14769-74-5Relevant articles and documents
Total Synthesis of (+)-Granatumine A and Related Bislactone Limonoid Alkaloids via a Pyran to Pyridine Interconversion
Schuppe, Alexander W.,Zhao, Yizhou,Liu, Yannan,Newhouse, Timothy R.
, p. 9191 - 9196 (2019/06/17)
We report the first total synthesis of (+)-granatumine A, a limonoid alkaloid with PTP1B inhibitory activity, in ten steps. Over the course of this study, two key methodological advances were made: a cost-effective procedure for ketone α,β-dehydrogenation using allyl-Pd catalysis, and a Pd-catalyzed protocol to convert epoxyketones to 1,3-diketones. The central tetrasubstituted pyridine is formed by a convergent Knoevenagel condensation and carbonyl-selective electrocyclization cascade, which was followed by a direct transformation of a 2H-pyran to a pyridine. These studies have led to the structural revision of two members of this family.
Effect of ultrasound-assisted crystallization in the diastereomeric salt resolution of tetramisole enantiomers in ternary system with O,O′-dibenzoyl-(2R,3R)-tartaric acid
Szeleczky, Zsolt,Kis-Mihály, Erzsébet,Semsey, Sándor,Pataki, Hajnalka,Bagi, Péter,Pálovics, Emese,Marosi, Gy?rgy,Pokol, Gy?rgy,Fogassy, Elemér,Madarász, János
, p. 8 - 17 (2016/02/27)
The diastereomeric salt resolution of racemic tetramisole was studied using ultrasound irradiation. We examined the effect of power and duration of ultrasonic irradiation on the properties of the crystalline phase formed by ultrasound-assisted crystallization and the result of the whole optical resolution. The results were compared with reference experiment without using ultrasound. The US time (5-30 min) caused higher enantiomeric excess. Although yield was lower continuously high resolving efficiency could have been reached through ultrasound. We had the best results with 4.3 W ultrasound power when resolvability was even higher than the best of reference. Furthermore, we accomplished a deep and thorough examination of the salts that possibly could form in this resolution. One of the four diastereomeric salts, which have been identified by powder X-ray diffraction, FTIR-spectroscopy, and differential scanning calorimetry (DSC) in the ternary system of the two tetramisole enantiomers and the resolving agent, namely the bis[(S)-tetramisole]-dibenzoyl-(R,R)-tartrate salt have been proven the key compound in the resolution process, and presented the highest melting point of 166 °C (dec.) among the four salts. The originally expected diastereomeric bitartrate salts with 1:1 M base:acid ratio [(S)-tetramisole-dibenzoyl-(R,R)-hydrogen-tartrate salt and (R)-tetramisole-dibenzoyl-(R,R)-hydrogen-tartrate salt] and their 'racemic' co-crystal [(RS)-tetramisole-dibenzoyl-(R,R)-hydrogen-tartrate salt] showed somewhat lower melting points (152, 145, and 150 °C, respectively) and their crystallization was also prevented by application of ultrasound. Based on the melting points and enthalpies of fusion measured by DSC, all the binary and ternary phase diagrams have been newly established and calculated in the system with help of classical modelling equations of liquidus curves.
Effect of achiral support on the resolution of tetramisole by supercritical fluid extraction
Szekely, Edit,Simandi, Bela,Laszlo, Krisztina,Fogassy, Elemer,Pokol, Gyoergy,Kmecz, Ildiko
, p. 1429 - 1434 (2007/10/03)
The enantiomers of tetramisole were produced by partial diastereomeric salt formation with O,O′-dibenzoyl-(2R,3R)-tartaric acid monohydrate and subsequent supercritical fluid extraction (SFE) of the unreacted enantiomers in the presence of an achiral support. The effect of the activated carbon and Perfil 100 on the efficiency of chiral separation were studied. The kinetics of the process was found to be an important factor affecting enantioselectivity. When the parameters were properly set, much better resolution efficiency (F) and higher enantiomeric purity were achieved than in the equilibrium. The presence of Perfil 100 and activated carbon caused an increase as high as 53 and 84% in F, respectively, compared to that achieved without using any supporting material. Thus during the development of a resolution procedure, beside the proper resolution agent, optimised molar ratio and other parameters, the selection of achiral addict(s) may be also an important point.
Supercritical fluid extraction: A novel method for the resolution of tetramisole
Keszei, Sandor,Simandi, Bela,Szekely, Edit,Fogassy, Elemer,Sawinsky, Janos,Kemeny, Sandor
, p. 1275 - 1281 (2007/10/03)
A new resolution method, based on the selective distribution of enantiomers between a chiral solid and an achiral supercritical fluid phase, is reported. The chiral solid phase is formed from the optically active dicarboxylic acid derivative, (2R,3R)-O,O'-dibenzoyltartaric acid, and the racemic base (tetramisole). A new method is also described for the enrichment of enantiomeric mixtures which have an enantiomeric ratio other than 1:1. This is based on the partial salt formation of the enantiomeric mixture with an achiral substance, which is then followed by supercritical fluid extraction of the free enantiomer. The extract has an enantiomeric composition which is different from the starting mixture. The method is applied to an enantiomeric mixture of tetramisole with hydrochloric acid.
A CONVENIENT METHOD FOR OPTICAL RESOLUTIONS VIA DIASTEREOISOMERIC SALT FORMATION
Acs, M.,Fogassy, E.,Faigl, F.
, p. 2465 - 2470 (2007/10/02)
With the advantage of the method using two immiscible solvents and half-equivalent amount of the resolving agent, higher optical purity can be obtained than in cases of any other resolution via diastereoisomeric salt formation, besides it is a faster procedure for resolution of a new racemate as well.
