Reaction #502127

Reaction equation

(2S)-2-(6-methoxy(2-naphthyl))propanoic acid

tert-butyl N-(2-hydroxyethyl)carbamate

1,3-dicyclohexylcarbodiimide

→

title compound

Yield 82.4%

2-((tert-Butoxy)carbonylamino)ethyl(2S)-2-(6-methoxy(2-naphthyl))propanoate

Yield 82.4%

Solvents

CH2Cl2

Conditions

Workup

1. 1
   OtherThe byproduct, dicyclohexyl urea, was removed by filtration
2. 2
   ConcentrationThe filtrate was concentrated
3. 3
   workup.DISSOLUTIONdissolved in EtOAc (50 mL)
4. 4
   Temperaturecooled in a dry-ice bath
5. 5
   Otherto precipitate the remaining dicyclohexyl urea
6. 6
   Filtrationfiltered
7. 7
   ConcentrationThe filtrate was concentrated
8. 8
   workup.DISSOLUTIONdissolved in CH2Cl2 (15 mL)
9. 9
   Otherprecipitated
10. 10
    OtherThe solid was dried under vacuum

Procedure

A solution of (2S)-2-(6-methoxy(2-naphthyl))propanoic acid (naproxen, 7.60 g, 33.0 mmol), tert-butyl N-(2-hydroxyethyl)carbamate (5.30 g, 32.9 mmol), N,N-dimethylaminopyridine (DMAP, 0.35 g, 2.86 mmol) and 1,3-dicyclohexylcarbodiimide (6.80 g, 33.0 mmol) in CH2Cl2 (200 mL) was stirred at ambient temperature overnight. The byproduct, dicyclohexyl urea, was removed by filtration. The filtrate was concentrated, dissolved in EtOAc (50 mL) and then cooled in a dry-ice bath to precipitate the remaining dicyclohexyl urea and then filtered. The filtrate was concentrated, dissolved in CH2Cl2 (15 mL) and hexane (200 mL) and then stirred until the product precipitated. The solid was dried under vacuum to give the title compound (10.12 g, 82% yield). Mp 82-84° C. 1H NMR (300 MHz, CDCl3) δ 7.72-7.65 (m, 3H), 7.42-7.38 (m, 1H), 7.16-7.11 (m, 2H), 5.05 (br, 1H), 4.13 (t, J=5.3 Hz, 2H), 3.91 (s, 3H), 3.87 (q, J=7.1 Hz, 1H), 3.30 (br. q, 2H), 1.58 (d, J=7.1 Hz, 3H), 1.45 (s, 9H). 13C NMR (75 MHz, CDCl3) δ 174.4, 157.6, 155.6, 135.4, 133.6, 129.2, 128.8, 127.1, 126.0, 125.8, 119.0, 105.5, 79.3, 63.7, 55.2, 45.2, 39.5, 28.2, 18.3. Mass spectrum (API-TIS) m/z 374 (MH)+. Anal. calcd. for C21H27NO5: C, 67.54; H, 7.29; N, 3.75. Found: C, 67.43; H, 7.16; N, 3.66.

Source