scholarly journals Polymeric Near Infrared Emitters with Bay-Annulated Indigo Moieties

2021 ◽  
Author(s):  
Ana Clara Beltran Rodrigues ◽  
Anika Eckert ◽  
João Manuel Pina ◽  
Ullrich Scherf ◽  
Joao Sergio Seixas de Melo
Keyword(s):  
Near Infrared ◽  
Cross Coupling ◽  
Building Blocks ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Infrared Emitters

Three new copolymers based on bay-annulated indigo (BAI) building blocks were synthesized through Stille-type cross-coupling reactions, alternating the electron-deficient BAI units with thiophene-based donor moieties. Those polymers showed absorption and...

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.

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 Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

2019 ◽  
Vol 15 ◽  
pp. 1416-1424
Author(s):  
Ruben Pomar Fuentespina ◽  
José Angel Garcia de la Cruz ◽  
Gabriel Durin ◽  
Victor Mamane ◽  
Jean-Marc Weibel ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Cross Coupling ◽  
Functional Materials ◽  
Building Blocks ◽  
Cascade Process ◽  
Coupling Reactions ◽  
One Pot ◽  
Bioactive Natural Products ◽  
Cross Coupling Reactions ◽  
Synthetic Approaches

1,3-Enynes are important building blocks in organic synthesis and also constitute the key motif in various bioactive natural products and functional materials. However, synthetic approaches to stereodefined substituted 1,3-enynes remain a challenge, as they are limited to Wittig and cross-coupling reactions. Herein, stereodefined 1,3-enynes, including tetrasubstituted ones, were straightforwardly synthesized from cis or trans-alkynylated oxiranes in good to excellent yields by a one-pot cascade process. The procedure relies on oxirane deprotonation, borylation and a stereospecific rearrangement of the so-formed alkynyloxiranyl borates. This stereospecific process overall transfers the cis or trans-stereochemistry of the starting alkynyloxiranes to the resulting 1,3-enynes.

scholarly journals Fluorinated Organic Paramagnetic Building Blocks for Cross-Coupling Reactions

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5427
Author(s):  
Larisa V. Politanskaya ◽  
Pavel A. Fedyushin ◽  
Tatyana V. Rybalova ◽  
Artem S. Bogomyakov ◽  
Nargiz B. Asanbaeva ◽  
...  
Keyword(s):  
Cross Coupling ◽  
Exchange Interactions ◽  
Halogen Bonding ◽  
Building Blocks ◽  
Coupling Reactions ◽  
Tert Butyl ◽  
Whole Process ◽  
Cross Coupling Reactions ◽  
Intramolecular Exchange ◽  
Tert Butylamine

New stable polyfluorinated nitroxide radicals for use in cross-coupling reactions, namely, N-tert-butyl-N-oxyamino-2,3,5,6-tetrafluoro-4-iodobenzene and N-tert-butyl-N-oxyamino-2,3,5,6-tetrafluoro-4-ethynylbenzene, were prepared from perfluoroiodobenzene. The reaction of the polyfluoro derivative with tert-butylamine under autoclaving conditions leading to the formation of N-tert-butyl-2,3,5,6-tetrafluoro-4-iodoaniline proved to be the key stage of the whole process. The fluorinated tert-butyl iodophenyl nitroxide was found to form in a solid state via N–O···I halogen bonds, a one-dimensional assembly of the radicals. The acceptor role of the nitroxide group in the halogen bonding changes to a donor role when the nitroxide reacts with Cu(hfac)2. In the last case, zero-dimensional assembly prevails, giving a three-spin complex with axial coordinated nitroxide groups and, as a consequence, causing ferromagnetic intramolecular exchange interactions between Cu(II) and radical spins.

Recent Advances in the Synthesis of Diverse Libraries of Small-Molecule Building Blocks in Ionic Liquids (ILs)

Synlett ◽  
2021 ◽  
Author(s):  
Kenneth K. Laali ◽  
Rajesh G. Kalkhambkar ◽  
Suraj M. Sutar
Keyword(s):  
Ionic Liquids ◽  
Small Molecule ◽  
Biginelli Reaction ◽  
Cross Coupling ◽  
Building Blocks ◽  
Solvent Mixtures ◽  
Coupling Reactions ◽  
Ion Chemistry ◽  
Cross Coupling Reactions ◽  
Recent Advances

AbstractThe Account describes recent advances, from the authors’ laboratories, in the synthesis of diverse libraries of small-molecule building blocks employing ionic liquids (ILs). The ability of ILs to act as catalysts/promoters/solvents for electrophilic and onium ion chemistry, as well as in metal-mediated cross-coupling reactions, and the potential to sequence/hyphenate these methods, have opened up new opportunities for facile assembly of functional small molecules with increased complexity from readily available precursors. While Brønsted acidic IL/IL solvent mixtures are suitable media for carbocation and onium ion chemistry, piperidine-appended IL/IL solvent mixtures can successfully catalyze a variety of base-catalyzed reactions. Several widely practiced transformations including ‘name reactions’ were adapted and performed efficiently in ILs.1 Introduction2 Aryldiazonium Salts and Aryltriazenes as Coupling Partners in Metal-Mediated C–C Cross-Coupling Reactions in ILs3 Expanding the Scope of Metal-Mediated Cross-Coupling Reactions in ILs4 Application of ILs in Synthesis and Functionalization of Hetero­cycles5 Expanding the Scope of Amide Synthesis in ILs6 Generation and Chemistry of ‘Tamed’ Propargylic Cations in ILs7 Newer Nitration Methods for Arenes and Heteroarenes in ILs8 Halofunctionalization in ILs9 ‘Name Reactions’and Other Widely Practiced Synthetic Transformations in ILs9.1 The Biginelli Reaction9.2 Nitrile Synthesis by the Schmidt Reaction9.3 Rupe Rearrangement9.4 Synthesis of 1,3-Dioxanes via Prins Reaction in [BMIM(SO3H)][OTf]9.5 Synthesis of Cyclopropanes and Oxiranes by the Corey–Chaykovsky (CC) Reaction10 Conclusions and Closing Remarks

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