Trifluoroacetic acid → 2-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-5-amine

HRID 2199618Notes

Reaction equation

HRID 2199618 reaction equation
[CH3:1][C:2]1([CH3:26])[C:6]([CH3:8])([CH3:7])[O:5][B:4]([C:9]2[S:13][C:12]3[CH:14]=[CH:15][C:16]([NH:18]C(=O)OC(C)(C)C)=[CH:17][C:11]=3[CH:10]=2)[O:3]1.FC(F)(F)C(O)=O>ClCCl>[CH3:1][C:2]1([CH3:26])[C:6]([CH3:7])([CH3:8])[O:5][B:4]([C:9]2[S:13][C:12]3[CH:14]=[CH:15][C:16]([NH2:18])=[CH:17][C:11]=3[CH:10]=2)[O:3]1

Participants

4

Reactant 2

HCID 6422Trifluoroacetic acidHCID 131735691Tert-butyl (2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-5-yl)carbamate

Product 1

HCID 1254677282-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-5-amine

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Conditions

Temperature
0 °C

Procedure

To the solution of tert-butyl (2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-5-yl)carbamate (7.51 g, 20 mmol, 1 eq) in anhydrous dichloromethane (40 mL under nitrogen atmosphere at 0° C. was added dropwise trifluoroacetic acid (15.4 mL, 10 eq) and the reaction was stirred at 0° C. for 30 minutes followed by at room temperature for about two hours. The reaction was then slowly poured into an ice-cold saturated aqueous sodium bicarbonate solution with stirring and the white solid that appeared during the process was filtered, washed with water, to give a first batch of 2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-5-amine in the amount of 2.792 g. The pH of the filtrate was adjusted to 8 by addition of solid sodium bicarbonate with stirring and then extracted using chloroform (3×). All organic layers were combined, dried with anhydrous sodium sulfate, and concentrated down to give brown oil. After the oil was placed in vacuo for two hours, it was treated with EtOAc-Hex (1:9) and the mixture was stirred at room temperature for 30 minutes. A second batch of 2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-5-amine was isolated as a pale pink solid in the amount of 1.883 g upon filtration. The total amount of 2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-5-amine is 4.675 g with a yield of 85%.

Workup

  1. waitfollowed by at room temperature for about two hours
  2. stirringwith stirring
  3. filtrationwas filtered
  4. washwashed with water

Sources & evidence

ORD record
ord-ee57489039ed474fa85f4054b5885aa0
Source dataset
uspto-grants-2016_06
Patent number
US09359336B2

Reaction notes

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