Stereoselective Glycosylation of 2-Nitrogalactals Catalyzed by a Bifunctional Organocatalyst
作者:Sandra Medina、Matthew J. Harper、Edward I. Balmond、Silvia Miranda、Giacomo E. M. Crisenza、Diane M. Coe、Eoghan M. McGarrigle、M. Carmen Galan
DOI:10.1021/acs.orglett.6b01962
日期:2016.9.2
The use of a bifunctional cinchona/thiourea organocatalyst for the direct and α-stereoselective glycosylation of 2-nitrogalactals is demonstrated for the first time. The conditions are mild, practical, and applicable to a wide range of glycoside acceptors with products being isolated in good to excellent yields. The method is exemplified in the synthesis of mucin type Core 6 and 7 glycopeptides.
Catalytic atroposelective dynamic kinetic resolutions and kinetic resolutions towards 3-arylquinolines<i>via</i>S<sub>N</sub>Ar
作者:Mariel M. Cardenas、Mirza A. Saputra、Deane A. Gordon、Andrea N. Sanchez、Nobuyuki Yamamoto、Jeffrey L. Gustafson
DOI:10.1039/d1cc04335h
日期:——
substitution (SNAr) of thiophenols into 3-aryl-2-fluoroquinolines mediated by catalytic amounts of Cinchona alkaloid-derived ureas. These reactions displayed a spectrum of dynamickineticresolution (DKR) and kineticresolution (KR) characters depending upon the stereochemical stability of the starting material. Low barrier substrates proceeded via DKR while higher barrier substrates proceeded via
Combined Computational and Experimental Studies on the Asymmetric Michael Addition of α-Aminomaleimides to β-Nitrostyrenes Using an Organocatalyst Derived from <i>Cinchona</i> Alkaloid
their application as nucleophiles is limited to only a few reactions, and reactions utilizing α-aminomaleimides as asymmetric Michael donors have not been reported to date. Thus, in this work, asymmetric Michaeladdition of α-aminomaleimides as Michael donors to β-nitrostyrenes was conducted for the first time using an organocatalyst derived from a Cinchona alkaloid. Density functional theory investigations
Induction of Axial Chirality in 8-Arylquinolines through Halogenation Reactions Using Bifunctional Organocatalysts
作者:Ryota Miyaji、Keisuke Asano、Seijiro Matsubara
DOI:10.1002/chem.201701707
日期:2017.7.26
The enantioselective syntheses of axially chiral heterobiaryls were accomplished through the aromatic electrophilic halogenation of 3‐(quinolin‐8‐yl)phenols with bifunctional organocatalysts that control the molecular conformations during successive halogenations. Axially chiral quinoline derivatives, which have rarely been synthesized in an enantioselective catalytic manner, were afforded in moderate‐to‐good
A New Family of Cinchona-Derived Bifunctional Asymmetric Phase-Transfer Catalysts: Application to the Enantio- and Diastereoselective Nitro-Mannich Reaction of Amidosulfones
作者:Kayli M. Johnson、Matt S. Rattley、Filippo Sladojevich、David M. Barber、Marta G. Nuñez、Anna M. Goldys、Darren J. Dixon
DOI:10.1021/ol300779x
日期:2012.5.18
family of bifunctional H-bond donor phase-transfer catalysts derived from cinchona alkaloids has been developed and evaluated in the enantio- and diastereoselective nitro-Mannich reaction of in situgenerated N-Boc-protected imines of aliphatic, aromatic, and heteroaromatic aldehydes. Under optimal conditions, good reactivity and high diastereoselectivities (up to 24:1 dr) and enantioselectivities (up to