Michael Addition Reactions Of Ketones Research Articles

Development of L-Proline-Based Chiral Ionic Liquids for Asymmetric Michael Reaction

Different Chiral Ionic Liquids (CIL) based on L-proline have been developed. Simple and efficient synthetic methodologies are used, allowing preparation in good yields for twelve novel CILs using L-proline as a cation or anion combined with suitable counter-ions. A detailed physical and chemical characterization of the CILs was performed to evaluate the influence of counter-ions on the final properties. The most promissory CILs were tested as efficient chiral catalysts in IL media for asymmetric Michael addition reactions of ketones and aldehydes to nitro-olefins. Similar or even better conversions and enantioselectivities (ee up to 95%) compared to the original L-proline were achieved. Additionally, a good product extraction performance using supercritical CO2 processes was obtained.

A Recyclable Organocatalyst for Asymmetric Michael Addition

In this study, a new organocatalyst derived from proline was developed and shown to be an efficient catalyst for asymmetric Michael addition reactions of ketones and aldehydes to nitroolefins with high diastereo- and enantioselectivities. (syn;anti up to 99:1, ee. up to 98 %.). Furthermore, the catalyst is easily recovered and could be reused six times without significant loss of its ability to affect the outcome of the asymmetric reactions. In addition, computational studies at the B3LYP/6-311G(d,p)//6-311 + G(2dp,f) level was conducted on a model reaction, and confirmed the following hypotheses: first, the hydrogen bonding between carboxyl group and nitro group plays an important role in catalysis, and second, the energy barrier for re-face attack in reactions of ketones to form 2S, 3R products is lower than that for the si-face attack leading to 2S, 3R products. Structural modification of a previously reported organocatalyst (lead compound in figure) was used to design an efficient and recyclable organocatalyst for asymmetric Michael addition. The introduced carboxyl group not only enhances the enantioselectivity but also brings convenience to the recovery of the catalyst.

An amphiphilic organic catalyst for the direct asymmetric Michael addition of cycloketone to nitroolefins in water

A series of amphiphilic proline-derived mercapto imidazole organic catalysts were synthesized and shown to be very effective with an acid cocatalyst for the asymmetric Michael addition reaction of ketones to nitroolefins with high diastereoselectivity (up to 99:1) and execellent enantioselectivity (up to 96%) using water as solvent.

ChemInform Abstract: Diastereoselective and Enantioselective Michael Addition Reactions of Ketones and Aldehydes to Nitro Olefins Catalyzed by C2‐Symmetric Axially‐Unfixed Biaryl‐Based Organocatalysts Derived from Enantiopure α‐Proline.

A new class of axially-unfixed biaryl-based pyrrolidines with C2-symmetry were designed and synthesized by using enantiopure α-proline as a chiral source. These bifunctional organocatalys provided Michael adducts in high chemical yields (up to 99 %) and with excellent stereoselectivities (up to 99:1 dr and 96 % ee) in the direct Michael addition reactions of a variety of ketones and aldehydes to nitro olefins. The transition states were proposed to clarify the stereochemical course of the examined reactions.

Diastereoselective and Enantioselective Michael Addition Reactions of Ketones and Aldehydes to Nitro Olefins Catalyzed by C2‐Symmetric Axially‐Unfixed Biaryl‐Based Organocatalysts Derived from Enantiopure α‐Proline

AbstractA new class of axially‐unfixed biaryl‐based pyrrolidines with C2‐symmetry were designed and synthesized by using enantiopure α‐proline as a chiral source. These bifunctional organocatalys provided Michael adducts in high chemical yields (up to 99 %) and with excellent stereoselectivities (up to 99:1 dr and 96 % ee) in the direct Michael addition reactions of a variety of ketones and aldehydes to nitro olefins. The transition states were proposed to clarify the stereochemical course of the examined reactions.

ChemInform Abstract: Proline‐Based Reduced Dipeptides as Recyclable and Highly Enantioselective Organocatalysts for Asymmetric Michael Addition.

AbstractA new family of organocatalysts is prepared and used to promote highly efficient asymmetric Michael addition reactions of ketones and aldehydes to nitroolefins.

Highly Enantioselective Michael Addition of Ketones and an Aldehyde to Nitroalkenes Catalyzed by a Binaphthyl Sulfonimide in Water

A binaphthyl sulfonimide organocatalyst was used to promote highly enantioselective and diastereoselective Michael addition reactions of ketones to nitroalkenes in water. In most cases, the products were obtained in good yields with excellent enantioselectivities and diastereoselectivities (93-97% ee, up to >99:1 dr). The catalyst could also be used in an asymmetric Michael addition of isobutyraldehyde to nitroalkenes to give the desired products in moderate yields and moderate enantioselectivities (up to 83% ee).

ChemInform Abstract: Novel Cyclic β‐Aminophosphonate Derivatives as Efficient Organocatalysts for the Asymmetric Michael Addition Reactions of Ketones to Nitrostyrenes.

Abstract Three novel catalysts based upon cyclic β-aminophosphonate derivatives 1–3 were designed to catalyze the asymmetric Michael addition reactions of ketones to β-nitrostyrenes. Among the catalysts that have been prepared in this study, cyclic β-aminophosphonic acid monoethylester 3 showed the highest catalytic ability, giving the corresponding Michael adduct in good yields, high enantioselectivities (up to 92% ee), and high diastereoselectivities (syn:anti up to 95:5).

Hydroxyphthalimide allied triazole-pyrrolidine catalyst for asymmetric Michael additions in water

A new hydroxyphthalimide-coupled triazole-pyrrolidine derivative has been synthesized and demonstrated as an efficient and stereoselective organocatalyst for the asymmetric Michael addition reaction of ketones to nitro olefins at room temperature. Good yields and high selectivities were achieved when benzoic acid was used in combination with organocatalyst 1, employing water as the reaction medium.

Chiral quaternary alkylammonium ionic liquid [Pro-dabco][BF 4]: as a recyclable and highly efficient organocatalyst for asymmetric Michael addition reactions

A novel series of chiral quaternary ammonium ionic liquids have been synthesized and shown to be very effective catalysts for the asymmetric Michael addition reactions of ketones and aldehydes to nitroolefins with excellent yields (up to 100%), diastereoselectivities ( syn/ anti = 99:1), and enantioselectivities (up to 97%). The catalytic system, an ionic liquid organocatalyst in [Bmim][BF 4], could be reused five times without a significant loss in catalytic activity or stereoselectivity.

Novel cyclic β-aminophosphonate derivatives as efficient organocatalysts for the asymmetric Michael addition reactions of ketones to nitrostyrenes

Three novel catalysts based upon cyclic β-aminophosphonate derivatives 1– 3 were designed to catalyze the asymmetric Michael addition reactions of ketones to β-nitrostyrenes. Among the catalysts that have been prepared in this study, cyclic β-aminophosphonic acid monoethylester 3 showed the highest catalytic ability, giving the corresponding Michael adduct in good yields, high enantioselectivities (up to 92% ee), and high diastereoselectivities ( syn: anti up to 95:5).

The highly enantioselective Michael addition of ketones to nitrodienes catalyzed by the efficient organocatalyst system of pyrrolidinyl-thioimidazole and chiral thioureido acid

The highly enantioselective Michael addition reaction of ketones to nitrodienes was promoted efficiently by the accessible and fine-tunable organocatalytic system of pyrrolidinyl-thioimidazole and chiral thioureido acid. The corresponding adducts were afforded in good yields with high diastereoselectivities (up to 99 : 1) and excellent enantioselectivities (up to 99% ee).

Pyrrolidine–pyridine base catalysts for the enantioselective Michael addition of ketones to chalcones

A series of pyrrolidine–pyridine base organocatalysts have been developed and 3a found to be a highly effective catalyst for the asymmetric Michael addition reactions of ketones to chalcones. The reaction generated the corresponding products 1, 5-diketones in excellent diastereoselectivities (up to >99:1 dr) and enantioselectivities (up to 100% ee).

Recyclable Merrifield resin‐supported organocatalysts containing pyrrolidine unit through A3‐coupling reaction linkage for asymmetric Michael addition

Merrifield resin-supported pyrrolidine-based chiral organocatalysts A-D through A(3)-coupling reaction linkage have been developed and found to be highly effective catalysts for the Michael addition reaction of ketones with nitrostyrenes. The reactions generated the corresponding products in good yields (up to 92%), excellent enantioselectivities (up to 98% ee), and high diastereoselectivities (up to 99:1 dr). In addition, the catalysts can be reused at least five times without a significant loss of catalytic activity and stereoselectivity.

4-Trifluoromethanesulfonamidyl prolinol tert-butyldiphenylsilyl ether as a highly efficient bifunctional organocatalyst for Michael addition of ketones and aldehydes to nitroolefins

4-Trifluoromethanesulfonamidyl prolinol tert-butyldiphenylsilyl ether bifunctional organocatalyst 3a is a highly efficient catalyst for the asymmetric Michael addition reactions of ketones and aldehydes to nitrostyrenes, leading to syn-selective adducts with excellent yields (>99%), high diastereoselectivities (up to 99:1 dr) and excellent enantioselectivities (up to 99% ee). Control experiments suggested that the trans-configuration relationship between the bulky group (–CH 2OTBDPS) and the sulfonamido group at the 4-position of the pyrrolidine ring was important to achieve high yield and stereoselectivity.

Ionic Liquid-Supported (ILS) (S)-Pyrrolidine Sulfonamide, a Recyclable Organocatalyst for the Highly Enantioselective Michael Addition to Nitroolefins

A new class of ionic liquid supported (ILS) (S)-pyrrolidine sulfonamide organocatalyst has been developed and shown to be a very effective catalyst for the asymmetric Michael addition reactions of ketones and aldehyde to nitroolefins with high enantio- and diastereoselectivities. This ILS organocatalyst is also easily recycled and could be reused at least five times without significant loss of its ability to affect the outcome of the asymmetric reactions.

Silica gel supported pyrrolidine-based chiral ionic liquid as recyclable organocatalyst for asymmetric Michael addition to nitrostyrenes

A novel silica gel supported pyrrolidine-based chiral ionic liquid 6a has been developed and found to be a highly effective catalyst for the Michael addition reaction of ketones with nitrostyrenes. The reactions generated the corresponding products in good yields (up to 94%), excellent enantioselectivities (up to >99% ee), and high diastereoselectivities (up to >99:1 dr). In addition, the catalyst 6a can be reused at least five times without a significant loss of catalytic activity and stereoselectivity.

A chiral thioureido acid as an effective additive for enantioselective organocatalytic Michael additions of nitroolefins

A novel and effective organocatalytic system consisting of pyrrolidinyl-thioimidazole and a chiral thioureido acid efficiently catalyzed the asymmetric Michael addition reactions of ketones to nitroolefins to afford the adducts with high diastereoselectivities (up to 99 : 1) and excellent enantioselectivities (up to 99% ee).

Pyrrolidine-based chiral pyridinium ionic liquids (ILs) as recyclable and highly efficient organocatalysts for the asymmetric Michael addition reactions

A novel series of pyrrolidine-based chiral pyridinium ionic liquids (ILs) have been developed by using commercially available ( S)-(2-aminomethyl)-1- N-Boc-pyrrolidine. These chiral ILs have been found to be recyclable and efficient organocatalysts for the asymmetric catalytic Michael addition reactions of ketones to nitroolefins with high yields, high enantioselectivies, and diastereoselectivies.

Highly Enantioselective Organocatalytic Michael Addition Reactions of Ketones with Chalcones.

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