Enantioselective Total Syntheses of Kuwanon X, Kuwanon Y, and Kuwanol A was written by Gao, Lei;Han, Jianguang;Lei, Xiaoguang. And the article was included in Organic Letters in 2016.Reference of 338454-02-7 This article mentions the following:
The first enantioselective total syntheses of (-)-kuwanon X (I), (+)-kuwanon Y (II), and (+)-kuwanol A (III) have been accomplished by using asym. Diels-Alder cycloaddition promoted by chiral VANOL or VAPOL/boron Lewis acid. The biosynthesis-inspired asym. Diels-Alder cycloaddition shows high exo selectivity (exo/endo = 13/1), which was unprecedented in the previous total syntheses of related prenylflavonoid Diels-Alder natural products. An acid catalyzed intramol. ketalization process enabled a biomimetic transformation to construct the polycyclic skeleton of kuwanol A efficiently. In the experiment, the researchers used many compounds, for example, Methyl 3,5-dihydroxy-4-iodobenzoate (cas: 338454-02-7Reference of 338454-02-7).
Methyl 3,5-dihydroxy-4-iodobenzoate (cas: 338454-02-7) belongs to iodide derivatives. Iodide-containing intermediates are common in organic synthesis, because of the easy formation and cleavage of the C–I bond. The C–I bond is the weakest of the carbon–halogen bonds. These bond strengths correlate with the electronegativity of the halogen, decreasing in the order F > Cl > Br > I. This periodic order also follows the atomic radius of halogens and the length of the carbon-halogen bond.Reference of 338454-02-7
Referemce:
Iodide – Wikipedia,
Iodide – an overview | ScienceDirect Topics – ScienceDirect.com