Asymmetric Total Synthesis of (+)-21-epi-Eburnamonine Via a Photocatalytic Radical Cascade Reaction

An asymmetric total synthesis of(+)-21-epi-eburnamonine has been achieved.Key features of the synthesis include a visible-light photocatalytic intra-/intramolecular radical cascade reaction to assemble the tetracyclic ABCD ring system,and a highly diastereoselective Johnson-Claisen rearrangement to establish the C20 all-carbon quaternary stereocenter.

Synthesis of 1-(2'-Phenyl)cyclopropyl-2,3-epoxypropan-1-ol as the Radical Precursor for the Kinetic Study of Oxiranylcarbinyl Radical

We have successfully synthesized 1-(2-phenyl)cyclopropyl-2,3-epoxypropan-1-ol 3, which will be applied to the kinetics study of oxiranylcarbinyl radical.

Synthesis of Diverse Oxetane Amino Acids via Visible-Light-Induced Photocatalytic Decarboxylative Giese-Type Reaction

The divergent synthesis of versatile 3,3′-disubstituted oxetane amino acids by utilizing visible-light-induced photocatalytic decarboxylative Giese-type reaction has been demonstrated.3-Methyleneoxetane-derived substrates are readily available in a single-step and highly reactive as radical acceptors,allowing the production of versatile oxetaneγ-andα-amino acids in high yields.A distinct ring strain release-driven radical addition mechanism was preliminarily revealed.The preparative power was further highlighted by the application in the synthesis of oxetane-containing dipeptides and azetidine amino acids,as well as the transformation of the product into novel oxetane-containing spiro-heterocycle pharmacophore.

On-Surface Synthesis of Anthracene-Fused Zigzag Graphene Nanoribbons from 2,7-Dibromo-9,9′-bianthryl Reveals Unexpected Ring Rearrangements

On-surface synthesis has emerged as a powerful strategy to fabricate unprecedented forms of atomically precise graphene nanoribbons(GNRs).However,the on-surface synthesis of zigzag GNRs(ZGNR)has met with only limited success.Herein,we report the synthesis and on-surface reactions of 2,7-dibromo-9,9′-bianthryl as the precursor towardπ-extended ZGNRs.Characterization by scanning tunneling microscopy and high-resolution noncontact atomic force microscopy clearly demonstrated the formation of anthracene-fused ZGNRs.Unique skeletal rearrangements were also observed,which could be explained by intramolecular Diels-Alder cycloaddition.Theoretical calculations of the electronic properties of the anthracene-fused ZGNRs revealed spin-polarized edge-states and a narrow bandgap of 0.20 eV.

First total synthesis of 10α-hydroxy-4-muurolen-3-one and its C_(10)-isomer

An efficient synthetic route to muurolane type sesquiterpenes starting from （R）-carvone, employing allylic diazene rearrangement and the ring closing methesis （RCM） reaction as key steps, is described. The first asymmetric total synthesis of （-）-10α- hydroxy-4-muurolen-3-one 11 and （-）-10β-hydroxy-4-muurolen-3-one C was accomplished. Through the total synthesis, the absolute configurations of the natural products A, B and C were established.

Effect of chloralkanes on the phenyltrichlorosilane synthesis by gas phase condensation

To enhance the process of phenyltrichlorosilane synthesis using gas phase condensation, a series of chloralkanes were introduced. The influence of temperature and chloralkane amount on the synthesis was studied based on the product distribution from a tubular reactor. The promoting effect of chloralkane addition was mainly caused by the chloralkane radicals generated by the dissociation of C–Cl bond. The promoting effect of the chloromethane with more chlorine atoms was better than those with less chlorine atoms. Intermediates detected from the reactions with isoprene and bromobenzene demonstrated that both trichlorosilyl radical and dichlorosilylene existed in the reaction system in the presence of chloralkanes. A detailed reaction scheme was proposed.

Advances of radical and photo reactions in natural products synthesis

This review will focus on the recent advances of radical and photo reactions and their applications in the natural products total synthesis. A brief introduction to the development and mechanism of the newly developed radical and photo reactions will be presented. The organization of the each section is based on the type of reactions used. Examples of synthetic applications are discussed to demonstrate the potential of related methodologies and inspire future explorations.

Bioinspired synthesis of cochlearol B and ganocin A

Described here is a divergent,biosynthetically inspired synthesis of cochlearol B and ganocin A.Key steps of the synthesis include the chromene unit construction through a biomimetic acid-catalyzed[4+2]ring cyclization.A photochemical[2+2]cycloaddition was featured to construct the cyclobutane core of cochlearol B.Different skeletal rearrangements of cochlearol B afforded ganocin A,that one of them was Lewis acid mediated epoxide rearrangement and another was DDQ induced cyclobutane formed tetrahydrofuran ring.The described syntheses not only achieved these natural products in an efficient manner,but also provided insight into the biosynthetic relationship between the two different skeletons.

Efficient and collective total synthesis of natural products via radical cascade reactions

Subject Code:B02With the support of the National Natural Science Foundation of China,the research team led by Prof.Qin Yong(秦勇)at Sichuan University accomplished a collective synthesis of 33 monoterpenoid indole alkaloids that belong to four families,by developing new photoredox-initiated radical cascade reactions.

Construction of axially chiral compounds via catalytic asymmetric radical reaction

The chemistry of axially chiral compounds has emerged as a subject of increasing interest due to their widespread presence in natural products,bioactive molecules,advanced materials,and chiral ligands/catalysts.On the other hand,catalytic asymmetric radical-based transformations provide a complementary platform for the construction of enantiomerically enriched molecules that are in growing demand in the chemical and pharmaceutical in-dustries.In recent years,considerable research efforts have been devoted to the development of catalytic asymmetric radical reactions for the construction of axially chiral compounds based on the unique reactivity modes of diverse radicals.In this review,we critically illustrate these recent achievements according to different radical precursors and catalytic activation modes.Wherever possible,special emphasis is also placed on the discussion of mechanistic features underlying these works and substrate scopes.This review should be of great interest to the experts in this area,but also serve as a helpful starting point for new researchers in this field.

Modular synthesis of 1,4-diketones through regioselective bis-acylation of olefins by merging NHC and photoredox catalysis

Efficient and modular synthesis of structurally diverse 1,4-diketones from readily available building blocks represents an essential but challenging task in organic chemistry.Herein,we report a multi-component,regioselective bis-acylation of olefins by merging NHC organocatalysis and photoredox catalysis.With this protocol,a broad range of 1,4-diketones could be rapidly assembled using bench-stable feedstock materials.The robustness of this method was further evaluated by sensitivity screening,and good reproductivity was observed.Moreover,the diketone products could be readily converted into functionalized heterocycles,such as multi-substituted furan,pyrrole,and pyridazine.Mechanistic investigations shed light on the NHC and photoredox dual catalytic radical reaction mechanism.

新型磺酰基吲哚萘醌类化合物的合成及其光物理性质

醌类化合物是一类具有独特生物活性和光物理性质的重要化合物。以吲哚萘醌和磺酰基肼为底物,经历碘化亚铜/过氧化叔丁醇介导的氧化自由基历程,简单、高效地以22%~67%的收率获得了8种取代的磺酰基醌类化合物(6a~6h),产物结构经过^(1)H NMR,^(13)C NMR和HR-MS(ESI)表征。初步探究了化合物6a~6h的光物理性质,结果表明:可以通过不同位置的取代基的变换来调节化合物的最大紫外吸收波长和荧光发射强度。

Machine Learning Prediction of Structure-Performance Relationship in Organic Synthesis

Data-driven approach has emerged as a powerful strategy in the construction of structure-performance relationships in organic synthesis.To close the gap between mechanistic understanding and synthetic prediction,we have made efforts to implement mechanistic knowledge in machine learning modelling of organic transformation,as a way to achieve accurate predictions of reactivity,regio-and stereoselectivity.We have constructed a comprehensive and balanced computational database for target radical transformations(arene C—H functionalization and HAT reaction),which laid the foundation for the reactivity and selectivity prediction.Furthermore,we found that the combination of computational statistics and physical organic descriptors offers a practical solution to build machine learning structure-performance models for reactivity and regioselectivity.To allow machine learning modelling of stereoselectivity,a structured database of asymmetric hydrogenation of olefins was built,and we designed a chemical heuristics-based hierarchical learning approach to effectively use the big data in the early stage of catalysis screening.Our studies reflect a tiny portion of the exciting developments of machine learning in organic chemistry.The synergy between mechanistic knowledge and machine learning will continue to generate a strong momentum to push the limit of reaction performance prediction in organic chemistry.

铜(Ⅰ)催化氧化无溶剂合成苯并吖啶二酮衍生物

建立了一种苯并吖啶二酮衍生物的绿色合成方法,以2-(苯基氨基)萘-1,4-二酮类化合物与氰乙酸乙酯为原料,在铜(Ⅰ)与绿色氧化剂过氧叔丁醇的催化氧化体系下,通过无溶剂的自由基串联反应合成9个苯并吖啶二酮衍生物3a~3i,收率72%~79%.该合成策略绿色环保、操作简单(萃取和洗涤,无柱色谱分离)、原料简单易得,为高效合成具有潜在生物活性的苯并吖啶二酮衍生物提供了新的途径.

Studies toward the Synthesis of （R）-（＋）-Harmicine

The study toward the total synthesis of （R）-（＋）-harmicine is reported in this paper. The enantioselective syn- thesis of pyrrolidinone, the main backbone of of （R）-（＋）-harmicine, has been completed by the methodology based on photo-induced Wolff rearrangement of α-diazo-β-carbonyl compounds.

An Efficient Synthesis of 3,3＇,4,4＇-Tetrahydro-4,4＇-bibenzo- [e][1,3]oxazine-2,2＇-dione Derivatives with the Aid of Low-valent Titanium

Synthesis of 3,3＇,4,4＇-tetrahydro-4,4＇-bibenzo[e][1,3]oxazine-2,2＇-diones via reaction of salicylidendphenylhy- drazone and triphosgene with the aid of low-valent titanium reagent is described. This method has the advantages of accessible starting materials, good yields and short reaction time.

Synthetic studies towards(-)-deserpidine:Total synthesis of the stereoisomer and derivative of (-)-deserpidine

The asymmetric synthesis of 16,17,20-epi-deserpidine and a derivative of(-)-deserpidine has been achieved.Key feature s in the assembly of the pentacyclic framework include a visible-light photocatalytic intra-/inter-/intramolecular radical cascade reaction to construct the tetracyclic ABCD ring system in one-pot and an intramolecularaldol reaction to forge the cyclohexane E ring.

绿色合成融入化学实验教学—光催化制备呋喃

当前医科院校有机化学实验普遍缺乏绿色合成理念的介绍,而且通常需要用到强酸、高温等苛刻反应条件。将绿色合成融入实验教学是一种必然趋势。可见光是一种绿色无污染能源。我们为药学类专业有机化学实验课程设计了一个光催化自由基串联反应的教学实验,以(1-氟乙烯基)苯与2-溴苯乙酮作为原料,在可见光照射下合成呋喃衍生物。本实验具有步骤经济性、条件温和、环境友好等优点,非常适合本科生实验教学和创新型人才的培养。

自由基协助的C-H键官能团化反应研究进展

过去几十年中,过渡金属催化的碳氢键官能团化反应研究取得了重要进展。最近,自由基协助的碳氢键官能团化反应正逐渐引起化学工作者的兴趣。依据自由基产生方式,本文分为光、热致自由基协助碳氢键官能团化反应和电致自由基协助碳氢键官能团化反应两个部分,随后在各部分按照成键类型进行论述。综合比较上述两类自由基协助的碳氢键官能团化研究成果,相较于光、热致自由基协助的碳氢键官能团化反应,电致自由基反应有效避免了前者的缺陷,因此发展电化学碳氢键活化反应是自由基协助的碳氢键官能团化反应的重要研究方向。

2-异丙基-1,3-二氢-4(1H)异喹啉酮及其衍生物的合成

异喹啉酮 (1)与羟胺反应得异喹啉酮肟 (2 ) ,再经Schroeter重排合成得到 4 氨基异喹啉的盐 (3) ,进而经催化加氢还原生成其脱烷基产物 6 .另外 ,异喹啉酮与NaN3 反应合成得到苯并二氮杂酮 (4 ) ,4经还原可生成苯并二氮杂 (5 ) .合成得到的 5个新化合物的结构经元素分析、红外。