The total synthesis of (+)-ryanodol. Part III. Preparation of (+)-anhydroryanodol from a key pentacyclic intermediate

This paper reports several studies that were carried out to learn how to transform the dextrorotatory pentacyclic key intermediate 5into (+)-anhydroryanodol (6). This transformation requires 24 steps, and takes place via the following intermediates: 5 → 11 → 19 → 34 → 36 → 39 → 144 → 150 → 6. The preparation of the key pentacyclic intermediate 5is reported in Parts I and II of this series. Keywords: anhydroryanodol, ryanodol, diterpene, organic synthesis, strategy.