Mechanism of the Skraup and Doebner-von Miller quinoline syntheses: Cyclization of. alpha. ,. beta. -unsaturated N-aryliminium salts via 1,3-dizaetidinium ion intermediates

Journal Article · Thu Mar 16 23:00:00 EST 1989 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/jo00267a010· OSTI ID:5053034

Eisch, J J; Dluzniewski, T ^[1]

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1. State Univ. of New York, Binghamton (USA)

The hydrochlorides of cinnamaldehyde anils of the type ArCH=CHCH=NAr{prime}, where Ar and Ar{prime} are phenyl or p-tolyl groups, have been shown to react between 25{degree}C and 100{degree}C, in a toluene suspension or in a solution of DMSO or acetonitrile, to yield 2-substituted quinolines and N-cinnamylanilines ArCH=CHCH{sub 2}NHAr{prime}. The reaction proceeds under anhydrous conditions by cyclization of the anil hydrochlorides themselves to produce ultimately 2-substituted quinolines. The kinetics of the reaction follow a first-order dependence on the anil hydrochloride. Rapid exchange occurring between dissimilar anil hydrochlorides suggests that such anil metatheses take place by way of 1,3-diazetidinium ion intermediates, which previous studies have shown would possess the requisite metastability. The foregoing experimental observations are reconciled in terms of a novel mechanism for the formation of quinolines directly from anils under acidic conditions, namely, the reversible formation of diazetidinium ions and their irreversible cyclization to quinolines. It is proposed that this pathway is the operative mechanism in the classic Skraup and Doehner-von Miller quinoline syntheses. 28 refs., 2 tabs.

• OSTI ID: 5053034
• Journal Information: Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 54:6; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALDEHYDES
AROMATICS
AZAARENES
AZINES
CARBOXYLIC ACIDS
CINNAMIC ACID
DATA
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
KINETICS
MONOCARBOXYLIC ACIDS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIDINES
QUINOLINES
REACTION KINETICS
SYNTHESIS