The preliminary results of a study on the stereocontrolled racemic synthesis of thaxtomins A and B are disclosed. The synthesis features a new C-C bond-forming reaction: dilithium tetrachlorocuprate was shown to be an efficient catalyst for cross-coupling reactions of lithiated 1,4-dialkyl-2,5-piperazinedione anions with gramine methosulfate and alkyl halides.