Leo A. Paquette

Bio: Leo A. Paquette is an academic researcher from Ohio State University. The author has contributed to research in topics: Ring (chemistry) & Total synthesis. The author has an hindex of 36, co-authored 484 publications receiving 6021 citations. Previous affiliations of Leo A. Paquette include Heidelberg University.

The Carbohydrate-Sesquiterpene Interface. A Zirconocene-Mediated Synthesis­ of (+)-Epiafricanol from d-Glucose

Abstract: A total synthesis of (+)-epiafricanol (6) has been readily achieved from D-glucose. The tricyclic alcohol target was arrived at by first forming methyl 6-O-benzyl-2-deoxy-2-C-methyl-α-D-altropyranoside (12) and convertingthis intermediate into methyl 2-C-methyl-2,3,4-trideoxy-α-D-threo-hexopyranoside (14). There followed a series of steps resulting in extension of the side chain to give the isopropenyl pyranoside 9. This advanced intermediate was subjected to zirconocene-promoted ring contraction, which gave rise to 8 and set the stage for conversion to 7. This tertiary carbinol was transformed into 6 by sequential ring-closing metathesis and stereodirected Simmons-Smith cyclopropanation.

Electrostatic modulation of hydroxyl group ionization in acidic media. Evidence for the competitive operation of intramolecular SN2 reactions

Abstract: The acid-catalyzed cyclodehydration of the cis and trans isomers of 2-substituted 1-(3-hydroxypropyl)cyclohexanols results in the formation of spirocyclic tetrahydrofurans. The stereochemical course of these reactions is highly varied, ranging from a dominant preference for retention when R=OCH 3 to modestly favored inversion when R=CH 3 . Experiments with 18 O-labeled diols show that in the methoxyl series most of the isotope is retained irrespective of relative stereochemistry. On the other hand, the pair of phenyl-substituted isomers responds by losing approximately 50% of the label

Chiral reagents for asymmetric synthesis

Abstract: Preface. Introduction. Recent Review Articles and Monographs. Organic Synthesis Procedures Featuring Chiral, Non-Racemic Reagent Preparation. List of Contributors. Reagent Formula Index. Subject Index.

Multifaceted consequences of holding two [8]annulene rings face-to-face. Synthesis, structural characteristics, and reduction behavior of [22](1,5)cyclooctatetraenophane

Abstract: The doubly-decked [8]annulene 11 has been prepared in 13 steps from octahydro 3a,9a-propenocyclopentacycloocten-2,11-dione. The scheme takes advantage of the annulating capacity of the Cook-Weiss reaction and the ability of semibullvalenes to undergo thermal isomerization to cyclooctatetraenes. Bis(semibullvalene) is both conformationally dynamic and subject to very rapid Cope rearrangement. The energetics of inversion within its interconnective cyclooctane ring have been elucidated by variable-temperature 1 H NMR spectroscopy

C-H bond functionalization: emerging synthetic tools for natural products and pharmaceuticals

Abstract: The direct functionalization of C-H bonds in organic compounds has recently emerged as a powerful and ideal method for the formation of carbon-carbon and carbon-heteroatom bonds. This Review provides an overview of C-H bond functionalization strategies for the rapid synthesis of biologically active compounds such as natural products and pharmaceutical targets.

Palladium-catalyzed cross-coupling reactions in total synthesis.

Abstract: In studying the evolution of organic chemistry and grasping its essence, one comes quickly to the conclusion that no other type of reaction plays as large a role in shaping this domain of science than carbon-carbon bond-forming reactions. The Grignard, Diels-Alder, and Wittig reactions are but three prominent examples of such processes, and are among those which have undeniably exercised decisive roles in the last century in the emergence of chemical synthesis as we know it today. In the last quarter of the 20th century, a new family of carbon-carbon bond-forming reactions based on transition-metal catalysts evolved as powerful tools in synthesis. Among them, the palladium-catalyzed cross-coupling reactions are the most prominent. In this Review, highlights of a number of selected syntheses are discussed. The examples chosen demonstrate the enormous power of these processes in the art of total synthesis and underscore their future potential in chemical synthesis.

Organic Reactions in Aqueous Media with a Focus on Carbon−Carbon Bond Formations: A Decade Update

Abstract: 4.2.8. Reductive Coupling 3109 5. Reaction of Aromatic Compounds 3110 5.1. Electrophilic Substitutions 3110 5.2. Radical Substitution 3111 5.3. Oxidative Coupling 3111 5.4. Photochemical Reactions 3111 6. Reaction of Carbonyl Compounds 3111 6.1. Nucleophilic Additions 3111 6.1.1. Allylation 3111 6.1.2. Propargylation 3120 6.1.3. Benzylation 3121 6.1.4. Arylation/Vinylation 3121 6.1.5. Alkynylation 3121 6.1.6. Alkylation 3121 6.1.7. Reformatsky-Type Reaction 3122 6.1.8. Direct Aldol Reaction 3122 6.1.9. Mukaiyama Aldol Reaction 3124 6.1.10. Hydrogen Cyanide Addition 3125 6.2. Pinacol Coupling 3126 6.3. Wittig Reactions 3126 7. Reaction of R,â-Unsaturated Carbonyl Compounds 3127

Cascade reactions in total synthesis.

Abstract: The design and implementation of cascade reactions is a challenging facet of organic chemistry, yet one that can impart striking novelty, elegance, and efficiency to synthetic strategies. The application of cascade reactions to natural products synthesis represents a particularly demanding task, but the results can be both stunning and instructive. This Review highlights selected examples of cascade reactions in total synthesis, with particular emphasis on recent applications therein. The examples discussed herein illustrate the power of these processes in the construction of complex molecules and underscore their future potential in chemical synthesis.