A strictly "pair"-selective synthesis of conjugated diynes via Pd-catalyzed cross coupling of 1,3-diynylzincs: A superior alternative to the Cadiot-Chodkiewicz reaction

[GRAPHICS] A strictly "pair"-selective synthesis of conjugated diynes via Pd-catalyzed cross coupling of 1,3-diynylzincs is described. This method, like the Cadiot-Chodkiewicz reaction, requires three steps for the synthesis of (RC)-C-1=CC=CR2 from (RC)-C-1=CH, (RX)-X-2, and HC=CH. However, the high "pair"-selectivity permitting high yield production of the desired conjugated diynes without separation of symmetrical diynes promises to make the present protocol superior to the Cadiot-Chodkiewicz reaction in many cases.