Carbonyl allylations by 3-halopropenes or 2-propenyl mesylate with tin(IV) chloride and tetrabutylammonium iodide

Article abstract of DOI:10.1016/S0040-4039(03)00469-6

2-Propenyl tin species, prepared from 3-halopropenes or 2-propenyl mesylate with tin(IV) chloride and tetrabutylammonium iodide in dichloromethane, causes nucleophilic addition to aldehydes to produce the corresponding homoallylic alcohols.

Full text of DOI:10.1016/S0040-4039(03)00469-6

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 44 (2003) 2845–2847
Carbonyl allylations by 3-halopropenes or 2-propenyl mesylate
with tin(IV) chloride and tetrabutylammonium iodide
Yoshiro Masuyama,* Takanori Suga, Akiko Watabe and Yasuhiko Kurusu
Department of Chemistry, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan
Received 17 January 2003; revised 10 February 2003; accepted 14 February 2003
Abstract—2-Propenyl tin species, prepared from 3-halopropenes or 2-propenyl mesylate with tin(IV) chloride and tetra-
butylammonium iodide in dichloromethane, causes nucleophilic addition to aldehydes to produce the corresponding homoallylic
alcohols. © 2003 Elsevier Science Ltd. All rights reserved.
Allylic tin is one of the most convenient allylating
agents in carbonyl allylations.1,2 Allylic trihalotins,
derived from starting allylic compounds such as allylic
halides,3 alcohols4 and esters4b,5 with tin(II) halides in
situ, namely under Barbier conditions, especially have
the advantage of the availability and tractability of
both the starting allylic compounds and tin(II) halides.
The reactivity in the carbonyl allylation by (E)-but-2-
en-1-ol with tin(II) chloride is dependent upon the
solubility of tin(II) chloride, while the regioselectivity is
dependent upon the dielectric constants of the sol-
vents;4,6 polar solvents such as 1,3-dimethylimidazo-
lidin-2-one, DMF and THF–H2O let the allylation
proceed smoothly for obtaining high yields with g-anti
selectivity, while nonpolar solvents such as diethyl ether
and dichloromethane lead to unusual a-regioselection7
without practical yields because of the insolubility of
tin(II) chloride. The carbonyl allylation in the nonpolar
solvents needs special conditions such as ultrasonic6 or
biphasic3i systems to dissolve tin(II) chloride. A new
synthetic methodology will be required for preparing
allylic tin species in the nonpolar and low-boiling sol-
vents under general Barbier conditions.8 Since tin(IV)
chloride is soluble in nonpolar solvents such as
dichloromethane and benzene, in contrast to tin(II)
chloride, finding a reducing method of tin(IV) chloride
to tin(II) species will make it possible to prepare allylic
tins from the usual starting allylic compounds in non-
polar solvents. Here, we report on (1) a novel prepara-
tion of 2-propenyltin species from 3-halopropenes or
2-propenyl mesylate with tin(IV) chloride and tetra-
butylammonium iodide (TBAI)9 in dichloromethane
and carbonyl allylations by the 2-propenyltin species,
and (2) an application of the carbonyl allylation to
g-syn selection, rather than the a-regioselection in
dichloromethane and anti-diastereoselection in polar
solvents in the previous carbonyl allylation with tin(II)
chloride.3–5
The allylation of benzaldehyde by 2-propenyl bromide
(1a), chloride (1b), or mesylate (1c) with tin(IV) chlo-
ride and TBAI was investigated under various condi-
tions (Scheme 1). The results are summarized in Table
1 (entries 1–5 and 13). An optimum experiment is as
follows (entry 13): To the solution of 1c (2 mmol),
benzaldehyde (1 mmol) and TBAI (6 mmol) in
dichloromethane (3 ml) was added
a one-molar
dichloromethane solution of tin(IV) chloride (2 ml) on
an ice-bath for 10–15 min, and then the solution was
stirred at room temperature for 44 h. After usual
work-up and purification by column chromatography,
Keywords: nucleophilic additions; allylations; allylic tins; homoallylic
alcohols; tin(IV) chloride.
* Corresponding author. Fax: +81-3-3238-3361; e-mail: y-masuya@
sophia.ac.jp
Scheme 1.
0040-4039/03/$ - see front matter © 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0040-4039(03)00469-6

2846
Y. Masuyama et al. / Tetrahedron Letters 44 (2003) 2845–2847
Table 1. Carbonyl allylations by 1 with SnCl4 and TBAIa
1-phenyl-3-buten-1-ol (2, R=Ph) was obtained in 71%
yield. In the allylation by 1b, 3 mmol of 1b, 3 mmol
of tin(IV) chloride and 9 mmol of TBAI each to 1
mmol of benzaldehyde were needed for obtaining
almost the same yield as that obtained by 1c (entry
5). Tin(IV) chloride and TBAI each can be saved by
the use of 1c that itself is also saved. Thus, mesylate
1c is superior to halides 1a and 1b in the carbonyl
allylations. The allylations may require more than
three equimolar amounts of TBAI to tin(IV) chloride.
No pinacol coupling product was obtained under
these conditions, in contrast to the TiCl4–TBAI
reducing system for pinacol coupling.9 No allylation
took place at temperatures below −20°C. Carbonyl
allylations using 1b and 1c were carried out with vari-
ous aldehydes under the optimum conditions of benz-
aldehyde (entries 5 and 13, respectively). Benzalde-
hydes bearing an electron-donating or electron-with-
drawing group, a,b-unsaturated aldehydes, and
aliphatic aldehydes can be employed for the carbonyl
allylations (Table 1).10
Entry
Substrate
R
Time (h)
2, Yield
(%)b
1
1a
1a
1a
1b
1b
1b
1b
1b
1b
1b
1b
1b
1c
1c
1c
1c
1c
1c
1c
1d
1d
Ph
Ph
Ph
Ph
48
48
48
24
24
48
24
48
48
48
48
48
24
48
24
24
48
48
48
48
48
41
45
8
2c
3d
4
29
72
52
76
23
37
31
62
45
71
68
65
88
50
55
61
49
34
5e
Ph
6e
4-MeC6H4
4-ClC6H4
PhCHꢀCH
PhCH2CH2
H2CꢀCH(CH2)8
C6H13
7e
8e
9e
10e
11e
12e
13
14
15
16
17
18
19
20
21
c-C6H11
Ph
4-MeC6H4
4-ClC6H4
4-MeOOCC6H4
PhCH2CH2
C6H13
c-C6H11
Ph
C6H13
Some selectivity in carbonyl allylation was demon-
strated with SnCl4–TBAI: (1) Chemoselective allyla-
tions of aldehydes using 1b and 1c can be realized in
the presence of ketones; the allylation of benzalde-
hyde in the presence of acetophenone and the allyla-
tion of heptanal in the presence of 2-heptanone
(Scheme 2).10 No allylation of ketones occurred under
a After adding a one-molar dichloromethane solution of tin(IV) chlo-
ride (2 ml) to the solution of 1a, 1b, 1c or 1d (2 mmol), aldehydes
(1 mmol) and TBAI (6 mmol) in dichloromethane (3 ml) on an
ice-bath for 10–15 min, the reaction was carried out at room
temperature.
b Isolated yields.
c The reaction was carried out at 40°C.
these conditions. (2) 2-Phenylpropanal bearing
a
d The reaction was carried out at 0°C.
stereocenter at the 2-position underwent Felkin-Anh-
type allylation by 1c to produce 2(anti)-phenyl-5-
hexen-3-ol as a major product (Scheme 3).10 (3) The
carbonyl allylation by 1-chloro-2-butene (3)† with
SnCl4-TBAI under the same conditions as those of 1b
g-regioselectively occurred with syn-diastereoselection
(Scheme 4).10,11
e Aldehydes (1 mmol), 1b (3 mmol), TBAI (9 mmol), and a one-molar
dichloromethane solution of SnCl4 (3 ml) were used.
This carbonyl allylation is outlined in Scheme 5, by
reference to the pinacol coupling with TiCl4-TBAI
reagent.9 Iodide ion probably serves as a reducing
agent for preparing trichlorostannate(II) ion (−SnCl3)
from SnCl4 via the formation of pentacoordinate
stannate(IV) ion (−SnCl4I) followed by the reductive
elimination of iodine monochloride (I-Cl). The
trichlorostannate(II) ion may cause nucleophilic sub-
Scheme 2.
stitution to allyl substrates
1 to prepare allyl-
trichlorotin that functions as an allylic nucleophile for
carbonyl allylation. I-Cl may react with two equimo-
lar amounts of TBAI to produce TBACl and tetra-
butylammonium triiodide (TBAI3).12 Since excess
tin(IV) species are present in the reaction system, the
carbonyl allylation with 3 probably proceeds via an
acyclic antiperiplanar transition state between 2-
butenyltrichlorotin and aldehyde coordinating another
tin(IV) to exhibit g-syn-selectivity.1 In contrast to
TiCl4–TBAI, SnCl4–TBAI is a useful reagent for Bar-
bier-type carbonyl allylation because it lacks the abil-
ity to reduce aldehydes.
Acknowledgements
This work was supported by Grant-in-Aid for Scien-
tific Research (C) from Japan Society for the Promo-
tion of Science (JSPS).
† 1-Chloro-2-butene was purchased from Aldrich Chemical Co., Inc.

Y. Masuyama et al. / Tetrahedron Letters 44 (2003) 2845–2847
2847
Scheme 3.
Scheme 4.
A.; Kurusu, Y. Chem. Commun. 1998, 315; (i) Ito, A.;
Kishida, M.; Kurusu, Y.; Masuyama, Y. J. Org. Chem.
2000, 65, 494.
4. (a) Masuyama, Y. J. Synth. Org. Chem., Jpn. 1992, 50,
202; (b) Masuyama, Y. In Advances in Metal-Organic
Chemistry; Liebeskind, L. S., Ed.; JAI Press: Greenwich,
CT, 1994; Vol. 3, p. 255; (c) Masuyama, Y.; Ito, T.;
Tachi, K.; Ito, A.; Kurusu, Y. Chem. Commun. 1999,
1261.
5. Matsubara, S.; Wakamatsu, K.; Morizawa, Y.; Tsub-
oniwa, N.; Oshima, K.; Nozaki, H. Bull. Chem. Soc. Jpn.
1985, 58, 1196.
6. (a) Masuyama, Y.; Hayakawa, A.; Kurusu, Y. J. Chem.
Soc., Chem. Commun. 1992, 1102; (b) Masuyama, Y.;
Hayakawa, A.; Kishida, M.; Kurusu, Y. Inorg. Chim.
Acta 1994, 220, 155.
7. For a-regioselective carbonyl allylations, see: (a)
Yamamoto, Y.; Maruyama, K. J. Org. Chem. 1983, 48,
1564; (b) Kanagawa, A.; Nishiyama, Y.; Ishii, Y. J. Org.
Chem. 1992, 57, 6988; (c) Yanagisawa, A.; Habaue, S.;
Yasue, K.; Yamamoto, H. J. Am. Chem. Soc. 1994, 116,
6130.
8. For in situ preparation of allylic tins in nonpolar solvents
except for the reaction of allylic compounds such as
allylic halides, alcohols or esters with tin(II) halides, see:
(a) Ref. 2a; (b) Masuyama, Y.; Saeki, K.; Horiguchi, S.;
Kurusu, Y. Synlett 2001, 1802.
Scheme 5. A plausible mechanism.
References
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10. The structure of all products in the carbonyl allylation
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NMR, and 13C NMR spectra with those of an authentic
sample prepared from tetrabutylammonium iodide and
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