Imidazo[1,2-a]quinoxalines: synthesis and cyclic nucleotide phosphodiesterase inhibitory activity
摘要:
A group of imidazo[1,2-a]quinoxalines have been synthesised from quinoxaline by condensation of an appropriate haloester or intramolecular cyclisation of a keto moiety on an intracyclic nitrogen atom. The reactivity of the heterocycle was explored through diverse reactions such as electrophilic substitution, lithiation and halogen-metal exchange to give access to a new series of derivatives. Confirmation of their structure was mainly performed by NMR, after careful assignment of the signals in comparison to previous attributions made on the parent imidazo[1,2-a]quinoxaline and discussion of available data in the literature. The cyclic nucleotide phosphodiesterase inhibitor activity of some of these derivatives has been assessed on isoenzymes type III and type IV. Compound 15, 4-(methylamino)imidazo[1,2-a]quinoxaline-2-carbonitrile, exhibited potent relaxant activity on smooth muscle, with a potency similar to the one measured with SCA 40, its structural analogue in the imidazo[1,2-a]pyrazine series. (C) 2001 Editions scientifiques et medicales Elsevier SAS.
Metalation and halogen-metal exchange in the imidazo[1,2-<i>a</i>]quinoxaline series
作者:Stéphanie Parra、Olivier Vitse、Véronique Bénézech、Carine Deleuze-Masquéfa、Guy Subra、Jacques Bompart、Roger Escale、Jean P. Chapat、Pierre A. Bonnet
DOI:10.1002/jhet.5570380106
日期:2001.1
The n-butyllithium and lithium 2,2,6,6-tetramethylpiperidide metalation and the halogen-metal exchange of imidazo[1,2-a]quinoxaline derivatives followed by quenching with various electrophiles were studied. The reaction conditions have been optimized and various C1 substituted imidazo[1,2-a]quinoxalines were obtained in high yields.