Reaction Of Enals Research Articles

One‐Step Formation both of C–N and of C–O Bonds of N‐Alkoxyamides through NHC‐Catalyzed Three‐Component Reactions of Enals, Nitrosoarenes, and Enones

AbstractNHC‐catalyzed three‐component reactions of α,β‐unsaturated aldehydes (enals), nitrosoarenes, and α,β‐unsaturated ketones (enones) were studied. The reactions proceeded through a cascade aza‐benzoin condensation/oxo‐Michael addition sequence to produce N,O‐bisfunctionalized N‐hydroxylacrylamides in moderate to good yields. This work not only provides an efficient method for the one‐step formation both of the C–N and of the C–O bonds in N‐alkoxyamides, but also advances the application of NHC organocatalysis in the field of multicomponent reactions.

N‐Heterocyclic Carbene Catalyzed Homoenolate‐Addition Reaction of Enals and Nitroalkenes: Asymmetric Synthesis of 5‐Carbon‐Synthon δ‐Nitroesters

Synthesizing synthons: The highly enantioselective title reaction is described. It employs catalytic amounts of N-heterocyclic carbene precursors and transforms a broad range of nitroalkenes, such as nitrodienes, nitroenynes, and nitrostyrenes, through reaction with a broad range of enals, into δ-nitroesters via homoenolate intermediates (see scheme).

N‐Heterocyclic Carbene Catalyzed Homoenolate‐Addition Reaction of Enals and Nitroalkenes: Asymmetric Synthesis of 5‐Carbon‐Synthon δ‐Nitroesters

Die Synthese von Synthonen: In der hoch enantioselektiven Titelreaktion werden katalytische Mengen einer N-heterocyclischen Carbenvorstufe verwendet, um eine Vielzahl an Nitroalkenen wie Nitrodiene, Nitroenine und Nitrostyrole mit einer großen Bandbreite an Enalen über Homoenolatzwischenstufen in δ-Nitroester zu überführen (siehe Schema). Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

ChemInform Abstract: Secondary Amine Catalyzed Retro‐Aldol Reactions of Enals and Enones: One‐Pot Conversion of Enals to α‐Substituted Derivatives.

AbstractOptimized conditions which include pyrrolidine as the promoter allow the retro aldol hydrolysis of cinnamaldehydes and aliphatic α,β‐unsaturated aldehydes.

ChemInform Abstract: NHC‐Catalyzed Reaction of Enals with Unactivated Enones: Substituent Effect on the Formation of 1:1 and 1:2 Adducts.

AbstractImidazole carbene catalyzed reaction of α,β‐unsaturated aldehydes with unactivated enones gives two kinds of pyranones, i.e.

Endogenous formation and significance of 1, N2-propanodeoxyguanosine adducts

The detection of 1, N 2-propanodeoxyguanosine adducts in the DNA of rodent and human tissues as endogenous lesions has raised important questions regarding the source of their formation and their roles in carcinogenesis. Both in vitro and in vivo studies have generated substantial evidence which supports the involvement of short- and long-chain enals derived from oxidized polyunsaturated fatty acids (PUFAs) in their formation. These studies show that: (1) the cyclic propano adducts are common products from reactions of enals with DNA bases; (2) they are formed specifically from linoleic acid (LA; ω-6) and docosahexaenoic acid (ω-3) under in vitro stimulated lipid peroxidation conditions; (3) the levels of propano adducts are dramatically increased in rat liver DNA upon depletion of glutathione; (4) the adduct levels are increased in the liver DNA of the CCl 4-treated rats and the mutant strain of Long Evans rats which are genetically predisposed to increased lipid peroxidation; and (5) adduct levels are significantly higher in older rats than in newborn rats. These studies collectively demonstrate that tissue lipid peroxidation is a main endogenous pathway leading to propano adduction in DNA. The possible contribution from environmental sources, however, cannot be completely excluded. The mutagenicity of enals and the mutations observed in site-specific mutagenesis studies using a model 1, N 2-propanodeoxyguanosine adduct suggest that these adducts are potential promutagenic lesions. The increased levels of the propano adducts in the tissue of carcinogen-treated animals also provide suggestive evidence for their roles in carcinogenesis. The involvement of these adducts in tumor promotion is speculated on the basis that oxidative condition in tissues is believed to be associated with this process.

Formation of etheno adducts in reactions of enals via autoxidation.

4-Hydroxy-2-nonenal (HNE) and crotonaldehyde (CA) are alpha,beta-unsaturated aldehydes (enals) produced by lipid peroxidation. Previous studies have shown that enals form tricyclic propano adducts with purine nucleosides. When epoxidized by tert-butyl hydroperoxide, enals yield the more reactive epoxy aldehydes which are capable of modifying adenine and guanine in DNA by forming etheno adducts. The epoxides are considerably more mutagenic and tumorigenic than the parent aldehydes. In this study, we found that, in addition to the propano adducts, etheno adducts are detected upon incubation of enals with deoxyadenosine (dAdo) or deoxyguanosine (dGuo) at 37 degrees C (pH 7.4). When carried out under oxygen-enriched atmosphere, the reaction of HNE with dAdo yielded 1,N6-ethenodeoxyadenosine (1,N6-EdAdo) and 7-(1',2'-dihydroxyheptyl)-1,N6-EdA in 0.03% and 0.48% yield. The reaction with dG gave 0.19% 1,N2-ethenodeoxyguanosine (1,N2-EdGuo) and 0.79% 7-(1',2'-dihydroxyheptyl)-1,N2-EdGuo. In the case of CA, the reaction with dAdo produced 7-(1'-hydroxyethyl)-1,N6-EdAdo in 0.67% yield, while the reaction with dGuo yielded 0.34% 1,N2-EdGuo and 0.97% 7-(1'-hydroxyethyl)-1,N2-EdGuo, respectively. When the above reactions were carried out under nitrogen, yields of etheno adducts were significantly reduced. These results provide evidence for a pathway by which the etheno adducts may be formed by enals via autoxidation.

ChemInform Abstract: Enantioselective Diels‐Alder Reactions of Enals: Fighting Species Multiplicity of the Catalyst with Donor Solvents.

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