Highly efficient procedure for the conjugate addition of amines to electron deficient alkenes

The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. The results showed that the catalyst was very efficient for the reactions with the excellent yields in several minutes. Operational simplicity, without need of any solvent, low cost of the catalyst used, high yields, reusability, excellent chemoselectivity, applicability to large-scale reactions are the key features of this methodology. The article is published in the original.     

Highly efficient heterogeneous procedure for the conjugate addition of amines to electron deficient alkenes

The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. K₂CO₃ supported on different carriers have been synthesized for the conjugate addition of amines and alkenes. After optimizing the reaction conditions, K₂CO₃/MgO was chosen as the most efficient catalyst for the reactions. The results showed that the catalyst was very efficient for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes. Operational simplicity, without need of any solvent, low cost of the catalyst used, high yields, reusability, excellent chemoselectivity, and applicability to large-scale reactions are the key features of this methodology. Supported by the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science and Technology of China (Grant No. 2006BAE03B06), Shanghai Leading Academic Discipline Project (Grant No. B409), and Shanghai International Cooperation of Science and Technology Project (Grant No. 06SR07101)     

Bromodimethylsulfonium bromide mediated Michael addition of amines to electron deficient alkenes

Bromodimethylsulfonium bromide has been found to be an efficient catalyst for the Michael addition of a wide variety of amines to electron deficient alkenes at room temperature. The protocol is very simple and chemoselective. Aliphatic and benzylic amines undergo conjugate addition within a very short period under solvent-free conditions and provide excellent yields of products.     

Catalysis by an ionic liquid: efficient conjugate addition of thiols to electron deficient alkenes catalyzed by molten tetrabutylammonium bromide under solvent-free conditions

An inexpensive and readily available ionic liquid, tetrabutylammonium bromide in the molten state, efficiently catalyzes the conjugate addition of thiols to α,β-unsaturated nitriles, carboxylic ester, ketones and aldehydes as well as nitro olefins.     

Poly(N-vinylimidazole) as efficient recyclable catalyst for the Michael addition of CH-acids to electron deficient alkenes in water

Russian Chemical Bulletin - Efficiency of poly(N-vinylimidazole) as the basic recyclable catalyst for the Michael addition of CH-acids to acrylonitrile, methyl acrylate, methyl vinyl ketone and...     

Efficient electrocatalytic addition reactions of allyl phenyl sulfone to electron deficient alkenes

The use of tetraalkylammonium salts as electrolytes has been found to allow the formation of electrogenerated bases of especially high reactivity. Such conditions allow allyl phenyl sulfone to undergo addition to a variety of electron deficient vinyl and propenyl compounds (sulfone, ketone, nitrile, and ester). The additions are catalyzed by electrogenerated bases derived from the reactant itself, rather than via an added pro-base. The nature of the substrate molecule is seen to affect which type of product is formed, leading to an interplay between addition to 1 mol of substrate or to 2 mol of substrate. Yields of 1:1 adducts range from 6 to 81%, while yields of 1:2 adducts range from 57 to 96%.     

Graphene oxide: an efficient and reusable carbocatalyst for aza-Michael addition of amines to activated alkenes

Graphene oxide was found to be a highly efficient, reusable and cost-effective organocatalyst for the aza-Michael addition of amines to activated alkenes to furnish corresponding β-amino compounds in excellent yields.     

Enantioselective conjugate addition of aliphatic thiols to divergently activated electron poor alkenes and dienes

Divergently activated double bonds in electron poor 4-oxo-butenoates and (2E,4E)-6-oxo-2,4-dienoates underwent stereoselective and regioselective addition of mercaptans catalyzed by simple Cinchona alkaloids. Application of quinine and quinidine afforded both enantiomers of the 1,4-adducts with respect to the ketone carbonyl group in ees of up to 80%. Single recrystallization of some adducts resulted in further enrichment of up to 99%ee.     

A simple and green procedure for the conjugate addition of thiols to conjugated alkenes employing polyethylene glycol (PEG) as an efficient recyclable medium

Polyethylene glycol (PEG) is found to be an inexpensive, nontoxic, environmentally friendly reaction medium for the conjugate addition of thiols to conjugated alkenes to afford the corresponding adducts in excellent yields under mild and neutral conditions. Products of undesirable side reactions resulting from polymerization are not observed. The use of PEG avoids the use of either acid or base catalysts for this conversion and moreover PEG can be recovered and reused.     

Photoinduced cycloadditions of electron deficient nitrones to alkenes

Oxaziridines are proposed as intermediates in the photoinduced cycloadditions of electron deficient nitrones to dipolarophiles.     

Diastereoselection in the nucleophilic conjugate addition of amines to 2-hydroxyalkylpropenoates

Nucleophilic conjugate addition of benzylamine to 2-hydroxyalkylpropenoates 1a-c proceeds in high yield with modest diastereoselection. However, addition of benzylamine to the silyl ether of 1c produces only the anti-isomer 2d in high yield.     

Rhodium-catalyzed 1,4-addition of alkenylzirconocene chlorides to electron deficient alkenes

The 1,4-conjugated addition of alkenylzirconocene chloride complexes to α,β-enones, α,β-enoic acid esters, and α,β-enoic acid amides can be efficiently achieved by the use of [RhCl(cod)]₂ catalyst. A high diastereoselectivity (95% yield, 90% de) was obtained through the reaction of α,β-enoic acid amide derived from Oppolzer's sultam and 2-butenoyl chloride, while the use of Evans' chiral oxazolidinone as a chiral auxiliary in place of Oppolzer's sultam gave a poor diastereoselectivity (98% yield, 26% de).     

Green protocol for conjugate addition of amines to p-quinones accelerated by water

Amines undergo smooth conjugate addition to p-quinones in H₂O at ambient temperature in the absence of a catalyst to produce 2-aminoquinones in excellent yields. Significant rate acceleration of this reaction is observed in H₂O compared to organic solvents. H₂O played a dual role in simultaneously activating the p-quinone and amine. This new methodology constitutes an easy, highly efficient, and green synthesis of substituted p-quinones. Correspondence: J. S. Yadav, Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad 500007, India.     

β-Cyclodextrin promoted aza-Michael addition of amines to conjugated alkenes in water

Highly efficient and environmentally benign aza-Michael additions of amines to α,β-unsaturated compounds catalyzed by β-cyclodextrin in water to produce the corresponding β-amino compounds in excellent yields under mild conditions are described. β-Cyclodextrin can be recovered and reused in subsequent reactions without loss of activity.     

Decarbonylative radical conjugate addition of aliphatic aldehydes for alkylation of electron-deficient alkenes

A convenient metal-free decarbonylative radical conjugate addition of aliphatic aldehydes to electron-deficient alkenes is developed. With DTBP as an oxidant and radical-initiator, this reaction smoothly converts α-unsubstituted, α-mono-substituted and α-di-substituted aliphatic aldehydes into the corresponding primary, secondary and tertiary alkyl radicals, and subsequently allows for the cascade construction of C(sp³)C(sp³) bond via radical conjugate addition.     

Photochemical electron transfer mediated addition of naphthylamine derivatives to electron-deficient alkenes

Using photochemical electron transfer, N,N-dimethylnaphthylamine derivatives are added to α,β-unsaturated carboxylates. The addition takes place exclusively in the α-position of electron-deficient alkenes and mainly in the 4-position of N,N-dimethylnaphthalen-1-amine. A minor regioisomer results from the addition in the 5-position of this naphthylamine. A physicochemical study reveals that the fluorescence quenching of N,N-dimethylnaphthalen-1-amine is diffusion-controlled and that the back electron transfer is highly efficient. Therefore no transformation is observed at lower concentrations. To overcome this limitation and to induce an efficient transformation, minor amounts of water or another proton donor as well as an excess of the naphthylamine derivative are necessary. A mechanism involving a contact radical ion pair is discussed. Isotopic labeling experiments reveal that no hydrogen is directly transferred between the substrates. The hydrogen transfer to the furanone moiety observed in the overall reaction therefore results from an exchange with the reaction medium. An electrophilic oxoallyl radical generated from the furanone reacts with the naphthylamine used in excess. Concerning some mechanistic details, the reaction is compared with radical and electrophilic aromatic substitutions. The transformation was carried out with a variety of electron-deficient alkenes. Sterically hindered furanone derivatives are less reactive under standard conditions. In a first experiment, such a compound was transformed using heterogeneous electron transfer photocatalysis with TiO(2).     

Novel imidazolidine-tetrazole organocatalyst for asymmetric conjugate addition of nitroalkanes

The Michael addition of nitroalkanes to alpha,beta-unsaturated enones catalyzed by a novel chiral imidazolidine-2-yltetrazole organocatalyst has been investigated. The new more soluble organocatalyst decreases reaction times and improves enantioselectivities compared to other catalysts. The Michael addition adducts were obtained with up to 92% ee. [reaction: see text]     

Chemo/regioselective Aza-Michael additions of amines to conjugate alkenes catalyzed by polystyrene-supported AlCl3

A simple and efficient procedure is presented for Aza-Michael additions of various amines with conjugate alkenes bearing electron withdrawing group catalyzed by polystyrene-supported aluminum chloride (Ps-AlCl₃) without the use of any solvents. The catalyst shows high catalytic activity for both aromatic amines and aliphatic amines. Chemoselective additions of the two types of amines with conjugate alkenes are achieved. Regioselective additions of two different amino groups in one molecule proceed smoothly. Ps-AlCl₃ has better recyclability and can be reused several times without apparent loss of activity.