Copper catalysis azidation-cyclization

Alternatively, copper may activate the iodoalkyne via the formation of a Jt-complex intermediate (Scheme 7.13b, which then engages the azide, producing complex 54. Cyclization then proceeds via a now familiar vinylidene-like intermediate 55, to give iodotriazole 52. A similar transition state has been proposed to explain the involvement of di-copper intermediates in the CuAAC reaction [114, 115]. The distinctive feature of this pathway is that the C—I bond is never severed during the catalysis. 

New synthetic methods for benzodiazepine synthesis involving Ugi-type multicomponent/post-Ugi cyclization reactions continue to be of interest. Ugi reactions of indole-2-carboxaldehydes, isocyanides, amines, and 2-iodobenzoic acid derivatives led to intermediates which, with copper(I) catalysis, underwent intramolecular indole N-arylation to produce indolo-fused benzodiazepinones, such as 134 (13CC2894). 2-Azido-benzaldehyde, isocyanides, propargylamines, and nitrophenols underwent Ugi-type reaction, Smiles-type rearrangement, and intramolecular azide-alkyne cyclization to afford triazolo-fused benzodiazepinones such as 135... 

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