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.