Carbene‐Catalyzed Enantioselective Hydrophosphination of α‐Bromoenals to Prepare Phosphine‐Containing Chiral Molecules
摘要:
AbstractDisclosed herein is the first carbene‐organocatalyzed asymmetric addition of phosphine nucleophiles to the in situ generated α,β‐unsaturated acyl azolium intermediates. Our reaction enantioselectively constructs carbon–phosphine bonds and prepares chiral phosphines with high optical purities. The phosphine products are suitable for transforming to chiral ligands or catalysts with applications in asymmetric catalysis. The diarylalkyl or trialkyl phosphine products from our catalytic reactions, air‐sensitive and reactive in nature, can be trapped (and stored) in their sulfur‐oxidized form for operational simplicities.
Efficient Assembly of Polysubstituted Pyrroles via a (3 + 2) Cycloaddition/Skeletal Rearrangement/Redox Isomerization Cascade Reaction
作者:Yuanyuan Yu、Chunyu Wang、Xinze He、Xiaotong Yao、Liansuo Zu
DOI:10.1021/ol501580b
日期:2014.7.3
redox isomerization, for the synthesis of 3-allyl pyrroles is reported. In a single step, readily accessible simple starting materials are transformed into highly substituted pyrroles with high efficiency. The products obtained contain allyl substituents, which can be readily elaborated to other useful functional groups. The reaction proceeds through an unusual (3 + 2) cycloaddition/skeletal rearrangement/redox
In contrast to well‐established asymmetric hydrogenation reactions, enantioselective protonation is an orthogonal approach for creating highly valuable methine chiral centers under redox‐neutral conditions. Reported here is the highly enantio‐ and diastereoselective hydrofluorination of enals by an asymmetric β‐protonation/α‐fluorination cascade catalyzed by N‐heterocyclic carbenes (NHCs). The two
Chemoselective N-Heterocyclic Carbene-Catalyzed Cascade of Enals with Nitroalkenes
作者:Zijun Wu、Xu Wang、Fangyi Li、Jicheng Wu、Jian Wang
DOI:10.1021/acs.orglett.5b01692
日期:2015.7.17
An unprecedented N-heterocycliccarbenecatalyzed chemoselective and enantioselective cascade reaction of enals with nitroalkenes has been developed. A wide range of enantioenriched dihydrocoumarins has been prepared, and the reaction goes through an enolate intermediate generated under a catalytic process.
Quantitative conversion of racemic propargyl alcohols into optically active propargyl esters with up to 99% ee has been achieved by lipase/oxovanadium co-catalyzed dynamic kineticresolution, which combines the lipase-catalyzed enantioselective esterification of the racemic substrates and the in situ racemization of the remaining enantiomers. The success is owed to our discovery of a magic solvent
An unprecedented highly stereoselective synthesis of pyrrolo[1,2-d][1,4]oxazepin-3(2H)-ones has been accomplished via photoredox/N-heterocycliccarbene (NHC) relay catalysis. A wide range of substituted dibenzoxazepines and aryl/hetereoaryl enals were well accommodated under the organic photoredox catalysis-promoted amine oxidation to generate the imines, followed by a NHC-catalyzed [3 + 2] annulation
通过光氧化还原/ N-杂环卡宾 (NHC) 中继催化,实现了前所未有的高度立体选择性合成吡咯并 [1,2- d ][1,4]oxazepin-3(2 H )-ones。有机光氧化还原催化促进胺氧化生成亚胺,然后进行 NHC 催化的 [3 + 2] 环化反应,以实现优异的非对映和对映选择性二苯并恶氮杂合吡咯烷酮。