221071-22-3Relevant academic research and scientific papers
Organocatalytic asymmetric [4+2] cyclization of 2-benzothiazolimines with azlactones: Access to chiral benzothiazolopyrimidine derivatives
Ni, Qijian,Wang, Xuyang,Xu, Fangfang,Chen, Xiaoyun,Song, Xiaoxiao
supporting information, p. 3155 - 3158 (2020/03/23)
An organocatalytic asymmetric domino Mannich/cyclization reaction between 2-benzothiazolimines with azlactones has been successfully developed. With the bifunctional squaramide catalyst, this formal [4+2] cyclization occurs with good to high yields and excellent stereoselectivities (up to 99% ee, >20?:?1 dr), providing an efficient and mild access to chiral benzothiazolopyrimidines bearing adjacent tertiary and quaternary stereogenic centers.
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.
Bifunctional squaramide-catalyzed synthesis of chiral dihydrocoumarins via ortho-quinone methides generated from 2-(1-tosylalkyl)phenols
Zhou, Ji,Wang, Mao-Lin,Gao, Xiang,Jiang, Guo-Fang,Zhou, Yong-Gui
supporting information, p. 3531 - 3534 (2017/03/30)
A bifunctional squaramide-catalyzed reaction of azlactones with o-quinone methides in situ generated from 2-(1-tosylalkyl)-phenols has been successfully developed under basic conditions, providing an efficient and mild access to chiral dihydrocoumarins bearing adjacent tertiary and quaternary stereogenic centers in high yields with excellent diastereo- and enantioselectivities.
Enantioselective synthesis of dihydrocoumarin derivatives by chiral scandium(iii)-complex catalyzed inverse-electron-demand hetero-Diels-Alder reaction
Hu, Haipeng,Liu, Yangbin,Guo, Jing,Lin, Lili,Xu, Yali,Liu, Xiaohua,Feng, Xiaoming
supporting information, p. 3835 - 3837 (2015/03/31)
An asymmetric inverse-electron-demand hetero-Diels-Alder reaction between o-quinone methides and azlactones to generate potentially pharmacological active dihydrocoumarins has been achieved efficiently by using a chiral N,N′-dioxide-Sc(iii) complex as the catalyst. The desired products were obtained in high yields with excellent enantioselectivities and diastereoselectivities (up to 94% yield, 96% ee and >19:1 dr) under mild reaction conditions. A concerted reaction pathway was confirmed by Operando IR and control experiments.
Alkynyliodonium salt mediated alkynylation of azlactones: Fast access to Cα-tetrasubstituted α-amino acid derivatives
Finkbeiner, Peter,Weckenmann, Nicole M.,Nachtsheim, Boris J.
supporting information, p. 1326 - 1329 (2014/04/03)
An efficient electrophilic alkynylation of azlactones (oxazol-5(4H)-ones) is developed using alkynyl(phenyl)iodonium salts as the electrophilic alkyne source. After remarkably short reaction times, the desired alkyne functionalized azlactones are obtained in 60-97% yield and can be transformed easily into a variety of quaternary α-amino acid derivatives.
Design and synthesis of 3-arylpyrrolidine-2-carboxamide derivatives as melanocortin-4 receptor ligands
Tran, Joe A.,Tucci, Fabio C.,Arellano, Melissa,Jiang, Wanlong,Chen, Caroline W.,Marinkovic, Dragan,Fleck, Beth A.,Wen, Jenny,Foster, Alan C.,Chen, Chen
, p. 1931 - 1938 (2008/09/20)
Based on 3-phenylpropionamides, a series of 3-arylpyrrolidine-2-carboxamide derivatives was designed and synthesized to study the effect of cyclizations as melanocortin-4 receptor ligands. It was found that the 2R,3R-pyrrolidine isomer possessed the most
Ring opening with kinetic resolution of azlactones by Ti-TADDOLates
Gottwald, Konstanze,Seebach, Dieter
, p. 723 - 738 (2007/10/03)
The kinetic resolution of azlactones by the Lewis, acid-mediated transfer of an isopropoxide ligand from the chiral ligand sphere of Ti- TADDOLate is described. The reactions proceed with in-situ racemization of the starting material to afford highly enantiomerically enriched N-benzoyl- amino acid isopropylesters (er > 95:5 after recrystallization). The absolute configuration of the major enantiomer of N-benzoyl-phenylalanine isopropyl ester and its analogs with other aromatic substituents was shown to be (S)- (+) when the (R,R)-Ti-TADDOLate was employed. Only benzyl-substituted azlactones can be opened enantioselectively by the method described here.
