Triisopropyl borate → (2,3-Dimethylpyridin-4-YL)boronic acid

温度

-20 °C

A solution of 4-bromo-2,3-dimethyl-pyridine (1.38 g) and triisopropyl borate (2.05 mL) in 4 mL dry THF and 14 mL dry toluene was strirred on a dry ice-aceton bath to an internal temperature of −65° C. and 3.56 mL n-BuLi in hexanes was added dropwise over 0.5 h. Stirring continued at −65° C. for additional 2 h, then the bath was removed the mixture allowed to warm to −20° C. Reaction was quenched by addition of 10 mL 2M HCl, then allowed to warm to rt and diluted with more THF. 5M NaOH was added until the mixture reached pH 7, layers formed and the organic layer was collected. Several more extractions with THF were done and the combined organic extracts were dried with brine and Na2SO4 and concentrated under reduced pressure. The product crystallized and two crops were collected, for a total of 304 mg of 2,3-dimethylpyridine-4-boronic acid. LCMS (m/z) 153.

1. additionwas added dropwise over 0.5 h
2. customthe bath was removed the mixture
3. customReaction
4. customwas quenched by addition of 10 mL 2M HCl
5. temperatureto warm to rt
6. additiondiluted with more THF
7. addition5M NaOH was added until the mixture
8. customformed
9. customthe organic layer was collected
10. extractionSeveral more extractions with THF
11. dry with materialthe combined organic extracts were dried with brine and Na2SO4
12. concentrationconcentrated under reduced pressure
13. customThe product crystallized
14. customtwo crops were collected, for a total of 304 mg of 2,3-dimethylpyridine-4-boronic acid

ORDレコード

ord-7cc8654db2664420a8a00e2f7981d748

出典データセット

uspto-grants-2015_11

DOI

10.6084/m9.figshare.5104873.v1

特許番号

US09175003B2