N-Heterocyclic Carbene Catalyzed Cyclocondensation of α,β-Unsaturated Carboxylic Acids: Enantioselective Synthesis of Pyrrolidinone and Dihydropyridinone Derivatives
作者:Xiang-Yu Chen、Zhong-Hua Gao、Chun-Yu Song、Chun-Lin Zhang、Zhi-Xiang Wang、Song Ye
DOI:10.1002/anie.201407469
日期:2014.10.20
The catalytic cyclocondensation of in situ activated α,β‐unsaturated carboxylic acids was developed. N‐heterocyclic carbenes efficiently catalyzed the generation of α,β‐unsaturated acyl azolium intermediates from α,β‐unsaturated carboxylic acids via in situgenerated mixed anhydrides for the enantioselective [3+2] and [3+3] cyclocondensation with α‐amino ketones and alkyl(aryl)imines, respectively
Spiro indane-based phosphine–oxazoline ligands for palladium-catalyzed asymmetric arylation of cyclic N-sulfonyl imines
作者:Zhongxuan Qiu、Yanshun Li、Zhenqing Zhang、Dawei Teng
DOI:10.1007/s11243-019-00329-z
日期:2019.10
Palladium complexes of indane-based phosphine–oxazoline ligands with a spirocarbon stereogenic center were examined for asymmetric addition of arylboronic acids to cyclic N-sulfonyl imines. Excellent reaction activities (up to 99% yield) and enantioselectivities (up to 99% ee) were obtained with a broad scope of substrate.
A series of chiral phosphine‐imine ligands were synthesized starting with α‐amino acids and examined for palladium‐catalyzed asymmetric addition of arylboronic acids to cyclic N‐sulfonylimines. High catalytic activities (up to 99% yield) and high enantioselectivities (up to 98% ee) were achieved for cyclic N‐sulfonyl aldimines and ketimines with five and six‐membered ring structures.
Metal-Free Ring-Expansion Reaction of Six-membered Sulfonylimines with Diazomethanes: An Approach toward Seven-Membered Enesulfonamides
作者:An-Jie Xia、Tai-Ran Kang、Long He、Lian-Mei Chen、Wen-Ting Li、Jin-Liang Yang、Quan-Zhong Liu
DOI:10.1002/anie.201508804
日期:2016.1.22
A new metal‐free, ring‐expansion reaction of six‐membered N‐sulfonylimines with unstable diazomethanes, generated in situ from the N‐tosylhydrazones, has been developed. This reaction delivers valuable seven‐membered enesulfonamides by a Tiffeneau–Demjanov rearrangement and intramolecular proton transfer tautomerization process. Moreover, this ring‐expansion reaction can be carried out in a one‐pot