- Build-up of double carbohelicenes using nitroarenes: Dual role of the nitro functionality as an activating and leaving group
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The construction of double carbohelicenes is highly fascinating yet challenging work. Disclosed herein is a streamlined and simplified synthetic route to double carbohelicenes starting from nitroarenes through sequential nitro-activated ortho-C-H arylation, denitrative alkenylation and intramolecular cyclodehydrogenation. In this synthetic strategy, the nitro group plays a dual role namely as a leaving group for the denitrative alkenylation and as an activating group for ortho-C-H arylation, which is distinct from those of aryl halides in a conventional coupling reaction. In this work, the palladium-catalyzed Heck-type alkenylation of nitroarenes has been presented, in which the conventionally inert Ar-NO2 bond is cleaved. This work provides a novel synthetic strategy for polycyclic aromatic hydrocarbons (PAHs). This journal is
- Su, Rongchuan,Yang, Yudong,You, Jingsong,Zhou, Fujian,Zhou, Fulin
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p. 7424 - 7428
(2020/09/09)
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- Palladium-catalyzed annulation of 1,2-diborylalkenes and -arenes with 1-bromo-2-[(Z)-2-bromoethenyl]arenes: A modular approach to multisubstituted naphthalenes and fused phenanthrenes
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(Z)-1,2-Diaryl-1,2-bis(pinacolatoboryl)ethenes underwent double-cross-coupling reactions with 1-bromo-2-[(Z)-2-bromoethenyl]arenes in the presence of [Pd(PPh3)4] as a catalyst and 3 M aqueous Cs2CO3 as a base in THF at 80 °C. The double-coupling reaction gave multisubstituted naphthalenes in good to high yields. Annulation of 1,2-bis(pinacolatoboryl)arenes with bromo(bromoethenyl)arenes in the presence of a catalyst system that consisted of [Pd2(dba)3] (dba=dibenzylideneacetone) and 2-dicyclohexylphosphino-2′,6′- dimethoxybiphenyl (SPhos) under the same conditions produced fused phenanthrenes in good to high yields. The first annulation coupling occurred regiospecifically at the bromoethenyl moiety. This procedure is applicable to the facile synthesis of polysubstituted anthracenes, benzothiophenes, and dibenzoanthracenes through a double annulation pathway by using the corresponding dibromobis[(Z)-2-bromoethenyl]benzenes as diboryl coupling partners. Copyright
- Shimizu, Masaki,Tomioka, Yosuke,Nagao, Ikuhiro,Kadowaki, Tsugumi,Hiyama, Tamejiro
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experimental part
p. 1644 - 1651
(2012/09/08)
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- Accelerated Heck reaction using ortho-palladated complex in a nonaqueous ionic liquid with controlled microwave heating
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The activity of {Pd[C6H2(CH2CH 2NH2)-(OMe)2,3,4] (μ-Br)}2 complex was investigated in the Heck-Mizoroki C-C cross-coupling reaction under conventional heating and microwave irradiation conditions in molten salt tetrabutylammonium bromide as the solvent and promoter at 130 °C. This complex in these conditions is an active and efficient catalyst for the Heck reaction of aryl iodides, bromides and even chlorides, and also arenesulfonyl chlorides. Copyright
- Hajipour, Abdol R.,Rafiee, Fatemeh
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experimental part
p. 542 - 551
(2012/04/04)
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- Heck coupling reaction using monomeric ortho-palladated complex of 4-methoxy- benzoylmethylenetriphenylphosphorane under microwave irradiation
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The activity of [Pd(C6H4CH2 NH 2-κ2-C-N)PPh3MOBPPY]OTf complex, A (MOBPPY = 4-methoxybenzoylmethylenetriphenyl- phosphoraneylide), was investigated in the Heck-Mizoroki C-C cross-coupling reaction under conventional heating and microwave irradiation conditions. The complex is an active and efficient catalyst for the Heck reaction of aryl halides. The yields were excellent using a catalytic amount of [Pd(C6H4CH 2 NH2-κ2-C-N)PPh3MOBPPY]OTf complex in N-methyl-2-pyrrolidinone (NMP) at 130 °C and 600 W. In comparison to conventional heating conditions, the reactions under microwave irradiation gave higher yields in shorter reaction times. Copyright
- Hajipour, Abdol R.,Karami, Kazem,Tavakoli, Ghazal
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experimental part
p. 798 - 804
(2011/06/20)
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- Application of dimeric orthopalladate complex of homoveratrylamine as an efficient catalyst in the Heck cross-coupling reaction
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The [Pd{C6H2(CH2CH2NH2)-(OMe)2,3,4} (μ-Br)]2 complex of homoveratrylamine was synthesized and its application in the Heck coupling reaction was studied. This complex had been demonstrated to be active and efficient catalyst for the Heck reaction of aryl iodides, bromides and even chlorides. The cross-coupled products were produced in excellent yields in a short reaction time using catalytic amounts of [Pd{C6H2(CH2CH2NH2)-(OMe)2,3,4} (μ-Br)]2 complex in N-methyl-2-pyrrolidinone (NMP at 130 °C).
- Hajipour, Abdol R.,Karami, Kazem,Pirisedigh, Azadeh,Ruoho, Arnold E.
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experimental part
p. 2548 - 2554
(2009/12/24)
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- A novel bis-Lactonisation of naphtho- and phenanthro-1,2-dioxines with malonate nucleophiles
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Malonate nucleophiles add in a conjugate fashion to substituted naphtho- and phenanthro-1,2-dioxines to furnish functionalised bis-lactones in high yield and with high de. The basicity of the malonate nucleophile is sufficiently mild to rearrange the 1,2-dioxines to yield the transient cis-δhydroxy enone species with no further Kornblum-DeLaMare rearrangement. The cis-δhydroxy enones readily undergo conjugate addition by malonate nucleophiles in a highly diastereoselective fashion. An intramolecular domino cyclisation then ensues yielding the observed bis-lactones. The relative configuration of the bis-lactone series was established by 1- and 2-D 1H, 13C NMR techniques and further confirmed by single crystal X-ray analysis.
- Greatrex, Ben,Jevric, Martyn,Kimber, Marc C.,Krivickas, Sara J.,Taylor, Dennis K.,Tiekink, Edward R. T.
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p. 668 - 672
(2007/10/03)
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- Role of Charge-Transfer Interactions in Photoreactions. 6. Photoinduced Electron Transfer and Trans -> Cis Isomerization for Styrylphenanthrene-Amine Systems in Acetonitrile
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The decay pathways of the lowest excited singlet state (S1) of trans-n-styrylphenanthrenes (n-StPh, with the location on phenanthrene n = 1, 2, 3, 4, and 9) were studied in acetonitrile at room temperature.Fluorescence lifetimes (τF)
- Aloisi, Gian Gaetano,Elisei, Fausto,Goerner, Helmut
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p. 4225 - 4231
(2007/10/02)
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- Photochemical and Photophysical Behaviour of 9-Styrylphenanthrene and its Aza-Analogues
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The photochemical and photophysical behaviour of 9-styrylphenanthrene and its pyridyl analogues, the 9-phenanthryl, n-pyridyl-ethylenes (n = 2,3,4), were studied in n-hexane and acetonitrile-water.Fluorescence spectra, quantum yields and lifetimes and trans --> cis photoisomerization quantum yields were determined for the trans isomers.The cis --> trans photoisomerization and dehydrophotocyclization quantum yields were measured for the cis isomers.The photocyclization products were isolated and characterized.The results obtained give a general picture of the competition among the various deactivating processes in these compounds.Mechanistic information is obtained also by comparison with what was found for other stilbene - like molecules. . - keyword: Styrylphenanthrenes and aza-analogues / Photoisomerization / Photocyclization / Fluorescence parameters
- Aloisi, Gian Gaetano,Mazzucato, Ugo,Spalletti, Anna,Galiazzo, Guido
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p. 107 - 118
(2007/10/02)
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- SYNTHESIS OF DIARYLETHYLENES WITH CONDENSED RINGS BY THE WITTIG REACTION
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The Wittig reaction was used for the synthesis of diarylethylenes containing condensed naphthalene, anthracene, phenanthrene, and pyrene rings.Unlike 9-anthracenecarbaldehyde, which gives the trans isomers almost exclusively in the Wittig reaction with ar
- Listvan, V. N.,Gonchar, G. V.,Rudenko, E. S.,Onishchenko, T. A.,Stasyuk, A. P.
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p. 1528 - 1533
(2007/10/02)
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