A new synthesis of pyrocin (1) and relatedcompounds is described. The reaction of 2-benzoyl-4,4-dimethyl-2-buten-4-olide (5b) with 2-methyl-1-propenylmagnesium bromide (6) in the presence of CuCl gave α-benzoylpyrocin (7b) in 90% yield. The product of 7b with a specific rotation of +2.43° was obtained when the reaction was carried out in the presence of (−)-sparteine. α-Acetylpyrocin (7a) was prepared