Synthesis of sphingosine relatives. Part 19.1 Synthesis of penaresidin A and B, azetidine alkaloids with actomyosin ATPase-activating properties

Three stereoisomers of penaresidin A 1 and two stereoisomers of penaresidin B 2′ (Scheme 5), azetidine alkaloids isolated from the Okinawan marine sponge Penares sp., have been synthesized. In the course of our synthetic study, the correct structure of penaresidin B has been shown to be not 2 but 2′. Natural penaresidin A is either (2S,3R,4S,15S,16S)- or (2S,3R,4S,15R,16R)-1 and natural penaresidin B is either (2S,3R,4S,15S)- or (2S,3R,4S,15R)-2′.