Organocatalyzed Formal [2 + 2] Cycloaddition of Ketimines with Allenoates: Facile Access to Azetidines with a Chiral Tetrasubstituted Carbon Stereogenic Center
摘要:
An enantioselective organocatalyzed aza-MBH-type reaction of ketimines and allenoates has been developed. The present formal [2 + 2] cycloaddition produces highly functionalized azetidines with a chiral tetrasubstituted carbon stereogenic center in good to excellent yields and high enantioselectivities.
Solvent‐Mediated C3/C7 Regioselective Switch in Chiral Phosphoric Acid‐Catalyzed Enantioselective Friedel‐Crafts Alkylation of Indoles with α‐Ketiminoesters
作者:Yunlong Zhao、Lu Cai、Tongkun Huang、Shanshui Meng、Albert S. C. Chan、Junling Zhao
DOI:10.1002/adsc.201901380
日期:2020.3.17
The first solvent‐mediated tunable C3/C7 regio‐ and enantioselective Friedel‐Crafts alkylation of 4‐aminoindoles with α‐ketimino esters has been developed. This catalysis allows the highly regioselective formation of indole C3 and C7 alkylation products, both in high yields (up to 96%) and excellent enantioselectivities (up to 99% ee). Mechanism study revealed that the hydrogen‐bonding interactions
Highly adequate oxidative esterification of α-carbonyl aldehydes with alkyl halides in TBAI/TBHP mediated system
作者:Pooja L. Bhargude、Jatin J. Lade、Bhausaheb N. Patil、Kamlesh S. Vadagaonkar、Atul C. Chaskar
DOI:10.1080/00397911.2019.1600193
日期:2019.5.19
synthesis of α-ketoesters from alkyl halides and α-carbonyl aldehydes has been reported under metal-free conditions. The present method involves oxidativeesterification of α-carbonyl aldehydes with alkyl halide using TBAI as a promoter and TBHP as an oxidant to form α-ketoesters in good to excellent yields with versatile structural diversity. Use of commercially accessible and inexpensive substrates, broad
I<sub>2</sub>-promoted cross-dehydrogenative coupling of α-carbonyl aldehydes with alcohols for the synthesis of α-ketoesters
作者:A. Sagar、Shinde Vidyacharan、Duddu S. Sharada
DOI:10.1039/c4ra06028h
日期:——
A facile and efficient method for the synthesis of α-ketoesters from alcohols and α-carbonyl aldehydes has been developed at room temperature under metal-free conditions for the first time. Various alcohols and α-carbonyl aldehydes could participate in this reaction to afford the desired products in excellent yields.
The enantioselective direct vinylogous aldolreaction of 3-methyl 2-cyclohexen-1-one with α-ketoesters has been developed. The key to success was the design of a bifunctionalprimary amine-thiourea catalyst that can combine H-bond-directing activation and dienamine catalysis. The simultaneous dual activation of the two reacting partners results in high reactivity while securing high levels of stereocontrol
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。