849035-67-2Relevant academic research and scientific papers
Highly Enantioselective Synthesis of Indazoles with a C3-Quaternary Chiral Center Using CuH Catalysis
Ye, Yuxuan,Kevlishvili, Ilia,Feng, Sheng,Liu, Peng,Buchwald, Stephen L.
supporting information, p. 10550 - 10556 (2020/07/27)
C3-substituted 1H-indazoles are useful and important substructures in many pharmaceuticals. Methods for direct C3-functionalization of indazoles are relatively rare, compared to reactions developed for the more nucleophilic N1 and N2 positions. Herein, we report a highly C3-selective allylation reaction of 1H-N-(benzoyloxy)indazoles using CuH catalysis. A variety of C3-allyl 1H-indazoles with quaternary stereocenters were efficiently prepared with high levels of enantioselectivity. Density functional theory (DFT) calculations were performed to explain the reactivity differences between indazole and indole electrophiles, the latter of which was used in our previously reported method. The calculations suggest that the indazole allylation reaction proceeds through an enantioselectivity-determining six-membered Zimmerman-Traxler-type transition state, rather than an oxidative addition/reductive elimination sequence, as we proposed in the case of indole alkylation. The enantioselectivity of the reaction is governed by both ligand-substrate steric interactions and steric repulsions involving the pseudoaxial substituent in the six-membered allylation transition state.
SPECIFIC ORTHO ORIENTATION IN THE VICARIOUS SUBSTITUTION OF HYDROGEN IN AROMATIC NITRO COMPOUNDS WITH CARBANION OF CHLOROMETHYL PHENYL SULFONE
Makosza, M.,Glinka, T.,Kinowski, A.
, p. 1863 - 1868 (2007/10/02)
Vicarious nucleophilic substitution of hydrogen atoms in nitroarenes with chloromethylphenyl sulfone proceeds selectively ortho to the nitro group when carried out in t-BuOK/THF base/solvent system.In the majority of 3-substituted nitrobenzene derivatives substitution occurs at the most hindered position 2.These conditions offer an efficient method of synthesis of 2,6 and 2,3-disubstituted nitrobenzene derivatives.
