- Palladium-Catalyzed Hydrohalogenation of 1,6-Enynes: Hydrogen Halide Salts and Alkyl Halides as Convenient HX Surrogates
Petrone, D. A.; Franzoni, I.; Ye, J.; Rodriguez, J. F.; Poblador-Bahamonde, A. I.; Lautens, M.
J. Am. Chem. Soc. 2017, 139, 3546-3557
Difficulties associated with the handling H2 and CO in metal-catalyzed processes has led to the development of chemical surrogates to these species. Despite many successful examples using this strategy, the application of convenient hydrogen halide (HX) surrogates in catalysis has lagged behind considerably. We now report the use of ammonium halides as HX surrogates to accomplish a novel Pd-catalyzed hydrohalogenation of enynes. These safe and practical salts avoid many drawbacks associated with traditional HX sources including toxicity and corrosiveness. Experimental and computational studies support a reaction mechanism involving a crucial E-to-Z vinyl–Pd isomerization and a carbon–halogen bond-forming reductive elimination. Furthermore, rare examples of C(sp3)–Br and –Cl reductive elimination from Pd(II) as well as transfer hydroiodination using 1-iodobutane as an alternate HI surrogate are also presented.
open archive unige:92434