Methanol → Hydroxycamptothecin

Participants

Reaction Steps

Naturally available mixture of 10 and 11-hydroxy camptothecin (1.0 g) is dissolved in anhydrous trifluoroacetic acid (5 ml) and anhydrous methanol (10 ml) to form a homogeneous solution of the quaternized components of the mixture. The homogeneous solution is then absorbed over enough silica gel (60 A; 60-230 mesh) to form a thick slurry. This slurry is dried by evaporating methanol and excess acid in vacuo on a rotary evaporator, leaving a powdery mass. The powder is then loaded over a pre-equilibrated silica gel column using chloroform. The column is washed using 1000 ml of a solvent mixture of 80% chloroform-20% methanol to remove non polar impurities, occluded trifluoroacetic acid and 11-hydroxcamptothecin (fraction A). Elution is then continued with chloroform-methanol-triethyl amine (in the approximate ratio of 1:1:0.01) and the band migrating away from the origin is collected using this eluent (Fraction B). Fractions A and B are evaporated separately and analyzed. Fraction B corresponds to the 10-hydroxy camptothecin isolate.

Provenance & Evidence