Sulfuric Acid → Crotophorbolone

Participants

Reaction Conditions

Reaction Steps

To a 50 mL round-bottom flask containing a stirbar and phorbol (1.76 g, 4.82 mmol, 1.0 eq) at ambient temperature (23° C.) was added sulfuric acid (0.01 M aqueous H2SO4 solution: 16 mL, 0.3 M with respect to phorbol). The flask was equipped with a reflux condenser, the system flushed with a stream of dry nitrogen, and the cloudy, slightly yellow mixture heated to 90° C. After 1 h, the reaction vessel was cooled to room temperature (23° C.), the aqueous solution extracted with EtOAc, and the organic phase washed with brine. The organic phase was dried over Na2SO4, filtered, concentrated under reduced pressure, and purified by flash chromatography on a 4.5×18 cm silica gel column eluting with a solvent gradient from 75% to 90% EtOAc/petrol ether followed by elution with 100% EtOAc. The eluant was collected in 75 mL portions, and the crotophorbolone containing fractions were combined and concentrated to give crotophorbolone (654 mg).

Provenance & Evidence