The absolute stereochemistry of piptoside and dihydropiptosidin

Abstract

The absolute stereochemistry of piptoside and dihydropiptosidin has been determined at C5, C6 and C7 by comparison of dihydropiptosidin and leucodrin by means of molecular-rotation changes and p.m.r. spectroscopy, and by application of Horeau's method. Examination of p.m.r. parameters of some piptoside derivatives allows a tentative formulation at C4 and, together with previous results, allows the absolute stereochemistry of piptoside to be written as 2S,3S,4S,5S,6R,7S.