Revised Structure of Pseudodistomin A, a Piperidine Alkaloid Isolated from the Okinawan Tunicate Pseudodistoma kanoko

Pseudodistomin A [1], a piperidine alkaloid isolated from the Okinawan tunicate Pseudodistoma kanoko was previously assigned with a 3'E,5'Z-diene in the side-chain; it is now shown to possess a 6'E,8'Z-diene. Ozonolysis of the triacetate of 1 afforded the same product as that obtained from the triacetate of the 6',8'-diene pseudodistomin B [2], indicating that the diene position of 1 is the same as that of 2.