Hexane → 2-Chloro-6-(tributylstannyl)pyrazine

Temperature

0 °C

To a solution of nBuLi, 1.6 m in hexane (21.49 mL, 34.4 mmol) in THF (80 mL) at −50° C. was added 2,2,6,6-tetramethylpiperidine (5.80 mL, 34.4 mmol). The mixture was warmed to 0° C. and stirred for 20 min. The mixture was then cooled to −78° C. In another flask, 2-chloropyrazine (0.974 mL, 10.91 mmol) and tributyltin chloride (2.96 mL, 10.91 mmol) were dissolved in THF (50 mL) and cooled to −78° C. The cooled solution was transferred to lithium solution through cannula and the resulting orange mixture was slowly warmed up to −40° C. in 3 h, and was quenched with sat. HCl:EtOH:THF (1:4:5, 50 mL) and warmed to RT. The mixture was neutralized with sat. NaHCO3 and the volatiles were removed. The residue was diluted in H2O and extracted with DCM. The combined organic layers were dried, filtered and concentrated. The residue was purified with silica gel chromatography (eluting with 0-30% DCM in Hex) to give 2-chloro-6-(tributylstannyl)pyrazine (3.15 g, 7.81 mmol, 71.5%) as a clear oil. MS (ESI, pos. ion) m/z: 405 (M+1). 1H NMR (400 MHz, CDCl3) δ ppm 8.42 (1H, s), 8.38 (1H, s), 1.50-1.62 (6H, m), 1.27-1.41 (6H, m), 1.14-1.22 (6H, m), 0.89 (9H, t, J=7.3 Hz)

1. temperatureThe mixture was then cooled to −78° C
2. temperaturecooled to −78° C
3. temperaturethe resulting orange mixture was slowly warmed up to −40° C. in 3 h
4. customwas quenched with sat. HCl:EtOH:THF (1:4:5, 50 mL)
5. temperaturewarmed to RT
6. customthe volatiles were removed
7. additionThe residue was diluted in H2O
8. extractionextracted with DCM
9. customThe combined organic layers were dried
10. filtrationfiltered
11. concentrationconcentrated
12. customThe residue was purified with silica gel chromatography (eluting with 0-30% DCM in Hex)

ORD record

ord-dad8cc203a9c48d5a23a92dc53ae304f

Source dataset

uspto-grants-2016_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09321756B2