scholarly journals CO2-Mediated Pd-Catalyzed Stereo- and Regioselective Arylation of Free Allylamines

2020 ◽  
Author(s):  
Vinod Landge ◽  
Justin Maxwell ◽  
Pratibha Chand-Thakuri ◽  
Mohit Kapoor ◽  
Evan Diemler ◽  
...  
Keyword(s):  
Catalyst Design ◽  
Powerful Method ◽  
Mechanistic Studies ◽  
Atom Economy ◽  
Biologically Relevant ◽  
Mild Conditions ◽  
Selective Functionalization ◽  
Michael Acceptors ◽  
Key Features ◽  
Terminal Olefins

Mizoroki-Heck couplings are a powerful method for elaborating alkene feedstocks. While selective functionalization of terminal olefins has been achieved by catalyst design, selective functionalization of internal olefins has generally required use of directing groups except in the case of Michael acceptors. Allylamine substrates have typically required protection to be suitable for these reactions, decreasing the step and atom economy of these procedures. Herein we demonstrate that the addition of CO<sub>2</sub> (dry ice) allows for the reproducible stereospecific arylation of both secondary and primary allylamines in the presence of a Pd<sup>II</sup> catalyst. Notably, the product 3,3’-diarylallylamine motif is prevalent in a variety of biologically-relevant structures, and this method represents the most straightforward synthesis of these targets to date. Key features of the method are the ability to access relatively mild conditions that facilitate a broad substrate scope, as well as direct diarylation of terminal allylamine substrates. In addition, several complex and therapeutically-relevant molecules are included to demonstrate the utility of the transformation. Mechanistic studies point to an amine-directed reaction where CO<sub>2</sub> serves to protect the substrate and product from degradation.

scholarly journals CO2-Mediated Pd-Catalyzed Stereo- and Regioselective Arylation of Free Allylamines

2020 ◽  
Author(s):  
Vinod Landge ◽  
Justin Maxwell ◽  
Pratibha Chand-Thakuri ◽  
Mohit Kapoor ◽  
Evan Diemler ◽  
...  
Keyword(s):  
Catalyst Design ◽  
Powerful Method ◽  
Mechanistic Studies ◽  
Atom Economy ◽  
Biologically Relevant ◽  
Mild Conditions ◽  
Selective Functionalization ◽  
Michael Acceptors ◽  
Key Features ◽  
Terminal Olefins

Mizoroki-Heck couplings are a powerful method for elaborating alkene feedstocks. While selective functionalization of terminal olefins has been achieved by catalyst design, selective functionalization of internal olefins has generally required use of directing groups except in the case of Michael acceptors. Allylamine substrates have typically required protection to be suitable for these reactions, decreasing the step and atom economy of these procedures. Herein we demonstrate that the addition of CO2 (dry ice) allows for the reproducible stereospecific arylation of both secondary and primary allylamines in the presence of a PdII catalyst. Notably, the product 3,3’-diarylallylamine motif is prevalent in a variety of biologically-relevant structures, and this method represents the most straightforward synthesis of these targets to date. Key features of the method are the ability to access relatively mild conditions that facilitate a broad substrate scope, as well as direct diarylation of terminal allylamine substrates. In addition, several complex and therapeutically-relevant molecules are included to demonstrate the utility of the transformation. Mechanistic studies point to an amine-directed reaction where CO2 serves to protect the substrate and product from degradation.

scholarly journals CO2 As A Transient Directing Group for the Oxidative Heck Coupling of Free Allylamines With Aryl Iodides

2020 ◽  
Author(s):  
Vinod Landge ◽  
Justin Maxwell ◽  
Pratibha Chand-Thakuri ◽  
Mohit Kapoor ◽  
Evan Diemler ◽  
...  
Keyword(s):  
Catalyst Design ◽  
Heck Coupling ◽  
Powerful Method ◽  
Atom Economy ◽  
Biologically Relevant ◽  
Mild Conditions ◽  
Selective Functionalization ◽  
Michael Acceptors ◽  
Directing Group ◽  
Terminal Olefins

Oxidative Heck couplings are a powerful method for elaborating alkene feedstocks. While selective functionalization of terminal olefins has been achieved by catalyst design, selective functionalization of internal olefins has generally required use of directing groups except in the case of Michael acceptors. Allylamine substrates have typically required protection to be suitable for these reactions, decreasing the step and atom economy of these procedures. Herein we demonstrate that the addition of CO<sub>2</sub> (dry ice) as a transient directing group allows for the stereospecific arylation of both secondary and primary allylamines in the presence of a Pd<sup>II</sup> catalyst. Notably, the product 3,3’-diarylallylamine motif is prevalent in a variety of biologically-relevant structures, and this method represents the most straightforward synthesis of these targets to date. Key features of the method are the ability to access relatively mild conditions that facilitate a broad substrate scope, as well as direct diarylation of terminal allylamine substrates. In addition, several complex and therapeutically-relevant molecules are included to demonstrate the utility of the transformation.

γ-C(sp2)–H Arylation of Allylamines Using PdII and CO2 as a Transient Directing Group

2020 ◽  
Author(s):  
Vinod Landge ◽  
Justin Maxwell ◽  
Pratibha Chand-Thakuri ◽  
Mohit Kapoor ◽  
Evan Diemler ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Transition Metal ◽  
Complex Molecules ◽  
Dry Ice ◽  
Biologically Relevant ◽  
Mild Conditions ◽  
Directing Group ◽  
Key Features ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

Although C–H activation has become a powerful tool in the synthesis of complex molecules from simple precursors, transition metal-catalyzed reactions involving free alkenes often lead to insertion-type reactions. Herein we demonstrate that the addition of carbon dioxide in the form of dry ice allows the C(<i>sp</i><sup>2</sup>)–H arylation of both secondary and primary allylamines in the presence of a Pd<sup>II</sup> catalyst. Notably, the product 3,3’-diarylallylamine motif is prevalent in a variety of biologically-relevant structures, and this method represents the most straightforward synthesis of these targets to date. Key features of the method are the ability to access relatively mild conditions that facilitate a broad substrate scope, as well as direct diarylation of terminal allylamine substrates. In addition, several complex and therapeutically-relevant molecules are included to demonstrate the utility of the transformation.

scholarly journals Photocatalytic three-component asymmetric sulfonylation via direct C(sp3)-H functionalization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shi Cao ◽  
Wei Hong ◽  
Ziqi Ye ◽  
Lei Gong
Keyword(s):  
Asymmetric Catalysis ◽  
Organic Synthesis ◽  
Photochemical Reaction ◽  
Low Cost ◽  
Bioactive Molecules ◽  
Atom Economy ◽  
Mild Conditions ◽  
Wide Range ◽  
Unsaturated Carbonyl Compound ◽  
Direct Functionalization

AbstractThe direct and selective C(sp3)-H functionalization of cycloalkanes and alkanes is a highly useful process in organic synthesis owing to the low-cost starting materials, the high step and atom economy. Its application to asymmetric catalysis, however, has been scarcely explored. Herein, we disclose our effort toward this goal by incorporation of dual asymmetric photocatalysis by a chiral nickel catalyst and a commercially available organophotocatalyst with a radical relay strategy through sulfur dioxide insertion. Such design leads to the development of three-component asymmetric sulfonylation involving direct functionalization of cycloalkanes, alkanes, toluene derivatives or ethers. The photochemical reaction of a C(sp3)-H precursor, a SO2 surrogate and a common α,β-unsaturated carbonyl compound proceeds smoothly under mild conditions, delivering a wide range of biologically interesting α-C chiral sulfones with high regio- and enantioselectivity (>50 examples, up to >50:1 rr and 95% ee). This method is applicable to late-stage functionalization of bioactive molecules, and provides an appealing access to enantioenriched compounds starting from the abundant hydrocarbon compounds.

scholarly journals Recent Advances in Rapid Synthesis of Non-proteinogenic Amino Acids from Proteinogenic Amino Acids Derivatives via Direct Photo-Mediated C–H Functionalization

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5270
Author(s):  
Zhenbo Yuan ◽  
Xuanzhong Liu ◽  
Changmei Liu ◽  
Yan Zhang ◽  
Yijian Rao
Keyword(s):  
Amino Acids ◽  
Direct Synthesis ◽  
Environmentally Friendly ◽  
Powerful Method ◽  
Rapid Synthesis ◽  
Conservation Of Energy ◽  
Mild Conditions ◽  
Recent Advances ◽  
Recent Developments

Non-proteinogenic amino acids have attracted tremendous interest for their essential applications in the realm of biology and chemistry. Recently, rising C–H functionalization has been considered an alternative powerful method for the direct synthesis of non-proteinogenic amino acids. Meanwhile, photochemistry has become popular for its predominant advantages of mild conditions and conservation of energy. Therefore, C–H functionalization and photochemistry have been merged to synthesize diverse non-proteinogenic amino acids in a mild and environmentally friendly way. In this review, the recent developments in the photo-mediated C–H functionalization of proteinogenic amino acids derivatives for the rapid synthesis of versatile non-proteinogenic amino acids are presented. Moreover, postulated mechanisms are also described wherever needed.

scholarly journals Zn(L-proline)2: An efficient and reusable organocatalyst for the synthesis of polyfunctionally substituted pyrans and 2-amino-4-aryl-8-oxo-4,8-dihydropyrano[3,2-b]pyran derivatives

2019 ◽  
Vol 10 (2) ◽  
pp. 166-170 ◽  
Author(s):  
Fatma Ahmed Abo Elsoud ◽  
Mohamed Abd-Elmonem ◽  
Mohamed Abo Elsebaa ◽  
Kamal Usef Sadek
Keyword(s):  
Kojic Acid ◽  
Aromatic Aldehydes ◽  
Efficient Synthesis ◽  
Atom Economy ◽  
Short Reaction Time ◽  
Biologically Relevant ◽  
Three Component Reaction ◽  
High Yields ◽  
Organometallic Catalyst ◽  
Work Up

Efficient synthesis of non-annulated 2-amino-4H-pyrans and 2-amino-8-oxo-4,8-dihydropyrano[3,2-b]pyran derivatives, which are biologically relevant heterocycles is achieved, utilizing a domino three-component reaction of ethyl acetoacetate or kojic acid with aromatic aldehydes and malononitrile catalyzed by Zn(L-proline)2 as reusable organometallic catalyst. The process exhibits high atom economy, short reaction time, simple work up, high yields and environmentally friendly nature. Excellent yields of the targeted molecules have been obtained.

scholarly journals Asymmetric Addition of Allylsilanes to Aldehydes – A Cr/Photoredox Dual Catalytic Approach Complementing the Hosomi–Sakurai Reaction

2021 ◽  
Author(s):  
Felix Schäfers ◽  
Subhabrata Dutta ◽  
Roman Kleinmans ◽  
Christian Mück-Lichtenfeld ◽  
Frank Glorius
Keyword(s):  
Organic Chemistry ◽  
Transition State ◽  
Bioactive Compound ◽  
General Strategy ◽  
Acid Activation ◽  
Mechanistic Studies ◽  
Mild Conditions ◽  
Homoallylic Alcohols ◽  
Synthetic Utility ◽  
Fundamental Transformation

The allylation of aldehydes is a fundamental transformation in synthetic organic chemistry. Among the multitude of available reagents, especially allylsilanes have been established as preferred allyl source. As initially reported by Hosomi & Sakurai, these non-toxic and highly stable reagents add to carbonyls via an open transition state upon Lewis acid activation. Herein, we report a general strategy to access a variety of valuable homoallylic alcohols in opposite chemo- and diastereoselectivity to the established Hosomi–Sakurai conditions by switching to photocatalytic activation in combination with a closed transition state (Chromium catalysis). Moreover, this dual catalytic approach displays a straightforward way to introduce excellent levels of enantioselectivity and its mild conditions allow for a broad substrate scope including chiral boron-substituted products as a highlight. To emphasize the synthetic utility, our method was applied as the key step in the synthesis of a bioactive compound and in the late-stage functionalization of steroid derivatives. Detailed mechanistic studies and DFT calculations hint towards an unprecedented photo-initiated chain being operative.

Brønsted acid-catalyzed 1,2-fluorine migration with fluoroepoxides

2015 ◽  
Vol 44 (45) ◽  
pp. 19636-19641 ◽  
Author(s):  
Tao Luo ◽  
Rui Zhang ◽  
Xiao Shen ◽  
Wei Zhang ◽  
Chuanfa Ni ◽  
...  
Keyword(s):  
Fluorine Atom ◽  
Acid Catalysis ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Atom Economy ◽  
Mild Conditions ◽  
Brönsted Acid ◽  
Acid Catalyzed ◽  
Bronsted Acid Catalysis

An efficient 1,2-fluorine migration reaction was realized under Brønsted acid catalysis in the absence of an external fluorinating source. The high fluorine atom economy and very mild conditions make this reaction a promising protocol for the construction of the C–F bond.

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