Regio- and Stereoselective Synthesis of 1,2-Dihaloalkenes Using In-Situ-Generated ICl, IBr, BrCl, I2, and Br2

Abstract

We describe a catalyst-free 1,2-trans-dihalogenation of alkynes with an unprecedented substrate scope and exclusive regio-and stereoselectivity. This versatile dihalogenation system-a combination of NX 1 S electrophile and alkali metal halide (MX 2 ) in acetic acid-is applicable for diverse categories of alkynes (electron-rich or poor alkynes, internal and terminal alkynes, or heteroatoms such as O-, N-, S-substituted alkynes). The hydrogen bonding donor solvent acetic acid is essential for the in-situ generation of X 1 X 2 electrophile, including ICl, IBr, BrCl, I 2, and Br 2 .

Haloalkenyl Imidoyl Halides as Multifacial Substrates in the Stereoselective Synthesis of N‐Alkenyl Compounds

“…[26,27] Since the discovery of metal-catalyzed cross-coupling reactions, [28] haloalkenes and 1,2-dihaloalkenes are extensively utilized in the construction of geometrically defined alkenes. [29][30][31][32] Moreover, alkenyl halides are included in many biologically active compounds, such as pharmaceuticals [33] or agrochemicals. [34] On the other hand, imidoyl halides (aza-analogs of acyl halides) are intermediates widely utilized in the synthesis of nitrogen-containing compounds.…”

Characterising Supramolecular Architectures in Crystals Featuring I⋯Br Halogen Bonding: Persistence of X⋯X’ Secondary-Bonding in Their Congeners

“…The result is the formation of 10-membered {• • • IC 3 Br} 2 synthons and a linear tape, as highlighted in Figure 7b. The next series of one-dimensional chains has I• • • Br interactions within a zigzag topology, as found in the crystals of 21 [61], 22 [62], 23 [63], 24 [64], 25 [65] and 26 [66]. The common crystallographic features of the solvent-free crystals, with the exception of 25, are the presence of a single molecule in the asymmetric unit and the generation of the zigzag chain by glide symmetry.…”

“…The remaining zigzag chains, that is, in crystals 24 [64], 25 [65] and 26 [66], do not exhibit great differences between the C-I• • • Br and C-Br• • • I angles, with the former being the wider only in the case of 24; the chain in 26 is shown in Figure 8b. Comprising the largest subset of one-dimensional assembles, the are 13 crystals featuring helical chains, namely 27 [66], 28 [67], 29-31 [68], 32 [69], 33 [70], 34 [71], 35 [72], 36, 37 [73], 38 [74] and 39 [68]. A high degree of homogeneity again exists among the solvent-free crystals with all helical chains being propagated by 2 1 screw symmetry.…”

Stereodivergent synthesis of β-iodoenol carbamates with CO2viaphotocatalysis

“… 13 Although many methods based on halofunctionalization of alkynes or hydrofunctionalization of haloalkynes have been established for producing these compounds, their stereodivergent synthesis and stereospecific transformation still remain a great challenge ( Scheme 1a ). 14 …”