Stereoselective Total Synthesis of All ( <i>8E</i> )‐Stereoisomers of Panaxjapyne B

The first stereoselective total synthesis of all possible ( 8E )‐stereoisomers of panaxjapyne B was accomplished in a convergent fashion. The synthesis involves copper(I)‐mediated regioselective Grignard opening of ( R ) ‐ and ( S ) ‐ OTBS glycidyl ethers, base‐induced elimination of β‐alkoxy iodides followed by Cadiot–Chodkiewicz cross‐coupling reaction as the key steps. D‐(−)‐Diethyl tartrate and both ( R ) ‐ and ( S ) ‐ OTBS glycidyl ethers were used as chiral pool starting materials for the construction of the crucial chiral ene‐yne and chiral bromoalkyne fragments. Comparative analysis revealed that, out of all four possible ( 8E )‐stereoisomers of panaxjapyne B, three isomers correspond to natural products.