Stereoselective hydrostannation of substituted alkynes initiated by triethylborane and reactivity of bulky triorganotin hydrides

Article abstract of DOI:10.1016/j.jorganchem.2005.11.020

This paper reports the results obtained in a study on the radical hydrostannation of mono- and disubstituted alkynes with bulky triorganotin hydrides using triethylborane as initiator. The addition of trineophyl- (1), tris[(phenyldimethylsilyl)methyl]- (2), and 9-tripticyldimethyltin (3) hydride to eight alkynes was carried out at room temperature leading to vinylstannanes in good to excellent yields and, mostly, with complete stereoselectivity. The results obtained in a study on the relative reactivity of trineophyl- (1), tris[(phenyldimethylsilyl)methyl]- (2), 9-triptycyldimethyltin (3) hydrides, and tri-n-butyltin hydride (29) using the radical reactions between these hydrides and 6-bromo-1-hexene (28) are also reported. Full ¹H-, ¹³C-, and ¹¹⁹Sn NMR characteristics are included.

Full text of DOI:10.1016/j.jorganchem.2005.11.020

Journal of Organometallic Chemistry 691 (2006) 1085–1091
www.elsevier.com/locate/jorganchem
Stereoselective hydrostannation of substituted alkynes initiated
by triethylborane and reactivity of bulky triorganotin hydrides
a
a
a,b
a
´
´
´
˜
Marıa B. Faraoni , Veronica I. Dodero , Liliana C. Koll , Adriana E. Zuniga ,
,c
a,b,
*
*
´
Terence N. Mitchell , Julio C. Podesta
a
Instituto de Investigaciones en Quı´mica Orga´nica, Departamento de Quı´mica, Universidad Nacional del Sur,
Avenida Alem 1253, 8000 Bahı´a Blanca, Argentina
b
CONICET, Argentina
Fachbereich Chemie, der Universita¨t Dortmund, D-44221, Germany
c
Received 24 October 2005; received in revised form 4 November 2005; accepted 5 November 2005
Available online 20 December 2005
Abstract
This paper reports the results obtained in a study on the radical hydrostannation of mono- and disubstituted alkynes with bulky
triorganotin hydrides using triethylborane as initiator. The addition of trineophyl- (1), tris[(phenyldimethylsilyl)methyl]- (2), and 9-tript-
icyldimethyltin (3) hydride to eight alkynes was carried out at room temperature leading to vinylstannanes in good to excellent yields
and, mostly, with complete stereoselectivity. The results obtained in a study on the relative reactivity of trineophyl- (1), tris[(phenyldi-
methylsilyl)methyl]- (2), 9-triptycyldimethyltin (3) hydrides, and tri-n-butyltin hydride (29) using the radical reactions between these
1
hydrides and 6-bromo-1-hexene (28) are also reported. Full H-, 13C-, and 119Sn NMR characteristics are included.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Radical hydrostannations; Triethylborane; Vinylstannanes; Stereoselectivity; Bulky organotin hydrides reactivity
1. Introduction
organotin moieties with neophyl, (phenyldimethylsi-
lyl)methyl, and 9-triptycyl ligands attached to the tin atom,
via radical hydrostannation using azobisisobutyronitrile
(AIBN) as a radical initiator [3f,3g,3h,3i].
In order to compare the stereoselectivities that can be
achieved using triethylborane as initiator with those
obtained using AIBN, we now considered it convenient
to carry out a study on the radical addition of the bulky
trineophyl- (1), tris[(phenyldimethylsilyl)methyl]- (2), and
9-triptycyldimethyltin (3) hydrides to alkynes mediated
by triethylborane. We also considered it of interest to carry
out a study of the relative reactivity of these hydrides under
radical conditions.
Organotin hydrides are versatile reagents for organic
synthesis. They have found wide application not only as
reducing reagents but also as intermediates in the genera-
tion of carbon–carbon bonds, and for the preparation of
vinylstannanes, invaluable starting materials for cross-
coupling reactions [1]. The radical addition of organotin
hydrides to alkynes induced by triethylborane reported
by Oshima and co-workers permits stereoselective hydro-
stannations at room temperature and even at low temper-
atures such as ꢀ78 ꢁC [2]. In previous studies we have
shown that the size of the organic ligands attached to the
tin atom affects not only the reactivity but also the stereose-
lectivity of the reactions of these compounds [3]. These
studies included the synthesis of vinylstannanes containing
2. Results and discussion
The addition of trineophyl- (1), tris[(phenyldimethylsi-
lyl)methyl]- (2), and 9-triptycyldimethyltin hydride (3) to
phenylacetylene, propargyl alcohol, methyl propiolate,
*
Corresponding author. Tel.: +54 291 4595101; fax: +54 291 4595187.
´
E-mail address: jpodesta@uns.edu.ar (J.C. Podesta).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.11.020

1086
M.B. Faraoni et al. / Journal of Organometallic Chemistry 691 (2006) 1085–1091
3-butyn-2-one, diphenylacetylene, methyl and ethyl phenyl-
propiolates, and dimethyl acetylenedicarboxylate was car-
ried out at room temperature, in toluene, under a
nitrogen atmosphere, using an organotin hydride/alkyne
ratio of 1:1, and 0.1 equiv. of triethylborane. Taking into
account previous work [3f,3g,3h,3i], we considered it possi-
ble that under radical conditions the main products of
these reactions should be those corresponding to an anti-
addition of the tin hydride, Z(a) and Z(b), as shown in
the scheme included in Table 1. The results obtained are
summarized in Table 1.
13C- and 1H NMR characteristics of the new organotins 5,
10, 15, 16, 20, 22, 24, 26, are summarized in Tables 2 and 3.
The Z stereochemistry of adducts 5–8, 10–24, and 26–27
was assigned taking into account that the observed
1
1
3J(119Sn, H) coupling constants in the H NMR spectra
were mostly well over 100 Hz, which indicate the existence
of trans H–C–C–Sn linkages in these compounds. On the
3
1
other hand, the observed J(119Sn, H) coupling constants
for compounds 4 (64.0 Hz [3f]) and 25 (85.2 Hz [3f]), clearly
indicate the existence of a cis H–C–C–Sn linkage in these
adducts. It should be noted that although we were not able
1
The NMR characteristics of compounds 4, 7, 11, 17, 19,
25 [3f], 8, 12, 23 [3g], 14 [3h], and 6, 13, 18, 21, 27 [3i], have
been reported in earlier publications of our research group.
to obtain compound 9 in a pure state, in the H NMR of
the crude products it is possible to observe the coupling
3
1
3
1
constants J(119Sn, H)trans 151.0 Hz and J(119Sn, H)cis
Table 1
Trineophyl- (1), tris(phenyldimethylsilylmethyl)- (2), and 9-tripticyldimethyltin hydride (3) radical additions to substituted alkynes
R1
SnR3
R2
R1
R2R'Sn
Z(anti,
H
R2
)
R1
R2
H
)
Et3B
+
R1
R2
+
+
R2R'SnH
H
R2R'Sn
Z (anti, α)
E(syn,
R= Me; R'= Tp =Triptycyl
=
Me Me
M
R= R': M= C= Neophyl (PhMe2CCH2 ) = Nph
R =R': M= Si = (Phenyldimethylsilyl)methyl =SiCH2
Ph
CH2
Entry No.
Compound No.
R2R0
R1
R2
Time (h)
Z(b) (%)
Z(a) (%)
E(b) (%)
Yielda (%)
119Snb (ppm)
1
2
3
4
5
4
Nph
H
H
H
H
H
Ph
Ph
Ph
CH2OH
CH2OH
1
3
1
3
2
–
–
–
–
–
100
–
–
–
–
100
91
98
64
55e
ꢀ93.7
ꢀ34.4
ꢀ76.9
ꢀ97.5
8: ꢀ40.4
9: ꢀ37.8
ꢀ78.9
ꢀ92.4
ꢀ37.3
ꢀ75.1
ꢀ89.0f
ꢀ37.2
ꢀ74.2
ꢀ89.0
–
ꢀ66.9
ꢀ81.7
ꢀ21.0
ꢀ64.8
ꢀ80.8
ꢀ23.7
ꢀ66.3
ꢀ80.7
ꢀ17.1
ꢀ58.4
5
SiCH2
TpMe2
Nph
100
100
100
67 (8)
6
7
8 and 9
SiCH2
33 (9)c,d
6
7
8
10
11
12
13
14
15
16
17
–
18
19
20
21
22
23
24
25
26
27
TpMe2
Nph
SiCH2
TpMe2
Nph
SiCH2
TpMe2
Nph
SiCH2
TpMe2
Nph
SiCH2
TpMe2
Nph
SiCH2
TpMe2
Nph
H
H
H
H
H
H
H
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
CH2OH
COOMe
COOMe
COOMe
COMe
COMe
COMe
Ph
1
1
2
1.5
3f
3
24
24
24
1
5
2
2
1
2
2
24
1
2
100
100
100
100
100f
100
–
–
–
–
–
–
–
100d
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
50
100
93
9
98
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
a
79f
100
74
100h
–
40
g
Ph
Ph
100h
100
100
100
100
100
100
–
63
87
85
83
86
92
53
90
100
73
COOMe
COOMe
COOMe
COOEt
COOEt
COOEt
COOMe
COOMe
COOMe
COOMe
COOMe
COOMe
–
–
–
100
–
–
SiCH2
TpMe2
100h
100h
Yields of products isolated from the column chromatography.
In CDCl3; in ppm with respect to Me4Sn.
From the 1H- and 119Sn NMR of the crude products mixture.
In this case isomer a.
b
c
d
e
f
There is some decomposition during purification and compound 9 could not be separated pure.
From [3h].
g
h
No adduct formed.
In these cases Z(b) = Z(a).

M.B. Faraoni et al. / Journal of Organometallic Chemistry 691 (2006) 1085–1091
1087
Table 2
13C NMR data of vinyltin adducts 5, 10, 15, 16, 20, 22, 24, 26a
R1
R2
R2R'Sn
C
1
C
2
H
b
No.
R2R0
R1
R2
C(1) [1J(Sn,C)]
C(2) [2J(Sn,C)]
R1c [2J(Sn,C)]
R2c [3J(Sn,C)]
Other signals
d
e
f
5
10
15
16
20
22
24
26
a
SiCH2
TpMe2
SiCH2
TpMe2
SiCH2
Nph
H
H
H
COMe
Ph
Ph
Ph
COOMe
Ph
134.64 (333.9)
129.70 (341.1)
130.82 (342.7)
156.11 (325.2)
140.02 (390.1)
141.72 (304.9)
139.59 (nd)
146.44 (25.4)
144.84 (31.3)
158.56 (41.8)
139.0 (30.4)
154.60 (11.0)
152.30 (7.3)
155.61 (27.2)
134.29 (29.4)
–
–
–
140.37 (30.6)
64.49 (39.8)
197.51 (26.2)
–
170.10 (40.5)
171.96 (35.8)
171.32 (38.6)
171.68 (43.8)
CH2OH
COMe
H
COOMe
COOEt
COOEt
COOMe
g
h
i
198.0 (23.0)
141.23 (22.2)
151.79 (32.7)
138.45 (23.6)
167.00 (20.4)
j
TpMe2
SiCH2
k
162.38 (358.4)
In CDCl3; chemical shifts, d, in ppm with respect to TMS; nJ(119Sn, 13C) coupling constants, in Hz (in brackets); nd = not determined.
R2R0 = SiCH2 = tris(phenyldimethylsilylmethyl); R2R0 = TpMe2 = triptycyldimethyl.
b
c
d
e
f
Chemical shifts of the carbons attached to C(1) and C(2).
ꢀ2.82 (258.3) (51.7); ꢀ0.06 (13.0) (51.9); 127.05; 127,55; 127,81; 128.09; 128.55; 133.22; 141.21 (20.5).
ꢀ4.67 (342.2); 53.30 (nd); 54.93; 123.88; 124.62; 124.66; 125.44 (30.8); 148.17; 148.58.
ꢀ2.49 (279.1) (48.5); 0.20 (13.9) (52.9); 30.09; 127.51; 128.44; 133.29; 141.62 (20.8).
g
h
i
ꢀ6.58 (nd); 28.68; 29.31; 54.0 (nd); 123.04; 123.72; 123.75; 124.38 (29.7); 147.50; 149.91.
ꢀ1.28 (272.2) (48.6); 0.00 (13.0) (51.8); 51.58; 127.53; 128.22; 128.35; 128.52; 133.24; 137.85 (22.1).
14.30; 32.40 (32.7); 33.41 (336.9); 37.96 (18.5); 60.66; 125.25; 125.35; 127.85; 128.05; 128.28; 128.34; 138.67 (17.5).
ꢀ2.62 (361.3); 11.76; 54.78; 57.21 (nd); 60.60; 123.58; 124.31; 124.67; 126.19 (32.3); 128.17; 128.37; 128.86; 147.60; 147.68.
ꢀ1.38 (291.7) (49.1); ꢀ0.08 (14.8) (53.1); 51.72; 51.89; 127.46; 128.61; 133.27; 141.16 (21.2).
j
k
Table 3
1H NMR data of vinyltin compounds 5, 10, 15, 16, 20, 22, 24, 26
No.
Chemical shifts (d, in ppm)a
5
ꢀ0.07 [s, 6H, 2J(Sn,H) 75.8]; 0.26 (s, 18H); 6.14 [d, 1H, 3J(H,H) 14.0; 2J(Sn,H) 68.0]; 7.17–7.50 (m, 20H); 7.53 [d, 1H, 3J(H,H) 14.0;
3J(Sn,H) 160.0]
10
15
16
0.65 [s, 6H, 2J(Sn,H) 57.0]; 4.41 (2H); 5.29 (s, 1H); 6.32 [dt, 1H, 3J(H,H) 12.9, 4J(Sn,H) 1.8, 2J(Sn,H) 80.5]; 6.68 [dt, 1H, 3J(H,H) 12.9,
3J(H,H) 4.2, 3J(Sn,H) 126.6]; 6.82–7.40 (m, 12H)
0.01 [s, 6H, 2J(Sn,H) 75.0]; 0.20 (s, 18H); 2.09 (s, 3H); 6.86 (d, 1H, 3J(H,H) 12.0; 2J(Sn,H) 86.0]; 6.91 [d, 1H, 3J(H,H) 12.0, 3J(Sn,H) 162.0];
7.28–7.43 (m, 15H)
0.67 [s, 6H, 2J(Sn,H) 57.0]; 2.37 (s, 3H); 5.30 (s, 1H); 6.05 [d, 1H, 2J(H,H) 1.0, 2J(Sn,H) 66.4]; 6.74 [d, 1H, 2J(H,H) 1.0, 3J(Sn,H) 141.0];
6.85–7.38 (m, 12H)
20
22
24
26
0.03 [s, 6H, 2J(Sn,H) 76.0]; 0.25 (s, 18H); 3.71 (s, 3H); 7.24–7.48 (m, 20H); 8.44 [s, 1H, 3J(Sn,H) 122.0];
1.04 (s, 18H); 1.09 [s, 6H, 2J(Sn,H) 53.0]; 1.27 [t, 3H, 3J(H,H) 7.0]; 4.14 [q, 2H, 3J(H,H) 7.0]; 7.01–7.27 (m, 20H); 8.14 [s, 1H, 3J(Sn,H) 107.8]
0.00 [t, 3H, 3J(H,H) 7.2]; 0.67 [s, 6H, 2J(Sn,H) 54.2]; 3.33 [q, 2H, 3J(H,H) 7.2]; 5.49 (s, 1H); 6.95–7.77 (m, 17H); 8.73 [s, 1H, 3J(Sn,H) 122.4]
0.00 [s, 6H, 2J(Sn,H) 78.6]; 0.07 (s, 18H); 3.42 (s, 3H); 3.62 (s, 3H); 6.43 [s, 1H, 3J(Sn,H) 100.0]; 7.08–7.51 (m, 15H)
Multiplicity and J values in parentheses.
nJ(119Sn, 1H) coupling constants in Hz.
a
In CDCl3.
73.5 Hz corresponding to the a stereoisomer. These struc-
(entries 2–13, 15–21, and 23–24) the main (entry 5) or sole
products are those with Z(b) or Z(a) (entry 12) configura-
tion, i.e., the products resulting from an anti-attack.
The formation of the E-adducts 4 and 25, entries 1 and
22, could be explained by taking into account that the
known isomerization of the initially formed kinetic Z-prod-
ucts by further addition/elimination of the stannyl radical
would lead to the thermodynamically more stable E-vinylst-
annanes [4,5]. On the other hand, the formation of the Z-
vinylstannanes has been explained by considering that in
the equilibrium mixture of the conformers corresponding
to the intermediate alkyl radicals – the products of the addi-
tion of a second organotin radical – the conformers that
1
tures were confirmed by other 13C- and H NMR data.
In Table 1 it can be seen that only in the case of the reac-
tion between diphenylethyne and tris[(phenyldimethylsi-
lyl)methyl]tin hydride (2) (entry 14) could we not detect
any reaction product after 24 h. The results summarized
in Table 1 clearly demonstrate the high regio- and stereose-
lectivities that can be obtained in these radical hydrostan-
nations using bulky organotin hydrides. Thus, the
additions of hydrides 1, 2, and 3 to mono- and disubsti-
tuted alkynes (Table 1, entries 1–24) lead in 22 out of 23
cases to one diastereoisomer and in just one case -entry
5- to a mixture of two stereoisomers. Also in 21 cases

1088
M.B. Faraoni et al. / Journal of Organometallic Chemistry 691 (2006) 1085–1091
lead via anti-elimination of the organotin radical to the
Z-vinylstannanes are present in higher concentration. This
has been ascribed to the favorable interaction between
the tin atom and the neighbouring groups that predomi-
nates over the opposing effect of greater steric hindrance
[5].
These results clearly demonstrate that, contrary to what
has previously been stated [4,6,7], it is possible to carry out
stereoselective radical hydrostannations of alkynes using
organotin hydrides. Thus, excellent stereoselectivities could
be achieved at room temperature using triethylborane as
radical initiator and organotin hydrides with bulky organic
ligands such as 1, 2, and 3.
AIBN
In
In = Me2CCN
+Bu3Sn
In +Bu3SnH
InH
29
Br
+
Bu3SnBr
+
Bu3Sn
I
28
31
30
29
+
+
II
III
29
As for the radical initiator, the results obtained show
that, generally speaking, there are no significant differences
in the stereoselectivities and the yields obtained using either
AIBN or triethylborane. However, in some cases we have
found some differences. Thus, whereas in the case of the
addition of trineophyltin hydride (1) to methyl propiolate
and 3-butyn-2-one the reactions initiated by AIBN lead
to mixtures of two adducts [3f,3h], the additions to the
same substrates mediated by triethylborane (Table 1,
entries 7 and 10) lead to just one stereoisomer. Also,
whereas we could not detect any adduct in the reaction
of triptycyldimethyltin hydride (2) with propargyl alcohol
and 3-butyn-2-one initiated by AIBN [3i], the hydrostanna-
tion of the same substrates with 2 mediated by triethylbo-
rane takes place smoothly to give one stereoisomer (Table
1, entries 6 and 12).
Taking into account the synthetic importance of the tin
hydrides with bulky organic ligands, we considered it of
interest to determine the relative reactivities of trineophyl-
(1), tris[(phenyldimethylsilyl)methyl]- (2), and 9-triptycyl-
dimethyltin hydride (3). In order to compare the relative
reactivity of organotin hydrides, we had in previous studies
used the reaction between the hydrides and carbon tetra-
chloride. We measured the time required for the hydrides
to react completely at a known concentration in carbon tet-
rachloride (0.0077 M). These reactions were followed by IR
spectroscopy by observing the disappearance of the Sn–H
absorption ([3e], and references therein cited). We now con-
sidered it possible to achieve a better approximation to the
estimation of the relative reactivities of the organotin
hydrides by studying the composition of the mixture of
products resulting from their reaction with 6-bromo-1-hex-
ene (28) under radical conditions. Thus, it is known that
the free radical reaction between 28 and tributyltin hydride
(29) leads to a mixture of three compounds: 1-hexene (31),
methylcyclopentane (32), and cyclohexane (33), as shown
in Scheme 1 [8].
32
33
Scheme 1. Reaction of 6-bromo-1-hexene with tributyltin hydride under
free radical conditions.
icals II and III is that they are irreversible at the working
temperatures (ꢀ80 to 120 ꢁC) [9].
Taking into account the previous discussion, we carried
out a study of the reaction of 6-bromo-1-hexene (28) with
trineophyl- (1), tris[(phenyldimethylsilyl)methyl]- (2) [3g],
and 9-triptycyldimethyltin hydride (3) [3i], and also tribu-
tyltin hydride (29). The reactions were carried out using
three concentrations of the hydrides (0.1, 0.3 and 0.5 M)
in toluene, at 110 ꢁC, during 3 h and in the presence of cat-
alytic amounts of AIBN. The relative ratios of the products
were determined by GC–MS analysis. The results obtained
are summarized in Table 4.
These results indicate that at 0.1 M concentration, the
reactivity of hydrides 1 and 2 is almost the same as that
of tributyltin hydride (29), and that these three hydrides
undergo hydrogen abstraction by the 5-hexenyl radical (I)
about twice as fast as does hydride 3. Also, while the yield
of the cyclization products (32 + 33) obtained using
hydride 3 reach 93%, the yields obtained using hydrides
29, 1, and 2 are around 83%. The latter would confirm that
triptycyldimethyltin hydride (3) is less reactive than the
others because the slower hydrogen abstraction rate by
the radical I gives more time for the cyclization to give II
and III.
Using higher concentrations (0.3 and 0.5 M) it can be
seen that, as expected, all four hydrides undergo faster
hydrogen abstraction. However, it should be noted that
while the increase of the concentration from 0.3 to 0.5 M
in the case of hydrides 29 and 1 leads to an increase in
the rate of hydrogen abstraction, in the case of hydrides
2 and 3 the rates remain almost constant as shown by the
amounts of open chain (31) and cyclization products
(32 + 33) obtained for both concentrations.
The 5-hexenyl radical (I) has been used as a radical
probe due to its rapid rate of cyclization (1.3 · 105 sꢀ1) to
the cyclopentylmethyl radical (II) and the cyclohexyl radi-
cal (III) [9]. The less thermodynamically stable radical II is
rapidly formed via a non-symmetrical transition state more
sterically favorable for the formation of the 5 membered
ring. A characteristic feature of the cyclizations to give rad-
From these results it is possible to conclude that the
decreasing order for the rate of the hydrogen abstraction
step from these hydrides to radical I is:

M.B. Faraoni et al. / Journal of Organometallic Chemistry 691 (2006) 1085–1091
1089
Table 4
Radical reactions of 6-bromo-1-hexene with triorganotin hydrides 1, 2, 3, and 29
R3SnH
Br
+
R3SnBr
+
+
AIBN / 110 ºC
30
28
31
Toluene
32
33
R3SnH
31 (%)
32 (%)
33 (%)
30 (%)a
Concentration: 0.1 M
Bu3SnH (29)
16
17
17
7
78
76
78
88
6
7
5
5
95
94
93
99
Neoph3SnH (1)b
(PhSiMe2CH2)3SnH (2)
TripMe2SnH (3)b
Concentration: 0.3 M
Bu3SnH (29)
Neoph3SnH (1)
(PhSiMe2CH2)3SnH (2)
TripMe2SnH (3)
29
26
23
20
67
70
74
75
4
4
3
5
96
95
97
94
Concentration: 0.5 M
Bu3SnH (29)
Neoph3SnH (1)
(PhSiMe2CH2)3SnH (2)
TripMe2SnH (3)
48
37
22
21
49
59
72
72
3
4
6
7
98
98
96
97
Trip = Triptycyl.
a
Isolated triorganotin bromide.
Neoph = Neophyl = PhCMe2CH2.
b
3.2. Addition of triorganotin hydrides 1–3 to substituted
alkynes under radical conditions
Bu3SnH > Neoph3SnH > ðPhSiMe2CH2Þ3SnH
> TripMe2SnH
The results obtained using a 0.5 M concentration could
indicate that tributyltin hydride (29) would undergo hydro-
gen abstraction 1.3 times faster than hydride 1, 2.2 times
faster than hydride 2, and 2.3 times faster than hydride 3.
These results also reflect the great effect upon the reactivity
obtained by for example replacing one small organic ligand
such as the methyl group of the trimethyltin hydride by the
bulkier tripticyl ligand.
All the reactions were carried out following the same
procedure. One experiment is described in detail in order
to illustrate the methods used.
To a solution of propargyl alcohol (0.047 g, 0.80 mmol)
and tin hydride 3 (0.340 g, 0.80 mmol) in dry toluene
(3 mL) under nitrogen, was added triethylborane
(0.080 mmol, 0.080 mL of a 1 M solution in hexane), and
the mixture was stirred for 1 h at room temperature. The
solvent was then distilled off under reduced pressure. The
119Sn NMR spectrum of the product showed that it
consisted of only one compound: (Z)-3-triptycyldimethyl-
stannyl-2-propen-1-ol (10), peak at ꢀ78.9 ppm. Column
chromatography (silica gel 60) of the crude product gave
compound 10 pure (0.184 g, 0.40 mmol, 50%) in the frac-
tion eluted with hexane–diethyl ether (96:4).
3. Experimental
3.1. General methods
NMR spectra were obtained using a Bruker ARX 300
instrument. Mass spectra were obtained using a Finnigan
MAT Model 8230 at Dortmund University (Germany).
Infrared spectra were recorded with a Nicolet Nexus FT
spectrometer. Elemental analyses (C, H) were performed
at Dortmund University. All the solvents and reagents used
were analytical reagent grade. Trineophyl- (1) [10], tris
[(phenyldimethylsilyl)methyl]- (2) [3g] and 9-triptycyldi-
methyltin- (3) [3i] hydrides were prepared as described pre-
viously. Phenylacetylene, diphenylacetylene, propiolic acid,
phenylpropiolic acid, acetylenedicarboxylic acid, propargyl
alcohol, 3-butyn-2-one, and triethylborane were purchased
and purified by common procedures before use. The esters
of the acids were obtained following known techniques
[11].
3.3. Reaction of 6-bromo-1-hexene (28) with triorganotin
hydrides (1–3, 29)
All the reactions were carried out following the same
procedure. One experiment is described in detail in order
to illustrate the methods used.
To a 0.1 M solution of tin hydride 3 (0.20 g, 0.50 mmol) in
dry toluene (5 mL) under argon was added 6-bromo-1-hex-
ene (0.081 g, 0.50 mmol) and AIBN as a catalyst. The mix-
ture was heated under reflux for 3 h. A solution of volatile
compounds in toluene was obtained by distillation. Reaction
products were identified by GC–MS in a Hewlett–Packard

1090
M.B. Faraoni et al. / Journal of Organometallic Chemistry 691 (2006) 1085–1091
CGL-Ms 6890/5972 (capillary column HP5-Ms 30 m ·
0.25 mm · 0.25 lm) using the corresponding patterns (see
Table 4).
(19%, [Si(CH3)2Ph]+); 120 (9%, [Sn]+, Sn-pattern). Anal.
Calc. for C37H48O2Si3Sn: C, 61.07; H, 6.65. Found: C,
60.96; H, 6.48%.
3.4. Mass spectra and elemental analyses of the new vinyltin
compounds
3.4.6. (Z)-Ethyl-3-trineophylstannyl-3-phenylpropenoate
(22)
MS (m/z, rel. int.): 562 (100%, [MꢀNeoph]+, Sn-pat-
tern); 519 (75%, [SnNeoph3]+, Sn-pattern); 428 (3%,
[MꢀNeoph2]+, Sn-pattern); 385 (7%, [SnNeoph2]+, Sn-pat-
tern); 295 (20%, [MꢀNeoph3]+, Sn-pattern); 253 (14%,
[SnNeoph]+, Sn-pattern); 175 (28%, [MꢀSnNeoph3]+);
133 (9%, [Neoph]+); 120 (3%, [Sn]+, Sn-pattern); 105
(7%, [C8H9]+). Anal. Calc. for C41H50O2Sn: C, 71.00; H,
7.27. Found: C, 70.88; H, 7.10%.
3.4.1. (Z)-1-tris[(phenyldimethylsilyl)methyl)]stannyl-2-
phenylethene (5)
MS (m/z, rel. int.): 570 (3%, [Sn(CH2Si(CH3)2Ph)3]+, Sn-
pattern); 521 (100%, [Mꢀ(CH2Si(CH3)2Ph)]+, Sn-pattern);
453 (5%, Sn-pattern); 420 (2%, [Sn(CH2Si(CH3)2Ph)2]+,
Sn-pattern); 315 (21%, Sn-pattern); 270 (11%, [SnCH2-
Si(CH3)2Ph]+, Sn-pattern); 253 (17%, Sn-pattern); 223
(17%, [C8H7Sn]+, Sn-pattern); 197 (17%, Sn-pattern); 150
(6%, [CH2Si(CH3)2Ph]+); 136 (34%, [Si(CH3)2Ph]+); 120
(15%, [Sn]+, Sn-pattern); 77 (2%, [C6H5]+). Anal. Calc.
for C35H46Si3Sn: C, 62.77; H, 6.92. Found: C, 62.66; H,
6.78%.
3.4.7. Z-Ethyl-3-triptycyldimethylstannyl-3-
phenylpropenoate (24)
MS (m/z, rel. int.): 579 (6%, (6%, [M]+, Sn-pattern); 564
(20%, [Mꢀ(CH3)]+, Sn-pattern); 518 (12%, Sn-pattern);
403 (22%, [SnTrip(CH3)2]+, Sn-pattern); 388 (18%,
[SnTripCH3]+, Sn-pattern); 373 (10%, [SnTrip]+, Sn-pat-
tern); 325 (100%, [MꢀTrip]+, Sn-pattern); 280 (30%, Sn-
pattern); 253 (82%, [Trip]+); 150 (11%, [Sn(CH3)2]+, Sn-
pattern); 120 (2%, [Sn]+, Sn-pattern). Anal. Calc. for
C33H30O2Sn: C, 68.66; H, 5.24. Found: C, 68.30; H, 4.90%.
3.4.2. (Z)-3-triptycyldimethylstannyl-2-propen-1-ol (10)
MS (m/z, rel. int.): 445 (6%, [Mꢀ(CH3)]+, Sn-pattern);
403 (5%, [SnTrip(CH3)2]+, Sn-pattern); 373 (2%, [SnTrip]+,
Sn-pattern); 253 (100%, [Trip]+); 150 (41%, [Sn(CH3)2]+,
Sn-pattern); 57 (69%, [MꢀSnTrip(CH3)2]+). Anal. Calc.
for C25H24OSn: C, 65.39; H, 5.27. Found: C, 65.78; H,
5.38%.
3.4.8. (Z)-2-[(tris(phenyldimethylsilyl)methyl)stannyl]-
butenedioic acid dimethylester (26)
3.4.3. (Z)-4-[(tris(phenyldimethylsilyl)methyl)stannyl]-3-
buten-2-one (15)
MS (m/z, rel. int.): 561 (100%, [MꢀCH2Si(CH3)2Ph]+,
Sn-pattern); 452 (20%, Sn-pattern); 289 (12%, Sn-pattern);
261 (12%, [SnC6H7O4]+, Sn-pattern); 227 (31%, Sn-pat-
tern); 197 (13%, Sn-pattern); 150 (21%, [CH2Si(CH3)2Ph]+;
135 (43%, [Si(CH3)2Ph]+; 120 (20%, [Sn]+, Sn-pattern); 105
(8%, [Si(C6H5]+); 59 (4%, [C2H3O2]+). Anal. Calc. for
C33H46O4Si3Sn: C, 55.85; H, 6.53. Found: C, 55.70; H,
6.62%.
MS (m/z, rel. int.): 570 (4%, [Sn(CH2Si(CH3)2Ph)3]+,
Sn-pattern); 487 (100%, [Mꢀ(CH2Si(CH3)2Ph)]+, Sn-pat-
tern); 453 (6%, Sn-pattern); 357 (10%, Sn-pattern); 337
(4%, [Mꢀ(CH2Si(CH3)2Ph)2]+, Sn-pattern); 270 (9%,
[SnCH2Si(CH3)2Ph]+, Sn-pattern); 227 (13%, Sn-pattern);
203 (25%); 197 (28%, Sn-pattern); 135 (53%, [Si-
(CH3)2Ph]+); 120 (19%, [Sn]+, Sn-pattern). Anal. Calc.
for C31H44OSi3Sn: C, 58.58; H, 6.98. Found: C, 58.65; H,
6.80%.
Acknowledgements
This work was supported by grants from CONICET
(Ciudad de Buenos Aires, Argentina) and Universidad
3.4.4. 3-triptycyldimethylstannyl-3-buten-2-one (16)
MS (m/z, rel. int.): 457 (22%, [Mꢀ(CH3)]+, Sn-pattern);
403 (5%, [SnTrip(CH3)2]+, Sn-pattern); 373 (4%, [SnTrip]+,
Sn-pattern); 253 (75%, [Trip]+); 219 (100%, [MꢀTrip]+, Sn-
pattern); 189 (17%, [SnC4H5O]+, Sn-pattern); 135 (9%,
[SnCH3]+, Sn-pattern); 120 (2%, [Sn]+, Sn-pattern). Anal.
Calc. for C26H24OSn: C, 66.27; H, 5.13. Found: C, 66.65;
H, 5.34%.
´
Nacional del Sur (Bahıa Blanca, Argentina). A travel grant
to one of us (JCP) from the Alexander von Humboldt
Foundation (Germany), and a fellowship from DAAD
(Germany) to VID are also gratefully acknowledged.
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