Spirocyclohexadienones: X. Three-component condesation of 1,2,3- and 1,2,4-trimethoxybenzenes with cyclohexanecarbaldehyde and nitriles. Synthesis of 1,2- and 1,4-dimethoxy-14-azadispiro[5.1.5.2]pentadeca-1,4-dien-3-ones

Plekhanova, I. V.; Stryapunina, O. G.; Глушков, В. А.; Karmanov, V. I.; Майорова, О. А.; Shklyaev, Yu. V.

doi:10.1134/s1070428009030038

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“…As in the previous case, doublets from diastereotopic protons on C 4 in the 1 H NMR spectra of unsymmetrically substituted initial compounds were converted into singlets at δ 2.79-2.84 ppm (IIa-IIe), and two singlets from geminal methyl groups on C 3 were transformed into one singlet at δ 1.50-1.52 ppm. Hydrolysis of dispiro compounds, e.g., of 1,2-dimethoxy-15-phenyl-14-azadispiro[5.1.5.2]pentadeca-1,4,14-trien-3-one [3]) involved opening of the central pyrrole ring (Scheme 3). Fusion of a benzene ring to the cyclohexadiene fragment increases stability of the spirocyclic system.…”

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confidence: 99%

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Spirocyclohexadienones: XII. Dienone-phenol rearrangement of 1-substituted 2-azaspiro[4.5]undeca-1,6,9-trienes and their analogs

et al. 2011

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Hydrolytic cleavage of 1-substituted 2-azaspiro[4.5]undeca-1,6,9-trienes in acid medium is accompanied by dienone-phenole rearrangement with formation of substituted N- [2-(p-hydroxyphenyl)ethyl] carboxylic acid amides. 1,2-Dimethoxy-3-oxo-15-phenyl-14-azadispiro[5.1.5.2]pentadeca-1,4,14-triene and 2′-R-7a′-methyl-3a′,4′,5′,6′,7′,7a′-hexahydrospiro[cyclohexa[2,5]diene-1,3′-indol]-4-ones undergo analogous cleavage. * For communication XI, see [1].It is known that three-component condensation of anisole derivatives with isobutyraldehyde and nitriles leads to the formation of substituted 2-azaspiro[4.5]-undeca-1,6,9-trienes [1, 2]. Analogous reaction with cyclohexanecarbaldehyde yields dispiro compounds [3]. 1-and 2-Methoxynaphthalenes behave in a similar way [4], whereas 2-methyl-1-(p-methoxyphenyl)-cyclohexan-1-ol gives rise to 2′-substituted 7a′-methyl3a′,4′,5′,6′,7′,7a′-hexahydrospiro[cyclohexa[2,5]diene-1,3′-indol]-4-ones [5]. The above listed spiro compounds characteristically undergo hydrolytic cleavage in acid medium, which is accompanied by dienonephenol rearrangement with formation of substituted N-[2-(p-hydroxyphenyl)ethyl] carboxylic acid amides [6]. Such rearrangement of spiro cyclohexadienone derivatives having no substituents in the cyclohexane ring was studied by us previously, and its mechanism was analyzed by quantum-chemical calculations [6,7].The goal of the present work was to study dienonephenol rearrangement of substituted 2-azaspiro[4.5]-undeca-1,6,9-trienes and structurally related 2′-R-7a′-methyl-3a′,4′,5′,6′,7′,7a′-hexahydrospiro-[cyclohexa[2,5]diene-1,3′-indol]-4-ones. The reactions were carried out by heating the initial spiro compound for a short time (0.5 h) in aqueous ethanol containing concentrated sulfuric acid. The presence of methoxy groups in the cyclohexadiene ring of 2-azaspiro[4.5]-undeca-6,9-dienes and 2-azaspiro[4.5]undeca-1,6,9-trienes did not affect the reaction course, and the process occurred in a way similar to hydrolytic cleavage of spiro compounds derived from anisole which had no substituents in the cyclohexadiene ring [6] (Scheme 1). Scheme 1.

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confidence: 99%

“…Analogous reaction with cyclohexanecarbaldehyde yields dispiro compounds [3]. 1-and 2-Methoxynaphthalenes behave in a similar way [4], whereas 2-methyl-1-(p-methoxyphenyl)-cyclohexan-1-ol gives rise to 2′-substituted 7a′-methyl3a′,4′,5′,6′,7′,7a′-hexahydrospiro[cyclohexa[2,5]diene-1,3′-indol]-4-ones [5].…”

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confidence: 99%