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1.
Organocatalytic asymmetric Michael addition of 3-(OTBS)-propanal to β-nitrostyrenes catalyzed by chiral sulfamides was investigated. Good d.r. (up to 80:20) and excellent enantioselectivities (up to >99% ee) were achieved. Both the N-[(1R,2R)-2-aminocyclohexyl]-N’-(phenylmethyl)sulfamide 7b and the novel chiral N-[(1R,2R)-2-aminocyclohexyl]-N’-[3,5-bis(trifluoromethyl)phenyl]sulfamide 7a were identified as efficient primary amine organocatalysts.  相似文献   

2.
A type of secondary-secondary-tertiary triamine bifunctional organocatalysts have been properly designed and synthesized. In our study, the designed catalyst (S)-N-(pyrrolidin-2-ylmethyl)pyridin-2-amine 5 has been shown to be highly efficient to promote the asymmetric Michael addition of ketones to nitroolefins at room temperature, which afforded the corresponding adducts in excellent diastereoselectivities (up to 99:1 dr) and enantioselectivities (up to >99% ee).  相似文献   

3.
Chiral primary amine thiourea catalysts were first successfully applied to promote Michael addition of isobutyraldehyde to maleimides. A variety of N-aryl and N-aliphatic maleimides provided Michael adducts in excellent yields (up to 98%) and enantioselectivities (up to 99% ee) with 5 mol % catalyst.  相似文献   

4.
《Tetrahedron: Asymmetry》2007,18(12):1443-1447
A new type of catalyst for the asymmetric Michael addition reaction has been designed and synthesized. This catalyst, (S)-pyrrolidine arenesulfonamide 1, resulted in high yields (up to 93%), excellent diastereoselectivities (syn/anti ratio up to 99/1), and excellent enantioselectivities (ee up to 99%) for various cyclic ketones and nitroolefins.  相似文献   

5.
Two chiral ammonium ionic liquids 1a and 1b have been newly synthesized from commercially available (+)-cis-2-benzamidocyclohexanecarboxylic acid. These CILs have been demonstrated to be efficient organocatalysts for asymmetric Michael addition of aldehydes to nitroolefins with excellent yields (up to 99%), high enantioselectivities (up to 90%) and modest to high diastereoselectivities (syn/anti ratio up to 99/1).  相似文献   

6.
Jia-Long Hu  Feng Sha  Qiong Li  Xin-Yan Wu 《Tetrahedron》2018,74(50):7148-7155
A highly enantioselective Michael/cyclization tandem reaction between dimedone and isatylidene malononitriles has been developed. With 5?mol% of bifunctional organocatalyst C15, chiral spiro[2-amino-4H-pyran-oxindole] derivatives were obtained in excellent yields (97–99%) with excellent enantioselectivities (up to?>?99% ee).  相似文献   

7.
A highly enantioselective Michael addition of nitro esters to 2-enoyl-pyridine N-oxides was developed by using chiral copper catalysts. The Michael addition products can be obtained in high yields and with up to 96% ee.  相似文献   

8.
Qing Gu 《Tetrahedron》2009,65(27):5265-2296
Highly enantioselective Michael reaction of acetone with a variety of nitroolefins catalyzed by N-[(1R,2R)-2-aminocyclohexyl]-N′-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)-thiourea (1b) together with acetic acid is described. The Michael addition products were obtained in high yields (76-94%) and up to 96% ee.  相似文献   

9.
Domino Michael reactions of oxophorone and its derivatives 4 with Michael partners 3 have been effected to give bicyclo[2.2.2]octane-2,5-dione derivatives 7 by a catalytic amount of a Brønsted base (NMAP-Li) generated from N-methylaminopropylated silica gel (NMAP) and n-BuLi. The NMAP pellets were efficiently reused up to six times in 86% average yield.  相似文献   

10.
A direct asymmetric Michael addition of cyclic 1,3-dicarbonyl compounds to β,γ-unsaturated α-ketoesters could be efficiently catalyzed by an N,N′-dioxide-nickel(II) complex. A series of chiral warfarin derivatives were obtained in excellent yields (up to 99%) with high enantioselectivities (up to 90% ee) under mild conditions within shorter reaction time.  相似文献   

11.
A new class of pyrrolidine-based functionalized chiral ionic liquids (FCILs) has been developed and shown to be effective and reusable catalysts for the asymmetric Michael addition reactions. For the Michael addition reaction involving various aldehydes and nitrostyrenes, FCIL 6, in combination with trifluoroacetic acid as an additive, was found to be a very effective catalyst, compared to FCIL 3, which varied slightly in structure. Excellent yields (up to 99%), good enantioselectivities (up to 85% ee), and high diastereoselectivities (syn/anti ratio up to 97:3) were obtained for these reactions. The FCIL catalysts were easily recycled and reused for at least five times without significantly losing their ability to affect the outcome of the asymmetric reactions.  相似文献   

12.
A simple and convenient strategy was developed to synthesize a new class of pyrrolidinyl-camphor based bifunctional organocatalysts possessing varying functional linkers. Catalytic screening of these camphor-pyrrolidine linked derivatives for asymmetric Michael reaction of cyclohexanone with β-nitrostyrene was carried out. Various aryl- and heteroaryl-nitroolefins, ketones as well as aldehydes gave the corresponding Michael adducts in high chemical yields (up to 95%) and exceptionally high diastereo-(syn/anti up to 99:1) and enantioselectivity (up to 95%) using catalyst 6 under solvent-free conditions.  相似文献   

13.
The first copper-catalyzed enantioselective addition of alcohols to imines was described. In the presence of 1?mol% Cu(OAc)2 complexed with chiral cyclohexane-based N,P-ligand L4, chiral isatin-derived N,O-aminals were obtained in excellent yields (93–99%) and good-to-excellent enantioselectivities (up to 93% ee) under mild conditions.  相似文献   

14.
Chao Wang 《Tetrahedron letters》2009,50(20):2363-2296
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 (-CH2OTBDPS) and the sulfonamido group at the 4-position of the pyrrolidine ring was important to achieve high yield and stereoselectivity.  相似文献   

15.
《Tetrahedron: Asymmetry》2014,25(4):327-333
First synthesis of C2-symmetric chiral O,N,N,O-tetradentate 2,2-bipyridyldiolpropane ligands is described. The Mukaiyama–Michael reaction was applied as an important reaction for the synthesis of 2,2-bipyridylpropane 9. Among the ligands synthesized, ligand 11 exhibits excellent chiral induction (up to 97% ee) in diethylzinc addition to various aldehydes. The use of additional Lewis acid such as Ti(OiPr)4 in diethylzinc addition reaction is not required for the present catalytic system.  相似文献   

16.
A comparison of three different catalytic systems for the efficient, asymmetric synthesis of N-({(3R,4R)-4-[(benzyloxy)methyl]pyrrolidin-3-yl}methyl)-N-(2-methylpropyl)benzenesulfonamide 1 (BZN) is described. The presented strategy is based on the organocatalytic Michael addition of aldehyde 2 to trans-nitroalkene 3, and subsequent reductive cyclization. High yields, enantio-, and diastereoselectivities were achieved in the Michael addition by application of a POSS- or Wang resin-supported Hayashi–Jørgensen catalyst.  相似文献   

17.
A novel category of di(N,N-dimethylbenzylamine)prolinol silyl ether catalyst, which when used in conjunction with an acidic co-catalyst, generates an ammonium salt supported organocatalyst. This catalytic system is shown to be very effective for the Michael reaction of benzyloxyacetaldehyde and various nitroolefins in isopropanol. Excellent enantioselectivities (up to 99%) and diastereoselectivities (syn/anti of 75:25) and short reaction times were obtained. The presence of the bulky OTMS group combined with the presence of two large N,N-dimethylbenzyl ammonium ion groups accounts for the effectiveness of this catalytic system.  相似文献   

18.
Maria Irene Donnoli 《Tetrahedron》2004,60(23):4975-4981
Both enantiomers of the trans stereoisomer of magnolione 4 have been prepared by asymmetric Michael addition of ethyl acetoacetate to 2-pentylcyclopentenone, followed by hydrolysis/decarboxylation. The Michael reaction occurs under solid/liquid phase transfer catalysis in the presence of N-methylanthracenylquininium (or quinidinium) chloride. Enantiomeric excesses up to 76% are obtained. The trans structure of the compounds has been fully established by a careful NMR analysis, while the absolute configuration has been assigned as (2S,3S) for (+)-4 by the analysis of the CD spectrum.  相似文献   

19.
《Tetrahedron: Asymmetry》2007,18(11):1308-1312
l-Proline derived triamine 4 has been developed as a highly efficient and stereoselective organocatalyst for the asymmetric Michael addition of cyclohexanone to nitroolefins. In the presence of (CF3SO2)2NH, 4 catalyzed the reaction of cyclohexanone to a variety of nitroolefins with high yields (up to 99%) and excellent diastereoselectivities (up to 99:1 dr) and enantioselectivities (up to 98% ee).  相似文献   

20.
An efficient diastereo- and enantioselective Michael addition of α-substituted isocyanoacetates to N-aryl maleimides catalyzed by quinine or cyclohexane-1,2-diamine derived squaramide catalysts has been disclosed, affording the corresponding adducts in good yields (up to 99%), high diastereoselectivities (up to >20:1 dr) and good to excellent enantioselectivities (up to 94% ee) under mild conditions.  相似文献   

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