2-硝基苯并呋喃和α-芳基-α-异氰基乙酸酯的非对映和对映选择性脱芳香形式[3 + 2]环加成得到带有3 a ,8 b -二氢-1 H -苯并呋喃[2,3- c ]的三环化合物具有三个连续立体中心的吡咯框架。该反应是通过铜醚有机催化剂实现的。获得的反应产物具有几乎完全的非对映选择性,并且对于许多取代的2-硝基苯并呋喃和异氰乙酸酯具有优异的对映体过量。
2-硝基苯并呋喃和α-芳基-α-异氰基乙酸酯的非对映和对映选择性脱芳香形式[3 + 2]环加成得到带有3 a ,8 b -二氢-1 H -苯并呋喃[2,3- c ]的三环化合物具有三个连续立体中心的吡咯框架。该反应是通过铜醚有机催化剂实现的。获得的反应产物具有几乎完全的非对映选择性,并且对于许多取代的2-硝基苯并呋喃和异氰乙酸酯具有优异的对映体过量。
Supported and Unsupported Chiral Squaramides as Organocatalysts for Stereoselective Michael Additions: Synthesis of Enantiopure Chromenes and Spirochromanes
作者:José M. Andrés、Jorge Losada、Alicia Maestro、Patricia Rodríguez-Ferrer、Rafael Pedrosa
DOI:10.1021/acs.joc.7b01177
日期:2017.8.18
Novel supported chiral bifunctional squaramides have been easily prepared starting from diamines derivedfrom natural amino acids and commercially available aminoalkyl polystyrene resins. These squaramides behave as excellent stereoselective recoverable organocatalysts in different Michael additions, in neat conditions at room temperature. The reaction on 2-(2-nitrovinyl) phenol as electrophile lead
Asymmetric Organocatalytic Cascade Michael/Hemiketalization/Retro-Aldol Reaction of 2-[(<i>E</i>)-2-Nitrovinyl]phenols with 2,4-Dioxo-4-arylbutanoates: A Convenient Access to Chiral α-Keto Esters
unprecedented organocatalyticenantioselective cascade Michael/hemiketalization/retro‐aldol reaction of 2‐[(E)‐2‐nitrovinyl]phenols and 2,4‐dioxo‐4‐arylbutanoates is described. With a bifunctional squaramide catalyst incorporating (1R,2R)‐1,2‐diphenylethane‐1,2‐diamine, the reactions afford products in 75–99% yields with 80–98% ee. This process provides an enantioselective pathway for the synthesis of chiral
Organocatalytic Asymmetric Tandem Michael Addition−Hemiacetalization: A Route to Chiral Dihydrocoumarins, Chromanes, and 4<i>H</i>-Chromenes
作者:Dengfu Lu、Yajun Li、Yuefa Gong
DOI:10.1021/jo101446d
日期:2010.10.15
Asymmetric tandem Michael addition−hemiacetalization between aliphatic aldehydes and (E)-2-(2-nitrovinyl)phenols was investigated for constructing benzopyran backbones. Interestingly, the diastereo- and enantioselectivities changed markedly when the reaction was mediated by different types of secondary amine catalysts. The diphenylprolinol silyl ether 7 promoted the reaction with excellent enantioselectivities
Stereocontrolled construction of 3H-furo[3,4-b]chromen-1(9H)-one scaffolds via organocatalyzed Michael addition and the following intramolecular dehydration
An efficient approach for the stereocontrolledconstruction of 3H-furo[3,4-b]chromen-1(9H)-oneskeleton has been successfully developed through a sequential Michael addition/intramolecular dehydration strategy. The Michael addition of tetronic acid to 2-((E)-2-nitrovinyl)phenols catalyzed by a bifunctional squaramide derived from L-tert-leucine, and the subsequent intramolecular dehydration promoted
通过顺序迈克尔加成/分子内脱水策略,成功开发了一种立体控制3 H-呋喃并[3,4- b ] chromen-1(9 H)-骨架的有效方法。迈克尔加成特窗酸的2 - ((Ë)-2-硝基乙烯基)苯酚通过衍生自双官能squaramide催化大号-叔-亮氨酸,和由浓硫酸促进了随后的分子内脱水,顺利进行,得到相应的药学上有价值的3 H-呋喃并[3,4- b ] chromen-1(9 H)-one,可接受的收率为ee的79–97%。
Organocatalytic asymmetric Michael/hemiketalization/acyl transfer reaction of 1,3-propanediones with (<i>E</i>)-2-(2-nitrovinyl)phenols
作者:Nimisha Bania、Subhas Chandra Pan
DOI:10.1039/c8ob01771a
日期:——
An organocatalyticasymmetriccascadeMichael/hemiketalization/acyl transfer reaction between (E)-2-(2-nitrovinyl)phenols and 1,3-propanediones is disclosed. A cinchona alkaloid derived bifunctional thiourea catalyst was found to be the most effective for this reaction and provided the desired products in moderate to good yields with good to high enantioselectivities.