|
ИСТИНА |
Войти в систему Регистрация |
Интеллектуальная Система Тематического Исследования НАукометрических данных |
||
New Approach to Enantiopurity Determination of CN-Palladacyclesтезисы доклада
- Авторы: Dunina V.V., Gorunova O., Grishin Yu, Livantsov M., Kochetkov K.
- Сборник: Book of abstracts, Bit’c 3rd Annual Congress of Catalytic Asymmetric Synthesis (WCCAS-2012)
- Тезисы
- Год издания: 2012
- Место издания: Beijing, China
- Первая страница: 98
- Последняя страница: 98
- Аннотация: The chiral azapalladacycles have found wide use as reagents for racemate resolution, enantiomeric purity determination, asymmetric synthesis, and more recently – as enantioselective catalysts. All these applications require correct information regarding their enantiomeric composition. Conventional approach is based on chiral derivatizing with an alpha-amino acidate auxiliary ligand following by determination of diastereomer ratio using the 1H NMR spectroscopy. However, employment of such method becomes to be highly problematical in the case of CN-palladacycles of complicated structure. Our research was devoted to application of the 31P NMR spectroscopy for solution of this analytical task. The key to this idea implementation was the usage of P-donor chiral derivatizing agent. As the reagent of this kind we have selected the phosphinite derivative (RC)-Q of the available terpene (1R,2S,5R)-menthol. The efficiency of this approach is illustrated below by the examples of planar chiral CN-palladacycles derived from [2.2]paracyclophane imine (D1) and N,N-dimethylaminomethylferrocene (D2) (Scheme). This method seems to be especially valuable for the case of CN-palladacycles prepared by asymmetric cyclopalladation, exemplified here by scalemic dimer (Spl)-2. 31P NMR spectrum of its phosphinite derivative contains two signals of (Spl,RC)-2 and (Rpl,RC)-2 diastereomers in 95.5:4.4 integral ratio, corresponding to its enantiomeric enrichment to 91% ee. To note, only one signal was observed in the 31P NMR spectrum of phosphinite derivative (Rpl,RC)-1 of optically active imine dimer D1, that confirms its complete enantiomeric purity (>98% ee). Several advantages of this method have to be mentioned: (i) diastereomeric phosphinite derivatives 1 and 2 are quantitatively formed in situ at room temperature; (ii) the reagent (RC)-Q coordination with CN-palladacycles occurs regiospecifically in trans(P,N)-geometry; (iii) tight phosphinite bonding excludes any complications from dynamic processes; (iv) a rather large diastereomeric signal dispersion for adducts (Spl,RC)/(Rpl,RC)-1 and (Spl,RC)/(Rpl,RC)-2 derived from racemic dimers rac-D1 and rac-D2 (9.5 and 1.4 ppm, respectively) provides high exactness in determination of CN-palladacycle enantiomeric composition; (v) this method is universal and applicable to any non-phosphorous palladacycles.
- Добавил в систему: Дунина Валерия Владимировна