Synthesis of 1,8-naphthyridines and related compounds
TABO (1,3,3-trimethyl-6-azabicyclo[3.2.1]octane) is a a highly reactive and regioselective catalyst for the preparation of 2-substituted quinolines, 1,8-naphthyridines, and chromone derivatives from unmodified methyl ketones and o-aminoaromatic aldehydes. Regioselectivity increased with slow addition of the methyl ketone substrate to the reaction mixture.
M. Movassaghi, M. D. Hill, J. Am. Chem. Soc., 2006, 128, 4592-4593.
A novel copper-catalyzed [5 + 1] annulation of 2-ethynylanilines with an N,O-acetal gives quinoline derivatives with an ester substituent on the 2-position. A combination of CuBr2 and trifluoroacetic acid (TFA) promotes a [5 + 1] annulation of 2-ethynylaniline with ethyl glyoxylatein the presence of piperidine.
N. Sakai, K. Tamura, K. Shimamura, R. Ikeda, T. Konakahara, Org. Lett., 2012, 14, 836-839.
A single-step, facile synthesis of 1,8-naphthyridine derivatives in good yields was carried out at room temperature under mild conditions using a three-component condensation reaction of substituted 2-aminopyridines, malononitrile or methyl/ethyl cyanoacetate, and various aldehydes in the presence of a N-bromosulfonamide as Lewis acid.
R. Ghorbani-Vaghei, S. M. Malaekehpoor, Synthesis, 2017, 49, 763-769.