Quinine-Based Trifunctional Organocatalyst for Tandem Aza-Henry Reaction-Cyclization: Asymmetric Synthesis of Spiroxindole-Pyrrolidine/Piperidines
作者:Saumen Hajra、Bibekananda Jana
DOI:10.1021/acs.orglett.7b02150
日期:2017.9.15
A quinine-derived trifunctional sulphonamide catalyst has been developed for the effective asymmetric organocatalytic tandem aza-Henry reaction-cyclization of isatin-derived ketimines and nitroalkane-mesylates for the synthesis of spiro-pyrrolidine/piperidine-oxindoles. Demethylation of traditional bifunctional catalyst to incorporate an additional hydrogen bonding C6′–OH group plays the key role toward
An enantioselective one-pot aldol/lactonization sequence has been developed to access highly challenging γ-butyrolactones bearing an all-carbonquaternarystereocenter at the β-position by reacting acylated succinic esters with aqueous formaldehyde in the presence of 3 mol % loading of a cinchona alkaloid-derived squaramide providing direct access to paraconic acid derivatives in high yield and fairly
Catalytic asymmetric cycloetherification via intramolecular oxy-Michael addition of enols
作者:Ryuichi Murata、Keisuke Asano、Seijiro Matsubara
DOI:10.1016/j.tet.2021.132381
日期:2021.9
compounds as oxygen nucleophiles. In particular, there are only a few reports on the oxy-Michael addition of the enol forms of carbonyl nucleophiles. In this study, we present the asymmetric cycloetherification of enols, which are generated in situ from enone-bearing ketones, using chiralbifunctionalorganocatalysts bearing amino and squaramide groups. This transformation chemo- and enantioselectively afforded
Catalytic Asymmetric Synthesis of Quaternary Barbituric Acids
作者:Sandra del Pozo、Silvia Vera、Mikel Oiarbide、Claudio Palomo
DOI:10.1021/jacs.7b09124
日期:2017.11.1
The catalytic asymmetric α-functionalization of prochiral barbituricacids, a subtype of pseudosymmetric 1,3-diamides, to yield the corresponding 5,5-disubstituted (quaternary) derivatives remains essentially unsolved. In this study 2-alkylthio-4,6-dioxopirimidines are designed as key 1,3-diamide surrogates that perform exceedingly in amine-squaramide catalyzed C-C bond forming reactions with vinyl
前手性巴比妥酸(假对称 1,3-二酰胺的一种亚型)的催化不对称 α-官能化产生相应的 5,5-二取代(季)衍生物基本上仍未解决。在这项研究中,2-烷硫基-4,6-二氧嘧啶被设计为关键的 1,3-二酰胺替代物,在胺-方酸酰胺催化的 CC 键形成反应中表现出色,乙烯基酮或 Morita-Baylis-Hillmann 型烯丙基溴作为亲电子试剂。加合物的温和酸水解以前所未有的对映选择性提供具有环内季碳的巴比妥酸衍生物,为生物学评估提供有价值的材料。
Highly Enantioselective Michael Addition of Nitroalkanes to Chalcones Using Chiral Squaramides as Hydrogen Bonding Organocatalysts
作者:Wen Yang、Da-Ming Du
DOI:10.1021/ol102294g
日期:2010.12.3
squaramide-based organocatalysts were facilely synthesized and applied as hydrogen bonding organocatalysts in the enantioselectiveMichaeladdition of nitroalkanes to chalcones. These organocatalysts promoted the Michaeladdition with low catalyst loading under high temperature (80 °C), affording the desired R or S enantiomers of the products flexibly in high yields with excellent enantioselectivities (93−96%