Formal Ir-Catalyzed Ligand-Enabled Ortho and Meta Borylation of Aromatic Aldehydes via in Situ-Generated Imines
摘要:
The ligand-enabled development of ortho and meta C-H borylation of aromatic aldehydes is reported. It was envisaged that while ortho borylation could be achieved using tert-butylamine as the traceless protecting/directing group, meta borylation proceeds via an electrostatic interaction and a secondary interaction between the ligand of the catalyst and the substrate. These ligand substrate electrostatic interactions and secondary B-N interactions provide an unprecedented controlling factor for meta-selective C-H activation/borylation.
Progress toward the total synthesis of 9β-hydroxyvertine: Construction of an advanced quinolizidine intermediate
作者:Thanaphat Thaima、Anthony C. Willis、Stephen G. Pyne
DOI:10.1016/j.tet.2019.130476
日期:2019.9
Progress toward the total synthesis of 9β-hydroxyvertine 2 is described. Our approach involves a Petasis borono-Mannich reaction to assemble a key intermediate A, securing the correct configuration at H-9 and H-10 in the final targeted molecule. Subsequent formation of the quinolizidine framework B allowed the synthesis of an advanced intermediate containing all but the lactonemoiety of 2. Our unsuccessful
Design and enantioselective synthesis of 3-(α-acrylic acid) benzoxaboroles to combat carbapenemase resistance
作者:You-Cai Xiao、Xiao-Pan Chen、Ji Deng、Yu-Hang Yan、Kai-Rong Zhu、Gen Li、Jun-Lin Yu、Jürgen Brem、Fener Chen、Christopher J. Schofield、Guo-Bo Li
DOI:10.1039/d1cc03026d
日期:——
Chiral 3-substituted benzoxaboroles were designed as carbapenemase inhibitors and efficiently synthesised via asymmetric Morita–Baylis–Hillman reaction. Some of the benzoxaboroles were potent inhibitors of clinically relevant carbapenemases and restored the activity of meropenem in bacteria harbouring these enzymes. Crystallographic analyses validate the proposed mechanism of binding to carbapenemases
in situ formed biaryl imine as a substrate. Tolerance of a very wide variety of N-substituents is indicated; this has never previously been disclosed by other reports. Application of this method to synthesis of the natural alkaloid bicolorine, and its derivatives, was also carried out in only three synthetic steps from commercially available compounds.
Strategies for the synthesis of Amaryllidaceae alkaloids, including crinasiadine, trisphaeridine, bicolorine, N-methylcrinasiadine, 5,6-dihydrobicolorine, galanthindole, lycosinine A and lycosinine B were reported. Investigation of optionally synthetic routes to approach bicolorine, 5,6-dihydrobicolorine, trisphaeridine and N-methylcrinasiadine were demonstrated as well. In addition, three structurally
An unprecedented synthesis of N‐heteroaromatics from biaryl aldehydes and NH3 through reagent‐free C−H/N−H cross‐coupling has been developed. The electrosynthesis uses NH3 as an inexpensive and atom‐economic nitrogen donor, requires no oxidizing agents, and allows efficient and regioselective access to a wide range of phenanthridines and structurally related polycyclic N‐heteroaromatic products.
通过无试剂的C / H / N-H交叉偶联,由联芳基醛和NH 3合成了N-杂芳族化合物,这是空前的。电合成使用NH 3作为廉价且原子经济的氮供体,不需要氧化剂,并允许有效且区域选择性地访问各种菲啶和结构相关的多环N-杂芳族化合物。