New Oxidative Ring Opening Reaction Utilizing Iodosylbenzene

最近，我们开发了一种新的、高效的碳环开环反应，通过碘（<III>）介导的< γ > -三丁基锡醇的1,4氧化裂解反应生成不饱和羰基化合物。现在我们考察了裂解反应的立体化学过程。研究发现1,4-氧化断裂以完全立体定向的方式进行，并应用于蚊子信息素红-6-乙酰氧基十六烷-5-内酯的立体选择性合成。此外，还开发了一种新的烯烃内酯扩环途径。在温和的条件下，利用（二乙酰氧基碘）苯对三丁基锡基内酯进行1,4氧化裂解，得到立体定向的不饱和中环内酯，产率高。内酯中三丁基的相对立体化学性质决定了内酯的双键几何形状。我们还发现明确的证据表明，通过锡和醚氧原子之间的分子内高价相互作用，顺-1,3-二取代环己烷的分子几何形状固定在双轴构象上。“稳定的1,3-二轴相互作用”导致高度立体选择性的双键渗透化，并产生邻二醇。

Recently, we developed a new and efficient ring opening reaction of carbocycles that yields unsaturated carbonyl compounds by iodine( <III> )-mediated oxidative 1,4-fragmentation of <gamma> -tributylstannyl alcohols. We have now examined the stereochemical course of the fragmentation reaction. The oxidative 1,4-fragmentation was found to proceed in a completely stereospecific manner and applied to the stereoselective synthesis of the mosquito pheromone, erythro-6-acetoxyhexadecan-5-olide. Furthermore, a new ring expansion route to olefinic lactones was developed. Oxidative 1,4-fragmentation of tributylstannyl lactols utilizing (diacetoxyiodo)benzece under mild conditions gave unsaturated medium-ring lactones stereosepecifically in good yields. The relative stereochemistry of tributylstannyl group of the lactols determines the double bond geometry of the lactones. We also found unambiguous evidence indicating the fixation of molecular geometry of cis-1,3-disubstituted cyclohexanes to the diaxial conformer by the intramolecular hypervalent interaction between tin and etheric oxygen atoms. The "stabilizing 1,3-diaxial interaction" results in the highly stereoselective osmylation for double bonds with production of vicinal glycols.