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.

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

Claisen rearrangement over the past nine decades.

Recent developments in the stereoselective synthesis of α-aminoacids

(1990). The Shikimate Pathway — A Metabolic Tree with Many Branche. Critical Reviews in Biochemistry and Molecular Biology: Vol. 25, No. 5, pp. 307-384.

The shikimate pathway―a metabolic tree with many branches

Treatment of the hydroxy lactone derived from (±)-endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carboxylic acid with hydrogen bromide–acetic acid, followed by esterification, gave 48% of ethyl DL-(1,3,5/2,4)-5-bromo-2,3,4-trihydroxy-1-cyclohexanecarboxylate, from which DL-validamine and pseudo-2-amino-2-deoxy-α-DL-mannopyranose, and their uronate analogs have been synthesized as the totally acetylated derivatives.

New Synthesis of Penta-N,O-acetyl-DL-validamine and Pseudo-2-amino-2-deoxy-α-DL-mannopyranose, and Their Uronate Analogs

Claisen rearrangement of (Z)-3-deoxy-3-C-[(hydroxymethyl)methylene]-1,2:5,6-di-O-isopropylidene-.alpha.-D-ribo-hexofuranose with triethyl orthopropionate

All the predicted isomers of 1,2 : 3,4- and 1,2 : 4,5-dianhydrocyclohexanehexols (5 racemates and 6 mesocompounds) were synthesized from appropriate inositol ditosylates and dimesylate by treatment with sodium methoxide.

Inositol Derivatives. 11. Synthesis of Dianhydroinositols

Diastereoselective acylation of the 2,3-O-cyclohexanediyl derivatives of (1,4/2,3,5)- and (1,2,3,4,5/0)-5-acetamidocyclopentane-1,2,3,4-tetraols with some optically active chiral acids afforded, with moderate diastereoselectivity, the chiral monoesters useful as synthetic intermediates, from which mannostatin A and its enantiomer were synthesized.

Preparation of optically active derivatives of (1,4/2,3,5)- and (1,2,3,4,5/0)-5-aminocyclopentane-1,2,3,4-tetraols: synthesis of mannostatin A and its enantiomer

The total synthesis of an antifungal novel amino acid derivative, sphingofungin D (N-acetyl asperfungin) starting from myo-inositol and (R)-epoxyoctane is described. This synthetic study showed that the undetermined stereochemistry at C-14 in sphingofungins should be R.

Seiichiro Ogawa

Papers

New Synthesis of Penta-N,O-acetyl-DL-validamine and Pseudo-2-amino-2-deoxy-α-DL-mannopyranose, and Their Uronate Analogs

Claisen rearrangement of (Z)-3-deoxy-3-C-[(hydroxymethyl)methylene]-1,2:5,6-di-O-isopropylidene-.alpha.-D-ribo-hexofuranose with triethyl orthopropionate

Inositol Derivatives. 11. Synthesis of Dianhydroinositols

Preparation of optically active derivatives of (1,4/2,3,5)- and (1,2,3,4,5/0)-5-aminocyclopentane-1,2,3,4-tetraols: synthesis of mannostatin A and its enantiomer

Total Synthesis and Absolute Configuration of Sphingofungin D (N-Acetyl Asperfungin)