unprecedented direct and vinylogous Michaeladdition of beta-substituted cyclohexenone derivatives to nitroalkenes proceeding under dienamine catalysis. Besides enforcing high levels of diastereo- and enantioselectivity, chiral primary amine catalysts derived from natural cinchona alkaloids ensure complete gamma-site selectivity: The resulting, highly functionalized vinylogous Michael adducts, having two stereocenters
Enantioselective Michael Reactions of β, β-Disubstituted Nitroalkenes: A New Approach to β<sup>2,2</sup>-Amino Acids with Hetero-Quaternary Stereocenters
An atom-economic organocatalytic asymmetric Michaelreaction of α,β,β-trisubstituted olefins has been successfully developed. The reaction exhibits excellent enantioselectivities under low loading of catalysts, and the conjugate addition products are valuable for the synthesis of novel β2,2-amino acids and β-peptides.
Enantioselective Conjugate Addition of Oximes to Trisubstituted β-Nitroacrylates: An Organocatalytic Approach to β<sup>2,2</sup>-Amino Acid Derivatives
A highly enantioselective organocatalytic intermolecular conjugateaddition of oximes to β-nitroacrylates has been developed. The highly functionalized adducts obtained are valuable precursors for asymmetric synthesis, as demonstrated by the synthesis of β2,2-amino acids and oxazolidin-2-ones.
A sulfa-Michael/aldol cascade reaction of 1,4-dithiane-2,5-diol and α-aryl-β-nitroacrylate has been developed, which allows access to 2,5-dihydrothiophenes bearing a quaternary carbon center in moderate to good yields with high enantioselectivities.
Enantioselective Construction of Consecutive Tetrasubstituted Stereogenic Centers by Reaction of α-Substituted β-Nitroacrylates with Oxazol-5-(4<i>H</i>)-ones Catalyzed by Cinchona Alkaloid Sulfonamide Catalysts
The enantioselective reaction of α-substituted β-nitroacrylates with oxazol-5-(4H)-ones (oxazolones) to construct consecutive tetrasubstituted stereogenic centers was accomplished. A cinchonaalkaloid sulfonamide catalyst afforded products bearing vicinal chiral centers with excellent enantio- and diastereoselectivities. The obtained products were successively converted into various chiral compounds
完成了α-取代的 β-硝基丙烯酸酯与 oxazol-5-(4 H )-ones (oxazolones) 的对映选择性反应,构建连续的四取代立体中心。金鸡纳生物碱磺酰胺催化剂为带有邻位手性中心的产物提供了出色的对映和非对映选择性。将所得产物连续转化为各种手性化合物而不损失其对映体纯度。此外,还进行了密度泛函理论 (DFT) 计算,以阐明观察到的反应立体选择性的机制和起源。