Hantzsch Synthesis of 2,6-Dimethyl-3,5-dimethoxycarbonyl-4-(o-methoxyphenyl)-1,4-dihydropyridine; a Novel Cyclisation Leading to an Unusual Formation of 1-Amino-2-methoxycarbonyl-3,5-bis(o-methoxyphenyl)-4-oxa-cyclohexan-1-ene

Filipan-Litvić, Mirela; Litvić, Mladen; Cepanec, Ivica; Vinković, Vladimir (2007) Hantzsch Synthesis of 2,6-Dimethyl-3,5-dimethoxycarbonyl-4-(o-methoxyphenyl)-1,4-dihydropyridine; a Novel Cyclisation Leading to an Unusual Formation of 1-Amino-2-methoxycarbonyl-3,5-bis(o-methoxyphenyl)-4-oxa-cyclohexan-1-ene. Molecules, 12 (11). pp. 2546-2558. ISSN 1420-3049

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Official URL: https://doi.org/10.3390/12112546

Abstract

Hantzsch condensation of two equivalents of methyl-3-aminocrotonate with (m- and p)-methoxybenzaldehyde afforded the expected products 2, 6-dimethyl-3, 5-dimethoxycarbonyl-4-(m-methoxyphenyl)-1, 4-dihydropyridine and 2, 6-dimethyl-3, 5-dimethoxycarbonyl-4-(p-methoxyphenyl)-1, 4-dihydropyridine, whereas o-methoxybenzaldehyde produced mainly 1-amino-2-methoxycarbonyl-3, 5-bis(o-methoxy-phenyl)-4-oxa-cyclohexan-1-ene. The structure of the product, not previously reported in the literature, was determined by 1D and 2D NMR spectra and its MS fragmentation. This is the first example of cyclisation leading to a substituted pyran rather than 1, 4-DHP under typical Hantzsch reaction conditions. A plausible mechanism for its formation is postulated.

Item Type:

Article

Uncontrolled Keywords:

Hantzsch condensation; intramolecular Michael addition; deprotonation; substituted pyrane

Subjects:

NATURAL SCIENCES > Chemistry

Divisions:

Division of Organic Chemistry and Biochemistry

Projects: