Beilstein J. Org. Chem.2016,12, 444–461, doi:10.3762/bjoc.12.47
chirally pure α-amino ketones formed in this reaction are valuable building blocks in organic synthesis [37].
The NHC generated from the bicyclic pentafluoro triazolium salt promoted the chemoselective cross aza-benzoin reaction of aldehydes with N-PMP-imino esters to afford α-amino-β-ketoesters in good
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Graphical Abstract
Scheme 1:
Breslow’s proposal on the mechanism of the benzoin condensation.
Beilstein J. Org. Chem.2012,8, 1499–1504, doi:10.3762/bjoc.8.169
Takuya Uno Yusuke Kobayashi Yoshiji Takemoto Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan 10.3762/bjoc.8.169 Abstract An efficient catalytic synthesis of α-amino-β-ketoesters has been newly developed. Cross-coupling of various aldehydes
with α-imino ester, catalyzed by N-heterocyclic carbene, leads chemoselectively to α-amino-β-ketoesters in moderate to good yields with high atom efficiency. The reaction mechanism is discussed, and it is proposed that the α-amino-β-ketoesters are formed under thermodynamic control.
Keywords: α
of PhI=O is needed as the oxidant (Figure 1, (e)) [23]. Therefore, mild, efficient and environmentally friendly strategies for the synthesis of these esters are still needed. We envisioned that highly atom-efficient synthesis of α-amino-β-ketoesters could be achieved by a novel umpolung approach
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Graphical Abstract
Figure 1:
Synthetic methods for α-amino-β-keto esters.