Transition metal-free access to 3-indolemalononitriles via a tandem decarboxylative propargylation/aromatization cascade

Herein, the construction of 3-indolemalononitriles via base-promoted tandem decarboxylative propargylation/aromatization cascade of 4-ethynyl benzoxazinones with N,N-disubstituted aminomalononitriles has been developed. This protocol features mild reaction conditions, high efficiency and no need of transition metals. Various 3-indolemalononitriles can be obtained in moderate to excellent yields from readily available starting materials. More importantly, this method can be further applied to the synthesis of a wide range of complex indole products.