Total Synthesis and Determination of Absolute Configuration of Cryptorigidifoliol G.

The first asymmetric total synthesis of (1,5,7)-cryptorigidifoliol G and (1,5,7)-cryptorigidifoliol G of the proposed natural product was achieved. The key steps in the synthesis involved Keck-Maruoka allylation, our own developed protocol for the construction of the -2,6-disubstituted dihydropyran, iodolactonization, cross-metathesis, Prins cyclization, and -Wittig olefination reaction. A comparison of the NMR as well as analytical data and thorough analysis of the 2D NMR suggested that the absolute stereochemistry of the proposed natural product is (1,5,7)-cryptorigidifoliol G.