Overmann rearrangement

Since its discovery in 1974, more than 180 papers have been published on the use of the Overmann rearrangement to prepare allylic amines and their analogs from their allylic alcohols. For example, a recent synthesis of the fluoroalkene peptidomimetic precursor of A -acetyl-Z,-glutamyI-Z.-alanine involves the Overman rearrangement of the imidate derived from the allylic alcohol 60. ° This alcohol is readily prepared through Evans asymmetric aldol reaction of oxozolidinone with an aldehyde. 

A number of intramolecular acylations of vinylsilanes have been reported164,165 (equations 52 and 53). Trost has cyclised the thioketal 30 using dimethyl (methylthio)sulphonium fluoroborate which leads to the rearranged product 31166 (see equation 54). Overmann has used iminium salts to achieve both endocyclic and exo-cyclic ring closures167 - 169 (equations 55 and 56). In this latter case it is proposed that 32... 

Overmann and Knoll have shown that many non-strained acyclic 1,5-dienes undergo clean Cope rearrangement at room temperature on treatment with catalytic amounts of bis(benzonitrile)palladium(ii) chloride (c.g. Scheme 98). There are, however, structural limitations to the types of 1,5-diene that undergo rearrangement under the reaction conditions used, since some substrates give no trace of the Cope-rearranged isomers. 

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