1271-66-5Relevant articles and documents
Formation of fulvene and dimethylenecyclopentenyl titanium complexes from bis(η5-tetramethylcyclopentadienyl)titanium(IV) precursors
Mach, Karel,Varga, Vojtech,Hanus, Vladimir,Sedmera, Petr
, p. 87 - 95 (1991)
A mixture of isomeric (Me4C5H)(Me3C5(CH2)H)TiMe compounds was obtained by thermally induced methane elimination from (Me4C5H)2TiMe2 at 130 deg C, analogous to the formation of (Me5C5)(Me4C5(CH2))TiMe.The compound (Me5C5)(Me3C5(CH2)2)Ti was newly prepared in 27percent yield by boiling a (Me5C5)2TiCl2-LiAlH4 mixture in toluene, followed by sublimation of the soluble product.By an analogous process, (Me4C5H)(Me2C5(CH2)2H)Ti was obtained in 10percent yield.Neither type of complex was formed by either method from titanocene derivatives with fewer methyl groups at cyclopentadienyl ligands.
1H and 13C NMR spectroscopic study of titanium(IV) species formed by activation of Cp2TiCl2 and [(Me4C5)SiMe2NtBu]TiCl2 with methylaluminoxane (MAO)
Bryliakov, Konstantin P.,Talsi, Evgenii P.,Bochmann, Manfred
, p. 149 - 152 (2004)
Using 13C and 1H NMR spectroscopy, the products of the reaction of Cp2TiCl2 with methylaluminoxane (MAO) at Al:Ti ratios of 5:1 to 300:1 have been identified as Cp2TiMeCl, Cp2TiMe2, [Cp2TiMe(μ-Cl)Cp2-TiCl]+[Me-MAO]- (II1), [Cp2TiMe(μ-Cl)Cp2TiMe]+[Me-MAO]- (II2), [Cp2TiMe(μ-Me)Cp2TiMe]+[Me-MAO]- (II3), the heterobinuclear ion pair [Cp2Ti(μ-Me)2AlMe2]+[Me-MAO] - (III), and a zwitterion-like intermediate, formulated as Cp2TiMe+←Me-Al-≡MAO (IV). In contrast, [(Me4C5)SiMe2NtBu]TiCl2/M AO gives only zwitterion-like, not heterobinuclear, species.
Azulichlorins and Benzocarbachlorins Derived Therefrom
Noboa, Mario A.,Abusalim, Deyaa I.,Lash, Timothy D.
, p. 11649 - 11664 (2019)
Acid-catalyzed condensation of azulidipyrrane aldehydes with a dihydrodipyrrin carbaldehyde afforded the first examples of azulichlorins. These macrocyclic products were isolated in a monoprotonated form, and the free bases proved to be somewhat unstable. The monocations were strongly diatropic, and proton NMR spectroscopy showed the internal C-H at ca. -2 ppm. Addition of TFA gave the related dications, but these exhibited significantly reduced aromatic ring currents. Reaction of an azulichlorin with tert-butyl hydroperoxide and KOH in dichloromethane/methanol gave a benzocarbachlorin and two related aldehydes. The UV-vis spectrum for the benzocarbachlorin showed a split Soret band at 414 and 430 nm, together with a strong chlorin-like absorption at 684 nm. The proton NMR spectrum indicated that the carbachlorin is strongly aromatic and the internal C-H was observed at -4.64 ppm. Addition of TFA afforded a C-protonated dication with a significantly increased diatropic ring current. The proton NMR spectrum, NICS calculations, and AICD plots indicated that the system favors a 22πelectron delocalization pathway that runs through the fused benzo unit. Addition of TFA to the benzocarbachlorin aldehydes primarily led to the formation of monocations, and the generation of C-protonated dications was no longer favored due to the presence of electron-withdrawing formyl moieties.
Preparation of (+)-nemorensic acid and approaches to nemorensine using the partial reduction of electron deficient furans
Donohoe, Timothy J.,Guillermin, Jean-Baptiste,Walter, Daryl S.
, p. 1369 - 1375 (2002)
Starting from a commercially available furoic acid, the synthesis of (+)-nemorensic acid is described in nine steps, and in 32% overall yield. Key steps in our sequence are a chiral auxiliary controlled, stereoselective, Birch reduction of 3-methyl-2-furo
Ott,K.C.,Grubbs,R.H.
, p. 5922 (1981)
Oxidation Under Reductive Conditions: From Benzylic Ethers to Acetals with Perfect Atom-Economy by Titanocene(III) Catalysis
Funk, Pierre,Richrath, Ruben B.,Bohle, Fabian,Grimme, Stefan,Gans?uer, Andreas
supporting information, p. 5482 - 5488 (2021/02/03)
Described here is a titanocene-catalyzed reaction for the synthesis of acetals and hemiaminals from benzylic ethers and benzylic amines, respectively, with pendant epoxides. The reaction proceeds by catalysis in single-electron steps. The oxidative addition comprises an epoxide opening. An H-atom transfer, to generate a benzylic radical, serves as a radical translocation step, and an organometallic oxygen rebound as a reductive elimination. The reaction mechanism was studied by high-level dispersion corrected hybrid functional DFT with implicit solvation. The low-energy conformational space was searched by the efficient CREST program. The stereoselectivity was deduced from the lowest lying benzylic radical structures and their conformations are controlled by hyperconjugative interactions and steric interactions between the titanocene catalyst and the aryl groups of the substrate. An interesting mechanistic aspect is that the oxidation of the benzylic center occurs under reducing conditions.
Annulated bacteriochlorins for near-infrared photophysical studies
Fujita, Hikaru,Jing, Haoyu,Krayer, Michael,Allu, Srinivasarao,Veeraraghavaiah, Gorre,Wu, Zhiyuan,Jiang, Jianbing,Diers, James R.,Magdaong, Nikki Cecil M.,Mandal, Amit K.,Roy, Arpita,Niedzwiedzki, Dariusz M.,Kirmaier, Christine,Bocian, David F.,Holten, Dewey,Lindsey, Jonathan S.
, p. 7209 - 7232 (2019/05/24)
Molecules with strong absorption in the near-infrared (NIR) spectral region are of interest for a variety of applications in the photosciences. Nature's NIR absorbers are bacteriochlorophylls, which contain a tetrahydroporphyrin chromophore accentuated by
