Ethanol → 2-Phenyldibenzo[b,d]thiophene

Participants

Reaction Steps

2-bromo-dibenzo[b,d]thiophene (10 g), phenylboronic acid (5.1 g) tetrakis(triphenylphosphine)palladium (2.2 g) and potassium carbonate (18.38 g) were refluxed in a mixture of toluene (110 mL), ethanol (20 mL) and water (90 mL) overnight. The reaction was quenched with water and the toluene layer was removed and passed through a celite column and the toluene layer was evaporated in a rotary evaporator to yield 5.2 g 2-phenyl-dibenzo[b,d]thiophene. 2-phenyldibenzo[b,d]thiophene (5.2 g) was dissolved in anhydrous tetrahydrofuran (50 mL) under nitrogen atmosphere, and the solution was then cooled to −78° C. 20.0 mL of n-butyl lithium (1.6 M solution) was added dropwise into the reaction mixture, and continuously stirred to equilibriate to room temperature. The reaction mixture was then cool to −60° C., and trimethyborate (5.67 mL) was added and the reaction was allowed to stir overnight. The reaction was then quenched with 20% aqueous hydrochloric acid, and extracted the organic layer with ethyl acetate; ethyl acetate layer was then washed thoroughly with water and dried over anhydrous sodium sulfate, and was evaporated to dryness to yield 4.2 g of 8-phenyldibenzo[b,d]thiophene-4-boronic acid.

Provenance & Evidence