Structure assignment of aminoconduritols by ¹⁵N NMR correlation spectroscopy; synthesis of a positional isomer of 7-deoxypancratistatin

A positional isomer of 7-deoxypancratistatin was synthesized in 12 steps from epoxyaziridines 4 and 5. An intermolecular opening of the aziridine rather than the epoxide in the early stages of the synthesis led to 13, which did not match the properties of tetraacetate 10 derived from 7-deoxypancratistatin. At no stage of the synthesis did standard NMR techniques, involving ¹H-¹H or ¹H-¹³C coupling, prove adequate for the structure assignment. Unambiguous structure was assigned by ¹H-¹⁵N correlation NMR spectroscopy as well as by the conversion of epoxide 11 to diol 29 synthesized independently by another route. Experimental and spectral details are reported for all new compounds.