13235-07-9Relevant articles and documents
Synthesis of fluorenones by using Pd(ii)/Mg-La mixed oxide catalyst
Kishore, Ramineni,Shanthi Priya, Samudrala,Sudhakar, Medak,Venu, Boosa,Venugopal, Akula,Yadav, Jagjit,Kantam, Mannepalli Lakshmi
, p. 3363 - 3367 (2015)
Palladium(ii)/magnesium-lanthanum mixed oxide (Pd(ii)/Mg-La mixed oxide) catalyst was used in the dehydrogenative cyclization of benzophenones to afford fluorenones. This protocol represents a direct and facile approach to accessing a variety of fluorenone derivatives by means of C-H activation under heterogeneous conditions. The catalyst was recovered by centrifugation and used for three consecutive cycles with nearly consistent activity and selectivity.
Electronic Properties and Solid-State Packing of Isocyanofulvenes and Their Gold(I) Chloride Complexes
Schraff, Sandra,Trampert, Jens,Orthaber, Andreas,Pammer, Frank
, p. 17171 - 17183 (2020)
Two methods for the synthesis of isocyanofulvenes are reported, and a series of ligands of the type R2CH - NC (4a-g, R2 = a, 9-fluorenylidene; b, 9-(2,7-dioctyloxylfluorenylidene); c, 9-(3,6-dimethoxyfluorenylidene); d, 9-(3,6-dioctylfluorenylidene); e, 5-dibenzo[a,d]cycloheptenylidene; f, 9-thioxanthenylidene; and g, 2,5-dimethyl-3,4-diphenylcyclopentadienylidene) were prepared along with their gold(I) chloride complexes (R2CH - NC - AuCl, 5a-f). A comprehensive study of the properties of the precursors, free ligands, and gold(I) complexes is reported and complemented by DFT calculations. Solid-state structure of two complexes (5a and 5c) show extensive aurophilic interactions and π-πstacking of the ligands. The metal centers are not involved in optical transitions. However, metal coordination leads to a consistent bathochromic shift in the absorption spectra, which signifies the effective conjugation between the isocyano group and the π-systems of the ligands. Furthermore, an additional DFT study of carbonyl complexes of the type R2CH-NC-M(CO)5 (M = Cr, Mo, and W; R2CH - NC = 4a) indicates very effective metal-to-ligand charge transfer when isocyanopentafulvenes are used as ligands.
Expeditious Assembly of Fluorenones through Domino Reactions of Benzoyl Chlorides with Arylboronic Acids Catalyzed by ONO Pincer-like Palladium(II) Complexes
Vignesh, Arumugam,Kaminsky, Werner,Dharmaraj, Nallasamy
, p. 3207 - 3212 (2016)
A new set of palladium(II) complexes featuring ONO pincer-type ligands were synthesized and utilized as efficient homogeneous catalysts for the domino reactions of benzoyl chlorides with arylboronic acids to yield a library of fluorenones. The titled reaction proceeded smoothly in H2O/MeOH media at a low catalyst loading (0.1 mol %) under mild reaction conditions in an open flask, and the catalyst could be reused over six consecutive runs. To validate the currently developed methodology for industrial-level applications, a gram-scale synthesis was done. Advantageously, the present protocol does not require any external oxidant, additives, or phase-transfer agents.
Pd-catalyzed double C-H bond activation of diaryl ketones for the synthesis of fluorenones
Gandeepan, Parthasarathy,Hung, Chen-Hsun,Cheng, Chien-Hong
, p. 9379 - 9381 (2012)
An efficient synthesis of fluorenones from diaryl ketones by Pd-catalyzed oxidative cyclization is described. A possible mechanism involving a carbonyl group assisted ortho-C-H activation and cyclometalation followed by a second C-H activation to form a six-membered palladacycle and reductive elimination is proposed.
Tailoring Valence Tautomerism by Using Redox Potentials: Studies on Ferrocene-Based Triarylmethylium Dyes with Electron-Poor Fluorenylium and Thioxanthylium Acceptors
Casper, Larissa A.,Linseis, Michael,Demeshko, Serhiy,Azarkh, Mykhailo,Drescher, Malte,Winter, Rainer F.
, p. 10854 - 10868 (2021)
Three new electrochromic ferrocenyl triarylmethylium dyes with fluorenylium (1 a+, 1 b+) or thioxanthylium (1 c+) residues were selected in order to keep the intrinsic differences of redox potentials for ferrocene oxidation and triarylmethylium reduction small and to trigger valence tautomerism (VT). UV/Vis/NIR and quantitative EPR spectroscopy identified paramagnetic diradical isomers 1 a.+–1 c.+ alongside diamagnetic forms 1 a+–1 c+, which renders these complexes magnetochemical switches. The diradical forms 1 a.+–1 c.+ as well as the one-electron-reduced triarylmethyl forms of the complexes were found to dimerize in solution. For radical 1 a., dimerization occurs on the timescale of cyclic voltammetry; this allowed us to determine the kinetics and equilibrium constant for this process by digital simulation. M??bauer spectroscopy indicated that 1 a+ and 1 b+ retain VT even in the solid state. UV/Vis/NIR spectro-electrochemistry revealed the poly-electrochromic behaviour of these complexes by establishing the distinctly different electronic absorption profiles of the corresponding oxidized and reduced forms.
One-Pot Palladium(II)-Catalyzed Synthesis of Fluorenones via Decarboxylative Cyclization
Cai, Zhiqiang,Hou, Xu,Hou, Ling,Hu, Zhiquan,Zhang, Bo,Jin, Zhengsheng
, p. 395 - 398 (2016)
A one-pot palladium-catalyzed synthesis of fluoronones via decarboxylative cyclization is reported. This protocol offers good yields and tolerates a broad range of functional groups. Based on the extensive experimental data, we propose a plausible decarboxylative insertion mechanism.
Overhauser Dynamic Nuclear Polarization with Selectively Deuterated BDPA Radicals
Delage-Laurin, Léo,Golota, Natalie,Griffin, Robert G.,Mardini, Michael,Ouyang, Yifu,Palani, Ravi Shankar,Swager, Timothy M.,Tan, Kong Ooi
supporting information, p. 20281 - 20290 (2021/12/03)
The Overhauser effect (OE), commonly observed in NMR spectra of liquids and conducting solids, was recently discovered in insulating solids doped with the radical 1,3-bisdiphenylene-2-phenylallyl (BDPA). However, the mechanism of polarization transfer in OE-DNP in insulators is yet to be established, but hyperfine coupling of the radical to protons in BDPA has been proposed. In this paper we present a study that addresses the role of hyperfine couplings via the EPR and DNP measurements on some selectively deuterated BDPA radicals synthesized for this purpose. Newly developed synthetic routes enable selective deuteration at orthogonal positions or perdeuteration of the fluorene moieties with 2H incorporation of >93%. The fluorene moieties were subsequently used to synthesize two octadeuterated BDPA radicals, 1,3-[α,γ-d8]-BDPA and 1,3-[β,δ-d8]-BDPA, and a BDPA radical with perdeuterated fluorene moieties, 1,3-[α,β,γ,δ-d16]-BDPA. In contrast to the strong positive OE enhancement observed in degassed samples of fully protonated h21-BDPA (? ～+70), perdeuteration of the fluorenes results in a negative enhancement (? ～-13), while selective deuteration of α- and γ-positions (aiso ～5.4 MHz) in BDPA results in a weak negative OE enhancement (? ～-1). Furthermore, deuteration of β- and δ-positions (aiso ～1.2 MHz) results in a positive OE enhancement (? ～+36), albeit with a reduced magnitude relative to that observed in fully protonated BDPA. Our results clearly show the role of the hyperfine coupled α and γ1H spins in the BDPA radical in determining the dominance of the zero and double-quantum cross-relaxation pathways and the polarization-transfer mechanism to the bulk matrix.
Synthesis of fluorenone derivatives through Pd-catalyzed dehydrogenative cyclization
Li, Hu,Zhu, Ru-Yi,Shi, Wen-Juan,He, Ke-Han,Shi, Zhang-Jie
, p. 4850 - 4853,4 (2012/12/12)
Palladium-catalyzed dual C-H functionalization of benzophenones to form fluorenones by oxidative dehydrogenative cyclization is reported. This method provides a concise and effective route toward the synthesis of fluorenone derivatives, which shows outstanding functional group compatibility.
Photoinduced C-Br homolysis of 2-bromobenzophenones and Pschorr ring closure of 2-aroylaryl radicals to fluorenones
Moorthy, Jarugu Narasimha,Samanta, Subhas
, p. 9786 - 9789 (2008/03/17)
(Chemical Equation Presented) A variety of diversely substituted 2-aroylaryl radicals, generated by photoinduced homolysis of 2-bromoarylketones, is shown to undergo Pschorr cyclization to yield fluorenones in moderate to excellent yields. The photochemical results illustrate that the substituents in the two phenyl rings of the 2-bromobenzophenone skeleton exert a dramatic influence on the reactivity of the derived 2-aroylaryl radicals. The disubstitution by methoxy groups in the radical ring renders the aryl σ-radical highly electrophilic and unreactive for hydrogen abstraction and cyclization. On the other hand, the substituents in the non-radical ring that strongly stabilize the hydrofluorenyl π-radical, formed subsequent to the attack of the 2-aroylaryl radical on the non-radical ring, promote cyclization to furnish fluorenones in excellent isolated yields.
Synthesis of Substituted Fluorenones and Substituted 3',3'-Dichlorospiro and Their Reactivities
Chew, Warren,Hynes, Rosemary C.,Harpp, David N.
, p. 4398 - 4404 (2007/10/02)
Several novel 9-fluorenones were synthesized and were used as precursors in an attempt to prepare unique substituted 3',3'-dichlorospiro.Several of the thiiranes were unstable and desulfurized during their preparation (7a-d, 11, 12). 3',3'-Dichloro(2,5-dimethoxyspiro (7f) was prepared along with 2,2-dichloro-3,3-bis(4-methoxyphenyl)thiirane (16), and 3',3'-dichloro-10,11-dihydrospirocycloheptane-5,2'-thiirane> (17) all of which were stable at room temperature.A study of the reactivity of fluorenyl-substituted thiiranes and other related thiiranes showed that the extent of aromaticity of the substituents at the 3-position of the thiiranes influences their stabilities.
