Enantioselective synthesis of cis-7-methoxy-calamenene via Claisen rearrangement of an enzymatically resolved allyl alcohol

An enantioselective synthesis of cis -7-methoxy-calamenene 1 has been accomplished through the following key-steps: (i) enzymatic resolution of the racemic allyl alcohol 3 to furnish the ( R )-enantiomer (ee >99%); (ii) Claisen-orthoester rearrangement of 4 to introduce the isopropyl unit on the benzylic position (99% ee); (iii) diastereoselective reduction of dihydronaphthalene derivative 11 to give the cis -isomer 12 (98% de); (iv) regioselective introduction of the formyl group by a Vilsmeier reaction followed by reduction to give 1 .