Taxine. Part V. The structure of taxicin-II

Abstract

O-Cinnamoyltaxicin-II triacetate is converted by Zemplén methanolysis into the 2-monoacetate 5-cinnamate, whereas on similar treatment the series-I cinnamate triacetate suffers complete deacetylation, owing to the effect of its neighbouring 1-hydroxyl group. Cleavage of taxicin-II 2-monoacetate 5-phenylpropionate with periodate gives a 9,10-seco-dialdehyde. By means similar to those used with the corresponding series-I triacetate, O-cinnamoyltaxicin-II triacetate has been converted into a 4,16-dihydrotaxicin-II derivative, an oxonortaxicin-II tetra-acetate, and also a 9-oxo-derivative. Evidence obtained from these transformations, together with a comparison of the n.m.r. data for corresponding derivatives, shows that taxicin-II is the 1-deoxy-derivative of taxicin-I; this defines the gross structure of O-cinnamoyltaxicin-II triacetate.