74415-34-2Relevant academic research and scientific papers
A NOVEL REGIOSPECIFIC INTRAMOLECULAR CYCLOADDITION OF AN AROMATIC RING. MOLECULAR ORBITAL STUDY OF CONJUGATED KETENES THERMALLY GENERATED FROM SIX-MEMBERED α-MONOCARBONYL AZO-COMPOUNDS
Kuzuya, Masayuki,Miyake, Fumio,Okuda, Takachiyo
, p. 1471 - 1478 (2007/10/02)
When a methylene dichloride solution containing 4,4-diarylphthalazin-1(4H)-one (3) was warmed above -50 deg C, nitrogen extrusion occurred to result in the formation of the quinonoid ketene (19).The quinonoid ketene thus generated underwent a facile and regiospecific intramolecular ?4a + ?2a> cycloaddition with NN-dimethylaniline to afford a norcaradiene (22), followed by ring opening to an azulenone derivative (14).It was found, however, that this process takes place only with an aromatic ring bearing strong electron-donating substituents such as dialkylamino groups.FMO analyses based on the model system calculated by the CNDO/2 method showed that the dominant HOMO-LUMO interaction in the transition state should involve the HOMO of NN-dialkylaniline and LUMO of the quinonoid ketene.Thus, the in-plane ?*-orbital induces the orthogonal approach of the two components favouring an antarafacial pathway and the cyclisation is initiated by preferential bond formation between the central carbon of the ketene moiety and the para-carbon of NN-dialkylaniline to result in the formation of (22).
Antarafacial role of an aromatic nucleus; a novel regiospecific [π4a + π2a] intramolecular cycloaddition of the ene-ketene with an aromatic ring
Kuzuya, Masayuki,Miyake, Fumio,Okuda, Takachiyo
, p. 1043 - 1046 (2007/10/02)
The thermally generated ene-ketene undergoes a facile and regiospecific intramolecular cycloaddition with N,N-dimethylaniline to result in the novel formation of the azulenone derivative via a norcaradiene intermediate.
