Abstract
The Friedlander reactions of 4-aminoacridine-3-carbaldehyde with cyclcoalkane-1,2-diones were examined. The reactions of cycloheptane- and cycloocatane-1,2-diones afforded 3,3'-tri- and 3,3'-tetramethylene-2(pyrid-2'-yl)benzo[b]-1,10-phenanthrolines in 20% and 80%, respectively, while reactions with butane-2,3-dione, cyclopentane-1,2-dione and cyclohexane-1,2-dione afforded only unexpected benzo[b]-1,10-phenanthroline. The trimethylene-bridge is flexible at room temperature while the tetramethylene units are rigid enough to magnetically differentiate all the 8 aliphatic protons at room temperature in NMR time scale even though showing two aliphatic carbon resonaces as expected.