| Autor: |
Patricia, Martínez-Bescos, Fernando, Cagide-Fagín, Luis F, Roa, Juan Carlos, Ortiz-Lara, Krzysztof, Kierus, Lidia, Ozores-Viturro, Marta, Fernández-González, Ricardo, Alonso |
| Rok vydání: |
2008 |
| Předmět: |
|
| Zdroj: |
The Journal of organic chemistry. 73(10) |
| ISSN: |
0022-3263 |
| Popis: |
The first general methodology for the gram-scale preparation of previously overlooked beta-(hetero)aryl-alpha-nitro-alpha,beta-enals (3) is reported. Condensation of (hetero)aromatic aldehydes with 2-nitroethanol gave the E-isomers of uncommon beta-(hetero)aryl-alpha-hydroxymethyl-alpha,beta-unsatured-nitroalkenes (2), as determined by NOE and X-ray studies. alpha-Nitro-alpha,beta-enals 3 were subsequently obtained by hypervalent iodine oxidation of 2 as E-Z-mixtures in solid form. They showed varied stability and solvent-dependent thermal-promoted and photopromoted E-Z interconversion. Starting with furfural, experimental conditions were developed to prepare the corresponding nitroenal 3a enriched in either the E or the Z isomer: E-3a/Z-3a approximately 90/10 and 20/80, respectively. In contrast with other structurally related compounds, nitroenals 3 have their (hetero)aryl-vinyl unit and their formyl and nitro groups all in a planar arrangement, both in solid form and in solution; accordingly, they are colored compounds with predicted high dipole moments. As deduced from solution-NMR and X-ray data, the C=C and the C=O double bonds in 3 are exclusively s- cis-oriented; this disposition corresponds in fact to the DFT-computed most stable conformer. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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