Science of Synthesis

Marciniszyn, J. P.; Kretzschmar, M.; Gulder, T., Science of Synthesis Knowledge Updates, (2024) 3, 461.

Epoxides are the most suitable substrate class for synthesizing 1-iodo-n-heteroatom-functionalized alkanes (n = 2) because of the high reactivity of the epoxide functionality toward nucleophilic iodine sources. The important 1-iodo-2-hydroxy-functionalized building blocks are formed by opening the three-membered, oxygen-containing rings, and these transformations were described in detail in Section 35.3.5.2 in 2007.[‌1‌] Since 2007, two additional methods have been published that do not significantly extend the already known substrate scope and are thus not described here in detail. The first of these employs elemental iodine as an epoxide-opening reagent, together with the organocatalytic meso-tetraphenylporphyrin (H2TPP) system,[‌2‌] while the second method utilizes the degradative α-elimination of lithium carbenoids to achieve the epoxide ring opening.[‌3‌] New developments in this area that do extend the substrate scope include transformations of other cyclic ethers, with larger ring sizes, which require more reactive reagents than those used for epoxide opening due to their greater ring stability. In this regard, between 2007 and 2023, three novel methods were reported in the literature. These transformations lead to 1-iodo-n-heteroatom functionalized alkanes (n ≥3), but are also applicable to the generation of 1-iodo-2-hydroxyethane derivatives (n = 2) by the opening of epoxides.

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