Department of Material and Life Science, Graduate School of Engineering, Osaka University , 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Org Lett. 2016 Mar 18;18(6):1246-9. doi: 10.1021/acs.orglett.6b00064. Epub 2016 Mar 7.
Stereoselective oxidative cyclization of 1,5-dienes with hydrogen peroxide catalyzed by Os(III)(OH)(H2O)(L-N4Me2)2 (1: L-N4Me2 = N,N'-dimethyl-2,11-diaza-3,3pyridinophane) is explored. 1,5-Dienes involving geraniol derivatives are converted to the corresponding tetrahydrofurans in modest to high yields. The products exclusively have the cis-conformation with respect to the substituents at the 2- and 5-positions of the tetrahydrofuran ring. The products also have a syn-conformation with respect to the furan oxygen atom and the hydroxyl groups. Mechanistic studies including a direct reaction of the oxo-hydroxo-osmium(V) complex, 2, with a dihydroxylated geraniol derivative are performed.
Os(III)(OH)(H2O)(L-N4Me2)2（1：L-N4Me2 = N,N'-二甲基-2,11-二氮杂-3,3吡啶并菲）催化下 1,5-二烯与过氧化氢的立体选择性氧化环化反应得到了探索。涉及香叶醇衍生物的 1,5-二烯转化为相应的四氢呋喃，产率中等至较高。产物在四氢呋喃环的 2-和 5-位取代基方面仅具有顺式构象。产物相对于呋喃氧原子和羟基也具有顺式构象。进行了包括氧-羟高铁(V)配合物 2 与二羟基化香叶醇衍生物的直接反应在内的机理研究。
