Angewandte
Chemie
second radical species : g = 2.005 (quintet of triplets, a(N) = 15.2 G
mass spectrum of d-selenooxime 7 is analogous to that the
sulfur compound 6. NMR spectra (complete assignment
(1N), a(Hb) = 10.5 G (4H)).
1
77Se NMR (C6D6) after decomposition of 4b: d = 635 (4d), 552
through 2D H/13C experiments) indicate that 7 is a mixture
1
(4d), 482, 396 (4a), 332 ppm; H NMR (C6D6): d = 0.37, 0.32, 0.29,
of isomers (E/Z ca. 1:1) composition.
0.13 ppm; IR (KBr): n˜ = 1259 (st), 1098 (s), 1014 (s), 849 (st), 678 (s),
In summary, nitrosation of selenols 2a, and 4a occurs
significantly faster than that of the related thiols 1a and 3a.
The nitrosated selenium species are thermally much less
stable than the related S-nitrosothiols and release NO much
more readily.[22] We expect that the reaction sequence selenol
651 (2), 602 cmꢀ1(s).
6: A mixture of 3b (1.1 g, 3.8 mmol) and 2,3-dimethylbuta-1,3-
diene (2 mL) was stirred for 3 d. The volatiles were removed to give a
yellow oil. On addition of n-pentane a colorless solid (1 g, 72%)
separated, which was recrystallized from n-pentane (m.p. 1458C
(decomp)). 1H NMR (C6D6): d = 0.24 (s, SiCH3), 1.67 (s, CH3), 2.10 (s,
CH3), 3.30 (s, CH2), 8.08 (br s, OH), 8.24 ppm (s, CH); 13C NMR
(C6D6): d = 2.78 (SiCH3), 11.44 (s, Si3CS), 13.68 (s, CH3), 18.10 (s,
CH3), 39.15 (s, CH2), 136 (s, q), 149.80 ppm (s, CH); MS(CI/
isobutane): m/z = 376 [M+H]+.
ꢀ
nitrosation followed by Se NO homolysis will give instigate
further studies on the possible interactions of selenoproteins[4]
with nitrosation agents.[1–3,22]
7: To a solution of 4a (1.2 g, 3.8 mmol) in n-pentane (10 mL) at
ꢀ788C was added tert-butylnitrite (1.3 mL, 38 mmol). After 5 min
2,3-dimethylbuta-1,3-diene (1 mL) was added to the red solution. The
solution was stirred at ꢀ508C for 5 d and then warmed to room
temperature. Removal of all volatiles gave a red oil, to which n-
pentane (5 mL) was added. An insoluble white solid was removed and
the pentane-soluble fraction subjected to column chromatography
(SiO2, pentane/ethylacetate 95:5). 13C NMR spectra indicate that the
second fraction contained 7 (a few mg).
Experimental Section
1b: To a solution of 1a (0.3 g, 1.46 mmol) in n-pentane (5 mL) was
added tert-butylnitrite (1.5 mL, 14.6 mmol) at ꢀ208C. In the
13C NMR spectrum all signals except that of a quarternary C atom
(which was covered by a solvent peak) were observed. IR and UV
1
data were obtained from the reaction mixture. 1b: H NMR (C6D6):
d = 1.19 (s, CH3), 3.63 (s, OCH2); 6.84–6.79 (m, 2HAr), 7.94–8.00 ppm
(m, 2HAr), 13C NMR (C6D6): d = 28.5 (s, CCH3), 69.0 (s, CCH3), 78.4
(s, OCH2), 125.3 (s, CH), 126.2 (s, CH), 126.4 (s, q), 130.1 (s, CH),
Important NMR data of 7 in C6D6: (E)-oxime: 1H NMR: d =
1
8.20 ppm (s, 1H, N CH); 13C NMR: d = 149.9 ppm (CH, J(C, H) =
=
=
1
131.3 (s, CH), 160.5 ppm (s, C N); UV/Vis (n-pentane, 208C) l (lge):
=
=
163 Hz, N CH); (Z)-oxime: H NMR: d = 8.51 ppm (s, 1H, N CH);
C NMR: d = 149.8 ppm (CH, J(C, H) = 161 Hz, N CH). 77Se NMR:
13
1
218 (2.89), 304 (2.28); IR (film, n-pentane): n˜ = 1648 (st), 1467 (m),
1364 (m), 1353 (m), 1314 (m), 1189 (m,), 1135 (m), 1080 (m), 1042 (m),
1033 (st), 965 (st), 770 (m), 736 (m), 698 (m), 683 (m), 651 cmꢀ1 (m).
2b: tert-Butylnitrite (0.11 mL, 1.06 mmol) was added to a solution
of 2a (0.27, 1.06 mmol) in THF (5 mL) at ꢀ788C, and the solution
turned deep red instantaneously. 77Se NMR measurements at ꢀ788C
were unsuccessful. At room temperature, the signal of diselenide
2c[11a] was detected. 77Se NMR (THF/[D8]THF): d = 434 [ref. [11a]:
d = 454.8 (CDCl3)]. In order to record EPR spectra the reaction was
carried out in n-pentane and the spectra of the reaction mixture were
measure at room temperature immediately. EPR (n-pentane): g =
2.005, a(N) = 15.4 G (1N), a(Hb) = 10.1 G (4H, the same quintet-of-
triplets pattern as that for the secondary radical obtained by
nitrosation of 4a).
3b: A solution of the freshly sublimed thiol 3a (1 g, 3.79 mmol) in
n-pentane (5 mL) at room temperature was treated with tert-
butylnitrite (0.64 mL, 35.87 mmol). The resulting red–green solution
was stirred for 30 min, and subsequently all volatiles were removed
under reduced pressure to furnish 3b as green solid (0.99 g, 89%),
m.p. 81–828C. 1H NMR (C6D6): d = 0.14 ppm (s, CH3); 13C NMR
(C6D6): d = 1.5 [Si((CH3)3)], 3.4 ppm (CSi3); 29Si{1H} NMR (C6D6):
d = 3.1 ppm; MS(CI/isobutane): m/z = 294 [M+H]+; UV/Vis (n-
pentane, 208C) l (lge): 210 (3.74); 236 (3.41); 264 (3.00); 364 (2.84);
564 (1.14); 608 (1.09). IR (KBr): n˜ = 612 (st), 621 (st), 652 (m), 677
(m), 720 (m), 803 (m), 821 (m), 853 (m), 1021 (m), 1098 (m), 1261 (m),
1412 (st), 2902 (m), 2961 cmꢀ1 (m). Elemental analysis (%) calcd for
C10H27NOSSi3 (293): C 40.96, H 9.22, N 4.78, S10.92; found: C 40.83,
H 8.94, N 4.26, S10.67.
=
d = 223, 240 ppm. MS(CI/isobutane): m/z = 424 [M+H]+.
Received: January 28, 2004
Revised: May 6, 2004 [Z53872]
Keywords: bioinorganic chemistry · nitrogen oxides ·
.
nitrosation · oximes · selenium
[1] a) F. Murad, Angew. Chem. 1999, 111, 1976 – 1989; Angew.
Chem. Int. Ed. 1999, 38, 1856 – 1868; b) L. J. Ignarro, Angew.
Chem. 1999, 111, 2003 – 2013; Angew. Chem. Int. Ed. 1999, 38,
1882 – 1892.
[2] a) D. L. H. Williams, Chem. Commun. 1996, 1085 – 1091;
b) D. L. H. Williams, Acc. Chem. Res. 1999, 32, 869 – 876; c) N.
Arulsamy, D. S. Bohle, J. A. Butt, J. Irvine, P. A. Jordan, E. J.
Sagan, J. Am. Chem. Soc. 1999, 121, 7115 – 7123; d) A. A.
Romeo, J. A. Capobianco, A. M. English, J. Am. Chem. Soc.
2003, 125, 14370 – 14378; e) H. Al-SaꢀDoni, A. Ferro, Clin. Sci.
2000, 98, 507 – 520; f) D. Vorländer, E. Mittag, Ber. Dtsch. Chem.
Ges. 1919, 52, 413 – 423.
[3] K. Wang, W. Zhang, M. Xian, Y.-C. Hou, X.-C. Chen, J.-P.
Cheng, P. G. Wang, Curr. Med. Chem. 2000, 7, 821.
[4] H. Sies, L. Packer, Methods Enzymol. 2002, 347, 121 – 125.
[5] a) H. Sies, V. S. Sharov, L.-O. Klotz, K. Briviba, J. Biol. Chem.
1997, 272, 27812 – 27817; b) H. Sies, G. E. Arteel, Free Radical
Biol. Med. 2000, 28, 1451 – 1455.
[6] M. Asahi, J. Fujii, T. Takao, T. Kuzuya, M. Hori, Y. Shimonishi,
N. Taniguchi, J. Biol. Chem. 1997, 272, 19152 – 19157.
[7] J. E. Freedman, B. Frei, G. N. Welch, J. Loscalzo, Am. Soc. Clin.
Inv. 1995, 96, 394 – 400.
4b: tBuONO (0.29 mL, 2.0 mmol) was added to a solution of
selenol 4a (0.62 g, 2.0 mmol) in n-pentane (5 mL) at ꢀ788C. The
solution turned red immediately. No signals could be detected by 77Se
NMR spectroscopy. Removal of the volatiles after 30 min gave a red
oil. IR: n˜ = 1621 (s), 1459 (st), 1368 (st), 1255 (st), 1099 (m), 1024 (m),
954 (s), 836 (st), 680 (m), 615 cmꢀ1 (s).
MS: The reaction mixture was transferred into an argon-filled
headspace tube. The sample was kept at room temperature for 1 h
before a gaseous sample was removed. GC/MS[ m/z = 28 (100), 30
(45), 32 (15)] indicated NO accompanied by some air.
EPR (n-pentane): The reaction mixture was transferred into an
EPR tube at room temperature under N2. First radical species 5: g =
2.011 (quintet, simulation with a(N) = 7.6 G (2N) and a(Se) = 30 G);
[8] D. Nikitovic, A. Holmgren, J. Biol. Chem. 1996, 271, 19180 –
19185.
[9] GSNO can also be substrate of selenium-free Trx systems: S. M.
Kanzok, S. Rahlfs, K. Becker, R. H. Schirmer, Methods Enzy-
mol. 2002, 347, 370 – 381.
[10] Y. C. Hou, Z. M. Guo, J. Li, X. Zhu, Z. Yin, P. G. Wang,
Biochem. Biophys. Res. Commun. 1996, 228, 88 – 93.
Angew. Chem. Int. Ed. 2004, 43, 3970 –3974
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3973