Abstract
The title compound, C20H24N2O4, is the product of a ring-expansion reaction from a seven-membered hexa-hydro-azepine to a nine-membered azonine. The azonine ring of the mol-ecule adopts a chair-boat conformation. In the crystal, mol-ecules are linked by bifurcated N-H⋯(O,O) hydrogen bonds, generating [010] zigzag chains. The title compound shows inhibitory activity against acetyl-cholinesterase and butyrylcholinesterase, and might be considered as a candidate for the design of new types of anti-Alzheimer's drugs.
Highlights
The azonine moiety has long been known as a building block of natural alkaloids
We report on the synthesis of nine-membered azonine ring from a seven-membered hexahydroazepine precursor using a similar reaction
2-ethyl-1,2,3,4,5,6-hexahydroazepino[4,3-b]indole in a methanol solution at room temperature under the action of dimethyl acetylenedicarboxylate undergoes a series of tandem transformations involving the hexahydroazepine ring giving rise to azoninoindole (I) and 3-methoxymethyl-substituted indole (II) (Fig. 1)
Summary
The azonine moiety has long been known as a building block of natural alkaloids Azonine derivatives are known to act as ligands towards different receptors, demonstrating diverse types of biological activity (Magnus et al, 1987; Kuehne, Bornman et al, 2003; Kuehne, He et al, 2003; Afsah et al, 2009; Rostom, 2010; Tanaka et al, 2014; Soldi et al, 2015; Hartman & Kuduk, 2016). The synthesis of dimethyl 4-ethyl-1,4,5,6,7,8-hexahydroazonino[5,6b]indole-2,3-dicarboxylate, (I), in methanol. We report on the synthesis of nine-membered azonine ring from a seven-membered hexahydroazepine precursor using a similar reaction. 2-ethyl-1,2,3,4,5,6-hexahydroazepino[4,3-b]indole in a methanol solution at room temperature under the action of dimethyl acetylenedicarboxylate undergoes a series of tandem transformations involving the hexahydroazepine ring giving rise to azoninoindole (I) and 3-methoxymethyl-substituted indole (II) (Fig. 1). The interplanar angle between the carboxylate substituents is 59.74 (6)
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