The unambiguous synthesis of 1,6-dichloro-3-ethylindeno[1,2,3-de]quinolin-2(3H)-one (7) was undertaken. Product 7 was found to be identical with that derived by sulfuric acid catalyzed cyclization of 2,2,4′-trichloro-N-ethylbenzoylacetanilide (4). This is evidence that 7 arises from 4 via a "direct" cyclization intermediate. A convenient modification of the Cook and Koelsch indenoquinolinone synthesis, which afforded 7 by a shorter route, is reported. The diagnostically useful anisotropic deshielding of the C-7 and C-10 protons by the halogen at C-1 and C-6 in the 1H NMR spectrum of 7 is described.
|Number of pages||4|
|Journal||Journal of Organic Chemistry|
|Publication status||Published - 1977|