Reaction #1395

Reaction equation

sodium hydroxide

(R)-tert-leucinol

water

chloroformic acid ethyl ester

→

(R)-4-tert-butyl-2-oxazolidinone

Yield 80.0%

Solvents

toluene

Conditions

Workup

1. 1
   TemperatureThe mixture was then heated to 60°-65° C. at pH 8.0
2. 2
   Otherthe aqueous phase separated
3. 3
   Temperatureslowly heated
4. 4
   workup.ADDITIONafter the addition of 0.4 g finely granulated sodium hydroxide at 70° C
5. 5
   Otherproduced during the reaction
6. 6
   Otherwas separated from 70°-100° C
7. 7
   workup.ADDITIONwas added
8. 8
   Otherthe aqueous phase separated
9. 9
   Temperaturewarm water which
10. 10
    Otherwas separated again after a brief agitation at 65° C
11. 11
    workup.DISTILLATIONAfter distilling the organic phase on a water separator the phase
12. 12
    Concentrationwas concentrated to 120 ml
13. 13
    Filtrationfiltered hot
14. 14
    Temperatureslowly cooled off under agitation, during which the product
15. 15
    Otherseparated in colorless crystals
16. 16
    FiltrationThese crystals were filtered off after 30 min agitation at 5° C.
17. 17
    Washwashed with cold toluene
18. 18
    Otherdried in a vacuum at 50° C

Procedure

73 g (containing 0.25 mole (R)-tert-leucinol) of the filtrate cited in example 6 was taken up with 27 ml water and 200 ml toluene. 25 ml (0.26 mole) chloroformic acid ethyl ester were then added dropwise at 20°-25° C., during which the pH was maintained at 7-8.5 by the addition of 10 M sodium hydroxide solution. The mixture was then heated to 60°-65° C. at pH 8.0 and the aqueous phase separated. The toluene phase was dehydrated on a water separator under a slight vacuum and slowly heated after the addition of 0.4 g finely granulated sodium hydroxide at 70° C. A total of 40 ml distillate which contained the ethanol produced during the reaction was separated from 70°-100° C . After cooling of the batch to 65° C. a solution of 0.6 ml glacial acetic acid in 10 ml water was added, the mixture briefly agitated, the aqueous phase separated and the toluene phase compounded again with 15 ml warm water which was separated again after a brief agitation at 65° C. After distilling the organic phase on a water separator the phase was concentrated to 120 ml, filtered hot and slowly cooled off under agitation, during which the product separated in colorless crystals. These crystals were filtered off after 30 min agitation at 5° C., washed with cold toluene and dried in a vacuum at 50° C. 28.6 g (R)-4-tert-butyl-2-oxazolidinone (80% yield) was obtained. A 1H-NMR spectrum corroborated the structure of the product.

Source