scholarly journals Sterically Controlled Late-Stage C–H Alkynylation of Arenes

2019 ◽  
Author(s):  
Arup Mondal ◽  
Hao Chen ◽  
Lea Flämig ◽  
Philipp Wedi ◽  
Manuel van Gemmeren
Keyword(s):  
Organic Chemistry ◽  
Late Stage ◽  
Functional Materials ◽  
Bioactive Molecules ◽  
Sonogashira Coupling ◽  
Traditional Methods ◽  
Complementary Product ◽  
Complementary Approach ◽  
Synthetic Intermediates ◽  
Directing Group

Phenylacetylenes are key structural motifs in organic chemistry, which find widespread applications in bioactive molecules, synthetic intermediates, functional materials and reagents. These molecules are typically prepared from pre-functionalized starting materials, e.g. using the Sonogashira coupling, or using directing group-based C–H activation strategies. While highly efficient, these approaches remain limited by their inherent selectivities for specific regioisomers. Herein we present a complementary approach based on an arene-limited nondirected C–H activation. The reaction is predominantly controlled by steric rather than electronic factors and thereby gives access to a complementary product spectrum with respect to traditional methods. A broad scope as well as the suitability of this protocol for late-stage functionalization are demonstrated.<br>

scholarly journals Sterically Controlled Late-Stage C–H Alkynylation of Arenes

2019 ◽  
Author(s):  
Arup Mondal ◽  
Hao Chen ◽  
Lea Flämig ◽  
Philipp Wedi ◽  
Manuel van Gemmeren
Keyword(s):  
Organic Chemistry ◽  
Late Stage ◽  
Functional Materials ◽  
Bioactive Molecules ◽  
Sonogashira Coupling ◽  
Traditional Methods ◽  
Complementary Product ◽  
Complementary Approach ◽  
Synthetic Intermediates ◽  
Directing Group

Phenylacetylenes are key structural motifs in organic chemistry, which find widespread applications in bioactive molecules, synthetic intermediates, functional materials and reagents. These molecules are typically prepared from pre-functionalized starting materials, e.g. using the Sonogashira coupling, or using directing group-based C–H activation strategies. While highly efficient, these approaches remain limited by their inherent selectivities for specific regioisomers. Herein we present a complementary approach based on an arene-limited nondirected C–H activation. The reaction is predominantly controlled by steric rather than electronic factors and thereby gives access to a complementary product spectrum with respect to traditional methods. A broad scope as well as the suitability of this protocol for late-stage functionalization are demonstrated.<br>

Reductive Cleavage of Secondary Sulfonamides: Converting Terminal Functional Groups into Versatile Synthetic Handles

2019 ◽  
Author(s):  
Patrick Fier ◽  
Suhong Kim ◽  
Kevin M. Maloney
Keyword(s):  
Functional Groups ◽  
Late Stage ◽  
Reductive Cleavage ◽  
Bioactive Molecules ◽  
General Method

Sulfonamides are pervasive in drugs and agrochemicals, yet are typically considered as terminal functional groups rather than synthetic handles. To enable the general late-stage functionalization of secondary sulfonamides, we have developed a mild and general method to reductively cleave the N-S bonds of sulfonamides to generate sulfinates and amines, components which can further react <i>in-situ</i> to access a variety of other medicinally relevant functional groups. The utility of this platform is highlighted by the selective manipulation of several complex bioactive molecules.

Unique Functional Materials Derived from β-Amino Acid Oligomers

2017 ◽  
Vol 70 (2) ◽  
pp. 126 ◽  
Author(s):  
Mark P. Del Borgo ◽  
Ketav Kulkarni ◽  
Marie-Isabel Aguilar
Keyword(s):  
Amino Acid ◽  
Drug Design ◽  
Self Assembly ◽  
Functional Materials ◽  
Bioactive Molecules ◽  
Peptide Drug ◽  
New Materials ◽  
Amino Acid Oligomers

The unique structures formed by β-amino acid oligomers, or β-peptide foldamers, have been studied for almost two decades, which has led to the discovery of several distinctive structures and bioactive molecules. Recently, this area of research has expanded from conventional peptide drug design to the formation of assemblies and nanomaterials by peptide self-assembly. The unique structures formed by β-peptides give rise to a set of new materials with altered properties that differ from conventional peptide-based materials; such new materials may be useful in several bio- and nanomaterial applications.

scholarly journals Kinetic resolution of indolines by asymmetric hydroxylamine formation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gang Wang ◽  
Ran Lu ◽  
Chuangchuang He ◽  
Lei Liu
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Synthesis ◽  
Late Stage ◽  
Kinetic Resolution ◽  
High Efficiency ◽  
Bond Formation ◽  
Bioactive Molecules ◽  
Environmentally Benign ◽  
Secondary Amines

AbstractCatalytic kinetic resolution of amines represents a longstanding challenge in chemical synthesis. Here, we described a kinetic resolution of secondary amines through oxygenation to produce enantiopure hydroxylamines involving N–O bond formation. The economic and practical titanium-catalyzed asymmetric oxygenation with environmentally benign hydrogen peroxide as oxidant is applicable to a range of racemic indolines with multiple stereocenters and diverse substituent patterns in high efficiency with efficient chemoselectivity and enantio-discrimination. Late-stage asymmetric oxygenation of bioactive molecules that are otherwise difficult to synthesize was also explored.

Biocatalytic approaches for enantio and diastereoselective synthesis of chiral β-nitroalcohols

2021 ◽  
Author(s):  
D. H. Sreenivasa Rao ◽  
Ayon Chatterjee ◽  
Santosh Kumar Padhi
Keyword(s):  
Bioactive Molecules ◽  
Diastereoselective Synthesis ◽  
Synthetic Intermediates

Chiral β-nitroalcohols are versatile synthetic intermediates for several pharmaceuticals, and bioactive molecules. This review describes the importance and various biocatalytic approaches for their enantio and diastereoselective synthesis.

Selective C–H Bond Fluorination of Phenols with a Removable Directing Group: Late-Stage Fluorination of 2-Phenoxyl Nicotinate Derivatives

ACS Catalysis ◽  
2015 ◽  
Vol 5 (5) ◽  
pp. 2846-2849 ◽  
Author(s):  
Shao-Jie Lou ◽  
Qi Chen ◽  
Yi-Feng Wang ◽  
Dan-Qian Xu ◽  
Xiao-Hua Du ◽  
...  
Keyword(s):  
Late Stage ◽  
Directing Group

scholarly journals Liquid-phase exfoliated graphene: functionalization, characterization, and applications

2014 ◽  
Vol 5 ◽  
pp. 2328-2338 ◽  
Author(s):  
Mildred Quintana ◽  
Jesús Iván Tapia ◽  
Maurizio Prato
Keyword(s):  
Organic Chemistry ◽  
Liquid Phase ◽  
Chemical Reactions ◽  
Functional Materials ◽  
Atomic Plane ◽  
Graphene Sheets ◽  
Exfoliated Graphene ◽  
Graphene Functionalization ◽  
Chemical Strategies ◽  
Insight Into

The development of chemical strategies to render graphene viable for incorporation into devices is a great challenge. A promising approach is the production of stable graphene dispersions from the exfoliation of graphite in water and organic solvents. The challenges involve the production of a large quantity of graphene sheets with tailored distribution in thickness, size, and shape. In this review, we present some of the recent efforts towards the controlled production of graphene in dispersions. We also describe some of the chemical protocols that have provided insight into the vast organic chemistry of the single atomic plane of graphite. Controlled chemical reactions applied to graphene are expected to significantly improve the design of hierarchical, functional platforms, driving the inclusion of graphene into advanced functional materials forward.

scholarly journals Late-Stage β-C(sp3)–H Deuteration of Carboxylic Acids

2021 ◽  
Author(s):  
Alexander Uttry ◽  
Sourjya Mal ◽  
Manuel van Gemmeren
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Late Stage ◽  
Bioactive Molecules ◽  
Wide Range ◽  
Catalyst Systems ◽  
First Time

Carboxylic acid moieties are highly abundant in bioactive molecules. In this study we describe the late-stage β-C(sp<sup>3</sup>)–H deuteration of free carboxylic acids. Based on our finding that the C–H activation with our catalyst systems is reversible, the de-deuteration process was first optimized. The resulting conditions involve ethylenediamine-based ligands, which, amongst other positions, for the first time enables the functionalization of non-activated methylene β-C(sp<sup>3</sup>)–H bonds and can be used to achieve the desired deuteration when using a deuterated solvent. The reported method allows for the functionalization of a wide range of free carboxylic acids with diverse substitution patterns, as well as the late-stage deuteration of bioactive molecules and related frameworks.

scholarly journals Merging Shuttle Reactions and Paired Electrolysis: E-Shuttle Unlocks Reversible Halogenations

2020 ◽  
Author(s):  
Xichang Dong ◽  
Johannes L. Röckl ◽  
Siegfried R. Waldvogel ◽  
Bill Morandi
Keyword(s):  
Organic Chemistry ◽  
Flame Retardants ◽  
Environmental Pollutant ◽  
Halogen Bonds ◽  
Recycling Process ◽  
New Horizons ◽  
Synthetic Intermediates ◽  
Halogenated Pollutants ◽  
Hazardous Compounds ◽  
Different Soils

<p>Polyhalogenated molecules have found widespread applications as flame retardants, pest-control agents, polymers and pharmaceuticals. They also serve as versatile synthetic intermediates in organic chemistry due to the inherent reactivity of carbon-halogen bonds. Despite these attractive features, the preparation of polyhalogenated molecules still mainly relies on the use of highly toxic and corrosive halogenating reagents, such as Cl<sub>2</sub> and Br<sub>2</sub>, which are hazardous compounds to transport, store, and handle. Moreover, the use of such highly reactive reagents inherently makes the development of the reverse reactions, <i>retro</i>-dihalogenations, highly challenging, despite their potential for the recycling of persistent halogenated pollutants. Here, we introduce an electrochemically-assisted shuttle<i> (e-shuttle)</i> paradigm for the facile and scalable interconversion of alkenes and vicinal dihalides, a class of reactions which can be used both to synthesize useful polyhalogenated molecules from simple alkenes and to recycle waste material through <i>retro</i>-dihalogenation. The power of this reaction is best highlighted by an example, in which different soils contaminated with a persistent environmental pollutant (Lindane), could be directly used as Cl<sub>2</sub>-donors for the transfer dichlorination of simple feedstock alkenes, merging a recycling process with a synthetically relevant dichlorination reaction. We further demonstrate that this paired electrolysis-enabled shuttle protocol, which uses a simple setup and inexpensive electrodes, is applicable to four different, synthetically useful transfer halogenation reactions, and can be readily scaled-up to a decagram scale. In a broader context, the symbiotic merging of shuttle reactions and electrochemistry introduced in this work opens new horizons for safer transfer functionalization reactions that will address important challenges across the molecular sciences.</p> <div><br><div> </div> </div>

scholarly journals Site-Selective Alkoxylation of Benzylic C–H Bonds via Photoredox Catalysis

2019 ◽  
Author(s):  
Byung Joo Lee ◽  
kimberly deglopper ◽  
Tehshik Yoon
Keyword(s):  
Late Stage ◽  
Functional Group ◽  
Bond Formation ◽  
Bioactive Molecules ◽  
Site Selectivity ◽  
Wide Range ◽  
High Site ◽  
Alkoxy Groups ◽  
Site Selective ◽  
Mediated Oxidation

<div> <div> <div> <p>There are relatively few methods that accom- plish the selective alkoxylation of sp3-hybridized C–H bonds, particularly in comparison to the numerous analogous strate- gies for C–N and C–C bond formation. We report a photo- catalytic protocol for the functionalization of benzylic C–H bonds with a wide range of readily available oxygen nucleo- philes. Our strategy merges the photoredox activation of arenes with copper(II)-mediated oxidation of the resulting benzylic radicals, which enables the introduction of benzylic C–O bonds with high site selectivity, chemoselectivity, and functional group tolerance. This method enables the late- stage introduction of complex alkoxy groups into bioactive molecules, providing a practical new tool with potential appli- cations in synthesis and medicinal chemistry. </p> </div> </div> </div>

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