Synthesis of ε-lactams
Lewis acid-promoted reactions of alkyl azides with ketones can afford several products. Cyclohexanones and other cyclic ketones react in the presence of TiCl4 to afford Schmidt-like insertion products, whereas an acid-promoted rearrangement of the azide to an iminium species can occur, mostly with benzylic azides and TfOH; the iminium species can then be trapped by enolates.
P. Desai, K. Schildknegt, K. A. Agrios, C. Mossman, C. Mossman, G. L. Milligan, J. Aubé, J. Am. Chem. Soc., 2000, 122, 7226-7232.
An oxidative copper-catalyzed arylation of various ring-size lactams with arylboronic acids gives N-arylated products in good yield without any additional bases, ligands, or additives.
T. Bathini, V. S. Rawat, B. Sreedhar, Synlett, 2015, 26, 1348-1351.
A quick, efficient, one-pot, BF3ˇOEt2-mediated reaction of various substituted arenes with azido alkanoic acid chlorides affords substituted N-aryl lactams in good to excellent yields at room temperature.
D. Caturvedi, A. K. Chaturvedi, N. Mishra, V. Mishra, Synlett, 2012, 23, 2627-2630.
In a metal-free, selective oxidation of cyclic secondary and tertiary amines for the formation of lactams, molecular iodine facilitates both chemoselective and regioselective oxidation of C-H bonds directly adjacent to a cyclic amine. The reaction offers mild conditions, functional group tolerance, and a broad substrate scope.
R. J. Griffiths, G. A. Burley, E. P. A. Talbot, Org. Lett., 2017, 19, 870-873.