Cover Feature: Enantioselective Electrophilic Cyanation of Boron Enolates: Scope and Mechanistic Studies (Chem. Eur. J. 64/2018)

Abstract

The picture shows the unique six‐membered ring transition state of the umpolung reaction described in the Full Paper by K. Kiyokawa, M. Yamanaka, S. Minakata, et al. on page 17027. Enantioselective electrophilic cyanation with chiral boron enolates and p‐toluenesulfonyl cyanide (TsCN) has been achieved, providing an efficient access to acyclic chiral β‐ketonitriles with a high degree of enantioselectivity. The cyanation was found to proceed via the six‐membered ring transition state, in which TsCN is effectively activated by the coordination of its cyano group to the Lewis acidic boron center of the boron enolate. The reaction is figuratively represented by the motif of a vampire sucking the blood of a woman (who will then turn into a vampire).