Reaction #1126390

Reaction equation

triethylamine

1,4-phenylenediisocyanate

1-ethynyl-2-methoxy-benzene

6-nitro-hexanoic acid ethyl ester

→

orange oil

Yield 97.9%

5-[5-(2-Methoxy-phenyl)-isoxazol-3-yl]-pentanoic acid ethyl ester

Yield 97.9%

Solvents

toluene

Conditions

Workup

1. 1
   Temperatureto reflux under N2
2. 2
   Filtrationfilter mixture through a pad of Celite®
3. 3
   Washrinse with toluene
4. 4
   ConcentrationConcentrate

Procedure

Add 1,4-phenylenediisocyanate (14.5 g, 90.8 mmol) to a stirred solution of 1-ethynyl-2-methoxy-benzene (4.0 g, 30.3 mmol) and 6-nitro-hexanoic acid ethyl ester (8.6 g, 45.4 mmol) in toluene (300 mL, anhydrous) and stir under N2. Add triethylamine (12.7 mL, 90.8 mmol) and heat to reflux under N2. After 2.5 hours, filter mixture through a pad of Celite® and rinse with toluene. Concentrate to get 9 grams of a orange oil. Adsorb on SiO2 and purify the residue by flash chromatography on silica gel eluting with 0-20% EtOAc/hexanes to afford the title compound (14.0 g, 74%).

Source