Transmetallations between aryltrialkyltins and borane: Synthesis of arylboronic acids and organotin hydrides

Article abstract of DOI:10.1016/S0022-328X(00)00536-2

Aryltrialkyltin compounds react with borane in THF to give mixtures of trialkyltin hydrides and arylboranes, which on hydrolysis give arylboronic acid in high yields. The arylboronic acids are easily separated and obtained free of organotins.

Full text of DOI:10.1016/S0022-328X(00)00536-2

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 613 (2000) 236–238
Transmetallations between aryltrialkyltins and borane: synthesis of
arylboronic acids and organotin hydrides
1
1
M.B. Faraoni, L.C. Koll , S.D. Mandolesi, A.E. Z u´ n˜ iga, J.C. Podest a´ *
Instituto de In6estigaciones en Qu ´ı mica Org a´ nica, Departamento de Qu ´ı mica e Ingenier ´ı a Qu ´ı mica, Uni6ersidad Nacional del Sur,
A6enida Alem 1253, 8000 Bah ´ı a Blanca, Argentina
Received 10 April 2000; received in revised form 7 July 2000
Abstract
Aryltrialkyltin compounds react with borane in THF to give mixtures of trialkyltin hydrides and arylboranes, which on
hydrolysis give arylboronic acid in high yields. The arylboronic acids are easily separated and obtained free of organotins. © 2000
Elsevier Science B.V. All rights reserved.
Keywords: Transmetallations; Aryltrialkyltins; Borane; Organotin hydrides; Arylboronic acids
1
. Introduction
organometallic compound ratios (four- to tenfold ex-
cess of borane).
Taking into account that the tin-sp carbon bond
3
Arylboronic acids are valuable reagents for organic
synthesis. Thus, they have lately been employed in the
synthesis of achiral and chiral alcohols [1], of diaryl
ethers [2], and are also currently used for palladium-
catalyzed cross-coupling reactions with organic halides
or triflates leading to the formation of carbon-carbon
bonds (Suzuki reaction) [3]. The boronic acids are
generally prepared via the reaction of boron halides (or
esters of boric acid) with organometallic compounds
does not react with borane in THF [8], we considered
of interest to study the reactions between aryltrialkyltin
compounds and borane in THF as a potentially useful
route to arylboronic acids and organotin hydrides.
2
. Results and discussion
Preliminary experiments were first carried out, using
[
5
4]. The yields, however, are usually fairly modest (ca.
0%). A more recent procedure for the synthesis of
phenyltri-n-butyltin, under a variety of reaction condi-
tions to determine whether or not transmetallation
occurred and, if it did, the optimum conditions.
The organotin compound was dissolved in dry THF
and treated with a solution of borane in the same
solvent. After completion of the reaction, water was
added to transform the arylborane into the correspond-
ing arylboronic acid and to eliminate any excess of
borane. We found that the hydrolysis of the reaction
mixtures led to phenylboronic acid and tri-n-butyltin
hydride in good to excellent yields according to the
reaction conditions, as shown in Scheme 1 (R=n-Bu-
tyl, Ar=Phenyl).
arylboronic esters in high yields (ca. 80%) is the Pd(0)-
catalyzed cross coupling reaction of the pinacol ester of
diboron with haloarenes [5]. The exchange reactions
between borane in THF and arylmetallic derivatives of
Li, Na, K, Ca [6a], Hg [6b], Tl [6c], Pb [6d], Sn [6d,e],
and Mg [7] also lead to arylboronic acids. With most of
the organometallic compounds studied the yields were
low (9% to a maximum of ca. 60%) due, in some cases,
to the formation of other organoboron derivatives such
as borinic acids and triarylboron. It should be noted
that the best results were obtained using high borane/
These studies included variations of the borane/
phenyltri-n-butyltin ratios in the range of 1–8 and of
the times of heating under reflux in the range of 1–4 h.
The optimum conditions found were a ratio borane/
*
Corresponding author. Tel.: +54-91-26420/280345; fax: +54-
2
91-459-5187.
1
E-mail address: jpodesta@criba.edu.ar (J.C. Podest a´ ).
1
Member of CONICET (Argentina).
0
022-328X/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00536-2

M.B. Faraoni et al. / Journal of Organometallic Chemistry 613 (2000) 236–238
237
the arylboronic acid with hexane–diethyl ether (1:1).
The arylboronic acids were then recrystallized from
water; their melting points were coincident with those
reported in the literature and the mixed melting points
Scheme 1. Exchange reactions between aryltrialkyltin compounds and
borane in THF.
1
with authentic samples showed no depression. H- and
13
organotin of 1.05 and 1 h heating. Under these reaction
conditions tri-n-butyltin hydride was obtained in 85%
yield and phenylboronic acid in 96% yield. It should be
noted that, although longer periods of heating do not
affect the yield of tin hydride they do diminish the
yields of phenylboronic acid, probably due to the ther-
mal decomposition of the intermediate phenylborane.
We then studied the reaction of a series of aryltri-n-
butyltins and phenyltrialkyltins with borane in THF,
under the same reaction conditions, and found that
these reactions also lead to mixtures of trialkyltin hy-
drides and arylboronic acids, in most cases with excel-
lent yields. The results obtained are summarized in
Table 1.
C-NMR spectra also showed that the boronic acids
were completely free of organotin residues. It should be
noted that the organotin hydrides could be either em-
ployed for performing their typical reactions or recon-
verted into the starting trialkyltin chloride through
their reaction with carbon tetrachloride.
In summary, we have developed a method for a
quick and low cost synthesis on a preparative scale of
arylboronic acids and trialkyltin hydrides in high yields.
The trialkyltin moiety, used as a ‘carrier’ of the aryl
groups, is recovered in high yield after the reactions
and could be reused. The method also has the advan-
tage that the arylboronic acids are obtained pure and
uncontaminated by organotin residues and by other
organic and inorganic boron derivatives as well as free
of halides. The only limitation of this method is that it
is restricted to those aryl derivatives with substituents
that do not react with Grignard reagents.
As shown in Table 1, only in the case of 1-naphthyl
derivatives (entries 6 and 7) was the formation of
product of reduction (naphthalene) observed. In Table
1
it can also be seen that the size of the alkyl ligands
(
entries 8 and 9) affect the yields of products to some
3
. Experimental
extent. Thus, in the case of the octyl ligand (entry 8)
whereas the yield of the triorganotin hydride is the
same as that obtained when the alkyl ligand was butyl
The starting tri-n-butylphenyl- and tri-n-butyl-1-
naphthyltin compounds were obtained from the reac-
tion between tri-n-butyltin chloride and the
corresponding arylmagnesium derivatives [9]. Following
the same procedure, o-anisyltri-n-butyltin, p-anisyltri-
n-butyltin, o-tolyltri-n-butyltin, p-tolyltri-n-butyltin,
phenyltri-n-octyltin, and phenyltri-n-dodecyltin were
also obtained, their H- and C-NMR characteristics
are shown below.
All the exchange reactions were carried out following
the same technique. One reaction is described in detail
in order to illustrate the method used.
(
entry 1), the yield of phenylboronic acid is lower. In
the case of the dodecyl ligand (entry 9), the yields of
both tin hydride and phenylboronic acid are noticeable
lower compared with the yields obtained with the butyl
ligand (entry 1).
The mixtures of arylboronic acids and organotin
hydrides thus obtained can then be easy and completely
separated by column chromatography on silica gel 60,
the organotin hydrides being eluted with hexane and
1
13
Table 1
To a stirred solution of phenyltri-n-butyltin (1 g, 2.7
mmol) in dry THF (10 ml), was added a solution of
borane in THF (0.0028 mmol, 1.8 ml of a 1.58 M
solution). The preparation was carried out under an
atmosphere of nitrogen. The mixture was left at room
temperature for 1 h and then refluxed during 1 h. After
cooling, diethyl ether (10 ml) and water (0.1 ml) were
added, the solution was dried with magnesium sulphate,
and the solvent was removed under vacuum. The crude
product was purified by column chromatography (silica
gel 60), tri-n-butyltin hydride (0.67 g, 0.0023 mmol,
a
Reactions of aryltrialkyltin compounds with borane in THF
Entry Ar
R
Ar–B(OH)
R SnH
(%)
2
3
b
b
(
%)
1
2
3
4
5
6
7
8
9
Phenyl
n-Butyl
n-Butyl
n-Butyl
n-Butyl
n-Butyl
96
83
85
85
88
48
68
80
85
86
84
90
91
o-Tolyl
p-Tolyl
o-Anisyl
p-Anisyl
c
c
1-Naphthyl n-Butyl
1-Nahphtyl n-Butyl
72
95
d
d
−
1
−1
Phenyl
Phenyl
n-Octyl
n-Dodecyl 71
86
78
85%), wSn–H 1811 cm
(Ref. [10], p. 68, 1811 cm ),
being eluted with hexane and phenylboronic acid (0.317
g, 0.0026 mmol, 96%) with hexane–diethyl ether (1:1).
After one recrystallization from water, the phenyl-
boronic acid gave m.p. 214–216°C (Ref. [10] 216°C).
The mixed m.p. with an authentic sample [6d] showed
no depression.
a
b
c
One hour heating except when otherwise stated.
Yields of pure, isolated products (average of five experiments).
Also starting organotin and 26% of reduction product (naphtha-
lene).
d
Three hours heating; 32% of reduction.

2
38
M.B. Faraoni et al. / Journal of Organometallic Chemistry 613 (2000) 236–238
Following the same procedure we obtained the
3.1.6. Phenyltri-n-dodecyltin
lH: 0.80 (t, 6H, J=6.6); 0.96 (t, 9H, J=7.7); 1.05–
1.71 (m, 60H); 7.20 (m, 2H); 7.36 (m, 3H). l : 9.85
(338.9); 13.9; 22.60; 26.75 (20.5); 29.12; 29.28; 29.54;
29.56; 29.58; 29.61; 31.86; 34.30 (53.6); 127.79; 127.82
(41.1); 136.39 (31.2); 142.03 (394.9).
−
1
known [4,10,11] tri-n-octyl- (wSn–H 1815 cm ) and
−
1
tri-n-dodecyltin hydrides (wSn–H 1806 cm ), as well as
p-tolylboronic acid (m.p. 242–243°C), o-tolylboronic
acid (m.p. 168°C), p-anisylboronic acid (m.p. 202–
C
2
04°C), o-anisylboronic acid (m.p. 165°C), and 1-naph-
thylboronic acid (m.p. 182–183°C).
1
13
Acknowledgements
3
.1. H- and C-NMR of the new
2
aryltrialkylcompounds
This work was supported by CONICET (Capital
Federal, Argentina), CIC (Provincia de Buenos Aires,
Argentina), and Universidad Nacional del Sur (Bah ´ı a
Blanca, Argentina). The generous help of Prof. M.
Gonz a´ lez Sierra (IQUIOS, Rosario, Argentina) and
Prof. T.N. Mitchell (Dortmund University, Dortmund,
Germany) in obtaining the NMR spectra is gratefully
acknowledged.
3
.1.1. o-Anisyltri-n-butyltin
lH: 0.80 (t, 9H, J=7.5); 0.95 (t, 6H, J=7.4) 1.24 (m,
H); 1.44 (m, 6H); 3.69 (s, 3H); 6.73 (d, 1H, J=8.7),
.87 (m, 1H); 7.22 (m, 1H); 7.28 (d, 1H, J=6.7). lC:
0.12 (332.4); 14.11; 27.75 (30.1); 29.55 (21.4); 55.41;
09.28 (21.4); 121.25 (38.9); 130.03; 130.71 (367.3);
37.34 (31.2); 164.15.
6
6
1
1
1
3.1.2. p-Anisyltri-n-butyltin
References
lH: 0.88 (t, 9H, J=7.4); 1.02 (t, 6H, J=8.2); 1.32
m, 6H); 1.52 (m, 6H); 3.78 (s, 3H); 6.90 (d, 2H,
[
[
1] (a) M. Sakai, M. Ueda, N. Miyaura, Angew. Chem. 110 (1998)
475; Angew. Chem. Int. Ed. Engl. 37 (1998) 3279.
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T.R. West, Tetrahedron Lett. 39 (1998) 2937.
(
3
J=8.1); 7.37 (d, 2H, J=8.5). l : 9.09 (325.06); 13.58;
C
2
(
6.89 (30.8); 28.62 (19.8); 54.77; 113.72 (21.7); 131.84
364.5); 137.13 (35.5); 159.59.
[
3] A. Suzuki, Chapter 2, in: F. Diederich, P.J. Stang (Eds.), Metal
Catalyzed Cross-Coupling Reactions, Weinheim, Wiley-VCH,
3
.1.3. o-Tolyltri-n-butyltin
lH: 0.97 (t, 6H, J=7.3); 1.16 (t, 9H, J=8.3); 1.42
1
998.
[4] A.N. Nesmeyanov, R.A. Sokolik, Methods of Elementoorganic
Chemistry, vol. 1 (B, Al, Ga, In, Th), North Holland, Amster-
dam, 1967.
(
7
2
m, 6H); 1.62 (m, 6H); 2.48 (s, 3H); 7.17–7.33 (m, 3H);
.48 (m, 1H). l : 10.43 (336.4); 14.12; 25.45 (23.2);
C
[
5] T Ishiyama, M. Murata, N. Miyaura, J. Org. Chem. 60 (1995)
508.
7.87 (60.3); 29.62 (20.4); 125.30 (42.6); 128.71; 129.28
34.8); 136.94 (31.0); 142.40 (359.6); 145.04.
7
(
[
6] (a) F.G. Thorpe, G.M. Pickles, J.C. Podest a´ , J. Organomet.
Chem. 128 (1977) 305. (b) S.W.F. Breuer, F.G. Thorpe, J.C.
Podest a´ , Tetrahedron Lett. 42 (1974) 3719. (c) G.M. Pickles, T.
Spencer, F.G. Thorpe, A.D. Ayala, J.C. Podest a´ , J. Chem. Soc.
Perkin Trans. I (1982) 2949. (d) F.G. Thorpe, S.W. Breuer, G.M.
Pickles, T. Spencer, J.C. Podest a´ , J. Organomet. Chem. 145
(1978) C26. (e) G.M. Pickles, T. Spencer, F.G. Thorpe, A.B.
Chopa, J.C. Podest a´ , J. Organomet. Chem. 260 (1984) 7.
3
.1.4. p-Tolyltri-n-butyltin
lH: 0.88 (t, 6H, J=7.2); 1.03 (t, 9H, J=7.3); 1.33
m, 6H); 1.52 (m, 6H); 4.10 (s, 3H); 7.14 (d, 2H,
(
J=7.4); 7.35 (d, 2H, J=7.5). l : 9.40 (324.3); 13.55;
C
2
(
1.27; 27.27 (57.5); 28.98 (20.4); 128.75 (40.4); 136.34
32.6); 137.48 (379.7); 137.73.
[
[
[
7] G.W. Kabalka, U. Sastry, K.A.R. Sastry, J. Organomet. Chem.
2
59 (1983) 268.
8] A.B. Chopa, L.C. Koll, J.C. Podest a´ , F.G. Thorpe, Synthesis
(1983) 722.
9] H. Schumann, I. Schumann, Gmelin Handbuch der Anorganis-
chen Chemie, Band 29, Zinn-Organische Verbindungen, Teil 2,
Springer Verlag, New York, 1975.
3
.1.5. Phenyltri-n-octyltin
lH: 0.93 (t, 6H, J=6.9); 1.09 (t, 9H, J=7.7); 1.20–
1
(
3
(
51 (m, 36H); 7.36 (m, 2H); 7.51 (m, 3H). l : 9.80
C
338.6); 14.00; 22.59; 26.76 (20.8); 29.08; 29.20; 33.56;
4.32 (53.2); 127.81 (39.0); 127.82 (39.0); 128.63; 141.99
360.5).
[
[
10] M.F. Lappert, Chem. Rev. 56 (1956) 959.
11] W.P. Neumann, Chapter 3, in: The Organic Chemistry of Tin,
John Wiley & Sons, London, 1970 and references cited therein.
.
2
In CDCl ; chemical shits, l, in ppm with respect to TMS, in 1H
3
1
3
3
n
spectra, and to CDCl3 in C spectra; J (H,H) and J (Sn,C)
coupling constants in Hz (in brackets).