A tin hydride designed to facilitate removal of tin species from products of stannane-mediated radical reactions

Article abstract of DOI:10.1021/jo010885c

The stannane 1, which is simple to prepare, behaves like the conventional reagents Bu₃SnH and Ph₃SnH in standard free radical reactions, but with the special characteristic that the tin-containing byproducts are easily and very largely removed by mild hydrolysis (LiOH-water-THF or TsOH-water-THF), which converts them into base-soluble (aqueous NaHCO₃) materials. The performance of stannane 1 was evaluated for a range of radical reactions involving halides, selenides, Barton-McCombie deoxygenation, and enyne cyclization. In several cases the effectiveness of the workup procedure in removing tin species was monitored by ¹H NMR.

Full text of DOI:10.1021/jo010885c

1192
J . Org. Chem. 2002, 67, 1192-1198
A Tin Hyd r id e Design ed To F a cilita te Rem ova l of Tin Sp ecies
fr om P r od u cts of Sta n n a n e-Med ia ted Ra d ica l Rea ction s
Derrick L. J . Clive* and J ian Wang
Chemistry Department, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
derrick.clive@ualberta.ca
Received August 29, 2001
The stannane 1, which is simple to prepare, behaves like the conventional reagents Bu3SnH and
Ph3SnH in standard free radical reactions, but with the special characteristic that the tin-containing
byproducts are easily and very largely removed by mild hydrolysis (LiOH-water-THF or TsOH-
water-THF), which converts them into base-soluble (aqueous NaHCO3) materials. The performance
of stannane 1 was evaluated for a range of radical reactions involving halides, selenides, Barton-
McCombie deoxygenation, and enyne cyclization. In several cases the effectiveness of the workup
1
procedure in removing tin species was monitored by H NMR.
In tr od u ction
(5) use of alternatives to stannanes,10 especially si-
lanes,11,12 dialkyl phosphites and hypophosphorous acid,13
and, more recently, R2GaCl2,14 and
It is well-known that there are occasional difficulties
in removing tin species from the products of stannane-
mediated radical reactions. These reactions are important
in organic synthesis; consequently, a number of methods
have had to be developed to facilitate product isolation.
We report the preparation and use of stannane 1sa
substance whose structural features simplify product
isolation.
(6) use of xanthates.15
Resu lts a n d Discu ssion
In connection with some free radical experiments done
in this laboratory, a need developed for a readily acces-
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Prior work on the problem of removing tin-containing
impurities, and the alternative approach of avoiding the
use of tin reagents, includes
(1) development of various workup procedures for
reactions involving stoichiometric R3SnH,1
(2) use of catalytic amounts of a tin hydride or its
precursor and stoichiometric amounts of another hy-
dride (NaBH4,2 NaCNBH3,3 polymethylhydrosiloxane,4
PhSiH35),
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(3) use of modified stannanes,6 including fluorous
stannanes,7
(4) use of solid-supported stannanes either stoichio-
metric8 or catalytic,8c,i,9
To whom correspondence should be addressed. Fax: (780) 492-8231.
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10.1021/jo010885c CCC: $22.00 © 2002 American Chemical Society
Published on Web 01/31/2002

Removal of Sn from Stannane-Mediated Reaction Products
J . Org. Chem., Vol. 67, No. 4, 2002 1193
Sch em e 1
glyoxylic acid hydrate (2) with BiCl3, Zn, and allyl
bromide. Ketalization under standard conditions (2,2-
dimethoxypropane, TsOH·pyridine, acetone) gave the
derived ketal 4. When this was heated with an excess
(1.5 equiv) of Ph3SnH in PhH in the presence of a
catalytic amount of AIBN, the hydrostannylated product
5 could be isolated in 65% yield. Treatment with 1 equiv
17
of I2 served to replace (93%) one of the phenyl groups
by I (5 f 6), and then reduction with NaBH4 gave the
required stannane 1 (98%) as a colorless oil, which was
obtained pure by chromatography over silica gel. We store
the compound under N2 in a refrigerator; the material is
stable for at least two months under these conditions,
but we have not tested older samples.
To establish the properties of the anticipated tin-
containing reaction products, the bromide 7 and the
selenide 8 were also prepared, the former by reaction of
1 with 1-bromopropane under standard conditions (see
the Experimental Section), and the latter by reaction of
1 with selenide 15a (see later). In addition, compounds
6 and 8 (we did not examine 7) were stirred in an aqueous
THF solution of LiOH (ca. 10 equiv) for several hours,
and the presumed products 9a and 9b, obtained by
acidification, were esterified with CH2N2 to give 10a
(16%) and 10b (31%), respectively. Compound 6 was also
hydrolyzed, using acidic conditions (TsOH‚H2O) in MeOH,
to obtain 10a (50%) directly. Both 10a and 10b were
characterized.
sible stannane, RR′R′′SnH, whose derivatives, RR′R′′SnX
(X ) halogen or SePh), could be converted by acid or base
treatment under mild conditions to a carboxylic acid that
is soluble in aqueous NaHCO3. After some exploratory
work to this end, we settled on compound 1, which
satisfies these requirements. This stannane is made by
the straightforward route summarized in Scheme 1.
The known hydroxy acid 316 was easily prepared (95%)
by a literature procedure that calls for treatment of
(12) E.g., see: (a) J ackson, R. A.; Malek, F. J . Chem. Soc., Perkin
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(e) J ang, D. O.; Cho, D. H.; Barton, D. H. R. Synlett 1998, 39-40. (f)
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We have evaluated the performance of reagent 1 by
using it in typical radical reactions, as summarized in
Table 1.
The table shows reduction of bromides (entries 1-4),
a benzylic chloride (entry 5), and selenides (entries 6 and
7), radical cyclization onto a carbon-carbon double bond
(entries 9, 10, 11, and 16), radical cyclization onto a triple
bond (entries 12 and 13), stannane addition to a triple
bond, followed by cyclization of the resulting vinyl radical
and subsequent protodestannylation (entry 14), and
cyclization onto an oxime (entry 15). Entry 8 shows an
example of Barton-McCombie deoxygenation.
The reactions with 1 can be initiated by AIBN in
refluxing PhH or PhMe, or by Et3B and air at room
temperature. In all cases, except those of entries 1
(procedure giving 85% yield), 7, 15, and 16, the crude
reaction mixture was stirred with a solution of LiOH in
aqueous THF for 1.5-3 h (TLC control), and the organic-
soluble product was purified by flash chromatography.
For reduction of 11a (entry 1) we also tried acidic workup,
the crude reaction mixture, in this case, being stirred
with an aqueous THF solution of TsOH. The product 11b
was then isolated in 85% yield. In one case (entry 2), the
1H NMR spectrum of the organic-soluble product after
LiOH treatment was measured before and after flash
chromatography. In two cases (entries 1 and 6) the same
two measurements were again made, but in addition, the
(17) Cf. Wardell, J . L.; Wigzell, J . McM. J . Chem. Soc., Dalton Trans.
1982, 2321-2326.

1194 J . Org. Chem., Vol. 67, No. 4, 2002
Clive and Wang
Ta ble 1a ,b
a
b
Reaction conditions, unless indicated otherwise: 1, AIBN, PhH or toluene, reflux. Workup, unless indicated otherwise: LiOH, water-
THF, extract with Et2O, wash with NaHCO3, flash chromatography. c Workup: TsOH‚H2O, aqueous THF, extract with Et2O, wash with
NaHCO3, flash chromatography. Room temperature. e A single isomer of unestablished geometry. f The initial radical cyclization product
d
was treated with CF3CO2H before LiOH.
1H NMR spectrum was run before workup. The three
spectra for entry 1 (91% yield) are shown in Figure 1.
Exp er im en ta l Section
Gen er a l P r oced u r es. Unless stated to the contrary, all
reactions were done under dry N2, and the general procedures
used previously18 were followed. The symbols s′, d′, t′, and q′
used for 13C NMR signals indicate zero, one, two, and three
attached hydrogens, respectively, the assignments being made
from APT spectra. Known reaction products were identified
by comparison of their NMR spectra (usually both 1H NMR
and 13C NMR) with reported values.
Gen er a l P r oced u r es for Ra d ica l Rea ction s a n d Wor k -
u p . (a ) Th er m a l Ra d ica l Rea ction s. The substrate (0.2
mmol) was placed in a round-bottomed flask carrying a reflux
condenser closed by a septum. The flask was flushed with N2,
and the contents were kept under a slight positive pressure
of N2. PhH or PhMe (3 mL) was injected, and the flask was
lowered into a preheated oil bath set at 85 °C, or at 125 °C in
the case of PhMe. A solution of both stannane 1 (0.28 mmol,
1.4 equiv) and AIBN (1 mg) in the same solvent (3 mL, plus 1
mL as a rinse) was injected in one portion (except for the
radical cyclizations, in which case the addition was made over
6 h). Refluxing was continued for 2-10 h after the addition.
The mixture was cooled and evaporated. Aqueous LiOH (1 M,
2 mL) in THF (2 mL) or aqueous TsOH (0.25 M, 2 mL) in THF
(2 mL) was added to the residue, and the mixture was stirred
at room temperature for 1.5-3 h (TLC control). After all the
tin dioxolanone had been hydrolyzed, Et2O (20 mL) was added,
These spectra establish that the LiOH treatment
removes all but traces of aryl-containing species, but
leaves slight impurities (signals at δ 1.4, 1.5, and 3.6).
All these impurities are removed by flash chromatogra-
phy (in this case, using hexane as eluant). When acidic
workup was used after reduction of 11a (entry 1, 85%
yield), the three 1H NMR spectra (see the Supporting
Information) were very similar to those shown in Figure
1
1. The three H NMR spectra obtained from the experi-
ment in entry 6 (see the Supporting Information) were
comparable to those obtained from the experiment of
entry 1.
While most of the experiments listed in Table 1 give
products that are stable to mild base (LiOH and NaH-
CO3), for the examples of entries 7, 15, and 16 we used
acidic conditions for workup, followed by extraction of the
tin species into saturated aqueous NaHCO3.
Con clu sion
Overall, our experiments show that reagent 1 behaves
similarly to the standard Bu3SnH of Ph3SnH, with the
additional characteristic that the tin-containing byprod-
ucts are easily removed.
(18) Clive, D. L. J .; Wickens, P. L.; Sgarbi, P. W. M. J . Org. Chem.
1996, 61, 7426-7437.

Removal of Sn from Stannane-Mediated Reaction Products
J . Org. Chem., Vol. 67, No. 4, 2002 1195
25.8 (q′), 27.1 (q′), 35.9 (t′), 73.6 (d′), 110.4 (s′), 128.5 (d′), 130.0
(d′), 137.0 (d′), 138.6 (s′), 173.2 (s′); exact mass m/z calcd for
C26H28O3120Sn 508.10605, found 508.10564. Anal. Calcd for
C
26H28O3Sn: C, 61.57; H, 5.56. Found: C, 61.43; H, 5.45.
2,2-Dim eth yl-5-[3-[iod o(d ip h en yl)sta n n yl]p r op yl]-1,3-
d ioxola n -4-on e (6). A solution of I2 (0.64 g, 2.5 mmol) in PhH
(30 mL) was added over 30 min to a stirred solution of 5 (1.28
g, 2.5 mmol) in PhH (20 mL). Stirring was continued for 5-10
h (TLC control), and the solvent was evaporated. Rapid (less
than 30 min) flash chromatography of the residue over silica
gel (2 × 15 cm), using 1:4 EtOAc-hexane, gave 6 (1.31 g, 93%)
as a colorless oil: FTIR (CH2Cl2, cast) 3065, 1790, 1430 cm-1
;
1H NMR (CDCl3, 300 MHz) δ 1.49 (s, 3 H), 1.53 (s, 3 H), 1.72-
2.04 (m, 6 H), 4.34-4.39 (m, 1 H), 7.35-7.70 (m, 10 H); 13C
NMR (CDCl3, 100.6 MHz) δ 16.2 (t′), 22.7 (t′), 25.8 (q′), 27.2
(q′), 35.0 (t′), 73.6 (d′), 110.6 (s′), 129.0 (d′), 130.1 (d′), 136.1
120
(d′), 137.0 (s′), 173.0 (s′); exact mass m/z calcd for C20H23IO3
-
Sn 557.97137, found 557.97294. Anal. Calcd for C20H23IO3Sn:
C, 43.13; H, 4.16; I, 22.78. Found: C, 43.23; H, 4.11; I, 22.41.
2,2-Dim et h yl-5-[3-(d ip h en ylst a n n yl)p r op yl]-1,3-d iox-
ola n -4-on e (1). NaBH4 (44 mg, 1.1 mmol) was added to a
stirred and cooled (0 °C) solution of 6 (636 mg, 1.1 mmol) in
dry MeOH (20 mL). Stirring was continued for 3 h at 0 °C,
and the mixture was then quenched with EtOAc (20 mL),
followed by water (20 mL). The mixture was extracted with
EtOAc (3 × 20 mL), and the combined organic extracts were
dried (MgSO4) and evaporated. Flash chromatography of the
residue over silica gel (2 × 10 cm), using 1:4 EtOAc-hexane,
gave stannane 1 (484.2 mg, 98%) as a colorless oil which we
store under N2 in a refrigerator: FTIR (CD2Cl2, cast) 3068,
1792, 1429 cm-1; 1H NMR (CDCl3, 500 MHz) δ 1.35-1.41 (m,
2 H), 1.49 (s, 3 H), 1.52 (s, 3 H), 1.75-1.97 (m, 4 H), 4.34-
4.38 (m, 1 H), 6.16 (t, J ) 1.8 Hz, 1 H), 7.31-7.37 (m, 6 H),
7.45-7.56 (m, 4 H); 13C NMR (CD2Cl2, 75.5 MHz) δ 10.2 (t′),
23.2 (t′), 25.9 (q′), 27.4 (q′), 36.1 (t′), 74.0 (d′), 110.8 (s′), 129.1
(d′), 129.2 (d′), 137.6 (d′), 138.3 (s′), 173.5 (s′); exact mass m/z
calcd for C20H24NaO3120Sn 455.06451, found 455.06535. Anal.
Calcd for C20H24O3Sn: C, 55.74; H, 5.56. Found: C, 55.99; H,
5.42.
F igu r e 1. Trace A: spectrum measured after evaporation of
reaction solvent for entry 1 of Table 1. Trace B: spectrum
measured after LiOH treatment. Inset: expansion (ca. 4×) of
region δ 6.5-7.4. The chloroform signal is truncated. Trace
C: spectrum measured after flash chromatography.
and the organic layer was washed with saturated NaHCO3 (3
× 20 mL), dried (MgSO4), and evaporated. Flash chromatog-
raphy of the residue over silica gel then gave the product.
(b) Room Tem p er a tu r e Ra d ica l Rea ction s. Stannane
1 (1.4 mmol) in PhH (4 mL) and Et3B (1 M in hexane, 1.1 mL)
were added to a stirred solution of the substrate (1.0 mmol)
in hexane (5 mL) contained in a flask fitted with a calcium
sulfate guard tube. The mixture was stirred for 11 h with
exposure to air (via the guard tube), and the same workup
procedure was followed as for the thermal method.
2,2-Dim et h yl-5-[3-[b r om o(d ip h en yl)st a n n yl]p r op yl]-
1,3-d ioxola n -4-on e (7). 1-Bromopropane (0.5 mL) was added
to a solution of 1 (217 mg, 0.5 mmol) and AIBN (3 mg, 0.02
mmol) in PhMe (8 mL). The mixture was then heated at 110
°C for 3 h, cooled to room temperature, and evaporated. Flash
chromatography of the residue over silica gel (1 × 15 cm), using
1:4 EtOAc-hexane, gave bromide 7 (152.5 mg, 60%) as a
2,2-Dim eth yl-5-(2-pr open yl)-1,3-dioxolan -4-on e (4). 2-Hy-
droxy-4-pentenoic acid16 (6.00 g, 51.7 mmol) was dissolved in
2,2-dimethoxypropane (150 mL). Pyridinium p-toluenesulfonate
(0.50 g, 1.99 mmol) was added, and the mixture was stirred
for 5 h (TLC control, silica, 1:4 EtOAc-hexane). Evaporation
of the solvent and flash chromatography of the residue over
silica gel (2.5 × 20 cm), using 1:19 EtOAc-hexane, gave
acetonide 4 (6.14 g, 76%) as a colorless oil: FTIR (CDCl3, cast)
colorless oil: FTIR (CHCl3, cast) 3066, 1789, 1430 cm-1 1H
;
NMR (CDCl3, 400 MHz) δ 1.49 (s, 3 H), 1.54 (s, 3 H), 1.66-
2.04 (m, 6 H), 4.34-4.39 (m, 1 H), 7.38-7.68 (m, 10 H); 13C
NMR (CDCl3, 100.6 MHz) δ 16.7 (t′), 21.8 (t′), 25.7 (q′), 27.1
(q′), 35.0 (t′), 73.5 (d′), 110.6 (s′), 129.0 (d′), 130.2 (d′),
135.8 (d′), 137.9 (s′), 173.0 (s′); exact mass m/z calcd for
1
2918, 1797 cm-1; H NMR (CDCl3, 400 MHz) δ 1.53 (s, 3 H),
C
20H2381BrO3120Sn 511.98322, found 511.98251. Anal. Calcd for
1.60 (s, 3 H), 2.45-2.54 (m, 1 H), 2.62-2.70 (m, 1 H), 4.45 (q,
J ) 4.6, 6.6 Hz, 1 H), 5.16-5.26 (m, 2 H), 5.77-5.88 (m, 1 H);
13C NMR (CDCl3, 100.6 MHz) δ 25.9 (q′), 27.2 (q′), 35.8 (t′),
73.8 (d′), 110.7 (s′), 119.2 (d′), 131.9 (t′), 172.6 (s′); exact mass
m/z calcd for C8H12O3 156.07864, found 156.07834. Anal. Calcd
for C8H12O3: C, 61.47; H, 7.74. Found: C, 60.82; H, 7.94.
2,2-Dim eth yl-5-[3-(tr ip h en ylsta n n yl)p r op yl]-1,3-d iox-
ola n -4-on e (5). A solution of 4 (1.56 g, 10.0 mmol) in dry PhH
(10 mL) was added to freshly prepared Ph3SnH (5.26 g, 15.0
mmol, made from Ph3SnCl and LiAlH419). AIBN (10 mg) was
added to the mixture, which was then heated at 90 °C for 10-
24 h (TLC control; N2 atmosphere). Evaporation of the solvent
and rapid (no more than 30 min) flash chromatography of the
residue over silica gel (3 × 25 cm), using 1:49 EtOAc-hexane,
gave stannane 5 (3.29 g, 65%) as a colorless oil: FTIR (CDCl3,
C20H23BrO3Sn: C, 47.10; H, 4.55. Found: C, 47.45; H, 4.59.
2,2-Dim et h yl-5-[3-[p h en ylselen o(d ip h en yl)st a n n yl]-
p r op yl]-1,3-d ioxola n -4-on e (8). Stannane 1 (227 mg, 0.5
mmol) and AIBN (5 mg, 0.03 mmol) in PhMe (5 mL, plus 3
mL as a rinse) were added in one portion to a refluxing solution
of (3aR,6R,6aR)-hexahydro-6-(phenylseleno)-2H-cyclopenta[b]-
furan-2-one (15a )20 (106 mg, 0.4 mmol) in PhMe (3 mL).
Refluxing was continued overnight, and the solvent was then
evaporated. Flash chromatography of the residue over silica
gel (1 × 15 cm), using 1:9 EtOAc-hexane, gave 8 (152 mg,
69%) as a colorless oil: FTIR (CH2Cl2, cast) 3064, 2925, 1791,
1576, 1474 cm-1; 1H NMR (CDCl3, 500 MHz) δ 1.40-1.45 (m,
2 H), 1.48 (s, 3 H), 1.50 (s, 3 H), 1.65-1.88 (m, 4 H), 4.28 (q,
J ) 4.0, 7.0 Hz, 1 H), 7.02 (t, J ) 7.5 Hz, 2 H), 7.12 (t, J ) 7.4
Hz, 1 H), 7.30-7.50 (m, 12 H); 13C NMR (CDCl3, 125.7 MHz)
δ 13.9 (t′), 22.2 (t′), 25.9 (q′), 27.2 (q′), 35.5 (t′), 73.5 (d′), 110.4
(s′), 124.6 (s′), 126.6 (d′), 128.6 (d′), 128.7 (d′), 129.4 (d′), 136.4
(d′), 136.5 d′), 138.2 (s′), 172.9 (s′); exact mass m/z calcd for
cast) 3063, 1792, 1429 cm-1 1H NMR (CDCl3, 500 MHz) δ
;
1.477 (s, 3 H), 1.481 (s, 3 H), 1.50-1.53 (m, 2 H), 1.75-1.97
(m, 4 H), 4.33-4.36 (m, 1 H), 7.33-7.39 (m, 9 H), 7.46-7.59
(m, 6 H); 13C NMR (CDCl3, 100.6 MHz) δ 10.4 (t′), 22.3 (t′),
C
26H28NaO380Se120Sn 611.01233, found 611.01175.
(19) Van der Kerk, G. J . M.; Noltes, J . G.; Luijten, J . G. A. J . Appl.
Chem. 1957, 7, 366-369.
(20) Clive, D. L. J .; Russell, C. G.; Chittattu, G.; Singh, A. Tetra-
hedron 1980, 36, 1399-1408.

1196 J . Org. Chem., Vol. 67, No. 4, 2002
Clive and Wang
Meth yl 5-[Iodo(diph en yl)stan n yl]-2-h ydr oxypen tan oate
(10a ). (a) Aqueous LiOH (1 M, 2 mL) was added to a stirred
solution of compound 6 (133 mg, 0.24 mmol) in THF (2 mL).
Stirring was continued for 1 h, and the mixture was acidified
with concentrated hydrochloric acid. The precipitate was
collected, washed with CH2Cl2, and dried under an oil pump
vacuum. The solid (62 mg) was then suspended in a mixture
of MeOH (2 mL) and PhMe (5 mL), and Me3SiCHN2 (2 M in
hexane, 0.3 mL, 0.6 mmol) was added dropwise with stirring.
Stirring was continued for 15 min. AcOH (0.5 mL) was added
to destroy the excess Me3SiCHN2, and the mixture was
extracted with EtOAc. The combined organic extracts were
dried (MgSO4) and evaporated. Flash chromatography of the
residue over silica gel (1 × 10 cm), using EtOAc, gave 10a (20
mg, 16%). See the following experiment for characterization
data.
using 11a (70 mg, 0.28 mmol) in PhMe (3 mL), stannane 1
(170 mg, 0.39 mmol) and AIBN (2 mg, 0.01 mmol) in PhMe (5
mL, plus 2 mL as a rinse), an addition time of 5 min, and an
arbitrary reflux time of 5 h after the addition. The general
acidic workup procedure was followed, using aqueous TsOH
(0.25 M, 1 mL) in THF (2 mL) and a reaction time of 3 h. Flash
chromatography of the crude product over silica gel (1 × 10
cm), using hexane, gave 11b (41.1 mg, 85%).
In this experiment the 1H NMR spectra of the crude product,
of the material obtained after TsOH treatment (and washing
with aqueous NaHCO3), and of the final product were mea-
sured (see the Supporting Information).
(c) Room Tem p er a tu r e Ra d ica l Rea ction a n d Ba sic
Wor k u p . The general room temperature procedure for radical
reactions was followed, using 11a (66 mg, 0.27 mmol) in PhH
(2 mL), stannane 1 (160 mg, 0.37 mmol) in PhH (3 mL, plus 1
mL as a rinse), Et3B (1 M in hexane, 0.35 mL, 0.35 mmol),
and an arbitrary reaction time of 10 h after the addition. The
general basic workup procedure was followed, using aqueous
LiOH (1 M, 3 mL) in THF (3 mL) and a reaction time of 3 h.
Flash chromatography of the crude product over silica gel (1
× 10 cm), using hexane, gave 11b (42.0 mg, 93%).
(b) Compound 6 (40 mg, 0.07 mmol) was stirred for 1.5 h in
MeOH (3 mL) containing TsOH‚H2O (3 mg). Evaporation of
the solvent and flash chromatography of the residue over silica
gel (1 × 15 cm), using EtOAc, gave 10a (19.6 mg, 50%) as a
colorless oil: FTIR (CDCl3, cast) 3425 (br), 3064, 1733, 1429
1
cm-1; H NMR (CDCl3, 300 MHz) δ 1.65-2.00 (m, 6 H), 2.72
(br s, 1 H), 3.72 (s, 3 H), 4.15 (d, J ) 7.1 Hz, 1 H), 7.33-7.43
(m, 6 H), 7.54-7.62 (m, 4 H); 13C NMR (CDCl3, 75.5 MHz) δ
17.2 (t′), 22.5 (t′), 37.4 (t′), 52.6 (q′), 70.0 (d′), 128.9 (d′), 130.0
(d′), 136.1 (d′), 137.5 (s′), 175.3 (s′); exact mass m/z calcd for
Na p h th a len e (12b). (a ) Th er m a l Rea ction . The general
thermal procedure for radical reactions was followed, using
1-bromonaphthalene (12a ) (47.0 mg, 0.23 mmol) in PhH (4
mL), stannane 1 (132 mg, 0.31 mmol) and AIBN (1 mg, 0.006
mmol) in PhH (4 mL, plus 2 mL as a rinse), an addition time
of 5 min, and an arbitrary reflux time of 3 h after the addition.
The general basic workup procedure was followed, using
aqueous LiOH (1 M, 2 mL) in THF (2 mL) and a reaction time
of 3 h. Flash chromatography of the crude product over silica
gel (1 × 10 cm), using hexane, gave 12b (25.1 mg, 86%).
C
18H21INaO3120Sn 554.94497, found 554.94539.
Met h yl
5-[(Dip h en yl)(p h en ylselen o)st a n n yl]-2-h y-
d r oxyp en ta n oa te (10b). Conversion of 8 to 10b was done in
two slightly different ways: (a) After the LiOH hydrolysis of
the crude reaction mixture from reduction of 14a (59 mg) (see
later), the aqueous LiOH layer was acidified with concentrated
hydrochloric acid, and the precipitate was collected, washed
with CH2Cl2, and dried under an oil pump vacuum. The solid
(63 mg) was then suspended in a mixture of MeOH (2 mL)
and PhMe (5 mL), and Me3SiCHN2 (2 M in hexane, 0.25 mL,
0.5 mmol) was added dropwise with stirring. Stirring was
continued for 15 min. AcOH (0.5 mL) was added to destroy
the excess Me3SiCHN2, and the mixture was extracted with
EtOAc. The combined organic extracts were dried (MgSO4) and
evaporated. Flash chromatography of the residue over silica
gel (1 × 10 cm), using 1:9 EtOAc-hexane, gave 10b (20 mg,
31%) as a yellow oil: FTIR (CHCl3, cast) 3485, 3063, 1958,
(b) Room Tem p er a tu r e Rea ction . The general room
temperature procedure for radical reactions was followed,
using 12a (42 mg, 0.20 mmol) in PhH (4 mL), stannane 1 (121
mg, 0.28 mmol) in PhH (3 mL, plus 1 mL as a rinse), Et3B (1
M in hexane, 0.3 mL, 0.3 mmol), and an arbitrary reaction
time of 10 h after the addition. The general basic workup
procedure was followed, using aqueous LiOH (1 M, 2 mL) in
THF (2 mL) and a reaction time of 3 h. Flash chromatography
of the crude product over silica gel (1 × 10 cm), using hexane,
gave naphthalene 12b (20.8 mg, 81%).
1
1735, 1576, 1429 cm-1; H NMR (CDCl3, 400 MHz) δ 1.37-
1-Meth yln a p h th a len e (13b). The general thermal proce-
dure for radical reactions was followed, using 1-chlorometh-
ylnaphthalene (13a ) (43.0 mg, 0.24 mmol) in PhH (4 mL),
stannane 1 (147 mg, 0.34 mmol) and AIBN (2 mg, 0.01 mmol)
in PhH (5 mL, plus 3 mL as a rinse), an addition time of 5
min, and an arbitrary reflux time of 10 h after the addition.
The general basic workup procedure was followed, using
aqueous LiOH (1 M, 2 mL) in THF (2 mL) and a reaction time
of 1.5 h. Flash chromatography of the crude product over silica
gel (1 × 10 cm), using 1:49 EtOAc-hexane, gave 1-methyl-
naphthalene 13b (32.0 mg, 92%).
1.85 (m, 6 H), 2.57 (d, J ) 5.7 Hz, 1 H), 3.71 (s, 3 H), 4.07-
4.13 (m, 1 H), 7.02 (t, J ) 7.4 Hz, 2 H), 7.12 (tt, J ) 1.2, 7.4
Hz, 1 H), 7.30-7.54 (m, 12 H); 13C NMR (CDCl3, 125.7 MHz)
δ 14.1 (t′), 22.0 (t′), 38.2 (t′), 52.5 (q′), 69.9 (d′), 124.7 (s′), 126.5
(d′), 128.6 (d′), 128.6 (d′), 129.3 (d′), 136.4 (d′), 136.5 (d′), 138.4
(s′), 175.4 (s′); exact mass m/z calcd for C18H21O3120Sn (M -
PhSe) 405.05127, found 405.05229. Anal. Calcd for C24H26O3-
SeSn: C, 51.42; H, 4.68. Found: C, 51.34; H, 4.69.
(b) Anhydrous K2CO3 (3 mg, 0.02 mmol) was added to a
stirred solution of 8 (94 mg, 0.16 mmol) in MeOH (5 mL), and
stirring was continued for 3 h. Evaporation of the solvent and
flash chromatography of the residue over silica gel (1 × 15
cm), using 1:19 EtOAc-hexane, gave 10b (65 mg, 72%) as a
yellow oil.
Dod eca n e (11b) fr om 11a . (a ) Th er m a l Ra d ica l Rea c-
tion a n d Ba sic Wor k u p . The general thermal procedure for
radical reactions was followed, using 1-bromododecane (11a )
(64 mg, 0.26 mmol) in PhMe (1 mL), stannane 1 (155 mg, 0.36
mmol) and AIBN (2 mg, 0.01 mmol) in PhMe (5 mL, plus 1
mL as a rinse), an addition time of 1 h, and an arbitrary reflux
time of 3 h after the addition. The general basic workup
procedure was followed, using aqueous LiOH (1 M, 2 mL) in
THF (2 mL) and a reaction time of 3 h. Flash chromatography
of the crude product over silica gel (1 × 10 cm), using hexane,
gave 11b (40.1 mg, 91%).
11b fr om 14a . The general thermal procedure for radical
reactions was followed, using (1-phenylseleno)dodecane (14a )
(59 mg, 0.18 mmol) in PhMe (1.5 mL), stannane 1 (103 mg,
0.24 mmol) and AIBN (2 mg, 0.01 mmol) in PhMe (4 mL, plus
1 mL as a rinse), an addition time of 5 min, and an arbitrary
reflux time of 5 h after the addition. The general basic workup
procedure was followed, using aqueous LiOH (1 M, 2 mL) in
THF (3 mL) and a reaction time of 2 h. Flash chromatography
of the crude product over silica gel (1 × 10 cm), using hexane,
gave 11b (25.2 mg, 82%).
cis-Hexa h yd r o-2H-cyclop en ta [b]fu r a n -2-on e (15b). The
general thermal procedure for radical reactions was followed,
using 15a 20 (89 mg, 0.32 mmol) in PhMe (4 mL), stannane 1
(157 mg, 0.36 mmol) and AIBN (3 mg, 0.02 mmol) in PhMe (4
mL, plus 2 mL as a rinse), an addition time of 5 min, and an
arbitrary reflux time of 10 h after the addition. The general
acidic workup procedure was followed, using aqueous TsOH
(0.25 M, 1 mL) in THF (3 mL) and a reaction time of 3 h. Flash
chromatography of the crude product over silica gel (1 × 15
In this experiment the 1H NMR spectra of the crude product,
of the material obtained after LiOH treatment, and of the final
product were measured (see Figure 1 and the Supporting
Information).
(b) Th er m a l Ra d ica l Rea ction a n d Acid ic Wor k u p . The
general thermal procedure for radical reactions was followed,

Removal of Sn from Stannane-Mediated Reaction Products
J . Org. Chem., Vol. 67, No. 4, 2002 1197
cm), using 1:19 EtOAc-hexane, gave 15b21 (28.6 mg, 71%) as
a colorless oil.
mg, 0.87 mmol) and PhSeSePh (136 mg, 0.44 mmol) in MeOH
(7 mL) (N2 atmosphere), MeOH (3 mL) being used as a rinse
to transfer all the NaBH4. The mixture was stirred overnight,
and then evaporated. Flash chromatography of the residue
over silica gel (1 × 20 cm), using hexane, gave 19a (230 mg,
83%) as colorless oil: FTIR (CDCl3, cast) 3072, 3027, 2926,
5r-Ch olesta n e (16b). The general thermal procedure for
radical reactions was followed, using 16a (37.0 mg, 0.074
mmol) in PhMe (1.5 mL), stannane 1 (48 mg, 0.11 mmol) and
AIBN (2 mg, 0.01 mmol) in PhMe (1.5 mL, plus 1.5 mL as a
rinse), an addition time of 5 min, and an arbitrary reflux time
of 10 h after the addition. The general basic workup procedure
was followed, using aqueous LiOH (1 M, 1 mL) in THF (1 mL)
and a reaction time of 1.25 h. Flash chromatography of the
crude product over silica gel (1 × 10 cm), using hexane, gave
16b (25.2 mg, 91%).
1-Met h yl-1,2-d ih yd r on a p h t h o[2,1-b]fu r a n (17b) a n d
2,3-Dih yd r o-1H-n a p h th o[2,1-b]p yr a n (17c). The general
thermal procedure for radical cyclization was followed, using
17a 22 (57 mg, 0.2 mmol) in PhH (3 mL), stannane 1 (131 mg,
0.3 mmol) and AIBN (1 mg, 0.006 mmol) in PhH (3 mL, plus
2 mL as a rinse), an addition time of 5 h, and an arbitrary
reflux time of 6 h after the addition. The general basic workup
procedure was followed, using aqueous LiOH (1 M, 2 mL) in
THF (2 mL) and a reaction time of 1.5 h. Flash chromatogra-
phy of the crude product over silica gel (1 × 10 cm), using 1:19
EtOAc-hexane, gave 17b23 (23.7 mg, 63%) and 17c23 (14 mg,
31%).
1
1640, 1579, 1477 cm-1; H NMR (CDCl3, 500 MHz) δ 1.68-
1.76 (m, 1 H), 1.82-2.00 (m, 3 H), 2.82-2.88 (m, 1 H), 3.12-
3.19 (m, 2 H), 4.87-4.94 (m, 2 H), 5.67-5.76 (m, 1 H), 7.10-
7.44 (m, 10 H); 13C NMR (CDCl3, 100.6 MHz) δ 31.5 (t′), 35.2
(t′), 35.3 (t′), 45.6 (d′), 114.7 (t′), 126.62 (d′), 126.64 (d′), 127.5
(d′), 128.4 (d′), 128.9 (d′), 130.8 (s′), 132.5 (d′), 138.1 (d′), 143.9
(s′); exact mass m/z calcd for C18H2080Se 316.07303, found
316.07266. Anal. Calcd for
Found: C, 68.35; H, 6.47.
C18H20Se: C, 68.57; H, 6.39.
18b fr om 19a . The general thermal procedure for radical
cyclization was followed, using 19a (77.8 mg, 0.25 mmol) in
PhH (3 mL), stannane 1 (150 mg, 0.35 mmol) and AIBN (4
mg, 0.02 mmol) in PhH (8 mL, plus 2 mL as a rinse), an
addition time of 5 h, and an arbitrary reflux time of 5 h after
the addition. The general basic workup procedure was fol-
lowed, using aqueous LiOH (1 M, 2 mL) in THF (2 mL) and a
reaction time of 2 h. Flash chromatography of the crude
product over silica gel (1 × 10 cm), using hexane, gave 18b
(29.5 mg, 74%).
3-Cyclop en t ylm et h ylen e-2,3-d ih yd r o-5,6-d im et h oxy-
1H-in d en -1-ol (20b). The general thermal procedure for
radical cyclization was followed, using 20a 27 (see below for
characterization data) (83.5 mg, 0.23 mmol) in PhH (10 mL),
stannane 1 (143 mg, 0.33 mmol) and AIBN (2 mg, 0.01 mmol)
in PhH (8 mL, plus 2 mL as a rinse), an addition time of 5 h,
and an arbitrary reflux time of 5 h after the addition. The
general basic workup procedure was followed, using aqueous
LiOH (1 M, 2 mL) in THF (2 mL) and a reaction time of 3 h.
Flash chromatography of the crude product over silica gel (1
× 15 cm), using 3:7 EtOAc-hexane, gave 20b (58.8 mg, 90%)
as a single isomer of unestablished stereochemistry: FTIR
(CH2Cl2, cast) 3383 (br), 2949, 1605, 1500 cm-1; 1H NMR (C6D6,
300 MHz) δ 1.25-2.00 (m, 9 H), 2.46-2.56 (m, 1 H), 2.58-
2.73 (m, 1 H), 2.96-3.08 (m, 1 H), 3.41 (2 s, each 3 H), 5.05
(dd, J ) 3.2, 7.3 Hz, 1 H), 5.82 (dt, J ) 2.3, 9.1 Hz, 1 H), 6.80
(s, 1 H), 6.91 (s, 1 H); 13C NMR (C6D6, 75.5 MHz) (two signals
overlap in this spectrum) δ 25.5 (t′), 33.7 (t′), 40.2 (t′), 40.8
(d′), 55.3 (q′), 73.4 (d′), 102.8 (d′), 107.9 (d′), 123.1 (d′), 133.7
(s′), 137.9 (s′), 139.5 (s′), 150.9 (s′), 151.1 (s′); exact mass m/z
calcd for C17H22O3 274.15689, found 274.15712.
[1-(Iod om eth yl)-4-p en ten yl]ben zen e (18a ). Ph3P (1.44
g, 5.5 mmol) and imidazole (375 mg, 5.5 mmol) were added to
a stirred solution of 2-phenyl-5-hexen-1-ol24 (485 mg, 2.8 mmol)
in CH2Cl2 (20 mL).25 Stirring was continued for 10 min, and
I2 (1.40 g, 5.5 mmol) was tipped into the mixture. Stirring was
continued for 3 h, and the mixture was then washed with
saturated aqueous Na2S2O3 (20 mL) and extracted with CH2-
Cl2. The combined organic extracts were dried (MgSO4) and
evaporated. Flash chromatography of the residue over silica
gel (2 × 15 cm), using 1:99 EtOAc-hexane, gave 18a (751 mg,
95%) as a colorless oil: FTIR (CDCl3, cast) 3062, 2929, 1640,
1
1494 cm-1; H NMR (CDCl3, 500 MHz) δ 1.67-1.76 (m, 1 H),
1.85-2.03 (m, 3 H), 2.82-2.89 (m, 1 H), 3.32-3.41 (m, 2 H),
4.92-4.97 (m, 2 H), 5.69-5.78 (m, 1 H), 7.13-7.16 (m, 2 H),
7.22-7.34 (m, 3 H); 13C NMR (CDCl3, 125.7 MHz) δ 13.7 (t′),
31.6 (t′), 34.9 (t′), 47.6 (d′), 115.0 (t′), 127.0 (d′), 127.4 (d′), 128.5
(d′), 137.8 (d′), 142.7 (s′); exact mass m/z calcd for C12H15
I
286.02185, found 286.02149. Anal. Calcd for C12H15I: C, 50.37;
H, 5.28. Found: C, 50.39; H, 5.30.
cis- a n d tr a n s-3-Meth yl-1-p h en ylcyclop en ta n e (18b)
fr om 18a . The general thermal procedure for radical cycliza-
tion was followed, using 18a (81.5 mg, 0.29 mmol) in PhH (2
mL), stannane 1 (180 mg, 0.42 mmol) and AIBN (4 mg, 0.02
mmol) in PhH (5 mL, plus 3 mL as a rinse), an addition time
of 5 h, and an arbitrary reflux time of 3 h after the addition.
The general basic workup procedure was followed, using
aqueous LiOH (1 M, 3 mL) in THF (3 mL) and a reaction time
of 2 h. Flash chromatography of the crude product over silica
gel (1 × 10 cm), using hexane, gave 18b26 (38.1 mg, 83%): 1H
NMR (CDCl3, 500 MHz) δ 1.05 (q, J ) 6.5 Hz, 3 H), 1.17-2.28
(m, 7 H), 3.00-3.19 (m, J ) 8.4 Hz, 1 H), 7.12-7.29 (m, 5 H);
13C NMR (CDCl3, 100.6 MHz) δ 21.0 (q′), 33.8 (d′), 34.1 (t′),
35.4 (t′), 42.5 (d′), 44.5 (d′), 125.5 (d′), 127.0 (d′), 128.1 (d′),
147.0 (s′).
Data for 20a : FTIR (CH2Cl2, cast) 3513, 2956, 2868, 1959,
1
1603, 1503.5, 1463, 1439 cm-1; H NMR (CDCl3, 300 MHz) δ
1.45-1.61 (m, 4 H), 1.64-1.78 (m, 2 H), 1.83-1.95 (m, 2 H),
2.40-2.50 (m, 1 H), 2.52-2.68 (m, 2 H), 2.68-2.79 (m, 1 H),
3.85 (2 s, each 3 H), 5.05 (q, J ) 5 Hz, 1 H), 6.95 (s, 1 H), 7.10
(s, 1 H); 13C NMR (CDCl3, 75.5 MHz) δ 25.0 (t′), 28.6 (t′), 30.3
(d′), 34.0 (t′), 56.0 (q′), 56.2 (q′), 71.0 (d′), 75.0 (s′), 88.3 (s′),
109.8 (d′), 115.6 (s′), 115.2 (d′), 133.8 (s′), 148.6 (s′), 148.9 (s′);
exact mass m/z calcd for C17H2179BrNaO3 375.05718, found
375.05716.
cis-2,2-Bis(1,1-d im eth yleth yl)h exa h yd r o-6,6-d im eth yl-
fu r o[3,4-d ]-1,2-oxa silole (21b). The general thermal proce-
dure for radical cyclization was followed, using 21a 28 (42.5 mg,
0.10 mmol) in PhH (3 mL), stannane 1 (65 mg, 0.15 mmol)
and AIBN (2 mg, 0.01 mmol) in PhH (6 mL, plus 1 mL as a
rinse), an addition time of 7 h, and an arbitrary reflux time of
5 h after the addition. The general basic workup procedure
was followed, using aqueous LiOH (1 M, 1 mL) in THF (2 mL)
and a reaction time of 1 h. Flash chromatography of the crude
product over silica gel (1 × 10 cm), using 1:19 EtOAc-hexane,
gave 21b (20.9 mg, 78%) as a colorless oil: FTIR (CH2Cl2, cast)
In this experiment the 1H NMR spectra of the crude product,
of the material obtained after LiOH treatment, and of the final
product were measured (see the Supporting Information).
[(2-P h en ylh ex-5-en yl)selen o]ben zen e (19a ). NaBH4 (52
mg, 1.35 mmol) was added to a stirred solution of 18a (250
(21) Newton, R. F.; Reynolds, D. P.; Crossland, N. M.; Kelly, D. R.;
Roberts, S. M. J . Chem. Soc., Perkin Trans. 1 1980, 1583-1586.
(22) Made from 2-naphthalenol by bromination (NBS, 98%) (Car-
ren˜o, M. C.; Ruano, G. J . L.; Sanz, G.; Toledo, M. A.; Urbano, A. Synlett
1997, 1241-1242) and O-allylation (81%) (Olivero, S.; Dun˜ach, E. Eur.
J . Org. Chem. 1999, 8, 1885-1891).
2931, 2857, 1472, 1057 cm-1 1H NMR (CDCl3, 400 MHz) δ
;
0.62 (q, J ) 2.8, 15.5 Hz, 1 H), 1.00 (s, 9 H), 1.06 (s, 9 H),
1.06-1.10 (m, 1 H), 1.14 (s, 3 H), 1.28 (s, 3 H), 2.90-3.00 (m,
1 H), 3.46 (q, J ) 6.6, 9.0 Hz, 1 H), 4.00 (t, J ) 8.9 Hz, 1 H),
(23) Abeywickrema, A. N.; Beckwith, A. L. J .; Gerba, S. J . Org.
Chem. 1987, 52, 4072-4078.
(24) J ung, M. E.; Vu, B. T. J . Org. Chem. 1996, 61, 4427-4433.
(25) Cf. Berkenbusch, T.; Bru¨ckner, R. Tetrahedron 1998, 54,
11461-11470.
(27) Compound 20a was a gift from Haikang Yang of this laboratory.
(28) Clive, D. L. J .; Yang, W.; MacDonald, A.; Wang, Z.; Cantin, M.
J . Org. Chem. 2001, 66, 1966-1983.
(26) Anderson, C. D.; Sharp, J . T.; Strathdee, R. S. J . Chem. Soc.,
Perkin Trans. 1 1979, 2730-2735.

1198 J . Org. Chem., Vol. 67, No. 4, 2002
Clive and Wang
4.08 (d, J ) 6.6 Hz, 1 H); 13C NMR (CDCl3, 100.6 MHz) δ 10.1
(s′), 19.7 (s′), 21.2 (t′), 22.4 (q′), 25.6 (q′), 27.5 (q′), 27.9 (t′),
41.9 (d′), 73.1 (t′), 84.2 (s′), 89.1 (d′); exact mass m/z calcd for
chromatography of the crude product over silica gel (1 × 10
cm), using pentane, gave 22b31 (28.6 mg, 70%) as a colorless
oil.
C
15H30O2Si 270.20151, found 270.20174.
4-(2-Cyclop en ten -1-yl)-1-bu tyn e (22a ). (a ) [4-(2-Cyclo-
Dih yd r o-2,3-fu r a n d ion e 3-Oxim e (23b). The general
thermal procedure for radical cyclization was followed, using
23a 32 (51 mg, 0.12 mmol) in PhH (3 mL), stannane 1 (73 mg,
0.17 mmol) and AIBN (2 mg, 0.01 mmol) in PhH (6 mL, plus
2 mL as a rinse), an addition time of 5 h, and an arbitrary
reflux time of 10 h after the addition. The general acidic
workup procedure was followed, using aqueous TsOH (0.25
M, 1 mL) in THF (2 mL) and a reaction time of 3 h. Flash
chromatography of the crude product over silica gel (1 × 10
cm), using 1:1 EtOAc-hexane, gave 23b32 (12.2 mg, 88%) as
a white solid. After a CD3OD solution of 23b had been stored
overnight while the 13C NMR spectrum was being measured,
a new set of signals appeared, which we arbitrarily attribute
to a geometrical isomer. The isomers could not be separated,
but by comparison with spectra run on fresh samples, the
signals corresponding to each isomer could be identified. Data
for the original isomer: 1H NMR (CD3OD, 400 MHz) δ 3.01
(t, J ) 7.3 Hz, 2 H), 4.48 (t, J ) 7.3 Hz, 2 H); 13C NMR (CD3-
OD, 100.6 MHz) δ 24.9 (t′), 67.0 (t′), 147.8 (s′), 168.7 (s′). Data
for the new isomer: 1H NMR (CD3OD, 400 MHz) δ 2.80 (t, J
) 7.3 Hz, 2 H), 3.65 (t, J ) 7.3 Hz, 2 H); 13C NMR (CD3OD,
100.6 MHz) δ 29.4 (t′), 59.2 (t′), 150.8 (s′), 166.2 (s′).
2-Oxa bicyclo[3.3.1]n on a n -3-on e (24b). The general ther-
mal procedure for radical cyclization was followed, using 24a 33
(90 mg, 0.31 mmol) in PhH (10 mL), stannane 1 (185 mg, 0.43
mmol) and AIBN (7 mg, 0.04 mmol) in PhH (8 mL, plus 2 mL
as a rinse), an addition time of 5 h, and an arbitrary reflux
time of 3 h after the addition. The general acidic workup
procedure was followed, using aqueous TsOH (0.25 M, 3 mL)
in THF (3 mL) and a reaction time of 1.5 h. Flash chroma-
tography of the crude product over silica gel (1 × 10 cm), using
3:7 EtOAc-hexane, gave 24b33,34 (392 mg, 91%) as a white
solid.
p en ten -1-yl)bu t-1-yn yl]tr im eth ylsila n e. n-BuLi (2.5 M in
hexane, 7.10 mL, 17.7 mmol) was added dropwise over ca. 10
min to a stirred and cooled (-78 °C) solution of ethynyltri-
methylsilane (2.45 mL, 17.0 mmol) in THF (100 mL). Stirring
at -78 °C was continued for 1.5 h, and neat 3-(2-iodoethyl)-
cyclopentene29 (see below for characterization data) (4.00 g,
18.1 mmol) was added dropwise over ca. 30 min (syringe
pump). The cold bath was removed, and stirring was continued
overnight. The mixture was quenched with water (100 mL)
and extracted with Et2O. The combined organic extracts were
dried (MgSO4) and evaporated. Flash chromatography of the
residue over silica gel (2.5 × 20 cm), using hexane, gave
starting material (2.67 g) and [4-(2-cyclopenten-1-yl)but-1-ynyl]-
trimethylsilane (1.02 g, 88% corrected for recovered starting
material): FTIR (CH2Cl2, cast) 3051, 2956, 2175, 1614, 1450,
1249 cm-1; H NMR (CDCl3, 500 MHz) δ 0.12 (s, 9 H), 1.35-
1
1.42 (m, 1 H), 1.45-1.53 (m, 1 H), 1.58-1.66 (m, 1 H), 1.99-
2.07 (m, 1 H), 2.20-2.36 (m, 4 H), 2.69-2.77 (m, 1 H), 5.63-
5.73 (m, 2 H); 13C NMR (CDCl3, 125.7 MHz) δ 0.3 (q′), 18.4
(t′), 29.5 (t′), 32.0 (t′), 34.9 (t′), 44.9 (d′), 84.3 (s′), 107.6 (s′),
130.7 (d′), 134.3 (d′); exact mass m/z calcd for
192.13342, found 192.13369.
C12H20Si
Data for 3-(2-iodoethyl)cyclopentene: 1H NMR (CDCl3, 500
MHz) δ 1.33-1.41 (m, 1 H), 1.76-1.85 (m, 1 H), 1.90-1.98
(m, 1 H), 2.01-2.09 (m, 1 H), 2.24-2.36 (m, 2 H), 2.70-2.78
(m, 1 H), 3.13-3.22 (m, 2 H), 5.61-5.65 (m, 1 H), 5.72-5.76
(m, 1 H); 13C NMR (CDCl3, 125.7 MHz) δ 4.9 (t′), 29.1 (t′), 32.0
(t′), 40.0 (t′), 46.5 (d′), 131.2 (d′), 133.1 (d′).
(b) 4-(2-Cyclopen ten -1-yl)-1-bu tyn e (22a). Aqueous NaOH
(2 N, 20 mL) was added to a stirred solution of [4-(2-
cyclopenten-1-yl)but-1-ynyl]trimethylsilane (1.00 g, 5.2 mmol)
in MeOH (30 mL), stirring was continued for 3 h, and the
mixture was then extracted with pentane. Evaporation of the
solvent at 1 atm (short Vigreux column) and flash chroma-
tography of the residue over silica gel (1 × 15 cm), using
pentane, gave 22a 30 (0.30 g, 49%) as a colorless oil: 13C NMR
(CDCl3, 100.6 MHz) δ 16.8 (t′), 29.4 (t′), 31.9 (t′), 34.6 (t′), 44.6
(d′), 68.0 (d′), 84.7 (s′), 130.9 (d′), 134.2 (d′).
Ack n ow led gm en t. We thank the Natural Sciences
and Engineering Research Council of Canada and
Merck Frosst for financial support. We thank H. Yang,
S. Ardelean, R. Subedi, and H. Cheng of this laboratory
for compounds 20a , 21a , 23a , and 24a , respectively.
cis-Octa h yd r o-1-m eth ylen ep en ta len e (22b). The general
thermal procedure for radical cyclization was followed, using
22a (40.0 mg, 0.33 mmol) in PhH (3 mL), stannane 1 (200 mg,
0.46 mmol) and AIBN (7 mg, 0.04 mmol) in PhH (7 mL, plus
2 mL as a rinse), an addition time of 5 h, and an arbitrary
reflux time of 3 h after the addition. After evaporation of the
solvent, CF3CO2H (0.2 mL) and THF (5 mL) were added, and
the mixture was stirred at room temperature for 3 h. The
general basic workup procedure was then followed, using
aqueous LiOH (1 M, 4 mL) and a reaction time of 3 h. Flash
Su p p or tin g In for m a tion Ava ila ble: NMR spectra of 1,
8, 10a , 20a , 20b, 21b, 3-(2-iodoethyl)cyclopentene, and [4-(2-
cyclopenten-1-yl)but-1-ynyl]trimethylsilane and H NMR spec-
tra that monitor the purification process for the experiments
of entries 1, 2, and 6 of Table 1. This material is available
free of charge via the Internet at http://pubs.acs.org.
1
J O010885C
(31) Gassman, P. G.; Valcho, J . J .; Proehl, G. S.; Cooper, C. F. J .
Am. Chem. Soc. 1980, 102, 6519-6526.
(32) Clive. D. L. J .; Subedi, R. J . Chem. Soc., Chem. Commun. 2000,
(29) This compound is reported, without experimental details, in
Curran, D. P.; Yu, H.; Liu, H. Tetrahedron 1994, 50, 7343-7366. We
prepared the iodide from the corresponding alcohol (Lee, C. C.; Wong,
E. W. C. Tetrahedron 1965, 21, 539-545) by treatment with Ph3P, I2,
and imidazole (cf. ref 25).
(30) Piers, E.; Chong, M. J .; Howard, M. Tetrahedron 1989, 45, 363-
380.
237-238.
(33) Clive. D. L. J .; Cheng, H. J . Chem. Soc., Chem. Commun. 2001,
605-606.
(34) Molander, G. A.; Harris, C. R. J . Org. Chem. 1997, 62, 7418-
7429.