A convergent synthesis of (17R,5Z,8Z,11Z,14Z)-17-hydroxyeicosa-5,8,11,14-tetraenoic acid analogues and their tritiated derivatives

17(R)-OH-AA and 14,15-dehydro-17(R)-OH-AA were synthesized from a common tetraacetylenic precursor and their azide derivatives were obtained in moderate yields via the corresponding p-toluenesulfonates. Since the azido group remained stable during tritiation procedure on Lindlarʹs catalyst in benzene, both 14,15-dehydro-17(S)-N3-AA and 14,15-dehydro-17(R)-OH-AA constitute useful intermediates in the synthesis of radio-labelled 17(S)-N3-AA and 17(R)-OH-AA. In contrast, reduction of azide in methanol afforded 17(S)-NH2-AA with 95% yield.