Total synthesis of (+)-phomopsolide C by ring-size selective ring-closing metathesis/cross-metathesis.

[reaction: see text]A new strategy for the synthesis of chiral 6-substituted 5,6-dihydro-5-hydroxypyran-2-ones by ring-size selective ring-closing metathesis (RCM) and its application to a short total synthesis of (+)-phomopsolide C are described. The key bond-forming reactions in this approach are a chemoselective cross-metathesis (CM) and RCM.