One-step synthesis of dialkynyl-1,2-diones and their conversion to fused pyrazines bearing enediyne units

Article abstract of DOI:10.1016/S0040-4020(97)01007-7

A convenient procedure for the preparation of symmetrically end-protected dialkynyl-1,2-diones 3 from lithium acetylides and oxalyl chloride in the presence of CuBr and LiBr is described. The condensation of 3 with various aromatic and heteroaromatic 1,2-diamines leads to pyrazine-based α-dialkynylated heterocycles. The enediyne substructure of diethynylquinoxaline can be thermally rearranged in a Bergman cyclization reaction.