Synthesis of substituted [1]benzothieno[2,3‐b]pyrazines

The synthesis of a series of novel 1‐unsubstituted and 1‐alkyl‐1,2,3,4‐tetrahydro[1]benzothieno[2,3‐b]‐pyrazine‐2,3‐diones 4a‐d and their corresponding dialkylaminoalkylamino derivatives 6a‐d starting from 2‐nitro‐3‐bromobenzo[6]thiophene is described. The title ring system has not been reported previously.