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Quinazolin-4(3H)-ones and 5,6-Dihydropyrimidin-4(3H)-ones from ?-Aminoamides and Orthoesters.


ABSTRACT: Quinazolin-4(3H)-ones have been prepared in one step from 2-aminobenzamides and orthoesters in the presence of acetic acid. Simple 2-aminobenzamides were easily converted to the heterocycles by refluxing in absolute ethanol with 1.5 equivalents of the orthoester and 2 equivalents of acetic acid for 12?24 h. Ring-substituted and hindered 2-aminobenzamides as well as cases incorporating an additional basic nitrogen required pressure tube conditions with 3 equivalents each of the orthoester and acetic acid in ethanol at 110 °C for 12?72 h. The reaction was tolerant towards functionality on the benzamide and a range of structures was accessible. Workup involved removal of the solvent under vacuum and either recrystallization from ethanol or trituration with ether-pentane. Several 5,6-dihydropyrimidin-4(3H)-ones were also prepared from 3-amino-2,2-dimethylpropionamide. All products were characterized by melting point, FT-IR, ¹H-NMR, 13C-NMR, and HRMS.

SUBMITTER: Gavin JT 

PROVIDER: S-EPMC6278269 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Quinazolin-4(3<i>H</i>)-ones and 5,6-Dihydropyrimidin-4(3<i>H</i>)-ones from β-Aminoamides and Orthoesters.

Gavin Joshua T JT   Annor-Gyamfi Joel K JK   Bunce Richard A RA  

Molecules (Basel, Switzerland) 20181109 11


Quinazolin-4(3<i>H</i>)-ones have been prepared in one step from 2-aminobenzamides and orthoesters in the presence of acetic acid. Simple 2-aminobenzamides were easily converted to the heterocycles by refluxing in absolute ethanol with 1.5 equivalents of the orthoester and 2 equivalents of acetic acid for 12⁻24 h. Ring-substituted and hindered 2-aminobenzamides as well as cases incorporating an additional basic nitrogen required pressure tube conditions with 3 equivalents each of the orthoester  ...[more]

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