Application of E1cB Elimination in Asymmetric Organocatalytic Cascade Reactions To Construct Polyheterocyclic Compounds
作者:Zhi-Hao You、Ying-Han Chen、Yu Tang、Yan-Kai Liu
DOI:10.1021/acs.orglett.9b03138
日期:2019.10.18
By introducing a carbon functionality at 2-position of chromane, the formal asymmetric functionalization of the 3-position of 2-substituted chromane has been realized via a highly chemo-, regio-, and stereoselective organocatalyticcascadereaction in a sequential one-pot manner involving an E1cB mechanism governed ring-opening process. Critical to our success was the design of a chiral dipeptide-based
Structural optimization of thiourea-based bifunctional organocatalysts for the highly enantioselective dynamic kinetic resolution of azlactones
作者:Albrecht Berkessel、Santanu Mukherjee、Thomas N. Müller、Felix Cleemann、Katrin Roland、Marc Brandenburg、Jörg-M. Neudörfl、Johann Lex
DOI:10.1039/b607574f
日期:——
describes the synthesis of a library of structurally diverse bifunctionalorganocatalysts bearing both a quasi-Lewis acidic (thio)urea moiety and a Bronsted basic tertiary amine group. Sequential modification of the modular catalyst structure and subsequent screening of the compounds in the alcoholytic dynamickineticresolution (DKR) of azlactones revealed valuable structure-activity relationships. In particular
Chiral amine-thioureas bearing multiple hydrogen bonding donors: highly efficient organocatalysts for asymmetric Michael addition of acetylacetone to nitroolefins
New bifunctional organocatalysts amine-thioureas bearing multiple hydrogen bonding donors were synthesized and applied in catalytic asymmetricMichaeladdition of acetylacetone to aryl and alkyl nitroolefins. Multiple hydrogen bonding donors play a significant role in accelerating reactions, improving yields and enantioselectivities.
The First Catalytic, Enantioselective Aza-Henry Reaction of an Unactivated Cyclic Imine
作者:Nilupa R. Amarasinghe、Peter Turner、Matthew H. Todd
DOI:10.1002/adsc.201200558
日期:2012.11.12
The aza-Henry reaction is an efficient route to important chiral, vicinal diamines. Reports of the asymmetric version typically use electron-deficient acyclic imines. We report the first example of a catalytic, asymmetric aza-Henry reaction on an unfunctionalized cyclic imine that gives access to enantiopure diamine derivatives under experimentally straightforward conditions. The stereocentre is established
Highly efficient construction of chiral dispirocyclic oxindole/thiobutyrolactam/chromanone complexes through Michael/cyclization cascade reactions with a rosin-based squaramide catalyst
作者:Ning Lin、Xian-wen Long、Qing Chen、Wen-run Zhu、Bi-chuan Wang、Kai-bin Chen、Cai-wu Jiang、Jiang Weng、Gui Lu
DOI:10.1016/j.tet.2018.05.052
日期:2018.7
An efficient asymmetric Michael/cyclization cascade reaction of 4-chromanones with isothiocyanato oxindoles has been revealed. Under bifunctional organocatalysis by rosin-based squaramide catalyst, a series of spiro[oxindole/thiobutyrolactam/chromanone] complexes were conveniently constructed in a highly stereoselective manner (up to 99% yields, > 20:1 dr and >99% ee). The reaction leads to the formation