Selective Reduction of Carboxylic Acids to Aldehydes Catalyzed by B(C6F5)3

Bézier, David; Park, Sehoon; Brookhart, Maurice

doi:10.1021/ol303296a

Cited by 94 publications

(47 citation statements)

References 33 publications

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“…The suitable reactivity of hydrosilanes seems to play an important role in the reductive alkylation reaction. Hydrosilanes with poor reactivity failed to reduce formic acid, whereas hydrosilanes with strong reactivity may result in over‐reduction to alcohols . Furthermore, the amount of formic acid and hydrosilane were investigated in detail, and the optimal amounts of formic acid and Et 3 SiH compared with 1 a were 2 and 4.5 equivalents, respectively (entries 4 and 13–15).…”

Section: Resultssupporting

confidence: 73%

“…Several control experiments were conducted to gain further understanding about the reaction mechanism (Scheme ). As it has been shown that the Lewis acid B(C 6 F 5 ) 3 could efficiently catalyze the hydrosilylation of carboxylic acid to produce aldehyde equivalents, that is, disilyl acetal under similar conditions, phenylacetaldehyde was tested as a possible intermediate for the coupling reaction in this study. As a result, nearly quantitative yield of the desired BIM was obtained [Eq.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, boron‐based Lewis acids as catalysts have been widely employed in various reactions . Notably, boron can selectively catalyze the reduction of carboxylic acid to aldehyde, as well as Friedel–Crafts alkylation of an indole with aldehyde to BIM . Inspired by these precedents, it is envisioned that a Lewis acid catalyst might mediate reductive alkylation of indoles with carboxylic acids to obtain BIMs through stringing both selective reduction of carboxylic acid and C−C coupling together.…”

Section: Introductionmentioning

confidence: 99%

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Directly Bridging Indoles to 3,3′‐Bisindolylmethanes by Using Carboxylic Acids and Hydrosilanes under Mild Conditions

Qiao

Liu

et al. 2018

Chemistry An Asian Journal

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A straightforward Lewis acid-promoted protocol for 3,3'-bisindolylmethanes (BIMs) synthesis by reductive alkylation of indoles at the C3 position with carboxylic acids in the presence of hydrosilane was developed for the first time. Instead of aldehydes, more readily available, stable, and easy-to-handle carboxylic acids have been employed as alternative alkylating agents. As an efficient organocatalyst, B(C F ) enables the reductive alkylation of various substituted indole derivatives with carboxylic acids with up to 98 % yield at room temperature and under neat conditions. This metal-free strategy offers an alternative approach for the direct functionalization of indoles to BIMs with carboxylic acids and such protocol allows selective reduction of carboxylic acid to aldehyde in combination with C-C bond formation.

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Section: Resultssupporting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Directly Bridging Indoles to 3,3′‐Bisindolylmethanes by Using Carboxylic Acids and Hydrosilanes under Mild Conditions

Qiao

Liu

et al. 2018

Chemistry An Asian Journal

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“…Hydrosilanes are convenient reagents in reduction reactions thanks to their polarized Si−H bond, which make them good hydride donors . They can be used in multiple reduction reactions using organometallic complexes or organic catalysts of inorganic salts . Among the most reactive hydrosilanes, silane (or monosilane), SiH 4 , can be obtained from the disproportionation of triethoxysilane (TES).…”

Section: Methodsmentioning

confidence: 99%

Radical‐Initiated Dismutation of Hydrosiloxanes by Catalytic Potassium‐Graphite

et al. 2019

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Formation of higher‐value products from cheaper silicone precursors such as polymethylhydrosiloxane (PMHS) is a challenge for silicon chemistry. Here, we show that catalytic amount (<0.5 mol %) of potassium graphite (KC8) can be used as an efficient radical initiator for the cleavage of Si−O bonds of hydrosiloxanes. Methylsilane and dimethylsilane are quantitatively obtained from PMHS and TMDS (1,1,3,3‐tetramethyldisiloxane), respectively. Taking advantage of the high reactivity of the newly formed silane, the reduction of carbonyl functionalities with KC8 in catalytic amount was further performed. Mechanistic investigations suggest that both the dismutation of the initial hydrosiloxane and the reduction of carbonyl derivatives by hydrosilylation are initiated with a radical pathway.

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“…In the hydrogenation of carboxylic acids with H 2 , many other chemicals can be produced such as alkanes, aldehydes, ketones and esters, which are also valuable chemicals (Scheme ). In general, high yield synthesis of aldehydes from carboxylic acids is very difficult owing to the high reactivity of aldehydes, and hence low temperature transformation with hydrogenation‐active metal catalysts, particularly low active catalysts for hydrogenation (for examples, metal oxides) or use of some special reducing agents except H 2 will be essential to suppress over‐hydrogenation of aldehydes . In contrast, transformation of carboxylic acids (C n ) to alkanes (C n or C n‐1 ) needs high temperature because the reaction requires the dissociation of the strong C−O and C−C bonds.…”

Section: Introductionmentioning

confidence: 99%

Recent Developments of Heterogeneous Catalysts for Hydrogenation of Carboxylic Acids to their Corresponding Alcohols

2020

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Hydrogenation of carboxylic acids is an important organic reaction for the synthesis of alcohols, aldehydes, alkanes, and so on. Selective hydrogenation of carboxylic acids to alcohols is particularly important because alcohols are useful and valuable chemicals. However, the hydrogenation of carboxylic acids is difficult due to the low reactivity of the carboxy group and the acidic property, which require rational design of catalysts. Up to now, various effective homogeneous and heterogeneous catalysts have been intensively developed, and remarkable advances have been made in heterogeneous catalysts. In this minireview, recent progress (2010 and after) on the development of heterogeneous catalysts for hydrogenation of carboxylic acids to alcohols, particularly for monocarboxylic acids to mono primary alcohols, is reviewed. The reported literatures were categorized in terms of catalyst systems, such as monometallic catalysts and bimetallic catalysts. The characteristics, particularly the structure of active sites, reaction mechanism and stability, were introduced.

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Selective Reduction of Carboxylic Acids to Aldehydes Catalyzed by B(C₆F₅)₃

Cited by 94 publications

References 33 publications

Directly Bridging Indoles to 3,3′‐Bisindolylmethanes by Using Carboxylic Acids and Hydrosilanes under Mild Conditions

Directly Bridging Indoles to 3,3′‐Bisindolylmethanes by Using Carboxylic Acids and Hydrosilanes under Mild Conditions

Radical‐Initiated Dismutation of Hydrosiloxanes by Catalytic Potassium‐Graphite

Recent Developments of Heterogeneous Catalysts for Hydrogenation of Carboxylic Acids to their Corresponding Alcohols

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