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 Synthesis of Functionalized Chromans via a One-Pot Organocatalytic Domino Michael-Hemiacetalization or -Lactonization and Dehydration Sequence
Starting from2-(nitrovinyl)phenols and various cyclic dicarbonyl nucleophiles, a one-pot thiourea-catalyzed diastereo- and enantioselective synthesis of polyfunctionalized chroman derivatives via a domino Michael-hemiacetalization and dehydration sequence as well as via a domino Michael-lactonization reaction is reported. Cyclopenta[b]chromenes, tricyclic spirochromans, and tetrahydro-1H-xanthenes
从2-(硝基乙烯基)苯酚和各种环状二羰基亲核试剂开始,通过多米诺米歇尔半缩醛化和脱水序列以及多米诺米歇尔-内酰胺化反应,通过一锅硫脲催化的非对映和对映选择性合成多官能化苯并二氢吡喃衍生物。报告。环戊二烯并[ b ]色烯,三环spirochromans,和四氢ħ -xanthenes轴承的各种官能团的可以以这种方式以良好至优异的产率(56-91%)合成并具有非常好的diastereo-(88-99% de)和对映选择性(83-99%ee)。 有机催化-多米诺反应-硫脲-一锅法-色原
Organocatalytic Asymmetric Synthesis of Functionalized 4H-Chromenes via a One-Pot Domino Michael-Hemiacetalization and Dehydration Sequence
作者:Dieter Enders、Gregor Urbanietz、Gerhard Raabe
DOI:10.1055/s-0030-1260017
日期:2011.6
A one-pot thiourea-catalyzedenantioselectivesynthesis of polyfunctionalized 4H-chromenes via a domino Michael-hemiacetalization reaction and subsequent dehydration is reported. Starting from 2-nitrovinylphenols and β-keto esters, the new protocol affords the 4H-chromenes bearing a variety of functional groups with good to excellent yields (76-95%) and enantioselectivities ranging from 30-99% ee.
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
Enantioselective organocatalytic domino Michael–acetalization–Henry reactions of 2-hydroxynitrostyrene and aldehyde for the synthesis of tetrahydro-6H-benzo[c]chromenones
作者:Bor-Cherng Hong、Prakash Kotame、Ju-Hsiou Liao
DOI:10.1039/c0ob00834f
日期:——
Asymmetric domino Michael–acetalization reactions of 2-hydroxynitrostyrene and aldehydes “on water” followed by oxidation providing the cis-3,4-disubstituted dihydrocoumarins with excellent enantioselectivities (up to >99% ee). The variant with glutaraldehyde underwent a highly stereoselective domino Michael–acetalization–Henry reaction to afford the tetrahydro-6H-benzo[c]chromen-6-ones after the subsequent
不对称多米诺骨牌迈克尔缩醛化反应 2-羟基硝基苯乙烯 和醛“上 水然后进行氧化,使顺式-3,4-二取代的二氢香豆素具有出色的对映选择性(高达> 99%ee)。具有的变体戊二醛进行高度立体选择性的多米诺骨牌Michael-缩醛化-Henry反应,在随后的氧化反应后得到四氢-6 H-苯并[ c ] chromen-6-one。