Categories: Synthesis of N-Heterocycles >
Synthesis of 1,2,3,4-tetrahydropyridines
In situ transformation of a metathesis active Ru-carbene into an isomerization active Ru-hydride catalyst by addition of hydroxide as a chemical trigger enables the conversion of N-Allyl-N-homoallylamines in one step into cyclic enamides via a tandem catalytic ring-closing metathesis-isomerization sequence.
B. Schmidt, S. Hauke, N. Mühlenberg, Synthesis, 2014, 46, 1648-1658.
A palladium-catalyzed cyclization-Heck reaction of allenamides enables an efficient one-pot construction of functionalized 3-methylene-5-aryl-1,2,3,4-tetrahydropyridines. These compounds feature a nonconjugated diene, including one endo-enamine and one exocyclic double bond, which could be used for further transformation.
F. Yan, H. Liang, J. Song, J. Cui, Q. Liu, S. Liu, P. Wang, Y. Dong, H. Liu, Org. Lett., 2017, 19, 86-89.
Cascade reactions of saturated cyclic amines with 2-oxo-2-arylacetic acids enable a highly regioselective and versatile synthesis of acylated N-heterocycles. In this cascade process, the copper catalyst is believed to play a crucial role not only in dehydrogenation but also in the decarboxylation and cross coupling reaction.
X. Shi, X. Chen, M. Wang, X. Zhang, X. Fan, J. Org. Chem., 2018, 83, 6524-6533.
An efficient chiral Lewis acid-catalyzed inverse-electron-demand Diels-Alder reaction of N-sulfonyl 1-aza-1,3-dienes is based on the combination of Ni(II)-DBFOX complex as catalyst and the use of a metal-coordinating (8-quinolyl)sulfonyl moiety. The reaction provides highly functionalized piperidine derivatives in good yields with excellent endo-selectivity, and good enantioselectivities.
J. Esquivias, R. G. Arrays, J. C. Carretero, J. Am. Chem. Soc., 2007, 129, 1480-1481.