Anomaly in palladium-catalyzed phenylethynylation of 2,2'-dihalobiphenyls: formation of alkylidenefluorenes

The reaction of tributylphosphane with a 7‐(2′‐formyl‐2‐biphenylyl)phosphanorbornadiene P‐W(CO)5 complex leads to the 5‐phosphaphenanthrene P‐W(CO)5 complex via an intramolecular phospha‐Wittig condensation. This complex is stable enough for detection by 31P NMR spectroscopy but cannot be isolated due to its high reactivity. It is trapped by addition of MeOH or cycloaddition with 2,3‐dimethylbutadiene or a nitrileimine. The adducts were characterized by X‐ray crystal structure analysis.

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“…It was prepared from 2,2Ј-dibromobiphenyl [5] in three steps and 81 % overall yield as shown in Equation (1).…”

Section: Resultsmentioning

confidence: 99%

A Phospha‐Wittig Route to 5‐Phosphaphenanthrene

et al. 2011

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“…Commercial reagents were used without prior purification. 2,2'-dibromobiphenyl was synthesized using a known procedure 27 . Flash column chromatography was performed using Silicycle silica 60 (230-400 mesh).…”

Section: Methodsmentioning

confidence: 99%

Radical chain reactions involving 9-alkyl-9-borafluorenes

Gorokhovik¹,

Rieder²,

Povie³

et al. 2014

Arkivoc

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The preparation of 9-alkyl-9-borafluorenes and their use as radical precursors in chain reactions were investigated. These organoboranes were found to be excellent precursors of primary and secondary alkyl radicals. Reactions were readily initiated by traces of oxygen and efficient processes involving sulfonyl-based radical traps were discovered. Due to the very high reactivity of the intermediate 9-H and 9-alkyl-9-borafluorenes, problems of reproducibility were identified.

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“…While 2-(phenylethynyl)napthalene forms slowly the two expected ketones in equal amounts (Table 1, entry 6), the more hindered 1-(phenylethynyl)naphthalene does not react at all under the same conditions. Likewise, 9-(phenylethynyl)-phenanthrene [16] and 1,2-bis(phenylethynyl)benzene [17] proved inactive.…”

Section: Dependence On the Substratementioning

confidence: 97%

Further studies on hydration of alkynes by the PtCl4–CO catalyst

Israelsohn

Vollhardt

Blum

2002

Journal of Molecular Catalysis A: Chemical

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Dedicated to Professor Myron Rosenblum on the occasion of his 75 th birthday in recognition of his outstanding contribution to chemistry AbstractUnder CO atmosphere, between 80 and 120˚C, a glyme solution of PtCl 4 forms a carbonyl compound that promotes hydration of internal as well as terminal alkynes to give aldehyde-free ketones. The catalytic process depends strongly on the electronic and steric nature of the substrates. Part of the carbonyl functions of the catalyst can be replaced by phosphine ligands. Chiral DIOP reacts with the PtCl 4 -CO compound to give a catalyst that promotes partial kinetic resolution of a racemic alkyne. Replacement of part of the CO by polystyrene-bound diphenylphosphine enables to attach the catalyst to the polymeric support. Upon entrapment of the platinum compound in a silica sol-gel matrix, it reacts as a partially recyclable catalyst. A reformulated mechanism for the PdCl 4 -CO catalyzed hydration is suggested on the basis of the present study.

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Anomaly in palladium-catalyzed phenylethynylation of 2,2'-dihalobiphenyls: formation of alkylidenefluorenes

Cited by 63 publications

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A Phospha‐Wittig Route to 5‐Phosphaphenanthrene

A Phospha‐Wittig Route to 5‐Phosphaphenanthrene

Radical chain reactions involving 9-alkyl-9-borafluorenes

Further studies on hydration of alkynes by the PtCl4–CO catalyst

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