Water → 5-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)thiophene-2-carboxylic acid

HRID 1099112Notes

Reaction equation

[OH:1][B:2]([OH:11])[C:3]1[S:7][C:6]([C:8]([OH:10])=[O:9])=[CH:5][CH:4]=1.O[C:13]([C:16](O)([CH3:18])[CH3:17])([CH3:15])[CH3:14].O>C1(C)C=CC=CC=1>[CH3:14][C:13]1([CH3:15])[C:16]([CH3:18])([CH3:17])[O:1][B:2]([C:3]2[S:7][C:6]([C:8]([OH:10])=[O:9])=[CH:5][CH:4]=2)[O:11]1

Participants

Conditions

Temperature: 115 °C

Procedure

To a solution of 5-(dihydroxyboryl)-2-thiophenecarboxylic acid (4.0 g) in toluene (50 ml) was added pinacol (2.75 g). The reaction mixture was heated at 110-120° C. and the water set free during the reaction was continuously removed by a Dean-Stark apparatus. After 4 hours heating, the reaction mixture was cooled down to room temperature thus providing 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-thiophene-carboxylic acid as a white solid which was filtered off (4.43 g, yield: 75%) and used as such for further reaction. The pure compound was characterized by its 1H NMR spectrum (300 MHz, CD3OD) as follows: peaks at 1.42 (12H, s), 7.63 (1H, d) and 7.89 (1H, d) ppm.

Workup

customwas continuously removed by a Dean-Stark apparatus
temperatureAfter 4 hours heating
temperaturethe reaction mixture was cooled down to room temperature thus providing 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-thiophene-carboxylic acid as a white solid which
filtrationwas filtered off (4.43 g, yield: 75%)
customsuch for further reaction

Sources & evidence

ORD record: ord-e60169d28f2e4f3e997c0cd7b9ad2a00
Source dataset: uspto-grants-2012_03
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08143394B2

Reaction notes

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