Acetone → 10aH-2,12a-Methano-1H,4H-cyclopropa(5,6)(1,3)dioxolo(2',3')cyclopenta(1',2':9,10)cyclodeca(1,2-d)(1,3)dioxin-15-one, 1a,2,7a,13,14,14a-hexahydro-1,1,6,6,9,9,11,13-octamethyl-, (1aR-(1aalpha,2alpha,7aalpha,7bR*,10aalpha,12aalpha,13alpha,14aalpha))-

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Reaction Steps

Ingenol can be converted to ingenol-3,4-acetonide by treatment with 4-toluenesulphonic acid hydrate and acetone to give ingenol-3,4:5,20-diacetonide followed by treatment with perchloric acid in methanol or zinc bromide in dichloromethane and methanol according to the method of Opferkuch et al. (1981). Ingenol-3,4-acetonide could be converted to ingenol-3,4-acetonide-20-trityl ether by treatment with trityl chloride and 4-(N,N-dimethylamino)pyridine in dry pyridine, acylated in an analogous manner to that described in Example 1 or Example 3 to give the ingenol-3,4-acetonide-20-trityl ether 5-acylate then treated with methanolic perchloric acid according to the method of Example 15 or Example 18 to give the ingenol 5-acylate. The ingenol 5-acylate could then be converted to the ingenol-3,4-acetonide 5-acylate by treatment with 4-toluenesulphonic acid hydrate and acetone according to the method of Opferkuch et al. (1981). The ingenol-3,4-acetonide 5-acylate could be converted to the 20-chloro-20-deoxy-3,4-acetonide 5-acylate by the method of Example 15.

Provenance & Evidence