Tandem catalysis in domino olefin cross-metathesis/intramolecular oxa-conjugate cyclization: concise synthesis of 2,6-cis-substituted tetrahydropyran derivatives
diastereoselectivity (“auto-tandem catalysis”). In addition, we have found that the domino CM/IOCC of δ-hydroxy olefins with α,β-unsaturatedcarbonylcompounds could be achieved simply by performing CM in the presence of a Brønsted acid in CH2Cl2 at 25–35 °C, which delivered 2,6-cis-substituted tetrahydropyrans in good yields with excellent diastereoselectivity (“orthogonal-tandem catalysis”). To understand the