Diastereoselective Total Synthesis of the Euphorbia Diterpenoid Pepluanol A: A Reductive Annulation Approach.

A new titanium(III)-catalyzed reductive annulation constructed a series of diversely functionalized 1,5-diols in good to excellent yields with respect to a wide scope of vinyl epoxide-aldehyde substrates. Taken together with a Diels-Alder reaction and a substrate-controlled diastereoselective cyclopropanation as additional key steps, the synthetic utility of this novel method has been preliminarily explored by the first and concise total synthesis of the Euphorbia diterpenoid (+/-)-pepluanol A.