Synthesis 2004(3): 363-368  
DOI: 10.1055/s-2004-815923
PAPER
© Georg Thieme Verlag Stuttgart · New York

A Simple Procedure for the Side-Chain Substitution of 2-Alkyl-3H-quinazo­line-4-thiones: Application in Synthesis

Gamal A. El-Hiti*Centre for Clean Chemistry, Department of Chemistry, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK
Fax: +44(1792)295747; e-Mail: g.a.el-hiti@swansea.ac.uk;
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Publication History

Received 12 November 2003
Publication Date:
26 January 2004 (eFirst)

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Abstract

Double lithiation of 2-alkyl-3H-quinazoline-4-thiones at nitrogen and at the α-hydrogen of the 2-alkyl group (Me, Et, Pr) has been achieved with n-butyllithium at -78 °C in anhydrous THF under nitrogen. Reactions of the dilithium reagents obtained with various electrophiles (iodomethane, iodoethane, 1-bromobutane, D2O, benzaldehyde, 4-anisaldehyde, butan-2-one, cyclohexanone, benzophenone, phenyl isothiocyanate, tetraisopropylthiuram disulfide) gave the corresponding modified 2-substituted 3H-quinazoline-4-thiones 4-22 in excellent yields.

Key words

3H-quinazoline-4-thiones - lithiation - organolithiums - electrophiles