Application of organolithium in organic synthesis: A simple and convenient procedure for the synthesis of more complex 6-substituted 3H-quinazolin-4-ones

El-Hiti, Gamal A. 2004. Application of organolithium in organic synthesis: A simple and convenient procedure for the synthesis of more complex 6-substituted 3H-quinazolin-4-ones. Monatshefte für Chemie 135 (3) , pp. 323-331. 10.1007/s00706-003-0110-5

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Abstract

6-Methyl-3H-quinazolin-4-one reacts with alkyllithium reagents at 78 0C in THF to give 2-alkyl-1,2-dihydro-6-methyl-3H-quinazolin-4-ones in high yields. However, no reaction took place when LDA was used as the lithium reagent. 6-Bromo-3H-quinazolin-4-one reacts with excess butyllithium to give 2-butyl-1,2-dihydro-3H-quinazolin-4-ones in very good yields. However, the lithiation of 6-bromo-3H-quinazolin-4-one was achieved by the use of a combination of methyllithium (1.1 equivalents) and tert-butyllithium (2.2 equivalents) at –78 0C in THF. The dilithio reagent thus obtained reacts with a variety of electrophiles (H2O, iodoethane, benzaldehyde, anisaldehyde, cyclohexanone, 2-hexanone, benzophenone, phenyl isothiocyanate, TITD) to give the corresponding 6-substituted 3H-quinazolin-4-ones in excellent yields. Reaction of the dilithio reagent with 1,3-dibromopropane gives 6,6-(propanediyl)-bis-3H-quinazolin-4-one.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
Uncontrolled Keywords:	3H-Quinazolin-4-one; Nucleophilic addition; Bromine-lithium exchange; Dilithio reagent; Electrophiles
Publisher:	Springer Verlag
ISSN:	0026-9247
Last Modified:	19 Mar 2016 22:24
URI:	https://orca.cardiff.ac.uk/id/eprint/15363

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