Asymmetric addition of diethylzinc to aldehydes catalyzed by a camphor-derived β-amino alcohol

The asymmetric addition of diethylzinc to aromatic and aliphatic aldehydes, including linear aliphatic ones, catalyzed by 2 mol % of β-amino alcohol (1S, 2R)-7,7-dimethyl-1-morpholin-4-yl-bicyclo[2.2.1]heptan-2-ol 10 gave the corresponding secondary alcohols in high yields and with up to 94% ee at ambient temperature after 15 min.     

Asymmetric Michael addition of aldehydes to nitroolefins catalyzed by a pyrrolidine–pyrazole

An effective protocol for the stereoselective Michael addition of aldehydes to nitroolefins using pyrrolidine–pyrazole as an organocatalyst is described. The catalytic cycle was found to be productive in terms of yield and selectivity, when performed under solvent-free reaction conditions and employing 15 mol % of catalyst and 10 mol % of benzoic acid at room temperature.     

High enantioselective Michael addition of malonates to β,γ-unsaturated α-ketoesters catalyzed by bifunctional thioureas

A highly enantioselective Michael addition of malonates to β,γ-unsaturated α-ketoesters was achieved using cinchona alkaloid-derived thioureas as the bifunctional catalyst. The corresponding Michael addition products were obtained in excellent yields (90–99%) and ee values (up to >99% ee) using a quinidine-derived thiourea as the catalyst under neat conditions. The opposite enantiomer may be obtained using a quinine- or cinchonidine-derived thiourea as the catalyst.     

Asymmetric Michael addition of substituted rhodanines to α,β-unsaturated ketones catalyzed by bulky primary amines

A bulky group was introduced by design into a diamine catalyst, and a series of robust and tunable bulky chiral primary amine catalysts were developed and successfully applied in the direct conjugate addition of substituted rhodanines to α,β-unsaturated ketones. High yields (up to 99%) and excellent diastereoselectivities (up to 99:1 dr) and enantioselectivities (up to 98% ee) were observed.     

Nitrosonium （NO^＋） catalyzed Michael addition of indoles to unsaturated enones

An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in the presence of a catalytic amount of nitrosonium tetrafluoroborate in ethyl ether. 2007 Long Min Wu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.     

Asymmetric Michael addition of 1-acetylindolin-3-ones to β-nitrostyrenes catalyzed by bifunctional thioureas: a simple access to 2-functionalized indoles

The first asymmetric Michael addition of 1-acetylindolin-3-ones to β-nitrostyrenes has been developed. 2-Substituted indolin-3-one derivatives were obtained with excellent yields (up to 99%) and good stereoselectivities (up to 28:1 dr and 92% ee), which could be transformed into 2-functionalized indoles easily without racemization. This achievement might further contribute to the chemistry and pharmacology of indole-related compounds.     

Enantioselective addition of diethylzinc to aryl aldehydes catalyzed by 1,2,3,4-tetrahydroisoquinoline β-amino alcohol

<正>A highly effective,new chiral 1,2,3,4-tetrahydroisoquinoline catalyst 1 for the diethylzinc addition to aryl aldehydes has been investigated.Using 10 mol%of this chiral catalyst,secondary alcohols can be obtained in up to 87%yield and 99.5%ee under mild conditions.     

Michael addition of indoles to β-nitrostyrenes catalyzed by HY zeolite under solvent-free conditions

Michael addition of indoles to β-nitrostyrenes is reported using HY zeolite as catalyst under mild reaction conditions. This methodology allows the synthesis of various indole derivatives in good to high yields at 50 °C under solvent-free conditions. The short reaction time and achieving high yield of the desired products are the main advantages of the present work. The catalyst can be easily recovered and reused for six successive runs without considerable changes in yields. This Michael addition catalyzed by HY zeolite is operationally simple and can be considered as a greener protocol as it avoids the use of corrosive acids and toxic reagents.     

Enantioselective addition of diethylzinc to aldehydes catalyzed by a new chiral β-amino alcohol derived from d-mannitol

A new chiral β-dialkylamino alcohol 1 prepared from d-mannitol has been used as a highly effective chiral catalyst for the enantioselective addition of diethylzinc to unhindered aliphatic aldehydes to afford the product alcohols in up to 94% ee.     

Asymmetric Michael addition of α-fluoro-α-phenylsulfonyl ketones to nitroolefins catalyzed by phenylalanine-based bifunctional thioureas

Phenylalanine-based bifunctional thiourea derivatives promoted the asymmetric Michael addition of α-fluoro-α-phenylsulfonyl ketones to nitroolefins, affording enantiomerically enriched fluorine-containing multifunctional molecules containing adjoining chiral fluorine-substituted quaternary and tertiary centers in good yields and enantioselectivities.     

Diastereoselective synthesis of β-amino ketone and acid derivatives by palladium-catalyzed conjugate addition

The first diastereoselective synthesis of β-amino ketone and β-amino acid derivatives by palladium-catalyzed conjugate addition of arylboronic acids to chiral β-enamino ketones and β-enamino esters is reported. The catalytic system employing (S)-4-(tert-butyl)oxazolidin-2-one as the chiral auxiliary in water under an air atmosphere provides β-amino ketone and β-amino acid derivatives in high yields with excellent diastereoselectivity.     

Asymmetric Michael addition of boronic acids to a γ-hydroxy-α,β-unsaturated aldehyde catalyzed by resin-supported peptide

A resin-supported peptide catalyst effective for the asymmetric Michael addition of boronic acids to (E)-4-hydroxybut-2-enal was developed. From a spectral study, it was revealed that the optimum peptide consisted of both a β-turn and helix. Such a combination of secondary structures was essential for achieving a high catalytic ability.     

Enantioselective addition of Et_2Zn to aldehydes catalyzed by chi-ral aliphatic β-amino alcohols

This paper describes the preparation of two new optically active aliphatic β-amino alcohols (R)-5,5-dimethyl-2-(dimethy-lamino)-1,1-diphenyl-1-hexanol (1a) and (S)-8,8-dimethyl-2-(dimethylamino)-1, 1-diphenyl-1-nonanol (1b). They were synthesized by methylation of the corresponding β-amino alcohols 2a and 2b. Compounds la and 1b catalyze the addition of diethylzinc to various aldehydes enantioselectively. The catalyst structure-enantioselectivity relationships were discussed.     

Asymmetric organocatalyzed Michael addition of aldehydes to β-nitrostyrene in ionic liquids

The addition of aliphatic aldehydes to β-nitrostyrene, catalyzed by proline-derived organocatalysts, proceeded well in various ionic liquids. Products were obtained in high yields and syn/anti diastereoselectivity. However, the enantioselectivity was only mediocre, even though some analogous reactions in organic solvents were highly enantioselective. We also evaluated the temperature effect on the diastereoselectivity as well as on the enantioselectivity of the Michael addition.     

Water-compatible iminium activation: highly enantioselective organocatalytic Michael addition of malonates to α,β-unsaturated enones

The highly enantioselective Michael addition of malonates to α,β-unsaturated ketones in water was reported to be catalyzed by a primary-secondary diamine catalyst containing a long alkyl chain. This asymmetric Michael addition process was found to be effective for a variety of α,β-unsaturated ketones.     

Asymmetric synthesis of α- and β-amino acids by diastereoselective addition of triorganozincates to N-(tert-butanesulfinyl)imines

The diastereoselective addition of triorganozincates to (R)-N-(tert-butanesulfinyl)imines has been used as a key step to achieve the synthesis of highly enantiomerically enriched N-protected α- and β-amino acids. Desulfinylation of the addition products followed by benzoylation of the nitrogen atom of the obtained primary amines and oxidation of one of the substituents on the carbon atom connected to the nitrogen complete the sequence. Using the same configuration in the sulfinyl chiral auxiliary, α-amino acids with the (R) or the (S) configuration can be prepared by choosing the proper combination of imine and organozincate. α,α-Disubstituted α-amino esters with high enantiomeric purity can also be prepared when α-imino esters are the starting substrates.     

Enantioselective Michael addition of α,α-disubstituted aldehydes to nitroolefins catalyzed by a pyrrolidine-pyrazole

An efficient protocol for the asymmetric catalytic Michael additions of α,α-disubstituted aldehydes to nitroolefins with a pyrrolidine-pyrazole is described. The desired products γ-nitrocarbonyl compounds possessing an all-carbon quaternary center, were obtained in good yields and with high levels of enantioselectivities under solvent-free reaction conditions, employing benzoic acid as an additive.     

Asymmetric Michael addition of α-substituted isocyanoacetates with maleimides catalyzed by chiral tertiary amine thiourea

A highly diastereoselective and enantioselective Michael addition of α-substituted isocyanoacetates with maleimides catalyzed by bifunctional tertiary amine thioureas has been developed. Various chiral succinimide derivatives bearing adjacent quaternary and tertiary stereocenters were prepared in excellent yields (up to 98%), diastereoselectivities (up to 99:1), and enantioselectivities (up to 98% ee). The synthetic utility of chiral succinimide derivatives is also demonstrated in the preparation of h5-HT(1d) receptor agonist motifs.     

Enantio- and diastereoselective Michael addition reactions of α-cyanoketones to nitroalkenes catalyzed by binaphthyl-derived organocatalyst

The catalytic enantioselective and diastereoselective Michael addition reactions promoted by chiral bifunctional organocatalysts are described. The treatment of α-cyanoketones with nitroalkenes under mild reaction conditions afforded the corresponding γ-niro α-cyanoketones with excellent diastereoselectivities (up to syn/anti >99/1) and excellent enantioselectivities (up to 99% ee).     

Enantioselective synthesis of functionalized α-amino acids via a chiral guanidine catalyzed Michael addition reaction

Several chiral guanidines were evaluated as catalysts for the Michael reaction of glycine derivatives 7 with acrylic esters 8. The best result (30.4% ee) was obtained when 7b was reacted with 8b under the catalysis of guanidine 1 in THF.