategy allowed us to efficiently forge the intricate 5-8-5 fused ring systems found in numerous complex natural product classes and also enabled a nine-step total synthesis of (–)-6- epi- ophiobolin N, a member of the large family of cytotoxic ophiobolin sesterterpenes. A small-molecule thiol catalyst was found to override the inherent diastereoselectivity observed during a reductive radical cascade cyclization process. This work lays the foundation for efficient synthesis of terpenoid ring systems of interest in medicinal research, particularly those that have been historically challenging to access.
108 citations
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TL;DR: A Zn(NTf(2))(2) catalyzed tandem reaction consisting of a nucelophilic ring opening of 1,1-cyclopropanediesters by 2-alkynyl indoles followed by a Conia-ene ring closure results in the efficient one-step synthesis of tetrahydrocarbazoles.
98 citations
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TL;DR: Cyclopropane hemimalonates, when treated with sodium azide, undergo a tandem ring-opening decarboxylation to produce γ-azidobutyric acids in good yields.
Abstract: Cyclopropane hemimalonates, when treated with sodium azide, undergo a tandem ring-opening decarboxylation to produce γ-azidobutyric acids in good yields. These adducts were hydrogenated to form γ-aminobutyric acid (GABA) methyl esters.
79 citations
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TL;DR: Under microwave irradiation, cyclopropane hemimalonates undergo rapid conversion to butanolides in the presence of inorganic salts with an unprecedented retention of stereochemistry, which has been applied to the total synthesis of the naturally occurring (R)-dodecan-4-olide.
63 citations
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947 citations
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TL;DR: This Review highlights the appropriate tools for successfully employing donor-acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
Abstract: The effective use of ring strain has been applied to considerable advantage for the construction of complex systems. The focus here is directed towards cyclopropanes as building blocks for organic synthesis. Although thermodynamics should take the side of synthetic chemists, only a specific substitution pattern at the cyclopropane ring allows for particularly mild, efficient, and selective transformations. The required decrease in the activation barrier is achieved by the combined effects of vicinal electron-donating and electron-accepting moieties. This Review highlights the appropriate tools for successfully employing donor–acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
805 citations
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TL;DR: This Perspective illustrates the defining characteristics of free radical chemistry, beginning with its rich and storied history, and studies from the laboratory are discussed along with recent developments emanating from others in this burgeoning area.
Abstract: This Perspective illustrates the defining characteristics of free radical chemistry, beginning with its rich and storied history. Studies from our laboratory are discussed along with recent developments emanating from others in this burgeoning area. The practicality and chemoselectivity of radical reactions enable rapid access to molecules of relevance to drug discovery, agrochemistry, material science, and other disciplines. Thus, these reactive intermediates possess inherent translational potential, as they can be widely used to expedite scientific endeavors for the betterment of humankind.
628 citations
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TL;DR: Key advances in terpenoid cyclase structural and chemical biology are reviewed, focusing mainly on ter penoid cyclases and related prenyltransferases for which X-ray crystal structures have informed and advanced the authors' understanding of enzyme structure and function.
Abstract: The year 2017 marks the twentieth anniversary of terpenoid cyclase structural biology: a trio of terpenoid cyclase structures reported together in 1997 were the first to set the foundation for understanding the enzymes largely responsible for the exquisite chemodiversity of more than 80000 terpenoid natural products. Terpenoid cyclases catalyze the most complex chemical reactions in biology, in that more than half of the substrate carbon atoms undergo changes in bonding and hybridization during a single enzyme-catalyzed cyclization reaction. The past two decades have witnessed structural, functional, and computational studies illuminating the modes of substrate activation that initiate the cyclization cascade, the management and manipulation of high-energy carbocation intermediates that propagate the cyclization cascade, and the chemical strategies that terminate the cyclization cascade. The role of the terpenoid cyclase as a template for catalysis is paramount to its function, and protein engineering can...
562 citations
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TL;DR: This review summarizes research directed towards the formation of carbocyclic adducts from donor-acceptor cyclopropanes and focuses on annulation and cycloaddition reactions mediated by Lewis or protic acid, bases, or thermal conditions.
Abstract: This review summarizes research directed towards the formation of carbocyclic adducts from donor–acceptor cyclopropanes. The focus of the review is on annulation and cycloaddition reactions (both inter- and intramolecularly) mediated by Lewis or protic acid, bases, or thermal conditions. Rearrangements resulting in carbocycles and those reactions mediated by transition metal catalysis have been excluded.
366 citations