Alkynes thiourea additions

The preparation of vinyl sulfides (or thioethers) has been extended by X-ray or irradiated addition of thiols to acetylene, and Pd(0Ac)2 or Pd(PPh3)4 catalyzed addition of thiol or disulfide to alkynes. In addition, alkyl halides (e.g., ethyl bromide, n-butyl bromide, 5 c-butyl bromide, benzyl chloride, etc.) have been successfully converted into corresponding vinyl sulfide through a one-pot process addition of acetylene mediated by thiourea. 

In 2010, Monge et al. reported a one-pot tandem reaction by combining bifunctional thiourea and Au complex [77], affording dihydropynole derivatives in moderate yields and high enantioselectivities. The reaction was based on a bifunctional thiourea-catalyzed Mannich-type reaction and a subsequent Au-catalyzed alkyne hydroamination and isomerization of propargylated malononitrile and N-Boc-protected imines (Scheme 9.72). Notably, acidic additive proved cracial to prevent deactivation of the gold catalyst and enhance the reactivity and selectivity. 

Addition to Multiple Bonds. Kinetic measurements of the addition of acrylic acid and its methyl ester have shown this reaction to be first-order in both thiourea and alkenes. Divinyl sulphides (27) and (28) are formed from the corresponding alkynes and thioureas, but rearrangement is observed in the reaction with diphenylacetylene to give (PhaC=CH)2S. S-Vinyl-isoselenourea (29) is obtained from the addition of selenourea to I,3-diphenylprop-2-yn-l-one,... 

---