71963-73-0Relevant articles and documents
Asymmetric Aza-Diels-Alder Reactions of in Situ Generated β,β-Disubstituted α,β-Unsaturated N-H Ketimines Catalyzed by Chiral Phosphoric Acids
He, Shunlong,Gu, Huanchao,He, Yu-Peng,Yang, Xiaoyu
supporting information, p. 5633 - 5639 (2020/07/14)
A novel asymmetric synthesis of dihydropyridinones with vicinal quaternary stereocenters has been realized by asymmetric aza-Diels-Alder reactions of 3-amido allylic alcohols with oxazolones enabled by chiral phosphoric acid catalysis. A series of aryl/alkyl- and alkyl/alkyl-disubstituted 3-amido allylic tertiary alcohols and 4-substituted oxazolones could be well tolerated in these reactions, producing dihydropyridinones with excellent diastereoselectivities and high enantioselectivities. Mechanistic study and control experiments were performed to shed light on the reaction mechanism, in which a configurationally defined β,β-disubstituted α,β-unsaturated N-H ketimine was proposed as the key intermediate.
Asymmetric construction of dihydrobenzofuran-2,5-dione derivatives via desymmetrization of p-quinols with azlactones
Xie, Lihua,Dong, Shunxi,Zhang, Qian,Feng, Xiaoming,Liu, Xiaohua
supporting information, p. 87 - 90 (2019/01/03)
The desymmetrization of p-quinols through a chiral bisguanidinium hemisalt catalyzed enantioselective Michael addition/lactonization cascade reaction with azlactones was reported. 3-Amino-benzofuran-2,5-diones containing a chiral amino acid residue were achieved with up to 99% ee and >19?:?1 dr. An exploration of the structure of the catalyst bisguanidinium was undertaken, revealing a bifunctional catalytic model.
Metal-Free Insertion Reactions of Diazo Carbonyls to Azlactones
De Mello, Amanda C.,Momo, Patrícia B.,Burtoloso, Antonio C. B.,Amarante, Giovanni W.
, p. 11399 - 11406 (2018/09/12)
Insertion reactions of diazo carbonyls to azlactones in basic conditions have been performed. The developed method allows the preparation of a wide range of oxazole derivatives in yields ranging from 74 to 98%. Different substituents on both azlactone rings and diazo carbonyls do not compromise the methodology, even those containing stereogenic centers. Isotopic labeling experiments revealed the mechanism may proceed through a rare diazo carbonyl activation by an ammonium salt derivative.
