Trimethyl borate → (3-Chlorophenyl)boronic acid

Temperature

0 °C

A solution of trimethylborate in 200 mL of ethyl ether was cooled to -65° C. 3-Chlorobenzene magnesium chloride (0.8M, 60 mL), i.e., a grignard reagent, was added to the solution in a dropwise manner over 20 minutes. The mixture was kept in the temperature range of -60° C. to -70° C. and stirred. After 30 minutes, the mixture was allowed to warm to 0° C. and stirred for 1 hour. The mixture was quenched with H2O (25 mL) and stirred at room temperature for 1 hour. The solvent was removed and the remaining mass was extracted with ethyl ether (3×100 mL). The organic layers were combined and washed with H2O (2×50 mL), dilute HCl (2×100 mL), H2O (2×50 mL) and brine 1×50 mL). The organic layer was dried with MgSO4 and concentrated, and 100 mL of hexanes was added, and the mixture stirred for 1 hour. The resultant white precipitate was filtered off and allowed to air dry, yielding 4.6 g of 3-chlorobenzene boronic acid, a compound of Formula 4 where R4 is 3-chlorophenyl, as a white solid.

1. customwas kept in the temperature range of -60° C. to -70° C.
2. stirringstirred for 1 hour
3. customThe mixture was quenched with H2O (25 mL)
4. stirringstirred at room temperature for 1 hour
5. customThe solvent was removed
6. extractionthe remaining mass was extracted with ethyl ether (3×100 mL)
7. washwashed with H2O (2×50 mL), dilute HCl (2×100 mL), H2O (2×50 mL) and brine 1×50 mL)
8. dry with materialThe organic layer was dried with MgSO4
9. concentrationconcentrated
10. addition100 mL of hexanes was added
11. stirringthe mixture stirred for 1 hour
12. filtrationThe resultant white precipitate was filtered off
13. customto air dry

ORD record

ord-687e9e3898a54ae9a2e7e886e9f18805

Source dataset

uspto-grants-1995_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05475003