An efficient approach to azirino and pyrrolo-fused dibenzazepines. Conformations of substituted dibenzo[c,f]pyrrolo[1,2-a]azepines

Abstract

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.

Synthesis of Fused Dihydroazepine Derivatives of Fullerenes by a Rh‐Catalyzed Cascade Process

“…These promiscuous intermediates readily react with a dienophile present in the reaction mixture, providing fused dihydroazepine polycyclic systems. [40] Given that fullerene adducts containing 7-membered rings are scarce and challenging to prepare, [41][42][43][44][45][46][47] and azepane based compounds showed a variety of pharmacological properties, [48] we envisaged a synthetic protocol to prepare structurally appealing fused dihydroazepine derivatives of C 60 and C 70 by in situ generation of the 1,3-diene (Scheme 1).…”

Conformers of diheteroaryl ketones and thioketones: a quantum chemical study of their properties and fundamental intramolecular energetic effects

“…Interestingly, different conformers may possess quite distinct properties [3][4][5], and therefore, investigating the conformational behavior of chemical compounds is important from a practical point of view. From a more fundamental standpoint, the information about the preferred conformer of a given compound is helpful in understanding the intramolecular forces governing the conformational behavior of this compound [6][7][8].…”

Fused aziridines as sources of azomethine ylides

“…The stereoselective reaction makes it possible to obtain fulleropyrrolidines 30 with yields of up to 56% both by convection heating and by microwave irradiation [16,17]. The heating of aziridines 26a,b with dimethyl acetylenedicarboxylate (DMAD) in toluene leads to the stereoselective formation of high yields of pyrrolines 31a,b, which are dehydrogenated to the corresponding pyrroles 32a,b under mild conditions [16,17]. The azomethine ylide generated from the aziridine 33 reacts stereoselectively with methyl propiolate, tetrolate, and phenylpropiolate with the formation of a mixture of regioisomeric adducts 34a-c and 35a-c with yields of 73-92% [17].…”

“…A recently proposed simple method for the synthesis of azirinodibenzazepines and oxazepines 26a,b made it possible to use these compounds as sources of azomethine ylides 27a,b and to obtain a wide range of potential biologically active pyrrolodibenzazepines and oxazepines 28a,b and 29a,b [15,16]. Dipolarophiles RHC=CHR…”