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.