Unlocking the Accessibility of Alkyl Radicals from Boronic Acids through Solvent-Assisted Organophotoredox Activation

ACS Catalysis ◽  
2021 ◽  
Vol 11 (17) ◽  
pp. 10862-10870 ◽  
Author(s):  
Prabhat Ranjan ◽  
Serena Pillitteri ◽  
Guglielmo Coppola ◽  
Monica Oliva ◽  
Erik V. Van der Eycken ◽  
...  
Keyword(s):  
Boronic Acids ◽  
Alkyl Radicals

scholarly journals Unlocking the Accessibility of Alkyl Radicals from Boronic Acids through Hydrogen-bond Assisted Organophotoredox Activation

2021 ◽  
Author(s):  
Prabhat Ranjan ◽  
Serena Pillitteri ◽  
Guglielmo Coppola ◽  
Monica Oliva ◽  
Erik V. Van der Eycken ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Unnatural Amino Acids ◽  
Alkyl Radical ◽  
Boronic Acids ◽  
Oxidation Potential ◽  
Radical Species ◽  
Alkyl Radicals ◽  
Hydrogen Bonding Interactions ◽  
High Oxidation ◽  
Selective Generation

Despite their prevalence in organic synthesis, the application of boronic acids (BAs) as alkyl radical precursors in visible-light assisted photocatalyzed reactions has been limited by their high oxidation potential. This study demonstrates the remarkable ability of amide solvents viz. DMA (N,N-dimethylacetamide) to participate in hydrogen-bonding interactions with BAs, thus enabling the modulation of their oxidation potential towards the generation of alkyl radicals. The developed protocol is simple, robust and demonstrates broad applicability for alkylation, allylation and elimination reactions in batch and continuous flow. The application towards dehydroalanine allows the synthesis of unnatural amino acids. Furthermore, the chemo-selective generation of radical species from BAs, in the presence of boronic ester-containing molecules, is now feasible, endorsing plausible boron-selective (bio-) orthogonal modifications.

scholarly journals Unlocking the Accessibility of Alkyl Radicals from Boronic Acids through Hydrogen-bond Assisted Organophotoredox Activation

2021 ◽  
Author(s):  
Prabhat Ranjan ◽  
Serena Pillitteri ◽  
Guglielmo Coppola ◽  
Monica Oliva ◽  
Erik V. Van der Eycken ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Unnatural Amino Acids ◽  
Alkyl Radical ◽  
Boronic Acids ◽  
Oxidation Potential ◽  
Radical Species ◽  
Alkyl Radicals ◽  
Hydrogen Bonding Interactions ◽  
High Oxidation ◽  
Selective Generation

Despite their prevalence in organic synthesis, the application of boronic acids (BAs) as alkyl radical precursors in visible-light assisted photocatalyzed reactions has been limited by their high oxidation potential. This study demonstrates the remarkable ability of amide solvents viz. DMA (N,N-dimethylacetamide) to participate in hydrogen-bonding interactions with BAs, thus enabling the modulation of their oxidation potential towards the generation of alkyl radicals. The developed protocol is simple, robust and demonstrates broad applicability for alkylation, allylation and elimination reactions in batch and continuous flow. The application towards dehydroalanine allows the synthesis of unnatural amino acids. Furthermore, the chemo-selective generation of radical species from BAs, in the presence of boronic ester-containing molecules, is now feasible, endorsing plausible boron-selective (bio-) orthogonal modifications.

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

A Mild and Simple Method for Making MIDA Boronates

2020 ◽  
Author(s):  
Aidan Kelly ◽  
Peng-Jui (Ruby) Chen ◽  
Jenna Klubnick ◽  
Daniel J. Blair ◽  
Martin D. Burke
Keyword(s):  
Organic Synthesis ◽  
Boronic Acids ◽  
Simple Method ◽  
Direct Preparation ◽  
Synthesis Procedure ◽  
Harsh Conditions

<div> <div> <div> <p>Existing methods for making MIDA boronates require harsh conditions and complex procedures to achieve dehydration. Here we disclose that a pre-dried form of MIDA, MIDA anhydride, acts as both a source of the MIDA ligand and an in situ desiccant to enable a mild and simple MIDA boronate synthesis procedure. This method expands the range of sensitive boronic acids that can be converted into their MIDA boronate counterparts. Further utilizing unique properties of MIDA boronates, we have developed a MIDA Boronate Maker Kit which enables the direct preparation and purification of MIDA boronates from boronic acids using only heating and centrifuge equipment that is widely available in labs that do not specialize in organic synthesis. </p> </div> </div> </div>

Visible-Light Photosensitized Aryl and Alkyl Decarboxylative Carbon-Heteroatom and Carbon-Carbon Bond Formations

2019 ◽  
Author(s):  
Tuhin Patra ◽  
Satobhisha Mukherjee ◽  
Jiajia Ma ◽  
Felix Strieth-Kalthoff ◽  
Frank Glorius
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Alkyl Radical ◽  
General Strategy ◽  
Alkyl Radicals ◽  
Bond Forming ◽  
Radical Trapping ◽  
Carbon Carbon Bond ◽  
Radical Generation ◽  
Trapping Agent

<sub>A general strategy to access both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters has been developed. An energy transfer mediated homolysis of unsymmetrical sigma-bonds for a concerted fragmentation/decarboxylation process is involved. As a result, an independent aryl/alkyl radical generation step enables a series of key C-X and C-C bond forming reactions by simply changing the radical trapping agent.</sub>

Neoglycopeptide Synthesis by Suzuki-Miyaura Couplings between Glycosyl Aryl Boronic Acids and Iodopeptides

2014 ◽  
Vol 21 (10) ◽  
pp. 1004-1010
Author(s):  
Guohua Chen ◽  
Xiangying Gu ◽  
Lin Chen ◽  
Xin Wang ◽  
Yue-Lei Chen ◽  
...  
Keyword(s):  
Boronic Acids

Addition of Boronic Acids to Cyclic Sulfonylketimines

Synfacts ◽  
2015 ◽  
Vol 11 (12) ◽  
pp. 1316-1316
Keyword(s):  
Boronic Acids

The Merger of CF3SO2Na and Palladium Catalysis to Enable Decarboxylative Cross-Coupling for the Synthesis of Aromatic Ketones under Room Temperature

2021 ◽  
Author(s):  
Pan Xie ◽  
Cheng Xue ◽  
Cancan Wang ◽  
Dongdong Du ◽  
Sanshan Shi
Keyword(s):  
Visible Light ◽  
Room Temperature ◽  
Palladium Catalysis ◽  
Cross Coupling ◽  
Boronic Acids ◽  
Aromatic Ketones ◽  
Aryl Ketones ◽  
Oxocarboxylic Acids

A CF3SO2Na/Pd(OAc)2 co-catalyzed strategy is developed to produce aryl ketones via visible-light-induced decarboxylative cross-coupling of α-oxocarboxylic acids and aryl boronic acids. This process was perfomed under air at room temperature,...

Sign in / Sign up

Export Citation Format

Share Document