24821-22-5Relevant articles and documents
A re-investigation of the reaction of hemimellitic acid with sulphur tetrafluoride. A simple preparation of 2,6-bis(trifluoromethyl)benzoic acid
Dmowski, Wojciech,Wiszniewski, Wojciech
, p. 163 - 165 (1997)
The reaction of hemimellitic acid (1) with SF4/HF gives a 1 : 3.5 : 13 mixture of 1,2,3-tris(trifluoromethyl)benzene (2), 1,1,3,3-tetrafluoro-4-trifluoromethyl-1,3-dihydroisobenzofuran (3) and 2,6-bis(trifluoromethyl)benzoyl fluoride (4). Treatment of the crude reaction mixture with aqueous KOH, followed by acidification of the water phase, gives a good yield of pure 2,6-bis(trifluoromethyl)benzoic acid (5).
Hexaphyrin as a Potential Theranostic Dye for Photothermal Therapy and 19F Magnetic Resonance Imaging
Higashino, Tomohiro,Nakatsuji, Hirotaka,Fukuda, Ryosuke,Okamoto, Haruki,Imai, Hirohiko,Matsuda, Tetsuya,Tochio, Hidehito,Shirakawa, Masahiro,Tkachenko, Nikolai V.,Hashida, Mitsuru,Murakami, Tatsuya,Imahori, Hiroshi
, p. 951 - 959 (2017/05/26)
Two features of meso-Aryl-substituted expanded porphyrins suggest suitability as theranostic agents. They have excellent absorption in near infrared (NIR) region, and they offer the possibility of introduction of multiple fluorine atoms at structurally equivalent positions. Here, hexaphyrin (hexa) was synthesized from 2,6-bis(trifluoromethyl)-4-formyl benzoate and pyrrole and evaluated as a novel expanded porphyrin with the above features. Under NIR illumination hexa showed intense photothermal and weak photodynamic effects, which were most likely due to its low excited states, close to singlet oxygen. The sustained photothermal effect caused ablation of cancer cells more effectively than the photodynamic effect of indocyanine green (a clinical dye). In addition, hexa showed potential for use in the visualization of tumors by 19F magnetic resonance imaging (MRI), because of the multiple fluorine atoms. Our results strongly support the utility of expanded porphyrins as theranostic agents in both photothermal therapy and 19F MRI.
Method for estimating SN1 rate constants: Solvolytic reactivity of benzoates
Matic, Mirela,Denegri, Bernard,Kronja, Olga
supporting information, p. 8986 - 8998,13 (2012/12/12)
Nucleofugalities of pentafluorobenzoate (PFB) and 2,4,6-trifluorobenzoate (TFB) leaving groups have been derived from the solvolysis rate constants of X,Y-substituted benzhydryl PFBs and TFBs measured in a series of aqueous solvents, by applying the LFER equation: log k = sf(Ef + Nf). The heterolysis rate constants of dianisylmethyl PFB and TFB, and those determined for 10 more dianisylmethyl benzoates in aqueous ethanol, constitute a set of reference benzoates whose experimental ΔG ? have been correlated with the ΔH? (calculated by PCM quantum-chemical method) of the model epoxy ring formation. Because of the excellent correlation (r = 0.997), the method for calculating the nucleofugalities of substituted benzoate LGs have been established, ultimately providing a method for determination of the SN1 reactivity for any benzoate in a given solvent. Using the ΔG? vs ΔH? correlation, and taking sf based on similarity, the nucleofugality parameters for about 70 benzoates have been determined in 90%, 80%, and 70% aqueous ethanol. The calculated intrinsic barriers for substituted benzoate leaving groups show that substrates producing more stabilized LGs proceed over lower intrinsic barriers. Substituents on the phenyl ring affect the solvolysis rate of benzhydryl benzoates by both field and inductive effects.
Crystallization-induced asymmetric transformation: stereospecific synthesis of L-768,673
Shi, Yao-Jun,Wells, Kenneth M.,Pye, Philip J.,Choi, Woo-Baeg,Churchill, Hywyn R. O.,et al.
, p. 909 - 918 (2007/10/03)
A highly convergent, asymmetric synthesis of L-768,673, an Iks Class III antiarrythmic drug candidate, is described. Synthesis of the racemic 1-trifluoroethyl-3-amino-5-phenyl benzodiazepinone was achieved by Ru-catalyzed hydrogenation of the corresponding oxime that was derived from commercially available 1-trifluoroethyl-5-phenyl benzodiazepine in 76 percent overall yield. An efficient one-pot resolution-racemization of (+/-)-amine provided the desired (+)-amine as its mandelate salt in 92 percent yield and 99.4 percent ee. Regioselective ortho-lithiation of 1,3-bis(trifluoromethyl)benzene with n-BuLi in the presence of a catalytic amount of 2,2',6,6'-tetramethylpiperidine afforded its aryl lithium. Subsequent transmetalation and alkylation with allyl bromide produced the corresponding olefin. Ru-catalyzed oxidative cleavage of the terminated double bond of the olefin provided the desired 2,4-bis(trifluoromethyl)phenylacetic acid in 35 percent overall yield. A modified Schotten-Baumman procedure was developed for coupling of (+)-amine and the acid to produce L-768,673 in 92 percent yield without racemization. - Keywords: Asymmetric synthesis; Benzodiazepines; Oximes; Resolution-racemization
Bis- and oligo(trifluoromethyl)benzenes: Hydrogen/metal exchange rates and gas-phase acidities
Schlosser, Manfred,Mongin,Porwisiak, Jacek,Dmowski, Wojciech,Bueker, Heinz H.,Nibbering, Nico M. M.
, p. 1281 - 1286 (2007/10/03)
The proton mobilities (kinetic acidities) of bis- and tris(trifluoromethyl)benzene are dictated to a large extent by steric factors; the trifluoromethyl group is a fairly bulky substituent that can seriously impede the approach of the metalating reagent. Most Satisfactory results in terms of yields and selectivities have been achieved with lithium 2,2,6,6-tetramethylpiperidide or with methyllithium in the presence of potassium tert-butoxide, a slim version of the standard superbase. The rates of deprotonation under irreversible conditions do not parallel the thermodynamic (equilibrium) acidities. Substituent effects on the deprotonation energies in the gas phase appear to be additive: each trifluoromethyl group lowers it by 13 kcal mol-1 when located ortho with respect to the carbanion, and by 10 kcal mol-1 when located in a meta or para position.
A site selective functionalisation of 1,3-bis(trifluoromethyl)benzene
Dmowski, Wojciech,Piasecka-Maciejewska, Krystyna
, p. 6781 - 6792 (2007/10/03)
1,3-Bis(trifluoromethyl)benzene was regioselectively metalated and subsequently carboxylated at position 2 to give 2,6- bis(trifluoromethyl)benzoic acid. Treatment of the acid with sulphur tetrafluoride gave 2,6-bis(trifluoromethyl)benzoyl fluoride which was readily convened to 2,6-bis(trifluoromethyl)benzyl alcohol and further to 2,6- bis(trifluoromethyl)benzaldehyde. Bromination of 2,6- bis(trifluoromethyl)benzoic acid with 1,1-dibromo-5,5-dimethylhydantoin proceeded regioselectively affording 4-bromo-2,6-bis(trifluoromethyl)benzoic acid almost quantitatively. The latter was fluorinated to the corresponding acid fluoride which on treatment with methanolic sodium methoxide gave 4- methoxy-2,6-bis(trifluoromethyl)benzoic acid or its methyl ester, depending on the reaction conditions. 4-Methoxy-2,6-bis(trifluoromethyl)benzoic acid, via its acid fluoride, was also transformed, first to the corresponding benzyl alcohol, then to the benzaldehyde. Lithiation of 4-methoxy-2,6- bis(triflouromethyl)benzoic acid, followed by methylation, proceeded with low selectivity, nevertheless, methyl 4-methoxy-3-methyl-2,6- bis(trifluoromethyl)benzoate was formed as the main product which was stepwise converted to 4-methoxy-3-methyl-2,6-bis(trifluoromethyl)benzyl alcohol and 4-methoxy-3-methyl-2,6-bis(trifluoromethyl) benzaldehyde, albeit in low total yield.
