A metal-free protocol for the direct bis-arylation of 2,5-dichlorobenzoquinone with aryldiazonium salts is reported. The reactive salts are generated in situ and converted to radicals through irradiation with visible light. Reaction products precipitate from the solvent, eliminating the need for purification and thus providing a novel green method for the synthesis of versatile bis-electrophiles.

Dihydropyrrolo[1,2-a]pyrazinone rings are a class of heterocycles present in a wide range of bioactive natural products and analogues thereof. As a direct result of their bioactivity, the synthesis of this privileged class of compounds has been extensively studied. This review provides an overview of these synthetic pathways. The literature is covered up until 2020 and is organized according to the specific strategies used to construct the scaffold: fusing a pyrazinone to an existing pyrrole, employing a pyrazinone-first strategy, an array of multicomponent reactions and some miscellaneous reactions.