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
2007; Multidisciplinary Digital Publishing Institute; Volume: 12; Issue: 11 Linguagem: Inglês
10.3390/12112546
ISSN1433-1373
AutoresMirela Filipan-Litvić, Mladen Litvić, Ivica Cepanec, Vladimir Vinković,
Tópico(s)Synthesis of Organic Compounds
ResumoHantzsch 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-methoxy-benzaldehyde 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 theliterature, was determined by 1D and 2D NMR spectra and its MS fragmentation. This isthe first example of cyclisation leading to a substituted pyran rather than 1,4-DHP undertypical Hantzsch reaction conditions. A plausible mechanism for its formation ispostulated.
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