决明和Prosopis物种的顺式 -2-甲基-6-取代的哌啶-3-醇生物碱很容易通过结合氮杂-Achmatowicz 氧化重排和二氢吡啶酮还原,然后将立体选择性烯丙基硅烷加成到N-磺酰亚胺离子上来制备。还原反应的立体化学结果可归因于假轴取向的2,6-取代基和赤道接近的氢化物试剂之间的空间位阻,这解释了通过氢化物的轴向接近而排他地形成顺式醇。通过催化还原除去( E )-甲基-戊-3-烯酸酯侧链中存在的不饱和度,并将剩余的酯基转化为相应的Weinreb's酰胺。该关键中间体用于合成阿齐米酸、脱氧卡辛、酪氨酸和香料。( S )-N-甲苯磺酰氨基呋喃16的简便制备及其向手性 Achmatowicz 氧化产物18 的转化提供了这些生物碱的正式手性合成。
Asymmetric Stepwise Reductive Amination of Sulfonamides, Sulfamates, and a Phosphinamide by Nickel Catalysis
作者:Xiaohu Zhao、Haiyan Xu、Xiaolei Huang、Jianrong Steve Zhou
DOI:10.1002/anie.201809930
日期:2019.1.2
Asymmetricreductive amination of poorly nucleophilic sulfonamides was realized in the presence of nickel catalysts and titanium alkoxide. A wide range of ketones, including enolizable ketones and some biaryl ones, were converted into sulfonamides in excellent enantiomeric excess. The cyclization of sulfamates and intermolecular reductive amination of a diarylphosphinamide were also successful. Formic
Nickel-Catalyzed Asymmetric Transfer Hydrogenation and α-Selective Deuteration of <i>N</i>-Sulfonyl Imines with Alcohols: Access to α-Deuterated Chiral Amines
A nickel-catalyzed enantioselective transferhydrogenation and deuteration of N-sulfonyl imines was developed. Excellent α-selectivity and high deuterium content were achieved by using inexpensive 2-propanol-d8 as a deuterium source. As a highlight, no deuteration of β-C–H and the remote C–H of N-sulfonyl amines occurred, which is hard to achieve using other imines or by hydrogen isotope exchange with
An efficient preparation of optically active α-furfuryl amide by kinetic resolution using the modified sharpless asymmetric epoxidation reagent
作者:Wei-Shan Zhou、Zhi-Hui Lu、Zhi-Min Wang
DOI:10.1016/0040-4039(91)80360-i
日期:1991.3
Kineticresolution of α-furfuryl amide was first carried out by using the modified Sharpless asymmetric epoxidation reagent to give the slow-reacting enantiomers, (S)-1a–f and (R)-1b,f in high enantioselectivity (90–100% e.e) and high chemical yield (45–50%).
Efficient asymmetric transfer hydrogenation of N-sulfonylimines on water
作者:Lei Wang、Qi Zhou、Chuanhua Qu、Qiwei Wang、Linfeng Cun、Jin Zhu、Jingen Deng
DOI:10.1016/j.tet.2013.05.064
日期:2013.8
and green approach for synthesis of optically active amines was developed via asymmetric transferhydrogenation of N-sulfonyl ketimines catalyzed by the chiral and lipophilic rhodium-amido complex on water. Higher reactivity and enantioselectivity were observed on the hydrogenation of the solid substrate in an aqueous suspension compared to organic homogeneous phases. In the heterogeneous aqueous reaction