A novel chiral H′4-NOBIN schiff base for hetero-diels-alder reaction of danishefsky's diene with aldehydes

Article abstract of DOI:10.1055/s-2008-1042913

Novel chiral H′₄-NOBIN was synthesized in 66% yield through partial hydrogenation of 2-amino-2′-hydroxy-1,1′-binaphthyl, and the structure was proved via X-ray analysis of its salicylaldehyde Schiff base, which was tested in the enantioselectiv

Full text of DOI:10.1055/s-2008-1042913

LETTER
857
A Novel Chiral H¢4-NOBIN Schiff Base for Hetero-Diels–Alder Reaction of
Danishefsky’s Diene with Aldehydes
N
a
ovel Chiral
H¢
4-NiOBIN
n
Schiff Basesheng Li,*a,b Xiangyan Meng,b Hong Su,a Xiaohua Wu,b Dongcheng Xua,b
Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University,
Jinhua 321004, P. R. of China
Fax +86(579)82282610; E-mail: sky33@zjnu.cn
Department of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, P. R. of China
b
Received 26 October 2007
Abstract: Novel chiral H¢4-NOBIN was synthesized in 66% yield
through partial hydrogenation of 2-amino-2¢-hydroxy-1,1¢-binaph-
thyl, and the structure was proved via X-ray analysis of its salicyl-
aldehyde Schiff base, which was tested in the enantioselective
titanium-catalyzed hetero-Diels–Alder reaction of Danishefsky’s
diene with aldehydes. The reaction provided dihydropyranone in
moderate to high yield (up to 99%) and enantioselectivities (up to
84.5% ee).
X
Y
X
Y
4 X = Y = OH
1 X = Y = OH
2 X = Y = NH2
5 X = NH2, Y = OH
6 X = OH, Y = NH2
3 X = OH, Y = NH2
Key words: asymmetric catalysis, Schiff bases, Diels–Alder reac-
tions, heterocycles, titanium
Figure 1
the enantioselective hetero-Diels-Alder reaction (HDA)
Optically active 1,1¢-bi-2-naphthol (BINOL), 1,1¢-bi-2-
naphthylamine (BINAM), 2-amino-2¢-hydroxy-1,1¢-bi-
naphthyl (NOBIN), and their derivatives have been suc-
cessfully developed as chiral ligands for many
asymmetric reactions.1 Some results showed that the cat-
alysts derived from partially saturated 1,1¢-binaphthyl ex-
hibit higher efficiency and enantioselectivity for some
asymmetric reactions than those obtained from their par-
ent ligands, due to the steric and electronic modulations
on the binaphthyl backbone.2 The procedure of preparing
chiral H8-BINOL (1), H8-BINAM (2), H8-NOBIN (3) and
H4-BINOL (4, Figure 1) has been developed by using dif-
ferent catalysts and conditions, such as PtO2 (15 mol%) at
25 °C for 7 days (Cram et al.) and 10% Pd/C (10 mol%)
at room temperature for 2 days (Sigimura et al.) for 1,3 Ni/
Al alloy in dilute H2O–i-PrOH alkaline solution for 1-4
(Ding et al.),4 5% Pd/C (7 mol%) at 80 °C under 50-60
bar pressure for several hours for 1 and 2 (Börner et al.).5
Among these methods, the procedure of Börner provided
a practical way for synthesis of 1 and 2, but preparation of
3 using of Börner’s method was not reported. Our study
needs multigram scale of 3. The hydrogenation of (S)-
NOBIN were carried out according Börner’s procedure,
but the method provided (S)-5¢,6¢,7¢,8¢-tetrahydro-2-ami-
no-2¢-hydroxy-1,1¢-binaphthyl (H¢4-NOBIN, 5) in 66%
yield and 3 in 19% yield. To the best of our knowledge,
this is the first report on the synthesis of 5.6 In the present
work, we wish to report the details on the synthesis of 5
and its Schiff base-titanium complex used as catalyst for
between Danishefsky’s diene and aldehydes.
The NOBIN was found to be an excellent chiral ligand for
asymmetric reactions and its synthesis has been well de-
veloped.7,8 The two naphthalene rings of NOBIN, unlike
the C2-symmetric BINOL and BINAM, have slightly dif-
ference in terms of electron density due to the difference
of hydroxyl and amino groups. The difference of the elec-
tronic properties makes the selective hydrogenation possi-
ble. The hydrogenation of (S)-NOBIN was carried out
with 5% Pd/C (5 mol%) as catalyst at 80 °C under 80 bar
of hydrogen pressure in ethanol (Scheme 1 and Table 1).9
Shorter reaction time gave a mixture of NOBIN, 3 and 5
(Table 1, entries 1 and 2). Higher catalyst loading im-
proved the yield of 3 (Table 1, entry 4). The complete
conversion of starting material needed 10 hours (Table 1,
entry 3). The hydrogenation product was isolated in 66%
yield after purification with column chromatography. The
1H NMR spectrum of the product showed that the ratio of
aromatic protons to alkyl protons is 1:1 rather than the ex-
pected value of 1:4 for octahydrobinaphthyl derivatives,
and the 13C NMR spectrum showed only four carbon at-
Table 1 Catalytic Hydrogenation of (S)-NOBINa
Entry
Time
(h)
Ratio of 3/5/
Yield of 3 Yield of 5
NOBINb
(%)c
(%)c
1
5
7
9:58:33
15:70:15
26:74:0
45:55:0
–
41
2
7
62
3
10
10
18
33
66
4d
48
SYNLETT 2008, No. 6, pp 0857–0860
x
x.
x
x.
2
0
0
8
Advanced online publication: 11.03.2008
DOI: 10.1055/s-2008-1042913; Art ID: W19407ST
© Georg Thieme Verlag Stuttgart · New York
a Reaction conditions: 0.57 g NOBIN, 0.2 g 5% Pd/C, 80 bar of H2
pressure, 80 °C, 15 mL EtOH.
b Determined by GC.
c Isolated yield. The ee >99.5% was determined by chiral HPLC using
Chiralcel AD-H or OJ-H column.
d The amount of 0.4 g 5% Pd/C was used.

858
X. Li et al.
LETTER
NH2
OH
NH2
OH
NH2
OH
Pd/C, H2
+
80 bar, 80 °C, EtOH
(S)-NOBIN
5
major
3 minor
OH
N
toluene
reflux, 16 h
+
5
OH
HO
CHO
7
Scheme 1 Synthesis of (S)-5 and ligand (S)-7.
oms at the high field region. The result indicated that four The HAD reaction between dienes and carbonyl deriva-
hydrogen atoms were added on the non-C2-symmetric tives provides one of the most direct methods for the con-
NOBIN. Thus, two different compounds were at least struction of substituted 2,3-dihydro-4H-pyran-4-ones,
formed: 5¢,6¢,7¢,8¢-tetrahydro-2-amino-2¢-hydroxy-1,1¢- which have extensively applied in synthesis of natural or
binaphthyl (5, H¢4-NOBIN) and 5,6,7,8-tetrahydro-2-ami- unnatural products.12 Recently, the chiral NOBIN-derived
no-2¢-hydroxy-1,1¢-binaphthyl (6, H4-NOBIN). The final Schiff base–titanium complexes were reported to be ef-
determination that the molecular structure was 5 and not 6 fective catalysts for the enantioselective HDA reaction of
was ascertained by characterization of its salicylaldehyde Danishefsky’s diene and aldehydes by Ding et al.7b With
Schiff base using X-ray crystallographic analysis.
the novel ligand 7 in hand, we tested its asymmetric in-
duction in the HDA reaction. Naproxen was not the choice
of additive due to a change of configuration of the ligand.
Thus, a number of acids were screened (Table 2). The re-
sults showed that the additive could remarkably improve
the yields and ee, and the additive 2-naphthoic acid was
found to be the best.
The HDA reaction of Danishefsky’s diene and a variety of
aldehydes, including aromatic, a,b-unsaturated and ali-
phatic aldehydes, was carried out with 2-naphthoic acid as
additive in the presence of the Ti-(S)-7 complex
(Table 3).13 The results showed that aromatic aldehydes
provided higher yield and enantiomeric excess than ali-
phatic aldehydes. The electronic effect of substituents of
aromatic ring on reactivity was obvious. The presence of
either electron-withdrawing groups such as Br, Cl, CF3, to
NO2 (Table 3, entries 2-5), or electron-donating capabil-
ity from 3-MeO to 3-Me (Table 3, entries 6 and 7), result-
ed in lower enantioselectivities. Furfural and trans-
cinnamaldehyde afforded the corresponding dihydropy-
rones with moderate enantioselectivity and high yield
(Table 3, entries 8 and 9). The HDA reaction of cyclohex-
anecarboxaldehyde and diene provided dihydropyrone in
modest enantioselectivity and yield (Table 3, entry 10).
The results obtained showed that the enantioselectivities
were inferior to its parent catalyst.
Figure 2 Molecular structure of (R)-7.
The Schiff base (R)-7 was synthesized by condensation of
(R)-5 with salicylaldehyde in refluxing toluene
(Scheme 1).10 The structure of (R)-5 was confirmed by the
analysis of X-ray crystal structure of (R)-7.11 As shown in
Figure 2, the C–C bond lengths of C5-C6, C6-C7, C7-
C8, and C9-C10 are between 1.49-1.52 Å. The dihedral
angle of the two binaphthyl rings (99.01°) is larger than its
parent Schiff base (75.61°), and the dihedral angle of imi-
no naphthyl ring and salicylidene phenyl ring (0.72°) is
smaller than its parent Schiff base (23.51°).7b The short
distance of N1-H(O2) (1.78 Å) suggested that the imino
nitrogen atom formed a strong intramolecular hydrogen
bond with the hydroxy group of salicylidene moiety rather
than that of naphthyl unit.
In summary, novel chiral (S)-H¢4-NOBIN was prepared
by partial hydrogenation of (S)-NOBIN, and the structure
was determined by X-ray crystal structure analysis. The
(S)-H¢4-NOBIN-derived Schiff base was tested in the
enantioselective titanium-catalyzed HDA reaction of
Danishefsky’s diene and aldehydes. The reaction provid-
Synlett 2008, No. 6, 857–860 © Thieme Stuttgart · New York

LETTER
Novel Chiral H′4-ΝΟΒΙΝ Schiff Base
859
Table 2 Effect of Various Carboxylic Acid Additives on the Enan-
Table 3 Asymmetric HDA Reaction of Danishefsky’s Diene with
Aldehydes in the Presence of (S)-7a
tioselectivity of the Reactiona
OMe
OMe
1. (S)-7–Ti
O
O
1. (S)-7–Ti, 2
additive
RCHO
+
PhCHO
+
*
2. CF3CO2H
2. CF3CO2H
O
Ph
O
R
Me3SiO
Me3SiO
Entry Additive
Yield (%)b ee (%)c
Entry
R
Yield (%)b
Ee (%)c
66.4 (S)
84.5
1d
2
3
4
5
6
7
8
9
–
43
97
99
82
76
83
75
76
80
81
41.8 (S)
63.8 (S)
69.2 (S)
64.4 (S)
44.6 (S)
53.2 (S)
63.9 (S)
44.3 (S)
65.7 (S)
52.4 (S)
54.0 (S)
62.3 (S)
1
2
Ph
98
99
99
99
96
80
89
88
91
59
Naproxen
4-BrC6H4
2-Naphthoic acid
3
4-ClC6H4
79.2
Benzoic acid
4
4-CF3C6H4
4-O2NC6H4
3-MeC6H4
3-MeOC6H4
Fur-2-yl
72.8
o-Chlorobenzoic acid
m-Chlorobenzoic acid
p-Chlorobenzoic acid
p-Bromobenzoic acid
p-Fluorobenzoic acid
5
60.9
6
45.1
7
70.3
8
38.4
9
trans-Cinnamyl
Cyclohexyl
61.78
11.0 (R)
10
p-Trifluoromethylbenzoic acid
10
a All of the reactions were carried out with (S)-7/Ti(Oi-Pr)4/2/
substrate = 0.2:0.1:0.05:1 in toluene in the presence of 4 Å MS at r.t.
for 12 h.
11
12
(S)-2-Methoxy-2-phenylacetic acid 95
1-Adamantanecarboxylic acid 93
b Isolated yields.
a All of the reactions were carried out with (S)-7/Ti(Oi-Pr)4/additive/
substrate = 0.2:0.1:0.05:1 in toluene in the presence of 4 Å MS at r.t.
for 12 h.
c The ee were determined by HPLC on Chiralcel OD-H. Absolute
configurations were determined by comparison of specific rotations
with literature data.
b Isolated yields.
c The ee values were determined by HPLC on Chiralcel OD-H. Abso-
lute configurations were determined by comparison of specific rota-
tions with literature data.
M. C. K.; Chan, A. S. C. Tetrahedron 2002, 58, 8799.
(e) Chan, A. S. C.; Zhang, F.-Y.; Yip, C.-W. J. Am. Chem.
Soc. 1997, 119, 4080. (f) Zhang, F.-Y.; Pai, C.-C.; Chan, A.
S. C. J. Am. Chem. Soc. 1998, 120, 5808. (g) Uemura, T.;
Zhang, X.; Matsumura, K.; Sayo, N.; Kumobayashi, H.;
Ohta, T.; Nozaki, K.; Takaya, H. J. Org. Chem. 1996, 61,
5510. (h) Xiao, J.; Nefkens, S. C. A.; Jessop, P. G.; Ikariya,
T.; Noyori, R. Tetrahedron Lett. 1996, 37, 2813.
d An additive was not used.
ed dihydropyranone in moderate to high yields and up to
84.5% ee. Further studies of the derivatives of (S)-H¢4-
NOBIN as a ligand in asymmetric synthesis are currently
under investigation.
(i) McDougal, N. T.; Schaus, S. E. J. Am. Chem. Soc. 2003,
125, 12094. (j) Xu, Q.; Gu, X.; Liu, S.; Dou, Q.; Shi, M.
J. Org. Chem. 2007, 72, 2240.
Acknowledgment
(3) (a) Cram, D. J.; Helgeson, R. C.; Peacock, S. C.; Kaplan, L.
J.; Domeier, L. A.; Moreau, P.; Koga, K.; Mayer, J. M.;
Chao, Y.; Siegel, M. G.; Hoffman, D. H.; Sogah, G. D. Y. J.
Org. Chem. 1978, 43, 1930. (b) Sugimura, T.; Yamada, H.;
Inoue, S.; Tai, A. Tetrahedron: Asymmetry 1997, 8, 649.
(4) (a) Guo, H.; Ding, K. Tetrahedron Lett. 2000, 41, 10061.
(b) Shen, X.; Guo, H.; Ding, K. Tetrahedron: Asymmetry
2000, 11, 4321.
The subject was supported by the Natural Science Foundation of
Zhejiang Province (Y405013). Dr. Yunjie Luo of Ningbo Institute
of Technology, Zhejiang University is thanked for the X-ray analy-
sis.
References and Notes
(5) (a) Korostylev, A.; Tararov, V. I.; Fischer, C.; Monsees, A.;
Börner, A. J. Org. Chem. 2004, 69, 3220. (b)Very recently,
Motoyama reported hydrogenation of BINOL and BINAM
using Ru/CNF-P as catalyst. See: Takasaki, M.; Motoyama,
Y.; Yoon, S.-H.; Mochida, I.; Nagashima, H. J. Org. Chem.
2007, 72, 10291.
(6) (a) Ding, K.; Guo, H.; Li, X.; Yuan, Y.; Wang, Y. Top.
Catal. 2005, 35, 105. (b) Ding, K.; Li, X.; Ji, B.; Guo, H.;
Kitamura, M. Curr. Org. Synth. 2005, 2, 499.
(1) (a) Ojima, I. Catalytic Asymmetric Synthesis, 2nd ed.;
Wiley: New York, 2000. (b) Au-Yeung, T. T.-L.; Chan, S.-
S.; Chan, A. S. C. Adv. Synth. Catal. 2003, 345, 537.
(2) (a) Zeng, Q.; Liu, H.; Cui, X.; Mi, A.; Jiang, Y.; Li, X.; Choi,
M. C. K.; Chan, A. S. C. Tetrahedron: Asymmetry 2002, 13,
115. (b) Li, X.; Jia, X.; Lu, G.; Au-Yeung, T. T.-L.; Lam, K.-
H.; Lo, T. W. H.; Chan, A. S. C. Tetrahedron: Asymmetry
2003, 14, 2687. (c) Zeng, Q.-H.; Hu, X.-P.; Duan, Z.-C.;
Liang, X.-M.; Zheng, Z. Tetrahedron: Asymmetry 2005, 16,
1233. (d) Zeng, Q.; Liu, H.; Mi, A.; Jiang, Y.; Li, X.; Choi,
Synlett 2008, No. 6, 857–860 © Thieme Stuttgart · New York

860
X. Li et al.
LETTER
chromatography on silica gel (316 mg, 80.3% yield); mp
(7) (a) Yuan, Y.; Li, X.; Sun, J.; Ding, K. J. Am. Chem. Soc.
2002, 124, 14866. (b) Yuan, Y.; Long, J.; Sun, J.; Ding, K.
Chem. Eur. J. 2002, 8, 5033. (c) Carreira, E. M.; Singer, R.
A.; Lee, W. J. Am. Chem. Soc. 1994, 116, 8837. (d) Hu, X.;
Chen, H.; Zhang, X. Angew. Chem. Int. Ed. 1999, 38, 3518.
(e) Vyskocil, S.; Jaracz, S.; Smrcina, M.; Sticha, M.; Hanus,
V.; Polasek, M.; Kocovsky, P. J. Org. Chem. 1998, 63, 7727.
(8) (a) Ding, K.; Xu, Q.; Wang, Y.; Liu, J.; Yu, Z.; Du, B.; Wu,
Y.; Koshima, H.; Matsuura, T. Chem. Commun. 1997, 693.
(b) Ding, K.; Wang, Y.; Yun, H.; Liu, J.; Wu, Y.; Terada, M.;
Okubo, Y.; Mikami, K. Chem. Eur. J. 1999, 5, 1734.
(c) Smrčina, M.; Lorenc, M.; Hanuš, V.; Sedmera, P.;
Kočovský, P. J. Org. Chem. 1992, 57, 1917. (d) Körber, K.;
Tang, W.; Hu, X.; Zhang, X. Tetrahedron Lett. 2002, 43,
7163.
166-168 °C, [a]D20 -118 (c 0.2, THF). 1H NMR (400 MHz,
CDCl3): d = 1.54-1.58 (m, 2 H), 1.67-1.70 (m, 2 H), 1.99-
2.10 (m, 1 H), 2.14-2.17 (m, 1 H), 2.76-2.81 (m, 2 H), 4.27
(s, 1 H), 6.84-6.89 (m, 3 H), 7.11-7.13 (m, 1 H), 7.27-7.32
(m, 3 H), 7.48-7.52 (m, 2 H), 7.59-7.61 (m, 1 H), 8.01-
8.03 (m, 1 H), 8.51-8.53 (m, 1 H), 8.73 (s, 1 H), 12.3 (s, 1
H). 13C NMR (100 MHz, CDCl3): d = 22.9, 23.0, 23.1, 27.4,
29.3, 112.7, 117.2, 117.4, 118.8, 119.3, 122.1, 125.7, 126.3,
127.2, 127.5, 128.2, 129.7, 130.2, 130.3, 132.3, 132.7,
132.9, 133.1, 136.4, 143.9, 150.6, 161.3, 162.1. IR (KBr):
3381, 3053, 2928, 1610, 1569 cm–1. Anal. Calcd for
C27H23NO2: C, 82.42; H, 5.89; N, 3.56. Found: C, 82.39; H,
5.88; N, 3.58.
(11) Crystallographic data (excluding structure factors) for the
structures in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary
publication number CCDC 658558 [(R)-7]. These data can
be obtained free of charge via www.ccdc.cam.ac.uk/conts/
retrieving.html [or from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
+44(1223)336033 or e-mail: deposit@ccdc.cam.ac.uk.].
(12) (a) Fan, Q.; Lin, L.; Liu, J.; Huang, Y.; Feng, X.; Zhang, G.
Org. Lett. 2004, 6, 1285. (b) Yang, W.; Shang, D.; Liu, Y.;
Du, Y.; Feng, X. J. Org. Chem. 2005, 70, 8533. (c) Tietze,
L. F.; Kettschau, G. Top. Curr. Chem. 1997, 189, 1.
(13) General Procedure for Catalytic Enantioselctive Hetero-
Diels–Alder Reaction
(9) Synthesis of (S)-5¢,6¢,7¢,8¢-tetrahydro-2-amino-2¢-
hydroxy-1,1¢-binaphthyl (S)-5
(S)-NOBIN (0.57 g, 2 mmol), 5% Pd/C (0.21 g), and EtOH
(15 mL) were placed into a 100 mL autoclave and stirred
under 80 bar hydrogen pressure at 80 °C for 10 h. The
reaction mixture was cooled to r.t., the catalyst was filtered
off, and washed with THF (2 × 10 mL). The combined
filtrates were concentrated in vacuum to give a mixture of 3
and 5, which was submitted to column chromatographic
separation on silica gel with hexane–EtOAc (9:1) as eluent
to afford (S)-5 (382 mg, 66% yield) as a foam solid with
>99.5% ee [HPLC on an AD-H column with hexane–i-PrOH
(90:10) as eluent, 1 mL min–1, tR = 13.88 (R) min, tR = 22.73
min (S)]; mp 113–115 °C; [a]D20 –59 (c 1, THF). 1H NMR
(400 MHz, CDCl3): d = 1.60–1.63 (m, 2 H), 1.70-1.74 (m,
2 H), 2.13-2.18 (m, 1 H), 2.21-2.26 (m, 1 H), 2.77-2.80
(m, 2 H), 3.76 (s, 2 H), 4.59 (s, 1 H), 6.80 (d, 1 H, J = 8.4
Hz), 7.09-7.17 (m, 3 H), 7.26-7.30 (m, 2 H), 7.74 (d, 2 H,
J = 8.4 Hz). 13C NMR (100 MHz, CDCl3): d = 23.0, 23.1,
26.8, 29.3, 110.3, 112.8, 117.9, 120.5, 122.6, 127.2, 128.2,
128.3, 129.8, 130.1, 130.4, 133.5, 137.7, 142.7, 151.4. IR
(KBr): 3447, 3376, 3052, 2926, 1619, 1471 cm–1. Anal.
Calcd for C20H19NO: C, 83.01; H, 6.62; N, 4.84. Found: C,
82.94; H, 6.68; N, 4.80.
A mixture of (S)-Schiff Base (19.7 mg, 0.05 mmol), Ti(Oi-
Pr)4 in toluene (0.25 M, 0.1 mL, 0.025 mmol) and activated
powdered 4 Å MS (40 mg) in toluene (1 mL) was stirred for
2 h at 50 °C. The red solution was cooled to r.t. and naproxen
(5.8 mg, 0.025 mmol), aldehyde (0.25 mmol), and
Danishefsky’s diene (60 mL, 0.3 mmol) were added
sequentially. The mixture was stirred for 12 h at r.t. before
quenched with TFA (0.2 mL). After stirring for additional 30
min, the mixture was neutralized with sat. NaHCO3 (3 mL).
After filtration through a plug of Celite, the organic layer
was separated and the aqueous layer was extracted with
EtOAc (3 × 5 mL). The combined organic layers were dried
over anhyd Na2SO4 and concentrated in vacuo. The residue
was purified by flash chromatography (EtOAc-hexane, 1:4)
to give the products for 1H NMR and HPLC analysis.
(10) Synthesis of Ligand (S)-7
Compound (S)-5 (285 mg, 0.1 mmol) and salicylaldehyde
(122 mg, 0.12 mmol) were stirred in toluene (20 mL) and the
mixture was heated to reflux for 16 h. The solvent was
removed in vacuo and the product was isolated by flash
Synlett 2008, No. 6, 857–860 © Thieme Stuttgart · New York