Mechanism of Akaline Cyclization of 2- (Substitution Benzamido)Benzamides to 4-Quinazolinones

Gardner, Barry and Kanagasooriam, Angeline J S S and Smyth, Richard M. and Williams, Andrew (1994) Mechanism of Akaline Cyclization of 2- (Substitution Benzamido)Benzamides to 4-Quinazolinones. Journal of Organic Chemistry, 59 (21). pp. 6245-6250. ISSN 0022-3263. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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The title amides cyclize rapidly to the corresponding quinazolin-4-ones in aqueous alkaline solution at 25 degrees C; the pseudo-first-order rate constants fit the empirical equation k(obs) = k(max) [OH-]/K-m + [OH-] + [OH-]K-2(m')) where K-m' is essentially zero for all except the 4-nitro species. The value of K-m measures the ionization of the neutral amide 1 to nonproductive conjugate base 2. Studies of the cyclization in alkali of 2-benzamido-N-methylbenzamide (1i) and 2-(N-methylbenzamido)benzamide (1j) indicate that 7 carries over 99% of the reaction flux and that the tautomer 8 does not contribute significantly. The ratio k(max)/K-m, is a composite rate constant first order in 1 and first order in [OH-]. The value of the Hammett rho for k(max)/K-m (0.67) is consistent with the above scheme where decomposition of 7 is rate limiting.

Item Type: Article
Subjects: Q Science > QD Chemistry
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: P. Ogbuji
Date Deposited: 26 Jun 2009 17:26
Last Modified: 01 May 2014 11:48
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