Reversing the normal mode of reactivity for a specific functional group has a number of strategic advantages in synthetic organic chemistry. Although acyl anion equivalents have featured widely for the construction of α-substituted carbonyls, the related homoenolate equivalents that represent<i> umpolung</i> Michael acceptors have been far less studied. This may be attributed to the fact that metal-homoenolate nucleophiles cannot be generated directly from the corresponding carbonyl derivative. As a result, most of the attention in this area has been directed towards the use of “masked” homoenolate equivalents, a strategy that has not been widely adopted because of their ambident reactivity, which thereby limits the efficiency and selectivity of this process. The presentation will describe the development of a highly enantioselective rhodium-catalyzed allylic alkylation of β,γ-unsaturated a-amino nitriles, which can be readily converted to a variety of β-stereogenic carbonyl derivatives. This transformation represents a rare example of the regio-, geometrical and enantioselective alkylation of an allylic anion, where the challenges associated with controlling each aspect of selectivity will be highlighted.

Stereoselective allylic alkylation of β,γ-unsaturated α-amino nitriles: Synthetic homoenolate equivalents

255th National Meeting (2018)

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