Hydrochloric Acid → Quinoxaline

Participants

Reaction Steps

In a reactor in a nitrogen atmosphere, while a solution (about 25 ml) of about 3.5 g (about 5.0 mmol) of 5,8-dibromoquinoxaline derivative synthesized in Preparative Example 1 (see: T. Yamamoto, et al. J. Am. Chem. Soc, 1996, Vol. 118, pp. 3930˜3937) and an excess of 2-thiophene borane derivative (about 15.0 mmol) in anhydrous THF was stirred, aqueous potassium carbonate (K2CO3, about 20 g, about 150 mmol) and about 10 mol % (about 578 mg, about 0.5 mmol) of a palladium catalyst (Pd(PPh3)4), based on the monomer, were added, and then the solution was allowed to react at about 80° C.˜about 85° C. for about 24 hours. The resultant reaction solution was treated with dilute aqueous hydrochloric acid and then extracted with chloroform. The obtained organic layer was distilled under reduced pressure, slightly washed with methanol, and dried, to thus prepare a thiophene-quinoxaline trimer, which was then reacted with NBS in a mixture of chloroform and acetic acid, thereby obtaining an orange solid thiophene-quinoxaline derivative (Yield: about 72%).

Provenance & Evidence