Solvent directed chemically divergent synthesis of β-lactams and α-amino acid derivatives with chiral isothiourea |
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| Authors: | Dong-Sheng Ji Hui Liang Kai-Xuan Yang Zhi-Tao Feng Yong-Chun Luo Guo-Qiang Xu Yucheng Gu Peng-Fei Xu |
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| Institution: | State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 P. R. China.; State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou 730000 P. R. China ; Department of Chemistry, University of California Davis, One Shields Avenue, Davis California 95616 USA ; Syngenta Jealott''s Hill International Research Centre, Bracknell Berkshire RG42 6EY UK |
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| Abstract: | A protocol for the chemically divergent synthesis of β-lactams and α-amino acid derivatives with isothiourea (ITU) catalysis by switching solvents was developed. The stereospecific Mannich reaction occurring between imine and C(1)-ammonium enolate generated zwitterionic intermediates, which underwent intramolecular lactamization and afforded β-lactam derivatives when DCM and CH3CN were used as solvents. However, when EtOH was used as the solvent, the intermediates underwent an intermolecular esterification reaction, and α-amino acid derivatives were produced. Detailed mechanistic experiments were conducted to prove that these two kinds of products came from the same intermediates. Furthermore, chemically diversified transformations of β-lactam and α-amino acid derivatives were achieved.A protocol for the solvent directed chemically divergent synthesis of β-lactam and α-amino acid derivatives with chiral isothiourea was reported. |
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