Dynamic Kinetic Resolution of Azlactones by a Chiral <i>N</i>,<i>N</i>-Dimethyl-4-aminopyridine Derivative Containing a 1,1′-Binaphthyl Unit: Importance of Amide Groups
作者:Hiroki Mandai、Kohei Hongo、Takuma Fujiwara、Kazuki Fujii、Koichi Mitsudo、Seiji Suga
DOI:10.1021/acs.orglett.8b01960
日期:2018.8.17
resolution (DKR) of azlactones in the presence of benzoic acid and a binaphthyl-based N,N-4-dimethylaminopyridine (DMAP) derivative 1i having two amide groups at the 3,3′-positions of a binaphthyl unit is developed. The reaction proceeded smoothly with a wide range of azlactones to provide α-amino acid derivatives with good to high enantiomeric ratios (er’s). A multigram-scale reaction (2.5 g) for the
Dynamic Kinetic Resolution of Azlactones by Bifunctional Thioureas with α‑Trifluoromethyl or Methyl Groups
作者:Marcos Hernández-Rodríguez、Eddy I. Jiménez、Margarita Cantú-Reyes、Miguel Flores-Ramos、Carlos A. Román-Chavarría、Howard Díaz-Salazar
DOI:10.1055/a-1892-9911
日期:2022.10
The asymmetric ring opening of azlactones via dynamickineticresolution (DKR) is investigated by contrasting thioureas incorporating 1-arylethyl substituents against their more acidic trifluoromethylated analogs. All the catalysts under study outperform Takemoto’s thiourea because of the inclusion of an additional chiral center. However, the difference in yield and selectivity between the fluorinated
Fast Amide Couplings in Water: Extraction, Column Chromatography, and Crystallization Not Required
作者:Sudripet Sharma、Nicklas W. Buchbinder、Wilfried M. Braje、Sachin Handa
DOI:10.1021/acs.orglett.0c01676
日期:2020.8.7
In the micelle of PS-750-M, the presence of 3 degrees amides from the surfactant proline linker mimics dimethylforma-mide, dimethylacetamide, and N-methyl-2-pyrrolidone. The resultant micellar properties enable extremely fast amide couplings mediated by 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide (without hydroxybenzotriazole), rather than expensive and specialized coupling agents. Conditions have been developed wherein products precipitate, and isolation by filtration completely avoids the use of organic solvent. This methodology is scalable and avoids product epimerization.