Asymmetric Synthesis of Chiral Chromanes by Copper‐Catalyzed Hydroamination of 2
<i>H</i>
‐Chromenes
作者:Qingjing Yang、Sifeng Li、Jun (Joelle) Wang
DOI:10.1002/cctc.202000601
日期:2020.6.18
A copper/(R )‐DTBM‐SEGPHOS‐catalyzed enantioselective hydroamination of 2H ‐chromenes employing hydrosilanes and hydroxylamine esters has been developed. This protocol offers a highly efficient and direct route for accessing a series of 4‐aminochromanes in 50–88 % yields with 59–99 % enantioselectivities under mild reaction conditions.
Zr-Catalyzed Olefin Alkylations and Allylic Substitution Reactions with Electrophiles
作者:Judith de Armas、Stanley P. Kolis、Amir H. Hoveyda
DOI:10.1021/ja000693j
日期:2000.6.1
Disubstituted aryl olefins undergo efficient alkylations in the presence of 5 mol % Cp2ZrCl2, n-BuMgCl, and alkyl tosylates or alkyl bromides. In one class of reactions (Table 1), the resulting alkyl zirconocene (initial alkylation product) undergoes β-hydride abstraction with a hydrogen atom from within the substrate to afford allylic alkylation products (Scheme 5). In another category of reactions, where cyclic
Kinetic Resolution and Dynamic Kinetic Resolution of Chromene by Rhodium‐Catalyzed Asymmetric Hydroarylation
作者:Qingjing Yang、Yanbo Wang、Shihui Luo、Jun (Joelle) Wang
DOI:10.1002/anie.201900721
日期:2019.4.8
A highly efficient kineticresolution and dynamickineticresolution of chromene is reported for the first time and they procced by a rhodium‐catalyzed asymmetric hydroarylation pathway. This new approach offers versatile access to various chiral 2,3‐diaryl‐chromanes containing vicinal stereogenic centers, as well as the recovered chiral flavenes, in high yields with excellent ee values (s factor up