https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

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.

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

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.

Palladium-catalyzed cross-coupling reactions in total synthesis.

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

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

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.

Cascade reactions in total synthesis.

Geometrically and optically pure (3R,5E)- and (3R,5Z)-1,5-heptadien-3-ols undergo anionic oxy-Cope rearrangement under the exclusice control of oxyanion orientation with a 58-64% preference for equatorial oxygen. Six semicyclic dienols have also been synthesized where the preferred oxyanion-driven sigmatropic rearrangement pathway is obligatorily pitted against π-facial biases offered by 4-tert-butylcyclohexenyl, norbornenyl, and camphenyl rings. These rearrangements therefore offer especially stringent tests of those factors that control the level and direction of chirality transfer. The data show the oxyanion to disfavor becoming involved in 1,3-diaxial relationships

Relevance of oxyanion stereochemistry to chirality transfer in anionic oxy-cope rearrangements

Bei Photooxidationen der Isopropylidennorbornene (I) bestimmen wahrscheinlich hauptsachlich zwei Mechanismen das anti:syn-Verhaltnis im Produktgemisch.

Electronic control of stereoselectivity. 1. Singlet oxygen and related electrophilic additions to aryl-substituted 7-isopropylidenebenzonorbornenes

A program directed toward an asymmetric synthesis of pestalotiopsin A is described. The routing begins with the dextrorotatory cyclobutanol 37, which is combined with the enantiomerically defined building blocks ent-15 and 16. These units are incorporated via stereocontrolled 1,2-nucleophilic addition and anti-aldol coupling, respectively. With these straightforward reactions accomplished, the sequel involved the introduction of terminal double bonds in anticipation of the fact that the (E)-cyclononene substructure could be realized by ring-closing metathesis. This central issue was evaluated with several diene substrates and catalysts, all to no avail. Cross-metathesis experiments involving 59 and 65 with the functionalized heptene 60 revealed a marked difference in the inability to engage interaction with the ruthenium catalyst. This awkwardness could not be skirted.

Pestalotiopsin A. Side Chain Installation and Exhaustive Probing of Olefin Metathesis as a Possible Tool for Elaborating the Cyclononene Ring

Cascade Rearrangements Following Twofold Addition of Alkenyl Anions to Squarate Esters

The four C s -symmetric cis[n.3.1] bicyclic ketones where n=3,5,7, and 9 were acetalized with (R,R)-2,4-pentanediol, and the resulting derivatives were cleaved with triisobutylaluminum (TRIBAL). The first three examples, all of which have their polymethylene chain rigidly fixed in a diaxial orientation, undergo ring opening with very high diastereoselectivity. In the fourth case (n=9), the chain is sufficiently long to be attached in a diequatorial manner

Asymmetric functionalization of conformationally distinctive Cs-symmetric cis-[n.3.1] bicyclic ketones. Definition of the absolute course of enantio- and diastereodifferentiation

Leo A. Paquette

Papers

Relevance of oxyanion stereochemistry to chirality transfer in anionic oxy-cope rearrangements

Electronic control of stereoselectivity. 1. Singlet oxygen and related electrophilic additions to aryl-substituted 7-isopropylidenebenzonorbornenes

Pestalotiopsin A. Side Chain Installation and Exhaustive Probing of Olefin Metathesis as a Possible Tool for Elaborating the Cyclononene Ring

Cascade Rearrangements Following Twofold Addition of Alkenyl Anions to Squarate Esters

Asymmetric functionalization of conformationally distinctive Cs-symmetric cis-[n.3.1] bicyclic ketones. Definition of the absolute course of enantio- and diastereodifferentiation