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
for the synthesis of tetrahydropyrans. However, it has been known that stereochemical outcome of IOCC depends on the local structure of substrates and sometimes requires harsh reaction conditions and/or prolonged reaction times for selective formation of 2,6-cis-substituted tetrahydropyrans. These shortcomings limit the feasibility of IOCC in the context of complex natural product synthesis. In this