Enantioselective catalysis. Part 143: Astonishingly high enantioselectivity in the transfer hydrogenation of acetophenone with 2-propanol using Ru complexes of the Schiff base derived from (S)-2-amino-2′-hydroxy-1,1′-binaphthyl (NOBIN) and 2-pyridinecarbaldehyde

Article abstract of DOI:10.1016/S0957-4166(02)00029-0

A series of bidentate and tridentate (S)-NOBIN derivatives was synthesised and tested as chiral ligands in the Ru-catalysed enantioselective transfer hydrogenation of acetophenone with 2-propanol. Despite the similarities in chemical structure, only the imine derived from (S)-NOBIN and 2-pyridinecarbaldehyde and the corresponding amine (obtained by NaBH₄ reduction of the imine) afforded (S)-1-phenylethanol in nearly quantitative yields and outstanding enantioselectivities of up to 97% e.e.

Full text of DOI:10.1016/S0957-4166(02)00029-0

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 13 (2002) 37–42
Enantioselective catalysis. Part 143: Astonishingly high
enantioselectivity in the transfer hydrogenation of acetophenone
with 2-propanol using Ru complexes of the Schiff base derived
from (S)-2-amino-2%-hydroxy-1,1%-binaphthyl (NOBIN) and
2-pyridinecarbaldehyde†
Henri Brunner,* Frauke Henning and Matthias Weber
Institut fu¨r Anorganische Chemie, Universita¨t Regensburg, D-93040 Regensburg, Germany
Received 14 December 2001; accepted 16 January 2002
Abstract—A series of bidentate and tridentate (S)-NOBIN derivatives was synthesised and tested as chiral ligands in the
Ru-catalysed enantioselective transfer hydrogenation of acetophenone with 2-propanol. Despite the similarities in chemical
structure, only the imine derived from (S)-NOBIN and 2-pyridinecarbaldehyde and the corresponding amine (obtained by NaBH4
reduction of the imine) afforded (S)-1-phenylethanol in nearly quantitative yields and outstanding enantioselectivities of up to
97% e.e. © 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
thalene-2-carboxylate with 2-methoxy-1-naphthylmag-
nesium bromide to give (S)-2%-methoxy-1,1%-binaph-
thyl-2-carboxylic acid (S)-1 after hydrolysis. Subse-
quent Curtius rearrangement of (S)-1 leads to (S)-2-
amino-2%-methoxy-1,1%-binaphthyl (S)-2, NOMBIN,3
which can be submitted to BBr3 cleavage of the methyl
ether to afford (S)-3, (S)-NOBIN, in 92% yield, a new
approach which we disclose herein (Scheme 1).
(S)-2-Amino-2%-hydroxy-1,1%-binaphthyl (NOBIN) can
be synthesised by the unsymmetrical oxidative coupling
of the carcinogenic 2-naphthylamine with 2-naphthol
and subsequent resolution.1,2 An alternative synthesis
involves the diastereoselective nucleophilic aromatic
substitution of (−)-menthyl 1-(−)-menthoxynaph-
Scheme 1. Synthesis of (S)-3: (a) (i) SOCl2, reflux 4 h, (ii) NaN3, acetone, water, rt to 0°C, (iii) THF, water, reflux, 12 h, 70%;
(b) BBr3, methylene chloride, 92%.
* Corresponding author. Fax: +49-941/943-4439; e-mail: henri.brunner@chemie.uni-regensburg.de
† For Part 142, see: Brunner, H.; Scho¨nherr, M.; Zabel, M. Tetrahedron: Asymmetry 2001, 12, 2671–2675.
0957-4166/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(02)00029-0

38
H. Brunner et al. / Tetrahedron: Asymmetry 13 (2002) 37–42
As the metal precursor Ru(PPh3)3Cl2 itself has low
2. Results and discussion
catalytic activity (entry 20), there is no ligand accelera-
tion and no ligand influence with (S)-2–(S)-5. The same
is true for the Schiff bases (S)-6 and (S)-9 (entries 5
and 8). Compound (S)-7 gave a low conversion accom-
panied by chiral induction just outside the limits of
error (entry 6) and the Schiff base (S)-10, derived from
(S)-NOMBIN and 2-formylphenyl(diphenyl)phosphine,
afforded (R)-1-phenylethanol with 15% e.e. (entry 9).
Amazingly, the Schiff base (S)-8, derived from (S)-
NOBIN and 2-pyridinecarbaldehyde, yielded (S)-1-
phenylethanol in 97% e.e. (entry 7). Since the methoxy
derivative (S)-9 does not have any influence on the in
situ catalyst, the OH group of (S)-8 must be essential.
(S)-8 presumably binds to the metal atom as a pheno-
late. Inspection of Scheme 3 and Table 1 shows that
(S)-8 in combination with Ru(PPh3)3Cl2 is a unique
system affording outstanding enantioselectivities in the
transfer hydrogenation of acetophenone. Interestingly,
with the amine (S)-11, which is the reduction product
of imine (S)-8, the same high enantioselectivity was
obtained (entry 10).
By methylation of the hydroxyl group and/or the amine
group of (S)-NOBIN the O- and N-methylated ligands
(S)-4 and (S)-54 were obtained (Scheme 2).
We prepared the imine derivatives (S)-6,5 (S)-8,6 (S)-10
from (S)-NOBIN and (S)-7, (S)-9 from (S)-NOMBIN
by reaction with salicylaldehyde, 2-pyridinecarbalde-
hyde and 2-formylphenyl(diphenyl)phosphine. The lig-
and (S)-11 was obtained from (S)-8 by NaBH4
reduction (Scheme 3). We used the starting materials
(S)-2–(S)-5, the Schiff base ligands (S)-6–(S)-10 and
the amine (S)-11 together with the procatalyst
Ru(PPh3)3Cl2 in the enantioselective transfer hydro-
genation of acetophenone with 2-propanol. The in situ
catalysts with binaphthyls (S)-2–(S)-5 gave conversions
below 10% and racemic 1-phenylethanol product (Table
1, entries 1–4).
In order to increase the catalytic activity of (S)-8 and
(S)-11 several parameters were varied. Changing the
ratio of metal to ligand to substrate from 1/1.1/200 to
1/1.1/100 and 1/1.1/50 resulted in an increase in the
yield, with the enantiomeric excess remaining excellent
(entries 11–14 and 19). With the ratio 1/1.1/50 some
precipitation of the catalyst occurred probably due to
Scheme 2. The methylated compounds (S)-4 and (S)-5.
Scheme 3. Imines (S)-6–(S)-10 and amine (S)-11 derived from (S)-NOBIN and (S)-NOMBIN.

H. Brunner et al. / Tetrahedron: Asymmetry 13 (2002) 37–42
39
Table 1. Enantioselective transfer hydrogenation of acetophenone in presence of different (S)-NOBIN-derived Ligandsa
Entry
Ligand
Ratiob
Temp. (°C)
Time (h)
Yield (%)
E.e. (%)
1
2
3
4
5
6
7
8
(S)-2
(S)-3
(S)-4
(S)-5
(S)-6
(S)-7
(S)-8
(S)-9
(S)-10
(S)-11
(S)-8
(S)-11
(S)-8
(S)-8
(S)-8
(S)-8
(S)-8
(S)-8
(S)-8
–
1/1.1/1/200
1/1.1/2.1/200
1/1.1/1/200
1/1.1/2.1/200
1/1.1/3.1/200
1/1.1/2.1/200
1/1.1/2.1/200
1/1.1/1/200
28
28
28
28
28
28
28
28
28
28
28
28
28
28
50
83
28
28
50
28
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
1
6.4/6.4
3.6/5.2
5.8/8.9
4.0/16.5
1.2/0.8
8.6/4.3
22.8/22.6/25.1
2.3/3.7
20.4/20.8
85.7
94.3
94.3
88.3/86.0
96.4
97.7/96.9/98.2/96.4
93.5
31.4
37.7
98.6/97.0/98.1
3.5/5.7
rac.
rac.
rac.
rac.
rac.
2.6(S)/4.4(S)
97.1(S)/97.2(S)/96.6(S)
rac.
14.1(R)/15.9(R)
96.3(S)
95.7(S)
96.7(S)
96.3(S)/95.9(S)
95.2(S)
90.5(S)/88.1(S)/92.4(S)/93.8(S)
52.0(S)
97.8(S)
97.8(S)
81.1(S)/86.2(S)/91.9(S)
–/–
9
1/1.1/1/200
10
11
12
13
14
15
16
17
18
19
20
1/1.1/3.2/200
1/1.1/2.1/100
1/1.1/3.2/100
1/1.1/2.1/50
1/1.1/2.5/50
1/1.1/2.1/200
1/1.1/2.1/200
1/1.1/1.6/200
1/1.1/3.1/200
1/1.1/2.1/100
1/–/2.5/200c
15
15
15
15
a Representative procedure for entries 1–10: All experiments were performed under an inert nitrogen atmosphere using standard Schlenk
techniques and absolute solvents. The ligand (9.4 mmol) was dissolved in 2-propanol (10.4 mL) under N2 and a solution of KOtBu in 2-propanol
(0.95 mL of 0.01 mol/L) was added for each hydroxy group of the ligand. Ru(PPh3)3Cl2 (8.2 mg, 8.6 mmol) dissolved in 2-propanol (5 mL), was
added. The solution was stirred at room temperature for 1.5 h to accomplish the formation of the catalyst. Then, the reaction vessel was
thermostated to 28°C. Addition of acetophenone (0.2 mL) afforded a substrate concentration of 0.1 mol/L. The reaction was started by adding
another 0.86 mL of the 0.01 mol/L KOtBu solution. After 15 h the reaction was stopped by addition of 0.1 mol/L solution of acetic acid in
2-propanol (0.30 mL). After removal of the solvent, acetophenone and 1-phenylethanol were isolated by bulb-to-bulb distillation. The yield and
enantiomeric excess were determined by quantitative GC on a CP-Chirasil-Dex-CB-Column using biphenyl as an internal standard.
b Ratio of metal to ligand to base (KOtBu) to substrate.
c Base KOH.
Andersson. Taking catalyst deterioration and a decreas-
ing substrate concentration into account, turnover fre-
quencies can be calculated at 50% conversion.8 In this
respect the ligands (S)-8 and (S)-11 display turnover
frequencies of 25 and 10 h−1.
its high concentration. Increasing the temperature
raised the catalytic activity. At 50°C the enantiomeric
excess decreased, but only slightly (entries 15 and 19),
higher temperatures resulted in lower enantioselectivity
(entry 16). Varying the amount of base affected the
yield adversely but not the enantioselectivity of the
reaction (entries 14, 17 and 18).
At the beginning of the reaction the imine ligand (S)-8
displayed a higher activity than the amine ligand (S)-
11, for which an almost linear behaviour conversion/
time up to 70% conversion was observed. With
proceeding conversion the activity of the imine system
decreased and after 12 h reaction time the performance
of the amine system was very close to it. The decrease
in reaction rate for the imine system may result from
slow but steady catalyst decomposition (a yellow pre-
cipitate formed from the reddish–brown solution). On
the other hand, when forming the catalyst from the
amine (S)-11, base and Ru(PPh3)3Cl2, the colour of the
solution changed from brown to yellow and some yel-
low precipitate was formed initially, which disappeared
during the reaction, presumably increasing the catalyst
concentration.
We monitored the performance of ligands (S)-8 and
(S)-11 during the catalysis by analysing aliquots of the
reaction mixture with time. In both cases the conver-
sions reached 94% after 15 h reaction time (Fig. 1),
resulting in a turnover number of 94 and a turnover
frequency of 6 h−1. Noyori et al. reported 95% conver-
sion with a catalyst generated in situ from [(h6-
mesitylene)RuCl2] and (S,S)-TsDPEN at a substrate to
catalyst ratio of 200/1 under otherwise identical condi-
tions.7 This corresponds to a turnover number of 190
and a turnover frequency of 13 h−1. The highest
turnover frequencies of up to 3000 h−1 at room temper-
ature with excellent enantioselectivities were achieved
by Andersson et al. employing [(h6-p-cymene)RuCl2]
and a bidentate chiral ligand.8 We used Ru(PPh3)3Cl2
and potentially tridentate ligands. Therefore, our cata-
lysts are not analogous to those of Noyori and
In Table 1, entries 7 and 10, the activity of the catalytic
system with (S)-11 seems to be a little higher than that

40
H. Brunner et al. / Tetrahedron: Asymmetry 13 (2002) 37–42
Figure 1. Transfer hydrogenation of acetophenone with Ru(PPh3)3Cl2, KOtBu and the ligands (S)-8/(S)-11 in 2-propanol (52 mL)
at 28°C. Ratio Ru:ligand:base:substrate=1:1.1:2.1(S)-8/3.2(S)-11:100. The catalyst was prepared by stirring the components at
28°C for 1.5 h. Addition of acetophenone (0.6 mL, 5.1 mmol) gave a substrate concentration of 0.1 mol/L. During the catalysis
aliquots of 2.5 mL were diluted with 2.5 mL of petroleum ether 40–60, filtered over silica (washing with 1 mL of petroleum ether)
and analysed by quantitative GC.
bifunctional catalysis according to Noyori is
operating.12,13
of the (S)-8 system. However, entries 11 and 12 show
that their activities are almost identical and, according
to Fig. 1, the (S)-8 system is even more active than the
(S)-11 system. We attribute these inconsistencies to the
fact that the components of the in situ catalysts had to
be weighed in separately, effecting scattering of the
results. Thus, it is an open question as to whether the
imine is reduced to the amine (ruthenium complexes are
known to catalyse the transfer hydrogenation of
imines9–11) to give the active catalyst and metal–ligand
3. Experimental
1H NMR spectra: Bruker ARX 400 (400 MHz) and AC
250 (250 MHz) with TMS as internal reference. 31P
NMR spectra: Bruker ARX 400 (162 MHz) with
H3PO4 as external reference. (S)-1,3 (S)-23 and (S)-54
were synthesised according to the literature.

H. Brunner et al. / Tetrahedron: Asymmetry 13 (2002) 37–42
41
3.1. (S)-2-Amino-2%-hydroxy-1,1%-binaphthyl (S)-3
warming in vacuo. The crude product was purified as
indicated for the individual compounds.
A solution of (S)-2 (8.0 g, 26.8 mmol) in CH2Cl2 (50
mL) at −15°C was treated with BBr3 (3.0 mL, 7.9 g,
31.5 mmol). After stirring for 1 h the solution was
allowed to warm to room temperature. To the white
suspension cold water (20 mL) was added and with
cooling 2N aqueous HCl (20 mL). The remaining
suspension was extracted with diethyl ether (3×250
mL). The organic phases were collected and washed
with 2N aqueous Na2CO3 and water and dried with
Na2SO4. Removal of the solvent afforded the crude
product. After recrystallisation from benzene (S)-3 was
obtained as white needles (7.0 g, 92%). Mp 168–170°C;
[h]2D1=−117 (c 1.00, THF). Anal. calcd for C20H15NO
(285.3): C, 84.19; H, 5.30; N, 4.91. Found: C, 84.13; H,
5.20; N, 4.90%; 1H NMR (400 MHz, CDCl3): l 7.93 (d,
3.3.1. (S)-2-(2-Hydroxybenzylideneamino)-2%-hydroxy-
1,1%-binaphthyl (S)-65. Recrystallisation from benzene
yielded (S)-6 as orange crystals (875 mg, 45%). Mp
221–223°C; [h]2D1=−179 (c 0.96, benzene). Anal. calcd
for C27H19NO2 (389.5): C, 83.27; H, 4.92; N, 3.60.
1
Found: C, 82.89; H, 4.90; N, 3.38%; H NMR (400
MHz, CDCl3): l 12.01 (s, 1H, OH), 8.70 (s, 1H,
3
NꢀCH), 8.12 (d, 1H, J=8.8 Hz, Har), 8.01–7.93 (m,
3
2H, Har), 7.90–7.86 (m, 1H, Har), 7.67 (d, 1H, J=9.0
Hz, Har), 7.55–7.45 (m, 1H, Har), 7.40–7.18 (m, 7H,
Har), 7.05–7.01 (m, 1H, Har), 6.84–6.74 (m, 2H, Har),
4.94 (s, 1H, OH); IR (KBr): 3333m br, 3057w, 1611s,
1505s, 1433m, 1346s, 1278s, 1203s, 1149s, 978m, 815s,
752s cm−1; MS (EI, 70 eV): m/z 389.1 (38, M+), 372.2
(60, M+−OH), 268.2 (100, M+−C6H7NO).
3
1H, J=8.8 Hz, Har), 7.90–7.87 (m, 1H, Har), 7.84 (d,
3
1H, J=8.8 Hz, Har), 7.83–7.79 (m, 1H, Har), 7.39 (d,
3
1H, J=8.7 Hz, Har), 7.37–7.32 (m, 1H, Har), 7.30–7.21
3.3.2. (S)-2-(2-Hydroxybenzylideneamino)-2%-methoxy-
1,1%-binaphthyl (S)-7. Recrystallisation from ethanol
yielded (S)-7 as a yellow powder (1.9 g, 80%). Mp
178–180°C; [h]2D1=+40 (c 1.03, benzene). Anal. calcd for
C28H21NO2 (403.5): C, 83.35; H, 5.25; N, 3.47. Found:
C, 83.03; H, 5.30; N, 3.50%; 1H NMR (250 MHz,
C6D6): l 12.74 (s, 1H, OH), 8.24 (s, 1H, NꢀCH),
(m, 3H, Har), 7.20–7.16 (m, 1H, Har), 7.12 (d, 1H,
3J=8.8 Hz, Har), 7.07–7.03 (m, 1H, Har), 4.89 (s, 1H,
OH), 3.49 (s, 2H, NH2); IR (KBr): 3403m, 3328m,
3199m br, 1620s, 1595s, 1512s, 1381s, 1218s, 1176s,
1145s, 822s, 751s, 661m cm−1; MS (EI, 70 eV): m/z
285.2 (100, M+).
3
7.86–7.65 (m, 4H, Har), 7.53 (d, 1H, J=8.3 Hz, Har),
3
7.32 (d, 1H, J=8.7 Hz, Har), 7.25–6.97 (m, 6H, Har),
3.2. (S)-2-(N,N-Dimethylamino)-2%-methoxy-1,1%-binaph-
thyl (S)-4
6.90–6.73 (m, 3H, Har), 6.56–6.46 (m, 1H, Har), 3.29 (s,
3H, OCH3); IR (KBr): 3055w, 2839w, 1613s, 1569s,
1504s, 1462s, 1268s, 1253s, 1188m, 1149s, 1085s, 1054s,
1022m, 967m, 903m, 808s, 751s, 681m, 531m cm−1; MS
(EI, 70 eV) m/z 403.1 (100, M+).
To a stirred solution of 20% aqueous H2SO4 (3.4 mL)
and 35% formaldehyde (3.4 mL) in THF (10 mL) at
0°C was added a suspension of (S)-2 (1 g, 3.3 mmol)
and NaBH4 (0.9 g, 23.8 mmol) in THF (50 mL) over 10
min. After a further 10 min the mixture was poured
into 2% aqueous KOH (300 mL). The remaining sus-
pension was extracted with ethyl acetate (3×100 mL).
The organic phase was dried with MgSO4 and evapo-
rated. The residue was dissolved in benzene/ethanol
(1:1, 100 mL). After half of the solvent was evaporated,
a fine precipitate formed. Cooling to 5°C for 10 h gave
(S)-4 as a white solid (930 mg, 85%). Mp 191°C;
[h]2D1=−154 (c 0.88, benzene). Anal. calcd for
C23H21NO (327.4): C, 84.37; H, 6.46; N, 4.27. Found:
C, 84.09; H, 6.52; N, 4.16%; 1H NMR (250 MHz,
3.3.3.
(S)-2-(2-Pyridinylmethyleneamino)-2%-hydroxy-
1,1%-binaphthyl (S)-86. Recrystallisation from toluene
gave (S)-8 as a fine yellow powder (1.2 g, 65%). Mp
179–181°C; [h]2D1=+275.5 (c 1.12, benzene). Anal. calcd
for C26H18N2O (374.4): C, 83.40; H, 4.85; N, 7.48.
1
Found: C, 82.95; H, 4.92; N, 7.40%; H NMR (250
MHz, CDCl3): l 8.53 (s, 1H, NꢀCH), 8.45 (ddd, 1H,
4
5
3J=4.8 Hz, J=1.7 Hz, J=1.0 Hz, py-H6), 8.05–7.77
(m, 4H, Har), 7.65–6.98 (m, 11H, Har), 6.21 (s, 1H,
OH); IR (KBr): 3333m br, 3057w, 1611s, 1571m, 1505s,
1433m, 1346s, 1278s, 1203m, 1149m, 978m, 815s, 752s,
633m cm−1; MS (EI, 70 eV): m/z 374.1 (40, M+), 357.2
(88, M+−OH), 268.2 (100, M+−C6H6N2).
3
CDCl3): l 7.98 (d, 1H, J=9.1 Hz, Har), 7.92 (d, 1H,
3J=8.7 Hz, Har), 7.88–7.82 (m, 2H, Har), 7.53 (d, 1H,
3
3J=9.1 Hz, Har), 7.47 (d, 1H, J=9.1 Hz, Har), 7.39–
3.3.4.
(S)-2-(2-Pyridinylmethyleneamino)-2%-methoxy-
7.06 (m, 6H, Har), 3.81 (s, 3H, OCH3), 2.55 (s, 6H,
N(CH3)2); IR (KBr): 3060w, 2948w, 2860w, 2827w,
2784w, 1619m, 1592m, 1504s, 1462s, 1264s, 1254s,
1085s, 1054m, 981s, 809s, 753s cm−1; MS (EI, 70 eV)
m/z 327.2 (100, M+).
1,1%-binaphthyl (S)-9. Bulb-to-bulb distillation at 165°C
(0.005 torr) yielded (S)-9 as a yellow glass (1.2 g, 62%).
Mp 78–82°C; [h]2D1=−224 (c 1.10, benzene). Anal. calcd
for C27H20N2O (388.5): C, 83.48; H, 5.19; N, 7.21.
1
Found: C, 83.25; H, 5.36; N, 7.01%; H NMR (250
4
MHz, C6D6): l 8.86 (d, 1H, J=0.5 Hz, NꢀCH), 8.32
3
4
5
3.3. General procedure for the Schiff bases (S)-6, (S)-
7, (S)-8, (S)-9 and (S)-10
(ddd, 1H, J=4.8 Hz, J=1.8 Hz, J=1.0 Hz, py-H6),
7.79–7.42 (m, 7H, Har), 7.33–6.96 (m, 6H, Har), 6.71–
6.61 (m, 1H, py-H4), 6.41 (ddd, 1H, 3J=7.5 Hz, 4J=4.8
5
(S)-2 or (S)-3 (5 mmol) and MgSO4 (400 mg) were
suspended in benzene (30 mL). After adding the desired
aldehyde (5.5 mmol) the suspension was stirred for 20
h. The yellow–orange mixture was filtered and the
solvent and excess aldehyde were evaporated by gentle
Hz, J=1.3 Hz, py-H5), 3.22 (s, 3H, OCH3); IR (KBr):
3055m, 3006w, 2937w, 2838w, 1620s, 1590s, 1506s,
1467s, 1433m, 1334m, 1264s, 1254s, 1211m, 1148m,
1085s, 1054s, 813s, 748s, 682m, 617m cm−1; MS (EI, 70
eV): m/z 388.1 (100, M+), 357.2 (52, M+−OCH3).

42
H. Brunner et al. / Tetrahedron: Asymmetry 13 (2002) 37–42
3.3.5. (S)-2-(2-Diphenylphosphanylbenzylideneamino)-2%-
methoxy-1,1%-binaphthyl (S)-10. Recrystallisation from
methanol (400 mL) yielded (S)-10 as a fine yellow
powder (1.8 g, 64%). Mp 146–148°C; [h]2D1=−177 (c
1.01, benzene). Anal. calcd for C40H30NOP (571.7): C,
84.04; H, 5.29; N, 2.45. Found: C, 83.36; H, 5.30; N,
References
1. (a) Smrcˇina, M.; Lorenc, M.; Hanusˇ, V.; Kocˇovsky´, P.
Synlett 1991, 231–232; (b) Smrcˇina, M.; Lorenc, M.;
Hanusˇ, V.; Sedmera, P.; Kocˇovsky´, P. J. Org. Chem.
&
1992, 57, 1917–1920; (c) Vyskocˇil, S.; Smrcˇina, M.;
Lorenc, M.; Hanusˇ, V.; Pola´sˇek, M.; Kocˇovsky´, P.
Chem. Commun. 1998, 585–586.
1
2.21%; H{31P} NMR (400 MHz, C6D6): l 9.46 (s, 1H,
NꢀCH), 7.82–7.61 (m, 6H, Har), 7.52–7.40 (m, 2H, Har),
7.32–6.88 (m, 16H, Har), 6.79–6.69 (m, 2H, Har), 3.21
(s, 3H, OCH3); 31P NMR (162 MHz, C6D6): l −14.39;
IR (KBr): 3054w, 2838w, 1618s, 1591s, 1507s, 1461s,
1432s, 1641m, 1265s, 1148m, 1085s, 1054s, 1023m,
967m, 808s, 746s, 695s, 516m, 498s, 471s, 436m cm−1;
MS (EI, 70 eV): m/z 571.1 (8, M+), 556.1 (8, M+−CH3);
540.0 (100, M+−OCH3), 494.1 (22, M+−C6H5).
2. (a) Ding, K.; Xu, Q.; Wang, Y.; Jinxia, L.; Yu, Z.; Du,
B.; Wu, Y.; Koshima, H.; Matsuura, T. Chem. Commun.
1997, 693–694; (b) Ding, K.; Wang, Y.; Yun, H.; Liu,
J.; Wu, J.; Terada, M.; Okubo, Y.; Mikami, K. Chem.
Eur. J. 1999, 5, 1734–1737; (c) Mahmoud, H.; Han, Y.;
Segal, B. M.; Cai, L. Tetrahedron: Asymmetry 1998, 9,
2035–2042.
3. (a) Hattori, T.; Hotta, H.; Suzuki, T.; Miyano, S. Bull.
Chem. Soc. Jpn. 1993, 66, 613–622; (b) Hattori, T.;
Shijo, M.; Sakamoto, J.; Kumagai, S.; Nakajima, A.;
Miyano, S. J. Chem. Res. (M) 1995, 124–134.
3.4. (S)-2-(2-Pyridinylmethylamino)-2%-hydroxy-1,1%-
binaphthyl (S)-11
(S)-8 (0.6 g, 1.6 mmol) was dissolved in methanol (50
mL) and NaBH4 (73 mg, 1.9 mmol) was added with
stirring at room temperature. The yellow colour disap-
peared and after 2 h diethyl ether (100 mL) and water
(100 mL) were added. The aqueous layer was extracted
further with diethyl ether (2×50 mL). The combined
organic layers were dried with Na2SO4 and evaporated.
Purification by silica gel column chromatography with
petroleum ether (40/60) and ethyl acetate (1:1) gave
(S)-11 as a white solid (364 mg, 60%). Mp 138–140°C;
[h]2D1=−155 (c 0.99, benzene). Anal. calcd for
C26H20N2O (376.5): C, 82.95; H, 5.35; N, 7.44. Found:
C, 82.31; H, 5.35; N, 7.39%; 1H NMR (400 MHz,
&
4. Smrcˇina, M.; Vyskocˇil, S.; Pol´ıvkova´, J.; Sejbal, J.;
Hanusˇ, V.; Pola´sˇek, M.; Verrier, H.; Kocˇovsky´, P. Tet-
rahedron: Asymmetry 1997, 8, 537–546.
5. Mahmoud, H.; Han, Y.; Segal, B. M.; Cai, L. Tetra-
hedron: Asymmetry 1998, 9, 2035–2042.
6. Zhang, X. Patent 1/4/2001, WO 0,100,581.
7. Hashiguchi, S.; Fuji, A.; Takehara, J.; Ikariya,
T.; Noyori, R. J. Am. Chem. Soc. 1995, 117, 7562–
7563.
8. Nordin, S. J. M.; Roth, P.; Tarnai, T.; Alonso, D. A.;
Brandt, P.; Andersson, P. G. Chem. Eur. J. 2001, 7,
1431–1436.
9. Vedejs, E.; Trapencieris, P.; Suna, E. J. Org. Chem.
1999, 64, 6724–6729.
10. Meuzelaar, G. J.; van Vliet, M. C. A.; Maat, L.; Shel-
don, R. A. Eur. J. Org. Chem. 1999, 2315–2321.
11. Samano, V.; Ray, J. A.; Thompson, J. B.; Mook, R. A.;
Jung, D. K.; Koble, C. S.; Martin, M. T.; Bigham, E.
C.; Regitz, C. S.; Feldman, P. L.; Boros, E. E. Org.
Lett. 1999, 1, 1993–1996.
12. Noyori, R.; Hashiguchi, S. Acc. Chem. Res. 1997, 30,
97–102.
13. Yamakawa, M.; Ito, H.; Noyori, R. J. Am. Chem. Soc.
2000, 122, 1466–1478.
3
4
CDCl3/D2O): l 8.40 (ddd, 1H, J=4.9 Hz, J=1.7 Hz,
5J=0.9 Hz, py-H6), 7.95 (d, 1H, 3J=8.9 Hz, Har),
7.91–7.87 (m, 1H, Har), 7.79–7.71 (m, 2H, Har), 7.58
3
3
4
(ddd, 1H, J=7.5 Hz, J=7.7 Hz, J=1.5 Hz, py-H5),
3
7.42 (d, 1H, J=9.1 Hz, Har), 7.38–7.32 (m, 1H, Har),
7.46–6.94 (m, 8H, Har), 4.76 (s, 1H, NH), 4.67 (d, 1H,
3J=16.9 Hz, NCHA), 4.49 (d, 1H, 3J=17.0 Hz,
NCHB); IR (KBr): 3494w, 3418m, 3056m, 1618s, 1597s,
1510s, 1430s, 1377m, 1341s, 1310s, 1274m, 1217s,
1179m, 1148s, 974m, 813s, 753s, 621m, 428m cm−1; MS
(EI, 70 eV): m/z 376.4 (100, M+), 358.4 (40, M+−H2O);
280.3 (34, M+−C5H4N), 268.3 (45, M+−C6H8N2).