N.m.r. assignments of ring A hydrogens in gibberellin A4 methyl esters and some derivatives

Abstract

Full assignments of the ¹H n.m.r. chemical shifts of the ring A protons in gibberellin A₄, 3-epi-gibberellin A₄ and 3-oxogibberellin A₄ methyl esters have been made on the basis of ¹H and ²H n.m.r data of [2,2,6-²H₃]-, [1 β,3-²H₂]-, and [1 β,2,2,3,6-²H₅]-labelled derivatives These assignments have been used to determine the stereochemistry of the deuterium atoms in [1 β,2β-²H₂]gibberellin A₄ methyl ester, prepared via catalytic deuteriogenation of gibberellin A₇ 16,17-epoxide methyl ester.