Examination of nature's favorite molecules reveals a striking preference for making carbon-heteroatom bonds over carbon-carbon bonds-surely no surprise given that carbon dioxide is nature's starting material and that most reactions are performed in water. Nucleic acids, proteins, and polysaccharides are condensation polymers of small subunits stitched together by carbon-heteroatom bonds. Even the 35 or so building blocks from which these crucial molecules are made each contain, at most, six contiguous C-C bonds, except for the three aromatic amino acids. Taking our cue from nature's approach, we address here the development of a set of powerful, highly reliable, and selective reactions for the rapid synthesis of useful new compounds and combinatorial libraries through heteroatom links (C-X-C), an approach we call "click chemistry". Click chemistry is at once defined, enabled, and constrained by a handful of nearly perfect "spring-loaded" reactions. The stringent criteria for a process to earn click chemistry status are described along with examples of the molecular frameworks that are easily made using this spartan, but powerful, synthetic strategy.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/1521-3773%2820010601%2940%3A11%3C2004%3A%3AAID-ANIE2004%3E3.0.CO%3B2-5

Click Chemistry: Diverse Chemical Function from a Few Good Reactions.

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

Stereoselective organic reactions in water.

[*] Dr. S. Narayan, Dr. J. Muldoon, Prof. M. G. Finn, Prof. V. V. Fokin, Prof. H. C. Kolb, Prof. K. B. Sharpless Department of Chemistry and the Skaggs Institute of Chemical Biology The Scripps Research Institute 10550 North Torrey Pines Road La Jolla, CA 92037 (USA) Fax: (+ 1)619-554-6738 E-mail: sharples@scripps.edu [**] We thank Dr. Vladislav Litosh for carrying out preliminary work. Support from the National Institutes of Health, National Institute of General Medical Sciences (GM 28384), the National Science Foundation (CHE9985553), the Skaggs Institute for Chemical Biology, and the W. M. Keck Foundation is gratefully acknowledged. S.N. thanks the Skaggs Institute for a postdoctoral fellowship. We also thank Dr. Suresh Suri, Edwards Air Force Base, California, for a generous gift of quadricyclane. We urge our fellow chemists to float their problematic reactions on water and to send observations of success or failure to us at onwater@scripps.edu for public dissemination with attribution. Supporting information for this article is available on the WWW under http://www.angewandte.org or from the author. Angewandte Chemie

https://onlinelibrary.wiley.com/doi/pdf/10.1002/anie.200462883

“On Water”: Unique Reactivity of Organic Compounds in Aqueous Suspension

Betrachtet man die in der Natur am haufigsten vorkommenden Verbindungen, so fallt auf, dass die Bildung von Kohlenstoff-Heteroatom-Bindungen gegenuber der von Kohlenstoff-Kohlenstoff-Bindungen deutlich bevorzugt ist Da zum einen Kohlendioxid die Basisverbindung der Natur ist und andererseits das Medium naturlicher Reaktionen zumeist Wasser ist, uberrascht dies sicherlich nicht Nucleinsauren, Proteine und Polysaccharide sind polymere Kondensationsprodukte kleiner Untereinheiten, die durch Kohlenstoff-Heteroatom-Bindungen verknupft sind Sogar die etwa 35 Baueinheiten, aus denen diese essentiellen Verbindungen bestehen, enthalten nicht mehr als sechs aufeinander folgende C-C-Bindungen, sieht man einmal von den drei aromatischen Aminosauren ab Mit der Natur als Vorbild richteten wir unser Interesse auf die Entwicklung leistungsfahiger, gut funktionierender und selektiver Reaktionen fur die effiziente Synthese neuartiger nutzlicher Verbindungen sowie kombinatorischer Bibliotheken mittels Heteroatomverknupfungen (C-X-C) Diese Synthesestrategie nennen wir „Click-Chemie“ Click-Chemie ist durch eine Auswahl einiger weniger nahezu idealer Reaktionen charakterisiert, mit all ihren Grenzen und Moglichkeiten In diesem Beitrag werden zum einen die strengen Kriterien, die Reaktionen erfullen mussen, um die Bezeichnung „Click-Chemie“ zu verdienen, definiert, zum anderen werden Beispiele fur molekulare Strukturen gegeben, die mit dieser spartanischen, aber dennoch leistungsfahigen Synthesestrategie leicht hergestellt werden konnen

Click-Chemie: diverse chemische Funktionalität mit einer Handvoll guter Reaktionen

The mechanism of rearrangement of chorismic acid and related compounds

The Claisen Rearrangement. Response to Solvents and Substituents: The Case for Both Hydrophobic and Hydrogen Bond Acceleration in Water and for a Variable Transition State

Antiaromaticity of cyclopropenyl anions

A solvent rate effect equation which uses four physical properties of the solvent for parameters has been applied wiht good success to solvolysis reactions, solvent E t values, Claisen Rearrangements, Diels-Alder reactions, endo-exo ratios in Dields-Alder reactions, azo-Cope rearrangements, and enol-ketone equilibria of the dimedone and pyridone variety

A semitheoretical multiparameter approach to correlate solvent effects on reactions and equilibria

The relative values of secondary ..cap alpha.. deuterium kinetic isotopic effects at the terminal and central carbons of 1,5-dienes undergoing the 3,3-shifts vary as a function of substitution. With radical stabilizing groups on C/sub 3/, the transition state more resembles two weakly coupled allyl radicals. With radical stabilizing substituents at C/sub 2/ and C/sub 5/, the transition state more resembles cyclohexane-1,4-diyl. A thermochemical argument renders unlikely cyclohexane-1,4-diyl as an intermediate in the 3,3 shift of 1,5-hexadiene. Comparison of the KIEs at C/sub 4/ and C/sub 6/ in the rearrangement of 3-oxa-1,5-hexadiene (allyl vinyl ether to 4-pentenal) to appropriate equilibrium isotope effects reveals that the transition state comes early with more bond breaking than making. The transition state structures for many 3,3 shifts are discussed in terms of the relative stabilities of the two nonconcerted alternatives arising from either complete bond breaking or complete bond making. 50 references, 7 tables.

Joseph J. Gajewski

Papers

The mechanism of rearrangement of chorismic acid and related compounds

The Claisen Rearrangement. Response to Solvents and Substituents: The Case for Both Hydrophobic and Hydrogen Bond Acceleration in Water and for a Variable Transition State

Antiaromaticity of cyclopropenyl anions

A semitheoretical multiparameter approach to correlate solvent effects on reactions and equilibria

Variable transition state structure in 3,3-sigmatropic shifts from .alpha.-secondary deuterium isotope effects