Synthesis of macrolactams

Vasudevan A, Verzal MK (2005) A post-Ugi carbonylation/intramolecular amidation approach toward the synthesis of macrolactams. Tetrahedron Lett 46 1697-1701... 

The synthesis of larger rings has also been accomplished including the fully unsaturated azolo-fused 1,3-diazepines (222) from bis(iminophosphoranes) (221) and novel cyclic carbodiimides (e.g. 223). Iminophosphoranes are also intermediates in the synthesis of macrolactams (e.g. 225) from the reaction of co-azido acid anhydrides (e.g. 224) with tributylphosphine. The synthesis of iminophosphorane-containing cryptands and a spherand-type structure have been reported. 

---