Beyond esoteric interest, organocatalysis has now become one major pillar of asymmetric catalysis. Here, we discuss how new activation modes are conquering challenging stereoselective transformations ...and the recent integration of organocatalysis with emerging photo- and electrocatalysis, as well as artificial intelligence.Organocatalysis has become a major pillar of (asymmetric) catalysis. Here, the authors discuss recent trends in organocatalytic activation modes for challenging stereoselective transformations and the emerging integration with other fields, such as photoredox catalysis and electrosynthesis.
Atropisomerism is a stereochemical behavior portrayed by three-dimensional molecules that bear rotationally restricted σ bond. Akin to the well-represented point-chiral molecules, atropisomerically ...chiral compounds are finding increasing utilities in many disciplines where molecular asymmetry is influential. This provides steady demand on atroposelective synthesis, where numerous synthetic pursuits have been rewarded with conceptually novel and streamlined methods while expanding the structural diversity of atropisomers. This review summarizes key achievements in stereoselective preparation of biaryl, heterobiaryl, and nonbiaryl atropisomers documented between 2015 and 2020. Emphasis is placed on the synthetic strategies for each structural class, while examples are cited to illustrate the potential applications of the accessed atropochiral targets.
We present an upgraded version (denoted as version 2.0) of the program HELAC-Onia for the automated computation of heavy-quarkonium helicity amplitudes within non-relativistic QCD framework. The new ...code has been designed to include many new and useful features for practical phenomenological simulations. It is designed for job submissions under cluster environment for parallel computations via Python scripts. We have interfaced HELAC-Onia to the parton shower Monte Carlo programs Pythia 8 and QEDPS to take into account the parton-shower effects. Moreover, the decay module guarantees that the program can perform the spin-entangled (cascade-)decay of heavy quarkonium after its generation. We have also implemented a reweighting method to automatically estimate the uncertainties from renormalization and/or factorization scales as well as parton-distribution functions to weighted or unweighted events. A further update is the possibility to generate one-dimensional or two-dimensional plots encoded in the analysis files on the fly. Some dedicated examples are given at the end of the writeup.
Program title: HELAC-Onia 2.0
Catalogue identifier: AEPR_v2_0
Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEPR_v2_0.html
Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland
Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html
No. of lines in distributed program, including test data, etc.: 1513282
No. of bytes in distributed program, including test data, etc.: 17036140
Distribution format: tar.gz
Programming language: Python, Fortran 77, Fortran 90, C++.
Operating system: Unix-like platform.
Classification: 4.4, 11.1, 11.2, 11.5.
Catalogue identifier of previous version: AEPR_v1_0
Journal reference of previous version: Comput. Phys. Comm. 184(2013)2562
External routines: LHAPDF
Does the new version supersede the previous version?: Yes
Nature of problem: Heavy quarkonium production processes provide an important way to investigate QCD in its poorly known non-perturbative regime. Its production mechanism has attracted extensive interests from the high-energy physics community in decades. The qualitative and quantitative description of heavy-quarkonium production requires complex perturbative computations for high-multiplicity processes in the framework of the well established non-relativistic effective theory, NRQCD, and reliable Monte Carlo simulations to reproduce the collider environment.
Solution method: Based on a recursion relation, the program is able to calculate the helicity amplitudes of the high-multiplicity heavy- quarkonium-production processes. Several modules are also designed for dedicated simulations: 1.The code has been interfaced with the parton shower Monte Carlo programs;2.A decay module to let heavy quarkonia decay with correct spin-correlations has been implemented;3.The code estimates the theoretical uncertainties and analyzes the generated events on the fly;4.The code is compliant with multi-threading/multi-core usage or cluster processors.
Reasons for new version: Improved and expanded functionalities.
Summary of revisions: Many new features were added and several important bugs were fixed. The new features extend the range of the physical applications. With the new interface, it also helps to improve the user-friendliness of the program.
Running time: It depends on the process to be calculated and the required accuracy.
The Ugi reaction constructs α-acylaminoamide compounds by combining an aldehyde or ketone, an amine, a carboxylic acid, and an isocyanide in a single flask. Its appealing features include inherent ...atom and step economy together with the potential to generate products of broad structural diversity. However, control of the stereochemistry in this reaction has proven to be a formidable challenge. We describe an efficient enantioselective four-component Ugi reaction catalyzed by a chiral phosphoric acid derivative that delivers more than 80 α-acylaminoamides in good to excellent enantiomeric excess. Experimental and computational studies establish the reaction mechanism and origins of stereoselectivity.
By the virtues of the Dyson–Schwinger equations, we upgrade the published code HELAC to be capable to calculate the heavy quarkonium helicity amplitudes in the framework of NRQCD factorization, which ...we dub HELAC-Onia. We rewrote the original HELAC to make the new program be able to calculate helicity amplitudes of multi P-wave quarkonium states production at hadron colliders and electron–positron colliders by including new P-wave off-shell currents. Therefore, besides the high efficiencies in computation of multi-leg processes within the Standard Model, HELAC-Onia is also sufficiently numerical stable in dealing with P-wave quarkonia (e.g. hc,b,χc,b) and P-wave color-octet intermediate states. To the best of our knowledge, it is a first general-purpose automatic quarkonium matrix elements generator based on recursion relations on the market.
Program title: HELAC-Onia.
Catalogue identifier: AEPR_v1_0
Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEPR_v1_0.html
Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland
Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html
No. of lines in distributed program, including test data, etc.: 114595
No. of bytes in distributed program, including test data, etc.: 1555550
Distribution format: tar.gz
Programming language: Fortran 90.
Computer: Any.
Operating system: Windows, Unix.
Classification: 4.4, 11.1, 11.2, 11.5.
Nature of problem:
An important way to explore the law of the nature is to investigate the heavy quarkonium physics at B factories and hadron colliders. However, its production mechanism is still unclear, though NRQCD can explain its decay mechanism in a sufficiently satisfactory manner. The substantial K-factor in heavy quarkonium production processes also implies that the associated production of quarkonium and a relatively large number of particles may play a crucial role in unveiling its production mechanism.
Solution method:
A labor-saving and efficient way is to make the tedious amplitudes calculation automatic. Based on a recursive algorithm derived from the Dyson–Schwinger equations, the goal of automatic calculation of heavy quarkonium helicity amplitudes in NRQCD has been achieved. Inheriting from the virtues of the recursion relations with the lower computational cost compared to the traditional Feynman-diagram based method, the multi-leg processes (with or without multi-quarkonia up to P-wave states) at colliders are also accessible.
Running time:
It depends on the process that is to be calculated. However, typically, for all of the tested processes, they take from several minutes to tens of minutes.
N‐arylcarbazole structures are important because of their prevalence in natural products and functional OLED materials. C−H amination of arenes has been widely recognized as the most efficient ...approach to access these structures. Conventional strategies involving transition‐metal catalysts suffer from confined substrate generality and the requirement of exogenous oxidants. Organocatalytic enantioselective C–N chiral axis construction remains elusive. Presented here is the first organocatalytic strategy for the synthesis of novel axially chiral N‐arylcarbazole frameworks by the assembly of azonaphthalenes and carbazoles. This reaction accommodates broad substrate scope and gives atropisomeric N‐arylcarbazoles in good yields with excellent enantiocontrol. This approach not only offers an alternative to metal‐catalyzed C–N cross‐coupling, but also brings about opportunities for the exploitation of structurally diverse N‐aryl atropisomers and OLED materials.
In the frame: Presented here is the first organocatalytic strategy for the synthesis of novel axially chiral N‐arylcarbazole frameworks by the assembly of azonaphthalenes and carbazoles. This reaction accommodates broad substrate scope and gives atropisomeric N‐arylcarbazoles in good yields with excellent enantiocontrol. This approach offers opportunities for the exploitation of structurally diverse N‐aryl atropisomers and OLED materials. CPA=chiral phosphoric acid.
Atropisomeric biaryl motifs are ubiquitous in chiral catalysts and ligands. Numerous efficient strategies have been developed for the synthesis of axially chiral biaryls. In contrast, the asymmetric ...construction of o-quinone-aryl atropisomers has yet to be realized. Inspired by the rapid progress of the chemistry of biaryls, here we present our initial investigations about the atroposelective construction of axially chiral arylquinones by a bifunctional chiral phosphoric acid-catalyzed asymmetric conjugate addition and central-to-axial chirality conversion. With o-naphthoquinone as both the electrophile and the oxidant, three types of arylation counterparts, namely 2-naphthylamines, 2-naphthols and indoles, are utilized to assemble a series of atropisomeric scaffolds in good yields and excellent enantioselectivities. This approach not only expands the axially chiral library but also offers a route to a class of potential, chiral biomimetic catalysts.
Conspectus The growing importance of axially chiral architectures in different scientific domains has unveiled shortcomings in terms of efficient synthetic access and skeletal variety. This account ...describes our strategies in answering these challenges within the organocatalytic context where the emergence of bifunctional catalysts such as chiral phosphoric acids (CPAs) has proven invaluable in controlling the sense of axial chirality. The wide occurrence of bi(hetero)aryl skeletons in privileged structures constitutes a strong motivation to devise more effective arylation methods. Our design revolves around modulating the intrinsic nucleophilicity of aromatic amines and alcohols. The first approach involves the design of an electron-withdrawing activating group which could associate with the catalyst for reactivity enhancement and selectivity control. The resonance of arenes offers the unique mechanistic possibility to select between activating sites. C2-Azo- and nitroso-substituted naphthalenes undergo atroposelective ortho C- or N-arylation with (hetero)aromatic nucleophiles. For monocyclic benzenes, programmable charge localization leads to regioselective activation by catalytic control alone or aided by substrate design. For instance, selective addition to nitroso nitrogen enables successive annulation initiated by the amine to yield axially chiral N-arylbenzimidazoles. In a biomimetic manner, a finely tuned catalyst could direct a para-selective nucleophilic approach in the atroposelective arylation of azobenzenes. The second strategy employs electrophilic arene precursors for arylation which occurs via rearomatization with central-to-axial chirality transfer. This enabled the arylation of (imino)quinones with indoles to access phenylindole atropisomers. By adapting this chemistry with an additional oxidation event to liberate the carbonyl functionalities, aryl-o-naphthoquinone and aryl-p-quinone atropisomers were attained. Along with the development of new arylation strategies, deriving new axially chiral structures has been another consistent theme of our research program. The atroposelective functionalization of alkynes provides broad entry to atropisomeric alkenes. The monofunctionalization of alkynes through the interception of an electrophilic vinylidene-quinone-methide (VQM) intermediate with 2-naphthols yielded the new EBINOL scaffolds. By designing an internal directing group, the atroposelective dihalogenation of alkynes was realized using abundant alkali halides despite their weak nucleophilicities and poor solubilities. The atroposelective N-alkylation of alkenes was pursued to prepare multifunctionalized alkene atropisomers that could be converted into 2-arylpyrroles with chirality transfer. The synthesis of B-aryl-1,2-azaborines containing a C–B chiral axis was accomplished where the CPA catalyst effects the desymmetrization and defines the configuration of the distal C–B bond. Inspired by the axially chiral scaffold of allenes, we leveraged the developed arene activation strategy to achieve para-addition and dearomatization of judiciously designed azobenzenes, which led to structurally novel cyclohexadienylidene-based hydrazones. To complement these structures, axially chiral cyclohexadienyl oxime ethers were also attained through CPA-catalyzed condensation between hydroxylamines and spiro4.5trienones.
•A (3+1)-dimensional generalized nonlinear evolution equation arising in the shallow water waves.•Fusion and fission phenomena of the X-type, Y-type and periodic lump-stripe solitons are ...observed.•Influences of the coefficients of the equation on the periodic lump-stripe soliton solutions are analysed.
Water waves are observed in, e.g., the rivers, lakes or oceans. In this Letter, the investigation is conducted on a (3+1)-dimensional generalized nonlinear evolution equation arising in the shallow water waves. Based on the Hirota method and symbolic computation, we obtain some X-type, Y-type and periodic lump-stripe soliton solutions. For the X-type soliton solutions, we observe the fusion and fission phenomena. For the Y-type soliton solutions, combined with the asymptotic analysis, we observe the fission phenomenon. For the periodic lump-stripe soliton solutions, we observe the fusion phenomenon between the periodic lump and stripe soliton. Periodic lump disappears and is finally swallowed by the stripe soliton during the propagation, which implies that the interaction is inelastic. Furthermore, we analyse the influences of the coefficients of the equation on the periodic lump-stripe soliton solutions.
The well‐defined conformational properties of axially chiral compounds bring extraordinary values to an assortment of bioactive molecules, advanced materials, organocatalysts as well as chiral ...ligands in asymmetric transformations. The demonstrated usefulness and untapped potential of axially chiral structural motifs stimulate increasing efforts to develop novel and efficient approaches for their preparation. In this regard, the chiral phosphoric acids broadly used in asymmetric Brønsted acid catalysis have shown high relevance for atroposelective synthesis as well. Our strong interest in reaction chemistry of atropisomers has established a rewarding research programme in our group. The course of studies will be recounted in this Account, with discussion focused on the use of chiral phosphoric acids to catalyze construction of several key axially chiral structures such as BINAM, BINOL, NOBIN, arylquinones, SPINOL, arylpyrrole analogues and axially chiral alkenes.
What is the most favorite and original chemistry developed in your research group?
Organocatalytic asymmetric arene C—H functionalization.
What is the most important personality for scientific research?
Persistence, smart thinking.
What are your hobbies?
Playing basketball, playing card.
What's your favorite book(s)?
The Ordinary World by the famous Chinese writer Yao Lu.
Who influences you mostly in your life?
My parents and my supervisors Prof. Guofu Zhong and Carlos F. Barbas III.
How do you supervise your students?
I advise my students to work smartly and work hard.
The well‐defined conformational properties of axially chiral compounds bring extraordinary values to an assortment of bioactive molecules, advanced materials, organocatalysts as well as chiral ligands in asymmetric transformations. The demonstrated usefulness and untapped potential of axially chiral structural motifs stimulate increasing efforts to develop novel and efficient approaches for their preparation. In this regard, the chiral phosphoric acids broadly used in asymmetric Brønsted acid catalysis have shown high relevance for atroposelective synthesis as well. Our strong interest in reaction chemistry of atropisomers has established a rewarding research programme in our group. The course of studies will be recounted in this account, with discussion focused on the use of chiral phosphoric acids to catalyze construction of several key axially chiral structures such as BINAM, BINOL, NOBIN, arylquinones, SPINOL, arylpyrrole analogues and axially chiral alkenes.
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