Modified<i>B</i>‐Alkylcatecholboranes as Radical Precursors

Lüthy, M.; Darmency, Vincent; Renaud, Philippe

doi:10.1002/ejoc.201001120

Cited by 35 publications

(18 citation statements)

References 30 publications

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“…Many olefins were compatible with this methodology with use of di‐ tert ‐butylhyponitrile (DTBHN) as radical initiator at 40 °C. Similarly good yields were obtained with use of borane dimethylsulfide complexes and molecular oxygen as radical initiator in place of catecholborane 36. These conditions were also successful for the alkynylation of silyl radicals (from silylboranes) 37…”

Section: Sulfonyl Acetylenes As Alkynylating Reagentsmentioning

confidence: 78%

Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands, meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

Tanase

Otaki

Nishida

et al. 2014

Chemistry A European J

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A series of tetragold(I) complexes supported by tetraphosphine ligands, meso- and rac-bis[(diphenylphosphinomethyl)phenylphosphino]methane (meso- and rac-dpmppm) were synthesized and characterized to show that the tetranuclear Au(I) alignment varies depending on syn- and anti-arrangements of the two dpmppm ligands with respect to the metal chain. The structures of syn-[Au4 (meso-dpmppm)2X]X'3 (X = Cl; X' = Cl (4 a), PF6 (4 b), BF4 (4 c)) and syn-[Au4 (meso-dpmppm)2]X4 (X = PF6 (4 d), BF4 (4 e), TfO (4 f); TfO = triflate) involved a bent tetragold(I) core with a counter anion X incorporated into the bent pocket. Complexes anti-[Au4 (meso-dpmppm)2]X4 (X = PF6 (5 d), BF4 (5 e), TfO (5 f)) contain a linearly ordered Au4 string and complexes syn-[Au4 (rac-dpmppm)2X2]X'2 (X = Cl, X' = Cl (6 a), PF6 (6 b), BF4 (6 c)) and syn-[Au4 (rac-dpmppm)2]X4 (X = PF6 (6 d), BF4 (6 e), TfO (6 f)) consist of a zigzag tetragold(I) chain supported by the two syn-arranged rac-dpmppm ligands. Complexes 4 d-f, 5 d-f, and 6 d-f with non-coordinative large anions are strongly luminescent in the solid state (λmax = 475-515 nm, Φ = 0.67-0.85) and in acetonitrile (λmax = 491-520 nm, Φ = 0.33-0.97); the emission was assigned to phosphorescence from (3) [dσ*σ*σ* pσσσ] excited state of the Au4 centers on the basis of DFT calculations as well as the long lifetime (a few μs). The emission energy is predominantly determined by the HOMO and LUMO characters of the Au4 centers, which depend on the bent (4), linear (5), and zigzag (6) alignments. The strong emissions in acetonitrile were quenched by chloride anions through simultaneous dynamic and static quenching processes, in which static binding of chloride ions to the Au4 excited species should be the most effective. The present study demonstrates that the structures of linear tetranuclear gold(I) chains can be modified by utilizing the stereoisomeric tetraphosphines, meso- and rac-dpmppm, which may lead to fine tuning of the strongly luminescent properties intrinsic to the Au(I) 4 cluster centers.

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Section: Sulfonyl Acetylenes As Alkynylating Reagentsmentioning

confidence: 78%

Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands, meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

Tanase

Otaki

Nishida

et al. 2014

Chemistry A European J

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“…20 Most recently, Renaud has accomplished the coupling of customized catecholboranes to quinones followed by reoxidation. 21 Notably, arylboronic acids have recently been coupled to electron-deficient olefins in excess via a presumed radical mechanism with stoichiometric manganese(III) acetate (no quinone examples given). 22 Inspired by our recent discovery of the silver-catalyzed addition of arylboronic acids to protonated heterocycles, 23 and given the inherent reactivity of quinones with radicals, 1,2 it was reasoned that the same reactive intermediate generated from the boronic acid precursors could interact with other electrophiles such as quinones.…”

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confidence: 99%

Practical C−H Functionalization of Quinones with Boronic Acids

et al. 2011

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Direct functionalization of a variety of quinones with several boronic acids has been developed. This scalable reaction proceeds readily at room temperature in an open flask using inexpensive reagents: catalytic silver(I) nitrate in the presence of a persulfate co-oxidant. The scope with respect to quinones is broad with a variety of alkyl- and arylboronic acids undergoing efficient cross-coupling. The mechanism is presumed to proceed through a nucleophilic radical addition to the quinone with in situ reoxidation of the resulting dihydroquinone. This method has been applied to complex substrates including a steroid derivative and a farnesyl natural product.

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“…12 Our survey of standard Lewis bases for this process, such as 1,4-diazabicyclo[2.2.2]octane (DABCO) and triphenylphosphine, revealed there was poor and incomplete conversion when compared to the NHC catalyst generated from azolium catalyst A and sodium tert -butoxide. 13 Trans -1,2-bis(arylsulfonyl)ethylene has been used in organic synthesis, 14 but its preparation typically involves the use of vinyl chloride gas. 15 Alternatively, the straightforward preparation of 1,1-bis(phenylsulfonyl)ethylene involves paraformaldehyde, piperidine, and acid.…”

mentioning

confidence: 99%

N-heterocyclic carbene-catalyzed rearrangements of vinyl sulfones

2011

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N-heterocyclic carbenes catalyze the rearrangement of 1,1-bis(arylsulfonyl)ethylene to the corresponding trans-1,2-bis(phenylsulfonyl) under mild conditions. Tandem rearrangement/cycloadditions have been developed to capitalize on this new process and generate highly substituted isoxazolines and additional heterocyclic compounds. Preliminary mechanistic studies support a new conjugate addition/Umpolung process involving the ejection and subsequent unusual re-addition of a sulfinate ion.

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ModifiedB‐Alkylcatecholboranes as Radical Precursors

Cited by 35 publications

References 30 publications

Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands, meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

Strongly Luminous Tetranuclear Gold(I) Complexes Supported by Tetraphosphine Ligands, meso‐ or rac‐Bis[(diphenylphosphinomethyl)phenylphosphino]methane

Practical C−H Functionalization of Quinones with Boronic Acids

N-heterocyclic carbene-catalyzed rearrangements of vinyl sulfones

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