Enantiomers of 3-amino-1-methyl-1,2-dicarba-closo-dodecaborane

Краснов, В. П.; Левит, Г. Л.; Charushin, Valery N.; Grishakov, A. N.; Кодесс, М. И.; Калинин, В. Н.; Ol’shevskaya, V. A.; Чупахин, О. Н.

doi:10.1016/s0957-4166(02)00474-3

Cited by 33 publications

(16 citation statements)

References 9 publications

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“…19,20 The individual enantiomers of 3 amino 1 methyl o carborane 1 were isolated through the resolution of its diastereomeric amides with (S) naproxen and subsequent acid hydrolysis of the individual diastereomers. [18][19][20] A mixture of stereoisomers, enriched with (S) enanti omer of 3 amino 1 phenyl o carborane 2, was obtained by kinetic resolution (KR) of racemic amine 2. 19,20 The kinetic resolution of racemic 3 amino 1 isopro pyl 1,2 dicarba closo dodecaborane (3) 31 was carried out by acylation with N phthaloyl L alanine acyl chloride (4) (Scheme 1), with the ratio amine : acyl chloride being 2 : 1, in benzene at room temperature.…”

Section: Resultsmentioning

confidence: 99%

Determination of enantiomeric purity of 1-substituted 3-amino-1,2-dicarba-closo-dodecaboranes by HPLC on chiral stationary phases

et al. 2008

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A determination of enantiomeric purity of 1 substituted (Me, Ph, and Pr i ) 3 amino 1,2 dicarba closo dodecaboranes by HPLC on chiral Chiralcel OD H and Chiralpac AD stationary phases involving preliminary phthaloylation of 3 aminocarboranes has been suggested as a general method.Carboranes, including dicarba closo dodecaboranes, are considered as compounds prospective for the develop ment of medicinal agents, especially for the boron neutron capture therapy (BNCT) of cancer. 1-5 Biological activity of such compounds should depend on their stereochemical structure. However, properties of chiral carboranes have not yet been studied. The reason for this is that the chemi cal methods for the preparation and identification of indi vidual carborane stereoisomers, the spatial isomerism of which is provided by arrangement of substituents in the carborane cage, are not yet enough developed.High performance liquid chromatography (HPLC) is widely used for separation and analysis of a great variety of cage organoboron compounds. 6 Thus, a separation of a number of 1 substituted 1,2 dicarba closo dodecabo ranes has been accomplished by reversed phase HPLC, 7 investigation have been made on separation of cobalt con taining boranes, 8 as well as of 1,2 dicarba closo dodeca borane derivatives using gel permeation chromatography and styrene divinylbenzene copolymer as the sorbent. 9At present, HPLC, in particular, HPLC on chiral sta tionary phases (CSP) remains the most important ana lytical instrument in chemistry of organoboron com pounds. 10-16 Phases based on β cyclodextrin (β CD), both the modified (acetyl β CD for a reversed phase chroma tography) and unmodified were used as the CSP. Analyti cal results on a wide number of chiral carboranes and met aloboranes showed a high efficiency of these CSP. Though Chiralcel OD H and Chiralpac AD are used for the sepa ration of enantiomers of various organic and organo element compounds, 17 in the literature, the data on their use for the analysis of chiral cage organoboron compounds are absent.The purpose of the present work is to study possibilities of application of HPLC on Chiralcel OD H and Chi ralpac AD chiral phases for the separation of planary chiral 1 substituted 3 amino 1,2 dicarba closo dodeca boranes 1-3. Results and DiscussionEarlier, 18-20 we have developed approaches to the preparation of individual stereoisomers of 1 methyl (1) and 1 phenyl 3 amino 1,2 dicarba closo dodecaborane (2). To determine enantiomeric purity of compounds, we used HPLC (on silica gel, a Lichrosorb Si 60 column) and 1 H NMR spectroscopy with preliminary derivatization of 3 amino 1,2 dicarba closo dodecaborane derivatives 1 and 2 with chiral derivatizing agents (CDA), viz., (S) naproxen acyl chloride, frequently used for this pur pose, 21-30 or N tosyl L proline and N phthaloyl L ala nine chlorides. 19,20The individual enantiomers of 3 amino 1 methyl o carborane 1 were isolated through the resolution of its

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Section: Resultsmentioning

confidence: 99%

Determination of enantiomeric purity of 1-substituted 3-amino-1,2-dicarba-closo-dodecaboranes by HPLC on chiral stationary phases

et al. 2008

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“…Recently, it has been shown that acidic hydrolysis of both (R, S) and (S, S) diastereomeric amides 3 results in the partial racemization of the target 3-aminocarborane 1 [3]. Hydrolysis of N-tosyl-(S)-prolyl amide 4 of 3-amino-1-methylcarborane (de 92%) during 14 h also resulted in the racemization of the target carborane 1 (ee 46%) (Scheme 1) [7].…”

Section: Resultsmentioning

confidence: 99%

“…Recently, we have obtained both enantiomers of 3-amino-1-methyl-1,2-dicarba-closo-dodecaborane (1) using (S)-naproxen chloride as a chiral resolving agent (CRA) [3]. Structural isomerism of such carboranes is caused by relative position of substituents in the carborane cage (Fig.…”

Section: Introductionmentioning

confidence: 99%

Acidic hydrolysis of N-acyl-1-substituted 3-amino-1,2-dicarba-closo-dodecaboranes

Левит

Demin

Кодесс

et al. 2005

Journal of Organometallic Chemistry

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“…Subsequent treatment of the reaction mass with water and acidification led to previously unknown 3-benzoyl -(11, 12), 3-acetyl-(13-15), 3-formyl-substituted (16, 17) C-carboranylacetic acids in 80-95% yields (Scheme 1). Introduction of a substituent into position 1 of 3-substituted o-carboranes makes these molecules chiral [7]. Therefore, the carborane amino acids obtained exist as corresponding pairs of enantiomers.…”

Section: Resultsmentioning

confidence: 99%