Categories: Synthesis of N-Heterocycles > Lactams
Synthesis of 3,4-dihydro-2-pyridinones
Recent Literature
An N-heterocyclic carbene-catalyzed oxidative LUMO activation of the β-carbons of
saturated carboxylic esters enables an efficient asymmetric access to lactams
and lactones. The method introduces functional groups at the typically inert
β-sp3 carbons of saturated esters. The use of HOBt as an additive
improves both yields and enantioselectivities of the reactions.
B. Liu, W. Wang, R. Huang, J. Yan, J. Wu, W. Xue, S. Yang, Z. Jin, Y. R. Chi, Org. Lett.,
2018, 20, 260-263.
After NHC-catalyzed activation of acetic esters, the catalytically generated
triazolium enolate intermediates serve as two-carbon nucleophiles that undergo
highly enantioselective reactions with enones and α,β-unsaturated imines to give
α-unsubstituted δ-lactones and lactams, respectively.
S. Chen, L. Hao, Y. Zhang, B. Tiwari, Y. R. Chi, Org. Lett., 2013,
15, 5822-5825.
An N-heterocyclic carbene catalyzes a highly enantioselective [3 + 3] annulation
reaction of N-hydroxyphthalimide (NHPI) 3,3-disubstituted acrylates and
N-Ts ketimines, providing the desired chiral dihydropyridinone products bearing
an all carbon quaternary stereogenic center in good yields with excellent
enantioselectivities. The reaction demonstrates that NHPI acrylates are
excellent substrates in NHC-catalysis.
Z. Zhang, X. Zeng, D. Xie, D. Chen, L. Ding, A. Wang, L. Yang, G. Zhong, Org. Lett.,
2015,
17, 5052-5055.