Base-Mediated Site-Selective Hydroamination of Alkenes

Synthesis ◽  
2021 ◽  
Author(s):  
Ping Li ◽  
Boon Chong Lee ◽  
Xiaoxiang Zhang ◽  
Ming Joo Koh
Keyword(s):  
Mild Conditions ◽  
Aryl Amines ◽  
Mechanistic Investigations ◽  
Site Selective

We present a base-mediated hydroamination protocol, using substoichiometric amounts of a hydrosilane and potassium tert-butoxide, that operates under mild conditions at 30 oC. Many aryl- and heteroatom-substituted olefins as well as aryl amines are tolerated, affording the desired products with complete regioselectivity. Preliminary mechanistic investigations reveal a non-radical pathway for hydroamination. A sequential remote hydroamination strategy involving an initial Fe-catalysed olefin isomerisation followed by our base-mediated hydroamination was also developed to directly access β-arylamines from terminal aliphatic alkenes.

Direct incorporation of [ 18F] into aliphatic systems: A promising Mncatalysed labelling technique for PET imaging

2020 ◽  
Vol 13 ◽  
Author(s):  
Sara Cesarec ◽  
Jonathan A. Robson ◽  
Laurence S. Carroll ◽  
Eric O. Aboagye ◽  
Alan C. Spivey
Keyword(s):  
Positron Emission Tomography ◽  
Pet Imaging ◽  
Emission Tomography ◽  
Labelling Technique ◽  
Porphyrin Complex ◽  
Mild Conditions ◽  
Drug Substances ◽  
Positron Emission ◽  
Site Selective ◽  
Direct Incorporation

Background: One of the challenges in positron emission tomography (PET) is labelling complex aliphatic molecules. Objective: To develop a method of metal-catalysed radiofluorination that is site-selective and works in moderate to good yields under facile conditions. Methods: We report here on the optimisation of an aliphatic C-H to C-18F bond transformation catalysed by a Mn(porphyrin) complex. Results: The successful oxidation of 11 aliphatic molecules including progesterone are reported. Radiochemical Incorporations (RCIs) up to 69% were achieved within 60 min without the need for pre-activation or specialist equipment. Conclusion: The method features mild conditions (60 °C) and promises to constitute a valuable approach to labelling of biomolecules and drug substances.

Organophosphane-Catalyzed Construction of Functionalized 2-Ylideneoxindoles via Direct β-Acylation

Synthesis ◽  
2021 ◽  
Author(s):  
Wey-Chyng Jeng ◽  
Po-Chung Chien ◽  
Sandip Sambhaji Vagh ◽  
Athukuri Edukondalu ◽  
Wenwei Lin
Keyword(s):  
Intramolecular Cyclization ◽  
Efficient Method ◽  
Bond Cleavage ◽  
Scale Up ◽  
Acyl Chlorides ◽  
Metal Free ◽  
Mild Conditions ◽  
Synthetic Utility ◽  
Mechanistic Investigations ◽  
Synthetic Transformations

We report an efficient method for the direct β-acylation of 2-ylideneoxindoles with acyl chlorides in the presence of base-catalyzed by organophosphanes. A variety of functionalized 2-ylideneoxindoles were prepared in moderate to good yields under metal-free and mild conditions via a tandem phospha-Michael/O-acylation/intramolecular cyclization/ rearrangement sequence. The mechanistic investigations revealed that the C-O bond cleavage on possible betaine intermediate is the key step for the installation of keto-functionality at β-position of 2-ylideneoxindoles in a highly stereospecific manner. The synthetic utility of this protocol could also be proven by scale-up reactions and synthetic transformations of the products.

scholarly journals Bioinspired Thiophosphorodichloridate Reagents for Chemoselective Histidine Bioconjugation

2018 ◽  
Author(s):  
Shang Jia ◽  
Christopher Chang
Keyword(s):  
Protein Function ◽  
Living Cells ◽  
Covalent Modification ◽  
Native Protein ◽  
Selective Labeling ◽  
Protein Residues ◽  
Mild Conditions ◽  
Starting Point ◽  
Histidine Phosphorylation ◽  
Site Selective

Site-selective bioconjugation to native protein residues is a powerful tool for protein functionalization, with cysteine and lysine side chains being the most common points for attachment owing to their high nucleophilicity. We now report a strategy for histidine modification using thiophosphorodichloridate reagents that mimic post-translational histidine phosphorylation, enabling fast and selective labeling of protein histidines under mild conditions where various payloads can be introduced via copper-assisted alkyne-azide cycloaddition (CuAAC) chemistry. We establish that these reagents are particularly effective at covalent modification of His-tags, which are common motifs to facilitate protein purification, as illustrated by selective attachment of polyarginine cargoes to enhance the uptake of proteins into living cells. This work provides a starting point for probing and enhancing protein function using histidine-directed chemistry.

scholarly journals Enantioenriched Quaternary α-Pentafluoroethyl Derivatives of Alkyl 1-Indanone-2-Carboxylates

2020 ◽  
Author(s):  
Albert Granados ◽  
Anna Balleteros ◽  
Adelina Vallribera
Keyword(s):  
Hypervalent Iodine ◽  
Catalytic Method ◽  
Quaternary Centers ◽  
Mild Conditions ◽  
Reaction Proceeds ◽  
Mechanistic Investigations ◽  
Derivatives Of

An electrophilic enantioselective catalytic method for the a-pentafluoroethylation of alkyl 1-indanone-2-carboxylates is described. Under the use of La(OTf)<sub>3</sub> in combination with (<i>S,R</i>)-indanyl-<i>pybox</i> ligand good results in terms of yield and enantioselectivities were achieved (up to 89% <i>ee</i>). The reaction proceeds under mild conditions leading to the formation of enantioenriched quaternary centers. This methodology uses an hypervalent iodine(III)-CF<sub>2</sub>CF<sub>3</sub> reagent and mechanistic investigations are consistent with the involvement of a radical pathway.

Nitroacenaphthene as a New Photocatalyst for the Synthesis of Sulfonyl Amidines

Synthesis ◽  
2019 ◽  
Vol 51 (23) ◽  
pp. 4425-4433
Author(s):  
Yong Jian ◽  
Ming Chen ◽  
Chao Yang ◽  
Wujiong Xia
Keyword(s):  
Visible Light ◽  
Small Molecule ◽  
Reaction Pathways ◽  
Visible Light Photocatalyst ◽  
Mild Conditions ◽  
Sulfonyl Azides ◽  
Site Selective ◽  
First Time

A small molecule, namely nitroacenaphthene, is reported for the first time as a recyclable visible-light photocatalyst for the construction of the C=N bond from sulfonyl azides and amines. This scalable, site-selective protocol provides a convenient way to access various sulfonyl amidines under mild conditions. Two reaction pathways are proposed, according to different transformation patterns.

ChemInform Abstract: Cu(II)-Catalyzed Direct and Site-Selective Arylation of Indoles under Mild Conditions.

ChemInform ◽  
2008 ◽  
Vol 39 (44) ◽  
Author(s):  
Robert J. Phipps ◽  
Neil P. Grimster ◽  
Matthew J. Gaunt
Keyword(s):  
Mild Conditions ◽  
Site Selective

scholarly journals Bioinspired Thiophosphorodichloridate Reagents for Chemoselective Histidine Bioconjugation

2018 ◽  
Author(s):  
Shang Jia ◽  
Christopher Chang
Keyword(s):  
Protein Function ◽  
Living Cells ◽  
Covalent Modification ◽  
Native Protein ◽  
Selective Labeling ◽  
Protein Residues ◽  
Mild Conditions ◽  
Starting Point ◽  
Histidine Phosphorylation ◽  
Site Selective

Site-selective bioconjugation to native protein residues is a powerful tool for protein functionalization, with cysteine and lysine side chains being the most common points for attachment owing to their high nucleophilicity. We now report a strategy for histidine modification using thiophosphorodichloridate reagents that mimic post-translational histidine phosphorylation, enabling fast and selective labeling of protein histidines under mild conditions where various payloads can be introduced via copper-assisted alkyne-azide cycloaddition (CuAAC) chemistry. We establish that these reagents are particularly effective at covalent modification of His-tags, which are common motifs to facilitate protein purification, as illustrated by selective attachment of polyarginine cargoes to enhance the uptake of proteins into living cells. This work provides a starting point for probing and enhancing protein function using histidine-directed chemistry.

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