Synthesis of Oxepin- and Oxocin- Annulated Pyrimidine Derivatives by Claisen Rearrangement and Ring Closing Metathesis/Ring Closing Enyne Metathesis

A novel procedure is described for the formation of methyl and vinyl substituted oxacycle fuseduracil derivatives. Ring closing metathesis and enyne metathesis of dienes and enynes respectively proceeded smoothly under nitrogen atmosphere at room temperature in the presence of well defined catalyst (firstgeneration Grubbs’ catalyst) to afford the substituted oxepin derivatives in good yields. The substrates wereprepared by the Claisen rearrangement and subsequent alkylation of the rearranged products.