Asymmetric Organocatalyzed Reaction Sequence To Synthesize Chiral Bridged and Spiro-Bridged Benzofused Aminals via Divergent Pathways
作者:Ying-Han Chen、Xue-Jiao Lv、Zhi-Hao You、Yan-Kai Liu
DOI:10.1021/acs.orglett.9b01874
日期:2019.7.19
asymmetric organocatalysis-triggered reaction sequence is developed. 2-Hydroxy cinnamaldehydes and cyclic N-sulfonyl ketimines were both used as multisite substrates (more than two reactive sites) to accessstructurallydiverse chiral bridged and spiro-bridged benzofused aminal derivatives, where an inseparable equilibrating mixture of isomers can be regioselectively converted into bridged benzofused
Organocatalytic Enantioselective Formal [4 + 2] Cycloaddition of Enones with Cyclic <i>N</i>-Sulfonylimines and Methylene Chromene for Chiral Spirocyclic Compounds
作者:Jie Fei、Qingqing Qian、Xiaohua Sun、Xiaodong Gu、Chuncheng Zou、Jinxing Ye
DOI:10.1021/acs.orglett.5b02667
日期:2015.11.6
A highly enantioselective synthesis of spirocycles and bridged rings has been developed through a formal [4 + 2] cycloadditionreaction between enones and N-sulfonylimines. The unprecedented strategy has been realized utilizing N-sulfonylimine as a novel dienophile through enamine–iminium tautomerism of N-sulfonylimine. In addition, a γ,ε-regioselective cycloadditionreaction proceeded by employing
N‐Heterocyclic Carbene Catalyzed Asymmetric Synthesis of Pentacyclic Spirooxindoles via [3+3] Annulations of Isatin‐Derived Enals and Cyclic N‐Sulfonyl Ketimines
A convenient enantioselective route to new types of pentacyclic spirooxindoles via [3+3] annulation reactions of isatin‐derived enals and cyclic N‐sulfonyl ketimines, using N‐heterocyclic carbene (NHC) catalysis has been developed. The new protocol leads to pentacyclic spirooxindoles bearing a quaternary spiro‐stereocenter in good yields and good to high enantiomeric ratios.
Generation of α-Iminyl Radicals from α-Bromo Cyclic <i>N</i>
-Sulfonylimines and Application to Coupling with Various Radical Acceptors Using a Photoredox Catalyst
Visible‐light‐induced generation of α‐iminyl radicals was accomplished using α‐bromo cyclic N‐sulfonylimines and photoredox catalysts such as erythrosine B or Ru(bpy)3(PF6)2. The generated α‐iminyl radical was utilized for various radical reactions with allylation reagents, silyl enol ethers and allenyl stannane to give the corresponding coupling products. Furthermore, atom transfer radical addition
Catalytic Enantioselective Aza-Reformatsky Reaction with Cyclic Imines
作者:Lode De Munck、Carlos Vila、M. Carmen Muñoz、José R. Pedro
DOI:10.1002/chem.201604606
日期:2016.12.5
A catalytic highly enantioselective aza‐Reformatsky reaction with cyclic aldimines and ketimines for the synthesis of chiral β‐amino esters with good yields and excellent enantioselectivities is reported. A readily available diaryl prolinol is used as a chiral ligand, ZnMe2 as a zinc source and ethyl iodoacetate as reagent in the presence of air atmosphere. The reaction with cyclic ketimines generates