Five-membered rings, ring-closing metathesis strategy

Abell and co-workers applied their ring-closing metathesis strategy for the synthesis of P-amino acids constrained by five- and six-membered rings to synthesize a seven-membered ring p-amino acid for incorporation into P-peptide mimetics. Treatment of diene 244 with a 5 mol % of 4 in benzene provided the corresponding P-amino acid derivative 245 in 96% yield. 

Srikrishna and co-workers used ring-closing metathesis to synthesize HM-3 and HM-4, two aromatic sesquiterpenes with antioxidant and antibiotic activity. Treatment of a diastereomeric mixture of allyl alcohols 60 and 62 with 5 mol % of 3 in dichloromethane, followed by oxidation with PCC gave the corresponding enones 61 and 63 in 93 and 96% yield, respectively. These compounds were readily converted to the corresponding aromatic sesquiterpenes in just a few additional steps. Srikrishna and co-workers applied a similar strategy to the construction of the five-membered... 

---