Silver Mediated Banert Cascade with Carbon Nucleophiles.

The Banert cascade of propargylic azides can be promoted by simple silver salts, and the triazafulvene intermediate can be intercepted by carbon nucleophiles. Various indoles (>25 examples, up to 92% yield) and electron-rich heterocycles were effective. The Mayr nucleophilicity parameter () was found to correlate to the reaction efficiency, which enabled the formation of C-C and C-C bonds under otherwise identical conditions from structurally dissimilar nucleophiles.

Pd-Catalyzed Rearrangement of -Alloc--allyl Ynamides Auto-Tandem Catalysis: Evidence for Reversible C-N Activation and Pd(0)-Accelerated Ketenimine Aza-Claisen Rearrangement.

An auto-tandem catalytic double allylic rearrangement of -alloc--allyl ynamides was developed. This reaction proceeds through two separate and distinct catalytic cycles with both decarboxylative Pd-π-allyl and Pd(0)-promoted aza-Claisen rearrangements occurring. A detailed mechanistic study supported by computations highlights these two separate mechanisms.

Divergent Mechanisms of the Banert Cascade with Propargyl Azides.

Triazoles are privileged heterocycles for a variety of applications. The synthesis of 1-triazoles can be accomplished by the Banert cascade from propargylic azides. Depending on the substrate and conditions, the Banert cascade can proceed by either a sigmatropic or prototropic mechanism.

Kinetic Resolution of Cyclic Secondary Azides, Using an Enantioselective Copper-Catalyzed Azide-Alkyne Cycloaddition.

An enantioselective copper-catalyzed azide-alkyne cycloaddition (E-CuAAC) is reported by kinetic resolution. Chiral triazoles were isolated in high yield with limiting alkyne (up to 97:3 enantiomeric ratio (er)). A range of substrates were tolerated (>30 examples), and the reaction was scaled to >1 g.

Formation of Ketenimines via the Palladium-Catalyzed Decarboxylative π-Allylic Rearrangement of N-Alloc Ynamides.

A new approach for the formation of ketenimines via a decarboxylative allylic rearrangement pathway that does not require strong stabilizing or protecting groups has been developed. The products can be readily hydrolyzed into their corresponding secondary amides or reacted with sulfur ylides to perform an additional [2,3]-Wittig process. Mechanistic studies suggest an outer-sphere process in which reductive alkylation is rate-limiting.