BIOSYNTHESIS - PART 27 - COLCHICINE - STUDIES OF THE PHENOLIC OXIDATIVE COUPLING AND RING-EXPANSION PROCESSES BASED ON INCORPORATION OF MULTIPLY LABELED 1-PHENETHYLISOQUINOLINES
E. Mcdonald et al., BIOSYNTHESIS - PART 27 - COLCHICINE - STUDIES OF THE PHENOLIC OXIDATIVE COUPLING AND RING-EXPANSION PROCESSES BASED ON INCORPORATION OF MULTIPLY LABELED 1-PHENETHYLISOQUINOLINES, Journal of the Chemical Society. Perkin transactions. I (Print), (18), 1998, pp. 2979-2987
Earlier research from our group had proved that the biosynthesis of co
lchicine and its tropolonoid relatives involves the oxidative ring-clo
sure of a 1-phenethyltetrahydroisoquinoline, autumnaline, followed by
extensive modification of the cyclised product. These steps pose many
mechanistic and stereochemical questions which are set out in the Intr
oduction. The sequel then provides the answers based on the results fr
om a series of incorporation experiments on Colchicum plants involving
multiply labelled forms of autumnaline and its biological precursors.
These multiply labelled samples required the synthesis of eleven diff
erently labelled tetrahydroisoquinolines; the methods used to introduc
e the labels are described. Autumnaline is shown to be present in Colc
hicum autumnale plants and labelled forms of some precursors of it are
synthesised and studied. Taken together, the findings allow further d
efinition of a substantial part of the biosynthetic pathway to colchic
ine and its relatives.