Palladium-Catalyzed Synthesis of (Z)-3-Arylthioacrylic Acids and Thiochromenones

초록

The three-component reaction of aryl halides, sodium sulfide pentahydrate (Na2S5H2O), and propiolic acid in the presence of 2.5% bis(triphenylphosphine)palladium chloride [Pd(PPh3)2Cl2], 5% 1,4-bis(diphenylphosphino)butane (dppb) and 2equivalents of 1,8-diazabicycloundec-7-ene (DBU) produces stereoselectively (Z)-3-arylthioacrylic acids in good yields. A study of the reaction pathway suggested that the CS bond formation between aryl halides and Na2S5H2O proceeded first, and the resulting intermediate reacted with propiolic acid to produce the desired product. In addition, when the resulting product was treated with acid, the respective thiochromenones were formed in good yields.

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