Stereoselective Synthesis Of Functionalized (1E,5E)-1,5-Dien-3-ynes And Difunctionalized1,3-dienes

Acetylenic Sulfones and alkynyl esters were prepared according to the literatureprocedures. Acetylenic sulfones and alkynyl esters underwent the cis-additionreactions with (tirmethylsilyl)acetylene to give (E)-1-sufonyl-4-(trimethylsilyl)-1,3-enynes and (E)-1-ethoxycarbonyl-4-(trimethylsilyl)-1,3-enynes, in high yields,respectively. The addition products then underwent the desilylation reaction in thepresence of KF in methanol to afford (E)-1-sulfonyl-1,3-enynes and (E)-1-ethoxycarbonyl-1,3-enynes in high yields, respectively. The Sonogashira couplingreactions of (E)-1-sulfonyl-1,3-enynes and (E)-1-ethoxycarbonyl-1,3-enynes with(E)-alkenyl iodides in the presence of Pd(PPh3)4and CuI provide a practical methodfor the stereoselective synthesis of functionalized (1E,5E)-1,5-dien-3-ynes containingsulfonyl or ester groups.Hydrostannylation reactions of (Z)-2-sulfonyl-1,3-enynes and (Z)-2-ethoxy-carbonyl-1,3-enynes with tributyltin hydride in the presence of Pd(PPh3)4affordregio-and stereoselectively difunctionalized1,3-dienes containing tin and sulfonyl orester groups.