Regio- and stereoselective hydrohalogenation of ynamide components in 1,3-butadiynes with in situ generated HX

Catalytic Hydrofunctionalization Reactions of 1,3-Diynes

“…Hydrohalogenations using aqueous or gaseous HX under CuCl catalysis were described in early reports, but the yields reached were, in general, very low and the reactions led, in most cases, to isomeric mixtures of products (a representative example is given in Scheme 70) [202][203][204]. In a more recent study, regio-and stereoselective hydrohalogenation reactions of 1,3-diynes containing ynamide moieties were described by Iwasawa and colleagues under catalyst-free conditions (Scheme 71) [205]. The corresponding HX reagent was generated in situ by hydrolysis of the respective halotrimethylsilane Me 3 SiX (TMSX; X = Cl, Br, I).…”

α-Haloenamides: Synthesis and Subsequent Transformations

“…Disubstituted ynamides 8 and terminal N-tosyl-ynamides 9 were used as starting materials, the protocol was also applied to N-tosylated buta-1,3-diyne-1,4-diamines. 10 The hydrogen halide (X = I, Br) was generated in situ from mixing 1 M halotrimethylsilane in DCM with several disubstituted ynamides at -78 °C for 15 min and then adding 20 equiv of water while allowing the reaction to warm up to 0 °C. The reaction afforded a wide variety of new (E)--haloenamides in high yields (Scheme 5).…”

A Highly Regio- and Stereoselective Syntheses of α-Halo Enamides, Vinyl Thioethers, and Vinyl Ethers with Aqueous Hydrogen Halide in Two-Phase Systems

“…Similarly, α-halo vinyl thioethers and α-halo vinyl ethers are also ubiquitous building blocks in organic synthesis, material chemistry, and industrial chemicals. , The development of general synthetic protocols to access these motifs has attracted extensive interest, and a plethora of strategies have been developed (Scheme ). − Hsung et al first reported the stereoselective syntheses of α-haloenamides from ynamides using HX generated in situ . Afterward, some elegant methods have been independently reported by Iwasawa, Kazmaier, Sahoo, and Shin for the syntheses of α-haloenamides.…”

“… − Hsung et al first reported the stereoselective syntheses of α-haloenamides from ynamides using HX generated in situ . Afterward, some elegant methods have been independently reported by Iwasawa, Kazmaier, Sahoo, and Shin for the syntheses of α-haloenamides. Xu et al achieved the stereocontrolled hydrochlorination, hydrobromination and hydrofluorination of ynamides using the DMPU/HX system and KF/HFIP system, respectively .…”