Reserpine → Methyl (3beta,16beta,17alpha,18beta,20alpha)-18-hydroxy-11,17-dimethoxyyohimban-16-carboxylate

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Reaction Steps

A suspension of reserpine (1 g, 0.16 mmol) in a solution of sodium methoxide (0.150 g, 4.8 mmol) in methanol (50 ml) was refluxed until disappearance of the starting material (1 h), then cooled and concentrated under vacuum to one third of the volume. The solution was diluted with water (60 ml) and pH was adjusted to 1 with concentrated hydrochloric acid. The aqueous solution was then repeatedly washed with ethyl ether. The aqueous phase was then alkalinized with concentrated ammonia and repeatedly extracted with methylene chloride (4×30 ml). The combined organic phases were dried over sodium sulfate and concentrated under vacuum to give an amorphous residue (0.66 g), used for the following step without any further purification.

Provenance & Evidence