Synthesis of pachastrissamine (jaspine B) and its derivatives by the late-stage introduction of the C-2 alkyl side-chains using olefin cross metathesis

An improved divergent synthesis of the four diastereomers of pachastrissamine from Garnerʹs aldehyde has been reported. The common intermediate was synthesized by an indium-mediated acetoxyallylation reaction. The long alkyl side chain was introduced in the late stage of the synthesis using an olefin cross metathesis reaction. Biological evaluation of the chain modified analogs of the (2S,3S,4R)-isomer demonstrated that biological activity was highly dependent on the chain length.