Etoposide Imp. C (EP):(5R,5aR,8aR,9S)-9-[[4,6-O-[(R)-ethylidene]-a-d-glucopyranosyl]oxy]-5-(4-hydroxy-3,5-dimethoxyphenyl)-5,8,8a,9-tetrahydroisobenzofuro[5,6-f][1,3]benzodioxol-6(5aH)-one (a-etoposide).