Reductive Cleavage of the Se-Se Bond by the Sm-Me3SiCl-H2O System: Preparation of Unsymmetrical Phenyl Selenides

Article abstract of DOI:10.1039/a803305f

The reduction of diphenyl diselenide by the Sm-Me₃SiCl-H₂O system led to a selenide anion. This 'living' species reacted with organic halides, epoxides, α,β-unsaturated esters and α,β-unsaturated nitrtles to afford unsymmetrical phenylselenides in good yields under mild and neutral conditions.

Full text of DOI:10.1039/a803305f

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598 J. CHEM. RESEARCH (S), 1998
J. Chem. Research (S),
1998, 598±599$
Reductive Cleavage of the Se±Se Bond by the
Sm±Me3SiCl±H2O System: Preparation of
Unsymmetrical Phenyl Selenides$
Lei Wang and Yongmin Zhang*
Department of Chemistry, Hangzhou University, Hangzhou, 310028, PR China
The reduction of diphenyl diselenide by the Sm±Me3SiCl±H2O system led to a selenide anion. This `living' species
reacted with organic halides, epoxides, ꢀ,ꢁ-unsaturated esters and ꢀ,ꢁ-unsaturated nitriles to afford unsymmetrical
phenylselenides in good yields under mild and neutral conditions.
Organoselenium compounds have received considerable
attention as useful synthetic reagents and intermediates
in organic synthesis.1 While there are many methods for
the introduction of
a seleno-substituent into organic
molecules, the use of phenyl selenide anions is especially
convenient and common. Several methods for the synthesis
of selenide anions have been recommended, the more
important of which include the use of diphenyl diselenide
with sodium borohydride,2 reduction of the diselenide with
sodium,3 samarium diiodide4 and lithium aluminium
hydride.5 Alternatively, sodium phenyl selenide may be
obtained from the selenol using sodium hydride or even by
treatment with aqueous sodium hydroxide under certain
conditions.6 Moreover, Grignard reagents also react with
selenium to give selenide anions.7
Scheme 1
As a powerful, versatile and either-soluble one-electron
transfer reducing agent, SmI2 has been widely applied in
organic synthesis.8 Though SmI2 is a useful reagent, storage
is dicult because it is very sensitive to air oxidation. On
the other hand, metallic samarium is stable in air and its
strong reducing power (Sm3‡/Sm 2.41 V) is similar to that
of magnesium (Mg2‡/Mg 2.37 V) and superior to that of
zinc (Zn2‡/Zn 0.71 V). These properties prompted us to
use the more convenient and cheaper samarium directly as a
reductant instead of samarium(II) iodide. Recently, there
have been reports on the direct use of Sm in organic
synthesis.9 Ishii and co-workers have shown that the
Sm±Me3SiCl±NaI and Sm±Me3SiBr systems can be used for
the intermolecular carbon±carbon bond formation reaction
of carbonyl compounds.10 Herein, we report that the
Sm±Me3SiCl±H2O system promotes cleavage of the Se±Se
bond to form a phenyl selenide anion. This species reacted
with organic halides, epoxides, a,b-unsaturated esters and
a,b-unsaturated nitriles to a€ord unsymmetrical phenyl-
selenides in good yields under mild and neutral conditions.
The results are summarized in Table 1.
We found that under mild conditions, phenyl selenide
anion, readily prepared in situ from the cleavage of the
Se±Se bond of diphenyl diselenide with the Sm±Me3SiCl±
H2O reduction system, reacted easily with epoxides, a,b-
unsaturated esters and a,b-unsaturated nitrile respectively to
a€ord the desired unsymmetrical alkyl phenyl selenides in
good yields. From Table 1, we also found that the phenyl
selenide anion, a `living' species, reacted smoothly with
active organic halides such as 2-bromoacetophenone and
ethyl bromoacetate to give products in good yields at 45 8C.
Table 1 Preparation of unsymmetrical phenyl selenides via phenyl selenide anion intermediate
Coupling reaction
conditions
Entry
R1X
R2
R3
Z
T/8C
t/h
Yield (%)a
a
b
c
d
db
e
f
g
h
i
PhCH2Cl
65
45
45
65
65
65
65
65
45
45
45
45
45
4
3
3
4
4
10
4
4
2
2
75
72
66
68
32
Ð
70
72
80
82
79
84
83
PhCOCH2Br
BrCH2CO2Et
n-C4H9Br
n-C4H9Br
n-C4H9Cl
n-C6H13Br
n-C8H17Br
H
CH2Cl
j
k
l
H
H
Me
CN
CO2Me
CO2Me
2
2
2
aIsolated yields. Reaction conditions: diphenyl diselenide (0.5 mmol), Sm (1.0 mmol), Me3SiCl (1.0 ml), THF
(5 ml), H2O (18 ꢂl), cleavage reaction temperature, 45 8C, 3 h. bIn the absence of water.
*To receive any correspondence.
With the less active halides R2X such as alkyl bromides
and benzyl chloride, the coupling reaction should be carried
out at a higher temperature (65 8C). Unfortunately, alkyl
$This is a Short Paper as de®ned in the Instructions for Authors,
Section 5.0 [see J. Chem. Research (S), 1998, Issue 1]; there is there-
fore no corresponding material in J. Chem. Research (M).

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J. CHEM. RESEARCH (S), 1998 599
d, CH2Cl), 3.64±4.00 (1 H, m, CH), 7.03±7.49 (5 H, m, ArH).
chloride gives too little product to be isolated even with a
longer reaction time (entry e).
1
max/cm 3450, 2089, 3050, 2945, 2900, 1590, 1485, 1460, 1050,
ꢃ
1020, 940, 735, 700.
The result of our experiment indicated that as a small
amount of water was added to the Sm±Me3SiCl system,
it not only accelerated the cleavage reaction, but also
increased the yield of product. However, the mode of action
is not fully understood and a more detailed study is in
progress in our laboratory.
In conclusion, it has been found that the Sm±Me3SiCl±
H2O reductive system is an e€ective one for cleaving the
Se±Se bond in diphenyl diselenide at mild temperatures.
The notable advantages of this reaction are neutral reaction
conditions, simple operation and good yields.
b-(Phenylseleno)propionitrile.18 Oil. dH 2.30±2.70 (2 H, m,
CH2CN), 2.74±3.13 (2 H, m, CH2Se), 7.00±7.52 (5 H, m, ArH).
1
max/cm 3100, 3080, 2950, 2254, 1588, 1485, 1445, 1420, 1070,
ꢃ
1020, 932, 735, 685.
Methyl 3-(phenylseleno)propanate.15 Oil. dH 2.33±2.77 (2 H, m,
CH2CO2R), 2.80±3.18 (2 H, m, CH2Se), 3.50 (3 H, s, OCH3),
1
6.97±7.53 (5 H, m, ArH). ꢃmax/cm 3060, 2965, 1750, 1590, 1485,
1460, 1355, 1225, 1165, 1021, 935, 735, 690.
Methyl 2-methyl-3-(phenylseleno)propanate.19 Oil. dH 1.1±1.2
(3 H, d, CH3), 2.40±2.60 (2 H, m, CH), 2.65±3.20 (2 H, m, CH2Se),
1
3.54 (3 H, s, OCH3), 7.00±7.65 (5 H, m, ArH). ꢃmax /cm 3065,
2950, 1745, 1590, 1480, 1450, 1360, 1230, 1170, 930, 730, 690.
We thank the National Natural Science Foundation
of China (Grant no. 29672007) and the Laboratory of
Organometallic Chemistry, Shanghai Institute of Organic
Chemistry, and the Chinese Academy of Sciences for
®nancial supports.
Experimental
1H NMR spectra were recorded on a JEOL PMX 60 SI instru-
ment. All NMR samples were measured in CCl4 using Me4Si as
internal standard. IR spectra were obtained on a Perkin-Elmer 683
spectrophotometer as liquid ®lms.
Metallic samarium and other chemicals were purchased from
commercial sources and used without puri®cation. Chlorotri-
methylsilane was redistilled prior to use and kept under an inert
atmosphere with molecular sieves. THF was freshly distilled from
sodium±benzophenone ketyl prior to use.
Received, 1st May 1998; Accepted, 28th May 1998
Paper E/8/03305F
General Procedure for the Preparation of Unsymmetrical Phenyl
Selenides.ÐUnder
References
a nitrogen atmosphere, metallic samarium
powder (0.15 g, 1.0 mmol) and diephenyl diselenide (0.16 g,
0.5 mmol) were placed in a three-necked reaction ¯ask and Me3SiCl
(1.0 ml) and THF (5 ml) were added in one portion. Then H2O
(18 ꢂl) was added to the mixture and the resulting mixture was
magnetically stirred for 3 h at 45 8C until the powdered samarium
was almost consumed and the yellow solution had become almost
colorless. To the mixture was added organic halide (1.2 mmol), (or
epoxides, etc.) in THF (5 ml). When the reaction was complete,
water (4 ml) was added to quench the reaction and the mixture was
extracted with diethyl ether (2 Â 20 ml). The extracts were washed
with brine, dried over anhydrous Na2SO4 and the solvent was
removed under reduced pressure; the residue was then puri®ed by
preparative TLC on silica gel to give pure product.
1 The Chemistry of Organic Selenium and Tellurium Compounds,
ed. S. Patai and Z. Rappoport, John Wiley, Chichester, 1986,
vol. 1.
2 K. B. Sharpless and R. F. Laura, J. Am. Chem. Soc., 1973, 95,
2697.
3 E. E. Aynsley, N. N. Greenwood and J. B. Leach, Chem. Ind.,
1966, 379.
4 Y. Zhang, Y. Yu and R. Lin, Synth Commun., 1993, 23, 189.
5 H. Suzuki, M. Yoshinaga, K. Takaoka and Y. Hiroi, Synthesis,
1985, 497.
6 D. Liotta, U. Sunay, H. Santiesteban and W. Markiewicz,
J. Org. Chem., 1981, 46, 2605; D. L. Klayman and W. H. H.
Gunther, Organic Selenium Compounds: Their Chemistry and
Biology, John Wiley, New York, 1973, p. 191.
7 F. Taboury, Bull. Soc. Chim. Fr., 1903, 29, 761.
8 H. B. Kagan and J. L. Namy, Tetrahedron, 1986, 42, 6573;
G. A. Molander, Chem. Rev., 1992, 92, 29; G. A. Molander,
Org. React., 1994, 46, 211; G. A. Molander and C. R. Harris,
Chem. Rev., 1996, 96, 307.
9 R. Yanada, N. Negoro, K. Yanada and T. Fujita, Tetrahedron
Lett., 1997, 38, 3271 and references cited therein.
10 N. Akane, Y. Kanagawa, Y. Nishiyama and Y. Ishii, Chem.
Lett., 1992, 2431; N. Akane, T. Hatano, H. Kusui, Y. Nishiyama
and Y. Ishii, J. Org. Chem., 1994, 59, 7902.
Benzyl phenyl selenide.11 Oil. dH 3.95 (2 H, s, CH2Se), 7.05±7.45
1
(10 H, m, ArH). ꢃmax/cm 3090, 2980, 1580, 1490, 1440, 1150, 940,
740, 690.
2-(Phenylseleno)acetophenone.4 Oil. dH 4.05 (2 H, s, CH2Se),
1
7.00±7.95 (10 H, m, ArH). ꢃmax/cm 3085, 2960, 1682, 1600, 1590,
1480, 1410, 1275, 1180, 925, 735, 700, 680.
Ethyl 2-(phenylseleno)acetate.12 Oil. dH 1.12 (3 H, t, CH3), 3.29
(2 H, s, CH2Se), 3.96 (2 H, q, OCH2), 7.01±7.65 (5 H, m, ArH).
1
max/cm 3070, 2960, 1750, 1590, 1485, 1460, 1350, 1220, 1170,
ꢃ
935, 740, 690.
Butyl phenyl selenide.13 Oil. dH 0.80 (3 H, t, CH3), 1.00±1.85
[3 H, m, (CH2)2], 2.70 (2 H, t, CH2Se), 6.95±7.55 (5 H, m, ArH).
11 V. F. Patel, G. Pattenden and D. M. Thompson, J. Chem. Soc.,
Perkin Trans. 1, 1990, 2729.
1
max/cm 3050, 2950, 1590, 1470, 1420, 1370, 1220, 1115, 920, 735,
ꢃ
700.
Hexyl phenyl selenide.14 Oil. dH 0.80 (3 H, t, CH3), 1.00±1.95
[8 H, m, (CH2)4], 2.95 (2 H, t, CH2Se), 7.00±7.60 (5 H, m, ArH).
12 K. Haraguchi, H. Tanaka and T. Miyasaka, Tetrahedron Lett.,
1990, 31, 227.
13 R. Raucher and G. A. Koolpe, J. Org. Chem., 1978, 43, 4252.
14 G. A. Russell, P. Ngoviwatchai, H. I. Tashtoush, A. Pla-
Dalmau and R. K. Khanna, J. Am. Chem. Soc., 1988, 110,
3530.
15 S. V. Ley, I. A. O'Neil and C. M. R. Low, Tetrahedron, 1986,
42, 5363.
16 P. Rollin, V. V. Bencomo and P. Sinay, Synthesis, 1984, 134.
17 L. A. Khazemova and V. M. Al'bitskaya, Zh. Org. Khim., 1969,
5, 1926.
1
ꢃ
max/cm 3040, 2940, 1580, 1480, 1420, 1380, 1230, 1100, 930, 740,
690.
Octyl phenyl selenide.15 Oil. dH 0.80 (3 H, t, CH3), 1.00±2.10
[12 H, m, (CH2)6], 3.20 (2 H, t, CH2Se), 7.02±7.70 (5 H, m, ArH).
1
ꢃmax/cm 3020, 2945, 2860, 1589, 1460, 1400, 1220, 1110, 1041,
928, 790, 740, 690.
2-(Phenylseleno)ethanol.16 Oil. dH 2.34 (1 H, s, OH, disappeared
on adding D2O), 2.90 (2 H, t, CH2Se), 3.59 (2 H, t, CH2O),
1
7.00±7.54 (5 H, m, ArH). ꢃmax/cm 3530, 3040, 2955, 2900, 1600,
1490, 1462, 925, 740, 700.
18 A. Ogawa, Y. Nishiyama, N. Kambe, S. Murai and N. Sonoda,
Tetrahedron Lett., 1987, 28, 3271.
19 E. G. Kataev and F. G. Gabdrakhmanav, Zh. Obshch. Khim.,
1967, 37, 772.
1-Chloro-3-(phenylseleno)propan-2-ol.17 Oil. dH 2.73 (1 H, s, OH,
disappeared on adding D2O), 3.00 (2 H, d, CH2Se), 3.52 (2 H,