Ingenol → (4S,5R,6R,18R)-4,5-dihydroxy-3,8,8,15,15,18-hexamethyl-7,9-dioxapentacyclo[11.5.1.01,5.06,11.014,16]nonadeca-2,11-dien-19-one

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Reaction Steps

Ingenol is reacted with p-toluenesulphonic acid hydrate and acetone to give ingenol-5,20-acetonide according to the procedure of Opferkuch et al. (1981). Ingenol-5,20-acetonide is converted to the ingenol 3-acylate by treatment with the appropriate acyl chloride and 4-(N,N-dimethylamino)pyridine or pyridine in toluene or benzene, or treatment with the appropriate acid, an alkylpyridinium salt and tributylamine in toluene then treatment with methanolic perchloric acid according to the procedure of Sorg et al. (1982). The ingenol 3-acylate could be converted to the 20-chloro-20-deoxyingenol 3-acylate 5-benzoate by the method of Example 15.

Provenance & Evidence