Double Duty for Cyanogen Bromide in a Cascade Synthesis of Cyanoepoxides

An unprecedented reaction mode of cyanogen bromide has been discovered. Under basic conditions, cyanogen bromide acts as an equivalent of both Br+ and CN− to convert enolizable ketones into the corresponding cyanoepoxides in good yields. This unique reaction mode provides new, one-pot access to densely substituted cyanoepoxides from easily available ketones (see scheme).