Sterically controlled synthesis of optically active organic compounds. V. Sterically controlled synthesis of optically active .alpha.-amino acids from .alpha.-oxo acids by reductive amination
Selective amidation by a photocatalyzed umpolung reaction
作者:Debasish Ghosh、Rajesh Nandi、Saikat Khamarui、Sukla Ghosh、Dilip K. Maiti
DOI:10.1039/c9cc01079c
日期:——
Herein, a metal-catalyzed organic transformation merged with another organophotocatalyst has been developed under mild conditions for the production of α-ketoamides.
A novel approach for the one-pot preparation of α-ketoamides by anodic oxidation
作者:Zhenlei Zhang、Jihu Su、Zhenggen Zha、Zhiyong Wang
DOI:10.1039/c3cc43685c
日期:——
The direct oxidative synthesis of α-ketoamides via anodic oxidation was developed by using dioxygen as a reactant under mild conditions. This methodology has a broad substrate scope (aromatic amines, aliphatic amines and ammonium acetate) and opens up an interesting and attractive avenue for the synthesis of α-ketoamide derivatives.
Chemistry of novel compounds with multifunctional carbon structure. 9. Molecular design, synthetic studies, and NMR investigation of several efficient chiral derivatizing reagents which give very large 19F NMR .DELTA..delta. values in enantiomeric excess determination
In order to develop efficient ee-determining reagents potentially superior to MTPA (1), some multifunctional compounds 2-5 were rationally designed. From NMR investigations of the analogous diastereomeric derivatives it was found that the chemical shift differences for each pair of diastereomers (DELTAdelta values) for CFPA derivatives 5d-f were approximately five times greater in F-19 NMR spectra and two times greater in H-1 NMR spectra than those of 1d-f. Synthesis of the optically pure CFPA, (-)-5a and (+)-5a, was achieved by nitrosation of each diastereomer of the optically active N-(1-phenylethyl)amides, 5f(M) and 5f(L), followed by thermal decomposition. Various derivatives were prepared by the condensation of 5b and lb with alcohol and amine nucleophiles, and both DELTAdelta(F) and DELTAdelta(H) Values were obtained for each compound. The CFPA derivatives 5d-m have proven to be significantly superior for ee determinations when compared to the corresponding MTPA derivatives 1d-m, particularly in compounds having remotely disposed chiral centers.
Diastereoselective reduction and carboncarbon bond formation of α-keto esters/amides with SmI2
The stereoselective reduction of alpha -keto esters/alpha -keto amides, which have various chiral auxiliaries using SmI2, is examined. 2(S)-Methoxymethylpyrrolidine, 1,1,2(S)- and 1,1,2(R)-triphenylethanediol were found to be suitable chiral auxiliaries that produced the corresponding alpha -hydroxy ester and amide in good diastereoselectivity with satisfactory yields. Allylation, the Reformatsky-type reaction, and the ketyl-alkene coupling reaction with the 1,1,2(R)-triphenylethanediol and 2(S)-methoxymethylpyrrolidine, derivative of the alpha -keto ester/amide proceeded smoothly with high diastereoselectivity. (C) 2001 Elsevier Science Ltd. All rights reserved.
TAKEUCHI, YOSHIO;ITOH, NORIAKI;NOTE, HIROSHI;KOIZUMI, TORU;YAMAGUCHI, KEN+, J. AMER. CHEM. SOC., 113,(1991) N6, C. 6318-6320