54049-21-7Relevant academic research and scientific papers
Asymmetric Synthesis of 2H-Azirines with a Tetrasubstituted Stereocenter by Enantioselective Ring Contraction of Isoxazoles
Okamoto, Kazuhiro,Nanya, Atsushi,Eguchi, Akira,Ohe, Kouichi
, p. 1039 - 1043 (2018/01/26)
Highly strained 2H-azirines with a tetrasubstituted stereocenter were synthesized by the enantioselective isomerization of isoxazoles with a chiral diene–rhodium catalyst system. The effect of ligands and the coordination behavior support the proposed cat
Rhodium-catalyzed asymmetric hydrogenation through dynamic kinetic resolution: asymmetric synthesis of anti-β-hydroxy-α-amino acid esters
Makino, Kazuishi,Fujii, Takefumi,Hamada, Yasumasa
, p. 481 - 485 (2007/10/03)
Rhodium-catalyzed asymmetric hydrogenation of α-amino-β-keto ester hydrochlorides through dynamic kinetic resolution is described. The hydrogenation proceeds with the catalyst derived from a Rh complex and a chiral ferrocenylphosphine under hydrogen in th
Asymmetric Syntheses via Heterocyclic Intermediates, XL. - Studies on the Acylation of Lithiated Bislactim Ethers of cyclo(-L-Val-Ala-) and cyclo(-L-Val-Gly-). - Asymmetric Synthesis of (R)-α-Alkenyl and (R)-α-Ethinyl Alanine Methyl Esters by the Bislactim Ether Method
Schoellkopf, Ulrich,Westphalen, Karl-Otto,Schroeder, Juergen,Horn, Klaus
, p. 781 - 786 (2007/10/02)
The lithiated bislactim ether 2a of cyclo(-L-Val-Ala-) reacts with acyl chlorides 3 highly diastereoselectively to yield the compounds 4 with (2S,5S)-configuration.With acetyl chloride (3a) the N-acetyl compound 7 is formed as a sideproduct.Alternatively, the compounds 4 can be obtained by oxidation of the carbinols 8.From 4a and b, the olefins 11a and b are obtained by Wittig reaction.These are precursors of methyl (R)-α-alkenyl alanine methyl esters of type 13. (R)-α-ethinyl alanine methyl ester 17 is obtainable from 4a and 4e via the intermediates 14 or 15 and16a.The lithiated bislactim ether 2c of cyclo(-L-Val-Gly-) reacts with benzoyl chloride (3b) to give the "bis adduct" 18.However, 6b is obtained from 2c and the benzamide 19, though as a 1:1 diastereomeric mixture.Presumably, 6b epimerizes via the enol 21a subsequently to its diastereoselective formation.
