Triethylamine → [(4-Methoxyphenyl)hydrazono]acetic acid ethyl ester

Temperature

2.5 °C

A suspension of 4-methoxy-phenylhydrazine hydrochloride (32, 14.0 g, 80.2 mmol) in anhydrous THF (100 mL) was treated with triethylamine (TEA, 8.10 g, 11.2 mL, 80.2 mmol, 1.0 equiv) before a solution of ethylglycolate (50% solution in toluene, 16.4 g, 80.2 mmol, 1.0 equiv) in toluene was dropwise added into the reaction mixture at 0-5° C. under N2. The resulting reaction mixture was then stirred at 0-5° C. for 30 min before being gradually warmed to 25° C. for 12 h. When TLC and HPLC showed the reaction was deemed complete, the reaction mixture was filtered to collect triethylamine hydrochloride salt. The filtrates were concentrated in vacuo, and the resulting solids were collected by filtration. The crude solids were washed with water (2×50 mL) and 20% of EtOAc/hexane (2×50 mL), and dried at 40-45° C. in vacuo for 12 h to afford the crude, desired [(4-methoxyphenyl)hydrazono]acetic acid ethyl ester (33, 16.0 g, 17.80 g theoretical, 90%), which was found to be pure enough to do the following reaction without further purification. For 33: CIMS m/z 221 (M+−H, C11H14N2O3).

1. additionwas dropwise added into the reaction mixture at 0-5° C. under N2
2. customThe resulting reaction mixture
3. temperaturebefore being gradually warmed to 25° C. for 12 h
4. filtrationthe reaction mixture was filtered
5. customto collect triethylamine hydrochloride salt
6. concentrationThe filtrates were concentrated in vacuo
7. filtrationthe resulting solids were collected by filtration
8. washThe crude solids were washed with water (2×50 mL) and 20% of EtOAc/hexane (2×50 mL)
9. customdried at 40-45° C. in vacuo for 12 h

ORD record

ord-b23ad070141443c09f1b914aa61cd286

Source dataset

uspto-grants-2005_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06919451B2