Triethyl borate → (6-methoxy-2,3-dihydro-1H-inden-5-yl)boronic acid

Temperature

-78 °C

A dry 250 mL round bottom flask was charged with 6-bromo-2,3-dihydro-1H-inden-5-yl methyl ether (9.38 grams, 41.27 mmol) and placed under high vacuum for 18 hours. THF (51.6 mL) was added via syringe. The solution was homogeneous and clear. The reaction was cooled with a dry ice/acetone bath for 15 minutes, then n-BuLi was added semi-dropwise. A color change to pale yellow was observed. The reaction was stirred at −78° C. for 1 hour, followed by drop-wise addition of triethylborate (7.73 mL, 45.43 mmol). After continued stirring and cooling at −78° C. for 2 hours, the reaction was quenched with 10% aq. HCl (50 mL, 3M), the cooling bath was removed, and the reaction was allowed to warm to ambient temperature. The reaction was poured in water and extracted two times with ethyl acetate. The organics were combined, dried with MgSO4, filtered and concentrated to 8.0 grams of 6-methoxy-2,3-dihydro-1H-inden-5-ylboronic acid as a white, somewhat tacky, solid. The solid turned blue over 48 hours. The boronic acid was used without further purification.

1. temperatureThe reaction was cooled with a dry ice/acetone bath for 15 minutes
2. stirringAfter continued stirring
3. temperaturecooling at −78° C. for 2 hours
4. customthe reaction was quenched with 10% aq. HCl (50 mL, 3M)
5. customthe cooling bath was removed
6. temperatureto warm to ambient temperature
7. additionThe reaction was poured in water
8. extractionextracted two times with ethyl acetate
9. dry with materialdried with MgSO4
10. filtrationfiltered
11. concentrationconcentrated to 8.0 grams of 6-methoxy-2,3-dihydro-1H-inden-5-ylboronic acid as a white, somewhat tacky, solid
12. waitThe solid turned blue over 48 hours
13. customThe boronic acid was used without further purification

ORD record

ord-d95768b072d74b159827ac7430f13d8e

Source dataset

uspto-grants-2005_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06964965B2