Unexpected 1,5-dilithiation of chiral o-TMS blocked (dimethylamino) phenylmethylferrocene: An alternative approach to chiral ferrocenyl 1,5-diphosphanes

Article abstract of DOI:10.1021/jo062210l

(Chemical Equation Presented) The 1,5-dilithiation of o-TMS blocked (dimethylamino)phenylmethylferrocene 4 unexpectedly occurred even though one equimolar amount of t-BuLi was used and the 1,5-dilithiated ferrocene 6 was trapped by iodine followed by remo

Full text of DOI:10.1021/jo062210l

CHART 1. Chiral Ferrocenyl Diamine Ligands
Unexpected 1,5-Dilithiation of Chiral o-TMS
Blocked (Dimethylamino)phenylmethylferrocene:
An Alternative Approach to Chiral Ferrocenyl
1,5-Diphosphanes
Shin-ichi Fukuzawa,* Masahisa Yamamoto,
and Satoshi Kikuchi
Department of Applied Chemistry, Institute of Science and
Engineering, Chuo UniVersity, 1-13-27 Kasuga, Bunkyo-ku,
Tokyo 112-8551, Japan
SCHEME 1. Mono- and Dilithiations of Chiral Amino
Ferrocenes and Their Coupling Reaction by Fe(III)a
fukuzawa@kc.chuo-u.ac.jp
ReceiVed October 25, 2006
a Reagents: (a) t-BuLi (1.3 equiv), diethyl ether, 0 °C, 2 h. (b) Fe(acac)3
(1.6 equiv), 0 °C to rt, 22 h. (c) Ac2O; TMSN3/Cu(OTf)2 and then LiAlH4.
The 1,5-dilithiation of o-TMS blocked (dimethylamino)-
phenylmethylferrocene 4 unexpectedly occurred even though
one equimolar amount of t-BuLi was used and the 1,5-
dilithiated ferrocene 6 was trapped by iodine followed by
removal of the TMS group to give the 1,5-diiodoferrocene
11 in a reasonable yield. The 1,5-diiodoferrocene 11 was
converted into the diastereomer of Taniaphos 12 by sequen-
tial dilithiation and trapping with Ph2PCl. The rhodium and
copper complex of 12 catalyzed well the asymmetric allylic
alkylation with a Grignard reagent and hydrogenation with
the R-acetamidocinnamic acid ester, respectively, with high
enantioselectivities. The methoxy 1,5-diphosphane 14, of
which the enantiomer is known as a good ligand for the
rhodium-catalyzed asymmetric hydrogenation, was obtained
by the inversive substitution of the dimethylamino group of
11 by NaOMe and subsequent dilithiation and trapping with
Ph2PCl.
SCHEME 2. Known Method for the Synthesis of Taniaphos
tion to acetophenone; however, the enantiomeric excess of the
product was unsatisfactory (up to 55% ee). The low enantiose-
lectivity may be due to stereochemical mismatching of the planar
chirality and the central chirality of the amino carbon. We then
tried to prepare the bisferrocenyl diamine having a reverse planar
chirality to 2 by starting from the ortho-lithiation and the homo-
coupling of the o-TMS blocked ferrocene 4. Surprisingly, the
expected bisferrocene was not obtained, and the cyclized
ferrocene 7 was produced in 36% yield (Scheme 1). The product
was assumed to be the result of the intramolecular coupling of
the dilithio compound 6.3
We have been interested in the direct ortho-dilithiation of 4
and postulated that this reaction would be applied to the
synthesis of 1,5-diphosphane (i.e., the diastereomer of Tania-
phos);4 the original Taniaphos 9 bearing the (R,Sp) stereochem-
istry has been prepared via the 1,5-dilithiation of the ferrocene
having the o-bromoaryl group 8 as illustrated in Scheme 2 and
has recently been recognized as a useful ligand for metal
complex-catalyzed asymmetric reactions.5,6
We previously reported the preparation of the chiral 1,2-
ferrocenyl diamine 1 and asymmetric transfer hydrogenation
to ketones by its ruthenium complex.1 Although the enantiomeric
excess of the products was moderate (up to 75% ee), the
potential of the ferrocenyl diamine ligand was demonstrated.
We have prepared the bisferrocenyl diamine 2 by the sequence
of the homo-coupling of the o-lithio ferrocenyl amine 5
catalyzed by Fe(acac)3,2 the retentive substitution of the di-
methylamino group by the azide group, and reduction to the
primary amine (Scheme 1). The ruthenium complex of 2 and
its monotosylate could undergo asymmetric transfer hydrogena-
The 1,5-dilithiated ferrocene 6 was trapped by iodine to give
the 1,5-diiodide 10a, even though 1 equiv of t-BuLi and iodine
was used for 4; the yield of the diiodide was naturally low
* Corresponding author. Tel.: 81-3-3817-1916. Fax: 81-3-3817-1895.
(1) Fukuzawa, S.-i.; Suzuki, T. Eur. J. Org. Chem. 2006, 1012-1016.
(2) (a) Xiao, L.; Weissensteiner, W.; Mereiter, K.; Widhalm, M. J. Org.
Chem. 2002, 67, 2206-2214. Also see Supporting Information. (b) Spescha,
M.; Duffy, N. W.; Robinson, B. H.; Simpson, J. Organometallics 1994,
13, 4895-4904.
(3) Bringmann, G.; Hinrichs, J.; Peters, K.; Peters, E.-M. J. Org. Chem.
2001, 66, 629-632.
(4) (a) Ireland, T.; Grossheimann, G.; Wieser-Jeunesse, C.; Knochel, P.
Angew. Chem., Int. Ed. 1999, 38, 3212-3214. (b) Ireland, T.; Tappe, K.;
Grossheimann, G.; Knochel, P. Chem.sEur. J. 2002, 8, 843-852.
10.1021/jo062210l CCC: $37.00 © 2007 American Chemical Society
Published on Web 01/18/2007
1514
J. Org. Chem. 2007, 72, 1514-1517

SCHEME 3. Synthesis of dia-Taniaphosa
with inversion of the stereocenter of the methine carbon and
the subsequent lithiation and trapping with Ph2PCl in a good
yield.8 The enantiomer of 14 (i.e., (R,Sp)-14) has been prepared
by way of chromatographic separation of an almost 1:1
diastereomeric mixture of its precursor.9 It has been reported
that the ligand was used for their rhodium complex-catalyzed
asymmetric hydrogenation of alkenes with high enentioselec-
tivities. Our new method conveniently provides a facile way
for the preparation of the (S,Rp) isomer without separation of
the diastereomers.10
dia-Taniaphos 12 was applied for the copper-catalyzed allylic
alkylation of cinnamyl bromide 15 with a Grignard reagent5b,11
and the rhodium-catalyzed asymmetric hydrogenation of the
R-acetamidocinnamic acid ester 18.4,12 The reactions were
carried out according to the literature methods. In each reaction,
the product was obtained in high enantioselectivity (i.e., the
allylic alkylation (99% ee, S) and hydrogenation (96% ee, R)).
These results showed that 12 should be as efficient a ligand as
the original Taniaphos 9 for asymmetric reactions.
a Reagents: (a) t-BuLi (2.4 equiv) in diethyl ether, 0 °C, 2 h, then I2
(2.5 equiv) or BrCF2CF2Br (3 equiv). (b) t-BuOK (1.1 equiv) in DMSO,
rt, 15 h. (c) n-BuLi (2.4 equiv) in diethyl ether, 0 °C, 2 h, and then Ph2PCl
(2.2 equiv).
SCHEME 4. Synthesis of Methoxy 1,5-Diphosphanea
Experimental Section
Preparation of (Sp)-1-Trimethylsilyl-2-[(R)-1-(dimethylami-
no)phenylmethyl]ferrocene 4. In a 300 mL three-neck round-
bottomed flask containing a magnetic stirring bar were charged
[1-(R)-dimethylaminophenylmethyl]ferrocene 313 (>99% ee) (5.4
g, 17 mmol) and dry diethyl ether (60 mL) under a slight pressure
of nitrogen. The flask was cooled in an ice bath, and a hexane
solution of t-BuLi (1.6 M, 14 mL, 22 mmol) was then added using
a syringe through the septum with magnetic stirring. After 2 h,
trimethylsilyl chloride (2.8 g, 25.8 mmol) was injected into the
mixture at the same temperature. When the addition was completed,
the ice bath was removed, and the mixture was allowed to warm
to room temperature and stirred for an additional 15 h. The reaction
was quenched with water, and the solution was then extracted with
three 30 mL portions of diethyl ether. The combined extracts were
washed (brine), dried (K2CO3), and filtered, and the solvent was
removed on a rotary evaporator to leave a brown residue. The crude
product was purified by column chromatography on a silica gel
(hexane/ethyl acetate/triethyl amine ) 20:5:1) to give the pure 4
a Reagents: (a) NaOMe (1.1 equiv), CH3I (large excess) in methanol at
rt for 10 h. (b) t-BuLi (4.4 equiv) in THF, 0 °C, 2 h, and then Ph2PCl (2.2
equiv).
SCHEME 5. Representative dia-Taniaphos 12 Metal
Complex-Catalyzed Asymmetric Reactions
25
(40%), and the formation of the mono-iodoferrocene was not
observed in the 1H NMR spectrum of the reaction mixture; 60%
of unreacted 4 was recovered. When 2 molar equiv of t-BuLi
was used for 4, dilithiation adequately took place, and trapping
with more than 2 molar equiv of iodine afforded the diiodide
in 80% yield.7 The treatment of 10a with KOBut gave the TMS
free 11a in 84%. The 1,5-dilithiation of 11a followed by trapping
with 2 molar equiv of Ph2PCl gave the diphosphane (i.e., dia-
Taniaphos 12 bearing (R,Rp) stereochemistry) in 80% yield
(Scheme 3). Thus, starting from the original amino ferrocene
3, the dia-Taniaphos 12 was obtained in four steps in a 51%
overall yield.
as a brown oil. Yield, 6.3 g, 16.1 mmol, 95%. [R]D ) -98.4
1
(c ) 0.19, CHCl3). H NMR (CDCl3, 300 MHz) δ 0.49 (s, 9H),
2.14 (s, 6H), 3.77 (s, 5H), 4.12 (s, 1H), 4.16 (s, 1H), 4.42 (s, 1H),
4.56 (s, 1H), 7.37-7.64 (m, 5H); 13C NMR (CDCl3) δ 0.99, 43.4,
68.6, 68.8, 70.1, 70.8, 71.5, 73.1, 96.2, 126.8, 127.8, 128.5, 143.3.
(8) We are surprised at the inversion of the stereochemistry because it
has been reported that the displacement of a dimethylamino group in the
chiral ferrocenyl amine by the methoxide ion proceeds with retention. The
mechanism of the inversive dimethylaminophenylmethyl case may be
different from that of the retentive dimethylaminoethyl case. (a) Marquard-
ing, D.; Klusacek, H.; Gokel, G.; Hoffmann, P.; Ugi, I. J. Am. Chem. Soc.
1970, 92, 5389-5393. (b) Han, J. W.; Tokunaga, N.; Hayashi, T. HelV.
Chim. Acta. 2002, 85, 3848-3854.
(9) Lotz, M.; Polborn, K.; Knochel, P. Angew. Chem., Int. Ed. Engl.
2002, 41, 4708-4711.
(10) The preparative method for the (S,Sp)-methoxy Taniaphos without
separation has been reported recently while we were preparing this paper.
Chen, W.; Roberts, S. M.; Whittall, J.; Steiner, A. Chem. Commun. 2006,
2916-2918.
(11) For a review for the copper-catalyzed asymmetric allylic substitution,
see: (a) Yorimitsu, H.; Oshima, K. Angew. Chem., Int. Ed. 2005, 44, 4435-
4439. (b) Karlsto¨m, A. S. E.; Huerta, F. F.; Meuzelaar, G. J.; Ba¨ckvall,
J.-E. Synlett 2001, 923-926.
(12) For a review of asymmetric hydrogenation, see: Ohkuma, T.;
Kitamura, M.; Noyori, R. Asymmetric Hydrogenation, 2nd ed.; Ojima, I.,
Ed.; Wiley-VCH: New York, 2000; pp 1-110.
(13) (R)-3 was prepared by the reported method starting from CBS
reduction of benzoylferrocene.4a Fukuzawa, S.-i.; Fujimoto, K.; Komuro,
Y.; Matsuzawa, H. Org. Lett. 2002, 4, 707-709.
The methoxy 1,5-diphosphane (S,Rp)-14 could be prepared
by displacement of the dimethylamino group of 11b by NaOMe
(5) (a) Lo´pez, F.; Harutyunyan, S. R.; Minnaard, A. J.; Feringa, B. L.
J. Am. Chem. Soc. 2004, 126, 12784-12785. (b) Lo´pez, F.; van Zijl, A.
W.; Minnaard, A. J; Feringa, B. L. Chem. Commun. 2006, 409-411. (c)
Godard, C.; Ruiz, A.; Claver, C. HelV. Chim. Acta 2006, 89, 1610-1622.
(d) Oisaki, K.; Zhao, D.; Kanai, M.; Shibasaki, M. J. Am. Chem. Soc. 2006,
128, 7164-7165. (e) Zhao, D.; Oisaki, K.; Kanai, M.; Shibasaki, M.
J. Am. Chem. Soc. 2006, 128, 14440-14441.
(6) For a review of ferrocenyl phosphines in asymmetric synthesis, see:
Colacot, T. J. Chem. ReV. 2003, 103, 3101-3118.
(7) Treatment of (R)-3 with 2 equiv of t-BuLi followed by trapping with
an excess of BrCF2CF2Br gave 93% of the corresponding (R,Sp)-mono
bromide together with 7% of the 1,5-dibromide.
J. Org. Chem, Vol. 72, No. 4, 2007 1515

Anal. calcd for C22H29FeNSi: C, 67.51; H, 7.47; N, 3.58. Found:
C, 67.37; H, 7.64; N, 3.22.
Preparation of (Rp)-1-Diphenylphosphanyl-2-[(R)-1-(di-
methylamino)-o-diphenylphosphanylphenylmethyl]ferrocene 12;
dia-Taniaphos. In a 50 mL Schlenk tube containing a magnetic
stirring bar were charged 11a (1.10 g, 1.93 mmol) and dry diethyl
ether (60 mL) under a slight pressure of nitrogen. The flask was
cooled in an ice bath, and a hexane solution of n-BuLi (1.6 M, 2.9
mL, 4.6 mmol) was then added using a syringe through the septum
with magnetic stirring. After 2 h, Ph2PCl (0.9 mL, 4.8 mmol) was
injected into the mixture at the same temperature. When the addition
was completed, the ice bath was removed, and the mixture was
allowed to warm to room temperature and stirred for an additional
5 h. The reaction was quenched with water, and the solution was
then extracted with three 30 mL portions of dichloromethane. The
combined extracts were washed (brine), dried (MgSO4), and filtered,
and the solvent was removed on a rotary evaporator to leave a
brown residue. The crude product was purified by column chro-
matography on silica gel (hexane/diethyl ether/triethyl amine ) 20:
2:1) to give pure 12 as a yellow solid. Yield, 1.06 g, 1.54 mmol,
80%. Mp ) 68 °C. [R]D ) +260 (c ) 0.50, CHCl3). H NMR
(CDCl3, 300 MHz) δ 2.10 (s, 6H), 3.90 (s, 5H), 3.96 (s, 1H), 4.37
(s, 1H), 4.61 (s, 1H), 6.08 (d, 1H, J ) 7.5 Hz), 6.8-7.6 (m, 24H,
aromatic signals); 13C NMR (CDCl3) δ 43.4, 68.8, 70.3, 71.4, 71.7,
73.4, 98.8, 126.6-139.6 (several aromatic signals), 147.4; 31P NMR
(CDCl3) δ -18.6 (J ) 16.2 Hz), -25.1 (J ) 16.2 Hz). Anal. calcd
for C43H39FeNP2: C, 75.11; H, 5.72; N, 2.04. Found: C, 74.94;
H, 5.77; N, 2.08. Crystals suitable for the X-ray analysis were
obtained by recrystallization from CHCl3-hexane. CCDC 624117.
Preparation of (Rp)-3-Iodo-(Sp)-1-trimethylsilyl-2-[(R)-1-
(dimethylamino)-o-iodophenylmethyl]ferrocene 10a. In a 300 mL
three-neck round-bottomed flask containing a magnetic stirring bar
were charged 4 (5.9 g, 15.1 mmol) and dry diethyl ether (60 mL)
under a slight pressure of nitrogen. The flask was cooled in an ice
bath, and a hexane solution of t-BuLi (1.6 M, 22.5 mL, 36 mmol)
was then added using a syringe through the septum with magnetic
stirring. After 2 h, a THF (40 mL) solution of iodine (9.6 g, 38
mmol) was injected into the mixture at the same temperature. When
the addition was completed, the ice bath was removed, and the
mixture was allowed to warm to room temperature and then stirred
for an additional 15 h. The reaction was quenched with aqueous
Na2S2O3, and the solution was then extracted with three 30 mL
portions of diethyl ether. The combined extracts were washed
(brine), dried (K2CO3), and filtered, and the solvent was removed
on a rotary evaporator to leave a brown residue. The crude product
was purified by column chromatography on silica gel (hexane/
diethyl ether/triethyl amine ) 20:1:1) to give the pure 10a as a
reddish brown solid. Yield, 7.70 g, 12.1 mmol, 80%. Mp ) 85 °C.
25
1
25
1
[R]D ) +24.4 (c ) 0.50, CHCl3). H NMR (CDCl3, 300 MHz)
δ 0.26 (s, 9H), 2.51 (s, 6H), 4.19 (s, 5H), 4.30 (s, 1H), 4.55 (s,
1H), 5.00 (s, 1H), 6.58 (d, 1H, J ) 7.5 Hz), 6.83 (t, 1H, J ) 7.3
Hz), 7.09 (t, 1H, J ) 7.5 Hz), 7.81 (d, 1H, J ) 7.8 Hz); 13C NMR
(CDCl3) δ 1.6, 45.2, 69.8, 72.1, 72.6, 75.4, 77.7, 97.8, 105.8, 127.8,
128.5, 131.3, 139.0, 144.2. Anal. calcd for C22H27FeI2NSi: C, 41.08;
H, 4.23; N, 2.18. Found: C, 39.86; H, 4.25; N, 2.03.
Preparation of (Rp)-1-Bromo-2-[(S)-1-methoxy-o-bromophe-
nylmethyl]ferrocene 13. In a 100 mL three-neck round-bottomed
flask containing a magnetic stirring bar were charged 11b (0.87 g,
1.82 mmol) and dry MeOH (10 mL) under a slight pressure of
nitrogen. To the flask were successively added MeONa (0.110 g,
2.0 mmol) and a methanol solution of MeI (10.0 g, 70 mmol), and
then the resulting mixture was stirred at room temperature for 15
h. The reaction was quenched with diluted HCl, and the solution
was extracted with three 30 mL portions of dichloromethane. The
combined extracts were washed (brine), dried (MgSO4), and filtered,
and the solvent was removed on a rotary evaporator to leave a
brown residue. The crude product was purified by column chro-
matography on silica gel (hexane/diethyl ether ) 20:1) to give pure
13 as a yellow oil. Yield, 0.53 g, 1.14 mmol, 63%. [R]D25 ) +80.0
(Rp)-3-Bromo-(Sp)-1-trimethylsilyl-2-[(R)-1-(dimethylamino)-o-
bromophenylmethyl]ferrocene 10b was similarly prepared by the
previous procedure using BrCF2CF2Br instead of I2: Yellow solid,
Mp ) 118 °C. [R]D25 ) +65.0 (c ) 0.20, CHCl3). 1H NMR (CDCl3,
300 MHz) δ 0.30 (s, 9H), 2.38 (s, 6H), 4.17 (s, 5H), 4.19 (s, 1H),
4.55 (s, 1H), 5.21 (s, 1H), 7.00 (d, 1H, J ) 7.7 Hz), 7.03 (t, 1H,
J ) 7.9. Hz), 7.12 (t, 1H, J ) 7.5 Hz), 7.55 (dd, 1H, J ) 7.9 Hz);
13C NMR (CDCl3) δ 1.6, 44.5, 67.3, 69.9, 71.6, 72.7, 73.3, 80.0,
94.5, 126.6, 126.8, 128.3, 131.9, 132.2, 140.6. Anal. calcd for
C22H27Br2FeNSi: C, 48.11; H, 4.96; N, 2.55; Found: C, 48.08; H,
4.83; N, 2.18.
Preparation of (Rp)-1-Iodo-2-[(R)-1-(dimethylamino)-o-io-
dophenylmethyl]ferrocene 11a. In a 300 mL round-bottomed flask
containing a magnetic stirring bar were charged 10a (3.5 g, 5.44
mmol) and dry DMSO (70 mL) under a slight pressure of nitrogen.
The flask was cooled in an ice bath, t-BuOK (0.66 g, 5.9 mmol)
was added, and the mixture was then stirred at 0 °C for 1 h followed
by stirring at room temperature for an additional 15 h. The reaction
was quenched with water, and the solution was extracted with three
30 mL portions of dichloromethane. The combined extracts were
washed (brine), dried (MgSO4), and filtered, and the solvent was
removed on a rotary evaporator to leave a brown residue. The crude
product was purified by column chromatography on silica gel
(hexane/diethyl ether/triethyl amine ) 20:1:1) to give pure 11a as
1
(c ) 0.21, CHCl3). H NMR (CDCl3, 300 MHz) δ 3.23 (s, 3H),
3.98 (s, 5H), 4.10 (dd, 1H, J ) 1.4, 2.7 Hz), 4.15 (t, 1H, J ) 2.6
Hz), 4.50 (d, 1H, J ) 1.5, 2.2 Hz), 5.77 (s, 1H), 7.25 (dt, 1H, J )
1.7, 7.7 Hz), 7.42 (t, 1H, J ) 7.4 Hz), 7.67 (t, 1H, J ) 7.0 Hz),
7.68 (t, 1H, J ) 7.7 Hz); 13C NMR (CDCl3) δ 56.8, 65.2, 66.9,
70.4, 71.2, 78.7, 79.8, 86.0, 124.0, 127.5, 129.1, 129.4, 132.7, 140.2.
Anal. calcd for C18H16FeBr2O: C, 46.60; H, 3.48. Found: C, 46.75;
H, 3.83.
Preparation of (Rp)-1-(Diphenylphosphanyl-2-[(S)-1-methoxy-
o-diphenylphosphanylphenylmethyl]ferrocene 14. In a 50 mL
Schlenk tube containing a magnetic stirring bar were charged 13
(0.45 g, 0.97 mmol) and dry THF (10 mL) under a slight pressure
of nitrogen. The flask was cooled in a dry ice bath, and a hexane
solution of t-BuLi (1.6 M, 2.7 mL, 4.3 mmol) was then added using
a syringe through the septum with magnetic stirring. After 20 min,
Ph2PCl (0.39 mL, 2.1 mmol) was injected into the mixture at
-78 °C and stirred for 2 h. When the addition was completed, the
dry ice bath was removed, and the mixture was allowed to warm
to room temperature and then stirred for an additional 15 h. The
reaction was quenched with saturated NaHCO3, and the solution
was then extracted with three 30 mL portions of dichloromethane.
The combined extracts were washed (brine), dried (MgSO4), and
filtered, and the solvent was removed on a rotary evaporator to
leave a yellow residue. The crude product was purified by column
chromatography on silica gel (hexane/diethyl ether ) 20:1) to give
pure 14 as a yellow solid. Yield, 0.52 g, 0.77 mmol, 80%. Mp )
25
a yellow solid. Yield, 2.60 g, 4.55 mmol, 84%. Mp ) 89 °C. [R]D
1
) +77.0 (c ) 0.50, CHCl3). H NMR (CDCl3, 300 MHz) δ 2.48
(s, 6H), 4.12 (s, 5H), 4.26 (s, 1H), 4.40 (s, 1H), 4.55(s, 1H), 4.90
(s, 1H), 6.89 (t, 1H, J ) 7.2 Hz), 7.00 (d, 1H, J ) 7.6 Hz), 7.20
(t, 1H, J ) 7.5 Hz), 7.85 (d, 1H, J ) 7.8 Hz); 13C NMR (CDCl3)
δ 44.2, 67.6, 68.4, 72.0, 72.1, 75.0, 92.1, 104.7, 127.8, 128.5, 130.6,
139.1, 143.7. Anal. calcd for C19H19FeI2N: C, 39.96; H, 3.35; N,
2.45. Found: C, 40.21; H, 3.13; N, 2.42.
(Rp)-1-Bromo-2-[(R)-1-(dimethylamino)-o-bromophenylmethyl]-
25
ferrocene 11b: Mp ) 87 °C. [R]D ) +126 (c ) 0.20, CHCl3).
1H NMR (CDCl3, 300 MHz) δ 2.44 (s, 6H), 4.13 (s, 5H), 4.18 (s,
1H), 4.37 (t, 1H, J ) 2.0 Hz), 5.02 (s, 1H), 7.05-7.21 (m, 3H),
7.57 (d, 1H, J ) 7.6 Hz); 13C NMR (CDCl3) δ 44.5, 65.3, 67.1,
67.5, 70.3, 71.7, 77.2, 90.1, 126.1, 127.1, 128.3, 130.9, 132.3, 141.0.
Anal. calcd for C19H19Br2FeN: C, 47.84; H, 4.01; N, 2.94. Found:
C, 47.92; H, 3.95; N, 2.85.
25
1
66 °C. [R]D ) +247 (c ) 0.10, CHCl3). H NMR (CDCl3, 300
1516 J. Org. Chem., Vol. 72, No. 4, 2007

MHz) δ 2.32 (s, 3H), 3.78 (s, 1H), 3.81 (s, 5H), 4.25 (t, 1H, J )
2.6 Hz), 4.32 (s, 1H), 6.12 (dd, 1H, J ) 5.1 Hz), 7.1-7.7 (m, 24H);
13C NMR (CDCl3) δ 55.8, 69.3, 69.6, 70.0, 71.5, 76.7, 94.7, 95.1,
125-145 (several aromatic signals); 31P NMR (CDCl3) δ -16.3
(J ) 16.7 Hz), -21.8 (J ) 16.7 Hz). Anal. calcd for C42H36-
FeOP2: C, 74.79; H, 5.38. Found: C, 75.11; H, 5.55.
a Grant-in-Aid, 16550044, for Scientific Research from the
Japan Society for the Promotion of Science (JSPS).
Supporting Information Available: Experimental details for
the preparation of compounds 2, 7, and related compounds including
their 1H and 13C NMR spectra (PDF); the 1H and 13C NMR spectra
of the ferrocene compounds 4 and 10-14 (PDF); and crystal-
lographic data in CIF files for 7 and 12. Experimental procedures
for the metal complex-catalyzed asymmetric reactions using 12 as
a ligand. This material is available free of charge via the Internet
at http://pubs.acs.org.
Acknowledgment. We thank Prof. Youichi Ishii and Dr.
Yoshiaki Tanabe, Department of Applied Chemistry, Chuo
University, for the X-ray diffraction analysis of the chiral
ferrocene compounds. This study was financially supported by
JO062210L
J. Org. Chem, Vol. 72, No. 4, 2007 1517