1572-46-9Relevant articles and documents
THE STOICHIOMETRIC HYDROGENATION OF 9-METHYLIDENEFLUORENE AND RELATED COMPOUNDS WITH HYDRIDOCOBALT TETRACARBONYL
Nalesnik, Theodore E.,Orchin, Milton
, p. 265 - 270 (1980)
9-Methylidenefluorene (IIa) reacts rapidly with HCo(CO)4 at -67 deg C to give a quantitative yield of 9-methylfluorene (IIIa); k2=(13.4 +/- 0.5)*10-2 l mol-1 s-1.Although the internal olefin, 9-ethylidenefluorene (IIb) reacts more slowly than IIa, it is hydrogenated about 2.5 times as fast as the terminal olefin, 1,1-diphenylethylene (I).Measurement of the rate of the reaction of IIb with DCo(CO)4 and comparison with HCo(CO)4 shows a very large inverse isotope effect kH/kD of 0.43.
Modular Tandem Mizoroki-Heck/Reductive Heck Reactions to Construct Fluorenes from Cyclic Diaryliodoniums
Peng, Xiaopeng,Yang, Yang,Luo, Bingling,Wen, Shijun,Huang, Peng
, p. 222 - 226 (2020/12/01)
Starting from cyclic diaryliodoniums and terminal alkenes, a diverse set of fluorenes is conveniently constructed. The reactions catalyzed by palladium undergo one conventional Mizoroki-Heck reaction and one reductive Heck reaction. The scope of alkenes is general, leading to 29 fluorenes which would expand the structural diversity of fluorene reservoir. (Figure presented.).
Alumina-Mediated π-Activation of Alkynes
Akhmetov, Vladimir,Amsharov, Konstantin,Feofanov, Mikhail,Sharapa, Dmitry I.
supporting information, p. 15420 - 15426 (2021/09/30)
The ability to induce powerful atom-economic transformation of alkynes is the key feature of carbophilic π-Lewis acids such as gold- and platinum-based catalysts. The unique catalytic activity of these compounds in electrophilic activations of alkynes is explained through relativistic effects, enabling efficient orbital overlapping with π-systems. For this reason, it is believed that noble metals are indispensable components in the catalysis of such reactions. In this study, we report that thermally activated γ-Al2O3activates enynes, diynes, and arene-ynes in a manner enabling reactions that were typically assigned to the softest π-Lewis acids, while some were known to be triggered exclusively by gold catalysts. We demonstrate the scope of these transformations and suggest a qualitative explanation of this phenomenon based on the Dewar-Chatt-Duncanson model confirmed by density functional theory calculations.
Ligand-Free Ru-Catalyzed Direct sp3 C-H Alkylation of Fluorene Using Alcohols
Shaikh, Moseen A.,Agalave, Sandip G.,Ubale, Akash S.,Gnanaprakasam, Boopathy
, p. 2277 - 2290 (2020/02/04)
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.
Manganese-Catalyzed Synthesis of Quaternary Peroxides: Application in Catalytic Deperoxidation and Rearrangement Reactions
Chaudhari, Moreshwar B.,Gnanaprakasam, Boopathy,Shaikh, Moseen A.,Ubale, Akash S.
, p. 10488 - 10503 (2020/09/23)
Highly efficient, selective, and direct C-H peroxidation of 9-substituted fluorenes has been achieved using a Mn-2,2′-bipyridine catalyst via radical-radical cross-coupling. Moreover, this method effectively promotes the vicinal bisperoxidation of sterically hindered various substituted arylidene-9H-fluorene/arylideneindolin-2-one derivatives to afford highly substituted bisperoxides with high selectivity over the oxidative cleavage of Ca C bond that usually forms the ketone of an aldehyde. Furthermore, a new approach for the synthesis of (Z)-6-benzylidene-6H-benzo[c]chromene has been achieved via an acid-catalyzed skeletal rearrangement of these peroxides. For the first time, unlike O-O bond cleavage, reductive C-O bond cleavage in peroxides using the Pd catalyst and H2 is described, which enables the reversible reaction to afford exclusively deperoxidized products. A detailed mechanism for peroxidation, molecular rearrangement, and deperoxidation has been proposed with preliminary experimental evidences.
T -BuOK-catalysed alkylation of fluorene with alcohols: A highly green route to 9-monoalkylfluorene derivatives
Fan, Jiang-Tao,Fan, Xin-Heng,Gao, Cai-Yan,Wang, Zhenpeng,Yang, Lian-Ming
, p. 35913 - 35916 (2019/11/16)
A simple, mild and efficient protocol was developed for the alkylation of fluorene with alcohols in the presence of t-BuOK as catalyst, affording the desired 9-monoalkylfluorenes with near quantitative yields in most cases.
Nickel-catalyzed synthesis of 9-monoalkylated fluorenes from 9-fluorenone hydrazone and alcohols
Fan, Jiang-Tao,Fan, Xin-Heng,Chen, Yong-Jie,Gao, Cai-Yan,Yang, Lian-Ming
, p. 2895 - 2902 (2019/08/12)
A practical protocol was disclosed for the nickel-catalyzed C-alkylation of 9-fluorenone hydrazone with alcohols using t-BuOK as the base, and 9-monoalkylated fluorene derivatives were obtained in good yields under the benign conditions.
Au-Catalyzed Biaryl Coupling to Generate 5- To 9-Membered Rings: Turnover-Limiting Reductive Elimination versus ?-Complexation
Ball, Liam T.,Corrie, Tom J. A.,Lloyd-Jones, Guy C.,Russell, Christopher A.
, p. 245 - 254 (2021/09/04)
The intramolecular gold-catalyzed arylation of arenes by aryl-trimethylsilanes has been investigated from both mechanistic and preparative aspects. The reaction generates 5- to 9-membered rings, and of the 44 examples studied, 10 include a heteroatom (N, O). Tethering of the arene to the arylsilane provides not only a tool to probe the impact of the conformational flexibility of Ar-Au-Ar intermediates, via systematic modulation of the length of aryl-aryl linkage, but also the ability to arylate neutral and electron-poor arenes - substrates that do not react at all in the intermolecular process. Rendering the arylation intramolecular also results in phenomenologically simpler reaction kinetics, and overall these features have facilitated a detailed study of linear free energy relationships, kinetic isotope effects, and the first quantitative experimental data on the effects of aryl electron demand and conformational freedom on the rate of reductive elimination from diaryl-gold(III) species. The turnover-limiting step for the formation of a series of fluorene derivatives is sensitive to the reactivity of the arene and changes from reductive elimination to ?-complexation for arenes bearing strongly electron-withdrawing substituents (σ > 0.43). Reductive elimination is accelerated by electron-donating substituents (ρ = -2.0) on one or both rings, with the individual σ-values being additive in nature. Longer and more flexible tethers between the two aryl rings result in faster reductive elimination from Ar-Au(X)-Ar and lead to the ?-complexation of the arene by Ar-AuX2 becoming the turnover-limiting step.
Aldehyde/ketone-catalyzed highly selective synthesis of 9-monoalkylated fluorenes by dehydrative C-alkylation with primary and secondary alcohols
Chen, Jianhui,Li, Yang,Li, Shuangyan,Liu, Jianping,Zheng, Fei,Zhang, Zhengping,Xu, Qing
, p. 623 - 628 (2017/08/17)
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.
Au-catalyzed biaryl coupling to generate 5- to 9-membered rings: Turnover-limiting reductive elimination versus π-complexation
Corrie, Tom J. A.,Ball, Liam T.,Russell, Christopher A.,Lloyd-Jones, Guy C.
supporting information, p. 245 - 254 (2017/05/29)
The intramolecular gold-catalyzed arylation of arenes by aryl-trimethylsilanes has been investigated from both mechanistic and preparative aspects. The reaction generates 5- to 9-membered rings, and of the 44 examples studied, 10 include a heteroatom (N, O). Tethering of the arene to the arylsilane provides not only a tool to probe the impact of the conformational flexibility of Ar-Au-Ar intermediates, via systematic modulation of the length of aryl-aryl linkage, but also the ability to arylate neutral and electron-poor arenes-substrates that do not react at all in the intermolecular process. Rendering the arylation intramolecular also results in phenomenologically simpler reaction kinetics, and overall these features have facilitated a detailed study of linear free energy relationships, kinetic isotope effects, and the first quantitative experimental data on the effects of aryl electron demand and conformational freedom on the rate of reductive elimination from diaryl-gold(III) species. The turnover-limiting step for the formation of a series of fluorene derivatives is sensitive to the reactivity of the arene and changes from reductive elimination to π-complexation for arenes bearing strongly electron-withdrawing substituents (σ > 0.43). Reductive elimination is accelerated by electron-donating substituents (ρ = -2.0) on one or both rings, with the individual σ-values being additive in nature. Longer and more flexible tethers between the two aryl rings result in faster reductive elimination from Ar-Au(X)-Ar and lead to the π-complexation of the arene by Ar-AuX2 becoming the turnover-limiting step.
