Activation of α‐Diazocarbonyls by Organic Catalysts: Diazo Group Acting as a Strong N‐Terminal Electrophile

For the first time α‐diazocarbonyls have been used as highly active N‐terminal electrophiles in the presence of bicyclic amidine catalysts. The CN bond‐forming reactions of active methylene compounds as C nucleophiles with α‐diazocarbonyls as N‐terminal electrophiles proceed quickly under ambient conditions, in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), because of the formation of the reactive N‐terminal electrophilic intermediates. DBU activates both the active methylene and α‐diazocarbonyl. Importantly, this reaction is general for both active methylenes and α‐diazocarbonyls, and the activation mode will lead to new synthetic applications of α‐diazocarbonyls.