Organocatalytic Asymmetric Cascade Michael-Acyl Transfer Reaction between 2-Fluoro-1,3-diketones and 2-Hydroxynitrostyrenes

An organocatalytic asymmetric cascade Michael-acyl transfer reaction of 2-hydroxynitrostyrenes and monofluorinated β-diketones has been developed employing a cooperative catalytic system. A combination of quinine-derived bifunctional squaramide catalyst and achiral hydrogen bond donor cocatalyst was found to be the most effective for this reaction and provided the fluorinated acyl transfer products in high yields with good diastereo- and excellent enantioselectivities. Synthetic transformations have been demonstrated, including the synthesis of functionalized 2,3-dihydrobenzofurans and 1-pyrroline.

Organocatalytic Asymmetric Domino [3+2]-Cycloaddition-Acyl Transfer Reaction between Azomethine Ylides and α-Nitro-α,β-Unsaturated Ketones

Herein we have developed an organocatalytic asymmetric domino [3+2]-cycloaddition-acyl transfer reaction between in situ generated azomethine ylides and α-nitro-α,β-unsaturated ketones. The desired penta-substituted pyrrolidine products were obtained in high yields and in moderate to good enantio- and diastereoselectivities. Also, an isomerization reaction in silica gel was performed for the formation of another diastereomer in high yields with retention of enantioselectivities.

Zinc-Catalyzed Asymmetric Cascade Michael/Acyl Transfer Reaction between α-Hydroxy Aryl Ketones and Enynones

We described herein a neoteric enantioselective cascade Michael/acyl transfer reaction of enynones and α-hydroxy aryl ketones catalyzed by dinuclear zinc cooperative catalysis. A series of structurally diverse chiral 1,5-dicarbonyl compounds were synthesized in good yields with excellent stereoselectivities. This strategy features broad substrate scope, high atom economy, as well as enynones as efficient electrophilic acyl transfer reagents in asymmetric cascade reactions for the first time.

Enantioselective Michael addition of malonates to β,γ-unsaturated α-ketoesters catalysed by Cu(II) complexes bearing binaphthyl-proline hybrid ligands

High yields (up to 96%) and high ee (up to 92%) were achieved for chiral copper(II) complex-catalysed enantioselective Michael addition of malonates to β,γ-unsaturated-α-ketoesters. The chiral ligands took advantage of both the binaphthyl and the proline moieties, and substituents with different electronic and steric features could be tolerated. The reactions could be carried out under mild conditions, and a gram scale reaction could be realised without the loss of yield and enantioselectivity.

Organocatalytic Asymmetric Cascade Michael-acyl Transfer Reaction between 2-Fluoro-1,3-diketones and Unsaturated Thiazolones: Access to Fluorinated 4-Acyloxy Thiazoles

Quinine derived bifunctional urea catalyzed cascade Michael-acyl transfer reaction of 5-alkenyl thiazolones and monofluorinated β-diketones has been developed. The fluorine containing 4-acyloxy thiazoles were synthesized in high yields and good diastereo-and excellent enantioselectivities. Synthetic transformations, including synthesis of 4-hydroxy thiazoles, have been demonstrated.

Organocatalytic asymmetric Michael/acyl transfer reaction between α-nitroketones and 4-arylidenepyrrolidine-2,3-diones

An organocatalytic asymmetric Michael/acyl transfer reaction between α-nitroketones and 4-arylidenepyrrolidine-2,3-diones is reported. A bifunctional thiourea catalyst was found to be effective for this reaction. With 10 mol % of the catalyst, good results were attained for a variety of 1,5-dihydro-2H-pyrrol-2-ones under mild reaction conditions.

DBU-Mediated Addition of α-Nitroketones to α-Cyano-enones and α,β-Unsaturated α-Ketoesters: Synthesis of Dihydrofurans and Conjugated Dienes

1,8-Diazabicyclo[5.4.0]undec-7-ene-mediated reactions of α-nitroketones with α-cyano-enones and α,β-unsaturated α-ketoesters have been developed. The products, namely, dihydrofurans and conjugated dienes, were isolated in moderate to good yields, and a range of substitutions were tolerated.

Employment of α-nitroketones in organic synthesis

This review summarizes the recent developments of the reactions of α-nitroketones and the consequent formation of a variety of structural frameworks is discussed.

Organocatalytic asymmetric Michael/hemiketalization/acyl transfer reaction of 1,3-propanediones with (E)-2-(2-nitrovinyl)phenols

An organocatalytic asymmetric cascade Michael/hemiketalization/acyl transfer reaction between (E)-2-(2-nitrovinyl)phenols and 1,3-propanediones is disclosed to generate products having keto, ester and nitro functionalities.

3-Hydroxy-3-((3-methyl-4-nitroisoxazol-5-yl)methyl)indolin-2-one as a versatile intermediate for retro-Henry and Friedel–Crafts alkylation reactions in aqueous medium

The first example of a retro-Henry type reaction is reported using 3-hydroxy-3-((3-methyl-4-nitroisoxazol-5-yl)methyl)indolin-2-ones which are prepared via catalyst-free Henry reaction of 3,5-dimethyl-4-nitroisoxazole and isatin.

Highly stereoselective synthesis of 2,3-dihydrofurans via a cascade Michael addition-alkylation process: a nitro group as the leaving group

The Michael addition-alkylation process between gem-benzoyl-nitrostyrenes and 1,3-dicarbonyl compounds proceeded smoothly in the presence of a bifunctional squaramide, exclusively providing 2,3-dihydrofurans as trans-diastereomers in 33-92% isolated yields and excellent enantioselectivities (29->99% ee).

Organocatalytic asymmetric Michael/hemiacetalization/acyl transfer reaction of α-nitroketones with o-hydroxycinnamaldehydes: synthesis of 2,4-disubstituted chromans

An organocatalytic asymmetric synthesis of 2,4-disubstituted chroman compounds has been developed via a Michael/hemiketalization/acyl transfer reaction between o-hydroxycinnamaldehydes and α-nitroketones.

An enantioselective cascade reaction between α,β-unsaturated aldehydes and malonic half-thioesters: a rapid access to chiral δ-lactones

We disclose a novel efficient enantioselective organocatalytic cascade reaction for the preparation of δ-lactones in good to excellent yields (69-93%) and with high to excellent enantioselectivities (88-96% ee).

An organocatalytic cascade reaction of 2-nitrocyclohexanone and α,β-unsaturated aldehydes with unusual regioselectivity

An organocatalytic cascade reaction of 2-nitrocyclohexanone and α,β-unsaturated aldehydes was developed.