1750-74-9Relevant articles and documents
Enamines as Surrogates of Alkyl Carbanions for the Direct Conversion of Secondary Amides to α-Branched Ketones
Liu, Yong-Peng,Wang, Shu-Ren,Chen, Ting-Ting,Yu, Cun-Cun,Wang, Ai-E,Huang, Pei-Qiang
supporting information, p. 971 - 975 (2019/01/25)
A direct transformation of secondary amides into α-branched ketones with enamines as soft alkylation reagents was developed. In this reaction, enamines serve as surrogates of alkyl carbanions, rather than the conventional enolates equivalents in the Stork's reactions, which allowed for the easy introduction of alkyl groups with electrophilic functional groups. In the presence of 4 ? molecular sieves, the method can be extended to the one-pot coupling of secondary amides with aldehydes to yield ketones. (Figure presented.).
Exploiting Carbonyl Groups to Control Intermolecular Rhodium-Catalyzed Alkene and Alkyne Hydroacylation
Coxon, Thomas J.,Fernández, Maitane,Barwick-Silk, James,McKay, Alasdair I.,Britton, Louisa E.,Weller, Andrew S.,Willis, Michael C.
, p. 10142 - 10149 (2017/08/02)
Readily available β-carbonyl-substituted aldehydes are shown to be exceptional substrates for Rh-catalyzed intermolecular alkene and alkyne hydroacylation reactions. By using cationic rhodium catalysts incorporating bisphosphine ligands, efficient and selective reactions are achieved for β-amido, β-ester, and β-keto aldehyde substrates, providing a range of synthetically useful 1,3-dicarbonyl products in excellent yields. A correspondingly broad selection of alkenes and alkynes can be employed. For alkyne substrates, the use of a catalyst incorporating the Ampaphos ligand triggers a regioselectivity switch, allowing both linear and branched isomers to be prepared with high selectivity in an efficient manner. Structural data, confirming aldehyde chelation, and a proposed mechanism are provided.
Photochemical reactions of 1,2-diketones with silyl enol ethers
Park, Hea Jung,Yoon, Ung Chan,Kim, Sung Hong,Sohn, Youngku,Cho, Dae Won,Mariano, Patrick S.
, p. 419 - 431 (2015/01/30)
Results arising from the current study demonstrate that UV irradiationinduced photoaddition reactions of the 1,2-diketones, acenaphthenequinone, 9, 10-phenanthrenequinone, and benzil, with silyl enol ethers derived from propionaldehyde and isobutyraldehyde take place to form a variety of adducts. Product formation in these cases takes place mainly via two mechanistic pathways, one initiated by single electron transfer (SET) and the other by [2 + 2]-cycloaddition. In addition, observations show that the competition between these pathways depends on the nature of the substrates. An exploration of the photoreactions of acenaphthenequinone revealed that photoinduced SET is the predominant process occurring when the dimethyl-substituted silyl enol ether serves as a reactant, while cycloaddition and other excited state reactions become competitive with SET when the mono-methyl substituted silyl enol ether is used as a substrate. In the case of 9,10-phenanthrenequinone, photoreactions take place by [4 + 2]-cycloaddition routes regardless of the nature of the silyl enol ether employed. Finally, irradiation of benzil in the presence of both silyl enol ethers leads to exclusive or predominant formation of products arising by [2 + 2]-cycloaddition and photoinduced benzoyl radical forming α-cleavage.
α-formylation of α-substituted ketones
Hassan, Jamal,Richards, Christopher J.
scheme or table, p. 239 - 242 (2012/03/22)
The reaction of (chloromethylene)dimethylammonium chloride (generated in situ from oxalyl chloride and DMF) with α-substituted ketones in CH 2Cl2, followed by workup with aqueous NaHCO3, gave β-keto aldehydes containing an
SmI2-mediated 3-exo-trig cyclisation of δ-oxo-α, β-unsaturated esters to cyclopropanols and derivatives
Bezzenine-Lafollée, Sophie,Guibé, Francois,Villar, Hélène,Zriba, Riadh
, p. 6931 - 6944 (2007/10/03)
In the presence of samarium diiodide and a proton source, δ-oxo-γ,γ-disubstituted-α,β-unsaturated esters of general formula R-CO-C(R′,R′)-CHCH-CO2Bn readily cyclise to trans-cyclopropanol products and/or lactones derived from the cis isomers. F
EPR Spectral Determination of Electronic Substituent Effects on the D Values of Hydrocarbon Polyradicals (Quintet and Septet Spin States) Composed of Localized 1,3-Cyclopentanediyl Spin-Carrying Units Linked by 1,3-Di- And 1,3,5-Trimethylenebenzene Ferromagnetic Couplers
Adam, Waldemar,Maas, Wiebke
, p. 7650 - 7655 (2007/10/03)
The parent and p-nitrophenyl-substituted diradicals D-3a,b (triplets), tetraradicals T-3a,b (quintets), and hexaradicals H-3a,b (septets) were photochemically generated in matrix-isolated form (toluene, 77 K) by successive denitrogenation of the trisazoalkanes 3a,b and EPR spectrally characterized. In these high-spin polyradicals the spin-spin interaction within the localized spin-carrying 1,3-cyclopentanediyl diradical unit is much stronger than within the cross-conjugated ferromagnetic coupling unit. Accordingly, a change of the electronic properties in the cyclopentanediyl unit affects decisively the D value of the whole polyradical. Therefore, the spin-accepting p-nitro group reduces the D value of the tetra- and hexaradical in the same amount as that of the diradical. Thus, irrespective of the spin multiplicity, the substituent stabilizes electronically the triplet (D-3a,b), quintet (T-3a,b), and septet (H-3a,b) species with equal efficacy.
