A facile stereospecific synthesis of (Z)-2-sulfonyl-substituted 1,3-enynes via Sonogashira coupling of (E)-α-iodovinyl sulfones with 1-alkynes

(E)-α-Iodovinyl sulfones 1 underwent the Sonogashira coupling reactions with terminal alkynes 2 in piperidine at room temperature in the presence of 5 mol% of Pd(PPh3)4 and 10 mol% of CuI to stereospecifically afford the corresponding (Z)-2-sulfonyl-substituted 1,3-enynes 3 in high yields.