Ludmila V. Andriyankova

A facile annelation of pyridines with nitriles of α,β-acetylenic γ-hydroxyacids

Pyridines are readily annelated with nitriles of α,β-acetylenic γ-hydroxyacids under mild conditions (ambient temperature, no catalyst, no solvent) to give new condensed dihydropyridine systems, 4-cyanomethylidene-1,3-oxazolidine[3,2-a]-1,2-dihydropyridines in 75–83% yields.

Stereoselective tandem ring opening of imidazoles with electron-deficient acetylenes and water: synthesis of functionalized (Z,Z)-1,4-diaza-2,5-dienes.

1-Substituted imidazoles undergo exceptionally facile stereoselective ring opening under the influence of electron-deficient acetylenes and water (equimolar ratio of the reactants) in MeCN at 45-60 °C without any catalysts to afford functionalized (Z,Z)-1,4-diaza-2,5-dienes, (Z,Z)-propenylaminoethenylformamides, in up to 80% yields. The reaction is rationalized to proceed in a tandem manner via zwitterionic vinyl carbanions formed by nucleophilic addition of imidazole to the triple bond. The carbanionic center is then quenched with water followed by the rearrangement of the intermediate 2-hydroxy-3-alkenylimidazolines.

AN UNEXPECTED CYCLIZATION DURING NUCLEOPHILIC ADDITION OF 5-MERCAPTOQUINOLINE TO PHENYLACETYLENE

Reaction of 5-mercaptoquinoline with phenylacetylene (KOH, dioxane, 160–170°C, 1 h, autoclave) gives (along with the normal adduct Z-5-styrylthioquinoline) 3-phenylthiopyrano[4,3,2-d,e]quinoline, the product of a unique intramolecular nucleophilic substitution of hydrogen by carbanion at position 4 of the quinoline ring.