Stereoselective synthesis of either E- or Z-diiodoalkenes from alkynes using ICI and iodide

(E)-Di-iodination of Alkynes Using Dried Dowex H+/NaI Approach

“…In general, according to the SciFinder search, very little attention has been paid to the ( E )-di-iodinated compounds 13 – 24 , which we have prepared and can be seen in Table 1. Surprisingly, compounds 19 and 21 were totally unknown and we could find only one reference for each of the compounds 14 , 36 15 , 5 20 , 3 and 22 (37) in the literature. In addition, in the preparation of compounds 18 and 23 , only two 38,39 or three 31,40,41 methods have been described, respectively.…”

“…NMR data were comparable with those reported elsewhere. 5 1 H NMR (CDCl 3 ): δ 7.34–7.29 (m, 2H), 7.20 ( t , 1H, 5 J HH = 1.1), 7.03–6.99 (m, 1H), 6.97–6.93 (m, 2H), 4.70 (d, 2H, 5 J HH = 1.1). 13 C{ 1 H} NMR (CDCl 3 ): δ 157.6, 129.7 (2C), 121.9, 115.6 (2C), 99.2, 82.0, 74.9.…”

Approaches to Styrenyl Building Blocks for the Synthesis of Polyene Xanthomonadin and its Analogues

“…One drawback of such methodology is that the conditions for cross‐coupling are frequently more forcing than desirable for the synthesis of such intrinsically unstable products. We have shown that Heck–Mizoroki (HM) reactions can often perform well at lower temperatures than is common for Suzuki–Miyaura cross‐couplings, making this reaction potentially better suited to the construction of complex polyenes . With this in mind, we envisaged the total synthesis of xanthomonadin 1 , and its derivatives, would be an ideal test for the development of mild, polyene‐compatible methodology; more especially because we have frequently found electron deficient alkenyl coupling partners to be challenging, with extended chain lengths doing little to aid stability.…”

“…As a result, we would require one key polyenyl intermediate, which could then be coupled with the appropriate polyenyl aryl intermediates to furnish each of the three target pigments. With this in mind, we considered the synthesis of all‐ trans polyene unit 4 using our Heck–Mizoroki (HM)/iododeboronation (IDB) iterative cross‐coupling (ICC) methodology (Scheme ) which we had previously applied in the synthesis of other polyene natural products . Alternatively, if an all‐ trans heptaene 11 could be accessed, then this could be coupled directly onto suitable styrenyl and alkynyl aryl building blocks 8 – 10 .…”

Stereoselective formation of 1,2-diiodoalkenes and their application in the stereoselective synthesis of highly functionalised alkenes via Suzuki and Stille coupling reactions

“…This has resulted in a preliminary report on the stereoselective formation of either (E)-or (Z)-alkenyl diiodides from acetylenes using iodine monochloride and an iodide source. 9 Herein we report the full details of this work and demonstrate the use of alkenyl diiodides for the stereoselective formation of tri-and tetra-substituted olefins.…”