Photoinduced decarboxylative borylation of carboxylic acids

Fawcett, Alexander; Pradeilles, Johan A.; Wang, Yahui; Mutsuga, Tatsuya; Myers, Eddie L.; Aggarwal, Varinder K.

doi:10.1126/science.aan3679

Cited by 546 publications

(283 citation statements)

References 67 publications

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“…Our studies began by examining known boron‐based EDA complex donors in combination with Katritzky salt 2 a . Pleasingly, we observed the appearance of a significant color change when dissolving Katritzky salt 2 a and B 2 cat 2 in DMA, which was a strong indicator that the Katritzky salts could indeed undergo the desired EDA complex formation.…”

Section: Methodsmentioning

confidence: 98%

Deaminative Borylation of Aliphatic Amines Enabled by Visible Light Excitation of an Electron Donor–Acceptor Complex

Sandfort

Strieth‐Kalthoff

Klauck

et al. 2018

Chemistry A European J

200

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A deaminative strategy for the borylation of aliphatic primary amines is described. Alkyl radicals derived from the single‐electron reduction of redox‐active pyridinium salts, which can be isolated or generated in situ, were borylated in a visible light‐mediated reaction with bis(catecholato)diboron. No catalyst or further additives were required. The key electron donor–acceptor complex was characterized in detail by both experimental and computational investigations. The synthetic potential of this mild protocol was demonstrated through the late‐stage functionalization of natural products and drug molecules.

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Section: Methodsmentioning

confidence: 98%

Deaminative Borylation of Aliphatic Amines Enabled by Visible Light Excitation of an Electron Donor–Acceptor Complex

Sandfort

Strieth‐Kalthoff

Klauck

et al. 2018

Chemistry A European J

200

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“…Extension to a decarboxylative carbon-heteroatom, particularly C-B bond formation has also been reported 19,[25][26][27][28][29] . The key attributes of alkyl carboxylic acids 30,31 are their unparalleled availability, stability and non-toxic nature, which are in stark contrast with alkyl halides, ketones and aldehydes.…”

mentioning

confidence: 78%

Decarboxylative C(sp3)–N cross-coupling via synergetic photoredox and copper catalysis

et al. 2018

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A mines are one of the most important structural motifs in pharmaceuticals, agrochemicals and organic materials 1,2 . Alkylation and reductive amination reactions are still commonly used to prepare and modify amines, and new methods derived from reductive amination, such as the borrowing hydrogen 3 strategy, have been reported [4][5][6][7] . Nevertheless, the most significant development in amine synthesis has been transition-metal-catalysed C-N coupling of aryl electrophiles (halides and pseudo halides) with amine nucleophiles [8][9][10][11] (Fig. 1a). The C-N coupling of alkyl electrophiles, however, is largely under-developed (Fig. 1a). A perceived difficulty is β -hydrogen elimination from a metal alkyl intermediate originated from oxidative addition of the alkyl electrophile, which has posed considerable challenges in analogous C-C crosscoupling of alkyl electrophiles [12][13][14] . Moreover, the product-yielding C(sp 3 )-N reductive elimination step is rarely demonstrated 15 . A notable exception is the light-induced, copper-catalysed C-N coupling of alkyl halides recently developed [16][17][18] . Nevertheless, the scope of amine nucleophiles is limited to carbazoles 16,18 and amides 17,19 . Alternative, formal C-N coupling of alkyl electrophiles via the addition of alkyl radicals to nitroarenes has been reported 20,21 .The group of Baran has recently trailblazed the use of redox-active esters derived from alkyl carboxylic acids as superior surrogates of alkyl halides in decarboxylative C-C cross-coupling reactions [22][23][24] . Extension to a decarboxylative carbon-heteroatom, particularly C-B bond formation has also been reported 19,[25][26][27][28][29] . The key attributes of alkyl carboxylic acids 30,31 are their unparalleled availability, stability and non-toxic nature, which are in stark contrast with alkyl halides, ketones and aldehydes. While several precedents of decarboxylative imidation 32 and amination 19,33 are known, they are limited to a narrow scope of very special substrates or intramolecular reactions. A general metal-catalysed decarboxylative C-N coupling of redox-active esters with anilines will provide valuable methodology for the synthesis of alkylated anilines (Fig. 1b), which requires alkyl halides and carbonyl compounds 6 as starting reagents using the currently standard methods of alkylation and reductive amination, respectively. Further foreseen advantages of such a decarboxylative amination include applicability to bulky primary and secondary alkyl groups and immunity to over-alkylation, both of which are major limitations of direct alkylation (Fig. 1b). Despite its conceptual simplicity and resemblance to decarboxylative C-C coupling, the intermolecular decarboxylative C-N coupling of redoxactive esters poses significant hurdles. The activation principle of redox-active esters originates from amide-bond synthesis; thus, amide formation can compete when amine nucleophiles are used. Moreover, decarboxylative C-C coupling reactions of redox-active esters were, until now, all init...

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“…In mid‐2017, Aggarwal and coworkers reported a complimentary, transition‐metal free, photoinduced decarboxylative borylation strategy for the conversion of NHPI esters into the corresponding pinacol boronate esters through irradiation with visible light . Although not demonstrated explicitly on peptide substrates, the successful decarboxylative borylation of a glutamic acid side‐chain suggests that this methodology may be similarly extendable to the late‐stage modification of peptides.…”

Section: Decarboxylation Of Activated Estersmentioning

confidence: 99%

Decarboxylative couplings as versatile tools for late‐stage peptide modifications

Malins

2018

Peptide Science

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While strategies for the late‐stage modification of peptides are crucial to the design and synthesis of new peptide‐based materials and therapeutics, synthetic methods have historically focused on the modification of select, nucleophilic amino acids. This review highlights decarboxylative coupling strategies as emerging tools for the targeted functionalization of native peptidic acids—α‐carboxylic acids and aspartic/glutamic acid residues—through complexity building CC and Cheteroatom bond formations. Decarboxylation strategies employing both activated carboxylic acids (redox‐active esters) and the direct application of unprotected carboxylic acids are discussed. Emphasis is placed on the scope and limitations of the methodologies as well as their compatibility with complex peptide substrates.

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Photoinduced decarboxylative borylation of carboxylic acids

Cited by 546 publications

References 67 publications

Deaminative Borylation of Aliphatic Amines Enabled by Visible Light Excitation of an Electron Donor–Acceptor Complex

Deaminative Borylation of Aliphatic Amines Enabled by Visible Light Excitation of an Electron Donor–Acceptor Complex

Decarboxylative C(sp3)–N cross-coupling via synergetic photoredox and copper catalysis

Decarboxylative couplings as versatile tools for late‐stage peptide modifications

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