Establishment of the absolute configuration of the bioactive marine alkaloid eudistomin X by stereospecific synthesis

The marine β-carboline alkaloid eudistomin X has been synthesised stereospecifically, using d-phenylalanine as the chiral pool starting material, establishing the absolute configuration of the natural product as (10R). A stereospecific synthesis of both enantiomers of the marine alkaloid eudistomin X using the amino acid chiral pool is achieved. Comparison of 1H and 13C NMR chemical shifts of the synthetic product as either the free base, mono-salt or disalt with those reported for the natural product established that the ascidian metabolite was originally characterised as a mono-salt and that the absolute configuration was (10R).