Theoretical investigation of direct amination of beta-ketoesters catalyzed by copper(II)-bisoxazoline(BOX).
The mechanism of the direct amination of beta-keto esters catalyzed by copper(II)-bisoxazoline has been studied by means of density functional theory of B3LYP method. The computational results support the present mechanism, which involves (i) the generation of the enol from beta-keto esters, which coordinates to copper(II)-bisoxazoline. The coordination step appears to be fast, exothermic, and irreversible. (ii) The formation of the sigma(N-C) bond via a six-membered ring transition state after azo dicarboxylate coordination with the chiral catalyst. This step is chirality-control step. (iii) Intramolecular hydrogen migration generates a catalyst-product complex, which can finally yield product. The hydrogen shift is the rate-determining step, which affords the experimentally observed (R)-product. The stereochemical predictions have been rationalized in terms of steric repulsions, showing good agreement with experimental data.
Yu
Youqing
Y
Department of Chemistry, Southwest University, Chongqing, 400715, People's Republic of China.
Shen
Wei
W
Zhang
Jinsheng
J
He
Rongxing
R
Li
Ming
M
D000586:Amination; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D004952:Esters / Q000737:chemistry*; D008956:Models, Chemical; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry*; D011522:Protons; D012997:Solvents; D013237:Stereoisomerism; D013816:Thermodynamics
D004952:Esters; D009942:Organometallic Compounds; D010080:Oxazoles; D011522:Protons; D012997:Solvents; D003300:Copper