ChemInform Abstract: Multicomponent Access to Functionalized Mesoionic Structures Based on TFAA Activation of Isocyanides: Novel Domino Reactions (original) (raw)
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In recent years, organic donor-acceptor complexes have attracted much attention, leading to the development of new organic switchable, binary electronic materials with high data-storage capacity. Following addition of a solution of maleic anhydride to a solution of imidazo[1,2-a]pyridine(s), a cascade reaction ensues, resulting in the formation of cross-conjugated mesomeric betaines (CCMB), wherein positive and negative charges are restricted exclusively to different parts of the molecule. Physico-chemical properties of the compounds revealed the existence of intramolecular charge-transfer phenomena which could stimulate their interest as potential luminescent materials.
Molecules (Basel, Switzerland), 2016
1-alkyl aryl-5-amino-4-(cyanoformimidoyl)imidazoles 4 were reacted with malononitrile and 2-amino-1,1,3-propenetricarbonitrile under mild experimental conditions, which led to 5-amino-3-(substituted benzyl)-6,7-dicyano-3H-imidazo[4,5-b]pyridines 5 and 6,8-diamino-3-(4-substituted benzyl)-3H-imidazo[4,5-b]-1,8-naphthyridine-7,9-dicarbonitrile 6, respectively, when the reaction was carried out in the absence of a base, or to 5,7-diamino-3-(4-alkyl aryl)-3H-imidazo[4,5-b]pyridine-6-carbonitrile 8, and 6,8,9-triamino-3-(4-substitutedbenzyl)-3H-imidazo[4,5-b]-1,8-naphthyridine-7-carbonitrile 10 in the presence of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU). Both reactions evolved from an adduct formed by nucleophilic attack of the malononitrile anion or 2-amino-1,1,3-propenetricarbonitrile anion to the carbon of the cyanoformimidoyl substituent. In the case of the malononitrile anion, a 5-amino-1-alkyl aryl-4-(1-amino-2,2-dicyanovinyl)imidazole 7 was isolated when this reaction was carried ...
Multicomponent Reaction Based Synthesis of 1-Tetrazolylimidazo[1,5-a]pyridines
Organic Letters
A series of unprecedented tetrazole-linked imidazo[1,5-a]pyridines are synthesized from simple and readily available building blocks. The reaction sequence involves an azido-Ugi-deprotection reaction followed by an acetic anhydride-mediated N-acylation−cyclization process to afford the target heterocycle. Furthermore, the scope of the methodology was extended to diverse R 3-substitutions by employing commercial anhydrides, acid chlorides, and acids as an acyl component. The scope for the postmodification reactions are explored and the usefulness of the synthesis is exemplified by an improved three-step synthesis of a guanylate cyclase stimulator.
Tetrahedron Letters, 2012
An efficient method to prepare 2,3-diarylimidazo[1,2-a]pyridines is described. The procedure involves a Suzuki cross-coupling reaction followed by a direct arylation at position 3. Imidazo[1,2-a]pyridin-2-yl triflate was identified as a suitable coupling partner, permitting access to a variety of highly functionalized 2,3-diarylimidazo[1,2-a]pyridines.
RSC Advances, 2015
Original substituted pyrido[2',1':2,3]imidazo[4,5-c]isoquinolin-5-amines have been prepared following a Groebke-Blackburn-Bienaymé MCR combined with a N-deprotection and a spontaneous final cyclization step in moderate to good yields. The flexibility of the described method enables the introduction of diversities in 6 and 7 positions on the resulted scaffold using commercially available starting materials. Furthermore, a Buchwald-Hartwig cross coupling with a wide range of aryl and hetaryl halides has been successfully reported using our heterocyclic primary amine derivatives. Results and discussion The optimization of the MCR was initiated using the experimental conditions described by Maleki et al. with 2aminopyridine and 2-formylbenzonitrile as model substrates using first trimethylsilyl cyanide as functional isonitrile equivalent (Table 1, entry 1). 12 Unfortunately, after 24 hours of