126597-34-0Relevant academic research and scientific papers
Functionalised organotitanium compounds: From lithium to titanium intermediates in chemoselective reactions with carbonyl compounds
Pastor, Isidro M,Yus, Miguel
, p. 2365 - 2370 (2001)
The reaction of functionalised organolithium compounds 1 with an equimolecular mixture of two carbonyl compounds in the presence of 2 equiv. of triisopropoxytitanium chloride can discriminate between aldehyde and ketone, the process being selective for al
Organocatalytic asymmetric synthesis of 1,1-diarylethanes by transfer hydrogenation
Wang, Zhaobin,Ai, Fujin,Wang, Zheng,Zhao, Wanxiang,Zhu, Guangyu,Lin, Zhenyang,Sun, Jianwei
supporting information, p. 383 - 389 (2015/01/30)
A new organocatalytic transfer hydrogenation strategy for the asymmetric synthesis of 1,1-diarylethanes is described. Under mild conditions, a range of 1,1-diarylethanes substituted with an o-hydroxyphenyl or indole unit could be obtained with excellent efficiency and enantioselectivity. We also extended the protocol to an unprecedented asymmetric hydroarylation of 1,1-diarylalkenes with indoles for the synthesis of a range of highly enantioenriched 1,1,1-triarylethanes bearing acyclic all-carbon quaternary stereocenters. These diaryl- and triarylethanes exhibit impressive cytotoxicity against a number of human cancer cell lines. Preliminary mechanistic studies combined with DFT calculations provided important insight into the reaction mechanism.
Catalytic Asymmetric 1,6-Conjugate Addition of para-Quinone Methides: Formation of All-Carbon Quaternary Stereocenters
Wang, Zhaobin,Wong, Yuk Fai,Sun, Jianwei
supporting information, p. 13711 - 13714 (2015/11/11)
Described herein is a general and mild catalytic asymmetric 1,6-conjugate addition of para-quinone methides (p-QMs), a class of challenging reactions with previous limited success. Benefiting from chiral Bronsted acid catalysis, which allows in situ formation of p-QMs, our reaction expands the scope to general p-QMs with various substitution patterns. It also enables efficient intermolecular formation of all-carbon quaternary stereocenters with high enantioselectivity.
Nonlinear solvent water effects in the excited-state (formal) intramolecular proton transfer (ESIPT) in m-hydroxy-1,1-diaryl alkenes: Efficient formation of m-quinone methides
Fischer, Maike,Wan, Peter
, p. 4555 - 4562 (2007/10/03)
The photohydration of hydroxy-substituted 1,1-diaryl alkenes 1-3 has been studied in aqueous CH3CN solution. Evidence for formation of quinone methide intermediates was provided by product studies and by observation of its absorption spectrum by laser flash photolysis. For the meta isomers, the proposed mechanism of m-quinone methide formation probably involves a solvent-mediated ("proton-relay") excited-state (formal) intramolecular proton transfer (ESIPT) from the phenol hydroxyl group to the β-carbon of the alkene moiety in neutral aqueous CH3CN solution, either in a concerted manner or via two very fast steps. The m-quinone methides are then trapped by water to form the corresponding diaryl ethanol product with high overall quantum yield. Evidence for the ESIPT pathway was provided by fluorescence and LFP measurements. The addition of small amounts of water (3CN) decreased the fluorescence emissions of 1 and 2 with a concomitant increase in production of m-quinone methides. Stem-Volmer analyses of fluorescence data revealed a dynamic and a minor static quenching component, both of which involved a water trimer cluster. The degree of charge transfer from the phenol (phenolate) oxygen to the alkene β-carbon, which may be thought of as the driving force for this efficient ESIPT, is pronounced for the meta isomer in the excited state, consistent with Zimmerman's "meta-ortho effect". Alkenes 1 and 2 were shown to be more efficient in m-quinone methide photogeneration than the hydroxy-substituted benzyl alcohol 8, which required conditions of higher water content for similar quantum yields.
Preparation of 1,1-diphenylethanols by addition of organotitanium compounds to substituted aceto- and benzophenones
Dimitrov,Stanchev,Milenkov,Nikiforov,Demirev
, p. 228 - 232 (2007/10/02)
The 1,1-diphenylethanols 5a-h were prepared by the addition of phenyltitanium triisopropoxide (3) to 4-substituted acetophenones 1a-h. The titanium tetraalkoxide 7, formed in situ from 3 and 1a, forms complexes with up to two molecules of 1a, this was established by 13C-NMR. Preparation of the alcohols 5a-f was also carried out by the reaction of methyltitanium triisopropoxide (4) with 4-substituted benzophenones 2a-f.
