The stereochemistry of a rearrangement and fragmentation reaction of ring D of 13-hydroxygibberellins

Abstract

Treatment of methyl 16(R)- and 16(S)-16,17-dibromo-16,17-dihydrogibberellate with aqueous potassium carbonate at room temperature affords an 8,13-epigibberellin from the 16(R)-epimer whilst the 16(S)-epimer reacts much more slowly to give a 16-bromo-13,16,17-fused oxetane and a 16-bromo-13,16-secogibberellin, indicating the importance of the stereochemistry of the 16-substituent in determining the reaction pathway.