Homo- vs. heterometallic organoaluminum fencholates: Structures and selectivities

Article abstract of DOI:10.1016/j.jorganchem.2008.03.013

Homo (Al)- and heterometallic (Al, Li)-fencholates and TADDOLates (5-12) yield in methylations of benzaldehyde 1-phenylethanol with up to 90% ee. Surprisingly, the new BISFOL-based (Al, Li)-heterometallic fencholate (11) shows an strong increase and a change of the sense of enantioselectivity from 19% ee (S) to 62% ee (R) in comparison to its (Al)-homometallic fencholate (7). Despite of the presence of nucleophilic methylide groups, the O-BIFOL-based (Al, Li)-heterometallic fencholate (10) yields a stable complex with benzaldehyde, a lithium ion binds the carbonyl group.

Full text of DOI:10.1016/j.jorganchem.2008.03.013

Journal of Organometallic Chemistry 693 (2008) 2139–2146
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Homo- vs. heterometallic organoaluminum fencholates: Structures and selectivities
1
*
Francis Soki, Jörg-Martin Neudörfl , Bernd Goldfuss
Department für Chemie, Universität zu Köln, Greinstrasse 4, D-50939 Köln
a r t i c l e i n f o
a b s t r a c t
Article history:
Homo (Al)- and heterometallic (Al, Li)-fencholates and TADDOLates (5–12) yield in methylations of benz-
aldehyde 1-phenylethanol with up to 90% ee. Surprisingly, the new BISFOL-based (Al, Li)-heterometallic
fencholate (11) shows an strong increase and a change of the sense of enantioselectivity from 19% ee (S)
to 62% ee (R) in comparison to its (Al)-homometallic fencholate (7). Despite of the presence of nucleo-
philic methylide groups, the O-BIFOL-based (Al, Li)-heterometallic fencholate (10) yields a stable com-
plex with benzaldehyde, a lithium ion binds the carbonyl group.
Received 21 January 2008
Received in revised form 11 March 2008
Accepted 11 March 2008
Available online 16 March 2008
Keywords:
Aluminum
Ó 2008 Elsevier B.V. All rights reserved.
Lithium
Fencholates
Alkylations
Enantioselectivity
Heterometallic reagents
1
. Introduction
Enantioselective alkylations of carbonyl compounds with orga-
ture of the Lewis acid MAD [8] (methylaluminum bis(2,6-di-tert-
butyl-4-methylphenoxide)) with 2,2-dimethylpropanal as Lewis
base (Scheme 2) [9]. Scott et al. reported the X-ray crystal structure
of a Lewis acid–base complex between the bulky homobimetallic
aluminum complex and benzaldehyde (Scheme 2) [10].
Recently, Maruoka et al. evaluated the reactivity of the alumi-
num Lewis acid A (Scheme 3) in comparison to the bis-aluminum
Lewis acid B in the alkylation of benzaldehyde with trimethylalu-
minum [11]. They found that the bimetallic Lewis acid B alkylates
benzaldehyde more rapidly and more efficiently than the mono-
metallic Lewis acid A.
nometallic reagents are among the most useful methods for the
preparation of chiral alcohols [1]. Additions of organolithiums to
aldehydes (Scheme 1) are synthetically well established and afford
enantiopure alcohols in the presence of stoichiometric amounts of
chiral additives. Catalytic procedures, e.g. with less than 5 mol%
of chiral additives, are hardly achievable, due to the high reactivity
of non-modified organolithiums towards aldehydes [1a,1b,1l].
In contrast, dialkylzinc reagents react with aldehydes extremely
slowly in the absence of a catalyst [2]. Chiral ligands, e.g. b-amino
alcohols [3], enable the catalytic asymmetric addition of dialkyl-
zinc to aldehydes with high enantioselectivities [4].
Unlike the dialkylzinc addition to aldehydes, organoaluminum
reagents are known to add rapidly to aldehydes, e.g. benzaldehyde,
at room temperature in the absence of any additives [5]. Benzalde-
hyde forms, e.g., with one equivalent trimethylaluminum in
dichloromethane at ꢀ78 °C a monomeric 1:1 complex, which sub-
sequently reacts to 1-phenylethanol at ꢀ20 °C [6]. Molecular struc-
tures of such complexes can provide explanations for the mode of
coordination of organic carbonyls to aluminum, but only few
examples of such Lewis acid–base complexes with aldehydes are
known in the literature [7]. Barron et al. reported the X-ray struc-
A series of aluminum reagents and catalysts based on chiral
chelating C -symmetric diols such as BINOLs C [12], TADDOLs D
2
[13] and its derivates (Scheme 3) have been synthesized and play
as Lewis acids a fundamental role in the synthesis of optically pure
compounds [14].
Shibasaki and co-workers also developed a series of heterobi-
metallic [15] complexes based on BINOL and demonstrated their
potential as multifunctional catalysts, e.g. ALB: aluminum lithium
bis (binaphthoxide) in several catalytic asymmetric reactions, e.g.
aldol additions [16].
We have recently employed modular fencholates [17] in chiral
organolithium [1a,1b,18] reagents as well as in organozinc [19],
organocopper [20] and organopalladium [21] catalysts to study
origins of enantioselectivities in C–C-couplings. Herein, we present
new fenchone based chiral organoaluminum reagents, their appli-
cation as methylide transfer reagent to alkylate benzaldehyde and
*
Corresponding author. Fax: +49 221 470 5057.
E-mail address: goldfuss@uni-koeln.de (B. Goldfuss).
X-ray analyses.
+
3+
study the influence of the metal ions, i.e. Li vs. Al in homo- and
heterometallic systems.
1
0
022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.03.013

2
140
F. Soki et al. / Journal of Organometallic Chemistry 693 (2008) 2139–2146
1
) R M
n
L*
M= Li (n=1)
Zn (n=2)
O
HO
Ph
R
∗
H
Al (n=3)
Ph
H
2) H
2
O
Scheme 1. Enantioselective addition of organometallic reagents to benzaldehyde
*
with the chiral ligand L . Organolithiums and organoaluminums add to benzalde-
hyde in the absence of any additives. Organozinc reagents react extremely slowly in
the absence of a catalyst.
O
Al
O
O
iPr
iPr
tBu
Me
Al
O
H
6
H
O
tBu
tBu
tBu
tBu
tBu
O
Me
O
O
O
Al
O
Al
Me
tBu
iPr
O
iPr
Fig. 1. X-ray crystal structure of 6. The phenyl group of the diphenylether moiety is
fixed between the methyl group and the methylene bridge at C1 of the bicy-
clo[2.2.1]-heptane scaffold. Hydrogen atoms are omitted for clarity and the prob-
ability of the thermal ellipsoids is 30%.
tBu
Ph
MAD
Barron-complex
Scott-complex
Scheme 2. Literature known molecular structures of the complexes of aluminum
organyls with aldehydes from Barron and Scott.
num with the suspensions of diols (M)-BIFOL [17d] (1), O-BIFOL
[
22] (2), BISFOL [17b] (3) and TADDOL [23] (4) (Scheme 4). In addi-
tion to three fencholate-based diols, TADDOL (4) was used as a
prominent chiral diol with sterically crowded hydroxyl groups,
similar to BIFOL.
Al
O
Al
O
Al
O
Ph Ph
O
O
O
O
O
O
Al
Al
The molecular structures of the organoaluminum reagents (6–
R
R
8) were confirmed by single-crystal X-ray diffraction (Figs. 1–3).
Ph Ph
All three crystal structures show tetra coordinated aluminum ions
and form well defined chelate rings. The molecular structure of 7
A
B
C
D
(
Fig. 2) is, in contrast to the homometallic aluminum complexes
Scheme 3. Homometallic organoaluminum reagents as Lewis acids for the activa-
tion of the carbonyl moiety.
6 and 8, a homobimetallic aluminum complex whereas each Al-
ion is joined by the oxygen atom of the fenchyl moiety (Al–O1:
1
.72 Å) and of the sulfone group (Al–O3: 1.94 Å) and two further
methylide groups (Al–C: 1.95 Å). In all fencholate based structures
Figs. 1 and 2) aryl groups are conformationally fixed between the
2
. Results and discussion
(
The chiral, enantiopure organoaluminum compounds 5–8 are
accessible from reactions of toluene solutions of trimethylalumi-
methyl group and the methylene bridge at C1 of the fenchane scaf-
folds [17–20].
O Al
O Al
Ph Ph
O
Al
O
O
O
O
O
O
O
AlMe
Toluene, RT
3
Al
SO
2
O
Al
Ph Ph
OH
5
6
7
8
*
OH
n-BuLi (1eq)
O
Li
Ph Ph
O
O Al
Ph Ph
AlMe
3
(1eq)
O Li
O
O Al
Li
O
O
O
Li
Toluene, RT
SO
2
O Al
O Al
9
10
11
12
OH
OH
OH
Ph Ph
OH
OH
Ph Ph
OH
OH
O
O
SO
2
OH
OH
O
*
=
OH
Chiral diol
BIFOL (1)
O-BIFOL (2)
BISFOL (3)
TADDOL (4)
Scheme 4. Chiral homo (Al)- and heterometallic (Al, Li) reagents, accessible from diols, trimethylaluminum and n-butyllithium.

F. Soki et al. / Journal of Organometallic Chemistry 693 (2008) 2139–2146
2141
O Al
SO2
O Al
7
Fig. 2. X-ray crystal structure of 7. The phenyl group of the cyclic sulfone is fixed
between the methyl group and the methylene bridge at C1 of the bicyclo[2.2.1]-
heptane scaffold. Hydrogen atoms are omitted for clarity and the probability of the
thermal ellipsoids is 30%.
Scheme 5. Alkylation of benzaldehyde by homometallic (Al, grey)-and heterome-
tallic (Al, Li, white) reagents (5–12).
Ph Ph
O
O
Al
O
O
O
Table 1
Ph Ph
Alkylation of benzaldehyde by homo-and heterometallic reagents (5–12) according to
Scheme 5
8
ꢀ1
Reagents
% Yielda
% ee (Config.)b
m (CO) (cm )c
BIFOL-Al (5)
O-BIFOL-Al (6)
BISFOL-Al (7)
TADDOL-Al (8)
BIFOL-Al-Li (9)
O-BIFOL-Al-Li (10)
BISFOL-Al-Li (11)
TADDOL-Al-Li (12)
43
45
65
12
57
55
73
35
5 (R)
5 (R)
19 (S)
90 (R)
5 (R)
5 (R)
62 (R)
1 (R)
1662
1702
1698
1695
1652
1700
1661
1691
Fig. 3. X-ray crystal structure of 8. Hydrogen atoms are omitted for clarity and the
probability of the thermal ellipsoids is 30%.
a
Isolated yield of 1-phenylethanol by a reaction time of 6 h (ꢀ20 °C) in toluene.
The enantiomeric excess was analyzed by GC (Chiraldex G-TA column).
Carbonyl stretching frequencies of the toluene solutions of the homo- and
Addition of one equivalent of a hexane solution of n-butyllith-
ium and one equivalent of a toluene solution of trimethylalumi-
num to the suspensions of 1–4 in toluene at room temperature
under argon atmosphere and subsequent stirring afforded the
b
c
heterometallic reagents (5–12) with benzaldehyde (0 °C, neat, benzaldehyde m (CO):
ꢀ
1
1699 cm ).
(
Al, Li)-heterometallic complexes 9–12 (Scheme 4).
To gain information on the reactivity and selectivity of the (Al)-
homo- and (Al, Li)-heterometallic organyls (5–12) in alkylations of
carbonyl compounds, the methylation of benzaldehyde with these
compounds was used as model reaction (Scheme 5).
metallic compounds 9 (5% ee, 57% yield) and 10 (5% ee, 55% yield)
in comparison to (Al)-homometallic (5) (5% ee, 43% yield) and (6)
(5% ee, 45% yield), the introduction of lithium as second metal
ion gives rise to a surprisingly strong and also change of the sense
of the enantioselectivity for (Al, Li)-BISFOL (11) (62% ee R, 73%
yield) vs. (Al)-BISFOL (7) (19% ee S, 65% yield; Scheme 5, Table
1). This dramatic increase of the enantioselectivity points to a
modified coordination of the carbonyl group in the substrate by
the Lewis-acidic reagent. Indeed, IR-spectroscopic investigation
of a toluene solutions of the (Al, Li)-heterometallic fencholate
(11) with benzaldehyde exhibits a strong decrease of the carbonyl
Treatment of benzaldehyde with the in situ prepared reagents
(
5–8) in toluene at ꢀ20 °C for 6 h afforded after hydrolytic work-
up 1-phenylethanol in 12–73% yield and in 5–90% ee (Scheme 5,
Table 1). While (Al)-BIFOL (5) and (Al)-O-BIFOL (6) provide only
5
% ee of the R-enantiomeric product, (Al)-BISFOL (7) yields 1-phen-
ylethanol with 19% ee (S-enantiomer). In contrast to other
Al)-homometallic organoaluminum complexes (5, 6 and 8), (Al)-
(
BISFOL (7) provides the best reactivity (65%), pointing to a strong
electrophilic activation of the carbonyl moiety by the two Lewis-
acidic aluminum ions in 7. The TADDOL based Al-organyl (8)
provides the highest enantioselectivity (90% ee) but shows only a
low yield (12%).
ꢀ1
stretching frequency (1661 cm , Table 1), compared to the (Al)-
ꢀ
1
homometallic fencholate (7) with benzaldehyde (1698 cm ). This
points to a stronger coordination of the carbonyl oxygen atom to
the lithium ion in (Al, Li)-heterometallic fencholate (11) relative
to the aluminum ions of (Al)-homometallic (7). In contrast to 11
and 7, the (Al, Li)-heterometallic TADDOLate (12) exhibits a
While no enhancement of the enantioselectivities and only a
slight increase of the reactivities are observed with (Al, Li)-hetero-

2
142
F. Soki et al. / Journal of Organometallic Chemistry 693 (2008) 2139–2146
strongly decreased enantioselectivity for the methylation of benz-
aldehyde (35% yield, 1% ee) in comparison to the (Al)-homometal-
lic TADDOLate (8) (12% yield, 90% ee). Attempts to crystallize the
heterometallic reagents 11 and 12 both at room temperature and
Ph Ph
Ph Ph
O
O
O
O
O
O
O
O
Al
Li
ꢀ
20 °C yielded no suitable crystals for X-ray analyses. However,
the reaction of n-butyllithium with a hexane solution of BISFOL
3) at 0 °C and recrystallization from hexane yields a macrocyclic,
dimeric, C -symmetric alkyllithium complex (13) with four tetra
Ph Ph
Ph Ph
(
O
O
2
1
5
coordinated lithium ions. Each lithium ion coordinates to two oxy-
gen atoms of the alkoxide moieties and two oxygen atoms of the
sulfone group (Fig. 4).
Fig. 6. X-ray crystal structure of TADDOL-lithiumaluminate (15). Hydrogen atoms
are omitted for clarity. Thermal ellipsoids represent a 30% probability. Selected
atom distances (in Å): Al–O3 1.71, Al–O4 1.75, Al–O5 1.71, Al–O6 1.75, Li–O4 2.07,
Li–O6 2.03, Li–O9 1.93, Li–O10 1.97.
2
Another macrocyclic, dimeric, C -symmetric alkyllithium com-
plex was obtained by the reaction of n-butyllithium with a tetrahy-
drofuran solution of TADDOL (4) at 0 °C and recrystallization from
hexane. The molecular structure of the complex shows two tri-
coordinated lithium ions whereas each lithium ion coordinates to
two oxygen atoms of the alkoxide moieties and one oxygen atom
of the THF-molecule. The core of this complex consists of a lith-
ium-bridged and hydrogen-bonded Li
Fig. 5) [24].
Attempts to isolate a (Al, Li)-heterometallic reagent based on
TADDOL yields the unprecedented [17a,25,26] lithium aluminate
2 4 2
O H eight-membered ring
(
3
+
(
15), in which Al is coordinated by two TADDOLate units and
O
H
O
+
the Li ion bridges two of the alkoxide ions. Free coordination sites
at Li are coordinated by THF (Fig. 6).
Al
O
Li
+
O
The (Al, Li)-heterometallic fencholate (10) provides both a low
reactivity and selectivity (55% yield and 5% ee). The nucleophilic
methylide groups of the O-BIFOL-based (Al, Li)-heterometallic
fencholate (10) are both quite distant to and especially ‘‘in plane”
of the formyl group of benzaldehyde (Fig. 7), this ‘‘symmetry-for-
1
0
*
bidden” arrangement of the Me-nucleophiles to the p -carbonyl
acceptor explains moderate yields of methylation. The low enanti-
oselectivity of 10 points to a non-complexed and not preorganized
aldehyde substrate ion during the reaction. A rare example of a
Fig. 7. X-ray crystal structure of 10 with benzaldehyde. Hydrogen atoms are omi-
tted for clarity except the hydrogen atoms of the endo methyl group of one fenc-
hane unit and the hydrogen atom of benzaldehyde. The probability of the thermal
ellipsoids is 30%. Selected atom distances (in Å): Li–O1 1.91, Li–O2 2.07, Li–O3 1.92,
Li–O4 1.92, Li–H1 2.27, Li–H2 2.44, Al–O2 1.78, Al–O4 1.79, CAl–Ccarb 4.8; 7.2.
Li
O
O
SO
2
Li
O2S
Li
Li
well defined aldehyde complex with a methyl aluminum Lewis
acid is apparent from a X-ray crystal structure analysis of a com-
plex of the (Al, Li)-heterometallic O-BIFOL reagent (10) with benz-
aldehyde (Fig. 7). This Lewis acid–base complex represents the first
isolated and structurally characterized enantiopure complex of
benzaldehyde with a lithium dimethylaluminate [27]. At the core
O
O
1
3
2
of the structure is a AlO Li four-membered ring (Al–O2: 1.78 Å,
Fig. 4. X-ray crystal structure of BISFOL-Li. Hydrogen atoms are omitted for clarity
and the probability of the thermal ellipsoids is 30%. Selected atom distances (in Å):
Al–O4: 1.79 Å, Li–O2: 2.07 Å, Li–O4: 1.92 Å). The lithium ion is
coordinated by three oxygen atoms of the O-BIFOL ligand and by
one oxygen atom of the external Lewis base benzaldehyde.
The Li–H distances between the endo methyl group of the
fenchane unit and the Li-ion are short (Li–H1: 2.27 Å, Li–H2:
0
Li1–O1 2.10, Li1–O2 1.91, Li1–O3 1.90, Li1–O4 2.10, Li2–O2 2.02, Li2–O4 2.02, Li3–
0
0
0
O1: 2.03, Li3–O3 2.00; Li4–O1 2.10, Li4–O2 1.91, Li4–O3 1.90, Li4–O4 2.10.
2
.44 Å) and point to the tendency of ‘‘agostic” Li–HC interactions;
all other Li–H distances are >2.50 Å [28].
O
Ph Ph
Ph Ph
O
O
Li
O
O
3
. Conclusions
O
O
O
O
HH
Li
Ph Ph
Ph Ph
Besides the (Al)-homometallic organoaluminum reagents,
O
(Al, Li)-heterometallic methylation reagents based on fenchols
and TADDOL can be employed in methylation of benzaldehyde.
Methylations with 5–12 afford 1-phenylethanol in up to 73% yield
and 90% ee. The homometallic TADDOLate (8) reaches the highest
enantioselectivity (90%) amongst the (Al)-homometallic reagents
but provides only a low yield (12%). The introduction of lithium
as second metal ion gives rise to a dramatic enhancement and also
a change in the sense of the enantioselectivity for (Al, Li)-BISFOLate
14
Fig. 5. X-ray crystal structure of Li-TADDOLate (14). Hydrogen atoms are omitted
for clarity except H1 and H2. Thermal ellipsoids represent a 30% probability. Sele-
cted atom distances (in Å): O3–H1 1.47, O6–H2 1.43, O3–O4 2.44, O5–O6 2.42, Li1–
O3 1.86, Li1–O5 1.82, Li1–O9 1.89, Li2–O4 1.85, Li2–O6 1.86, Li2–O10 1.90.

F. Soki et al. / Journal of Organometallic Chemistry 693 (2008) 2139–2146
2143
(
11) (62% ee) vs. (Al)-BISFOLate (7) (19% ee). The (Al, Li)-hetero-
the solution to ꢀ78 °C and thawing three times, the precipitate
formed was dissolved in hot toluene. Slow cooling to room temper-
ature yielded 7 (0.79 g, 65%) as colorless crystals. m.p.: >281 °C
metallic O-BIFOLate (10) forms a stabile and structurally charac-
terized Lewis acid–base complex with benzaldehyde. This
demonstrates the high Lewis-acidity of the (Al, Li)-heterometallic
complexes and their tendency to coordinate Lewis bases, such as
aldehydes, via the lithium ion.
2
0
ꢀ1
(decomposition); ½aꢁ ¼ ꢀ130 (c = 0.1 in toluene); IR (KBr, cm
)
D
1
3523 (b), 2924, 1572, 1456. H NMR (CDCl
3
, 300 MHz): d = 0.15
(6H, s), 0.58 (3H, s), 1.12–1.60 (3H, m), 1.23–1.34 (4H, m), 1.45–
.60 (2H, m), 1.81 (1H, d), 1.96 (1H, d), 2.43 (2H, s), 7.24-7.33
1
1
3
(
3
1H, dd), 7.70–7.80 (1H, m), 7.89–8.05 (1H, m). C NMR (CDCl ,
4
. Experimental
7
8
1
5 MHz) d = 145.50, 137.37, 132.49, 131.99, 130.74, 119.09,
6.04, 54.49, 48.86, 47.74, 42.72, 33.64, 29.56, 23.95, 21.23,
7.64, 1.52. X-ray crystal data of 7: C43 S, M = 724.91;
22; a = 10.4517(7) Å, b = 10.4517(7) Å, c =
All reactions were carried out under argon atmosphere (by
2 4
H58Al O
using Schlenk and needle/septum techniques) with dried and de-
gassed solvents. X-ray crystal analyses were performed on a Bruker
Nonius-Kappa-CCD diffractometer with use of Mo Ka radiation,
NMR spectra were recorded on a Brucker DPX 300 instrument, IR
spectra on a Perkin Elmer paragon 1000 FT-IR spectrometer, melt-
ing point on a Stuart Scientific SMP3 machine and optical rotations
space group P4
6.343(2) Å, V = 3970.0(4) Å ; Z = 4; T = 100(2) K; l = 0.166 mm
1
3
ꢀ1
3
;
reflections total: 11769, unique: 3662, observed: 2070 (I > 2r(I));
parameters refined: 284; R1 = 0.0473, wR2 = 0.0701; GOF = 0.863.
4.4. Synthesis of methylaluminum TADDOLate (8)
on an IBZ polar L
l
P-WR machine. GC analyses were carried out on
a Hewlett Packard HP 6890 instrument.
A solution of trimethylaluminum (1.07 mL, 2.14 mmol, 2.0 M in
toluene) was added at room temperature to a solution of TADDOL
1.0 g, 2.14 mmol) in toluene (3 mL). The resulting mixture was
0
4
.1. Synthesis of methylaluminumbiphenyl-2,2 -bisfencholate (5)
(
stirred for 2 h. After cooling the solution to ꢀ78 °C and thawing
three times, the precipitate formed was dissolved in hot toluene.
Slow cooling to room temperature yielded 8 (0.92 g, 85%) as color-
A solution of trimethylaluminum (1.1 mL, 2.2 mmol, 2.0 M in
toluene) was added at room temperature to a solution of biphe-
0
nyl-2,2 -bisfenchol (BIFOL) (1.0 g, 2.2 mmol) in toluene (3 mL).
2
0
less crystals. m.p.: >193 °C (decomposition); ½aꢁ ¼ ꢀ66 (c = 0.2 in
D
The resulting mixture was stirred for 2 h. After cooling the solution
to ꢀ78 °C and thawing three times, the precipitate formed was dis-
solved in hot toluene. Slow cooling to room temperature yielded 5
ꢀ1
1
toluene), IR (KBr, cm ) 3284 (b), 2983, 1598, 1493, 1445. H NMR
(
(
CDCl
1H, s), 7.18 (5H, s) 7.27–7.37 (16H, m) 7.57 (4H, d), C NMR
75 MHz) d = 145.98, 142.74, 128.63, 128.11, 127.64,
127.55, 127.28, 109.51, 80.98, 77.46, 27.15. X-ray crystal data of
39AlO , M = 578.65; space group P2 ; a = 9.3849(2) Å,
b = 15.8649(5) Å, c = 20.3281(6) Å, V = 3026.66(15) Å ; Z = 4; T =
3
, 300 MHz): d = 0.14 (3H, s), 0.96 (6H, s), 4.09 (1H, s), 4.25
13
(
0.88 g, 80 %) as white powder. m.p.: >245 °C (decomposition);
20
D
ꢀ1
3
(CDCl ,
½
aꢁ ¼ ꢀ125 (c = 0.2 in toluene); IR (KBr, cm ) 3548 (s), 3423
1
(
b), 2924, 1472. H NMR (toluene-d
.65 (3H, s), 0.70 (3H, s), 1.10 (3H, s), 1.30–2.35 (6H, m), 2.35
3H, s), 6.91 (1H, d), 7.10 (1H, t), 7.23 (1H, t), 7.62 (1H, d).
8
, 300 MHz): d = ꢀ0.79 (3H, s),
8
: C36
H
5
1 1 1
2 2
0
(
3
1
3
C
ꢀ1
1
00(2) K; l = 0.110 mm ; reflections total: 16841, unique: 6557,
8
NMR (toluene-d , 75 MHz) d = 144.45, 141.52, 131.62, 130.23,
25.41, 125.20, 86.52, 54.99, 49.58, 46.80, 42.75, 34.48, 30.29,
4.06, 21.42, 17.87, ꢀ4.33.
observed: 4922 (I > 2r(I)); parameters refined: 382; R1 = 0.0413,
wR2 = 0.0733; GOF = 0.952.
1
2
0
4
.5. Synthesis of lithiumdimethylaluminumbiphenyl-2,2 -
0
4
.2. Synthesis of methylaluminumbiphenylether-2,2 -bisfencholate
bisfencholate (9)
(6)
A solution of n-BuLi (1.4 mL, 2.2 mmol, 1.6 M in hexane) was
added at room temperature to a solution of biphenyl-2,2 -bisfen-
chol (BIFOL) (1.0 g, 2.2 mmol) in toluene (3 mL). The resulting mix-
A solution of trimethylaluminum (1.1 mL, 2.1 mmol, 2.0 M in
0
toluene) was added at room temperature to a solution of bipheny-
0
lether-2,2 -bisfenchol (O-BIFOL) (1.0 g, 2.1 mmol) in toluene
ture was stirred for 2 h. To this mixture,
a solution of
(
3 mL). The resulting mixture was stirred for 2 h. After cooling
trimethylaluminum (1.1 mL, 2.2 mmol, 2.0 M in toluene) was
added at room temperature and the solution was stirred for further
the solution to ꢀ78 °C and thawing three times, the precipitate
formed was dissolved in hot THF. Slow cooling to room tempera-
ture yielded 6 (0.83 g, 77%) as colorless crystals. m.p.: >270 °C
2
h. Slow evaporation of the solvent yielded 9 (0.95 g, 83%) as
20
white powder. m.p.: >299 °C (decomposition); ½aꢁ ¼ ꢀ74 (c = 0.2
2
D
0
ꢀ1
D
(
3
(
7
1
4
decomposition); ½aꢁ ¼ ꢀ112 (c = 0.3 in toluene); IR (KBr, cm
)
ꢀ1
in toluene), IR (KBr, cm ) 3548 (s), 3418 (b), 2922, 1662, 1471,
1
487 (s), 2924, 1477, 1436. H NMR (CDCl
3
, 300 MHz): d = 0.29
1
1
381. H NMR (toluene-d
8
, 300 MHz): d = ꢀ0.29 (6H, s), 0.29 (3H,
3H, s), 0.54–0.70 (6H, s), 1.00–1.74 (18H, m), 2.43 (8H, s), 7.00–
s), 0.33 (3H, s), 0.58 (3H, s), 0.96 (2H, d), 1.00 (3H, s), 1.32 (2H,
s), 1.41 (2H, s), 1.44 (3H, s), 1.55 (2H, s), 1.68 (2H, s), 1.76 (2H,
.50 (6H, m), 7.84 (2H, d). 13C NMR (CDCl
3
, 75 MHz) d = 137.85,
31.66, 129.02, 128.21, 125.29, 113.55, 92.90, 86.33, 56.05, 49.63,
7.29, 41.99, 34.21, 29.91, 23.81, 21.47, 17.74. X-ray crystal data
s), 2.27–2.34 (1H, m), 2.46 (1H, s), 6.63–6.67 (1H, m), 6.78–6.84
13
(
7
8
8
2H, m), 7.12 (3H, s), 7.69–7.74 (2H, m). C NMR (toluene-d ,
of 6: C33
3 1
H43AlO , M = 514.65; space group P2 ; a = 10.1607(4) Å,
5 MHz) d = 144.18, 141.23, 131.42, 130.07, 129.09, 124.69,
6.22, 54.81, 49.20, 46.49, 42.39, 34.25, 30.27, 23.93, 21.38, 17.85.
b = 18.2498(9) Å, c = 15.3081(5) Å, b = 101.817(2), V = 2778.4(2)
3
ꢀ1
Å ; Z = 4; T = 100(2) K; l = 0.106 mm ; reflections total: 13511,
unique: 10620, observed: 7713 (I > 2r(I)); parameters refined:
0
4
.6. Synthesis of lithiumdimethylaluminumbiphenylether-2,2 -
7
45; R1 = 0.0501, wR2 = 0.0957; GOF = 0.996.
bisfencholate (10)
0
0
4
.3. Synthesis of tetramethylaluminumbiphenyl-2,2 -sulfone-3,3 -
A solution of n-BuLi (1.4 mL, 2.2 mmol, 1.6 M in hexane) was
added at room temperature to a solution of biphenylether-2,2 -bis-
0
bisfencholate (7)
fenchol (O-BIFOL) (1.04 g, 2.2 mmol) in toluene (3 mL). The result-
ing mixture was stirred for 2 h. To this mixture, a solution of
trimethylaluminum (1.1 mL, 2.2 mmol, 2.0 M in toluene) was
added at room temperature and the solution was stirred for further
2 h. Slow evaporation of the solvent yielded 10 (1.0 g, 86%) as
A solution of trimethylaluminum (1.92 mL, 3.84 mmol, 2.0 M in
toluene) was added at room temperature to a solution of biphenyl-
0
0
2
,2 -sulfone-3,3 -bisfenchol (BISFOL) (1.0 g, 1.92 mmol) in toluene
(
3 mL). The resulting mixture was stirred for 2 h. After cooling

2
144
F. Soki et al. / Journal of Organometallic Chemistry 693 (2008) 2139–2146
2
D
0
white powder. m.p.: >287 °C (decomposition); ½aꢁ ¼ ꢀ121 (c = 0.1
solved in hot hexane. Slow cooling to room temperature yielded
crystals suitable for X-ray analysis. m.p.: 171 °C (decomposition),
ꢀ1
1
in toluene), IR (KBr, cm ) 3482 (b), 2924, 1593, 1477, 1437.
H
NMR (toluene-d
(
(
8
, 300 MHz): d = ꢀ0.35 (6H, s), 0.29 (3H, s), 0.68
3H, s), 0.81-0.887 (3H, m), 1.01 (3H, t), 1.02 (3H, d), 1.14–131
3H, m), 165 (2H, s), 1.87 (2H, s), 2.30 (2H, d), 2.78 (2H, d), 3.14–
X-ray crystal data of Li-BISFOLate: C37
group a = 24.295(2) Å, b = 11.8729(5) Å, c = 13.5915(10) Å,
b = 120.033(1), V = 3394.2(4) Å ; Z = 4; T = 100(2) K; l = 0.131
mm ; reflections total: 7768, unique: 5625, observed: 3991
(I > 2r(I)); parameters refined: 379; R1 = 0.0671, wR2 = 0.1581;
GOF = 0.985.
2 4
H38Li O S, M = 592.61; space
2
C ;
3
ꢀ1
3
7
1
1
4
2
.23 (2H, m), 3.05 (1H, s), 6.81 (1H, s), 6.88 (2H, t), 7.12 (3H, s),
.72 (2H, t). C NMR (toluene-d , 75 MHz) d = 157.34, 155.07,
8
35.27, 135.20, 129.90, 129.68, 128.98, 126.71, 123.24, 122.97,
21.12, 117.88, 85.45, 84.99, 53.62, 53.38, 50.16, 49.21, 45.55,
4.76, 41.13, 40.58, 33.94, 33.36, 30.36, 29.75, 24.59, 24.39,
2.45, 22.34, 18.31, 18.16.
1
3
4.11. Synthesis and characterization of Li-TADDOLate (14)
TADDOL (4) (1.0 g, 2.14 mmol) was added at room temperature
to n-BuLi (2.7 mL, 4.30 mmol, 1.6 M solution in hexane), and the
mixture was stirred at 25 °C for 3 h. After cooling the solution to
4
1
.7. Synthesis and characterization of the benzaldehyde complex with
0
ꢀ
78 °C and thawing three times, the precipitate formed was dis-
solved in hot THF. Slow cooling to room temperature yielded crys-
Benzaldehyde (0.2 g, 1.89 mmol) and 10 (1.0 g, 1.89 mmol)
were dissolved in toluene (3 mL) at room temperature. The mix-
ture was stirred for 5 h at room temperature and the solution
was cooled to ꢀ20 °C. Yellow oil formed, which crystallized after
tals suitable for X-ray analysis. m.p.: 165 °C (decomposition), X-ray
crystal data of Li-TADDOLate: C152H176Li O20, M = 2350.69; space
4
group P2 ; a = 11.5093(4) Å, b = 15.7585(3) Å, c = 19.0123(5) Å,
1
3
2
days. Slow evaporation of the solvent yielded crystals suitable
b = 105.092(1), V = 3329.31(16) Å ; Z = 1; T = 100(2) K; l = 0.076
ꢀ1
for X-ray analysis. m.p.: 198 °C (decomposition), X-ray crystal data
of benzaldehyde 10 complex: C41 52AlLiO , M = 642.75; space
group P2 ; a = 9.7197(6) Å, b = 16.866(2) Å, c = 21.538(2) Å,
mm ; reflections total: 11993, unique: 11993, observed: 7979
(I > 2r(I)); parameters refined: 807; R1 = 0.0702, wR2 = 0.1500;
GOF = 1.026.
H
4
1 1 1
2 2
3
ꢀ1
V = 3530.8(6) Å ; Z = 4; T = 100(2) K; l = 0.098 mm ; reflections
total: 16902, unique: 7487, observed: 3823 (I > 2r(I)); parameters
refined: 488; R1 = 0.0469, wR2 = 0.0618; GOF = 0.839.
4.12. Synthesis and characterization of TADDOL-lithiumaluminate
(15)
0
0
4
.8. Synthesis of lithiumdimethylaluminumbiphenyl-2,2 -sulfone-3,3 -
TADDOL (4) (1.0 g, 2.14 mmol) was added at room temperature
to LiAlH (0.9 mL, 2.14 mmol, 2.4 M solution in THF), and the mix-
ture was stirred at 25 °C for 3 h. After cooling the solution to
78 °C and thawing three times, the precipitate formed was dis-
solved in hot hexane. Slow cooling to room temperature yielded
crystals suitable for X-ray analysis. m.p.: 182 °C (decomposition),
bisfencholate (11)
4
A solution of n-BuLi (1.4 mL, 2.2 mmol, 1.6 M) in hexane was
added at room temperature to a solution of biphenyl-2,2 -sul-
fone-3,3 -bisfenchol (BISFOL) (1.14 g, 2.2 mmol) in toluene
3 mL). The resulting mixture was stirred for 2 h. To this mixture,
a solution of trimethylaluminum (1.1 mL, 2.2 mmol, 2.0 M) in tol-
uene was added at room temperature and the solution was stirred
for further 2 h. Slow evaporation of the solvent yielded 11 (1.1 g,
ꢀ
0
0
(
X-ray crystal data of TADDOL-lithiumaluminate: C76
H86AlLiO10,
M = 1193.37; space group P2 ; a = 12.5099(6) Å, b = 39.861(2) Å,
1
3
c = 13.5707(7) Å, b = 104.5330(1), V = 6550.6(6) Å ; Z = 4; T =
ꢀ1
1
00(2) K; l = 0.091 mm
;
reflections total: 27944, unique:
2
0
8
3%) as white powder. m.p.: >287 °C (decomposition); ½aꢁ
¼
D
2
4342, observed: 13317 (I > 2r(I)); parameters refined: 1597;
ꢀ1
ꢀ
145 (c = 0.3 in toluene), IR (KBr, cm ) 3523 (b), 2924, 1572,
R1 = 0.0623, wR2 = 0.1233; GOF = 0.909.
1
1
456. H NMR (toluene-d
8
, 300 MHz): d = ꢀ0.43 (6H, s), 0.58 (3H,
s), 1.08 (3H, s), 1.26 (3H, s), 1.43–2.38 (6H, m), 3.05 (1H, s), 7.52
1
3
4.13. General procedure for the alkylation of benzaldehyde with
homometallic reagents
(
1H, t), 7.70 (2H, d). C NMR (toluene-d
8
, 75 MHz) d = 145.09,
32.19, 131.61, 130.07, 128.98, 118.98, 54.28, 50.06, 48.85, 47.64,
2.42, 33.67, 29.67, 24.16, 21.38, 17.19.
1
4
A suspension of diol (1 mmol) was treated with a solution of
trimethylaluminum (1 or 2 mmol, 2.0 M in toluene) at room tem-
perature for 2 h. After cooling the solution at ꢀ20 °C, benzaldehyde
4
.9. Synthesis of lithiumdimethylaluminum-TADDOLate (12)
(
1 mmol) was added and the resulting mixture was stirred for 6 h
A solution of n-BuLi (1.4 mL, 2.2 mmol, 1.6 M) in hexane was
added at room temperature to a solution of (1.03 g, 2.2 mmol)
TADDOL in toluene (3 mL). The resulting mixture was stirred for
h. To this mixture, a solution of trimethylaluminum (1.1 mL,
.2 mmol, 2.0 M in toluene) was added at room temperature and
the solution was stirred for further 2 h. Slow evaporation of the sol-
at the same temperature. After quenching with water, the water
layer was extracted with 20 mL Et O. The combined organic layers
were dried over anhydrous Na SO . Filtration and distillation of the
2
2
4
2
2
solvents left yellow oil. The enantiomeric excess was analyzed by
GC (Chiraldex G-TA column).
vent yielded 12 (1.0 g, 85%) as white powder. m.p.: >296 °C
2
0
ꢀ1
(
decomposition); ½aꢁ ¼ ꢀ57 (c = 0.3 in toluene), IR (KBr, cm
)
4.14. General procedure for the alkylation of benzaldehyde with
heterometallic reagents
D
1
3
373 (b), 1493, 1444. H NMR (toluene-d
8
, 300 MHz): d = 0.95
(
7
6H, s), 1.56 (6H, s), 4.88 (2H, s), 7.04–7.50 (16, m), 7.53 (2H, d),
1
3
.70 (2H, d). C NMR (toluene-d
8
, 75 MHz) d = 146.59, 143.29,
A suspension of diol (1 mmol) was treated with a solution of n-
BuLi (1 mmol, 1.6 M in hexane) at room temperature for 2 h. To
this mixture, a solution of trimethylaluminum (1 mmol, 2.0 M in
toluene) was added at room temperature and the solution was stir-
red for further 2 h. After cooling the solution at ꢀ20 °C, benzalde-
hyde (1 mmol) was added and the resulting mixture was stirred for
6 hours at the same temperature. After quenching with water, the
1
29.02, 127.91, 127.07, 81.47, 78.12, 29.63, 26.95.
4.10. Synthesis and characterization of Li-BISFOLate (13)
BISFOL (3) (1.0 g, 1.92 mmol) was added at room temperature
to n-BuLi (2.4 mL, 3.84 mmol, 1.6 M solution in hexane), and the
mixture was stirred at 25 °C for 3 h. After cooling the solution to
water layer was extracted with 20 mL Et
2
O. The combined organic
. Filtration and distilla-
ꢀ78 °C and thawing three times, the precipitate formed was dis-
layers were dried over anhydrous Na SO
2
4

F. Soki et al. / Journal of Organometallic Chemistry 693 (2008) 2139–2146
2145
tion of the solvents left yellow oil. The enantiomeric excess was
analyzed by GC (Chiraldex G-TA column).
(b) T. Ooi, M. Takahashi, K. Marouka, Angew. Chem. 110 (1998) 875–877;
(
c) T. Ooi, M. Takahashi, K. Marouka, Angew. Chem., Int. Ed. 37 (1998) 835–
8
37.
12] (a) Applications of aluminum BINOLates as Lewis acids J.M. Brunel, Chem. Rev.
05 (2005) 857–898;
[
1
5
. Supplementary material
(
(
b) M. Roberson, A.S. Jepsen, K.A. Jørgensen, Tetrahedron 57 (2001) 907–913;
c) K.B. Jensen, M. Roberson, K.A. Jørgensen, J. Org. Chem. 65 (2000) 9080–
CCDC 663047, 663048, 663049, 663050, 663051, 663052 and
63053 contain the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/da-
ta_request/cif.
9084;
d) K.B. Simonsen, P. Bayón, R.G. Hazell, K.V. Gothelf, K.A. Jørgensen, J. Am.
Chem. Soc. 121 (1999) 3845–3853;
e) H. Suga, K. Ikai, T. Ibata, Tetrahedron Lett. 39 (1998) 869–872;
(f) A. Graven, M. Johannsen, K.A. Jørgensen, Chem. Commun. (1996) 2373–
2374;
(
6
(
(
g) H. Suga, X. Shi, H. Fujieda, T. Ibata, Tetrahedron Lett. 32 (1991) 6911–6914.
[
13] (a) Applications of aluminum TADDOLates as Lewis acids A.S. Timén, P.
Somfai, J. Org. Chem. 68 (2003) 9958–9963;
Acknowledgements
(
(
(
(
b) O. Corminboeuf, P. Reanaud, Org. Lett. 4 (2002) 1735–1738;
c) G. Manickam, G. Sundararajan, Tetrahedron 55 (1999) 2721–2736;
d) T. Ishikawa, K. Nagai, T. Kudoh, S. Saito, Synlett (1998) 1291–1293;
e) A.R. Fhal, P. Renaud, Tetrahedron Lett. 38 (1997) 2661–2664.
We are grateful to the Fonds der Chemischen Industrie for
financial support as well as for a Dozenten-Stipendium to B.G.
We also thank the Deutsche Forschungsgemeinschaft (DFG) for
support (GO-930-9). We are grateful to the Bayer A.G., the BASF
A.G., the Wacker A.G., the Degussa A.G., the Raschig GmbH, the Sol-
vay GmbH and the OMG AG for generous gifts of laboratory equip-
ments and chemicals.
[14] (a) T. Ooi, K. Marouka, Lewis Acids Org. Synth. 1 (2000) 191;
b) W.D. Wulff, Lewis Acids Org. Synth. 1 (2000) 283.
15] (a) E.F. Di Mauro, M.C. Kozlowski, Org. Lett. 3 (2001) 1641–1644;
b) G. Sundararajan, N. Prabagaran, Org. Lett. 3 (2001) 389–392;
(
[
[
(
(c) M.J. Jedrzegas, P. Setlow, Chem. Rev. 101 (2001) 607–618.
16] (a) M. Shibasaki, S. Matsunaga, J. Organomet. Chem. 691 (2006) 2089–2100;
(
(
b) M. Shibasaki, S. Matsunaga, Chem. Soc. Rev. 35 (2006) 269–279;
c) M. Kani, N. Kato, E. Ichikawa, M. Shibasaki, Pure Appl. Chem. 77 (2005)
References
2047–2052;
d) M. Shibasaki, N. Yoshikawa, Chem. Rev. 102 (2002) 2187–2210.
17] (a) D. Lange, J.-M. Neudörfl, B. Goldfuss, Tetrahedron 62 (2006) 3704–3709;
(
[
[
1] (a) B. Goldfuss, Synthesis (2005) 2271–2280;
(
(
(
(
(
b) F. Soki, J.-M. Neudörfl, B. Goldfuss, Tetrahedron 61 (2005) 10449–10453;
c) B. Goldfuss, T. Löschmann, F. Rominger, Chem. Eur. J. 7 (2001) 2028–2033;
d) B. Goldfuss, F. Rominger, Tetrahedron 56 (2000) 881–884;
e) B. Goldfuss, F. Eisenträger, Aust. J. Chem. 53 (2000) 209–212;
f) . For further fenchone and other terpene based ligand applications seeS.
(
(
b) B. Goldfuss, Top. Organomet. Chem. 5 (2003) 21–36;
c) D.M. Hodgson, Organolithiums in Enantioselective Synthesis, Top.
Organomet. Chem., vol. 5, Heidelberg, New York, 2003;
d) J. Clayden, Organolithiums: Selectivity for Synthesis, Tetrahedron Organic
Chemistry Series, vol. 23, Pergamon, Amsterdam, 2002;
e) A.-M. Sapse, P.von.R. Schleyer (Eds.), Lithium Chemistry, Wiley, New York,
995;
(
Panev, A. Linden, V. Dimitrov, Tetrahedron: Asymm. 12 (2001) 1313;
(
1
(
(
(
g) V. Dimitrov, A. Linden, M. Hesse, Tetrahedron: Asymm. 12 (2001) 1331;
h) V. Dimitrov, G. Dobrikov, M. Genov, Tetrahedron: Asymm. 12 (2001) 1323;
i) V. Dimitrov, G.H. Rentsch, A. Linden, M. Hesse, Helv. Chim. Acta 86 (2003)
(
(
(
f) C. Lambert, P.von.R. Schleyer, Angew. Chem. 106 (1994) 1187–1199;
g) C. Lambert, P.von R. Schleyer, Angew. Chem., Int. Ed. 33 (1994) 1129–1140;
h) C. Lambert, P.von R. Schleyer, Methoden Org. Chem., Houben Weyl, 4th ed.,
106.
[
[
18] (a) B. Goldfuss, M. Steigelmann, T. Löschmann, G. Schilling, F. Rominger,
Chem. Eur. J. 11 (2005) 4019–4023;
vol. E19d, 1952, Thieme, Stuttgart, 1993, p. 1;
i) W. Bauer, P.von R. Schleyer, in: V. Snieckus (Ed.), Advances in Carbanion
Chemistry, vol. 1, Jai Press, Greenwich, CT, 1992;
(
(
b) B. Goldfuss, M. Steigelmann, F. Rominger, H. Urtel, Chem. Eur. J. 7 (2001)
456–4464;
c) B. Goldfuss, M. Steigelmann, F. Rominger, Angew. Chem. 112 (2000) 4299–
302;
d) B. Goldfuss, M. Steigelmann, F. Rominger, Angew. Chem., Int. Ed. 39 (2000)
133–4136.
19] (a) M. Steigelmann, Y. Nisar, F. Rominger, B. Goldfuss, Chem. Eur. J. 8 (2002)
211–5218;
4
(
4
(
(
(
(
j) R. Noyori, M. Kitamura, Angew. Chem. 103 (1991) 34–55;
k) R. Noyori, M. Kitamura, Angew. Chem., Int. Ed. 30 (1991) 49–69;
l) J.F. Mc Garrity, C.A. Ogle, Z. Brich, H.-R. Loosli, J. Am. Chem. Soc. 107 (1985)
1
810–1815.
4
[
[
2] C.A. Musser, H.G. Richey Jr., J. Org. Chem. 65 (2000) 7750–7756.
3] (a) For amino alcohols as ligands S.C. Bergmeier, Tetrahedron 56 (2000) 2561–
5
2
576;
(
(
(
b) B. Goldfuss, M. Steigelmann, F. Rominger, Chem. Eur. J (2000) 1785–1792;
c) B. Goldfuss, M. Steigelmann, J. Mol. Mod. 6 (2000) 166–170;
d) B. Goldfuss, M. Steigelmann, S.I. Khan, K.N. Houk, J. Org. Chem. 65 (2000)
(
(
b) I. Sato, T. Saito, K. Soai, Chem. Commun. (2000) 2471–2472;
c) D.E. Frantz, R. Fässler, E.M. Carreira, J. Am. Chem. Soc. 122 (2000) 1806–
1
807;
7
7–82.
20] T. Kop-Weiershausen, J. Lex, J.-M. Neudörfl, B. Goldfuss, Beilstein J. Org. Chem.
(2005) 6–14.
(
(
(
(
(
d) M.R. Paleo, I. Cabeza, F.J. Sardina, J. Org. Chem. 65 (2000) 2108–2113;
e) W.A. Nugent, Chem. Commun. (1999) 1369–1370;
f) B. Goldfuss, K.N. Houk, J. Org. Chem. 63 (1998) 8998–9006;
g) P.I. Dosa, G.C. Fu, J. Am. Chem. Soc. 120 (1998) 445–446;
h) M. Kitamura, S. Suga, K. Kawai, R. Noyori, J. Am. Chem. Soc. 108 (1988)
[
[
1
21] (a) B. Goldfuss, T. Löschmann, T. Kop-Weiershausen, J.-M. Neudörfl, F.
Rominger, Beilstein J. Org. Chem. 2 (2006) 7–11;
(
(
b) B. Goldfuss, T. Löschmann, F. Rominger, Chem. Eur. J 10 (2004) 5422–5431;
c) J. Vàzquez, B. Goldfuss, G. Helmchen, J. Organomet. Chem. 641 (1-2) (2002)
6
071–6072.
[
4] (a) V.A. Pavlov, Russ. Chem. Rev. 73 (2004) 1173–1209;
6
(
7–70;
d) M. Kollmar, H. Steinhagen, J.P. Janssen, B. Goldfuss, S.A. Malinavskya, J.
Vàzquez, F. Rominger, G. Helmchen, Chem. Eur. J. 8 (2002) 3103–3114;
e) M. Kollmar, B. Goldfuss, M. Reggelin, F. Rominger, G. Helmchen, Chem. Eur.
J. 7 (2001) 4913–4927;
(
(
(
(
(
(
b) D.J. Ramon, M. Yus, Angew. Chem. 116 (2004) 286–289;
c) D.J. Ramon, M. Yus, Angew. Chem., Int. Ed. 43 (2004) 284–287;
d) B. Goldfuss, Nachr. Chem. 52 (2004) 281;
e) R. Noyori, S. Suga, H. Oka, M. Kitamura, Chem. Rec. 1 (2001) 85–100;
f) L. Pu, H.B. Yu, Chem. Rev. 101 (2001) 757–824;
(
(
f) B. Goldfuss, U. Kazmaier, Tetrahedron 56 (2000) 6493–6496.
g) K. Soai, T. Shibata, in: E.N. Jacobsen, A. Pfaltz, H. Yamamoto (Eds.),
0
[
22] The X-ray crystal structure of O-BIFOL (biphenylether-2,2 -bisfenchol) exhibits
intramolecular hydrogen bonds between the hydroxy groups of the fenchyl
moieties as well as between the oxygen atom of biphenylether and one
hydroxy group of the fenchyl residue.
Comprehensive Asymmetric Catalysis, Springer, Berlin, 1999, p. 911.
[
[
5] (a) J.S. You, S.-H. Hsieh, H.-M. Gau, Chem. Commun. (2001) 1546–1547;
(
(
(
(
b) J.-F. Lu, J.-S. You, H.-M. Gau, Tetrahedron Asymm. 1 (2000) 2531–2535;
c) B.L. Pagenkopf, E.M. Carreira, Tetrahedron Lett. 39 (1998) 9593–9596;
d) A.S.C. Chan, F.Y. Zhang, C.W. Yip, J. Am. Chem. Soc. 119 (1997) 4080–4081;
e) E.C. Ashby, S. Noding, J. Org. Chem. 44 (1979) 4792–4797.
[
23] (a) D. Seebach, A.K. Beck, A. Heckel, Essay Contemp. Chem. (2001) 283;
(
(
b) D. Seebach, A.K. Beck, A. Heckel, Angew. Chem. 113 (2001) 96–142;
c) D. Seebach, A.K. Beck, A. Heckel, Angew. Chem., Int. Ed. 40 (2001) 92–138.
6] (a) E.C. Ashby, J. Laemmle, H.M. Neumann, J. Am. Chem. Soc. 90 (1968) 5179–
188;
b) T. Mole, J.R. Surtees, Aust. J. Chem. 17 (1964) 961–966.
[
[
24] T.J. Boyle, D.M. Pedrotty, T.M. Alam, S.C. Vick, M.A. Rodriguez, Inorg. Chem. 39
2000) 5133–5146.
25] T. Arai, H. Sasai, K. Yamaguchi, M. Shibasaki, J. Am. Chem. Soc. 120 (1998) 441–
42.
26] H. Nöth, A. Schlegel, M. Suter, J. Organomet. Chem. 621 (2001) 231–241.
27] (a) A few structures with (AlO Li)-four-membered ring systems are known F.
5
(
(
[
[
7] The Cambridge Crystallographic Data Center (CCDC), 2006.
8] (a) K. Maruoka, T. Itoh, M. Sakurai, K. Nonoshita, H. Yamamoto, J. Am. Chem.
Soc. 110 (1988) 3588–3597;
4
[
[
(
b) M.B. Power, S.G. Bott, J.L. Atwood, A.R. Barron, J. Am. Chem. Soc. 112 (1990)
446–3451.
9] M.B. Power, S.G. Bott, D.L. Clark, J.L. Atwood, A.R. Barron, Organometallics 9
1990) 3086–3097.
2
Diedrich, U. Klingebiel, F. Dall’Antonia, C. Lehmann, M. Noltemeyer, T.R.
Schneider, Organometallics 19 (2000) 5376–5383;
3
[
(
b) W. Clegg, E. Lamb, S.T. Liddle, R. Snaith, A.E.H. Wheatley, J. Organomet.
Chem. 573 (1999) 305–312;
c) J. Storre, C. Schnitter, H.W. Roesky, H.G. Schmidt, M. Noltemeyer, R.
Fleischer, D. Stalke, J. Am. Chem. Soc. 119 (1997) 7505–7513.
(
[
[
10] A. Cottone III, M.J. Scott, Organometallics 21 (2002) 3610–3627.
11] (a) T. Ooi, M. Takahashi, M. Yamada, E. Tayama, K. Omoto, K. Marouka, J. Am.
Chem. Soc. 116 (2004) 1150–1160;
(

2
146
F. Soki et al. / Journal of Organometallic Chemistry 693 (2008) 2139–2146
[
28] (a) For short Li–H(C) distances, see B. Goldfuss, P.v.R. Schleyer, F. Hampel, J.
Am. Chem. Soc 118 (1996) 12183–12189;
(c) C.J. Harlan, S.G. Bott, A.R. Barron, J. Am. Chem. Soc. 117 (1995) 6465–
6474;
(
(
b) I. Hemme, B. Tecklenburg, M. Noltemeyer, U. Klingebiel, Chem. Ber. 128
1995) 351–355;
(d) T. Kottke, D. Stalke, Angew. Chem. 105 (1993) 619–621;
(e) T. Kottke, D. Stalke, Angew. Chem., Int. Ed. 32 (1993) 580–582.