Coupling of alkenes with amides mediated by low-valent titanium, the Kulinkovich-de Meijere reaction, yields amino-cyclopropanes. This reaction involves two sequential carbon-carbon bond-forming steps: addition of a titanium–alkene complex to the amide carbonyl to give A followed by ring fragmentation (B) and a second carbon-carbon bond formation yielding the cyclopropane. We have recently reported the use of Bredt's rule to shut down the ring opening of A, producing amino ketones on hydrolysis of the stable intermediate. Cha pioneered the use of imide substrates (X = carbonyl) that yield an intermediate A sufficiently stable to be intercepted, producing versatile amino ketone products instead of cyclopropanes, expanding the potential applications of this unique alkene–amide reactivity. We have found that this concept can be expanded to include sulfonimide substrates (X = R"SO2). This substrate is an effective generalizing solution to intercepting intermediate A but one that requires balancing the electron-withdrawing capacity of X to prevent formation of B, yet not turning the nitrogen into a leaving group. The structure-reactivity results will be discussed as well as applications of the amino-ketone products.

Amino ketones from alkenes & amides by electronic control of the Kulinkovich-de Meijere reaction

255th National Meeting (2018)

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