ChemInform Abstract: Frustrated Lewis Pair‐Catalyzed Cycloisomerization of 1,5‐Enynes via a 5‐endo‐dig Cyclization/Protodeborylation Sequence.

Tamke, Sergej; Qu, Zheng‐Wang; Sitte, Nikolai A.; Floerke, U.; Paradies, Jan

doi:10.1002/chin.201630114

Cited by 3 publications

(3 citation statements)

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“…Cyclization of 1,5-enynes to produce functionalized indenes was found to be possible in a metal-free pathway using B(C 6 F 5 ) 3 as a catalyst as part of an FLP. 76 The reaction was found to be cycloisomerization, with π activation of the alkyne by B(C 6 F 5 ) 3 and 5-endo-dig cyclization with the alkene, forming a borylated indene, which undergoes protodeboronation, generating 62 (Scheme 38). The use of an FLP system with B(C 6 F 5 ) 3 and Lewis base (PPh 3 ) was found to be necessary for a catalytic system because the protodeboronation step is key to achieving a catalytic turnover.…”

Section: ■ Elementoboration Reactionsmentioning

confidence: 99%

Tris(pentafluorophenyl)borane and Beyond: Modern Advances in Borylation Chemistry

2017

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As main-group chemistry, in particular boron chemistry, has expanded and developed over the past 20 years, one reagent has risen to prominence as well. Tris(pentafluorophenyl)borane, B(CF) (commonly known as BCF), has demonstrated extensive applications in a wide variety of reactions, including borylation, hydrogenation, hydrosilylation, frustrated Lewis pair (FLP) chemistry, Lewis acid catalysis, and more. The high Lewis acidity of B(CF) is derived from the electronic effects of its three CF rings, rendering it a versatile reagent for a great number of reactions. In addition, the steric bulk of these rings also allows it to function as the Lewis acid in a FLP, granting this reagent yet another synthetically useful application. However, as main-group chemistry continues to evolve as a field, new reagents are required that go beyond BCF, increasing not only the range of reactions available but also the breadth of compounds attainable. Great strides have already been made in order to accomplish this task, and this review will highlight modern advances in boron chemistry relating to borylation reactions. Herein, we will show the recent uses of B(CF) in borylation reactions while also focusing on current advances in novel borane and borocation usage that eclipses that of the stalwart B(CF).

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Section: ■ Elementoboration Reactionsmentioning

confidence: 99%

Tris(pentafluorophenyl)borane and Beyond: Modern Advances in Borylation Chemistry

2017

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“…123−134 Such reactions in many cases mirror transformations accessible typically via carbophillic Au or Pt catalysts. 111 An exemplary cyclization of a 1,5-enyne 124 is presented in Figure 8, which may be accessed via either boron-or gold-based catalysis. Triphenylphosphine is also added in this case to act as a proton shuttle.…”

Section: Alkynesmentioning

confidence: 99%

Metallomimetic Chemistry of Boron

2019

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The study of main-group molecules that behave and react similarly to transition metal (TM) complexes has attracted significant interest in the recent decades. Most notably, the attractive idea of eliminating the all-too-often rare and costly metals from catalysis has motivated efforts to develop main-group-element-mediated reactions. Main-group elements, however, lack the electronic flexibility of many TM complexes that arise from combinations of empty and filled d-orbitals and that seem ideally suited to bind and activate many substrates. In this Review, we look at boron, an element which, despite its non-metal nature, low atomic weight, and relative redox staticity has achieved great milestones in terms of TM-like reactivity. We show how in inter-element cooperative systems, diboron molecules and hypovalent complexes, the fifth element can acquire a truly metallomimetic character. As we discuss, this character is particularly strikingly demonstrated by the reactivity of boron-based molecules with H2, CO, alkynes, alkenes and even with N2.

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“…The B(C 6 F 5 ) 3 cocatalyst then activates the Pd(0)/enyne complex II to yield the outer-sphere oxidative addition adduct III. Complex III subsequently undergoes a protodeboronation 28 by an ammonium cation species (originating from a deprotonative activation of terminal alkyne in the Cu cycle to generate the Cu-alkynyl 29 species) to form IV with concomitant release of the B(C 6 F 5 ) 3 cocatalyst. Transmetalation of the Cu-alkynl species (from Cu cycle) to IV affords intermediate V, which upon reductive elimination delivers the product and regenerates the Pd catalyst I.…”

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confidence: 99%

trans-Hydroalkynylation of Internal 1,3-Enynes Enabled by Cooperative Catalysis

Wang

Zhang

et al. 2023

J. Am. Chem. Soc.

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A cooperative catalyst system involving a Pd(0)/Senphos complex, tris(pentafluorophenyl)borane, copper bromide, and an amine base, is demonstrated to catalyze trans-hydroalkynylation of internal 1,3-enynes. For the first time, a Lewis acid catalyst is shown to promote the reaction involving the emerging outer-sphere oxidative reaction step. The resulting cross-conjugated dieneynes are versatile synthons for organic synthesis, and their characterization reveals distinct photophysical properties depending on the positioning of the donor/acceptor substituents along the conjugation path.

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ChemInform Abstract: Frustrated Lewis Pair‐Catalyzed Cycloisomerization of 1,5‐Enynes via a 5‐endo‐dig Cyclization/Protodeborylation Sequence.

Cited by 3 publications

References 1 publication

Tris(pentafluorophenyl)borane and Beyond: Modern Advances in Borylation Chemistry

Tris(pentafluorophenyl)borane and Beyond: Modern Advances in Borylation Chemistry

Metallomimetic Chemistry of Boron

trans-Hydroalkynylation of Internal 1,3-Enynes Enabled by Cooperative Catalysis

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