Ethyl chloroformate → Ethyl 4-methylpent-2-ynoate

Temperature

-78 °C

Under an Ar atmosphere, to a mixture of 3-Methylbutyne (1.5 g, 22.0 mmol) in THF (15 ml) was added a solution of 2.5 M n-BuLi in hexanes (9.68 ml, 24.2 mmol) at −78° C. over 15 min, then the mixture was stirred at −78° C. for 5 min, and at −5˜−10° C. for 30 min. Ethyl chloroformate (2.63 g, 24.2 mmol) was added drop wise at −78° C., then the mixture was stirred at 0° C. for 1 h. The reaction was quenched with saturated aqueous NH4Cl under ice cooling, and the whole was extracted with Et2O. The organic layer was washed with brine, dried over Na2SO4, and then concentrated. Purification by kugelrohr distillation (1˜3 mmHg 70˜80° C.) gave 2b (59%). 2b: colorless oil; 1H-NMR (CDCl3) δ 1.24 (6H, d, J=7.0 Hz), 1.31 (3H, t, J=7.2 Hz), 2.70 (1H, sep, J=7.0 Hz), 4.22 (2H, q, J=7.2 Hz).

1. waitat −5˜−10° C. for 30 min
2. stirringthe mixture was stirred at 0° C. for 1 h
3. customThe reaction was quenched with saturated aqueous NH4Cl under ice cooling
4. extractionthe whole was extracted with Et2O
5. washThe organic layer was washed with brine
6. dry with materialdried over Na2SO4
7. concentrationconcentrated
8. customPurification
9. distillationby kugelrohr distillation (1˜3 mmHg 70˜80° C.)

ORD record

ord-3ce70215db6c4cd2b178895027fc7a80

Source dataset

uspto-grants-2012_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08236987B2