The first total synthesis of the novel hepatotoxin (±)-cylindrospermopson (1) has been accomplished in 20 steps from 4-methoxy-3-methylpyridine (12) in 3.5% overall yield. The substituted piperidine A ring 19 was generated stereospecifically by a four-step sequence using the addition of trimethylsilylethynylmagnesium bromide to 12 to give 16 and stereospecific addition of vinylcuprate to 16 to form 17. The reaction of diamine 26 with ...