Triisopropyl borate → (6-Methoxy-1-benzothiophen-2-yl)boronic acid

HRID 378367Notes

Reaction equation

[CH3:1][O:2][C:3]1[CH:4]=[CH:5][C:6]2[CH:10]=[CH:9][S:8][C:7]=2[CH:11]=1.C([Li])CCC.[B:17](OC(C)C)([O:22]C(C)C)[O:18]C(C)C>O1CCCC1.Cl.C(OCC)(=O)C>[CH3:1][O:2][C:3]1[CH:4]=[CH:5][C:6]2[CH:10]=[C:9]([B:17]([OH:22])[OH:18])[S:8][C:7]=2[CH:11]=1

Participants

Conditions

Temperature: 0 °C

Procedure

To a solution of 6-methoxybenzo[b]thiophene (18.13 g, 0.111 mol) in 150 mL of anhydrous tetrahydrofuran (THF) at -60° C. was added n-butyllithium (76.2 mL, 0.122 mol, 1.6 M solution in hexanes), dropwise via syringe. After stirring for 30 minutes, triisopropyl borate (28.2 mL, 0.122 mol) was introduced via syringe. The resulting mixture was allowed to gradually warm to 0° C. and then distributed between iN hydrochloric acid and ethyl acetate (300 mL each). The layers were separated, and the organic layer was dried over sodium sulfate. Concentration in vacuo produced a white solid that was triturated from ethyl ether hexanes. Filtration provided 16.4 g (71%) of 6-methoxybenzo[b]thiophene-2-boronic acid as a white solid. mp 200° C. (dec) 1H NMR (DMSO-d6) d 7.83 (s, 1H), 7.78 (d, J=8.6 Hz, 1H), 7.51 (d, J=2.0 Hz, 1H), 6.97 (dd, J=8.6, 2.0 Hz, 1H), 3.82 (s, 3H). FD mass spec: 208.

Workup

customThe layers were separated
dry with materialthe organic layer was dried over sodium sulfate
concentrationConcentration in vacuo
customproduced a white solid
customthat was triturated from ethyl ether hexanes
filtrationFiltration

Sources & evidence

ORD record: ord-a2c8e5bcc010474993cf02d9405a6e82
Source dataset: uspto-grants-2000_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06030986

Reaction notes

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