A ring-D functionalized nor-triterpenoid of the lupane series as a key intermediate in the formation of widespread hydrocarbon derivatives of higher plant origin in petroleum

The nor-triterpenoid, 24-nor,28-lupanoic acid, methyl ester 1a, present as the acid in an African crude oil, was isolated and identified using NMR. This compound represents a key intermediate in the formation of nor-lupane derivatives which are widespread petroleum markers indicative of terrestrial inputs.