(102 mbar) from the reaction mixture. A cold trap (260 °C) removed
selectively the less volatile products and compounds 3a–c, 4a–c were
condensed on a cold finger (2196 °C) connected at the bottom to a flask or
an NMR tube. A co-solvent can be added at this step. After disconnecting
from the vacuum line by stopcocks, the apparatus was filled with dry
nitrogen; liquid nitrogen was subsequently removed. The product was
collected in a Schlenk flask or a NMR tube and kept at low temperature
1
Table 1 Yield and selected NMR data for the ethyl and ethenyl selenium
and tellurium derivatives
(
‡
< 250 °C) before analysis.
Under these experimental conditions, we have also prepared alkylthiols
(EtSH, yield: 96%), vinylthiols (MeCHNCHSH, yield: 91%), arylthiols
(PhSH, yield: 77%), alkylselenols (EtSeH, yield: 89%) and alkyltellurols
(EtTeH, yield: 83%). The reaction with EtSeSEt led to ethanethiol (yield:
9
2%) and traces of EtSeH suggesting that the ethylseleno group acts as a
protecting group for the thiol.
Selected data: 3b,bA: bp (0.1 Torr) ≈ 270 °C. Yield: 83%. t1/2 (5% in
CDCl ) ≈ 25 h. (E)-3b: d (400 MHz, CDCl , 240 °C) 0.78 [d, 1H, J 5.3,
SeH 60.7 Hz (d), SeH], 1.72 (d, 3H, J 6.4 Hz, CH ), 5.98 (dq, 1H, J 15.3,
.4 Hz, CH), 6.10 (m, 1H, CH). d (100 MHz, CDCl , 240 °C) 20.2, 107.4,
33.7. dSe(57.2 MHz, CDCl , 240 °C) 31.0. (Z)-3bA. d (400 MHz, CDCl
40 °C) 0.69 (d, 1H, J 6.9 Hz, SeH), 1.67 (d, 3H, J 6.6 Hz, CH ); 6.04 (dq,
H, J 8.7, 6.6 Hz, CH), 6.31 (dd, 1H, J 8.7, 6.9 Hz, CH). d (100 MHz,
CDCl , 240 °C) 16.0, 110.6, 128.4. dSe (57.2 MHz, CDCl , 240 °C) 75.4.
HRMS: calc. for (C Se·) (Z + E): m/z 121.9634; found: 121.963. 3c:
bp (0.1 Torr) ≈ 260 °C. Yield: 77%. t1/2 (5% in CDCl ) ≈ 20 h. d (400
, 240 °C) 0.61 [d, 1H, J 5.9, JSeH 60.5 Hz (d), SeH]; 1.72 (s,
), 1.80 (s, 3H, CH ), 5.95 (d, 1H, J 5.9 Hz, CH). d (100 MHz,
, 240 °C) 20.9, 26.0, 101.8, 138.3. dSe(57.2 MHz, CDCl , 240 °C)
Se·) : m/z 135.9791; found: 135.979. 4b: bp
): 1 h. d (400 MHz,
§
3
H
3
1
J
3
6
1
2
1
C
3
3
H
3
,
3
C
3
3
80
+
3 6
H
3
H
1
MHz, CDCl
H, CH
CDCl
4 8
6.0. HRMS calc. for (C H
3
(
4
32–43%) were observed for the more reactive tellurols
a–c.‡
3
3
3
C
3
3
All compounds 3a–c, 4a–c were unambiguously charac-
8
0
+
2
terized by 1H, C, Se or
13
77
125
Te NMR spectroscopy and
(0.1 Torr) ≈ 250 °C. Yield: 43%. t1/2 (5% in CDCl
3
H
1
HRMS.§ In the H NMR spectrum, the presence of an
unsaturated group on a heteroatom usually leads to a downfield
shift of the signals of hydrogen(s) attached to the heteroatom
1
CDCl , 240 °C) 23.43 [d, 1H, J 5.4, JTeH 26.2 Hz (d), TeH], 1.71 (d, 3H,
3
J 6.3 Hz, CH ), 6.33 (dq, 1H, J 9.0, 6.3 Hz, CH), 6.61 (dd, 1H, J 9.0, 5.4 Hz,
3
CH). dC (100 MHz, CDCl , 240 °C) 20.6, 94.5, 136.0. dTe(94.7 MHz,
3
and an increase in the coupling constants.9 In the H NMR
spectra of selenols 3a–c, the signal of the hydrogen on the
selenium atom was observed ca. 1.5 ppm downfield to that of
the saturated derivative (Table 1). A similar downfield effect
,11
1
130
+
CDCl
3
, 240 °C) 295.4. HRMS: calc. for (C
H
3 5
Te.) : m/z 171.9539;
found: 171.953. 4c: bp (0.1 Torr) ≈ 250 °C. Yield: 34%. t1/2 (5% in
1
CDCl
3
): 1 h. d
H
(400 MHz, CDCl
3
, 240 °C) 22.78 [s, 1H, JTeH 28.5 Hz
); 5.40 (q, 1H, J 1.3 Hz, HCH); 5.75 (q,
(100 MHz, CDCl , 240 °C) 34.1, 116.3, 125.6. dTe
, 240 °C) 182.5. HRMS: calc. for (C
71.9539; found: 171.954.
(d), TeH], 2.34 (t, 3H, J 1.3 Hz, CH
3
1
H, J 1.3, HCH). d
C
3
1
1
was observed for the tellurols. The JSeH and JSeC coupling
constants of the unsaturated compounds 3a–c are higher than
128
+
(94.7 MHz, CDCl
3
3
H
6
Te·) : m/z
1
1
1
those of the saturated compounds [ JSeC (3a): 93.2 Hz, JSeC
EtSeH): 45.0 Hz]. This can be attributed to an increase of the
s character of the Se–H and Se–C bonds. Although a similar
(
1
A. J. Kresge, Acc. Chem. Res., 1990, 23, 43; B. J. Smith and L. Radom,
J. Am. Chem. Soc., 1989, 111, 8297.
1
increase was observed for the
tellurols [ JTeC (4a): 247.3 Hz, JTeC (EtTeH): 114.9 Hz], an
opposite effect was observed for the JTeH coupling constants.
To the best of our knowledge although a upfield signal has been
observed for the proton on the mercury atom of the vinyl
derivative,12 such a decrease of a JXH coupling constant for a
vinylic derivative has never been reported.
Vinylselenols and vinyltellurols exhibit a low stability at
room temperature: the half-life of selenols 3a–c diluted in
J
TeC coupling constant of
2 O. Mó, M. Yáñez, M. Decouzon, J.-F. Gal, P.-C. Maria and J.-C.
Guillemin, J. Am. Chem. Soc., 1999, 121, 4653.
3 L. Lassalle, S. Legoupy and J.-C. Guillemin, Organometallics, 1996,
1
1
1
1
5, 3466; J.-C. Guillemin, L. Lassalle, P. Dréan, G. Wlodarczak and J.
Demaison, J. Am. Chem. Soc., 1994, 116, 8930.
4
5
A. Chrostowska, V. Métail, G. Pfister-Guillouzo and J.-C. Guillemin,
J. Organomet. Chem., 1998, 570, 175 and references therein.
Ethynylselenol has been detected by IR spectroscopy among other
products in an argon matrix at 8 K: J. Laureni, A. Krantz and R. A.
Hajdu, J. Am. Chem. Soc., 1976, 98, 7872.
1
CDCl
3
is ca. one day and ca. 60 min for the tellurols 4a–c. Only
6 Y. Vallée, M. Khalid, J.-L. Ripoll and A. Hakiki, Synth. Commun.,
1993, 23, 1267.
7 H. C. Brown, P. B. Weissman and N. M. Yoon, J. Am. Chem. Soc., 1966,
insoluble black decomposition products were observed after a
few days.
In conclusion, we have successfully prepared vinylselenols
8
8, 1458; C. F. Allen and D. D. MacKay, Org. Synth., 1943, Coll. Vol.
II, 580; L. E. Overman, J. Smoot and J. D. Overman, Synthesis, 1974,
9.
and tellurols by reaction of Bu
3
SnH with the corresponding
5
diselenide or ditelluride derivatives. By reaction with a hydride
8
9
L. Brandsma, Recl. Trav. Chim. Pays-Bas, 1970, 89, 593.
J.-C. Guillemin and K. Malagu, Organometallics, 1999, 18, 5259.
n
(
3
Bu SnH), compounds bearing an acidic hydrogen (RSH,
RSeH, RTeH) were prepared via a radical reaction thus
providing a new route which is an alternative to the hydrolytic
method. Further investigation into the synthesis of other
unsaturated selenols and tellurols, and spectroscopic studies are
currently under progress in our lab.
We thank the PNP (INSU-CNRS) and the CNES for financial
support and Dr M. Davies for helpful suggestions in writing the
paper.
1
0 S. Legoupy, L. Lassalle, J.-C. Guillemin, V. Metail, A. Senio and G.
Pfister-Guillouzo, Inorg. Chem., 1995, 35, 1466.
11 L. Lassalle, T. Janati and J.-C. Guillemin, J. Chem. Soc., Chem.
Commun., 1995, 699.
12 J.-C. Guillemin, N. Bellec, S. Kiz-Szétsi, L. Nyulászi and T. Veszprémi,
Inorg. Chem., 1996, 35, 6586.
1
1
1
3 D. Crich, J.-T. Hwang, S. Gastaldi, F. Recupero and D. J. Wink, J. Org.
Chem., 1999, 64, 2877.
4 M. J. Dabdoub and J. V. Comasseto, J. Organomet. Chem., 1988, 344,
1
67.
5 For 77Se NMR data, see: H. Duddeck, Prog. NMR Spectrosc., 1995, 27,
Notes and references
1
.
†
Typical experimental procedure: (CAUTION: Selenols and tellurols are
16 L. Brandsma and H. E. Wijers, Recl. Trav. Chim. Pays-Bas, 1963, 82,
potentially highly toxic compounds and must be used with great care under
68.
a well-ventilated hood). The apparatus already described for the reduction
of dichlorostibines was used. The flask containing the precursor [2 mmol
17 A. Baroni, Atti Accad. Naz. Lincei Cl. Sci. Fis. Mater. Nat. Rend., 1938,
6, 238.
10
of 1a–c or 2a–c diluted in tetraglyme (5 mL)] was fitted on a vacuum line
18 H. C. E. McFarlane and W. McFarlane, NMR Newly Accessible Nucl.,
1983, 2, 275.
n
and degassed. Bu
3
SnH (3 mmol) was then slowly added (30 min) at room
temperature with a syringe through the septum. During and after the
addition, vinylselenols 3a–c or tellurols 4a–c was distilled off in vacuo
19 H. E. Wijers, H. Boelens, A. Van der Gen and L. Brandsma, Recl. Tav.
Chim. Pays-Bas, 1969, 88, 519.
1164
Chem. Commun., 2000, 1163–1164