Synthesis of Enamines and related compounds
Arylations of electron-rich heteroatom-substituted olefins were performed with electron-rich arylboronic acids via palladium(II) catalysis. This mild protocol, which offers access to functionalized enamides, exploits oxygen gas for reoxidation and a stable 1,10-phenanthroline bidentate ligand to promote the palladium(II) regeneration and to control the regioselectivity.
M. M. S. Andappan, P. Nilsson, H. v. Schenck, M. Larhed, J. Org. Chem., 2004, 69, 5212-5218.
A highly efficient and stereoselective arylation of in situ-generated azavinyl carbenes affords 2,2-diaryl enamines at ambient temperatures. These transition-metal carbenes are directly produced from readily available and stable 1-sulfonyl-1,2,3-triazoles in the presence of a rhodium carboxylate catalyst. In several cases, the enamines can be cyclized into substituted indoles employing copper catalysis.
N. Selander, B. T. Worrell, S. Chuprakov, S. Velaparthi, V. V. Fokin, J. Am. Chem. Soc., 2012, 134, 14670-14673.
An earth-abundant iron catalyst enables a dehydrogenative acylation of enamides with aldehydes to provide valuable β-ketoenamides with excellent functional group tolerance. The C-H acylation occurs with absolute Z-selectivity.
R.-H. Liu, Z.-Y. Shen, C. Wang, T.-P. Loh, X.-H. Hu, Org. Lett., 2020, 22, 944-949.
A Rh(III)-catalyzed protocol for the amidation of anilide and enamide C-H bonds with isocyanates provides direct and efficient syntheses of N-acyl anthranilamides, enamine amides, and pyrimidin-4-one heterocycles.
K. D. Hesp, R. G. Bergman, J. A. Ellman, J. Am. Chem. Soc., 2011, 133, 11430-11433.
An efficient, mild, and general method for the C-arylation of β-enamino esters and ketones with arynes provides a facile and direct access to various substituted aromatic β-enamino compounds in good yield.
Y. K. Ramtohul, A. Chartrand, Org. Lett., 2007, 9, 1029-1032.