A flexible approach to unknown 1-(1H-pyrrol-3-yl)pyridinium salts with selective control of the substitution patterns, by the reaction of pyridinium ylides with 2H-azirines, is disclosed. 3-(Pyridinium-1-yl)pyrrolides, a new type of stable ylide, were prepared from these salts in high yields by treatment with base. Atmospheric-pressure hydrogenation of the ylides with Adams' catalyst lead to 1-(pyrrol-3-yl)piperidines in good yields.

An effective approach to azepino-fused heterocycles is described. trans-1-Aryl-7,11b-dihydro-1H-azirino[1,2-a]dibenzo[c,f]azepines were synthesised via a domino sequence: isomerization of gem-dichloroaziridine-intramolecular Friedel-Crafts acylation of the tethered benzene ring catalysed by SnCl(4) and subsequent hydride induced intramolecular cyclization. Cycloaddition of dibenzazepinium ylides, generated by heating these aziridines, to activated C[double bond]C, C[triple bond]C dipolarophiles and fullerene C(60), leads to derivatives of dibenzo[c,f]pyrrolo[1,2-a]azepine. The reaction proceeds with complete stereoselectivity via cycloaddition of only W-ylide, which due to the high barrier does not undergo E,Z-isomerization under the reaction conditions. It was found that 2,3,9,13b-tetrahydro-1H-dibenzo[c,f]pyrrolo[1,2-a]azepine systems can exist in conformations of two types depending on the substituents at the pyrrolidine carbons in β-position with respect to nitrogen. Details of cycloaddition reactions and the conformational behavior of cycloadducts were studied by DFT calculations at the B3LYP/6-31G(d) level.

An Efficient Approach to Azirino and Pyrrolo-Fused Dibenzazepines. Conformations of Substituted Dibenzo[c,f]pyrrolo[1,2-a]azepines. -The dibenzopyrroloazepines can exist in two different conformations depending on the nature of substituents. -(KHLEBNIKOV*, A. F.; NOVIKOV, M. S.; GOLOVKINA, M. V.; PETROVSKII, P. P.; KONEV, A. S.; YUFIT, D. S.; STOECKLI-EVANS, H.; Org. Biomol. Chem. 9 (2011) 10, 3886-3895, http://dx.doi.org/10.1039/c1ob05081h ; Dep. Chem., St. Petersburg State Univ., St. Petersburg 198904, Russia; Eng.) -Jannicke 40-170

Unknown pyridinium salts are generated with complete regioselectivity.