Organocatalytic Asymmetric Transferhydrogenation of β-Nitroacrylates: Accessing β2-Amino Acids
摘要:
We describe a highly efficient and enantioselective Hantzsch ester mediated conjugate reduction of beta-nitroacrylates that is catalyzed by a Jacobsen thiourea catalyst as a key step in a new route to optically active beta2-amino acids.
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。
Organocatalytic Asymmetric Transferhydrogenation of β-Nitroacrylates: Accessing β<sup>2</sup>-Amino Acids
作者:Nolwenn J. A. Martin、Xu Cheng、Benjamin List
DOI:10.1021/ja8069852
日期:2008.10.22
We describe a highly efficient and enantioselective Hantzsch ester mediated conjugate reduction of beta-nitroacrylates that is catalyzed by a Jacobsen thiourea catalyst as a key step in a new route to optically active beta2-amino acids.
First Iridium-Catalyzed Highly Enantioselective Hydrogenation of β-Nitroacrylates
The first highly chemo- and enantioselective hydrogenation of beta-nitroacrylates was accomplished with an iridium catalyst (Ir-4) with yields and enantioselectivities of up to 96% and 98% ee, respectively. The resulting alpha chiral beta-nitro propionates are attractive building blocks for the synthesis of chiral beta(2)-amino acids, which are the core scaffolds of bioactive natural products, pharmaceuticals, and beta-peptides.
Organocatalytic Enantioselective Michael Reaction of Malononitrile with β,β-Disubstituted Nitroalkenes
optimized an enantioselective Michael reaction of malononitrile with β,β‐disubstituted nitroalkenes. This reaction was catalyzed by a cinchona alkaloid derived thiourea catalyst, producing products of high yields (up to 98 %) and stereoselectivities (up to 93 % ee). One of the adducts was used as an intermediate for the synthesis of dihydropyrrole derivative bearing a synthetically valuable quaternary chiral