Reformatsky rearrangements

Beckmann rearrangement, 3, 710 Pyran-4-carbaldehyde, 2,2-dimethyl-tetrahydro-Reformatsky reaction, 3, 732 4H-Pyran-4-carbaldehydes synthesis, 3, 760-761 Pyran-2-carbonitrile, 5,6-dihydro-reactions, 3, 732... 

Rearrangement of a,/B-epoxy ketones to ftdicarbonyl isomers, 307 Reductive alkylation, 97 Reductive cleavage of halo ethers, 264 Reductive degradation of 19-substitutional steroids, 277, 278 Reformatsky reaction, 139 Removal of the C-10 substituent in steroids. 272... 

Pinacol-pinacolone rearrangement Prileschajew epoxidation reaction Reformatsky reaction Reimer-Tiemann reaction Rosemnund reduction Sandmeyer reaction Schiemann reaction Schmidt reaction or rearrangement Schotten-Baumann reaction Skraup reaction Sommelet reaction. ... 

The Claisen rearrangement, discovered in 1912, has proven to be a powerful tool for the stereoselective generation of C—C bonds69. It is widely employed in complex multistep syntheses (see, for example, References 86-89) and has inspired many variations, including the Carroll (1940), Eschenmoser (1964), Johnson (1970), Ireland (1972) and Reformatsky-Claisen (1973) reactions69. 

Several standard type organic reactions were successfully investigated, e.g., Reformatsky (58), Hofmann and Curtius (55), Willgerodt (7), (19), Glaisen Condensation, Pinacol Rearrangement (42) and Darzens Reaction (21). 

The oldest reaction involving a rearrangement of an organozinc compound is probably the Reformatsky reaction54 55. It took one hundred years until its key step could be classified as a [3,3)-sigmatropic shift ( metallo-Claisen rearrangement) on the basis of computational studies (equation 51)56. 

In this section, the aliphatic Cope and Claisen rearrangements, as depicted in the transformation of I to 2 in Scheme 2, are discussed, as well as variations of the latter (i.e.. Johnson-Claisen, Ireland-Claisen, Reformatsky Claisen, F.schenmoser-Claisen. Ficini Claisen, and hetero-Claisen rearrangements). When X is oxygen, replacement of Cl and C2 with an aromatic ring... 

Reformatsky reaction.5 The Reformatsky reaction of y-bromocrotonic acid with aldehydes or ketones in THF gives rise to a mixture of branched and linear unsaturated hydroxy acids. The former are the kinetic products and, on equilibration, rearrange to the latter products. 

Reformatsky-typc" reaction into zinc enolates (2) by treatment with zinc dust in a refluxing aromatic hydrocarbon solvent These undergo Oaisen rearrangement to zinc carboxylates (3) of y,d-unsaturated acids. Yields are depressed by a-alkyl substitution of (1) thus (3) is obtained in 100% yield when R = = CHj and R = R = H. 

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