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.

Evaluation of Chelation Effects Operative during Diastereoselective Addition of the Allylindium Reagent to 2- and 3-Hydroxycyclohexanones in Aqueous, Organic, and Mixed Solvent Systems

Abstract: The unprotected 2- and 3-hydroxycyclohexanones 1−8 were prepared by methods that skirted as much as possible their proclivity for α-ketol rearrangement (where the possibility for such isomerization...

Synthesis and molecular structure of belted spirocyclic tetrahydrofurans, a new class of preorganized hosts for cations

Abstract: The preparation and binding properties of spirocyclic tetrahydrofurans 7-11 are described. The condensition of cyclopentanone with 5-lithio-2,3-dihydrofuran (12) provided an alcohol which readily rearranged to ketone 14 under acidic condition. »Capping« of the carbonyl group in 14 so as to generate a second spiro tetrahydrofuran subunit gave rise to 7 and 8. Starting with cyclobutanone, 2-fold ring expansion involving 12 provided the key reaction leading to 22 and 23, which were »capped« as before

Impact of substituent modifications on the atropselectivity characteristics of an anionic oxy-Cope ring expansion

Abstract: The phenomenon of atropisomerism is critically examined in the tricyclic E, syn, up enolates derived from anionic oxy-Cope rearrangement of 1-vinyl-2-cyclohexenyl-7,7-dimethyl-exo-norbornan-2-ols, as well as the ketones derived from their protonation and methylation. In all cases studied, the [3,3] sigmatropic shift proceeds with 100% stereoselectivity via the endo-chair transition-state option. The E and syn stereochemistry is established during chirality transfer at this stage. The «oxygen-up» conformation stems directly from the structural features inherent in the starting alcohols. In the unsubstituted example and with certain substitution pattrerns in the original cyclohexene ring, the E, syn, up enolates are seen to be thermodynamically unstable relative to their E, syn, down atropisomers, such that products results exclusively by electrophilic capture of the latter. By suitable substitution, the barrier to this preequilibrium can be sufficiently heightened so that products resulting from the E, syn, up species can be obtained

Synthetic studies on basmane diterpenes. Enantiospecific total synthesis of (+)-7,8-epoxy-2-basmen-6-one by Claisen ring expansion

Abstract: Synthese du compose du titre a partir d'5-isopropyl-2-methylcyclopent-1-ene carbaldehyde via la transposition Claisen d'un derive de cyclopenta pyrane en derive de cyclopenta cyclooctene

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.