Total Synthesis of Tanshinone I

A novel total synthesis of tanshinone I (1) via the intermediate 3-hydroxy-8-methyl-1,4-phenanthrenedione (8) is described. The low overall yields and the use of expensive reagents in the synthesis process were minimized by the use of the Diels–Alder reaction to directly construct the 1,4-phenanthrenedione scaffold, providing tanshinone I (1) in only three steps.