Pyrrolizidine alkaloid biosynthesis; incorporation of 2H-labelled putrescines into retrorsine
Abstract
The labelling patterns in retrorsine (1) derived biosynthetically from [1,4-2H4]- and [2,3,-2H4]-putrescine have been established by 2H n.m.r. spectroscopy; in the former case the formation of (9S)-[9-2H]retrorsine (12) is consistent with stereospecific addition of hydrogen to the re-face of an aldehyde precursor (RC2HO).