Highly enantio- and diastereoselective Michael addition of cyclohexanone to nitroolefins catalyzed by a chiral glucose-based bifunctional secondary amine-thiourea catalyst
A novel bifunctional thiourea bearing a saccharide-scaffold and a secondary amino group was synthesized, and was proven to be an effective organocatalyst for the asymmetric Michael reaction of cyclohexanone to both aryl and alkyl nitroolefins. The corresponding adducts were obtained with excellent diastereo- (up to >99/1 dr) and enantioselectivities (up to 97% ee).
Primary Amine-Thioureas with Improved Catalytic Properties for “Difficult” Michael Reactions: Efficient Organocatalytic Syntheses of (S)-Baclofen, (R)-Baclofen and (S)-Phenibut
作者:Michail Tsakos、Christoforos G. Kokotos、George Kokotos
DOI:10.1002/adsc.201100636
日期:2012.3
Among the class of primary amine‐thioureas based on tert‐butyl esters of α‐amino acids, the most efficient organocatalyst for “difficult” Michaelreactions was identified. The derivative based on (S)‐di‐tert‐butyl aspartate and (1R,2R)‐diphenylethylenediamine provided the products of the reaction between aryl methyl ketones and nitroolefins in excellent yields and enantioselectivities. In addition
4-Aminothioureaprolinal dithioacetal 4a is a highlyefficientcatalyst for the asymmetric Michaeladdition of ketones and aldehydes to nitroolefins requiring only 3 mol-% catalyst loading. The reactions proceeded smoothly and gave syn selective adducts with excellent yields (up to 98 % yield), diastereoselectivity (up to >99:1 dr), and enantioselectivity (up to 99 % ee) under solvent free conditions
Enantioselective Conjugate Addition of Both Aromatic Ketones and Acetone to Nitroolefins Catalyzed by Chiral Primary Amines Bearing Multiple Hydrogen-Bonding Donors
of chiral primary amine catalysts bearing multiple hydrogen-bonding donors have been designed and synthesized. The newly developed bifunctional organocatalysts efficiently catalyzed not only enantioselectiveconjugateaddition of aromatic ketones to nitroolefins in good yields (up to 87%) with excellent enantioselectivities (97→99% ee) but also enantioselectiveconjugateaddition of acetone to nitroolefins
A polystyrene-supported 9-amino(9-deoxy)epi quinine derivative for continuous flow asymmetric Michael reactions
作者:Javier Izquierdo、Carles Ayats、Andrea H. Henseler、Miquel A. Pericàs
DOI:10.1039/c5ob00325c
日期:——
derivative catalyzes Michael reactions affording excellent levels of conversion and enantioselectivity using different nucleophiles and structurally diverse enones. The highly recyclable, immobilized catalyst has been used to implement a single-pass, continuous flow process (residence time: 40 min) that can be operated for 21 hours without significant decrease in conversion and with improved enantioselectivity