The Synthesis of Triterpenes

Contracted porphyrins and calixpyrroles: synthetic challenges and ring-contraction effects

“…Tackling the total synthesis of natural products has led to the development of new synthetic methods. 109–112 Similarly, resolving the various challenges in the synthesis of non-natural contracted porphyrins and calixpyrroles has contributed to the discovery of not only new reactions but also functional chromophores, metal complexes, and supramolecules. Controlling the ring strain during macrocyclization is crucial to obtain contracted porphyrinoids with a macrocyclic ring size smaller than the marginal size of compounds obtained via Rothemund–Lindsey protocol.…”