Synthesis of bis(binol) substituted 2,2′-bipyridines and their late transition metal complexes

Article abstract of DOI:10.1055/s-2002-34948

Bis(BINOL) substituted 2,2′-bipyridines (1a and 1b) have been prepared via a twofold Sonogashira cross-coupling reaction from 3-iodo-2,2′-di(methoxymethoxy)-1,1′-binaphthyl (4) and 5,5′-diethynyl-2,2′-bipyridine (2), which could be synthesised through a palladium mediated homodimerisation using zinc powder as a reducing agent. 1a and 1b form well defined silver(I), copper(I) or zinc(II) complexes [M1₂]⁺and [Zn1a₂]²⁺ thereby orienting the BINOL groups in a fashion potentially useful for molecular recognition of chiral substrates.

Full text of DOI:10.1055/s-2002-34948

PAPER
2289
Synthesis of Bis(BINOL) Substituted 2,2 -Bipyridines and their Late
Transition Metal Complexes
B
A
is(BINOL) Subst
r
ituted 2,
n2 -Bipyridines Lützen,* Marko Hapke, Sven Meyer
University of Oldenburg, Department of Chemistry, P. O. Box 2503, 26111 Oldenburg, Germany
E-mail: arne.luetzen@uni-oldenburg.de
Received 28 June 2002; revised 19 July 2002
standing performance in not only asymmetric catalysis
but also as receptors could often even be increased
Abstract: Bis(BINOL) substituted 2,2 -bipyridines (1a and 1b)
have been prepared via a twofold Sonogashira cross-coupling reac-
tion from 3-iodo-2,2 -di(methoxymethoxy)-1,1 -binaphthyl (4) and
through the use of compounds containing multiple
4
5
,5 -diethynyl-2,2 -bipyridine (2), which could be synthesised BINOL units. Recently, we were able to synthesise an
through a palladium mediated homodimerisation using zinc powder example where four BINOL units are covalently linked to
5
as a reducing agent. 1a and 1b form well defined silver(I), copper(I)
a central spirobifluorene. However, the synthesis and iso-
+
2+
or zinc(II) complexes [M1 ] and [Zn1a ] thereby orienting the
2
2
lation of this compound as of some others of these oli-
go(BINOL) compounds proved to be quite tedious
although convergent strategies have been used. Therefore,
we were looking for an alternative way to build up such an
oligo(BINOL) and we decided to make use of self-assem-
BINOL groups in a fashion potentially useful for molecular recog-
nition of chiral substrates.
Key words: cross-coupling reactions, palladium, ligands, com-
plexes, supramolecular chemistry
6
bly processes of metal complexes to build up self-assem-
bled analogues.
2
,2 -Dihydroxy-1,1 -binaphthyl (BINOL) and its deriva-
Herein, we would like to report on our design and synthe-
sis concept based on a homofunctionalised central 2,2 -bi-
pyridine as the central ligand unit for co-ordinating to an
appropriate transition metal ion which is linked to two
BINOLs via ethynyl bridges (Figure 1).7
tives certainly belong to the most important components
of catalysts that are routinely used in asymmetric
synthesis and they have also been used very successfully
1
in the recognition of chiral substrates both in solid phase
and solution phase supramolecular chemistry.2 This out-
,3
n+
R
O
OR
OR
R
O
R
O
O
R
N
Mn+
N
N
M
N
R
O
N
N
M = Cu, Zn, Ag
O
R
R
RO
RO
O
O
R
1
1
a = MOM
b = H
[
M12]n+
Figure 1 Bis(BINOL) substituted 2,2 -bipyridine (1) and its dimeric metal complex.
Synthesis 2002, No. 15, Print: 29 10 2002.
Art Id.1437-210X,E;2002,0,15,2289,2295,ftx,en;Z09902SS.pdf.
©
Georg Thieme Verlag Stuttgart · New York
ISSN 0039-7881

2
290
A. Lützen et al.
PAPER
The central 5,5 -diethynyl-2,2 -bipyridine (2) core has al-
ready been prepared earlier by Ziessel and co-workers.8
However, the initial bromination of 2,2 -bipyridine to the
mono- and the dibrominated product needs relatively
harsh conditions and some further problems with this pro-
HIO4·2 H2O, I2,
CH3COOH, H2O,
conc. H2SO4
I
N
NH2
N
NH2
68 %
9
,10
cedure have been reported. As an alternative to this di-
rect functionalisation of 2,2 -bipyridines cross- and
homocoupling reactions have been employed. Only re-
cently, e.g., Michl et al. described a synthesis of the dibro-
NaNO2, conc. HCl, -5 °C,
-5 °C - rt, then 70 °C
4
2 %
TMS
1
0
minated compound based on a Stille reaction. During
our efforts in developing a new approach to monofunc-
tionalised 5-substituted 2,2 -bipyridines through a modi-
Pd(PPh3)2Cl2, CuI,
Et3N, HCCSiMe3,
rt, 48 h
I
1
1
N
fied Negishi cross-coupling reaction we thought to use a
palladium mediated reaction also for the homodimerisa-
tion of 2-chloropyridines with zinc powder as a reducing
agent. Hence, 5,5 -bis[(trimethylsilyl)ethynyl]-2,2 -bipy-
ridine (3) was prepared in a four step synthesis starting
76 %
N
Cl
Cl
Pd(OAc)2, t-Bu2(2-biph)P,
Zn, DMF, 50 °C
62 %
from
commercially
available
2-aminopyridine
(
Scheme 1). The first steps were conducted following
1
2
published procedures. Initial electrophilic iodination
N
1
3
and subsequent Sandmeyer analogous reaction was fol-
lowed by a first palladium catalysed Sonogashira cou-
pling with trimethylsilylacetylene to give 2-chloro-5-
[
2
TMS
TMS
N
3
1
4
(trimethylsilyl)ethynyl]-pyridine in an overall yield of
2%. The homodimerisation of this compound in a one-
79 %
KF, MeOH, rt
pot-synthesis could be accomplished using palladium(II)
acetate, Buchwald’s ligand 2-(di-tert-butylphospha-
1
5
N
nyl)biphenyl [t-Bu (2-biph)P], and zinc powder in DMF
2
1
6
at 50-60 °C. The product 3 could be isolated in 62%
yield. Finally, pure 2 was obtained after complete desily-8
lation with potassium fluoride in methanol in 79% yield.
N
2
Scheme 1
It should be noted that the often used nickel mediated ho-
1
7
modimerisation procedures could not be used in this case
because the ethynyl groups were not tolerated by this met-
al under our conditions. Although there are existing pro-
NaH, DMF/THF, 0 °C
rt, MOMCl
cedures using palladium as
electrochemical or chemical method of reduction
a
catalyst and an
1
7a,18
OH
OH
OMOM
OMOM
our
approach seems to be an efficient and mild method for
performing homocoupling reactions. Thus, further studies
concerning the scope and limitations of this catalytic sys-
tem are currently underway.
80 %
a) 1.15 equiv n-BuLi,
.20 equiv TMEDA
THF, -78 °C - rt
Enantiopure
(S )-
and
(R )-3-iodo-2,2 -di(meth-
a
a
1
oxymethoxy)-1,1 -binaphthyl (4) were prepared in two
b) 1.2 equiv I2, THF,
steps from enantiopure BINOL as shown in
-78 °C
5
,19,20
Scheme 2.
After standard methoxymethyl ether pro-
tection of the hydroxyl functions in 80% yield, ortho-lithi-
ation facilitated by the protecting groups followed by
quenching with iodine furnished the desired monoiodinat-
ed BINOL 4 together with diiodinated BINOL derivative
I
OMOM
OMOM
OMOM
OMOM
+
5
which could be separated by column chromatography on
silica gel. It should be mentioned that we were able to shift
the ratio of the products in favour of the monoiodinated
compound compared to our earlier results through the ad-
I
I
4: 55 %
5: 35 %
dition of N,N,N ,N -tetramethylethylendiamine (TME- Scheme 2
DA), however, 5 is also a versatile building block for the
5
,21
synthesis of interesting BINOL-derivatives.
Synthesis 2002, No. 15, 2289–2295 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Bis(BINOL) Substituted 2,2 -Bipyridines
2291
Finally, twofold Sonogashira cross-coupling reaction of 2 resulted in instant colour changes to intensive red-brown
and 4 using tris(dibenzylideneacetone)dipalladium(0) in case of the copper(I) salt and intensive yellow in case
2
2
(
Pd dba CHCl ),
1,1 -bis(diphenylphosphanyl)-ferro- of the silver(I) and zinc(II) salt, indicating the formation
2
3
3
2
3
cene (dppf), and copper(I) iodide as catalytic system of metal complexes.
gave tetra-MOM protected bis(BINOL) substituted 2,2 -
This was confirmed by NMR experiments of solutions in
bipyridine 1a in excellent yield of 96% and the corre-
sponding tetrol 1b was obtained in almost quantitative
yield after acidic hydrolysis as depicted in Scheme 3.
1
deuterated solvents where significant shifts in the H and
13
C NMR spectra were observed (Figure 2). Copper(I)
complexes show essentially the same spectroscopic be-
haviour as the silver(I) complexes.
N
OMOM
2
+
OMOM
N
I
4
2
Pd2dba3·CHCl3, dppf,
CuI, Et3N, 45-50 °C
96 %
OR
OR
N
N
RO
RO
1
a = MOM
b = H
conc. HCl, MeOH/THF
7 %
9
1
1
1
Figure 2 H NMR spectra (500.1 MHz, [1a] = 8 11 mmolL in
0
Scheme 3
CD Cl CD CN at 300 K) (a) (all-S )-1a (b) (all-S )-1a + 0.5 equiv
2
2
3
a
a
[
Ag(CH CN) ]BF (c) (all-S )-1a + 0.5 equiv Zn(ClO ) 6 H O.
3 4 4 a 4 2 2
Addition of previously prepared or commercially avail-
able Zn(BF ) 6 7 H O, Zn(ClO ) 6 H O, AgClO , These complexes could also be characterised by ESI-MS
4
2
2
4 2
2
4
[
(
Ag(CH CN) ]BF , or [Cu(CH CN) ]BF to solutions of where we only found signals with the expected isotope
3 2 4 3 4 4
all-S )-1a or (all-R )-1a in dichloromethane–acetonitrile patterns arising from the desired complexes and their frag-
a
a
Figure 3 Positive ESI-MS of a 5 10 4 mol L 1 soln of [Zn(all-S )-1a ](BF ) complex in CH Cl CH CN.
a
2
4 2
2
2
3
Synthesis 2002, No. 15, 2289–2295 ISSN 0039-7881 © Thieme Stuttgart · New York

2
292
A. Lützen et al.
PAPER
mentation products, respectively, as shown for the zinc be suitable compounds for recognition studies on chiral
complex in Figure 3.
substrates.
We were also able to prepare metal complexes with the
deprotected ligand 1b. The formation of coloured metal
complexes could again be observed by significant shifts in
1
13
the H and the C NMR spectra as well as by ESI-MS.
The zinc(II) metal ions showed an interesting behaviour.
Whereas zinc(II) ions and 1a form exclusively well de-
2
+
fined [Zn1a ] complexes, a different behaviour was
2
found for ligand 1b. When we mixed zinc(II) ions and 1b
in a 1:2 ratio we observed the formation of two different
2
+
metal complexes, most probably a mixture of a [Zn1b ]
2
2
+
and a [Zn1b3] complex, as indicated by respective sig-
nals in the ESI-MS. The latter coordination complex
seems now possible because of less steric repulsion due to
the lack of the MOM groups compared to 1a. However,
1
most of the H NMR signals were very broad when we re-
corded spectra at room temperature indicating that these
complexes are in a fast equilibrium. This could, however,
be considerably slowed down by lowering the tempera-
ture to 0 °C where sharp signals were observed. Both spe-
cies, although in slightly different ratio, were still present
in a mixture together with free ligand when we increased
the amount of 1b to a sixfold excess. Although this is a
very nice example for the tremendous effects of small
structural changes on self-assembly processes in su-
pramolecular chemistry we did not investigate this phe-
nomenon any further because a fast equilibrating system
like this would not be effective or at least very difficult to
rationalise in the sense of an application of these complex-
es in catalysis or molecular recognition.
1
Figure 4 H NMR spectra (500.1 MHz, [1b] = ca. 10 mmolL in
0
THF-d8 CD CN at 300 K) (a) (all-S )-1b (b) (all-S )-1b + 0.5 equiv
3
a
a
[
Ag(CH CN) ]BF (c) (all-S )-1b + 0.5 equiv [Cu(CH CN) ]BF .
3 2 4 a 3 4 4
In conclusion, we have presented the synthesis and self-
assembly behaviour of bis(BINOL) substituted 2,2 -bipy-
ridines 1. These form well defined dimeric complexes
upon coordination to silver(I) or copper(I) ions. This is
also true for the zinc(II) complex of the fully MOM-pro-
tected ligand 1a. Unprotected tetrol 1b was found to be-
have differently when coordinated to zinc(II) ions because
in this case a fast equilibrium of dimeric and trimeric
+
2+
[
Zn1b2]2 and [Zn1b3] complexes was observed. The
dimeric complexes give rise to supramolecular structures
that closely reassemble a covalently linked tetra(BINOL)
substituted spirobifluorene derivative. We are currently
However, silver(I) and copper(I) ions again formed well
+
defined [M1b ] complexes (Figures 4 and 5) which may
2
Figure 5 Positive ESI-MS of a ca. 5 10 4 mol L 1 soln of [Ag(all-S )-1b ]BF complex in CH Cl CH CN.
a
2
4
2
2
3
Synthesis 2002, No. 15, 2289–2295 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Bis(BINOL) Substituted 2,2 -Bipyridines
2293
investigating the recognition behaviour of both species in 1H NMR and 13C NMR spectroscopic data recorded in CDCl
the binding of chiral substrates like monosaccharides.
were
3
8
in agreement with the ones reported by Ziessel.
3
-Iodo-2,2 -di(methoxymethoxy)-1,1 -binaphthyl (4)5
2
-Aminopyridine was purchased from Sigma-Aldrich Chemie
A soln of 2,2 -di(methoxymethoxy)-1,1 -binaphthyl (1 g, 2.67
mmol) in anhyd THF (10 mL) was cooled to -78 °C, treated with
TMEDA (0.48 mL, 3.21 mmol) and subsequently with n-BuLi (2.2
GmbH and used as received. Trimethylsilylacetylene was a gener-
ous gift from Wacker-Chemie GmbH. THF was dried over and dis-
tilled from sodium benzophenone ketyl. DMF and Et N were dried
–
1
3
mL of a 1.38 molL soln in hexane, 3.02 mmol). The soln was al-
lowed to warm up to 0 °C and stirred at that temperature for 30 min.
After cooling to –78 °C again iodine (805 mg, 3.18 mmol) dissolved
in anhyd THF (10 mL) was added dropwise. After stirring for an-
other 30 min the mixture was allowed to warm up to r.t., quenched
with 10% aq sodium dithionite soln (20 mL), and extracted with
EtOAc (3 30 mL). The combined organic layers were washed with
H O and brine and dried over Na SO . After removing the solvents
over calcium hydride. Tris(dibenzylideneacetone)dipalladium(0)
21
(
Pd dba CHCl ), 1,1 -bis(diphenylphosphanyl)-ferrocene (dp-
2
2
3
3
2
15
pf), and t-Bu (2-biph)P were prepared following published pro-
cedures. n-BuLi solutions were purchased from Merck and were
titrated prior to use against N-pivaloyl-o-toluidine. Sensitive reac-
tions were performed under an argon atmosphere in oven-dried
glassware using standard Schlenk techniques.
2
2
4
2
2
4
the residue was subjected to column chromatography on silica gel
Thin-layer chromatography was performed on aluminum TLC-lay-
ers Silica gel 60 F254 from Merck. Detection was done by UV-light
using PE–EtOAc (5:1 containing 0.5% of Et N) as eluent to give the
3
desired product together with the diiodinated BINOL 5.
(
254 and 366 nm). Products were purified by column chromatogra-
1
phy on silica gel (0.063–0.2 or 0.004–0.063 mm) from Merck. H
White solid; yield: 700 mg (52%) together with 580 mg (32%) 3,3 -
diiodo-2,2 -di(methoxymethoxy)-1,1 -binaphthyl; mp 114 °C.
and 13C NMR spectra were recorded on a Bruker DRX 500 spec-
1
trometer at 500.1 and 125.8 MHz, respectively. H NMR chemical
shifts are reported on the -scale (ppm) relative to residual nondeu-
(R )-4
a
1
3
20
terated solvent as internal standard. C NMR chemical shifts are re-
ported on the -scale relative to deuterated solvent as internal
[ ]D +99.5 (c = 0.99, THF).
1
13
standard. Signals were assigned on the basis of H, C, H,H-COSY,
HMQC, and (in some cases) HMBC NMR experiments. Mass spec-
tra were taken on a Finnegan-MAT 212 instrument with data system
MMS and processing system ISIS or on a Finnigan MAT 95 with
data system DEC-Station 5000 in CI mode with i-butane as reactant
gas. ESI-MS measurements were conducted with a Thermoquest
Finnigan LCQ with processing software Xcalibur. Melting points
were measured with a hot-stage microscope SM-Lux from Leitz and
are not corrected. Elemental analyses were carried out with a EA
(S )-4
a
2
0
[ ]D –100.1 (c = 0.99, THF).
1H NMR and 13C NMR spectroscopical data recorded in CDCl
have been previously reported.
3
5,21b
(
all-S )-5,5 -Di[2,2 -di(methoxymethoxy)-3-ethyndiyl-1,1 -bi-
a
naphthyl]-2,2 -bipyridine (1a)
Sa)-3-Iodo-2,2 -di(methoxymethoxy)-1,1 -binaphthyl (4) (541 mg,
.08 mmol), 5,5 -diethynyl-2,2 -bipyridine (2) (96 mg, 0.47 mmol),
Pd dba CHCl (7.4 mg, 3 mol% Pd), dppf (7.9 mg, 3 mol%), and
(
1
1
108 Fisons Instruments. Specific optical rotations were measured
2
3
3
on a Perkin Elmer Polarimeter 343 in a 10 cm cuvette. Petroleum
copper(I) iodide (5.4 mg, 6 mol%) were evacuated and flushed with
argon two times in a Schlenk flask. Anhyd Et N (35 mL) was added
ether (PE) used had a bp range of 40 60 °C. All washing and ex-
2
5
3
traction steps were performed according to standard procedures.
and the mixture heated to 45–50 °C. After some time a bright beige
precipitate formed and after 24 h the reaction was completed. After
cooling to r.t., the mixture was diluted with brine (10 mL) and
CH Cl (40 mL). After stirring for a short period of time the solids
5
,5 -Bis[(trimethylsilyl)ethynyl]-2,2 -bipyridine (3)8
In a Schlenk flask Pd(OAc) (81 mg, 0.36 mmol), t-Bu (2-biph)P
2
2
2
2
(
(
215 mg, 0.72 mmol), 2-chloro-5-[(trimethylsilyl)ethynyl]-pyridine
1.5 g, 7.2 mmol), and zinc powder (804 mg, 12.3 mmol) were twice
were removed by filtration over celite. The precipitate was washed
with CH Cl . The filtrate was extracted several times with CH Cl
and the combined organic layers were washed with sat. aq NaHCO3
soln and dried over Na SO . Evaporation of the solvents and two-
fold column chromatography on silica using PE–EtOAc (2:1 con-
taining 5% Et N) as eluent gave the pure product.
2
2
2
2
evacuated and flushed with argon. Anhyd DMF (20 mL) was added
and the mixture heated to 50–55 °C. After TLC indicated the com-
plete consumption of 2-chloro-5-[(trimethylsilyl)ethynyl]-pyridine,
the mixture was cooled to r.t. A suspension of EDTA (10 g, 34
2
4
3
mmol) in H O (100 mL) was added and the mixture stirred for 15–
2
Yellow solid; yield 430 mg (96%); mp 210–212 °C.
3
0 min. Neutralisation with sat. aq Na CO soln to pH 8–9 was fol-
2 3
lowed by extraction with CH Cl . The combined organic layers
2
2
(
[
all-S )-1a
a
]D –204.5 (c = 1.0, THF).
were dried over Na SO and the solvent removed in vacuo. The res-
2
4
2
0
idue was subjected to column chromatography on silica using PE
EtOAc Et N (75:25:0.5) as eluent. The product was dried in high
vacuum and used for the desilylation procedure.
3
(
[
1
all-R )-1a
]D +191.4 (c = 0.93, THF).
a
2
0
Slightly brownish-yellow solid; yield: 780 mg (62%).
H NMR (CD Cl –CD CN 6:1): = 2.79 (s, 6 H), 3.23 (s, 6 H), 4.93
1H NMR and 13C NMR spectroscopical data recorded in CDCl
2
2
3
3
(
d, 2 H, J = –5.8 Hz), 5.02 (d, 2 H, J = –5.8 Hz), 5.09 (d, 2 H, J =
6.9 Hz), 5.19 (d, 2 H, J = –6.9 Hz), 7.15–7.21 (m, 4 H), 7.29-7.35
m, 4 H), 7.41 (ddd, 2 H, J = 7.3, 7.3, 0.9 Hz), 7.48 (ddd, 2 H,
J = 7.3, 7.3, 0.9 Hz), 7.65 (d, 2 H, J = 9.2 Hz), 7.92–7.98 (m, 4 H),
.03 (dd, 2 H, J = 8.3, 2.2 Hz), 8.05 (d, 2 H, J = 9.2 Hz), 8.32 (s, 2
H), 8.51 (d, 2 H, J = 8.3 Hz), 8.89 (d, 2 H, J = 2.2 Hz).
were in agreement with the ones reported by Ziessel.8
–
(
5
,5 -Diethynyl-2,2 -bipyridine (2)8
Compound 3 (740 mg, 2.12 mg) and potassium fluoride (738 mg,
2.7 mmol) were dissolved in MeOH (200 mL) and stirred for 15 h
8
1
8
according to the procedure published by Ziessel et al. The solvent
was evaporated and the residue subjected to column chromatogra-
1
3
C NMR (CD Cl –CD CN, 6:1): = 55.7, 56.2, 90.2, 91.0, 95.0,
2
2
3
9
1
1
8.9, 116.3, 116.9, 119.6, 120.4, 120.5, 124.1, 125.2, 125.6, 125.8,
26.4, 126.5, 127.4, 127.9, 127.9, 129.6, 129.9, 130.4, 133.8, 134.0,
34.1, 139.2, 151.6, 152.5, 153.0, 154.2.
phy on silica using PE–EtOAc–Et N (75:25:0.5) as eluent.
Reddish solid; yield: 342 mg (79%); mp 130 °C (decomp.) (Lit.8
3
1
30 °C).
ESI-MS: m/z (%) = 949.4 (100) (MH+).
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2
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A. Lützen et al.
PAPER
Anal. Calcd for C H N O THF: C, 77.63; H, 5.53; N, 2.74.
Zinc(II) Complex of 1a [Zn1a (ClO ) ]
62
48
2
8
2
4 2
Found: C, 77.78; H, 5.59; N, 2.83.
The zinc(II) complex was prepared following the same procedure as
described for [Ag1a ]BF .
2
4
(
2
all-S )-5,5 -Di[3-ethyndiyl-2,2 -di(hydroxyl)-1,1 -binaphthyl]-
,2 -bipyridine (1b)
a
Solid; mp >180 °C (dec.).
(
all-S )-5,5 -Di(2,2 -di(methoxymethoxy)-3-ethyndiyl-1,1 -binaph-
a
(
[
all-R )-1a
a
thyl)-2,2 -bipyridine 1a (100 mg, 0.105 mmol) was dissolved in a
mixture of MeOH (50 mL) and THF (50 mL). Concd HCl (37%, 2
mL) was added and the reaction mixture stirred for 20 h. After that
time a small amount of H O was added and the organic solvents
were removed. The precipitate formed was filtered off, thoroughly
20
]D +426.4 (c = 0.31, THF CH CN, 9:1).
3
(
[
1
all-S )-1a
a
20
2
]D –418.2 (c = 0.30, THF CH CN, 9:1).
3
H NMR (CD Cl CD CN, 6:1): = 2.68 (s, 12 H), 3.11 (s, 12 H),
washed with H O and small amounts of cold MeOH, and dried in
high vacuum.
2
2
3
2
4
.77 (d, 4 H, J = –4.9 Hz), 4.86 (d, 4 H, J = –4.9 Hz), 4.99 (d, 4 H,
J = –6.9 Hz), 5.09 (d, 4 H, J = –6.9 Hz), 7.05 (d, 4 H, J = 8.6 Hz),
Intensive yellow solid; yield: 79 mg (97%); mp 208–210 °C.
7
7
7
8
.16 (d, 4 H, J = 8.2 Hz), 7.18–7.21 (m, 4 H), 7.28–7.32 (m, 4 H),
.29–7.34 (m, 4 H), 7.39–7.43 (m, 4 H), 7.57 (d, 4 H, J = 9.2 Hz),
.84–7.88 (m, 8 H), 7.98 (d, 4 H, J = 9.2 Hz), 8.26 (s, 4 H), 8.31–
.35 (m, 4 H), 8.40-8.46 (m, 4 H), 8.59-8.65 (m, 4 H).
(
[
all-S )-1b
a
20
]D –304.6 (c = 0.91, THF).
1
3
C NMR (CD Cl CD CN, 6:1): = 55.9, 56.5, 88.1, 95.2, 95.3,
(
[
all-R )-1b
]D +310.7 (c = 0.85, THF).
2
2
3
a
20
99.3, 116.1, 116.5, 119.4, 123.2, 124.3, 124.4, 125.3, 126.0, 126.1,
1
1
26.8, 126.8, 128.2, 128.2, 128.3, 129.8, 130.3, 130.6, 133.9, 134.6,
35.0, 143.7, 147.1, 150.6, 152.6, 153.2.
1H NMR (THF-d8): = 7.02 (d, 2 H, J = 8.4 Hz), 7.08 (d, 2 H,
J = 8.4 Hz), 7.16–7.20 (m, 4 H), 7.22–7.26 (m, 2 H), 7.26–7.28 (m,
2
(
8
2
+
2+
ESI-MS: m/z (%) = 981.1 (49) [Zn1a ] , 959.3 (100) [Zn1a ]
C H O, 936.7 (79) [Zn1a ]
H), 7.28 (d, 2 H, J = 8.8 Hz), 7.83 (dd, 4 H, J = 2.6, 8.1 Hz), 7.88
d, 2 H, J = 8.8 Hz), 8.03 (dd, 2 H, J = 8.1, 1.8 Hz), 8.20 (s, 2 H),
.54 (d, 2 H, J = 8.1 Hz), 8.84 (d, 2 H, J = 1.8 Hz). Resonances of
2
2
2
+
2 C H O.
2
5
2
2 5
Anal. Calcd for the perchlorate C124H Cl N O Zn 3 H O: C,
67.19; H, 4.64; N, 2.53. Found: C, 67.21; H, 4.64; N, 2.44.
96
2
4
24
2
the free OH protons could only be observed as a broad H O peak.
2
13C NMR (THF-d8): = 91.0, 92.0, 114.0, 114.0, 116.0, 119.6,
Silver(I) Complex of 1b [Ag1b ]BF
The silver(I) complex was prepared following the same procedure
1
1
21.2, 122.0, 123.6, 124.3, 125.3, 125.6, 127.1, 128.7, 128.7, 129.6,
30.1, 130.8, 134.6, 135.5, 135.8, 139.9, 152.4, 154.1, 154.9, 155.0.
2
4
as described for [Ag1a ]BF .
ESI-MS: m/z (%) = 773.3 (100) (MH+).
2
4
Solid, mp >200 °C (dec.).
Anal. Calcd for C H N O 2 MeOH: C, 80.37; H, 4.82; N, 3.35.
54
32
2
4
Found: C, 80.45; H, 4.88; N, 3.44.
(
[
all-S )-1b
a
2
0
]D –523.8 (c = 0.515, THF CH CN, 9:1).
3
Silver(I) Complex of 1a [Ag1a ]BF
2
4
A soln of 1a (15.0 mg, 15.8 mol) in 0.6 mL THF-d was added to
8
(
[
all-R )-1b
a
a soln of Ag(CH CN) BF (2.2 mg, 7.9 mol) in 0.1 mL CD CN.
20
3
2
4
3
]D +534.4 (c = 0.605, THF CH CN, 9:1).
3
The resulting yellow soln was subjected to NMR analysis. The com-
plex could be isolated as solid by removing of the solvents and
washing with MeOH.
1H NMR (THF-d8 CD CN, 7:1): = 6.99 (d, 4 H, J = 8.6 Hz), 7.03
(
(
3
d, 4 H, J = 8.5 Hz), 7.16–7.21 (m, 8 H), 7.23–7.28 (m, 8 H), 7.28
d, 4 H, J = 8.9 Hz), 7.75 (br s, 4 H), 7.81–7.85 (m, 8 H), 7.90 (d, 4
Solid; yield 16.5 mg (quant.); mp >210 °C (dec.).
H J = 8.9 Hz), 7.97 (br s, 4 H), 8.17 (dd, 4 H, J = 8.6, 1.8 Hz), 8.20
s, 4 H), 8.50 (d, 4 H, J = 8.6 Hz), 8.90 (d, 4 H, J = 1.8 Hz).
(
(
[
all-S )-1a
a
13C NMR (THF-d8 CD CN, 7:1): = 90.3, 93.1, 113.5, 113.8,
1
1
20
]D –401.6 (c = 0.5, THF CH CN, 9:1).
3
3
16.3, 119.5, 122.5, 122.9, 123.7, 124.5, 125.1, 125.6, 127.2, 128.3,
28.8, 128.9, 129.5, 130.1, 131.0, 134.8, 135.4, 135.8, 141.1, 152.6,
(
[
1
all-R )-1a
a
20
153.2, 153.7, 154.9.
]D +390.0 (c = 0.50, THF CH CN, 9:1).
3
+
+
ESI-MS: m/z (%) = 1653.0 (100) [Ag1b ] , 881.0 (30) [Ag1b] ,
7
H NMR (CD Cl2 CD CN, 6:1): = 2.69 (s, 12 H), 3.14 (s, 12 H),
2
2
3
+
73.2 (63) (1bH ).
4
.84 (d, 4 H, J = –5.7 Hz), 4.92 (d, 4 H, J = –5.7 Hz), 5.01 (d, 4 H,
J = –7.0 Hz), 5.11 (d, 4 H, J = –7.0 Hz), 7.09 (d, 4 H, J = 8.2 Hz),
.16 (d, 4 H, J = 8.5 Hz), 7.22 (ddd, 8 H, J = 8.2, 6.7, 1.2 Hz), 7.34
ddd, 4 H, J = 8.2, 6.7, 1.2 Hz), 7.43 (ddd, 4 H, J = 8.2, 6.7, 1.2 Hz),
.59 (d, 4 H, J = 9.1 Hz), 7.87 (d, 4 H, J = 8.2 Hz), 7.88 (d, 4 H,
J = 8.2 Hz), 7.99 (d, 4 H, J = 9.1 Hz), 8.18 (dd, 4 H, J = 8.2, 2.1 Hz), Acknowledgement
.26 (s, 4 H), 8.31 (d, 4 H, J = 8.2 Hz), 8.84 (d, 4 H, J = 2.1 Hz).
Anal. Calcd for the perchlorate C108H AgClN O 3CH OH: C,
64
4
12
3
7
(
7
7
2.10; H, 4.14; N, 3.03. Found: C, 71.70; H, 3.84; N, 2.90.
8
We thank Prof. Dr. P. Köll for providing us with excellent working
conditions and his steady interest in our research. We thank Prof.
Dr. J.-O. Metzger for the opportunity to perform the ESI-MS expe-
riments. Financial support from the DFG and the Fonds der Chemi-
schen Industrie is gratefully acknowledged. M. H. thanks the state
of Lower Saxony for a graduate scholarship.
1
3
C NMR (CD Cl2 CD CN, 6:1): = 56.0, 56.5, 88.8, 93.6, 95.2,
2
3
9
1
1
9.3, 116.5, 116.6, 119.6, 122.6, 122.8, 124.3, 125.3, 126.1, 126.1,
26.8, 126.8, 128.1, 128.2, 129.9, 130.3, 130.6, 134.0, 134.5, 134.8,
41.3, 150.1, 152.6, 153.1, 153.2.
+
+
ESI-MS: m/z (%) = 2004.5 (100) [Ag1a ] , 951.4 (54) [1a+H] .
2
Anal. Calcd for perchlorate C124H AgClN O CH Cl CH OH: C,
96
4
20
2
2
3
6
8.10; H, 4.63; N, 2.52. Found: C, 68.30; H, 4.67; N, 2.97.
Synthesis 2002, No. 15, 2289–2295 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Bis(BINOL) Substituted 2,2 -Bipyridines
2295
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(
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(
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(
(
(
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(
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2
(
(
(
19) Enantiomerically pure BINOL was obtained by resolution of
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(
7) Molecular modelling was performed using commercially
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(
8) Grosshenny, V.; Romero, F. M.; Ziessel, R. J. Org. Chem.
1
997, 62, 1491.
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(
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6
(
2
2
4
252. (b) A TMEDA-free procedure leading exclusively to
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(
(
11) Lützen, A.; Hapke, M. Eur. J. Org. Chem. 2002, 2292.
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16) The homodimerisation is usually finished after a few hours
as indicated by thin-layer chromatography. However
prolonged heating resulted in increased formation of by-
products. Also change of the solvent from DMF to THF gave
only a mixture of unreacted chloropyridine and 3.
Zhang, K. S.; Wang, D.; Guo, D. W.; Yang, X. Z. Chirality
001, 13, 595; however the yield of 4, which can be obtained
2
(
(
(
through this procedure is still in the same order of
magnitude.
(
22) Hegedus, L. S. In Organometallics in Synthesis; Schlosser,
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(
(
(
(
Synthesis 2002, No. 15, 2289–2295 ISSN 0039-7881 © Thieme Stuttgart · New York