Society is currently facing major challenges in providing resources such as healthcare in a more sustainable manner. The production of pharmaceuticals relies heavily on the use of precious transition metals such as palladium and rhodium to mediate single transformations on route to desired bioactive substances. Although these transformations are often high yielding, the need to mine great quantities of these metals remains a concern. Therefore, synthetic chemists must strive to develop more environmentally friendly and sustainable chemistry to access desirable and important scaffolds.

We report on the development of a novel route to tricyclic lactam products via a facile Aza-Diels-Alder reaction of catalytically generated N-acyliminium ions. Employing a Ca(NTf2)2 / nBu4NPF6 catalyst system in low loadings, to synthesise a diverse range of fused ring systems which differing electronic and steric properties in predominately good yields.