Eschenmoser-Tanabe fragmentation

Fragmentation of a,P-epoxyketones via the intermediacy of a,P-epoxy sulfonyl-hydrazones. 

Eschenmoser, A. Felix, D. Ohloff, G. Helv. Chim. Acta 1967, 50, 708. Albert Eschenmoser (Switzerland, 1925-) is best known for his work on, among many others, the monumental total synthesis of Vitamin B12 with R. B. Woodward in 1973. He now holds appointments at ETH Zurich and Scripps Research Institute, La Jolla. 

Muller, R. K. Horn, U. loos, R. Schreiber, J. Eschenmoser, A. Helv. Chim. Acta 1972, 55, 1276. 

Name Reactions, 4th ed., DOI 10.1007/978-3-642-01053-8 90, Springer-Verlag Berlin Heidelberg 2009 

Kohout, L. Filip, J. Collect. Czech. Chem. Common. 1985, 50, 1402. 

R = tosyl, 2,4-dinitrophenyl R = H, alkyl when R = H, then the product is an alkynal, and when R = alkyl, then it is an alkynone 

Katzenellenbogen et al. developed an efficient method for the synthesis of alkyl-substituted enol lactones that are potent inhibitors of the serine protease elastase. The precursors for the enol lactones were a- and 3-alkyl-substituted 5-hexynoic acids, which were prepared by the bromoform reaction of the corresponding alkynoic methyl 

During modei studies for the synthesis of botrydiane sesquiterpene antibiotics, B.M. Trost and co-workers prepared a compiex 1,6-enyne precursor for transition metal catalyzed enyne metathesis reactions. The 1,6-enyne was prepared from a heavily substituted alkynal, which was synthesized via the Eschenmoser-Tanabe fragmentation of an epoxy ketone. The resulting alkynal was unstable, so it was immediately subjected to a Wittig oiefination to afford the desired 1,6-enyne. 

In the laboratory of S.J. Danishefsky, the synthesis of antibiotics containing the benz[a]anthracene core structure was 

Name Reactions A Collection of Detailed Mechanisms and Synthetic Applications, DOI 10.1007/978-3-319-03979-4 97, Springer International Publishing Switzerland 2014 

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Eschenmoser Fragmentation (Eschenmoser-Tanabe Fragmentation / Ring Cleavage)... 

Eschenmoser-Tanabe fragmentation Formation of alkynals or alkynones from epoxy ketone hydrazones. 158... 

Related reactions Eschenmoser-Tanabe fragmentation, Wharton fragmentation ... 

Crabbe and Greene employed a similar approach in their synthesis of a Corey intermediate. The synthesis, depicted in Scheme 1.33, began by construction of cuprate 166 via a slightly different route. 3-Methyl cyclohexenone (180) was epoxidized and subjected to Eschenmoser-Tanabe fragmentation to give the acetylenic ketone 181. Reduction of ketone 181 to the alcohol and protection afforded 164, which had been previously converted to cuprate 166 by Corey. 

Erdmann (see Volhard-Erdmann Cyclization) Erlenmeyer-Plochl Azlactone and Amino Acid Synthesis Eschenmoser Coupling Reaction Eschenmoser Fragmentation Eschenmoser-Claisen Rearrangement Eschenmoser-Tanabe Fragmentation Eschweiler-Clarke Reaction Etard Reaction... 

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