- Thermal Rearrangements of 9,10-Bis(trifluorovinyl)phenanthrene
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Results from a study of the thermal unimolecular rearrangement of 9,10-bis(trifluorovinyl)phenanthrene are reported.Kinetic and product studies indicate that it is unexpectedly resistant to rearrangement, that its expected 6? electrocyclic rearrangement plays but a minor role, and that the major rearrangement process was a virtually unprecedented thermal reaction for 1,3,5-trienes, that of conversion to a bicyclohex-2-ene system (7).Activation parameters are provided for the minor electrocyclic process (ΔH(excit.) = 29.9 kcal/mol; ΔS(excit.) = -19.6 eu) and for the conversion to 7 (ΔH(excit.) = 34.4 kcal/mol; ΔS(excit.) = -6.6 eu) as well as for the secondary conversions of 7 to 4-(difluoromethylidene)-3,3,5,5-tetrafluoro-1,2-(9,10-phenanthro)cyclopent-1-ene (8) (ΔH(excit.) = 31.3 kcal/mol; ΔS(excit.) = -12.7 eu) and to 1,2-(9,10-phenanthro)-3,5,5-trifluoro-4-(trifluoromethyl)-1,3-cyclopentadiene (9) (ΔH(excit.) = 31.4 kcal/mol; ΔS(excit.) = -13.4 eu).A rarely encountered fluorine steric effect deriving from the stringent steric demands of the reaction's boat-like transition state is invoked to explain the inhibition of 1's electrocyclic process, while equally rare thermal 1,2-fluorine atom shifts are proposed to explain the rearrangement of 7.
- Dolbier, William R.,Palmer, Keith W.
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- Phenanthrene-fused azo-ene-ynes: Synthesis of dibenzo[ f, h ]cinnoline and dibenzo[ e, g ]isoindazole derivatives
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The cyclization reactions of a phenanthreno-fused azo-ene-yne compound have been studied both experimentally and computationally. Experimental results show that this system is prone to dimerization, more so than previously studied naphthalene- and benzene-based analogues. Calculations reveal that pyrazoles and arene-fused pyrazoles strongly stabilize carbenes in the 5-position through coarctate conjugation, suggesting a stationary concentration of the carbenes/carbenoids during cyclization that is high enough for dimerization.
- Young, Brian S.,Koehler, Felix,Herges, Rainer,Haley, Michael M.
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- In a Quest for Selectivity Paired with Activity: A Ruthenium Olefin Metathesis Catalyst Bearing an Unsymmetrical Phenanthrene-Based N-Heterocyclic Carbene
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Robust, selective, and stable in the presence of ethylene, ruthenium olefin metathesis pre-catalyst, {[3-benzyl-1-(10-phenyl-9-phenanthryl)]-2-imidazolidinylidene}dichloro(o-isopropoxyphenylmethylene)ruthenium(II), Ru-3, bearing an unsymetrical N-heterocyclic carbene (uNHC) ligand, has been synthesized. The initiation rate of Ru-3 was examined by ring-closing metathesis and cross-metathesis reactions with a broad spectrum of olefins, showing an unprecendented selectivity. It was also tested in industrially relevant ethenolysis reactions of olefinic substrates from renewable feedstock with very good yields and selectivities.
- D?browski, Micha?,Grela, Karol,Trzybiński, Damian,Wo?niak, Krzysztof,Wyr?bek, Przemys?aw
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supporting information
(2020/03/19)
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- NOVEL RUTHENIUM COMPLEX, METHOD OF ITS PRODUCTION AND ITS USE IN REACTION OF OLEFINE METATHESIS
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The invention relates to novel ruthenium complexes of formula (9). The invention also relates to the method for preparation of novel metal complexes of formula (9) and their use in olefin metathesis reactions.
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Page/Page column 17-18
(2018/06/22)
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- Sonogashira coupling using bulky palladium-phenanthryl imidazolium carbene catalysis
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(Matrix presented) Bulky phenanthracenyl imidazolium-derived carbene ligands were investigated for copper-free Sonogashira coupling with terminal acetylenes. Aryl bromides and iodides gave coupled products in excellent yields from the Pd(PPh3)2Cl2 complex with potassium t-butoxide and 18-crown-6 in THF. A remarkable dependence on the size of the ligand was found. The highest yields were obtained with the bulky 2,9-dicyclohexyl-10-phenanthryl ligand 5.
- Ma, Yudao,Song, Chun,Jiang, Wei,Wu, Quansheng,Wang, Yong,Liu, Xueying,Andrus, Merritt B.
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p. 3317 - 3319
(2007/10/03)
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