Macrocyclic lactones metathesis reactions

The preparation of macrocyclic lactones by metathesis coupling reactions is described (3). 

Meyers and co-workers" completed the first synthesis of (—)-griseoviridin 1184. In this case, the authors envisioned an unprecedented olefin metathesis reaction of 1269 would construct the macrocycle (Scheme 1.325). Amide bond disconnection of 1269 then led to the key intermediate fragments, an oxazole diene moiety 1270, and the sulfur-containing nine-membered ring lactone 1271. 

The industrial syntheses of exaltolide start in part likewise from cyclododeca-none. Key reactions are ring expansions and depolymerisation of the polyester of w-hydroxypentadecanoic acid. Of course, ring-closing metathesis also offers an attractive path to macrocyclic lactones. 

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