2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane → 4,4,5,5-Tetramethyl-2-(3-methylbut-1-yn-1-yl)-1,3,2-dioxaborolane

Temperature

-78 °C

To a stirred solution of Ia (7.0 g, 50 mmol) in dry THF (25 mL) at −78° C. was added n-BuLi (1.6 M in n-hexane, 62.5 mL, 100 mmol). After being stirred for 1 hour at −78° C., the reaction mixture was warmed to room temperature and stirred for 1 hour at that temperature. Another flask was charged with 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7.8 mL, 38 mmol) in dry THF (50 mL) under argon atmosphere, and the reaction mixture was cooled to −78° C. The lithium acetylide from the first flask, which was cooled to −78° C., was slowly added to the second by a double-ended needle. The mixture was stirred at −78° C. for 2 hours, after which anhydrous HCI (100 mmol) was added. Then, reaction mixture was warmed to room temperature. After removal of the precipitated LiCI by filtration and removal of solvents under reduced pressure, the residue was purified by distillation (113-115° C./7 mbar) to afford IIIa (5.9 g, 80%) as an oil.

1. temperaturethe reaction mixture was warmed to room temperature
2. stirringstirred for 1 hour at that temperature
3. temperaturethe reaction mixture was cooled to −78° C
4. additionwas slowly added to the second by a double-ended needle
5. stirringThe mixture was stirred at −78° C. for 2 hours
6. additionafter which anhydrous HCI (100 mmol) was added
7. customThen, reaction mixture
8. temperaturewas warmed to room temperature
9. customAfter removal of the precipitated LiCI
10. filtrationby filtration and removal of solvents under reduced pressure
11. distillationthe residue was purified by distillation (113-115° C./7 mbar)
12. customto afford IIIa (5.9 g, 80%) as an oil

ORD record

ord-45d08b0ac5744ab2b3a02dcba8976658

Source dataset

uspto-grants-2014_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08785674B2