Direct Asymmetric Michael Addition Research Articles

Direct asymmetric Michael addition of thioether-based aryl sulfanyl-propan-2-one to nitroalkenes catalyzed by a chiral amine-thiourea bifunctional organocatalyst

Although the organocatalytic direct asymmetric Michael reactions of carbonyl compounds to nitroalkenes have been investigated intensely, the Michael reaction of the thioether-based donors remains a rather undeveloped field. This work concerns the asymmetric Michael addition of aryl sulfanyl-propan-2-one to nitroalkenes with benzoic acid as an additive, and chiral amine-thiourea as a bifunctional organocatalyst. The reactions provided the highly functionalized chiral adducts with excellent enantioselectivities (up to 96% ee) and good yields. Moreover, the further transformed products exhibited excellent diastereoselectivity.

ChemInform Abstract: Novel Prolinamide—Camphor‐Containing Organocatalysts for Direct Asymmetric Michael Addition of Unmodified Aldehydes to Nitroalkenes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Novel Prolinamide–Camphor‐Containing Organocatalysts for Direct Asymmetric Michael Addition of Unmodified Aldehydes to Nitroalkenes

Novel Prolinamide–Camphor‐Containing Organocatalysts for Direct Asymmetric Michael Addition of Unmodified Aldehydes to Nitroalkenes

Self-Assembled Organocatalysts

The use of self-assembled organocatalysts composed of α-amino acids and alkaloids in the direct asymmetric Michael addition of ketones and aldehydes to aromatic nitroolefins is reported. Ionic interactions between the ammonium and the carboxylate cause the two modules to self-assemble (see general concept). l-Phenylglycine together with quinidine derivative 2 carrying a thiourea moiety afforded the highest asymmetric induction. The assembly of l -proline and 2 was in certain cases less enantioselective, but more active. The authors observed strong matching and mismatching effects between the two catalyst modules.

2‐[(Imidazolylthio)methyl]pyrrolidine as a Trifunctional Organocatalyst for the Highly Asymmetric Michael Addition of Ketones to Nitroolefins

AbstractThe direct asymmetric Michael addition of ketones to nitroolefins catalyzed by 2‐[(imidazol‐2‐ylthio)methyl]pyrrolidine, constructed from natural L‐proline and imidazolylthio platforms, with salicylic acid as a co‐catalyst has been developed to give the products in high yields (up to 95 %) and with excellent enantioselectivities (up to 99 % ee). The highly efficient catalytic performance may be attributed to the dual activation of the Michael substrates by the trifunctional organocatalysts and the co‐catalyst salicylic acid, leading to the formation of a stable transition state complex through the synergic effect of hydrogen‐bonding and electrostatic interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

4,4′‐Disubstituted‐L‐proline Catalyzes the Direct Asymmetric Michael Addition of Aldehydes to Nitrostyrenes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

4,4′‐Disubstituted‐L‐proline Catalyzes the Direct Asymmetric Michael Addition of Aldehydes to Nitrostyrenes

AbstractIn a search for small organic molecules as catalysts for the direct asymmetric Michael addition reaction of aldehydes to nitrostyrenes, 4,4′‐di(naphthalene‐1‐ylmethyl)‐L‐proline 1c and a catalytic amount of 4‐dimethylaminopyridine (DMAP) were found to be an efficient system for the Michael addition of aldehydes to nitrostyrenes with high diastereo‐ and enantioselectivity and broad substrate range.

Effective and Recyclable Dendritic Catalysts for the Direct Asymmetric Michael Addition of Aldehydes to Nitrostyrenes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Effective and recyclable dendritic catalysts for the direct asymmetric Michael addition of aldehydes to nitrostyrenes

Direct catalytic enantio- and diastereoselective Michael addition reaction of aldehydes to nitrostyrenes is described using a series of recyclable chiral 2-trimethylsilanyloxy-methyl-pyrrolidine-based dendritic catalysts. Good yields (up to 82%), and high diastereoselectivities (up to syn/ anti = 95/5) and enantioselectivities (up to 99% ee) have been obtained.