Cr(salen)-catalyzed asymmetric addition of allylstannane to aldehydes

Article abstract of DOI:10.1246/cl.2005.786

Cr(salen) complex 3 was found to be an efficient catalyst for asymmetric addition of allyltributylstannane to non-branched aliphatic aldehydes, giving the corresponding homoallylic alcohols in a highly enantioselective manner. For example, its addition to

Full text of DOI:10.1246/cl.2005.786

786
Chemistry Letters Vol.34, No.6 (2005)
Cr(salen)-catalyzed Asymmetric Addition of Allylstannane to Aldehydes
Yuya Shimada and Tsutomu Katsukiꢀ
Department of Chemistry, Faculty of Science, Graduate School, Kyushu University 33,
Hakozaki, Higashi-ku, Fukuoka 812-8581
(Received March 7, 2005; CL-050301)
Cr(salen) complex 3 was found to be an efficient catalyst for
substituent plays an important role in the asymmetric induction
and the expected ligand acceleration16 (Entry 5).
asymmetric addition of allyltributylstannane to non-branched
aliphatic aldehydes, giving the corresponding homoallylic alco-
hols in a highly enantioselective manner. For example, its addi-
tion to 3-phenylpropanal and 6-phenoxyhexanal proceeded with
92 and 94% ees, respectively, under atmospheric pressure.
The effect of the solvent on enantioselectivity was examined
by using complex 3 as catalyst (Table 2) and the best enantiose-
lectivity was attained albeit with only modest yield, when the re-
action was carried out in tert-butyl methyl ether (TBME) (Entry
7). Fortunately, the chemical yield was improved and the selec-
tivity maintained, when the reaction was carried out in a 1:1
mixture of TBME and CH2Cl2 (Entry 8). Lowering the reaction
The nucleophilic addition of allylic organometallics to alde-
hydes or ketones such as the Hosomi–Sakurai reaction is a con-
ventional method for synthesis of homoallylic alcohols and its
asymmetric version has been extensively studied by using chiral
Lewis acid as catalyst.1,2 In 1991, Yamamoto and co-workers re-
ported a seminal study of this type of reaction, addition of allyl-
trimethylsilane catalyzed by a chiral acyloxy borane derived
from tartaric acid.3 Since then, many efficient methods for the
enantioselective addition of allylstannane and allylsilane deriv-
atives have been developed and good to high enantioselectivities
have been achieved in the reactions of both aromatic and aliphat-
ic aldehydes.4 Although many chiral Lewis acids have been used
as catalysts, chiral Ti(IV)–BINOL,5 Zr(IV)–BINOL,6 Ag(I)–
BINAP,7 In(III)–PYBOX8 and Rh(III)–BOX complexes9 are
among the most efficient ones. Especially, a bimetallic Ti-BI-
NOL complex served as excellent catalyst.10 In 2004, Cr(salen)
complex 1 (Figure 1) was found to catalyze enantioselective ad-
dition of allyltributylstannane to alkyl glyoxylates.11 Recently, 1
was further reported to catalyze addition of allyltributylstannane
to simple aldehydes with good enantioselectivity (up to 79% ee)
under high-pressure (10 kbar).12 We recently found that readily
available and manageable chiral Cr(salen) complexes 2 serve
as efficient Lewis acid catalysts for hetero-Diels–Alder13 and
Mukaiyama-aldol reactions.14,15 Moreover, the salen ligand
bearing a binaphthyl unit has been disclosed to attractively inter-
act with substrates through a weak bond interaction such as
CH–ꢀ interaction.16 Thus, we expected that complexes 2 would
also catalyze addition of allyltributylstannane to simple alde-
hydes under milder pressure in an enantioselective manner.
We first examined addition of allyltributylstannane to 3-
phenylpropanal under atmospheric pressure in the presence of
2a bearing the same counter anion, BF4ꢁ, as 1 and found that
it catalyzed the addition even at ꢁ20 ꢂC, albeit with modest
N
O
N
O
Cr+
N
O
N
Cr+
tBu
O
-
tBu
Ph Ph
BF4
tBu
tBu
1
X-
2a : X = BF4, 2b : X = SbF6
Ar1
N
Ar1
N
R
N
O
R
N
Cr+
Cr+
O
O
O
Ar2 Ar2
2''
Ph Ph
3
3'
-
-
SbF6
SbF6
3: Ar1 = Ar2 = Ph
6 : R = -(CH2)4-
7 : R = Ph
4: Ar1 = Ph, Ar2 = p-(C6H5)C6H4
5: Ar1 = Ph, Ar2 = H
Figure 1.
Table 1. Asymmetric addition of allyltributylstannane using
various Cr(salen) complexes as catalysts
Ph(CH2)2CHO
OH
*
cat. (5 mol%)
+
SnnBu3
CH Cl , −20 °C, 24 h
Ph(CH2)2
2
2
(1.1 equiv)
Entry
cat.
Yield/%a
ee/%b
Config.c
1
2
3
4
5
6
7
2a
2b
3
4
5
16
39
59
56
28
40
45
80
80
90
88
45
24
50
S
S
S
S
R
S
S
ꢁ
yield. In addition, complex 2b bearing SbF6 as the anion was
found to show better catalytic acꢁtivity. Thus, we examined the
addition using 3–7 bearing SbF6 anion as catalyst and found
that complex 3 bearing (R,R)-1,2-diphenylethylenediamine as
the diamine unit was the most effective catalyst for this reaction
in terms of enantioselectivity and chemical yield (Entry 3).
Complex 4 showed somewhat lower enantioselectivity (Entry
4). Complex 5 was less catalytically active and induced modest
enantioselectivity. However, the sense of asymmetric induction
by 5 was opposite to that by 3 or 4, indicating that the C200-aryl
6
7
aIsolated yield. bDetermined by HPLC analysis using chiral
stationary phase column (Daicel Chiralcel OD-H, Ref. 7).
cAbsolute configuration was determined by chiroptical
comparison (Ref. 7).
Copyright ꢀ 2005 The Chemical Society of Japan

Chemistry Letters Vol.34, No.6 (2005)
787
Table 2. Optimization of asymmetric addition of allyltributyl-
stannane to 3-phenylpropanal using 3 as catalyst
chromatographed on silica gel (hexane/AcOEt = 9:1) to give
the corresponding product in 80% yield. The enantiomeric
excess of the product was determined by HPLC analysis, as
described in the footnote to Table 1.
In conclusion, we were able to demonstrate that complex 3
catalyzes asymmetric addition of allyltributylstannane to simple
aldehydes under atmospheric pressure, though good substrates
were limited to nonbranched aldehydes.
Entry
Solvent
Temp/ꢂC Time/h Yield/%a ee/%b
1
2
3
4
5
6
7
8
9
CH2Cl2
CHCl3
(CH2Cl2)2
i-Pr2O
Et2O
ꢁ20
ꢁ20
ꢁ20
ꢁ20
ꢁ20
ꢁ20
ꢁ20
ꢁ20
ꢁ30
24
24
24
24
24
24
24
24
24
59
37
41
36
30
39
33
59
43
90
87
85
88
77
50
93
92
92
THF
TBME
TBME/CH2Cl2
TBME/CH2Cl2
Financial support from Banyu Pharmaceutical Co., and
Nissan Chemical Industries is gratefully acknowledged.
References and Notes
aIsolated yield. bDetermined by HPLC analysis using chiral
stationary phase column (Daicel Chiralcel OD-H, Ref. 7).
1
2
Y. Yamamoto and N. Asao, Chem. Rev., 93, 2207 (1993).
Recently, asymmetric addition of allyltrichlorosilanes to alde-
hydes in the presence of chiral Lewis base such as phosphor-
amide, formamide, N-oxide, and sulfoxide derivatives has also
been extensively studied: a) S. E. Denmark, D. M. Coe,
N. E. Pratt, and B. D. Griedel, J. Org. Chem., 59, 6161
(1994). b) K. Iseki, S. Mizuno, Y. Kuroki, and Y. Kobayashi,
Tetrahedron Lett., 39, 2767 (1998). c) M. Nakajima, M. Saito,
M. Shiro, and S. Hashimoto, J. Am. Chem. Soc., 120, 6419
(1998). d) A. Massa, A. V. Malkov, P. Kocovsky, and A.
Scettri, Tetrahedron Lett., 44, 7179 (2003).
temperature did not affect the selectivity.
Under the optimized conditions, the reactions of other alde-
hydes were examined (Table 3). The reactions of nonbranched
aliphatic aldehydes such as octanal and 6-phenoxyhexanal also
proceeded with high enantioselectivity (>90% ee, Entries 1–
5). However, the reactions of bulky aldehyde and conjugated
aldehyde were sluggish, though the reason is unclear. Even at
23 ꢂC, the reactions were considerably slow and modestly enan-
tioselective (Entries 6 and 7). A similar trend has been observed
in the reaction using Rh(III)-tetraaza complex as catalyst.17
Typical experimental procedure was exemplified by the re-
action of 3-phenypropanal and allyltributylstannane: Complex 3
(6.1 mg, 5 mol %) was dissolved in a mixture of CH2Cl2 (125
mL) and TBME (125 mL) under nitrogen. To the solution was
added 3-phenypropanal (13 mL, 0.10 mmol), and the mixture
was cooled to ꢁ20 ꢂC. Allyltributylstannane (34 mL, 0.11 mmol)
was added to the mixture and stirred for 3 days at the tempera-
ture. The reaction mixture was treated with sat. NaHCO3, stirred
for 30 minutes, dried (Na2SO4), and filtered. The filtrate was
3
4
K. Furuta, M. Mouri, and H. Yamamoto, Synlett, 1991, 561.
For a recent review, see: S. E. Denmark and J. Fu, Chem. Rev.,
103, 2763 (2003).
5
a) A. L. Costa, M. G. Piazza, E. Tagliavini, C. Trombini, and
A. Umani-Ronchi, J. Am. Chem. Soc., 115, 7001 (1993). b)
G. E. Keck, K. H. Tarbet, and L. S. Geraci, J. Am. Chem.
Soc., 115, 8467 (1993). c) S. Aoki, K. Mikami, M. Terada,
and T. Nakai, Tetrahedron, 49, 1783 (1993).
6
a) P. Bedeschi, S. Casolari, A. L. Costa, E. Tagliavini, and
A. Umani-Ronchi, Tetrahedron Lett., 36, 7897 (1995). b) S.
Casolari, P. G. Cozzi, P. A. Orioli, E. Tagliavini, and A.
Umani-Ronchi, Chem. Commun., 1997, 2123. c) H. Hanawa,
S. Kii, N. Asao, and K. Maruoka, Tetrahedron Lett., 41,
5543 (2000).
Table 3. Asymmetric allylation of various aldehydes using 3
as catalyst
7
a) A. Yanagisawa, H. Nakashima, A. Ishiba, and H.
Yamamoto, J. Am. Chem. Soc., 118, 4723 (1996). b) M.
Wadamoto, N. Ozasa, A. Yanagisawa, and H. Yamamoto,
J. Org. Chem., 68, 5593 (2003).
RCHO
+
3 (5 mol%)
OH
SnnBu3
TBME/ CH2Cl2, −20 °C, 3 days
R
(1.1 equiv)
8
9
L. Jun, J. Shun-Jun, T. Yong-Chua, and L. Teck-Peng, Org.
Lett., 7, 159 (2005).
Y. Motoyama, H. Narusawa, and H. Nishiyama, Chem.
Commun., 1999, 131.
Entry
R
Yield/%a ee/%b Config.c
1
Ph(CH2)2
n-C7H15
PhO(CH2)5
PhO(CH2)2
(CH3)3CCOO(CH2)5
c-C6H11
80
77
84
67
72
18
40
92
S
2d
3
92e
94
—
—
—
—
R
10 H. Hanawa, D. Uraguchi, S. Konishi, T. Hashimoto, and K.
Maruoka, Chem.—Eur. J., 9, 4405 (2003).
11 P. Kwiatkowski, W. Chaladaj, and J. Jurczak, Tetrahedron
Lett., 45, 5343 (2004).
12 The reaction was slow under atmospheric pressure: P.
Kwiatkowski, W. Chaladaj, and J. Jurczak, Synlett, 2005, 227.
13 K. Aikawa, R. Irie, and T. Katsuki, Tetrahedron, 57, 845
(2001).
14 a) Y. Matsuoka, R. Irie, and T. Katsuki, Chem. Lett., 32, 584
(2003). b) S. Onitsuka, Y. Matsuoka, R. Irie, and T. Katsuki,
Chem. Lett., 32, 974 (2003).
15 Y. Shimada, Y. Matsuoka, R. Irie, and T. Katsuki, Synlett,
2004, 57.
16 T. Hashihayata, T. Punniyamurthy, R. Irie, T. Katsuki, M.
Akita, and Y. Moro-oka, Tetrahedron, 55, 14599 (1999).
17 F. J. LaRonde and M. A. Brook, Can. J. Chem., 81, 1206
(2003).
4
5
6f
7f
94
94e
40e
53
Ph
R
b
aIsolated yield. Determined by HPLC analysis using chiral
stationary phase column (Daicel Chiralcel OD-H, Ref. 7), un-
c
less otherwise mentioned. Absolute configuration was deter-
mined by chiroptical comparison (Ref. 7). d10 mol % of 3 was
used. When 5 mol % of 3 was used, the yield and the ee of the
product were 56% and 92% ee, respectively. Determined by
e
HPLC analysis using chiral stationary phase column (Daicel
Chiralpak AS-H), after the product was converted into the cor-
responding 3,5-dinitrobenzoate (3,5-dinitrobenzoyl chloride,
triethylamine/dichloromethane). fReaction was carried out
at 23 ꢂC.
Published on the web (Advance View) May 7, 2005; DOI 10.1246/cl.2005.786