- Diquats with Robust Chirality: Facile Resolution, Synthesis of Chiral Dyes, and Application as Selectors in Chiral Analysis
-
Diquats with extremely high racemization barriers with ΔG≠theor of 233 kJ mol?1 at 180 °C are described. Reported configurational robustness is due to a combination of two structural features: the rigid o-xylylene tether connecting the nitrogen atoms and the presence of two substituents in the bay region of the bipyridinium scaffold. The straightforward synthesis of diquats, plus facile resolution and derivatization make them attractive for chiral application studies. This is demonstrated by: 1) synthesis of the first non-racemic diquat dyes with pronounced chiroptical properties, and 2) capability of diquats to interact stereospecifically with chiral molecules. This suggests potential for diquat derivatives to be used as chiral selectors in separation methods.
- Talele, Harish R.,Koval, Du?an,Severa, Luká?,Reyes-Gutiérrez, Paul E.,Císa?ová, Ivana,Sázelová, Petra,?aman, David,Bednárová, Lucie,Ka?i?ka, Václav,Teply, Filip
-
-
Read Online
- SYNTHESIS AND RESOLUTION OF NICOTINE
-
The present disclosure generally relates to methods of preparing nicotine and resolving R,S nicotine to enrich the (S)(?) enantiomer. The method may comprise combining N-methyl-2-pyrrolidone or a salt thereof with a nicotinate compound in the presence of a solvent and a strong base to form 1-methyl-3-nicotinoyl-2-pyrrolidone or a salt thereof; and reducing the 1-methyl-3-nicotinoyl-2-pyrrolidone or salt thereof in solution with Na2S2O4 to produce racemic nicotine or salt thereof. Resolving the racemic nicotine (or other enantiomeric mixture) may comprise combining the nicotine with (?)-O,O′-di-p-toluoyl-L-tartaric acid (L-PTTA).
- -
-
Paragraph 0039-0042
(2016/11/28)
-
- NOVEL RESOLUTION PROCESS FOR PREGABALIN
-
Present invention relates to a novel and improved process for the resolution of racemic pregabalin of formula (I) into (S)-(+)-pregabalin [(S)-(+)-3-aminomethyl-5-methylhexanoic acid] of formula (III) via the novel acid addition salt [(S)-(+) 3-aminomethyl-5-methylhexanoic acid, (-)-O, O'-di-p-toluoyl-L-tartaric acid salt] of formula (II). (S)-(+)-pregabalin of formula-III has analgesic, anticonvulsant and anxiolytic properties and hence is of great therapeutic significance.
- -
-
Page/Page column 6; 15
(2009/05/29)
-
- Processes for the preparation of (R)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol"
-
The present invention provides various processes for the preparation of (R)-±-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol. These processes may be characterized by the following scheme:
- -
-
Page/Page column 52-53
(2010/11/25)
-
- Novel processes for the preparation of (R)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol
-
The present invention provides various processes for the preparation of (R)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol. These processes may be characterized by the following scheme:
- -
-
-
- Novel processes for the preparation of adenosine compounds and intermediates thereto
-
Novel processes for the preparation of adenosine compounds and intermediates thereto. The adenosine compounds prepared by the present processes may be useful as cardiovascular agents, more particularly as antihypertensive and anti-ischemic agents, as cardioprotective agents which ameliorate ischemic injury or myocardial infarct size consequent to myocardial ischemia, and as an antilipolytic agents which reduce plasma lipid levels, serum triglyceride levels, and plasma cholesterol levels. The present processes may offer improved yields, purity, ease of preparation and/or isolation of intermediates and final product, and more industrially useful reaction conditions and workability.
- -
-
-
- Novel processes for the preparation or (R)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol
-
The present invention provides various processes for the preparation of (R)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenyl)ethyl]-4-piperidinemethanol. These processes may be characterized by the following scheme:
- -
-
-
- Resolution of (+/-)-propranolol.
-
Two improvements in propranolol resolution were developed. Both the (+)- and (-)-di-(p-toluoyl)tartaric acids were used as the resolving agents. This procedure reduced the number of crystallizations needed to obtain a pure product. Furthermore, synthesis of the resolving agent was improved.
- Yost,Holtzman
-
p. 1181 - 1182
(2007/10/06)
-
