150 J. CHEM. RESEARCH (S), 1998
J. Chem. Research (S),
1998, 150±151$
A Novel Synthesis of Allyl and Prop-2-ynyl Selenides
Promoted by Tin in the Presence of Water$
Puhong Liao, Weiliang Bao and Yongmin Zhang*
Department of Chemistry, Hangzhou University, Hangzhou, 310028, P.R. China
Allylic and prop-2-ynyl (propargyl) bromides react with diorganyl diselenides in the presence of water to give allylic and
prop-2-ynyl selenides in moderate to good yields; the reaction rate is faster than for the same reaction in anhydrous or-
ganic media.
Metal-mediated reactions in aqueous media have recently
found considerable applications in organic synthesis.1,2
Such aqueous organometallic reactions oer a number of
advantages over conventional organometallic reactions,
including their simple operation through obviating the need
for anhydrous organic solvents and an inert atmosphere,
and there is no need to protect `reactive' hydroxy functional
groups etc. Although tin has been one of the most
commonly used metals in aqueous organometallic reactions,
tin-mediated reactions in aqueous media have only focused
on the allylation reaction of carbonyl compounds, crossed
aldol and Reformastasky-type reactions.1a It is expected that
the scope of the reactions will be extended.
selenide anions,4 dehydroxysilylation of 2-hydroxy-3-
trimethylsilypropylselenide catalysed by SnCl2,5 and the
reaction of allylic acetates with diphenyl diselenide induced
by samarium diiodide in the presence of a palladium
catalyst.3 Some of the methods suer from disadvantages,
e.g. a strong base (EtONa) and poisonous starting material
(PhSeH) were used.4 Here we provide a very simple and
easy alternative method for the synthesis of allylic and
prop-2-ynyl selenides in moderate to good yields.
As can be seen from Table 1, when the reaction takes
place in the presence of water it is faster than the same
reaction in anhydrous organic media (entries 1, 2 and 3).
Compared with the dialkyl diselenide, diphenyl diselenide is
more suitable as a substrate (entries 5 and 6).
We report here a novel synthesis of allyl and prop-2-ynyl
(propargyl) selenides via reactions, promoted by tin, of
allyl and pro-2-ynyl bromides with diselenides in aqueous
media.
Experimental
1H NMR spectra were recorded in CCl4 on a JEOL PMX 60si
spectrometer using TMS as internal standard. IR spectra were
obtained on a Perkin Elmer 683 spectrometer.
General Procedure.ÐIn a 50 ml three-necked ¯ask ®tted with
a re¯ux condenser and a magnetic stirrer were placed 1.5 mmol
metallic tin powder, 1.5 mmol diorganyl diselenide, 4 mmol allylic
bromide and the solvent (as listed in Table 1). The mixture is stirred
vigorously at a speci®ed temperature for a given time, until the
powdered tin is almost consumed. The mixture is extracted with
diethyl ether twice (30 ml 2). The extracts are washed with brine,
dried (Na2SO4) and concentrated in vacuo. The product is obtained
from the residue through preparative TLC (silica gel) with light
petroleum (bp 30-60 8C)±diethyl ether as eluent.
Allylic selenides are useful intermediates in organic
synthesis. In allylic selenides, the allylic anions are stabilized
by the seleno group and can be attacked by nucleophiles
regioselectively.3 Allylic selenides can be prepared by several
methods, e.g. by the displacement of allylic halide by
Allyl phenyl selenide (1).ÐOil5; ꢀmax/cm 1, 3090, 3075, 2940,
1645, 1590, 1485, 1445, 1075, 1065, 1020, 1000, 985, 730, 685;
Table 1 Reaction conditions and yields
Entry
Products
Solventsa
Temp. (T/ 8C)
Time (t/h)
Yield (%)
15
PhSeCH2CH1CH2
A
B
A
B
A
B
50
50
50
50
65
50
24
12
30
20
30
24
75
80
73
78
70
74
26
36
p-CH3C6H4SeCH2CH1CH2
p-ClC6H4SeCH2CH1CH2
47
53
B
B
60
50
24
20
55
72
67
77
B
B
60
60
24
24
43
45
CH3(CH2)5SeCH2CH1CH2
aSolvent A is THF (20 ml) and solvent B is THF±H2O(20 ml 1 ml).
*To receive any correspondence.
ꢁH 3.32 (2 H, d, J 7 Hz), 4.65±4.92 (2 H, m), 5.45±6.15 (1 H, m),
7.06±7.58 (5 H, m).
$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).
Butyl cyclohex-2-enyl selenide (4).ÐOil7; ꢀmax/cm 1, 3045, 2980,
2950, 2880, 1650, 1590, 1450, 1382, 1260, 1180, 1000, 985, 862, 730;
Liao, Puhong
