Reaction #168157

Reaction equation

4-{(S)-1-[(S)-6-(2-hydroxy-2-methyl-propyl)-2-oxo-6-phenyl-[1,3]oxazin-an-3-yl]-ethyl}-benzoic acid hydrazide

toluene-4-sulfonic acid monohydrate

1,1,1-trimethoxy-ethane

→

title compound

(S)-6-(2-Methyl-allyl)-3-{(S)-1-[4-(5-methyl-[1,3,4]oxadiazol-2-yl)-phenyl]-ethyl}-6-phenyl-[1,3]oxazinan-2-one

Solvents

ethyl acetate

Conditions

Workup

1. 1
   Temperaturefinally at reflux temperature for 1.5 h
2. 2
   TemperatureAfter cooling to ambient temperature
3. 3
   Washthe resulting mixture was washed with aqueous NaHCO3 solution and brine
4. 4
   OtherThe solvent was removed under reduced pressure
5. 5
   Otherthe residue was purified by chromatography on silica gel (CH2Cl2/MeOH 99:1→95:5)

Procedure

A mixture of 4-{(S)-1-[(S)-6-(2-hydroxy-2-methyl-propyl)-2-oxo-6-phenyl-[1,3]oxazin-an-3-yl]-ethyl}-benzoic acid hydrazide (90 mg), toluene-4-sulfonic acid monohydrate (10 mg), and 1,1,1-trimethoxy-ethane (1 ml) was stirred at room temperature for 1 h, at 80° C. for 2 h, and finally at reflux temperature for 1.5 h. After cooling to ambient temperature, ethyl acetate was added and the resulting mixture was washed with aqueous NaHCO3 solution and brine. The solvent was removed under reduced pressure and the residue was purified by chromatography on silica gel (CH2Cl2/MeOH 99:1→95:5) to afford the title compound as a colorless resin-like solid.

Source