173276-82-9Relevant academic research and scientific papers
Structural modifications of nile red carbon monoxide fluorescent probe: Sensing mechanism and applications
Klán, Petr,Madea, Dominik,Martínek, Marek,Muchová, Lucie,Váňa, Ji?í,Vítek, Libor
, p. 3473 - 3489 (2020/03/25)
Carbon monoxide (CO) is a cell-signaling molecule (gasotransmitter) produced endogenously by oxidative catabolism of heme, and the understanding of its spatial and temporal sensing at the cellular level is still an open challenge. Synthesis, optical properties, and study of the sensing mechanism of Nile red Pd-based CO chemosensors, structurally modified by core and bridge substituents, in methanol and aqueous solutions are reported in this work. The sensing fluorescence "off-on" response of palladacycle-based sensors possessing low-background fluorescence arises from their reaction with CO to release the corresponding highly fluorescent Nile red derivatives in the final step. Our mechanistic study showed that electron-withdrawing and electron-donating core substituents affect the rate-determining step of the reaction. More importantly, the substituents were found to have a substantial effect on the Nile red sensor fluorescence quantum yields, hereby defining the sensing detection limit. The highest overall fluorescence and sensing rate enhancements were found for a 2-hydroxy palladacycle derivative, which was used in subsequent biological studies on mouse hepatoma cells as it easily crosses the cell membrane and qualitatively traces the localization of CO within the intracellular compartment with the linear quantitative response to increasing CO concentrations.
Aryne cycloaddition reactions of benzodioxasilines as aryne precursors generated by catalytic reductive ortho-C[sbnd]H silylation of phenols with traceless acetal directing groups
Asgari, Parham,Dakarapu, Udaya Sree,Nguyen, Hiep H.,Jeon, Junha
, p. 4052 - 4061 (2017/06/29)
Diversely substituted arylsilyl triflates, as aryne precursors for aryne cycloaddition reactions, were accessed from benzodioxasilines. Catalytic reductive C[sbnd]H ortho-silylation of phenols with traceless acetal directing groups was exploited to prepare benzodioxasilines. Sequential addition of MeLi and then trifluoromethanesulfonic anhydride to benzodioxasilines provided arylsilyl triflates in a single pot. Notably, this approach was successfully utilized to prepare sterically hindered 1,2,3-trisubstituted arylsilyl triflates, which ultimately underwent fluoride-mediated aryne cycloaddition.
A Selective C?H Deprotonation Strategy to Access Functionalized Arynes by Using Hypervalent Iodine
Sundalam, Sunil K.,Nilova, Aleksandra,Seidl, Thomas L.,Stuart, David R.
, p. 8431 - 8434 (2016/07/19)
Described here is an efficient method to access highly functionalized arynes from unsymmetrical aryl(mesityl)iodonium tosylate salts. The iodonium salts are prepared in a single pot from either commercially available aryl iodides or arylboronic acids. The
Catalytic Reductive ortho-C-H Silylation of Phenols with Traceless, Versatile Acetal Directing Groups and Synthetic Applications of Dioxasilines
Hua, Yuanda,Asgari, Parham,Avullala, Thirupataiah,Jeon, Junha
, p. 7982 - 7991 (2016/07/07)
A new, highly selective, bond functionalization strategy, achieved via relay of two transition metal catalysts and the use of traceless acetal directing groups, has been employed to provide facile formation of C-Si bonds and concomitant functionalization of a silicon group in a single vessel. Specifically, this approach involves the relay of Ir-catalyzed hydrosilylation of inexpensive and readily available phenyl acetates, exploiting disubstituted silyl synthons to afford silyl acetals and Rh-catalyzed ortho-C-H silylation to provide dioxasilines. A subsequent nucleophilic addition to silicon removes the acetal directing groups and directly provides unmasked phenol products and, thus, useful functional groups at silicon achieved in a single vessel. This traceless acetal directing group strategy for catalytic ortho-C-H silylation of phenols was also successfully applied to preparation of multisubstituted arenes. Remarkably, a new formal α-chloroacetyl directing group has been developed that allows catalytic reductive C-H silylation of sterically hindered phenols. In particular, this new method permits access to highly versatile and nicely differentiated 1,2,3-trisubstituted arenes that are difficult to access by other catalytic routes. In addition, the resulting dioxasilines can serve as chromatographically stable halosilane equivalents, which allow not only removal of acetal directing groups but also introduce useful functional groups leading to silicon-bridged biaryls. We demonstrated that this catalytic C-H bond silylation strategy has powerful synthetic potential by creating direct applications of dioxasilines to other important transformations, examples of which include aryne chemistry, Au-catalyzed direct arylation, sequential orthogonal cross-couplings, and late-stage silylation of phenolic bioactive molecules and BINOL scaffolds.
Synthesis of monofluorinated 1-(naphthalen-1-yl)piperazines
Repine, Joseph T.,Johnson, Douglas S.,White, Andrew D.,Favor, David A.,Stier, Michael A.,Yip, Judy,Rankin, Trent,Ding, Qizhu,Maiti, Samarendra N.
, p. 5539 - 5541 (2008/02/13)
A series of regioisomerically monofluorinated 1-(naphthalen-1-yl)piperazines is described.
Synthesis of benzonorbornadienes: Regioselective benzyne formation
Caster,Keck,Walls
, p. 2932 - 2936 (2007/10/03)
This report details the synthesis of several benzonorbornadienes by Diels-Alder cycloaddition of cyclopentadiene derivatives with substituted benzyne intermediates, which were generated by low-temperature metal-halogen exchange of halobenzenes. General conditions were developed, allowing synthesis of most benzonorbornadienes described herein at the multigram scale with isolated yields approaching 90% in some cases. Cycloaddition of the benzyne produced by substitution of a chlorodifluorobenzene for a bromodifluorobenzene in the metal-halogen exchange reaction unexpectedly gave a different benzonorbornadiene. The benzyne, which resulted by a deprotonation pathway rather than by metal-halogen exchange, formed in a highly regioselective elimination step.
The lithiation of fluorinated benzenes and its dependence on solvent and temperature
Coe, Paul Leslie,Waring, Anthony John,Yarwood, Thomas David
, p. 2729 - 2738 (2007/10/02)
The formation of lithio derivatives from fluorinated benzenes and fluorinated bromobenzenes has been studied.The bases used were lithium diisopropylamide (LDA) in THF-hexane, butyllithium in diethyl ether-hexane and butyllithium in THF-hexane.The lithiated intermediates have been trapped using acetone, to form fluorinated 2-arylpropan-2-ols, or have been warmed to produce benzynes which have trapped by furan in Diels-Alder additions.The use of LDA allows clean removal of the most acidic proton in the aromatic ring: butyllithium in ether-hexane brings about clean bromine-lithium exchange.In constrast, the use of butyllithium in THF-hexane at -78 deg C results in autometallation and the formation of more complex product mixtures.For the formation of the benzynes involved in the Diels-Alder reactions it is necessary to warm the reaction mixtures.When ether-hexane is used as solvent the reactions remain fairly clean, but when THF is added the increasing autometallation again results in more complex reaction mixtures.
