N-Phosphinoylimines: An Emerging Class of Reactive Intermediates for Stereoselective Organic Synthesis

Synthesis ◽  
2005 ◽  
pp. 1205-1227 ◽  
Author(s):  
Steven M. Weinreb ◽  
Robert K. Orr
Keyword(s):  
Organic Synthesis ◽  
Reactive Intermediates

7 Electrochemically Generated Nitrogen-Centered Radicals

2022 ◽  
Author(s):  
Z.-W. Hou ◽  
H.-C. Xu
Keyword(s):  
Hydrogen Atom ◽  
Organic Synthesis ◽  
Recent Progress ◽  
Reactive Intermediates ◽  
Hydrogen Atom Abstraction ◽  
Addition Reactions ◽  
Electrochemical Generation ◽  
Nitrogen Containing Compounds

Nitrogen-centered radicals are versatile reactive intermediates for organic synthesis. This chapter describes recent progress in the electrochemical generation and reactions of nitrogen-centered radicals. Under electrochemical conditions, various nitrogen-centered radicals are generated through electrolysis of readily available precursors such as N—H bonds or azides. These reactive intermediates undergo addition reactions to π-systems or hydrogen-atom abstraction to generate various nitrogen-containing compounds.

ChemInform Abstract: New Ways of Generating Organotin Reactive Intermediates for Organic Synthesis.

ChemInform ◽  
1989 ◽  
Vol 20 (27) ◽  
Author(s):  
W. P. NEUMANN ◽  
H. HILLGAERTNER ◽  
K. M. BAINES ◽  
R. DICKE ◽  
K. VORSPOHL ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Reactive Intermediates

Aziridinyl imines in organic synthesis: Development of tandem reaction strategies and application to total synthesis of natural products

2013 ◽  
Vol 85 (4) ◽  
pp. 741-753 ◽  
Author(s):  
Hee-Yoon Lee ◽  
Seog-Beom Song ◽  
Taek Kang ◽  
Yoon Jung Kim ◽  
Su Jeong Geum
Keyword(s):  
Natural Products ◽  
Total Synthesis ◽  
Organic Synthesis ◽  
Reactive Intermediates ◽  
Diazo Compounds ◽  
Tandem Reaction ◽  
Cycloaddition Reactions ◽  
Free Radical Reactions ◽  
Sulfur Ylide ◽  
Epoxide Formation

Aziridinyl imines are well-known carbene equivalents because they are precursors of diazo compounds from which reactive intermediates can be produced. These carbene equivalents can be utilized as zwitterionic species, diradicals, or 4π system for cycloaddition reactions. Thus, the intermediates derived from aziridinyl imines have been used in the sulfur-ylide-mediated epoxide formation, tandem free-radical reactions, or cyclopropanation reaction via carbene intermediates to form trimethylenemethane (TMM) diyls, which undergo [2 + 3] cycloaddition reactions to form cyclopentanoids. Diazo compounds generated from aziridinyl imines also react with allenes to form TMM diyls. This reaction was utilized in tandem cycloaddition reactions of linear substrates to form polyquinanes. These tandem reaction strategies were successfully applied to the total synthesis of various cyclopentanoid natural products.

Synthesis of Bench-Stable N-Quaternized Ketene N,O-Acetals and Preliminary Evaluation as Reagents in Organic Synthesis

2019 ◽  
Author(s):  
Alisha M. Blades ◽  
Danielle L. McConnell ◽  
Danielle Gomes Rodrigues ◽  
Phoebe V. Keyes ◽  
Justin C. Sonberg ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Lewis Acid ◽  
Reactive Intermediates ◽  
Electrophilic Aromatic Substitution ◽  
Preliminary Evaluation ◽  
Aromatic Substitution ◽  
Triflic Acid ◽  
Synthetic Intermediates ◽  
Nucleophilic Aromatic Substitutions

<div>N-Quaternized ketene N,O-acetals are typically an unstable, transient class of compounds most commonly observed as reactive intermediates. In this report, we describe a general approach to a variety of benchstable N-quaternized ketene N,O-acetals via treatment of pyridine or aniline bases with ethoxyacetylene and an appropriate Brønsted or Lewis acid (triflic acid, triflimide, or scandium(III) triflate). The resulting pyridinium and anilinium salts may be used as reagents or synthetic intermediates in multiple reaction types. For example, N-(1-ethoxyvinyl) pyridinium or anilinium salts can thermally release highly reactive O-ethyl ketenium ions that undergo electrophilic aromatic substitution with electron rich arenes. N-(1-ethoxyvinyl)-2-halopyridinium salts can also be utilized in peptide couplings as a derivative of Mukaiyama reagents, or react with alcohol and amines in nucleophilic aromatic substitutions.</div>

1.9 Oxygen-Centered Radicals

2021 ◽  
Author(s):  
J. Zhang ◽  
D. Liu ◽  
Y. Chen
Keyword(s):  
Hydrogen Atom ◽  
Visible Light ◽  
Organic Synthesis ◽  
Reactive Intermediates ◽  
Radical Addition ◽  
Hydrogen Atom Transfer ◽  
Reaction Conditions ◽  
Recent Advances ◽  
Carbon Carbon Bonds ◽  
Induced Reaction

AbstractOxygen-centered radicals (R1O•) are reactive intermediates in organic synthesis, with versatile synthetic utilities in processes such as hydrogen-atom transfer (HAT), β-fragmentation, radical addition to unsaturated carbon–carbon bonds, and rearrangement reactions. In this review, we focus on recent advances in the generation and transformation of oxygen-centered radicals, including (alkyl-, α-oxo-, aryl-) carboxyl, alkoxyl, aminoxyl, phenoxyl, and vinyloxyl radicals, and compare the reactivity of oxygen-centered radicals under traditional reaction conditions with their reactivity under visible-light-induced reaction conditions.

New reactions of γ-halocarbanions: underestimated reactive intermediates in organic synthesis

2004 ◽  
Vol 53 (9) ◽  
pp. 1846-1858 ◽  
Author(s):  
M. Barbasiewicz ◽  
M. Judka ◽  
M. Makosza
Keyword(s):  
Organic Synthesis ◽  
Reactive Intermediates

Interplay of synthesis and mechanism in asymmetric homogeneous catalysis

2001 ◽  
Vol 73 (2) ◽  
pp. 343-346 ◽  
Author(s):  
Nicholas J. Adams ◽  
Joachim Bargon ◽  
John M. Brown ◽  
Edward J. Farrington ◽  
Erwan Galardon ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Homogeneous Catalysis ◽  
Reaction Mechanisms ◽  
Palladium Catalysts ◽  
Reactive Intermediates ◽  
Intimate Relationship ◽  
Late Transition Metals ◽  
Ligand Structure ◽  
Late Transition ◽  
Asymmetric Homogeneous Catalysis

Asymmetric homogeneous catalysis forms one of the main planks of modern organic synthesis. It has developed rapidly and largely through the application of novel ligands, whose design is very much based on insight and intuition. At the same time, a better understanding of catalytic reaction mechanisms can contribute to further progress, since it can identify the intimate relationship between ligand structure and successful applications. The presentation will concentrate on the author's research with complexes of the late transition metals and include the search for superior methodologies in hydroboration, as well as ventures into the chemistry of reactive intermediates. The latter will be exemplified from work with rhodium and palladium catalysts.

1.5 Photochemistry and Radical Generation: Approaches in Mechanism Elucidation

2021 ◽  
Author(s):  
S. B. Cahoon ◽  
T. P. Yoon
Keyword(s):  
Case Studies ◽  
Organic Synthesis ◽  
Reactive Intermediates ◽  
Product Formation ◽  
Complex Reaction ◽  
Detailed Understanding ◽  
Physical Organic ◽  
Radical Generation ◽  
Complementary Techniques ◽  
Photocatalytic Reactions

AbstractThe development of photocatalytic reactions has reemerged as an active area of research in organic synthesis. A large variety of synthetically valuable transformations have now been developed that take advantage of the ease by which photocatalysts generate a variety of open-shelled reactive intermediates. The study of the mechanisms of these reactions, however, is a challenge, especially in increasingly sophisticated reactions that often involve multiple steps and complex reaction mixtures. Multiple complementary techniques often need to be utilized in tandem in order to develop a detailed understanding of these reactions. The first part of this review outlines many of the most common techniques that are used to interrogate the initiation and product-formation steps of a photocatalytic transformation. The second part describes case studies that provide contextual examples of how photophysical, electrochemical, physical organic, and computational investigations can be used together to provide insights into the mechanisms of complex photocatalytic reactions.

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