- Synergistic Catalysis for the Umpolung Trifluoromethylthiolation of Tertiary Ethers
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The first transition-metal-free, site-specific umpolung trifluoromethylthiolation of tertiary alkyl ethers has been developed, achieving the challenging tertiary C(sp3)–SCF3 coupling under redox-neutral conditions. The synergism of organophotocatalyst 4CzIPN and BINOL-based phosphorothiols can site-selectively cleave tertiary sp3 C(sp3)–O ether bonds in complex molecules initiated by a polarity-matching hydrogen-atom-transfer (HAT) event. The incorporation of several competing benzylic and methine C(sp3)?H bonds in alkyl ethers has little influence on the regioselectivity. Selective difluoromethylthiolation of C?O bonds has also been achieved. This represents not only an important step forward in trifluoromethylthiolation but also a promising means for site-selective C?O bond functionalization of unsymmetrical tertiary alkyl ethers.
- Xu, Wentao,Ma, Junyang,Yuan, Xiang-Ai,Dai, Jie,Xie, Jin,Zhu, Chengjian
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supporting information
p. 10357 - 10361
(2018/08/06)
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- (ALPHA-SUBSTITUTED ARALKYLAMINO AND HETEROARYLALKYLAMINO) PYRIMIDINYL AND 1,3,5-TRIAZINYL BENZIMIDAZOLES, PHARMACEUTICAL COMPOSITIONS THEREOF, AND THEIR USE IN TREATING PROLIFERATIVE DISEASES
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Provided herein are (alpha-substituted aralkylamino or heteroarylalkylamino) pyrimidinyl and 1,3,5-triazinyl benzimidazoles, e.g., a compound of Formula 1, and their pharmaceutical compositions, preparation, and use as agents or drugs for treating proliferative diseases
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Page/Page column 77
(2012/10/08)
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- Pd(II)-catalyzed hydroxyl-directed C-H olefination enabled by monoprotected amino acid ligands
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A novel Pd(II)-catalyzed ortho-C-H olefination protocol has been developed using spatially remote, unprotected tertiary, secondary, and primary alcohols as the directing groups. Mono-N-protected amino acid ligands were found to promote the reaction, and an array of olefin coupling partners could be used. When electron-deficient alkenes were used, the resulting olefinated intermediates underwent subsequent Pd(II)-catalyzed oxidative intramolecular cyclization to give the corresponding pyran products, which could be converted into ortho-alkylated alcohols under hydrogenolysis conditions. The mechanistic details of the oxidative cyclization step are discussed and situated in the context of the overall catalytic cycle.
- Lu, Yi,Wang, Dong-Hui,Engle, Keary M.,Yu, Jin-Quan
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supporting information; experimental part
p. 5916 - 5921
(2010/07/05)
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- The synthesis of new bronchodilator prodrugs
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Prodrug 14 has been synthesized to investigate its lung accumulating property while prodrugs 19, 20 and 22 incorporating structural features of 14 have been prepared for evaluation as bronchodilatory agents.
- Adams, Mortimer H.,Ameer, Farouk,Green, Ivan R.,Syce, James A.
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p. 2419 - 2430
(2007/10/03)
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- THE EFFECT OF ARYL SUBSTITUENTS ON ARYLCARBENE REACTIVITY
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Substituted (p-MeO, p-Me, H, p-Cl, p-Br, m-Br, m-MeO, 3,4-Cl2, p-CO2Me, m-CN and p-CN) monophenylcarbenes are generated in a binary mixture of substrates (methanol, cis-4-methyl-2-pentene and cyclohexane) and the relative rate of O - H insertion into methanol to stereospecific cyclopropanation of the olefin to C - H insertion into cyclohexane are calculated from the ratios of products and substrates.It is found (i) that the reactivities of the substrates decrease in the order of methanol, olefin and cyclohexane and (ii) that electron-donating substituents generally lead to reaction with the more reactive substrates while the reaction with the less reactive substrates is favoured in the case of electron-withdrawing substituents.These results are interpreted in terms of the change in the electrophilicity of the singlet arylcarbene by the substituents rather than the change in the singlet-triplet equilibrium.
- Tomioka, Hideo,Tabayashi, Kazuo,Ozaki, Yasuji,Izawa, Yasuji
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p. 1435 - 1440
(2007/10/02)
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- Effects of Substituents and Generation Methods on Insertion-Addition Selectivities of ''Arylcarbene'' in Alcohol-Olefin Binary Mixtures. Intervention of Reaction of Diazo Compounds Masquerading as Carbenes
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A Hammett study of the insertion-addition selectivity (Ki/ka) and cyclopropanation stereoselectivity (kc/kt) of "arylcarbene" generated either photolytically or thermally in 2-propanol-ethyl vinyl ether binary mixtures showed that ρ values are highly sensitive to the generation method.Thus, plots of ki/ka and kc/kt vs. ? (?+) in the photolytic run gave ρ values of -0.96 (r = -0.96) and -0.15 (r = -0.95), respectively, whereas similar values are +1.4 (r = 0.93) and -1.1 (r = -0.96) in the thermal run.The results along with the effects of precursor, temperature, and sensitizer on the product distributions are interpreted as indicating that, while free carbene is involved in the photolytic run, the ground-state diazo compound is masquerading as carbene in its thermal reaction with the olefin.
- Tomioka, Hideo,Suzuki, Shinji,Izawa, Yasuji
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p. 1047 - 1050
(2007/10/02)
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- Temperature and Substituent Effects on Regioselectivity in the Insertion of Arylcarbene into Alcohols
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Photolysis of aryldiazomethanes in methanol, ethanol, and 2-propanol gave OH insertion products along with small amounts of CH insertion products at ambient temperature.However, the CH insertion products increased significantly at the expense of the ether as the temperature was lowered.The attempted sensitized decomposition of the diazomethane did not lead to an increase in the CH insertion products presumably because of a rapid singlet-triplet equilibrium.The key intermediate leading to the CH insertion is suggested to be ground-state triplet arylcarbene, based on the accumulated spectroscopic as well as chemical evidence for the intervention of the triplet arylcarbene in the low-temperature photolysis of aryldiazomethanes.Substituents on the phenyl ring also have an appreciable effect on the insertion selectivity.At room temperature, the OH/CH insertion selectivity increased with the electron-donating ability of the substituents.This is interpreted in terms of the substituent effect on the transition state of OH insertion, where there is a deficiency of electrons at the benzylic carbon atom, rather than on the stability of singlet carbene.At low temperature, both electron-donating and -withdrawing substituents facilitate OH insertion, indicating the change in substituents induces a concomitant change in the insertion mechanism, presumably due to decreasing nucleophilicity of carbene with increasing electron-withdrawing ability as well as decreasing proton-donor activity of alcohol with decreasing temperature.This may also reflect the effect of the substituent on the singlet-triplet energy gap.
- Tomioka, Hideo,Suzuki, Shinji,Izawa, Yasuji
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p. 3156 - 3162
(2007/10/02)
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- Alkylwanderungen bei Sextettumlagerungen
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The migration aptitude of alkyl groups in the Beckmann-, the Criegee-, and the isonitrile-nitrile rearrangements were investigated.The relative rearrangement rates of substituted benzyl groups are an expression of the charge on the migrating carbon at transition state.From the relative rates of migration of exo- and endo-2-norbornyl groups the geometrical changes at the migrating carbon is estimated.Finally, the different influence of α-branching in the migrating group is discussed for these and some other rearrangements.
- Langhals, Heinz,Range, Guenter,Wistuba, Eckehardt,Ruechardt, Christoph
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p. 3813 - 3830
(2007/10/02)
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- 2-METHYL-1-(SUBSTITUTED)PHENYL-2-PROPYL ESTERS OF 2-AMINOPROPANOIC ACID
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A compound of the general formula and pharmaceutically acceptable salts thereof, in which formula the groups R0 are the same or different and are selected from the group consisting of hydrogen, halogen, alkyl having 1, 2 or 3 carbon atoms, and alkoxy having 1, 2 or 3 carbon atoms; R1 is hydrogen, methyl or ethyl; R2 is methyl or ethyl; R3 and R4 are the same or different and are hydrogen or an alkyl group having 1, 2 or 3 carbon atoms; and n is 0, 1 or 2. Pharmaceutical preparations containing these compounds are useful for treatment of depressive disorders
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- Inhibitors of neuronal monoamine uptake. II. Selective inhibition of 5-hydroxytryptamine uptake by α-amino acid esters of phenethyl alcohols
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A series of α-amino acid esters of substituted phenethyl alcohols was prepared and tested as inhibitors of the neuronal reuptake of noradrenaline and 5-hydroxytryptamine. Some of the compounds are potent and very selective in blocking the 5-hydroxytryptamine uptake, as evidenced by biochemical data and behavioral tests. The most promising agent, alaproclate [2-(4-chlorophenyl)-1,1-dimethylethyl 2-aminopropanoate hydrochloride (1,IV), was selected for further studies as a potential antidepressant agent. A discussion on structure-activity relationships (SAR) is given. In an attempt to explain the selective action on the mechanism of 5-hydroxytryptamine uptake by the new inhibitors, their structures are compared with those of the two neurotransmitters. From the tentative pharmacophore and conformations of transmitter (5-HT) and inhibitor (alaproclate) derived from SAR, a hypothetic carrier site for 5-HT uptake is deduced in terms of geometry and electronic properties.
- Lindberg,Thorberg,Bengtsson,Renyi,Ross,Ogren
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p. 448 - 456
(2007/10/06)
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