20685-08-9Relevant academic research and scientific papers
Tricylic amino-acid derivatives
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, (2008/06/13)
Described herein are compounds which have the general formula: or a prodrug or pharmaceutically acceptable salt, solvate or hydrate thereof wherein: R1 is selected from the group consisting of H, alkyl and the counter ion for a basic addition salt; X is selected from the group consisting of CR9R10, S, O, SO, SO2, NH and N-alkyl; R2, R3, R4, R9 and R10 are independently selected from the group consisting of H and alkyl; R5 and R6 are independently selected from the group consisting of H, alkyl and phenyl, or, alternatively, R5 and R6 together may form a methylene group or a 3- to 6-membered a spirocyclic group; wherein, when X is CR9R10, one or both pairs of R5 and R9 or R6 and R10 may join to form a double or triple bond R7 is selected from the group consisting of Formula II-V: which are all optionally substituted, at nodes other than R8, with 1-4 substituents independently selected from the group consisting of alkyl, halo, aryl (which may be substituted as for R8), trifluoromethyl, trifluoromethoxy, nitro, cyano, amino, mono-alkylamino, di-alkylamino, alkoxycarbonyl, alkylcarbonyl, alkoxythiocarbonyl, alkylthiocarbonyl, alkoxy, alkylS-, phenoxy, -SO2NH2, -SO2NHalkyl, -SO2N(alkyl)2 and 1,2-methylenedioxy; and wherein any of the benzo-fused rings in structures II to V may be replaced by a 5- or 6-membered heterocyclic ring selected from the group consisting of pyridine, thiophene, furan and pyrrole; wherein R8 is selected from the group consisting of H, alkyl, benzyl, cycloalkyl, indanyl and an optionally substituted aryl group, wherein the optional substituents are independently selected from 1-4 members of the group consisting of alkyl, halo, aryl, trifluoromethyl, trifluoromethoxy, nitro, cyano, amino, mono-alkylamino, di-alkylamino, alkoxycarbonyl, alkylcarbonyl, alkoxythiocarbonyl, alkylthiocarbonyl, alkoxy, alkylS-, phenoxy, -SO2NH2, -SO2NHalkyl, -SO2N(alkyl)2 and 1,2-methylenedioxy; -represents a single or double bond; Y is selected from the group consisting of O, S, SO, NH, N-alkyl, CH2, CH-alkyl, C(alkyl)2, and C=O; Z is selected from the group consisting of CH2, O, S, NH and N-alkyl when-is a single bond; Z is selected from the group consisting of CH and N when-is a double bond. Also described is the use of these compounds as pharmaceuticals.
Unverbrueckte fluorenylkomplexe des typs (C5H5)(9-R-C13H8)ZrCl2 (R = Me3Si, Alkyl, Aryl): Synthese, charakterisierung und anwendung als katalysatoren bei der homogenen olefinpolymerisation
Schmid, Michael A.,Alt, Helmut G.,Milius, Wolfgang
, p. 15 - 22 (2007/10/03)
The reaction of various 9-substituted fluorene compounds (9-R-C13H9) (R = Me3Si, alkyl, aryl) (1a-i) with butyllithium followed by treatment with (C5H5)ZrCl3 leads to unbridged fluorenyl complexes of the type (C5H5)(9-R-C13H8)ZrCl2 (2a-i). In combination with methylaluminoxane, complexes 2a-i show a high catalytic activity as homogeneous ethylene polymerization catalysts. Compounds 2c (R = iPr), 2d (R = cyclohexyl), and 2e (R = tBu) were characterized by X-ray structure analyses.
Flash photolysis study of a Friedel-Crafts alkylation. Reaction of the photogenerated 9-fluorenyl cation with aromatic compounds
McClelland, Robert A.,Cozens, Frances L.,Li, Jianhui,Steenken, Steen
, p. 1531 - 1544 (2007/10/03)
A combination of flash photolysis and product analysis is employed to investigate the reaction of aromatic compounds (ArH) with the 9-fluorenyl cation (Fl+) photogenerated from 9-fluorenol in 1,1,1,3,3,3-hexafluoroisopropyl alcohol (HFIP).The availability of the photochemical route to Fl+ means that the reaction of benzylic-type cation with ArH can be directly followed by flash photolysis.An additional feature with electron-rich ArH is that the cyclohexadienyl cation is observed to grow as Fl+ decays.Thus both cationic intermediates of a Friedel-Crafts alkylation are observed in the same experiment.The formation of the cyclohexadienyl cation is demonstrated to be reversible, or at least quasi-reversible, with the kinetic analysis furnishing absolute rate constants for the formation of this cation as well as for its loss of H+ and Fl+.Values of kH:kD for benzene:benzene and toluene:toluene are ca. 1.5 and demonstrate that Fl+ addition is at least partly reversible with these compounds as well.The Hammett ρ+ value obtained for a series of the less electron-rich ArH is -8, indicative of a transition state with considerable cyclohexadienyl cation character.Anisole shows a negative deviation from from Hammett correlation line, explained by the addition of Fl+ to ArH becoming encounter-controlled.This behaviour is dramatically illustrated in a comparison of data for Fl+ and Br2.For the less electron-rich ArH, rate constants for the two electrophiles are parallel.However, from m-xylene through pentamethylbenzene, the rate with Fl+ is unchanged, while the rate with Br2 increases over 1000-fold.The concept of encounter control with Fl+ is strongly supported by the absolute rate constants, which for the electron-rich ArH are all in the range 1-2 E9 dm3 mol-1 s-1, a magnitude typical of diffusion-controlled reactions.The electron-rich ArH also show no intermolecular selectivity since their reactions are encounter-controlled, but have a high intramolecular selectivity.It is suggested that a factor influencing the latter is the reversibility of formation of the cyclohexadienyl cation from the encounter complex.
Versatile and Convenient Lattice Hosts derived from Singly Bridged Triarylmethane Frameworks, X-Ray Crystal Structures of Three Inclusion Compounds
Weber, Edwin,Doerpinghaus, Norbert,Csoeregh, Ingeborg
, p. 2167 - 2177 (2007/10/02)
A new family of host molecules, based on the singly bridged triarylmethanol and triarylacetic acid frameworks, is described.These hosts form crystalline inclusions with a variety of uncharged organic molecules ranging from protic dipolar to apolar compounds (130 different species).The formation and stoicheiometry depend in a systematic manner on structural parameters of the host, such as the nature of the functional group and the substituents, and on the substituent positions.The crystal structures of three inclusion compounds have been studied by X-ray diffraction.They reveal the building principles of the new inclusion family.In the crystals of 1a*benzene (8:3), the benzene is interstitially entrapped by H-bonded tetramer clusters of 1a.Crystals of 1a*dioxane (4:3) are built of H-bonded 2:1 host-guest complexes including interstitial molecules of dioxane.In the case of 4c*EtOH (1:1), the building principle is formation of 2:2 host-guest clusters via a twelve-membered H-bonded ring.
A Novel Redox Reaction of the Disulphide Dication Salt (R2S+-+SR2*2X-) with Carbanions and Alkoxides
Fujihara, Hisashi,Akaishi, Ryouichi,Furukawa, Naomichi
, p. 147 - 148 (2007/10/02)
The disulphide dication salt, 1,5-dithioniabicyclooctane bis(trifluoromethanesulphonate) (1) was reduced upon treatment with carbanions or alkoxides; it did not deprotonate.
Kinetic Hydrogen Isotope Effects in Intermolecular Hydride Transfer from Arylalkanes to 9-Arylfluoren-9-yl Cations
Bethell, Donald,Hare, Gerard J.,Kearney, Paul A.
, p. 684 - 691 (2007/10/02)
Rates of hydride-ion transfer to a series of 9-phenylfluoren-9-yl cations, substituted in the phenyl group, from triphenylmethane and 4,4'-dimethoxydiphenylmethane have been measured at 30 degC in trifluoroacetic acid solution containing 6percent v/v acet
