Crude alkaloid extracts from the leaves of South American Erythroxylum coca var. coca were subjected to alumina chromatography and recrystallization to isolate fractions containing eleven previously unreported 2-carbomethoxy-3-oxo substituted tropane alkaloids. Specifically, the butyroyl-, 2-methylbutyroyl-, isovaleroyl-, senecioyl-, tigloyl-, trans-4-hexenoyl-, hexanoyl-, trans-3-hexenoyl-, trans-2-hexenoyl-, trans-3-heptenoyl- and trans-, trans-2,4-hexadienoyl-ecgonine methyl esters were characterized via electron and chemical ionization gas chromatographic-mass spectrometric analyses and comparison to synthesized standards. Three additional alkaloids similar to the aforementioned esters were also presumptively identified as heptadienoylecgonine methyl ester (geometry not determined) and cis-, trans- and trans-, cis-2,4-hexadienoylecgonine methyl ester.