Trifluoromethanesulfonic acid → 17-Ethyl-1,14-dihydroxy-12-[2'-(4"-hydroxy-3"-isopropyloxycyclohexyl)-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-1,14-dihydroxy-12-[2'-(3",4"-dihydroxycyclohexyl)-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 (616 mg in 12 ml 33% methylene chloride in cyclohexane), isopropyl trichloroacetimidate (244 μl neat) was added and the reagents allowed to mix for 5 minutes. Trifluoromethanesulfonic acid (4 μl neat) was added slowly via syringe and the mixture stirred at room temperature. After 22 hours the reaction was quenched by the addition of saturated sodium bicarbonate and extracted with ethyl acetate (3×8 ml). The combined organics were washed with brine and dried over magnesium sulfate. Purification of the concentrate by preparative TLC on silica gel (ethyl acetate: hexane (2:1)+1% methanol) gave the title compound (145 mg 3"-ether).

Provenance & Evidence