Transition-metal free cyano 1,3 migration of unsaturated cyanohydrins†
A novel approach of transition-metal-free cyano 1,3-migration of β,γ- and α,β-unsaturated cyanohydrins is reported. This method provides reliable and convenient access to β-cyano ketones in high yields. Furthermore, it has broad substrate scope and good functional group tolerance and could be scaled-up. Mechanistic study revealed that DBU plays three roles in this system, serving as a base as well as catalyzing hydride transfer and the addition of the cyano moiety to the unsaturated ketone intermediate.