Cu-Catalyzed Aromatic Metamorphosis of 3-AminoindazolesSubmitted by Jun Zhu on Thu, 09/12/2019 - 08:54
We present a novel Cu-catalyzed aromatic metamorphosis of 3-aminoindazoles via oxidative cleavage of two C–N bonds of 3-aminoindazoles. This unprecedented reactivity of 3-aminoindazoles allows one to forge diverse nitrile-containing triphenylenes in decent yields via generation of the cyano group in situ. The current study reveals that 3-aminoindazoles could be harnessed as radical precursors via oxidative denitrogenation, the reaction mechanism of which was supported by density functional theory calculations.
Reaction Mechanisms on Unusual 1,2‐Migrations of N‐Heterocyclic Carbene‐Ligated Transition Metal ComplexesSubmitted by Jun Zhu on Thu, 09/05/2019 - 10:46
Unusual 1,2‐migration reactions of N‐heterocyclic carbene (NHC) on transition metals were investigated using density functional theory calculations. Our results reveal that the electronic properties, ring strain of the four‐membered ring, and aromaticity of NHC play crucial roles in the thermodynamics of such a 1,2‐migration.
Bowl Inversion in an Exo‐type Supramolecule in the Solid StateSubmitted by Jun Zhu on Wed, 08/14/2019 - 09:34
Bowl inversion is a unique property of buckybowls. The polarity and assembly configuration of buckybowls are reversed after bowl inversion. So far, this unique phenomenon has been studied in solution and on surface, but not in solid state due to spatial constraint. Now a series of exo‐type supramolecular assemblies of trithiasumanene and nanographene are investigated. Tuning the electron density of the nanogaphene component was found to directly affect the binding constant of the complex.
3‐Aminoindole Synthesis from 2‐Nitrochalcones and Ammonia or Primary AminesSubmitted by Jun Zhu on Wed, 07/03/2019 - 21:26
A step‐economic strategy for 3‐aminoindoles synthesis with ammonia or primary amines as “N” source under transition‐metal‐free conditions was achieved. A series of 3‐aminoindoles was obtained with abundant “N” source featuring high efficiency, mild conditions, environmental friendliness and scalability. Efficient syntheses of the intermediates of COX‐2 inhibitor and tubulin polymerization inhibitor were successfully accomplished with this newly developed strategy.
Probing Reaction Mechanism of [1,5]‐Migration in Pyrrolium and Pyrrole Derivatives: Activation of a Stronger Bond in Electropositive Groups Becomes EasierSubmitted by Jun Zhu on Wed, 07/03/2019 - 14:23
The [1,5]‐migration reaction has attracted considerable attention from experimentalists and theoreticians for decades. Although it has been extensively investigated in various systems, studies on pyrrolium derivatives are underdeveloped. Herein, a theoretical study on the reaction mechanism of [1,5]‐migration in both pyrrolium and pyrrole derivatives is presented.
Aromaticity‐promoted C−F Bond Activation in Rhodium Complex: A Facile TautomerizationSubmitted by Jun Zhu on Sun, 05/12/2019 - 23:19
Fluorine is the most electronegative element in the periodic table. Thus, activation of the carbon–fluorine (C−F) bond, the strongest single bond to carbon, has attracted considerable interest from both experimentalists and theoreticians. In comparison with numerous approaches to activate C−F bonds, the aromaticity‐promoted method is less developed. Herein, we demonstrate that the C−F bond activation could be achieved by a facile tautomerization, benefitting from aromaticity, which can stabilize both the transition states and products.
Unconventional Aromaticity in Organometallics: The Power of Transition MetalsSubmitted by Jun Zhu on Sun, 05/12/2019 - 23:10
Aromaticity, one of the most fundamental concepts in chemistry, has attracted considerable attention from both theoreticians and experimentalists. Much effort on aromaticity in organometallics has been devoted to metallabenzene and derivatives. In comparison, aromaticity in other organometallics is less developed. This Account describes how our group has performed quantum chemical calculations to examine aromaticity in recently synthesized novel organometallic complexes.
Dual Aromaticity in Both the T0 and S1 States: Osmapyridinium with Phosphonium SubstituentsSubmitted by Jun Zhu on Thu, 03/21/2019 - 14:02
According to Hückel’s and Baird’s rules, cyclic conjugated species are aromatic either in the ground state or in the excited state only. Thus, species with aromaticity in both states (denoted as adaptive aromaticity) are particularly rare. Here we carry out density functional theory calculations on a series of osmapyridine and osmapyridinium complexes (96 species) and find that two of them display adaptive aromaticity, which was verified by various aromaticity indices including HOMA, ELFπ, MCI, ACIDπ plots and the heat of hydrogenation.
Bonded to Carbon or Nitrogen? This is a Question on the Regioselectivity in Hyperconjugative AromaticitySubmitted by Jun Zhu on Sun, 03/17/2019 - 19:12
In chemistry, regioselectivity is the preference of one direction of chemical bond making or breaking over all other possible directions. Although it has been extensively investigated in various reactions, the regioselectivity of hyperconjugative aromaticity on either main group systems or transition metal ones remains elusive due to the challenge of synthesizing the target products. Here we report a joint theoretical and experimental study on this issue.
Rational Design of a Carbon–Boron Frustrated Lewis Pair for Metal‐free Dinitrogen ActivationSubmitted by Jun Zhu on Fri, 02/22/2019 - 09:52
Molecular nitrogen (N2) is abundant in the atmosphere and nitrogen, found in many biomolecules, is an essential element of life. The Haber–Bosch process, developed over 100 years ago, requires relatively harsh conditions to activate N2 on the iron surface and generate ammonia for use as fertilizer or to produce other chemicals, leading to consumption of more than 2% of the world’s annual energy supply. Thus, developing approaches for N2 activation under mild conditions is particularly important and urgent.