Diisopropylamine → Ethyl 1-benzyloxymethylcyclobutanecarboxylate

Temperature

0 °C

n-Butyl lithium solution (2.20 M in hexane, 23.2 ml, 51 mmol) was added via a syringe under nitrogen to a stirred solution of di-i-propylamine (5.13 g, 51 mmol) and HMPA (3.5 ml, 20 mmol) in THF (100 ml) at 0° C. The resulting mixture was stirred at 0° C. for 10 minutes, cooled to -78° C., added a solution of ethyl cyclobutanecarboxylate (5 g, 39 mmol) in THF (10 ml) via a dropping funnel. The resulting mixture was stirred at -78° C. for 0.5 hour, then warmed to 0° C. and stirred for 0.5 hour. The mixture was recooled to -78° C., treated with a solution of benzyl chloromethyl ether (6.58 g, 42 mmol) in THF (10 ml). The resulting mixture was stirred at -78° C. for 20 minutes, slowly warmed to room temperature and stirred for 1 hour. It was poured into cold water, extracted with diethyl ether. The ethereal extract was washed successively with diluted HCl, 5% NaHCO3, dried, filtered and evaporated to give a residue. This residue was purified by distillation to afford the desired product as a pale yellow oil: bp 102-3° C. (0.02 mm); NMR (CDCl3) δ=1.23 (3H, t, J=7 Hz), 1.6~2.6 (6H, m), 3.68 (2H, s), 4.15 (2H, q, J=7 Hz), 4.53 (2H, s), 7.30 (5H, s).

1. temperaturecooled to -78° C.
2. stirringThe resulting mixture was stirred at -78° C. for 0.5 hour
3. temperaturewarmed to 0° C.
4. stirringstirred for 0.5 hour
5. customwas recooled to -78° C.
6. stirringThe resulting mixture was stirred at -78° C. for 20 minutes
7. temperatureslowly warmed to room temperature
8. stirringstirred for 1 hour
9. extractionextracted with diethyl ether
10. extractionThe ethereal extract
11. washwas washed successively with diluted HCl, 5% NaHCO3
12. customdried
13. filtrationfiltered
14. customevaporated
15. customto give a residue
16. distillationThis residue was purified by distillation

ORD record

ord-257c34f8a6164824a4ab713110167603

Source dataset

uspto-grants-1991_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05049696