scholarly journals Modular Synthesis of Functionalized Butenolides by Oxidative Furan Fragmentation

2019 ◽  
Author(s):  
Jiajing Bao ◽  
Hailong Tian ◽  
Peicheng Yang ◽  
Jiachen Deng ◽  
Jinghan Gui
Keyword(s):  
Research Effort ◽  
Value Added ◽  
Building Blocks ◽  
Biologically Active ◽  
Coupling Reactions ◽  
Chemical Transformations ◽  
Modular Synthesis ◽  
Cross Coupling Reactions ◽  
Radical Trapping ◽  
Radical Fragmentation

The development of new chemical transformations to simplify the synthesis of valuable building blocks is a challenging task in organic chemistry and has been the focus of considerable research effort. From a synthetic perspective, it would be ideal if the natural reactivities of feedstock chemicals could be diverted to the production of high value-added compounds which are otherwise tedious to prepare. Here we report a chemical transformation that enables facile and modular synthesis of synthetically challenging yet biologically important functionalized butenolides from easily accessible furans. Specifically, Diels–Alder reactions between furans and singlet oxygen generate versatile hydroperoxide intermediates, which undergo iron(II)-mediated radical fragmentation in the presence of Cu(OAc)<sub>2</sub> or various radical trapping reagents to afford butenolides bearing a wide variety of appended remote functional groups, including olefins, halides, azides and aldehydes. The practical utility of this transformation is demonstrated by easy diversification of the products by means of cross-coupling reactions and, most importantly, by its ability to simplify the syntheses of known building blocks of eight biologically active natural products.

scholarly journals Modular Synthesis of Functionalized Butenolides by Oxidative Furan Fragmentation

2019 ◽  
Author(s):  
Jiajing Bao ◽  
Hailong Tian ◽  
Peicheng Yang ◽  
Jiachen Deng ◽  
Jinghan Gui
Keyword(s):  
Research Effort ◽  
Value Added ◽  
Building Blocks ◽  
Biologically Active ◽  
Coupling Reactions ◽  
Chemical Transformations ◽  
Modular Synthesis ◽  
Cross Coupling Reactions ◽  
Radical Trapping ◽  
Radical Fragmentation

The development of new chemical transformations to simplify the synthesis of valuable building blocks is a challenging task in organic chemistry and has been the focus of considerable research effort. From a synthetic perspective, it would be ideal if the natural reactivities of feedstock chemicals could be diverted to the production of high value-added compounds which are otherwise tedious to prepare. Here we report a chemical transformation that enables facile and modular synthesis of synthetically challenging yet biologically important functionalized butenolides from easily accessible furans. Specifically, Diels–Alder reactions between furans and singlet oxygen generate versatile hydroperoxide intermediates, which undergo iron(II)-mediated radical fragmentation in the presence of Cu(OAc)<sub>2</sub> or various radical trapping reagents to afford butenolides bearing a wide variety of appended remote functional groups, including olefins, halides, azides and aldehydes. The practical utility of this transformation is demonstrated by easy diversification of the products by means of cross-coupling reactions and, most importantly, by its ability to simplify the syntheses of known building blocks of eight biologically active natural products.

Expanded radialenes: Modular synthesis and properties of cross-conjugated enyne macrocycles

2008 ◽  
Vol 80 (3) ◽  
pp. 621-637 ◽  
Author(s):  
Rik R. Tykwinski ◽  
Mojtaba Gholami ◽  
Sara Eisler ◽  
Yuming Zhao ◽  
Frederic Melin ◽  
...  
Keyword(s):  
Cross Coupling ◽  
Building Blocks ◽  
Coupling Reactions ◽  
New Class ◽  
Modular Synthesis ◽  
The Past ◽  
Cross Coupling Reactions ◽  
Conjugated Macrocycles ◽  
Block Approach

During the past two decades, shape-persistent conjugated macrocycles with a broad spectrum of attributes and topologies have been synthesized. This includes macrocycles with remarkable electronic, optical, and supramolecular properties, as well as intriguing frameworks. Expanded radialenes are a class of conjugated shape-persistent macrocycles that arise from the formal insertion of acetylene units into a radialene framework. A related class of macrocycles, the expanded radiaannulenes, contains both endo- and exocyclic vinylene and vinylidene segments, respectively, and accordingly exhibits properties intermediate between radialenes and annulenes. Enyne building blocks have been developed that are suitable for forming a macrocyclic framework through a step-wise sequence of Pd-catalyzed cross-coupling reactions. This "building-block" approach allows us to explore a range of molecular architectures that will ultimately provide for an understanding of π-delocalization in these compounds. The synthesis and structural characterization of the first members of this new class of expanded radialenes and radiaannulenes are described.

Heterogeneous Metal Catalysis for the Environmentally Benign Synthesis of Medicinally Important Scaffolds, Intermediates, and Building Blocks

2021 ◽  
Vol 25 ◽  
Author(s):  
Maysa Ilamanova ◽  
Maxim Mastyugin ◽  
Christian Schäfer ◽  
Anne Kokel ◽  
Béla Török
Keyword(s):  
Building Blocks ◽  
Metal Catalysts ◽  
Solid Metal ◽  
Coupling Reactions ◽  
Hydrogenation Catalysts ◽  
Metal Catalysis ◽  
Solid Catalysts ◽  
Cross Coupling Reactions ◽  
Benign Synthesis ◽  
Two Sides

: This account provides a broad overview of the application of solid metal catalysts in synthetic chemistry with a focus on the synthesis of medicinally important scaffolds or building blocks. Heterogeneous catalysis is a fundamental contributor to green or sustainable synthesis. Despite this, many synthetic chemists overwhelmingly focus on homogeneous methods, and due to their unfamiliarity with solid catalysts, many would not consider using them. The primary purpose of this work is to bring solid catalysts and their application possibilities to the attention of synthetic chemists in a format that focuses on reactions, thus building a bridge between the two sides for the benefit of sustainable applications and, eventually, the whole society. The two major parts of this account describe the common types of solid metal catalysts and the applications of these catalysts in sustainable synthesis. The first part gives an overview of the major types of solid metal catalysts, including common hydrogenation catalysts to metal nanoparticles. The second and more extensive part illustrates the use of these catalysts in a thematic order based on reaction types, including hydrogenation, hydrogenolysis, oxidation, metathesis, cross-coupling reactions, and hydroformylation.

scholarly journals Tailored Catalysis for the F&F Industry

2021 ◽  
Vol 75 (7) ◽  
pp. 634-641
Author(s):  
Denis Jacoby
Keyword(s):  
Aldol Condensation ◽  
Cost Effective ◽  
Coupling Reactions ◽  
Chemical Transformations ◽  
Bond Forming ◽  
Heterogeneous Catalytic ◽  
Cross Coupling Reactions ◽  
Carbon Carbon Bond ◽  
The Difference ◽  
Insight Into

Over the past decades, scientists at Firmenich have focused their efforts on continuously improving chemical transformations for the production of F&F ingredients in order to make them safer, cleaner, more efficient and consequently cost effective, through the implementation of the Green Chemistry principles. Numerous examples of innovative catalytic technologies could be cited, particularly in the field of homogeneous and heterogeneous catalytic hydrogenation. Nevertheless, we chose here to provide a rare insight into the industrial application of some very useful and atom-economic carbon–carbon bond forming reactions. We selected two examples among others as a good illustration of how catalysis makes the difference compared to conventional stoichiometric approaches. The first example deals with catalysed cross-aldol condensation and the second example concerns catalysis of cross-coupling reactions.

scholarly journals Biocatalytic oxidative cross-coupling reactions for biaryl bond formation

2021 ◽  
Author(s):  
Lara Zetzsche ◽  
Jessica Yazarians ◽  
Suman Chakrabarty ◽  
Meagan Hinze ◽  
April Lukowski ◽  
...  
Keyword(s):  
Asymmetric Catalysis ◽  
Bond Formation ◽  
Cross Coupling ◽  
Building Blocks ◽  
Coupling Reactions ◽  
Cytochrome P450 Enzymes ◽  
Cross Coupling Reactions ◽  
Site Selectivity ◽  
Valuable Compounds ◽  
Selective Process

Despite their varied purposes, many indispensable molecules in medicine, materials, and asymmetric catalysis share a biaryl core. The necessity of joining arene building blocks to access these valuable compounds has inspired multiple approaches for biaryl bond formation and challenged chemists to develop increasingly concise and robust methods for this task. Oxidative coupling of two C–H bonds offers an efficient strategy for the formation of a biaryl C–C bond, however, fundamental challenges remain in controlling the reactivity and selectivity for uniting a given pair of substrates. Biocatalytic oxidative cross-coupling reactions have the potential to overcome limitations inherent to small molecule- mediated methods by providing a paradigm with catalyst-controlled selectivity. In this article, we disclose a strategy for biocatalytic cross-coupling through oxidative C–C bond formation using cytochrome P450 enzymes. We demonstrate the ability to catalyze cross-coupling reactions on a panel of phenolic substrates using natural P450 catalysts. Moreover, we engineer a P450 to possess the desired reactivity, site- selectivity, and atroposelectivity by transforming a low-yielding, unselective reaction into a highly efficient and selective process. This streamlined method for constructing sterically hindered biaryl bonds provides a programmable platform for assembling molecules with catalyst-controlled reactivity and selectivity.

scholarly journals Dual-functional cobalt catalyst enables electrocatalytic allylic C–H alkylation

2021 ◽  
Author(s):  
Ming Chen ◽  
Zheng-Jian Wu ◽  
Jinshuai Song ◽  
Hai-Chao Xu
Keyword(s):  
Value Added ◽  
Synthetic Methods ◽  
Radical Mechanism ◽  
Alkylation Reaction ◽  
Coupling Reactions ◽  
Carbon Nucleophiles ◽  
Noble Metal Catalysts ◽  
Cross Coupling Reactions ◽  
Dual Functional ◽  
Chemical Oxidants

Transition metal-catalyzed allylic substitution reactions of pre-activated allylation agents with nucleophiles are extensively studied synthetic methods that have enjoyed widespread applications in organic synthesis. The direct alkylation of allylic C–H bonds with nucleophiles, which minimizes pre-functionalization and converts inexpensive, abundantly available materials to value-added alkenyl-substituted products, remains challenging. Current methods generally involve C–H activation, require the use of noble-metal catalysts and stoichiometric chemical oxidants, and often show limited scope. Here we report an electrocatalytic allylic C–H alkylation reaction with carbon nucleophiles employing an easily available cobalt-salen complex as the molecular catalyst. These C(sp3)–H/C(sp3)–H cross-coupling reactions proceed through H2 evolution and require no external chemical oxidants. Importantly, the mild conditions and radical mechanism ensure excellent functional group tolerance and substrate compatibility with both linear and branched terminal alkenes. The synthetic utility of the electrochemical method is highlighted by its scalability (up to 200 mmol scale) and its successful application in the late-stage functionalization of complex structures.

Synthesis of Phenyl- and Pyridyl-substituted Benzyloxybenzaldehydes by Suzuki-Miyaura Coupling Reactions

2019 ◽  
Vol 16 (11) ◽  
pp. 1248-1257
Author(s):  
Hedvig Bölcskei ◽  
Andrea Német-Hanzelik ◽  
Zsófia Dubrovay ◽  
Viktor Háda ◽  
György Keglevich
Keyword(s):  
Sodium Ethoxide ◽  
Phenylboronic Acid ◽  
Biologically Active ◽  
Palladium Acetate ◽  
Coupling Reactions ◽  
Pharmaceutically Active Compounds ◽  
Active Compounds ◽  
Suzuki Method ◽  
Cross Coupling Reactions ◽  
Drug Substances

Background: Aryl-methoxybenzaldehydes substituted in various positions may serve as valuable starting materials for the synthesis of biologically active compounds. Methods: Biaryl-methoxybenzaldehydes and pyridyl-aryl-methoxybenzaldehydes were synthesized by the Suzuki-Miyaura cross-coupling reactions as intermediates of potential drug substances. Three different catalytic approaches were compared. The classical Suzuki method utilising tetrakis(triphenylphosphine)palladium and sodium ethoxide, the protocol applying palladium acetate and tri(o-tolyl)phosphine, and the method using tetrakis(triphenylphosphine)palladium and cesium carbonate, were studied. Results: The selected boronic acids were the classical phenylboronic acid, as well as 4-pyridineand 3-pyridineboronic acids. 26 New biaryl-methoxybenzaldehydes or pyridyl-phenylmethoxybenzaldehydes have been synthesized, which may be intermediates for pharmaceutically active compounds. Conclusion: The method of Anderson et al. was preferred, because it provides satisfactory results in all cases.

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