4425-68-7

Upstream product

• 60-29-7 diethyl ether 
• 6630-65-5 9-chlorofluorene 
• 5152-68-1 benzhydryl sodium 
• 4709-68-6 9-benzhydrylidenefluorene 
• 1836-87-9 9-Benzylidene-9H-fluorene 
• 591-51-5 phenyllithium 
• 3531-83-7 fluorenylsodium 
• 776-74-9 Bromodiphenylmethane 
• 132869-70-6 3',3'-diphenyl-spiro[fluoren-9,2'-oxirane] 
• 118716-44-2 2-(biphenyl-2-yl)-1,1-diphenylethylene 
• 81113-46-4 C₂₉H₂₂O₂S₂ 
• 119-61-9 benzophenone 
• 19853-09-9 2-phenylbenzyl bromide 
• 830-72-8 9H-fluorene-9-thione 

Relevant academic research and scientific papers

Stable group 8 metal porphyrin mono- And bis(dialkylcarbene) complexes: Synthesis, characterization, and catalytic activity

Alkyl-substituted carbene (CHR or CR2, R = alkyl) complexes have been extensively studied for alkylcarbene (CHR) ligands coordinated with high-valent early transition metal ions (a.k.a. Schrock carbenes or alkylidenes), yet dialkylcarbene (CR2) complexes remain less developed with bis(dialkylcarbene) species being little (if at all) explored. Herein, several group 8 metal porphyrin dialkylcarbene complexes, including Fe- and Ru-mono(dialkylcarbene) complexes [M(Por)(Ad)] (1a,b, M = Fe, Por = porphyrinato dianion, Ad = 2-adamantylidene; 2a,b, M = Ru) and Os-bis(dialkylcarbene) complexes [Os(Por)(Ad)2] (3a-c), are synthesized and crystallographically characterized. Detailed investigations into their electronic structures reveal that these complexes are formally low-valent M(ii)-carbene in nature. These complexes display remarkable thermal stability and chemical inertness, which are rationalized by a synergistic effect of strong metal-carbene covalency, hyperconjugation, and a rigid diamondoid carbene skeleton. Various spectroscopic techniques and DFT calculations suggest that the dialkylcarbene Ad ligand is unique compared to other common carbene ligands as it acts as both a potent σ-donor and π-acceptor; its unique electronic and structural features, together with the steric effect of the porphyrin macrocycle, make its Fe porphyrin complex 1a an active and robust catalyst for intermolecular diarylcarbene transfer reactions including cyclopropanation (up to 90% yield) and X-H (X = S, N, O, C) insertion (up to 99% yield) reactions.

Ligand-Free Ru-Catalyzed Direct sp3 C-H Alkylation of Fluorene Using Alcohols

The sp3 C-H alkylation of 9H-fluorene using alcohol and a Ru catalyst via the borrowing hydrogen concept has been described. This reaction was catalyzed by the [Ru(p-cymene)Cl2]2 complex (3 mol %) and exhibited a broad reaction scope with different alcohols, allowing primary and secondary alcohols to be employed as nonhazardous and greener alkylating agents with the formation of environmentally benign water as a byproduct. A variety of 9H-fluorene underwent selective and exclusive mono-C9-alkylation with primary alcohols in good to excellent isolated yield (26 examples, 50-92% yield), whereas this reaction with secondary alcohols in the absence of any external oxidants furnished the tetrasubstituted alkene as the major product. Furthermore, a base-mediated C-H hydroxylation of the synthesized 9H-fluorene derivatives afforded 9H-hydroxy-functionalized quaternary fluorene derivatives in excellent yield.

Vanadium Pyridonate Catalysts: Isolation of Intermediates in the Reductive Coupling of Alcohols

The reductive coupling of alcohols using vanadium pyridonate catalysts is reported. This attractive approach for C(sp3)-C(sp3) bond formation uses an oxophilic, earth-abundant metal for a catalytic deoxygenation reaction. Several pyridonate complexes of vanadium were synthesized, giving insight into the coordination chemistry of this understudied class of compounds. Isolated intermediates provide experimental mechanistic evidence that complements reported computational mechanistic proposals for the reductive coupling of alcohols. In contrast to previous mononuclear vanadium(V)/vanadium(III)/vanadium(IV) cycles, this pyridonate catalyst system is proposed to proceed by a vanadium(III)/vanadium(IV) cycle involving bimetallic intermediates.

Mechanistic Features of the Oxidation-Reductive Coupling of Alcohols Catalyzed by Oxo-Vanadium Complexes

The oxo-vanadium-catalyzed redox disproportionation of activated alcohols (oxidation-reductive coupling, Ox-RC) produces carbonyl compounds and hydrocarbon dimers. A mechanistic study of this novel reaction is reported herein. Following our initial disclosure, new findings include the following: (1) The [(salimin)VO2]--catalyzed Ox-RC of Ph2CHOH in the presence of fluorene affords the products of H-atom abstraction and all possible hydrocarbon dimers. (2) Electronic substituent effects on the relative rates of Ox-RC with respect to 4-X-BnOH reactants and Bu4N[(Y-salimin)VO2] catalysts (1a-c) reveal (a) a correlation of the oxidation rate of X-BnOH reactants with the radical σ parameter and (b) correlation of the oxidation rate for (Y-salimin)VO2- with the standard Hammett σ parameter. (3) The ease of electrochemical reduction of 1a-c is Y = NO2 > OMe > H. (4) Ambient 1H NMR studies of the interaction of 1 with alcohols suggest only a weak equilibrium association. (5) Density functional theory computational modeling of the Ox-RC reaction supports a ping-pong-type catalytic pathway, beginning with alcohol oxidation by (salimin)VO2-, preferably by stepwise-H-atom transfer from the alcohol to 1, affording the carbonyl product and the reduced (salimin)V(III)(OH)2-. The reduction half-reaction likely begins with condensation of the latter species with R2CHOH to give the alkoxide complex (salimin)V(OR)OH- homolysis of the R···OV(III)(salimin) bond affords (salimin)V(IV)OH(O)- and the R-radical; the latter dimerizes and the former can disproportionate via H-transfer to reform catalyst (salimin)VO2- (1) and (salimin)V(OH)2-.

Aldehyde/ketone-catalyzed highly selective synthesis of 9-monoalkylated fluorenes by dehydrative C-alkylation with primary and secondary alcohols

By using aldehydes or ketones as the catalyst and screening CsOH out as the more effective base than KOH in many instances, an efficient 9-C-alkylation of fluorenes with alcohols was achieved to provide a green and practical method for general synthesis of the useful 9-monoalkylated fluorenes in high selectivities. This new method tolerates a wide range of substrates including activated and unactivated primary and secondary alcohols, thus solving the issues remaining in the field and largely broadening the diversity of the 9-monoalkylated fluorenes. Consequently, fine-tuning of the alkylated fluorenes was made possible to provide specific fluorene monomers for function-oriented polyfluorenes. Preliminary mechanistic studies revealed that the external carbonyl compounds can be quantitatively regenerated and recovered in the reaction cycle.

Oxo-rhenium catalyzed reductive coupling and deoxygenation of alcohols

Representative benzylic, allylic and α-keto alcohols are deoxygenated to alkanes and/or reductively coupled to alkane dimers by reaction with PPh3 catalyzed by (PPh3)2ReIO2 (1). The newly discovered catalytic reductive coupling reaction is a rare C-C bond-forming transformation of alcohols.

Influence of Solvent and Cation on the Properties of Oxygen-containing Organic Anions. Part 4. Mechanism and Reactivity of Tetraaryloxirane Cleavage with Alkali Metals

Six tetraaryloxiranes 1a-f (Scheme 4) were reduced (Schemes 1-3) with alkali metals (M = Li, Na, K, Cs) in eight polar aprotic solvents under an inert atmosphere.The organometallic solutions thus obtained were hydrolysed and the reaction products analysed.Similar experiments were carried out where the same solutions were quenched with D2O or MeI.In some cases the same solutions were studied by NMR and ESR spectroscopy before quenching.A stepwise reduction mechanism was established where the transfer of a first electron produces CO-bond scission in the oxirane ring, yielding a short-lived radical anion 4 or 5 (Scheme 1), i. e., a tetraalkyl-β-oxidoethyl radical.This intermediate can either eliminate oxygen as metal oxide (MO) to produce a tetraarylethylene 24 (Scheme 2) or be further reduced to a dianion 8 or 9 (Scheme 1).This anion yields, upon hydrolysis, low yields,if any, of the corresponding tetraphenylethanol 15 or 16 (Z = H).The larger proportion of the dianion, after the first protonation step, yielding anion 11 or 22, undergoes CC-bond scission which leads eventually to the corresponding ketone and diarylmethane 19 + 20 or 21 + 23 (Z = H) (Scheme 2).Other possible pathways were excluded through experiments where other possible intermediates were generated.These led to different end products.A triparametric linear correlation as a function of solvent parameters ETN and DN, as well as the cationic radius, was established for the influence of the nature of the solvent and counter-ion on the ratio between the rates of formation of products stemming from metal oxide (MO) elimination by the ring-opened radical anion 4 or 5 (Schemes 1 and 2) and rates of formation of products stemming from further reduction of the same radical anion to the dianion 8 or 9, thus confirming the mechanism established.

Carbon-Skeletal Anionic Rearrangements and the ?-Orbital Overlap Constraint: The Question of Nucleophilic Attack versus Electron Transfer

In order to evaluate the geometrical requirements and the actual electronic nature of apparent anionic rearrangements of metalated aromatic hydrocarbons, amines, and ethers, cyclic structural types of such anions were generated as lithium salts by proton abstraction from C-H bonds by RLi or by C-Cl bond cleavage by Li.The cyclic systems examined were anions of 9,9-dimethyl-, 9-methyl-9-benzyl-, and 9-benzyl-9-phenylfluorenes; 9-methyl-9-phenyl-, 9,9-diphenyl-, and 9,9-(2,2'-biphenylene)-9,10-dihydrophenanthrenes; 5-methyl- and 5-phenyl-5,6-dihydrophenathridines;and 9H-dibenzopyran.The anions generated from 9-methyl-9-benzylfluorene, 9-benzyl-9-phenylfluorene, 5-methyl-5,6-dihydrophenanthridine, and 9H-dibenzopyran, as well as 9-methyl-9-(lithiomethyl)fluorene, did not undergo skeletal rearrangement when heated between 40 and 120 deg C for protracted periods.However, the anions derived from the 9-methyl-9-phenyl-, 9,9-diphenyl-, and 9,9-(2,2'-biphenylene)-9,10-dihydrophenanthrenes did undergo rearrangement with a shift of the 9-aryl group.With the anion of 5-phenyl-5,6-dihydrophenanthridine, some shift of the 5-phenyl was observed, but the principal rearrangement was ring contraction with the formation of N-phenyl-9-fluorenylamine.By noting which anions underwent skeletal rearrangement and which competing migrating groups in a given anion underwent a shift preferentially, we have formulated an appropriate geometrical view of the transition states involved.Furthermore, by generating the 2,2,2-triphenylethyl anion (as its lithium salt) from (a) 2-chloro-1,1,1-triphenylethane and Li, (b) 2-bromo-1,1,1-triphenylethane and n-BuLi, and (c) bis(2,2,2-triphenylethyl)mercury and n-BuLi, we attempted to learn whether such shifts were truly nucleophilic or whether SET processes were involved.Evidence for SET processes was obtained for the generation of (2,2,2-triphenylethyl)lithium by method a, but no ESR or CIDNP evidence for radical intermediates was observable when (2,2,2-triphenylethyl)lithium was produced by method c.

THE REACTION OF DIAZOACETIC ESTER WITH THIOBENZOPHENONE

Methyl diazoacetate reacts with two equivalents of thiobenzophenone to furnish two isomeric 1,3-dithiolanes and nitrogen; the intermediate thiocarbonyl ylide is intercepted by 1,3-dipolar cycloaddition or undergoes electrocyclic ring closure.