Maxim D. Gotsko

Expedient Strategy for the Synthesis of 5-Acylethynylpyrrole-2-carbaldehydes

Abstract 5-Acylethynylpyrrole-2-carbaldehydes have been synthesized from the protected pyrrole-2-carbaldehydes by their transition-metal-free topochemical mechanoactivated ethynylation with acylbromoacetylenes in a solid Al2O3 medium (room temperature, 6 h, 41–54% yields). GRAPHICAL ABSTRACT

Transition metal-free cross-coupling of furan ring with haloacetylenes

Abstract On the example of menthofuran, a naturally abundant compound, it has been shown for the first time that the furan ring can be readily cross-coupled with acylhaloacetylenes in the solid Al2O3 powder at room temperature to afford the corresponding 2-ethynyl derivatives in up to 88% yield. The reaction represents a ring closing/ring opening process that includes reversible formation of the intermediate cycloadducts further producing acetylene derivatives with elimination of HHal.