Introduction of Benzo[h]quinoline and 1,10-Phenanthroline Subunits by Friedländer Methodology

An improved preparation of 8-amino-7-quinolinecarbaldehyde has been developed. The methyl group of 7-methyl-8-nitroquinoline may be oxidized to an aldehyde by treatment first with dimethylformamide dimethyl acetal followed by sodium periodate. Reduction with iron provides the amino aldehyde. An analogous sequence affords 1-amino-2-naphthalenecarbaldehyde. Friedländer condensation of the quinoline derivative with a series of acetylaromatics provides the corresponding 2-aryl-1,10-phenanthrolines. Condensation of either amino aldehyde with 1,3-diacetylbenzene or 2,6-diacetylpyridine provides the expected Friedländer product. Similar chemistry is described for reactions of the amino aldehydes with 1,4-diacetylbenzene, 4,4'-diacetylbiphenyl, 1,5-diacetylanthracene, 1,2,3,4,5,6,7,8-octahydroacridine-1,8-dione, and tetracyclo[6.3.0.0.(4,11)0(5,9)]undecane-2,7-dione (TCU-2,7-dione).