A convenient method for the synthesis of 2-azido-3-arylpropanoic acids via the Meerwein halogenoarylation reaction of acrylic acid esters with diazonium salts, subsequent nucleophilic substitution of the halogen by an azide, and saponification is developed. The newly formed 2-azido-3-arylpropanoic acids react under the conditions of non-catalytic four-component Ugi reactions, leading to the formation of α-azidoamides in good yields. The use of propargylamine as the amine component allows the formation of Ugi adducts with azide and acetylene motifs ready for intramolecular 1,3-dipolar Huisgen cycloaddition to give the [1,2,3]triazolo[1,5-a]pyrazine annulated system. The Ugi reaction is found to give 2-azido-3-aryl-N-(2-oxo-1,2-disubstituted ethyl)-N-(prop-2-yn-1-yl)propanamides at room temperature without azide–alkyne cycloaddition. These dipeptides are converted into 4,5-dihydro[1,2,3]triazolo[1,5-a]pyrazin-6(7H)-ones in near quantitative yields by heating in toluene. However, when the Ugi reaction is carried out by heating, it results in a one-pot Ugi–Huisgen tandem reaction leading to 4,5-dihydro[1,2,3]triazolo[1,5-a]pyrazin-6(7H)-ones in excellent yields. Moreover, the possibility of the incorporation of a bromovinyl fragment (the synthetic equivalent of an acetylene fragment) via the aldehyde component of the Ugi reaction is demonstrated in an alternative preparation of the [1,2,3]triazolo[1,5-a]pyrazine system.
Thiazole derivatives R 0260Synthesis and Antimicrobial Activity of 5-(R 1 -Benzyl)-2-(R-benzylidenehydrazono)-3-(2-furylmethyl)thiazolidin-4-ones. -Among the title thiazolidinones prepared, only derivatives (IIIa) and (IIIb) containing a tolylmethyl residue at the thiazolidinone ring possess antimicrobial activity. -(TSYALKOVSKII, V. M.; KUTSYK, R. V.; MATIYCHUK, V. S.; OBUSHAK, M. D.; KLYUFINSKA, T. I.; Khim.-Farm. Zh. 39 (2005) 5, 20-22; L'viv Natl. Univ., L'viv 79602, Ukraine; Russ., Abstr. Eng.) -Mischke 41-132
Unsaturated Compounds. Part 9. Dialkyl 2,6-Diamino-4-arylfuro[2',3':4,5]benzo[b]furan-3,7-dicarboxylates from 2-Aryl-1,4-benzoquinones and Cyanoacetic Esters. -Interaction of benzoquinone derivatives (I), prepared by arylation of 1,4-benzoquinone with arenediazonium chlorides via Meerwein reaction with cyanoacetic esters (II), results unexpectedly in the selective formation of benzodifuran derivatives (III) (12 examples) regardless of the reagent ratio. -(OBUSHAK*, M. D.; MARTYAK, R. L.; MATIYCHUK, V. S.; Pol.
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