The reaction of triphenylstannylcobaloxime with enynes under photochemical and thermal conditions

Article abstract of DOI:10.1016/S0022-328X(00)00550-7

Enynes having the 4-oxa-6-en-1-yne, 4-tosylaza-6-en-1-yne and 5-oxa-7-en-1-yne system, and 5,7-dioxa-l-octyne were reacted with triphenylstannylcobaloxime, which is a source of the triphenylstannyl radical and cobaloxime radical. The reaction pattern is different under photochemical and thermal conditions. Photochemical reaction gave the products formed by the addition of the triphenylstannyl radical to the acetylene group followed by the tandem addition of the intermediate vinyl radical to the intramolecular olefin. Thermal reaction gave triphenylstannyl-substitution products at the terminal position of the acetylene moiety. Thus, the photochemical reaction takes a free radical pathway, and the thermal reaction is proposed to take a single electron transfer mechanism.

Full text of DOI:10.1016/S0022-328X(00)00550-7

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 616 (2000) 89–95
The reaction of triphenylstannylcobaloxime with enynes under
photochemical and thermal conditions
Masaru Tada *, Yoshinobu Hanaoka
Department of Chemistry, Materials Research Laboratory for Bioscience and Photonics, Waseda Uni6ersity, Shinjuku, Tokyo 169-8555, Japan
Received 26 April 2000; received in revised form 21 June 2000; accepted 30 June 2000
Abstract
Enynes having the 4-oxa-6-en-1-yne, 4-tosylaza-6-en-1-yne and 5-oxa-7-en-1-yne system, and 5,7-dioxa-1-octyne were reacted
with triphenylstannylcobaloxime, which is a source of the triphenylstannyl radical and cobaloxime radical. The reaction pattern
is different under photochemical and thermal conditions. Photochemical reaction gave the products formed by the addition of the
triphenylstannyl radical to the acetylene group followed by the tandem addition of the intermediate vinyl radical to the
intramolecular olefin. Thermal reaction gave triphenylstannyl-substitution products at the terminal position of the acetylene
moiety. Thus, the photochemical reaction takes a free radical pathway, and the thermal reaction is proposed to take a single
electron transfer mechanism. © 2000 Elsevier Science B.V. All rights reserved.
Keywords: Stannyl-cobalt complex; Enyne; Triphenylstannyl radical; Tandem cyclization; Triphenylstannyl-acetylide
1. Introduction
4-oxa-hept-6-en-1-yne [1c,5], 4-tosylaza-hept-6-en-1-yne
[6], and diethyl 2-allyl-2-propynylmalonate [2,13b,14].
A heteroatom radical is usually generated from a
dichalcogenide [14,15] or a distannane [16] and more
conventionally by the combination of tributylstannane
and AIBN. We have reported that arylselenocobal-
oxime [17] and triphenylstannylcobaloxime [18]
Heteroatom free radicals such as chalcogen [1–4] or
stannyl radical [5–12] add to terminal acetylenes to
yield vinyl-chalcogenides or vinylstannyl derivatives,
respectively (Scheme 1(a)). Cyclization products are
obtained from enynes such as hept-6-en-1-yne [13],
(phenylseleno-
and
triphenylstannyl(pyridine)-bis-
dimethylglyoximatocobalt(III)) are good sources of the
arylseleno and arylstannyl radicals (Scheme 1(b)).
Triphenylstannylcobaloxime is a unique complex which
yields a pair of metal radicals of different character in
the cleavage of the metal–metal bond. On reaction of
the triphenylstannyl radical from triphenylstannylcoba-
loxime, the cobaloxime(II) species coexists in the reac-
tion system and may affect the reaction process to give
different products from those with stannanes.
In this paper, we compare the reactions between
triphenylstannylcobaloxime and some enynes under
photochemical and thermal conditions. Enynes 1–3
were selected because of the possible tandem cyclization
of the intermediate vinyl radical, and homopropargyl
ethers 4 and 5 were selected because of the possible
1,5-shift of the hydrogen activated by adjacent ether or
vinyl functions.
Scheme 1.
* Corresponding author. Fax: +81-3-5286-3237.
E-mail address: mtada@mn.waseda.ac.jp (M. Tada).
0022-328X/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00550-7

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M. Tada, Y. Hanaoka / Journal of Organometallic Chemistry 616 (2000) 89–95
in benzene or acetonitrile gave cyclized products 6–8 in
moderate yields as shown in Scheme 2 and Table 1.
The reactions of homopropargyl derivatives 4 and 5
were expected to give the products derived from in-
tramolecular 1,5-hydrogen transfer (Scheme 3). The
photoreactions, however, gave only the substitution
products 9 and 10 in poor yields after the prolonged
irradiation (Scheme 2 and Table 1). Moderate or low
yields of the addition products are mainly due to the
formation of phenylcobaloxime and the insoluble poly-
mers of diphenylstannylene units which show only the
signals due to the phenyl group in the 1H-NMR
spectrum.
1
Product 6 (6a/6b=2) shows twin peaks in the H-
NMR for every proton. The spectrum is characterized
by the double triplets (J=5.9 and 3.7) at l=4.56 and
4.67, and other double triplets (J=5.9 and 2.4) at
l=6.43 and 6.30 due to the endo-cyclic olefin. Two
ring methylenes give multiplets at l=2.74 and 3.00
(next to the ring olefin) and singlets at l=4.39 and
4.29 (next to the oxygen). Signal assignment was made
1
by H-1H COSY (500 MHz), and the E/Z ratio of 6a
and 6b was based on the NOE observation (300 MHz)
between the hydrogen of exo-cyclic olefin and the meth-
ylene next to the ring oxygen (E-isomer) or the methyl-
ene next to the ring olefin (Z-isomer).
Structure 7 was characterized by the typical pattern
of vinyl signals (3H) at l=5.1–5.7 region, the signals
of exo-olefin at l=6.10 (multiplet), and two ring meth-
ylene groups at l=3.56, 4.05, 4.19 and 4.13. The signal
Scheme 2.
Table 1
1
assignment was done by H-1H COSY and is shown in
Photoreaction of triphenylstannylcobaloxime with enynes
the Section 3. Structure 8 was deduced from the mech-
anistic similarity to the formation of 7 and the analysis
Enyne Solvent
Reaction time (h)
Product (yield/%)
1
1
of the H-NMR spectrum including H-1H COSY. Sig-
nals due to the endo-cyclic olefin protons appear at
l=5.67 (double triplet) and 5.77 (multiplet), and the
exo-cyclic olefin proton appears at l=6.15 (double
triplet). The methylene protons in the five-membered
ring appear at l=4.10 and 4.17 (double double
doublet).
1
1
2
2
3
3
4
5
14
15
Benzene a 22
6a b+6b b (38)
Complex mixture
7 (35)
7 (36)
8 (41)
8 (48)
9 (30)
10 (40)
16 (15)
CH3CN c
19
Benzene a 17
CH3CN c
21
Benzene a 47
CH3CN c
19
Benzene a 94
Benzene a 78
Benzene d 120
Benzene d 120
The formation processes of 6 and 7 are shown in
Scheme 4. These tandem processes are analogous to the
free radical cyclizations of enynes reported by Beckwith
and O’Shea [13a], Stork and Mock [13b], and Malacria
et al. [20]. The less hindered a-hydrogen (Ha) in H is
abstracted by the coexisting cobaloxime(II) species in
preference to the sterically hindered g-hydrogen (Hg).
17 (19)
a Enyne 1.0×10−1 mol l−1; Ph3Sn(4-t-butylpyridine)[Co] 1.0×
10−2 mol l−1
.
b A 2:1 mixture of 6a and 6b.
c Enyne 5.0×10−2 mol l−1; Ph3Sn(4-t-butylpyridine)[Co] 5.0×
10−3 mol l−1
.
d Enyne 1.0×10−2 mol l−1; Ph3Sn(4-t-butylpyridine)[Co] 1.0×
10−2 mol l−1
.
2. Results and discussion
Photolysis of triphenylstannylcobaloxime has been
known to generate a pair of triphenylstannyl and coba-
loxime radicals [18,19], and the photolysis of a 1:10
mixture of triphenylstannylcobaloxime and enynes 1–3
Scheme 3.

M. Tada, Y. Hanaoka / Journal of Organometallic Chemistry 616 (2000) 89–95
91
ucts from the reaction of triphenylstannyl-cobaloxime
are dienes, 3-oxa-5-(2-triphenylstannylmethylen)-cyclo-
hex-1-ene (6) (Scheme 4(c)).
Nativi and Taddei proposed the interaction between
the triphenylstannyl radical and an ether function [23].
This interaction with a homopropargyl ether function
in 4 and 5 (Scheme 3(A and B)) may prevent the
conformation C for the 1,5-hydrogen transfer from the
activated methylene to the vinyl radical as reported in a
few cases [24–28]. One of the plausible accounts for the
formation of 9 and 10 is that the addition of the
triphenylstannyl radical to the acetylene group is re-
versible and that the intermediate B (Scheme 3) is a
non-productive one. As a result only a slow thermal
reaction (described later) takes place after the pro-
longed reaction period (Table 1). Thus the photoreac-
tions of triphenylstannylcobaloxime are accounted for
by the radical process triggered by the addition of the
triphenylstannyl radical to the terminal acetylenes.
Next, triphenylstannylcobaloxime [18] was reacted
with enynes 1–5 in boiling acetonitrile (81°C) to com-
pare the reactivity under photochemical and thermal
conditions, and triphenylstannyl-substituted products
11–13, 9 and 10 were obtained as shown in Scheme 5
and Table 2. Similar thermal reactions in boiling ben-
zene were extremely slow and gave complex mixtures.
Structures 9–13 were unequivocally determined from
the displacement of the 1H-NMR signal due to the
terminal acetylenic hydrogen with the signals of the
triphenylstannyl group.
Scheme 4.
Under the thermal conditions phenylcobalaoxime
and a polymer of the diphenylstannyl residue were
formed in considerable amounts, and the yields of 9–13
remained at moderate or low figures (Table 2). These
by-products must originate from a process other than
the triphenylstannyl substitution of acetylenes, and its
mechanism is still ambiguous.
The photoreactions of enynes 14 and 15 (Fig. 1)
having a tosylaza-bridge show a poor but similar type
of photo-reaction with enynes 1–3, and the products 16
and 17 were obtained in low yields after a prolonged
irradiation in benzene (Scheme 2 and Table 1). In
acetonitrile, however, those enynes having the N-tosyl
Table 2
Thermal reaction of triphenylstannylcobaloxime with enynes a
Scheme 5.
Enyne
Reaction time (h)
Product (yield/%)
1
2
3
4
5
22
17
17
19
18
11 (33)
12 (23)
13 (16)
9 (46)
Similarly, the least hindered methyl hydrogen from the
intermediate F (R=CH3) is abstracted by coba-
loxime(II) to give product 7 (Scheme 4(d)) [21,22]. The
same type of reaction with a stannane terminates the
tandem cyclization by the hydrogen abstraction by H to
give a mono-ene product [13,14]. In contrast, the prod-
10 (36)
a Enyne 2.0×10−1 mol l−1; Ph3Sn(4-t-butyl-pyridine)[Co] 2.0×
10−2 mol l−1; solvent, dry acetonitrile.

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M. Tada, Y. Hanaoka / Journal of Organometallic Chemistry 616 (2000) 89–95
anion and cobaloxime(III) cation gives a (i-triphenyl-
stannyl)vinylcobaloxime (d) which decomposes into a
triphenylstannyl-acetylene and hydrocobaloxime (e).
This elimination step must be irreversible due to the
loss of hydridocobaloxime by the decomposition into
hydrogen and cobaloxime(II) (f) [29,30]. If the thermal
reaction involves (triphenylstannyl)vinyl radical as an
intermediate, it is difficult to explain the lack of tendem
addition products 6–8 from enynes 1–3, the solvent
effect, and the inhibitory effect by tosylamides.
Fig. 1. Enynes 14 and 15.
The intermediate (b-triphenylstannyl)vinylcobal-
oxime ((d) in Scheme 6) was not proven in the present
case but (b-phenylseleno)vinylcobaloxime is a major
product of the reaction of (phenylseleno)cobaloxime
with acetylenes [17]. We have no definite explanation of
this difference in the stability of the two kinds of
vinylcobaloximes. If the reactive species is a triphenyl-
stannyl cation other than the radical, the olefinic part
of the enyne is more susceptible to the stannyl cation to
give a different type of product.
There must be an efficient scavenging process in the
photochemical and thermal reactions between N-tosy-
lates (14 and 15) and the stannylcobaloxime in acetoni-
trile, a polar solvent. One of the reasonable accounts is
a preferential single electron transfer between triphenyl-
stannylcobaloxime and an N-tosyl group (Scheme 7).
Triphenylstannylcobaloxime seems to be a good elec-
tron donor, and an excited triphenylstannylcobaloxime
seems an even better electron donor in acetonitrile.
In conclusion, triphenystannylcobaloxime shows dif-
ferent reactivities toward the enynes under photochemi-
cal and thermal conditions. The reaction accompanies
the thermal decomposition of triphenylstannylcoba-
loxime to give phenylcobaloxime and the formation of
a polymer from diphenylstannylene units, and the mod-
erate yields of the products limit the synthetic utilities
of the present reactions. Nevertheless, it is noteworthy
that triphenylstannylcobaloxime can provide both stan-
nyl and cobalt free radicals in the photoreaction. The
photoreaction proceeds by the addition of a triphenyl-
stannyl radical to the terminal acetylene followed by
the tandem addition of the vinyl radical to an in-
tramolecular olefin and the termination by the hydro-
gen elimination by the coexisting cobaloxime(II)
radical. When the intramolecular olefinic group is not
located in the proper position to cause exo-5-trig cy-
clization, the tandem addition does not take place and
the slow thermal decomposition produces acetylene-
substituted products. On the other hand, the thermal
reaction of triphenylstannylcobaloxime with enynes
yields triphenylstannyl-acetylenes and can be accounted
for by a single electron transfer mechanism. No free
radical mechanism takes place under the thermal condi-
tions as seen in the case of the reactions of phenylse-
lenocobaloxime or tributylstannane with acetylenes.
Scheme 6.
Scheme 7.
group show no reactivity toward triphenystannylcoba-
loxime under both photochemical and thermal
conditions.
Tosylate 14 is not only inert to triphenylstannylcoba-
loxime but also inhibits the reaction of enyne 4 with the
stannylcobaloxime in acetonitrile. The ene and yne part
of 14 is unrelated to this inhibition because the addition
of a molar equivalent of N,N-diethyl-p-toluenesulfon-
amide to the thermal reaction system of 4 (0.20 mol
l
−1) reduced the yield of 9 from 46% to 7.1% under the
same conditions. These findings prompt us to speculate
the single electron transfer mechanism depicted in
Scheme 6 as one of the most probable reaction
mechanisms.
Processes (a)–(c) in Scheme 6 can take place in the
single solvent-cage formed partly from the acetylenes,
and the triphenylstannyl radical formed in step (b)
dissipates by an in-cage coupling (c) before the diffu-
sion from the solvent cage for the addition to un-
touched enynes. The coupling of the resulting vinyl

M. Tada, Y. Hanaoka / Journal of Organometallic Chemistry 616 (2000) 89–95
93
3. Experimental
3.3. General procedure for the photoreaction of
triphenylstannylcobaloxime with enynes
3.1. General
A mixture of triphenylstannylcobaloxime (2.0×10−4
moles) and one of the enynes (4.0×10−3 moles) in 20
ml of dry benzene was placed in two Pyrex reaction
vessels and deaerated in an ultrasonic bath with intro-
duction of argon. The photoreactions were monitored
by TLC analyses of aliquots of the reaction mixtures.
In the case of the photoreaction in acetonitrile, a mix-
ture of triphenylstannylcobaloxime (1.0×10−4 moles)
and one of the enynes (1.0×10−3 moles) in 20 ml of
dry acetonitrile was used due to the low solubility of
triphenylstannylcobaloxime at ambient temperature.
After irradiation for the period cited in Table 1, the
reaction mixtures were condensed in vacuo and the
residues were passed through a short column of Florisil
using dichloromethane to remove polar degradation
products. The eluates were subjected to preparative
TLC using the mixed solvent of hexane–ethyl acetate.
For the TLC separation of product 16 and 17, chloro-
form and the mixture of hexane–ethyl acetate (15:1)
were, respectively, used. Product 6 is an inseparable 2:1
mixture of the E- (6a) and Z-isomers (6b). All the
1H-NMR signals appear as a twin in 2:1 ratio. IR and
mass measurements were done with this mixture.
1H-NMR spectra were recorded on a JEOL Al-300
(300 MHz), and H-1H COSY and NOE measurement
1
were done using a JEOL JMN-500 (500 MHz) spec-
trometer. The measurements were done in deuteriochlo-
roform solutions containing TMS as an internal
standard, and chemical shifts and coupling constants
are recorded in l-values and Hertz, respectively. IR
spectra were recorded on a Horiba FT-710 spectrome-
ter in chloroform solution. FAB-mass spectra were
recorded on a JEOL DX-300 spectrometer using meta-
nitrobenzylalcohol or glycerol as a matrix medium. All
the spectra and elemental analyses were performed
using the facilities of the Materials Characterization
Central Laboratory of Waseda University. Photo-irra-
diations were done using a Rayonet RPR-100 photore-
actor equipped with 350 nm lamps. Dry benzene free of
thiophene and acetonitrile were dried over phosphorous
pentoxide followed by calcium hydride for the thermal
and photochemical reactions. Preparative TLC was per-
formed using 20×20×0.2 cm plates of silica gel
(Merck 60, PF254).
1
3.2. Starting materials
6: oil (a 2:1 mixture of 6a and 6b). 6a: H-NMR (300
MHz): 2.74 (2H, m), 4.39 (2H, s), 4.56 (1H, dt, J=5.9
Enynes 1–5 [1c, 31–33] and 14 [34] were prepared by
the reported methods and all the spectral data coin-
cided with the reported ones. Enyne 15 was prepared by
the same procedure for the preparation of enyne 14
starting from propargyl bromide and N-crotyl-p-
toluenesulfonamide.
and 3.7), 6.08 (1H, s), 6.43 (1H, dt, J=5.9 and 2.4),
7.30–7.42 (9H, m), 7.51–7.70 (6H, m). 6b: H-NMR
(300 MHz): 3.00 (2H, m), 4.29 (2H, s), 4.67 (1H, dt,
1
J=5.9 and 3.7), 6.09 (1H, s), 6.30 (1H, dt, J=5.9 and
2.4), 7.30–7.42 (9H, m), 7.51–7.70 (6H, m). IR (cm−1
)
(6a+6b): 1653, 1481, 1430, 1075. High-resolution mass
(FAB): m/z=445.0651. Calc. for [C24H22O118Sn+H+]:
m/z=445.0614.
1
15: m.p. 63.0–64.0. H-NMR (300 MHz): 1.69 (3H,
d, J=6.4), 1.99 (1H, t, J=2.2), 2.42 (3H, s), 3.75 (2H,
d, J=6.6), 4.08 (2H, d, J=2.2), 5.36 (1H, dq, J=15.1
and 6.4), 5.70 (1H, dt, J=15.1 and 6.6), 7.29 (2H, d,
J=8.1), 7.72 (2H, d, J=8.1). EI-mass(70 eV): m/z=
263(M+, 23%). IR (cm−1): 3307, 1559, 1436, 1347,
1162, 1092. Anal. Found: C, 63.80; H, 6.39; N, 5.40.
Calc. for C14H17NO2Sn: C, 63.85; H, 6.51; N, 5.32%.
7: oil. 1H-NMR (300 MHz): 3.43 (1H, dt, J=8.5 and
8.5, Ha), 3.56 (1H, dd, J=8.5 and 8.5, Hb), 4.05 (1H,
ddd, J=14.0, 2.4 and 2.4, Hc), 4.19 (1H, ddd, J=14.0,
2.4 and 0.7, Hc), 5.15–5.18 (2H, m, Hdd%), 5.69 (1H, m,
He), 6.10 (1H, dt, J=2.4 and 2.4, Hf), 7.32–7.40 (9H,
m), 7.50–7.58 (6H, m). IR (cm−1): 1635, 1481, 1430,
1075. High-resolution mass (FAB): m/z=459.0793.
Calc. for [C25H24O118Sn+H+]: m/z=459.0791 (the
NMR assignment of 7 is shown in Fig. 2).
8: m.p. 109.0–110.0°C (hexane). 1H-NMR (300
MHz): 1.57–1.69 (2H, m), 1.78–1.99 (2H, m), 2.10–
2.19 (1H, m), 4.10 (1H, ddd, J=14.0, 2.6 and 0.9), 4.17
(1H, ddd, J=14.0, 1.9 and 1.9), 4.23–4.29 (1H,dt,
J=9.0 and 3.0), 5.67 (1H, dt, J=9.9 and 1.9), 5.77
(1H, m), 6.13–6.17 (1H, dt, J=2.5 and 2.5), 7.32–7.40
(9H, m), 7.51–7.58 (6H, m). IR (cm−1): 1624, 1481,
1430, 1075. Anal. Found: C, 66.72; H, 5.51. Calc. for
C27H26OSn: C, 66.84; H, 5.40%.
9: oil. 1H-NMR (300 MHz): 2.67 (2H, t, J=7.0),
3.34 (3H, s), 3.73 (2H, t, J=7.0), 4.66 (2H, s), 7.32–
Fig. 2. The NMR assignment of 7.

94
M. Tada, Y. Hanaoka / Journal of Organometallic Chemistry 616 (2000) 89–95
11: oil. 1H-NMR (300 MHz): 4.14 (2H, diff.d, J=5.8),
4.28 (2H, s), 5.22 (1H, diff.d, J=10.3), 5.32 (1H, diff.d,
J=17.2), 5.91 (1H, ddt, J=17.2, 10.3 and 5.8), 7.34–
7.47 (9H, m), 7.58–7.68 (6H, m). IR (cm−1): 2156, 1650,
1481, 1430, 1260, 1076. High-resolution mass (FAB):
m/z=447.0744. Calc. for [C24H22O120Sn+H+]: m/z=
447.0771.
12: oil. 1H-NMR (300 MHz): 1.71 (3H, br.d, J=6.4),
4.06 (2H, d, J=6.3), 4.25 (2H, s), 5.60 (1H, dt, J=15.2
and 6.3), 5.76 (1H, dq, J=15.2 and 6.4), 7.36–7.47 (9H,
m), 7.57–7.70 (6H, m). IR (cm−1): 2155, 1482, 1431,
1350, 1092. FAB-mass: m/z=382 and 381(13 and 5.4%,
M+–Ph), 351 and 349(35 and 100%, Ph3Sn+), no
molecular peak.
Fig. 3. The NMR assignment of 17.
7.49 (9H, m), 7.60–7.70 (6H, m). IR (cm−1): 2120, 1643,
1481, 1431, 1257 1076. High-resolution mass (FAB):
m/z=465.0877. Calc. for [C24H24O1220Sn+H+]: m/z=
465.0832.
13: oil. 1H-NMR (300 MHz): 1.48–2.10 (6H, m),
4.15–4.25 (1H, m), 4.33 (2H, s), 5.83–5.92 (2H, m),
7.35–7.47 (9H, m), 7.75–7.70 (6H, m). IR (cm−1): 2155,
1650, 1482, 1431, 1346, 1077. FAB-mass: m/z=487 and
485 (1.0 and 2.1%, [M+H+]), 351 and 349 (68 and 100%,
Ph3Sn+), 197 and 195 (51 and 45%, PhSn+), no molec-
ular peak.
10: oil. 1H-NMR (300 MHz): 2.66 (2H, t, J=7.2), 3.65
(2H, t, J=7.2), 4.03 (2H, ddd, J=5.7, 1,7 and 1.7), 5.17
(1H, dtd, J=10.3, 1.5 and 1.4), 5.29 (1H, dtd, J=17.2,
1.5 and 1.4), 5.90 (1H, m), 7.31–7.44 (9H, m), 7.59–7.66
(6H, m). IR (cm−1): 2157, 1646, 1482, 1431, 1097.
FAB-mass: m/z=383 and 381(17 and 10%, M+–Ph),
351, 349(100 and 78%, Ph3Sn+), no molecular peak.
1
16: oil. H-NMR (300 MHz): 2.22 (3H, s), 2.58–2.65
(2H, m), 4.12 (2H, s), 4.89 (1H, dt, J=8.0 and 3.6), 5.92
(1H, s), 6.66 (1H, dt, J=8.0 and 2.0), 7.18 (2H, d,
J=8.0), 7.68 (2H, d, J=8.0), 7.26–7.78 (15H, m). IR
(cm−1): 1652, 1645, 1446, 1429, 1164. High-resolution
mass (FAB): m/z=600.1059. Calc. for [C31H29NO2S-
120Sn+H+]: m/z=600.1019.
Acknowledgements
This work was supported by the Annual Project
Organized by Waseda University and the Grant-in-Aid
for Science Research Administered by the Minister of
Education, Culture, and Sports of Japan.
1
17: powder. H-NMR (300 MHz): 2.42 (3H, s), 2.76
(1H, dd, J=9.2 and 9.2, Ha), 3.41 (2H, m, Hbb%), 3.63
(1H, dd, J=9.2 and 7.7, Hc), 3.76 (1H, m, Hc%), 5.16
(1H, dd, J=16.7 and 0.7, Hd), 5.18 (1H, dd, J=10.3 and
0.7, He), 5.52 (1H, ddd, J=16.7, 10.3 and 9.2, Hf),
5.98–6.07 (1H, dt, J=2.7 and 2.7, Hg), 7.18 (2H, d,
J=8.1), 7.33–7.75 (17H, m). IR (cm−1): 1624, 1599,
1481, 1430, 1348, 1163. High-resolution mass (FAB):
m/z=614.1135. Calc. for [C32H31NO2S120Sn+H+]: m/
z=614.1176 (the NMR assignment of 17 is shown in
Fig. 3).
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