(5,6-Dihydro-1,4-dithiin-2-yl)methanol as a Versatile Allyl-Cation Equivalent in (3+2) Cycloaddition Reactions
作者:Jan Hullaert、Johan M. Winne
DOI:10.1002/anie.201606411
日期:2016.10.10
instrumental for efficient cycloaddition reactions to take place, thus indicating an attractive strategy for controlling the reactivity of heteroatom‐substituted allyl cations. The formal cycloaddition reaction is highly regio‐ and stereoselective and was also used for a short totalsynthesis of the natural product cuparene in racemic form through a cycloaddition–hydrodesulfurization sequence.
Stereoselective Rhodium-Catalyzed Isomerization of Stereoisomeric Mixtures of Arylalkenes
作者:Tao Li、Wanxiang Zhao、Hongxuan Yang、Wenke Dong、Wencan Wang
DOI:10.1055/s-0040-1707166
日期:2020.10
Abstract A new efficient method for the synthesis of a high ratio of E-alkenes from E/Z mixtures of alkenes with B2pin2 in the presence of a rhodium catalyst is described. This reaction features mild reaction conditions, broad functional group tolerance, and highly great application potential.
biphenyl phosphoramidites bearing a D2-symmetric biphenyl backbone was prepared and applied as chiral ligands in the copper-catalyzedallylicalkylation with Grignard reagent. The alkylation products were obtained in quantitative yields with high regioselectivities up to 94:6 of SN2′/SN2 ratio and enantiomeric excesses up to 91.1% for SN2′ products. The unique D2-symmetric backbone ligands have the
制备了一类新型的具有D 2-对称联苯骨架的对映体双桥联苯二亚磷酰胺,并将其用作手性配体,用格氏试剂在铜催化的烯丙基烷基化反应中使用。烷基化产物以定量产率获得,具有高达S N 2'/ S N 2之比的94:6的高区域选择性,并且对于S N 2'产物,对映体过量高达91.1%。独特的D 2-对称主链配体的优点是易于制备,并且其关键中间体可以从不希望的异构体中充分利用。
CF3CO2ZnEt-mediated highly regioselective rearrangement of bromohydrins to aldehydes
A highly efficient and selective rearrangement reaction of bromohydrins to aldehydes mediated by CF3CO2ZnEt was described. The secondary and tertiary aldehydes were prepared under mild conditions in good to excellent yields (85–99%). The scope and limitations of this rearrangement process were also investigated.
描述了由CF 3 CO 2 ZnEt介导的溴代醇对醛类的高效选择性重排反应。仲醛和叔醛是在温和的条件下以良好至极佳的收率(85–99%)制备的。还研究了这种重排过程的范围和局限性。