Trifluoroacetic anhydride—catalyzed conjugate addition of boronic acids to α,β-unsaturated ketones

Roscales, Silvia; Rincón, A.C.; Buxaderas, Eduardo; Csákÿ, Aurelio G.

doi:10.1016/j.tetlet.2012.06.105

Cited by 19 publications

(10 citation statements)

References 41 publications

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“…Indeed, higher stereoselectivity was observed in reactions of β-alkenyl ketone 1g (ref. 42 ) and 1h , and β-alkynyl ketone 1i (ref. 43 ), with dr of 77/23, 86/14 and 93/7, respectively (entries 4–6 versus entry 1, Table 2 ).…”

Section: Resultsmentioning

confidence: 99%

Palladium/N-heterocyclic carbene catalysed regio and diastereoselective reaction of ketones with allyl reagents via inner-sphere mechanism

Bai

Wang

et al. 2016

Nat Commun

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The palladium-catalysed allylic substitution reaction is one of the most important reactions in transition-metal catalysis and has been well-studied in the past decades. Most of the reactions proceed through an outer-sphere mechanism, affording linear products when monosubstituted allyl reagents are used. Here, we report an efficient Palladium-catalysed protocol for reactions of β-substituted ketones with monosubstituted allyl substrates, simply by using N-heterocyclic carbene as ligand, leading to branched products with up to three contiguous stereocentres in a (syn, anti)-mode with excellent regio and diastereoselectivities. The scope of the protocol in organic synthesis has been examined preliminarily. Mechanistic studies by both experiments and density functional theory (DFT) calculations reveal that the reaction proceeds via an inner-sphere mechanism—nucleophilic attack of enolate oxygen on Palladium followed by C–C bond-forming [3,3']-reductive elimination.

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Section: Resultsmentioning

confidence: 99%

Palladium/N-heterocyclic carbene catalysed regio and diastereoselective reaction of ketones with allyl reagents via inner-sphere mechanism

Bai

Wang

et al. 2016

Nat Commun

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“…Reagents and conditions: a) 3 (1 equiv), CH2Cl2, ∆, 4 h -2 days; b) 4 (1.5 equiv), ∆, 16 h -6 days More recently, it has been shown that this type of alkenylation can also be promoted by trifluoroacetic anhydride (TFAA, 0.3 equiv). 5 The experimental procedure is simple (CH 2 Cl 2 , 60 ºC, 18 h) and tolerant of β,β-disubstitution on the enone (65 -90% yield). The use of BF 3 as promoter has been extended to the 1,4-alkynylation of acyclic enones, making use of diisopropoxyboronates (60 -85% yield) or the bench-top stable potassium alkynyltrifluoroborates as reagents (40 -87 % yield).…”

Section: -93%mentioning

confidence: 99%

Transition-metal-free C–C bond forming reactions of aryl, alkenyl and alkynylboronic acids and their derivatives

2014

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Investigation of new methods for the synthesis of C-C bonds is fundamental for the development of new organic drugs and materials. Aryl-, alkenyl- and alkynylboronic acids and their derivatives constitute attractive reagents towards this end, due to their stability, low toxicity and ease of handling. However, these compounds are only moderately nucleophilic. Consequently, the most popular C-C bond forming reactions of these boronic acids, such as the Suzuki-Miyaura, Heck, and Hayashi-Miyaura reactions, or additions to C=O and C=N bonds, require catalysis by transition metals. However, due to the toxicity and cost of transition metals, some new methods for C-C bond formation using aryl-, alkenyl- and alkynylboronic acids under transition-metal-free conditions are beginning to emerge. In this tutorial review, the recent synthetic advances in this field are highlighted and discussed.

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“…A related way for the generation of electron-deficient boron compounds consists of the use of trifluoroacetic anhydride (TFAA). 21 This method has been applied to alkenylboronic acids and to alkenyltrifluoroborates for the diastereoselective synthesis of densely functionalized tetrahydropyrans using as key steps a tandem conjugate additionintramolecular ring opening of cyclic acetals 22a or a tandem conjugate addition-transacetalization. 22b The stereoselectivity of both processes was controlled by the conjugate addition step (Scheme 10).…”

Section: Scheme 8 Radical Addition Of Arylboronic Acids To Quinones 4mentioning

confidence: 99%

C–H Bond Formation with Boronic Acids and Derivatives by Transition-Metal-Free Conjugate Addition Reactions

Csákÿ¹,

Sánchez-Sancho²

2016

Synthesis

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Initially popularized by the Suzuki-Miyaura reaction, boronic acids, boronate esters, and trifluoroborates constitute nowadays essential reagents in CC bond-forming processes. The classic transformations mediated by these reagents require the use of transition metals as catalysts. However, in recent times new reactions in which aryl, alkenyl, and alkynyl derivatives behave as nucleophiles in the absence of transition-metal catalysis have begun to emerge. The purpose of this review is to highlight the most relevant recent advances in CC bond making reactions by conjugate addition of these types of boronic acids under transition-metal-free conditions. 1 Introduction 2 Nucleophilicity of Boronic Acid Derivatives 3 Direct Conjugate Addition Reactions 4 Activation with BF 3 , Cyanuric Fluoride, or TFAA 5 Activation with BINOL Derivatives 6 Activation with Tartaric Acid and Tartaric Acid Derivatives 7 Conclusions

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Trifluoroacetic anhydride—catalyzed conjugate addition of boronic acids to α,β-unsaturated ketones

Cited by 19 publications

References 41 publications

Palladium/N-heterocyclic carbene catalysed regio and diastereoselective reaction of ketones with allyl reagents via inner-sphere mechanism

Palladium/N-heterocyclic carbene catalysed regio and diastereoselective reaction of ketones with allyl reagents via inner-sphere mechanism

Transition-metal-free C–C bond forming reactions of aryl, alkenyl and alkynylboronic acids and their derivatives

C–H Bond Formation with Boronic Acids and Derivatives by Transition-Metal-Free Conjugate Addition Reactions

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