Boron Trifluoride Etherate

Cornel, Veronica M.; Lovely, Carl J.

doi:10.1002/9780470842898.rb249.pub2

Cited by 5 publications

(4 citation statements)

References 216 publications

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“…Having started with ordinary boron hydrides, the utility of boron-containing compounds has surpassed all early expectations. The already mentioned hydroboration, which is often followed by a subsequent oxidation process, [3] the cross-coupling reactions involving boronic acids and esters, [4] the use of boron enolates in aldol reactions,5 the utilization of boron halides as strong Lewis acids [6] and dealkylation reagents, [7] the enantioselective reductions of prochiral carbonyl compounds with boranes, [8] trifluoroborates and their unique synthetic characteristics, [9] and many other reactions underscore the potential of boron compounds in organic synthesis. Many reviews can be found on the subject, including those covering some recent advances in the field.…”

Section: Introductionmentioning

confidence: 99%

Coordination Chemistry of Borane in Solution: Application to a STING Agonist

2022

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Equilibrium constants were determined for ligand exchange reactions of borane complexes with various oxygen, sulfur, nitrogen, and phosphorus nucleophiles in solution, and a binding affinity scale was built spanning a range of 12 orders of magnitude. While the K eq are minimally dependent on the solvent, the rate of ligand exchange varies significantly. The fastest and slowest rates were observed in THF and CDCl 3 , respectively. Moreover, the ligand exchange rate differs in a very broad range depending on stability of the starting complex. Binding of BH 3 was found to be much more sensitive to steric factors than protonation. Comparing nitrogen bases having equal steric properties, a linear correlation of BH 3 binding affinity vs. Brønsted acidity was found. This correlation can be used to quickly estimate the BH 3 binding affinity of a substrate if pK a is known. Kinetic studies suggest the ligand exchange to occur as a bimolecular S N 2 reaction unless other nucleophilic species were present in the reaction mixture.

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Section: Introductionmentioning

confidence: 99%

Coordination Chemistry of Borane in Solution: Application to a STING Agonist

2022

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“…When no Lewis acid was used, the formation of a side product, cinnamyl 2-oxo-2-( p -tolylamino)acetate 7a , was detected in 42% yield (Table , entry 5). To further optimize the yield and to avoid the moisture- and air-sensitive BF 3 ·Et 2 O, many different Lewis and Brønsted acids were screened (Table , entry 6–30). First, the easier to handle and heterogeneous BF 3 @silica was used, which also gave acceptable yields (Table , entry 6).…”

Section: Results and Discussionmentioning

confidence: 99%

“…When no Lewis acid was used, the formation of a side product, cinnamyl 2-oxo-2-(p-tolylamino)acetate 7a, was detected in 42% yield (Table 1, entry 5). To further optimize the yield and to avoid the moisture-and airsensitive BF 3 •Et 2 O, 53 many different Lewis and Brønsted acids were screened (Table 1, entry 6−30). First, the easier to handle With the optimal conditions at hand, the scope of the reaction was examined by reacting a wide range of substrates 1a−m with both electron-withdrawing (F, CF 3 , Br, I) and electron-donating (OMe, Me) substituents in various positions (ortho-, meta-, and para-).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Engineering of Phenylpyridine- and Bipyridine-Based Covalent Organic Frameworks for Photocatalytic Tandem Aerobic Oxidation/Povarov Cyclization

Debruyne

Borgmans

Radhakrishnan

et al. 2023

ACS Appl. Mater. Interfaces

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Covalent organic frameworks (COFs) are emerging as a new class of photoactive organic semiconductors, which possess crystalline ordered structures and high surface areas. COFs can be tailor-made toward specific (photocatalytic) applications, and the size and position of their band gaps can be tuned by the choice of building blocks and linkages. However, many types of building blocks are still unexplored as photocatalytic moieties and the scope of reactions photocatalyzed by COFs remains quite limited. In this work, we report the synthesis and application of two bipyridine- or phenylpyridine-based COFs: TpBpyCOF and TpPpyCOF. Due to their good photocatalytic properties, both materials were applied as metal-free photocatalysts for the tandem aerobic oxidation/Povarov cyclization and α-oxidation of N-aryl glycine derivatives, with the bipyridine-based TpBpyCOF exhibiting the highest activity. By expanding the range of reactions that can be photocatalyzed by COFs, this work paves the way toward the more widespread application of COFs as metal-free heterogeneous photocatalysts as a convenient alternative for commonly used homogeneous (metal-based) photocatalysts.

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“…Treatment of the 1,2-diaminoalkene 17a with a selection of dehydrating/acidic reagents; including p -toluene sulfonic acid, trimethylsilyl triflate, acetic acid, and phosphorus oxychloride resulted in the decomposition of substrate with only a minimal amount of the desired pyrrole 18a . Gratifyingly, using BF 3 ·OEt 2 35 (0.5 equiv) in dichloromethane at 80 °C gave a modest 49% yield of pyrrole 18a ( Table 2 , entry 1) with a cleaner reaction profile ( 1 H NMR). Increasing the amount of Lewis acid from 0.5 to 3.0 equiv was accompanied by an increase in yield to 72% (entries 2 and 3).…”

Section: Resultsmentioning

confidence: 99%

Modular Synthesis of Highly Substituted 3-Azapyrroles by Rh(II)-Catalyzed N–H Bond Insertion and Cyclodehydration

Williams

Boyer

2022

J. Org. Chem.

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A modular synthesis of highly substituted 3azapyrroles has been developed using a three-step sequence comprising copper-catalyzed alkyne−azide cycloaddition (CuAAC), N−H bond insertion, and cyclodehydration. 1-Sulfonyl-1,2,3-triazoles (1-STs) can be accessed from common alkyne and sulfonyl azide building blocks by CuAAC using CuTC. Rhodium(II)-acetate-promoted 1-ST denitrogenation results in highly electrophilic rhodium azavinyl carbenes that, here, underwent insertion into the N−H bond of secondary α-aminoketones to form 1,2-aminoalkenes. These products were cyclized and dehydrated using BF 3 •OEt 2 into highly substituted 3-azapyrroles. The three steps (CuAAC, N−H bond insertion, and cyclodehydration) could be telescoped into a one-pot process. The method proved to be highly efficient and tolerated a wide range of substituents.

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Boron Trifluoride Etherate

Cited by 5 publications

References 216 publications

Coordination Chemistry of Borane in Solution: Application to a STING Agonist

Coordination Chemistry of Borane in Solution: Application to a STING Agonist

Engineering of Phenylpyridine- and Bipyridine-Based Covalent Organic Frameworks for Photocatalytic Tandem Aerobic Oxidation/Povarov Cyclization

Modular Synthesis of Highly Substituted 3-Azapyrroles by Rh(II)-Catalyzed N–H Bond Insertion and Cyclodehydration

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