Unusual O-conjugate addition reactions of β-ketoesters and 1,3-diketones to ethyl propynoate: applications to the synthesis of furans

Divinyl ethers were synthesized from 1,3-dicarbonyl compounds. Reactions of β-ketoesters and 1,3-diketones with ethyl propynoate in the presence of N-methylmorpholine produced unusual O-conjugate addition products in good yields. The divinyl ethers derived from 1,3-diketones were utilized for the synthesis of 2,3,5-trisubstituted furans under the standard radical cyclization conditions.