2-Amino-5-bromopyridine → 5-Bromo-2-(2,2,5,5-tetramethyl-1,2,5-azadisilolidin-1-yl)pyridine

Temperature

-78 °C

A solution of 2-amino-5-bromopyridine (5.00 g, 28.90 mmol) was dissolved in tetrahydrofuran (80 mL), cooled to −78° C., and then treated with a 2.5M solution of n-butyllithium in hexanes (11.68 mL, 29.20 mmol). The resulting reaction mixture was stirred for 1 h, at which time, a solution of 1,2-bis(chlorodimethylsilyl)ethane (6.22 g, 28.90 mmol) in tetrahydrofuran (15 mL) was added dropwise to the reaction. The reaction mixture was stirred for another 90 min at −78° C. and then was treated with another portion of a 2.5M solution of n-butyllithium in hexanes (11.68 mL, 29.20 mmol). The reaction was slowly warmed to 25° C. where it was stirred for 2 h. The reaction was then quenched by the addition of a saturated aqueous sodium chloride solution (50 mL) and then extracted with diethyl ether (2×200 mL). The combined organic layers were dried over magnesium sulfate, filtered, and concentrated in vacuo. Kugelrohr distillation at 125–135° C. at 0.5 mmHg afforded 5-bromo-2-(2,2,5,5-tetramethyl-[1,2,5]azadisilolidin-1-yl)-pyridine (5.38 g, 59%) as a white solid: mp 50.4–55.8° C.

1. customThe resulting reaction mixture
2. stirringThe reaction mixture was stirred for another 90 min at −78° C.
3. temperatureThe reaction was slowly warmed to 25° C. where it
4. stirringwas stirred for 2 h
5. customThe reaction was then quenched by the addition of a saturated aqueous sodium chloride solution (50 mL)
6. extractionextracted with diethyl ether (2×200 mL)
7. dry with materialThe combined organic layers were dried over magnesium sulfate
8. filtrationfiltered
9. concentrationconcentrated in vacuo
10. distillationKugelrohr distillation at 125–135° C. at 0.5 mmHg

ORD record

ord-17e23f5aef8d4c09a5c843ea74ab4111

Source dataset

uspto-grants-2006_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07132425B2