Mechanisms of intramolecular transformations of carbanions generated from 2-aza-1,3,5-trienes by the action of potassium tert-butoxide, which could lead to homo-or heteroannular azacycloheptadienes, were studied by quantum-chemical methods in terms of the density functional theory. The corresponding gradient channels were localized for model 1-methylsulfanyl-1-(cyclopentylideneamino)-and 1-methylsulfanyl-1-(cyclohexylideneamino)buta-1,3-dien-2-ols. Analysis of the kinetic and thermodynamic parameters showed that carbanion generated from N-cyclopentylidenebuta-1,3-dien-1-amine undergoes rearrangement mainly into homoannular azacycloheptadiene and that analogous N-cyclohexylidene derivative gives rise to heteroannular isomer. The results of calculations were consistent with the experimental data. * For communication XV, see [1].Seven-membered nitrogen-containing heterocycles constitute structural fragments of many natural and synthetic biologically active compounds which have found wide applications in medicine and pharmacology [2]. Increased interest in these compounds stimulated search for rational ways of their synthesis, including the synthesis of new derivatives. We recently showed that 2-aza-1,3,5-trienes I available in one preparative step from α-lithiated allenes (e.g., methoxyallene or protected allenyl alcohol) and s-alkyl isothiocyanates (e.g., isopropyl isothiocyanate) (Scheme 1) [3] by the action of potassium tert-butoxide in tetrahydrofuran-dimethyl sulfoxide are readily (-30°C, 30 min) transformed into previously unknown 4,5-dihydro-3H-azepines II (Scheme 2); these results were briefly reported in [4,5].

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A Facile Linking of the Pyrrole Ring with Functionalized 3(2H)-Furanone Moieties. -(MAL'KINA, A. G.; SHEMYAKINA, O. A.; STEPANOV, A. V.; VOLOSTNYKH, O. G.; USHAKOV, I. A.; SOBENINA, L. N.; BORODINA, T. N.; SMIRNOV, V. I.; TROFIMOV*, B. A.; Synthesis 48 (2016) 02, 271-280, http://dx.doi.org/10.1055/s-0035-1560754 ; A. E. Favorsky Inst. Chem., Sib. Branch, Russ. Acad. Sci., Irkutsk 664033, Russia; Eng.) -M. Tismer 23-044

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The popular organic superbases 1,5‐diazabicyclo[4.3.0]non‐5‐ene (DBN) and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) underwent annulation with electron‐deficient propargylic alcohols [EWG = CN, C(O)Ph, CO2Me] to afford functionalized condensed hexahydropyrimidine systems, [1,3]oxazolo[3,2‐a]pyrrolo[2,1‐b]hexahydropyrimidines and [1,3]oxazolo[3′,2′:3,4] hexahydropyrimido[1,2‐a]azepines, in good to high yields. The reactions proceeded regioselectively and, in most cases, stereoselectively under mild conditions (without catalyst, 20–25 °C). The synthesized compounds, owing to their potential rich chemistry, are novel promising precursors for pyrimidine‐based pharmaceuticals.