Trifluoromethanesulfonic acid → 17-Ethyl-1-hydroxy-14-(tert-butyldimethylsiloxy)-12-[2'-(4"-allyloxy-3"-methoxycyclohexyl)-1'-methylvinyl]-23,25-dimethoxy-13,19,21,27-tetramethyl-11,28-dioxa-4-azatricyclo[22.3.1.04,9]octacos-18-ene-2,3,10,16-tetraone

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Reaction Steps

To a solution of 17-ethyl-1-hydroxy-14-(tert -butyldimethylsiloxy)-12-[2'-(4"-hydroxy-3"-methoxy -cyclohexyl)-1'-methylvinyl]-23,25-dimethoxy-13,19,21,27-tetramethyl-11,28-dioxa-4-azatricyclo[22.3.1.04,9]-octacos-18-ene-2,3,10,16-tetraone (2.1 g) (STEP 11B) in 24 ml 33% methylene chloride in cyclohexane, was added allyl trichloroacetimidate (938 mg neat) and the reaction mixture was allowed to mix for 5 minutes. Trifluoromethanesulfonic acid (41 μl neat) was added slowly via syringe and the mixture stirred at room temperature. After 24 hours, the reaction mixture was diluted with ethyl acetate and washed with saturated sodium bicarbonate, water and brine. The organic layer was dried over magnesium sulfate. Purification of the concentrate by flash chromatography on silica gel (ethyl acetate: hexane (1:5))+1% methanol) gave the title compound (1.03 g). 1H NMR consistent with the desired structure.

Provenance & Evidence