Synthesis, Structure, and E−Z Isomerization of β-(Hetero)aryl-α-nitro-α,β-enals
摘要:
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 approximate to 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.
Synthesis, Structure, and E−Z Isomerization of β-(Hetero)aryl-α-nitro-α,β-enals
摘要:
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 approximate to 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.
[EN] PROCESSES FOR THE PREPARATION OF PANCRATISTATIN AND PANCRATISTATIN ANALOGUES<br/>[FR] PROCÉDÉS DE PRÉPARATION DE PANCRATISTATINE ET D'ANALOGUES DE PANCRATISTATINE
申请人:UNIV SANTIAGO COMPOSTELA
公开号:WO2009026961A1
公开(公告)日:2009-03-05
Processes for the preparation of pancratistatin and pancratistatin analogues. The key step is the reaction of a 1,3-dioxan-5-one and a nitroolefine in the presence of an amine. The process may take place in an enantioselective way when a chiral amine is used. Reduction processes then give new and advanced intermediates that are useful for the preparation of pancratistatin or selected pancratistatin analogues. The reported process also provides a method for the efficient synthesis of nitroenals, starting materials of the synthesis. Analogues of pancratistatin are also provided.
Synthesis and evaluation of α-hydroxymethylated conjugated nitroalkenes for their anticancer activity: Inhibition of cell proliferation by targeting microtubules
作者:Renu Mohan、Namrata Rastogi、Irishi N.N. Namboothiri、Shaikh M. Mobin、Dulal Panda
DOI:10.1016/j.bmc.2006.07.035
日期:2006.12
(MBH) type reaction of a variety of aromatic and heteroaromatic conjugatednitroalkenes with formaldehyde in the presence of stoichiometric amounts of imidazole and catalytic amounts (10 mol %) of anthranilic acid at room temperature provided the corresponding hydroxymethylated derivatives in moderate to good yield. The parent nitroalkenes and their MBH adducts were subsequently screened for their anticancer
The Morita–Baylis–Hillmanreaction (MBHR) of conjugated nitroalkenes has been successfully carried out for the first time. A variety of aromatic and heteroaromatic nitroalkenes react with formaldehyde at room temperature in the presence of stoichiometric amounts of imidazole and catalytic amounts of anthranilic acid in THF providing moderate to good yields of the multifunctional adducts in most of
Synthesis, Structure, and <i>E</i>−<i>Z</i> Isomerization of β-(Hetero)aryl-α-nitro-α,β-enals
作者:Patricia Martínez-Bescos、Fernando Cagide-Fagín、Luis F. Roa、Juan Carlos Ortiz-Lara、Krzysztof Kierus、Lidia Ozores-Viturro、Marta Fernández-González、Ricardo Alonso
DOI:10.1021/jo702731b
日期:2008.5.1
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 approximate to 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.