J. Am. Chem. Soc. 1996, 118, 4723-4724
4723
Catalytic Asymmetric Allylation of Aldehydes Using
a Chiral Silver(I) Complex
Table 1. Allylation Reaction of Benzaldehyde with Allyltributyltin
in the Presence of Various Chiral Phosphine-Silver(I) Complexes
a
Akira Yanagisawa, Hiroshi Nakashima, Atsushi Ishiba, and
Hisashi Yamamoto*
School of Engineering, Nagoya UniVersity
Chikusa, Nagoya 464-01, Japan
ReceiVed January 31, 1996
c
Enantioselective allylation of carbonyl compounds is a
challenging problem in organic synthesis. Although numerous
important works on the reaction using a stoichiometric amount
entry
complex
yield, %b
% ee (config)
1
2
3
4
5
6
7
(S)-BINAP‚AgOCOCF
3
47
1
26
88
97
4
40 (S)
26 (S)
53 (S)
96 (S)
2 (R)
48 (R)
3 (R)
(S)-BINAP‚AgClO
(S)-BINAP‚AgNO
4
1
of chiral Lewis acids have been reported, there are only a few
3
methods available for a catalytic process including chiral
(S)-BINAP‚AgOTf
2
(
acyloxy)borane (CAB) complex/allylic silanes or allylic stan-
(R,R)-CHIRAPHOS‚AgOTf
(S,S)-Me-DUPHOS‚AgOTf
(S,S)-Et-DUPHOS‚AgOTf
3
nanes and binaphthol-derived chiral titanium complexes/allylic
stannanes.4 Described herein is a new catalytic enantioselective
13
allylation reaction of aldehydes with allyltributyltin using
a
Unless otherwise specified, the reaction was carried out using chiral
BINAP‚silver(I) complex as a catalyst (eq 1).
phosphine‚AgX (0.05 equiv), allyltributyltin (1 equiv), and benzalde-
hyde (1 equiv) in THF at -20 °C for 8 h. Isolated yield. c Determined
by HPLC analysis (Chiralcel OD-H, Daicel Chemical Industries, Ltd.).
b
aged us to use chiral phosphine-silver(I) complex as a catalyst
for asymmetric allylation of carbonyl compounds with allyl-
stannanes.
We have recently shown that highly chemoselective allylation
of carbonyl compounds occurs using tetraallyltin in acidic
aqueous media.5 Our continuing interest in selective allylation
has led us to undertake an investigation of allylation of
aldehydes with allyltributyltin catalyzed by various metal
compounds. Among the metal catalysts examined, silver(I)
compound was found to be one of the most unique. For
example, treatment of benzaldehyde with allyltributyltin in the
presence of 5 mol % of silver(I) trifluoroacetate in a 1:1 mixture
of THF and H2O at 20 °C for 4 h produced the homoallylic
alcohol in moderate yield.6 Noteworthy was the fact that
addition of 10 mol % of triphenylphosphine improved the
chemical yield significantly up to >90%. This result encour-
The BINAP‚silver(I) catalyst was prepared by stirring an
equimolar mixture of (S)-BINAP and silver(I) triflate in THF
at room temperature for 10 min. Treatment of benzaldehyde
with allyltributyltin (1 equiv) in THF under the influence of
this catalyst (5 mol %) at -20 °C for 8 h gave the (S)-enriched
homoallylic alcohol in 88% yield with 96% ee (Table 1, entry
4). Using various chiral phosphine-silver(I) catalysts, we
studied the enantioselectivity of this process; enantio excesses
and yields of the products obtained by the reaction with 5 mol
% of other chiral phosphine-silver(I) complexes in THF at -20
°C are shown in Table 1. The reaction catalyzed by the
BINAP‚silver(I) triflate complex at -20 °C afforded the highest
(
1) Allylboranes: (a) Brown, H. C.; Jadhav, P. K. J. Am. Chem. Soc.
7
yield and ee.
1
1
983, 105, 2092. (b) Short, R. P.; Masamune, S. J. Am. Chem. Soc. 1989,
11, 1892. (c) Racherla, U. S.; Brown, H. C. J. Org. Chem. 1991, 56, 401.
Table 2 summarizes the results obtained for the reaction of
a variety of aldehydes with 1 equiv of allyltributyltin at -20
Allylboronates: (d) Herold, T.; Hoffmann, R. W. Angew. Chem., Int. Ed.
Engl. 1978, 17, 768. (e) Hoffmann, R. W.; Herold, T. Chem. Ber. 1981,
°
C in THF. The characteristic features of the results are as
1
1
3
14, 375. (f) Roush, W. R.; Walts, A. E.; Hoong, L. K. J. Am. Chem. Soc.
985, 107, 8186. (g) Roush, W. R.; Banfi, L. J. Am. Chem. Soc. 1988, 110,
979. (h) Roush, W. R.; Hoong, L. K.; Palmer, M. A. J.; Park, J. C. J. Org.
follows: (1) all reactions resulted in high yields and remarkable
enantioselectivities not only with aromatic aldehydes but also
with R,â-unsaturated aldehydes (entries 2 and 5), with the
exception of aliphatic aldehyde, which gave relatively low
chemical yield and enantioselectivity (entry 9); (2) in the
reaction with R,â-unsaturated aldehydes, the 1,2-addition reac-
tion proceeded exclusively (entries 2 and 5); (3) the methyl
group at the ortho-position of benzaldehyde had no effect on
the enantioselectivity (compare entries 1 and 6); (4) an electron-
withdrawing substituent at the para-position of benzaldehyde
increased the rate of the allylation (compare entries 1, 7, and
Chem. 1990, 55, 4109. See also: (i) Reetz, M. T.; Zierke, T. Chem. Ind.
988, 663. Allylboradiazolidines: (j) Corey, E. J.; Yu, C.-M.; Kim, S. S.
1
J. Am. Chem. Soc. 1989, 111, 5495. Allyltitanates: (k) Riediker, M.;
Duthaler, R. O. Angew. Chem., Int. Ed. Engl. 1989, 28, 494. (l) Schmidt,
B.; Seebach, D. Angew. Chem., Int. Ed. Engl. 1991, 30, 99. (m) Hafner,
A.; Duthaler, R. O.; Marti, R.; Rihs, G.; Rothe-Streit, P.; Schwarzenbach,
F. J. Am. Chem. Soc. 1992, 114, 2321. Allylaluminum derivatives: (n)
Minowa, N.; Mukaiyama, T. Bull. Chem. Soc. Jpn. 1987, 60, 3697.
Allylstannanes: (o) Otera, J.; Kawasaki, Y.; Mizuno, H.; Shimizu, Y. Chem.
Lett. 1983, 1529. (p) Otera, J.; Yoshinaga, Y.; Yamaji, T.; Yoshioka, T.;
Kawasaki, Y. Organometallics 1985, 4, 1213. (q) Boldrini, G. P.; Tagliavini,
E.; Trombini, C.; Umani-Ronchi, A. J. Chem. Soc., Chem. Commun. 1986,
6
85. (r) Boldrini, G. P.; Lodi, L.; Tagliavini, E.; Tarasco, C.; Trombini, C.;
8
).
Umani-Ronchi, A. J. Org. Chem. 1987, 52, 5447. (s) Boga, C.; Savoia, D.;
Tagliavini, E.; Trombini, C.; Umani-Ronchi, A. J. Organomet. Chem. 1988,
Additions of methallylstannanes to aldehydes were also
3
53, 177.
achieved highly enantioselectively using this method.8 For
(2) (a) Furuta, K.; Mouri, M.; Yamamoto, H. Synlett 1991, 561. (b)
Ishihara, K.; Mouri, M.; Gao, Q.; Maruyama, T.; Furuta, K.; Yamamoto,
H. J. Am. Chem. Soc. 1993, 115, 11490.
(6) Results of the catalytic reaction using various metal compounds (range
of yields, metal catalysts): 54-44% yields, AgOCOCF3, AgOTf, AgNO3,
PdCl2, and PtCl2; 22-11% yields, SnCl4, VCl3, ReCl5, BiCl3, and InCl3;
4-0% yields, Sc(OTf)3, FeCl3, BF3‚OEt2, TiCl4, AlCl3, and MgCl2.
(7) Results of the reaction carried out at various temperatures (temper-
ature, yield, enantioselectivity): 20 °C, 16% yield, 79% ee; 0 °C, 16%
yield, 86% ee; -20 °C, 88% yield, 96% ee; -45 °C, 54% yield, 94% ee;
-78 °C, <1% yield. The catalyst was deactivated for prolonged periods
above 0 °C.
(
3) Marshall, J. A.; Tang, Y. Synlett 1992, 653.
(
4) (a) Aoki, S.; Mikami, K.; Terada, M.; Nakai, T. Tetrahedron 1993,
4
9, 1783. (b) Costa, A. L.; Piazza, M. G.; Tagliavini, E.; Trombini, C.;
Umani-Ronchi, A. J. Am. Chem. Soc. 1993, 115, 7001. (c) Keck, G. E.;
Tarbet, K. H.; Geraci, L. S. J. Am. Chem. Soc. 1993, 115, 8467. (d) Keck,
G. E.; Geraci, L. S. Tetrahedron Lett. 1993, 34, 7827. (e) Keck, G. E.;
Krishnamurthy, D.; Grier, M. C. J. Org. Chem. 1993, 58, 6543. See also:
(
f) Keck, G. E.; Krishnamurthy, D.; Chen, X. Tetrahedron Lett. 1994, 35,
323.
5) Yanagisawa, A.; Inoue, H.; Morodome, M.; Yamamoto, H. J. Am.
Chem. Soc. 1993, 115, 10356.
(8) Enantioselective methallyl additions to aldehydes have been achieved
9
1j
8
using methallylborane, methallylboradiazolidines, CAB catalyst/meth-
2
(
allylsilane, and binaphthol-derived chiral titanium catalysts/methallyl-
stannane.4e
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