Reaction #42652

Reaction equation

t-butyl methyl ether hexane chloroform

(11β,16β)-9-fluoro-17-hydroxy-16-methyl-3,20-dioxo-11-[(trimethyl-silyl)oxy]-pregna-1,4-dien-21-yl acetate

ethyl isocyanate

→

title compound

Yield 62.5%

(11β,16β)-21-(acetyloxy)-9-fluoro-16-methyl-3,20-dioxo-11-[(trimethylsilyl)-oxy]pregna-1,4-dien-17-yl ethylcarbamate

Yield 62.5%

Solvents

toluene

Conditions

Workup

1. 1
   Temperaturethe mixture was refluxed for 48 hours
2. 2
   Otherevaporated under vacuum
3. 3
   Otherto leave a slightly gummy solid

Procedure

To a mixture of (11β,16β)-9-fluoro-17-hydroxy-16-methyl-3,20-dioxo-11-[(trimethyl-silyl)oxy]-pregna-1,4-dien-21-yl acetate (3.11 g, 6.15 mmol) in 41 mL of toluene was added neat ethyl isocyanate (20.5 mL, 259 mmol) and the mixture was refluxed for 48 hours. The resulting solution was cooled to room temperature and evaporated under vacuum to leave a slightly gummy solid. Flash chromatography through a 1 kg column of silica gel eluting with t-butyl methyl ether/hexane/chloroform (1:1:1) gave 2.22 g of the title compound as a white solid.

Source