21641-60-1 Ajmalan-16-carboxylic acid, 19,20-didehydro-1-demethyl-17-hydroxy-, methyl ester, (2epsilon,17S,19E)- Methyl 19,20-didehydro-1-demethyl-17-hydroxyajmalan-16-carboxylate (2epsilon,17S,19E)- Vincarine