Reaction #1126395

Reaction equation

triethylamine

1,4-phenylenediisocyanate

4-chloro-2-ethynyl-1-methoxy-benzene

6-nitro-hexanoic acid ethyl ester

→

orange oil

Yield 64.5%

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

Yield 64.5%

Solvents

toluene

Conditions

Workup

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

Procedure

Add 1,4-phenylenediisocyanate (8.41 g, 52.5 mmol) to a stirred solution of 4-chloro-2-ethynyl-1-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 at room temperature under N2. Add triethylamine (7.3 mL, 52.5 mmol) and heat to reflux under N2 overnight. Filter mixture through a pad of Celite® and rinse with toluene. Concentrate to get 6.6 g of a orange oil. Adsorb on SiO2 and purify the residue by flash chromatography on silica gel eluting with 0-40% EtOAc/hexanes to afford the title compound (4.51 g, 76%). MS (IS) 338 (M+1)+.

Source