Benzothiazines in synthesis: studies directed toward the synthesis of erogorgiaene.

The use of benzothiazenes for the formal total synthesis of erogorgiaene and stereoselective total syntheses of two diastereomers of this natural product is described. In particular, the stereochemical course of a radical cyclization anticipated to give the correct relative stereochemistry for the synthesis of erogorgiaene is discussed utilizing both experimental and computational data.