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 (300 mg in 4.5 ml 33% methylene chloride in cyclohexane) isopropyl trichloroacetimidate (142 mg neat) was added and the reagents allowed to mix for 5 minutes. Trifluoromethanesulfonic acid (13.4 μl neat) was added slowly via syringe and the mixture stirred at room temperature. After 5 days the reaction was diluted with ethyl acetate and quenched with saturated sodium bicarbonate. The layers were separated, and the organic layer was washed with brine then dried over magnesium sulfate. Purification of the concentrate by preparative TLC on silica gel (ethyl acetate : hexane (1:1)+1% methanol) gave the title compound (42 mg). 1H NMR consistent with the desired structure.

Provenance & Evidence