A convenient procedure for the synthesis of novel modified 3 substituted 1H-quinoxaline-2-thiones via side-chain lithiation of 3-alkyl-1H-quinoxaline-2-thiones

El-Hiti, Gamal A. 2003. A convenient procedure for the synthesis of novel modified 3 substituted 1H-quinoxaline-2-thiones via side-chain lithiation of 3-alkyl-1H-quinoxaline-2-thiones. Synthesis (Stuttgart) (18) , pp. 2799-2804. 10.1055/s-2003-42486

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Abstract

3-Methyl-1H-quinoxaline-2-thione (1) has been doubly lithiated, at nitrogen and at the 3-methyl group, with n-butyllithium at –78 °C in THF. The resulting dilithium reagent obtained reacts with a variety of electrophiles (iodomethane, iodoethane, 1-bromobutane, D2O, benzaldehyde, anisaldehyde, 2-hexanone, cyclohexanone, benzophenone, phenyl isothiocyanate) to give the corresponding modified 3-substituted 1H-quinoxaline-2-thiones 4–13 in high yields. Similarly, double lithiation of 3-ethyl- (4) and 3-propyl-1H-quinoxaline-2-thiones (5), followed by reaction with some electrophiles gave the corresponding modified 3-substituted derivatives 15–19 in high yields. Treatment of some of the products with trifluoroacetic acid in dichloromethane at room temperature led to formation of substituted 2,3-dihydrothieno[2,3-b]quinoxalines in good yields.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Chemistry
Subjects:	Q Science > QD Chemistry
Uncontrolled Keywords:	quinoxalines ; lithiation ; electrophilic additions ; cyclizations ;heterocycles ; sulfur
Publisher:	Georg Thieme Verlag
ISSN:	0039-7881
Last Modified:	19 Mar 2016 22:25
URI:	https://orca.cardiff.ac.uk/id/eprint/15608

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