Template Synthesis of a Huge Macrocycle by Olefin Metathesis Using Easily Accessible [Pt(PEt3)2] Templates

We have reported the template synthesis of a 90‐membered macrocycle by olefin metathesis. The macrocycle 7 was prepared by an initial six‐oxidative‐addition reaction of 2 by [Pt(PEt3)4]. The definite structure of a six‐oxidative product was confirmed by the crystal structure. The coordination of 2,6‐bis(hex‐5‐enyloxy)pyridine to 3 led to the hexacationic aryl complex of type 4. The metathesis of olefin‐substituted pyridine with Grubbs catalyst ([PhCHRuCl2(Cy3P)2]) formed the expected macrocycle 5. The olefin metathesis reaction was formed under high dilution to suppress intermolecular olefin metathesis polymerization. The detachment of the newly formed macrocycle 6, followed by reduction to alkane macrocycle 7 by using palladium on charcoal and hydrogen led to a huge macrocycle. The mild and easy access of the template protocol opens a host of potential subsequent transformations toward the construction of a variety of macrocycles. Think big! The macrocycle was synthesized by a six‐oxidative‐addition reaction of an iodohexaphenylbenzene derivative by using [Pt(PEt3)4], coordination of 2,6‐bis(hex‐5‐enyloxy)pyridine, metathesis of olefin‐substituted pyridine (see figure), and the detachment of a newly formed macrocycle, followed by reduction to the desired alkane macrocycle by using palladium on charcoal and hydrogen.