AZIRIDINES IN THE SYNTHESIS OF 2',5'-DISUBSTITTUTED PYRROLOFULLERENES AND DUMBBELL-LIKE BIS-FULLERENE ENSEMBLES

Секция 3

Органическая химия

УСТНЫЕ ДОКЛАДЫ

 

 

AZIRIDINES IN THE SYNTHESIS OF 2',5'-DISUBSTITTUTED PYRROLOFULLERENES AND DUMBBELL-LIKE BIS-FULLERENE ENSEMBLES

 

Konev A.S.,¹ Petrovski P.P.²,Golovkina M.V.³

¹ Saint-Petersburg State University,

Saint-Petersburg, Russian Federation.

[email protected]

² Saint-Petersburg State University, Saint-Petersburg, Russian Federation.

Young scientist.

³ Saint-Petersburg State University, Saint-Petersburg, Russian Federation.

Six-year student.

Scientific adviser: Khlebnikov A.F.

 

Fullerene-containing molecules find application as pharmaceuticals^1,2, imaging agents¹, components of photo-voltaic devices^3,4, molecular electronics and in many other fields. 1,3-Dipolar cycloaddition of azomethine ylides across the [6,6]-juncture in C₆₀, known as Prato reaction, is one of the ways to introduce fullerene moiety into target molecule. The most used mode of performing this reaction involves in situ generation of azomethine-ylides from aldehydes and amines followed by their cycloaddition to C₆₀.⁵ This reaction suits perfectly for construction of 2',5'-unsubstituted pyrrolofullerenes. However, when one needs to sytnthesize 2',5'-disubstituted pyrrolofullerenes, other routes should often be sought as the stereochemical outcome of this reaction is not always predictable. To address this issue, we have turned our attention to another option for performing the above reaction, where azomethine-ylides are generated via ring-opening of aziridines, and which is much less studied.

To that end, we have performed a series of model studies on the reaction of dialkyl 1-arylaziridine-2,3-dicarboxylates (1,2) with fullerene C₆₀

and have found that the reaction is highly stereoselective and stereospecific, with cis -aziridines (1) yielding exclusively trans -adducts (3)and trans -aziridines (2) giving cis -adducts (4) (Scheme 1).

 

Scheme 1

The observed stereoselectivity and stereospecificity remain for much more complicated systems, such as azirino-fused dibenzoxazepines (5) and dibenzazepines (6), where only cis -cycloadducts (7,8) have been observed and isolated from the reaction of trans -aziridines with fullerene (Scheme 2).

Scheme 2

In addition to exclusive stereoselectivity, relatively mild reaction conditions (80ºC is sufficient for ring-opening of the aziridine ring) can be marked among the advantages of the aziridine-mediated mode of Prato reaction. This fact allowed us to perform the reaction of bis-aziridines (9) with fullerene C₆₀ in such a way that either mono- (10) or bis-fullerene cycloadducts (11) would prevail, on our choice, depending on whether harsher (100 ºC) or milder (80 ºC) reaction conditions were used (Scheme 3).

Scheme 3

To rationalize the observed stereoselectivity and the selectivity in the formation of either mono- or bis-fullerene cyloadducts in the case of bis-aziridines, we have performed a series of quantum-chemical calculations at DFT B3LYP/6-31G(d) level (ONIOM B3LYP/6-31G(d): B3LYP/STO-3G for fullerene-containing compounds). The results of the calculations are discussed in the report.

 

References:

[1] R. Partha, J.L.Conyers, International. J. Nanomedicine, 4, 261 (2009)

[2] T. Mashino, K. Shimotohno, N. Ikegami, D. Nishikawa, K. Okuda, K. Takahanshi, Sh. Nakamura, M. Mochizuki, Bioorganic&Med. Chem. Lett., 15, 1107 (2005)

[3] J.-F. Nierengarten,New J. Chem., 28, 1177 (2004).

[4] J. L. Segura, N. Martín, D. M. Guldi, Chem.Soc.Rev., 34, 31-47 (2005)

[5] V. Tomberli, T. Da Ros, S. Bosi, M. Prato, Carbon, 38, 1551 (2000)

 

We gratefully acknowledge the financial support of the Russian Foundation for Basic Research (project 11-03-00186) and Federal Grant-in-Aid Program «Human Capital for Science and Education in Innovative Russia» (Governmental Contract no. 16.740.11.0442).

 

 

CHARACTERIZATION OF VITAMIN E BLENDED ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE (UHMWPE)

 

Malik S..,¹ Jahan M. Shah²,Hafeez-Ullaha³

¹ Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650, Pakistan,

Islamabad, Pakistan.

third-year PhD student.

[email protected]

² Biomaterial Research Lab, Physics Department, University of Memphis, Memphis TN 38152, USA, Memphis, USA. young scientist.

³ Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650, Pakistan, Islamabad, Pakistan. young scientist.

Scientific adviser: Ikram M.