1,6-dibromohexa-2,4-diene 在
氧气 、 Rose Bengal bis(triethylammonium) salt 作用下,
以
二氯甲烷 为溶剂,
反应 6.0h,
以63%的产率得到(3S,6R)-3,6-di(bromomethyl)-3,6-dihydro-1,2-dioxin
参考文献:
名称:
Osmium Catalyzed Dihydroxylation of 1,2-Dioxines: A New Entry for Stereoselective Sugar Synthesis
摘要:
A series of 3,6-substituted 3,6-dihydro-1,2-dioxines were dihydroxylated with osmium tetroxide to furnish 1,2-dioxane-4,5-diols (peroxy diols) in yields ranging from 33% to 98% and with de values not less than 90%. The peroxy diols were then reduced to generate a stereospecific tetraol core with R, R, S, S or "allitol" stereochemistry. The peroxy diols and their acetonide derivatives were also ring-opened with Co(II) salen complexes to give novel hydroxy ketones in 77-100% yield, including the natural sugar psicose. Importantly, preliminary work on the catalytic asymmetric ring-opening of meso-peroxy diols using the Co(II) Jacobsens's catalyst indicates that asymmetric sugar synthesis from 1,2-dioxines is possible.
A convenient synthesis of ( E )-conjugated polyene sulfonyl derivatives with excellent stereospecificity
作者:Chunyan Yu、Zhongwen Lv、Sheng Xu、Jun Zhang
DOI:10.1016/j.tetlet.2018.05.060
日期:2018.8
A highly selective synthesis of conjugated polyene sulfonyl derivatives is described via the elimination of disulfonyl chloride with readily accessible raw material dihaloalkane. The protocol offers a convenient way to form sulfonamides, sulfonates and even sulfones. Furthermore, this method was manipulated under mild condition with simple operation in high yield to afford only trans products.
substituent chemicalshifts (SCS) in a variety of molecules. These SCS were analysed in terms of the CN electric field, magnetic anisotropy and steric effects for protons more than three bonds removed together with a model (CHARGE7) for the calculation of the two‐ and three‐bond SCS. For the aromatic nitriles ring current and π‐electron effects were included. The anisotropic and steric effects of the cyano