Recent advances in Minisci-type reactions and applications in organic synthesis

2020 ◽  
Vol 24 ◽  
Author(s):  
Wengui Wang ◽  
Shoufeng Wang
Keyword(s):  
Free Radical ◽  
Hydrogen Atom ◽  
Organic Synthesis ◽  
Radical Reactivity ◽  
Atom Loss ◽  
Radical Generation ◽  
In Situ Generation ◽  
Thermal Cleavage ◽  
Synthetic Chemist

Abstract:: Minisci-type reactions have become widely known as reactions that involve the addition of carbon-centered radicals to basic heteroarenes followed by formal hydrogen atom loss. While the originally developed protocols for radical generation remain in active use today, in recent years by a new array of radical generation strategies allow use of a wider variety of radical precursors that often operate under milder and more benign conditions. New transformations based on free radical reactivity are now available to a synthetic chemist looking to utilize a Minisci-type reaction. Radical-generation methods based on photoredox catalysis and electrochemistry, which utilize thermal cleavage or the in situ generation of reactive radical precursors, have become popular approaches. Our review will cover the remarkably literature that has appeared on this topic in recent 5 years, from 2015-01 to 2020-01, in an attempt to provide guidance to the synthetic chemist, on both the challenges that have been overcome and applications in organic synthesis.

scholarly journals A cross-dehydrogenative C(sp3)−H heteroarylation via photo-induced catalytic chlorine radical generation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chia-Yu Huang ◽  
Jianbin Li ◽  
Chao-Jun Li
Keyword(s):  
Hydrogen Atom ◽  
Hydrogen Evolution ◽  
Alkyl Radical ◽  
Cobalt Catalyst ◽  
Alkylation Reaction ◽  
Hydrogen Atom Abstraction ◽  
Dehydrogenative Coupling ◽  
Radical Generation ◽  
Limited Scope

AbstractHydrogen atom abstraction (HAT) from C(sp3)–H bonds of naturally abundant alkanes for alkyl radical generation represents a promising yet underexplored strategy in the alkylation reaction designs since involving stoichiometric oxidants, excessive alkane loading, and limited scope are common drawbacks. Here we report a photo-induced and chemical oxidant-free cross-dehydrogenative coupling (CDC) between alkanes and heteroarenes using catalytic chloride and cobalt catalyst. Couplings of strong C(sp3)–H bond-containing substrates and complex heteroarenes, have been achieved with satisfactory yields. This dual catalytic platform features the in situ engendered chlorine radical for alkyl radical generation and exploits the cobaloxime catalyst to enable the hydrogen evolution for catalytic turnover. The practical value of this protocol was demonstrated by the gram-scale synthesis of alkylated heteroarene with merely 3 equiv. alkane loading.

scholarly journals Recent Advances in the Synthesis of Isothiocyanates Using Elemental Sulfur

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1081
Author(s):  
András Gy. Németh ◽  
Péter Ábrányi-Balogh
Keyword(s):  
Natural Products ◽  
Best Practices ◽  
Organic Synthesis ◽  
Elemental Sulfur ◽  
Biologically Active ◽  
Primary Amines ◽  
Pharmaceutical Ingredients ◽  
Recent Developments ◽  
In Situ Generation

Isothiocyanates (ITCs) are biologically active molecules found in several natural products and pharmaceutical ingredients. Moreover, due to their high and versatile reactivity, they are widely used as intermediates in organic synthesis. This review considers the best practices for the synthesis of ITCs using elemental sulfur, highlighting recent developments. First, we summarize the in situ generation of thiocarbonyl surrogates followed by their transformation in the presence of primary amines leading to ITCs. Second, carbenes and amines afford isocyanides, and the further reaction of this species with sulfur readily generates ITCs under thermal, catalytic or basic conditions. Additionally, we also reveal that in the catalyst-free reaction of isocyanides and sulfur, two—until this time overlooked and not investigated—different mechanistic pathways exist.

1.13 Intramolecular Hydrogen-Atom Transfer

2021 ◽  
Author(s):  
S. Treacy ◽  
X. Zhang ◽  
T. Rovis
Keyword(s):  
Hydrogen Atom ◽  
Functional Groups ◽  
Open Shell ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Stable Carbon ◽  
Radical Reactivity ◽  
Recent Advances ◽  
Synthetic Chemist ◽  
Intramolecular Hydrogen

AbstractRecent advances in intramolecular hydrogen-atom transfer (HAT) have demonstrated significant utility in C—H functionalization through highly reactive open-shell intermediates. The intramolecular transposition of radical reactivity from select functional groups to generate more stable carbon-centered radicals often proceeds with high regioselectivity, providing novel bond disconnections at otherwise inert and largely indistinguishable positions. This chapter explores the functional groups capable of intramolecular HAT to generate remote radicals and the transformations currently available to the synthetic chemist.

scholarly journals Unexpected in-situ Free Radical Generation and Catalysis to Ag/Polymer Nanocomposite

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Yifan Pang ◽  
Ruixue Wei ◽  
Jintao Wang ◽  
Liuhe Wei ◽  
Chunhui Li
Keyword(s):  
Free Radical ◽  
Polymer Nanocomposite ◽  
Free Radical Generation ◽  
Radical Generation

scholarly journals Nucleophilic Trifluoromethylation Reactions Involving Copper(I) Species: From Organometallic Insights to Scope

Synthesis ◽  
2019 ◽  
Vol 51 (14) ◽  
pp. 2809-2820 ◽  
Author(s):  
Ángel L. Mudarra ◽  
Sara Martínez de Salinas ◽  
Mónica H. Pérez-Temprano
Keyword(s):  
Organic Synthesis ◽  
Historical Perspective ◽  
Short Review ◽  
Copper Species ◽  
Bond Forming ◽  
Comprehensive Picture ◽  
Real Behavior ◽  
In Situ Generation ◽  
Reaction Media

Over the last decades, trifluoromethyl copper(I) complexes have played a key role as reactive species in C–CF3 bond-forming reactions. This Short Review not only covers selected examples of relevant copper-mediated or catalyzed nucleophilic trifluoromethylation reactions, which is one of the most active fields in organic synthesis, but also provides a comprehensive picture of the real behavior of these copper species, including ubiquitous cuprates, in the reaction media.1 Introduction2 Historical Perspective of the Identification of Relevant Trifluoro- methyl Copper(I) Species3 In Situ Generation of Active Trifluoromethyl Copper(I) Species 4 Well-Defined Active Trifluoromethyl Copper(I) Complexes5 Recent Advances on the Performance of Trifluoromethylation Protocols6 Conclusions

Kinetics of the Interaction of Atomic Species With (100) Gallium Arsenide Surfaces

1999 ◽  
Vol 573 ◽  
Author(s):  
Ligia Gheorghita ◽  
Elmer Ogryzlo
Keyword(s):  
Hydrogen Atom ◽  
Room Temperature ◽  
Microwave Plasma ◽  
Subsequent Treatment ◽  
Photoluminescence Intensity ◽  
Carrier Recombination ◽  
Hydrogen Deuterium ◽  
Atom Loss ◽  
Kinetics Of

ABSTRACTThe interactions of atomic hydrogen, deuterium and sulfur with (100) GaAs surfaces have been studied. The atoms were produced in a remote microwave plasma and their effect on carrier recombination velocities was continuously monitored in situ by the change in photoluminescence intensity (PLI). It was observed that the PLI increased by about 1–2 orders of magnitude following a few seconds exposure to hydrogen and deuterium atoms. A subsequent treatment with sulfur atoms further increased the PLI. A kinetic analysis of the room temperature hydrogen atom interactions with the (100) GaAs surface was attempted. A similar behavior was observed at higher temperatures when hydrogen and deuterium atoms were allowed to interact with a SiSiO2 interface. A comparison of the two systems leads us to conclude that the hydrogen and deuterium atoms can be trapped at interstitial sites near these interfaces. The kinetics of the hydrogen atom loss from these semiconductors is presented and analyzed in terms of a distribution of trapping sites.

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