Journal of Gyansagar Science Foundation 2013 04 01

Author(s): Sanjeev Sogani, Vimal Jain
Publisher: Gyansagar Science Foundation

Page 47

Vimal K. Jain, Volume 1 Issue 1 April 2013
(ii) Diorgano diselenides: (HOOC-CH,Se),;
(HOOC-CH,CH,Se); (HOOC-CH,CH,CH,Se), (HO-CH CH Se),; (HO-CH CH, CH, Se),; (H, N
CH,CH, Se),; (H2N-CH CH, CH, Se), (iii) Pyrazole based derivatives (iv) Nicotinamide based derivatives
21st essential amino acid.
Having recognized the role of selenium in biochemical reactions, scientific community has been infatuated with the idea of mimicking biologically active organo-selenium compounds3.4. Over a period, several groups have designed and synthesized numerous organoselenium compounds with the aim to emulate the activity of naturally occurring selenoenzyme, GPx. Accordingly, different groups have studied several families of GPX active organoselenium compounds. These compounds can readily be recognized by one of the following features, (i) compounds containing a covalent Se - N bond (e.g. I - IV), (ii) compounds exhibiting weak intramolecular Se---N or Se---O interactions (e.g. V-VIII), (iii) heterocyclic diselenides, e.g. 2-pyridyl diselenide (IX) and (iv) compounds, both mono and diselenides, derived from alky groups bearing -OH, -NH,, -COOH substituent at terminal positions (X - XIII) (Scheme 2).
All the compounds have been purified by recrystallization or column chromatography and thoroughly characterized by elemental analysis, IR, NMR (+H, 13C{'H} and 77Se{H}) and mass spectral data. The 77Se NMR chemical shifts are distinctly different for monoselenides and diselenides, the latter being more deshielded relative to the corresponding monoselenide. Molecular structures of several compounds have been established by single crystal X-ray diffraction analyses (Figs 1-3). In some compounds weak intra- or inter-molecular secondary Se...X interactions exists while others are devoid of such interactions. For instance, compound (2-NC H (3-CONHPh)Se], (Fig. 3) represents the first example where two intra-molecular Se---X (X = N or O) secondary interactions exist in a diselenide (Se1'-- -N1 (2.887 Å) and Se1---01 (2.608 Å)]. Each selenium atom in the molecule is weakly coordinated to the oxygen atom of the carbonyl group of the same pyridyl ring with which it is bonded and also to the nitrogen atom of the other pyridyl ring.?
(1) ebelen
(V)
-ILM
,
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(VI) Singh
(VID) Wirth
VIII lain"
(Hot
(EX) Jacob er af"
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(XT) Juin and Priradarsini
(XII) Back tol?
(XIII) waoka et al."
(Scheme 2).
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Fig. 1. Molecular structure of (SeCH COOH),
Results and discussion: In the above perspective, our group has focused to develop low-molecular weight water-soluble organoselenium compounds which can show antioxidant and radio-protection properties. Accordingly we have synthesized different families of organoselenium compounds both new as well as reported earlier 5-7 To enhance water solubility of these compounds, molecules containing -OH, -COOH and NH, functionalities have also been prepared. The following four different classes of compounds have been synthesized by using M, Se, (M = Li or Na) or Na, Se with an appropriate halogenated organic compound. The compounds with OH/ COOH/NH, functional groups have been isolated by the reaction between RSeNa and X(CH)ny (n = 1-3; X = Cl or Br; Y = OH, NH, or COOH).
Fig. 2- Molecular structure of dmpzCH SECH, CH, OH
(Hydrogen atoms are omitted for clarity)
(i) Seleno ethers: (HOOC-CH,),Se; (HOOC
CH,CH,),Se; (HOOC-CH2CH2CH2)Se; (HOCH,CH),Se; (HO-CH,CH,CH,),Se; (H2NCH,CH),Se; (H2N-CH,CH,CH),Se
Fig. 3- Molecular structure of (2-NCH,(3-CONHPh)Se),
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