Reaction #6397

Reaction equation

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

sec-butenyl trichloroacetimidate

Trifluoromethanesulfonic acid

→

title compounds

17-Ethyl-1,14-dihydroxy-12-[2'-(3"-sec-butenyloxy-4"-hydroxycyclohexyl)-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

Conditions

Workup

1. 1
   workup.ADDITIONto mix for 5 minutes
2. 2
   OtherAfter 15 minutes the reaction was quenched by the addition of saturated sodium bicarbonate
3. 3
   Extractionextracted with ethyl acetate (3×8 ml)
4. 4
   WashThe combined organics were washed with brine
5. 5
   Dryingdried over magnesium sulfate
6. 6
   OtherPurification of the
7. 7
   Concentrationconcentrate by preparative TLC on silica gel (ethyl acetate:hexane (1:1)+1% methanol)

Procedure

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 (150 mg in 3 ml 33% methylene chloride in cyclohexane), sec-butenyl trichloroacetimidate (62 μl neat) was added and the reagents allowed to mix for 5 minutes. Trifluoromethanesulfonic acid (2 μl neat) was added slowly via syringe and the mixture stirred at room temperature. After 15 minutes 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 (1:1)+1% methanol) gave the title compounds (11 mg 4"-ether; 13 mg 3"-ether).

Source