Chiral sterically congested phosphane-amide bifunctional organocatalysts in asymmetric aza-Morita-Baylis-Hillman reactions of N-sulfonated imines with methyl and ethyl vinyl ketones

Article abstract of DOI:10.1002/ejoc.200800050

A series of chiral sterically congested phosphane-amide bifunctional Lewis bases L1-L3 have been successfully synthesized and their application in asymmetric aza-Morita-Baylis-Hillman (aza-MBH) reactions of N-sulfonated imines with activated olefins such

Full text of DOI:10.1002/ejoc.200800050

FULL PAPER
DOI: 10.1002/ejoc.200800050
Chiral Sterically Congested Phosphane-Amide Bifunctional Organocatalysts in
Asymmetric Aza-Morita–Baylis–Hillman Reactions of N-Sulfonated Imines
with Methyl and Ethyl Vinyl Ketones
Xiao-Yang Guan,[a] Ying-Qing Jiang,[a] and Min Shi*[a]
Keywords: Morita–Baylis–Hillman reactions / Asymmetric catalysis / Alkenes / Imines / Organocatalysis
A series of chiral sterically congested phosphane-amide bi-
yields (up to 98%) and moderate-to-good enantioselectivities
functional Lewis bases L1–L3 have been successfully synthe- (up to 91 or 93% ee) in dichloromethane at room temperature
sized and their application in asymmetric aza-Morita–Baylis–
Hillman (aza-MBH) reactions of N-sulfonated imines with ac-
tivated olefins such as methyl and ethyl vinyl ketone has
been investigated under mild conditions. The corresponding
aza-MBH adducts can be obtained in good-to-excellent
(20 °C) with these novel chiral bifunctional phosphane Lewis
bases.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
Introduction
catalytic asymmetric versions of these reactions and several
excellent multifunctional organocatalysts for the aza-MBH
The asymmetric Morita–Baylis–Hillman (MBH) and reaction have been reported to achieve high enantio-
aza-Morita–Baylis–Hillman (aza-MBH) reactions are two selectivities.[2] Among these successful chiral bifunctional
of the most useful and interesting carbon–carbon bond- organocatalysts, axially chiral 1,1Ј-binaphthalene-derived
forming reactions, respectively giving enantiomerically en- bifunctional phosphanes developed by us, Sasai and others
riched β-hydroxy or β-amino carbonyl compounds bearing have shown excellent chiral induction abilities for the aza-
an α-alkylidene group which have enormous potential syn- MBH reaction (Figure 1).[2b,2e,2h,2k,2m,2n,2p,2s] As the devel-
thetic utility under mild reaction conditions.[1] Over the last opment of new and more efficient chiral bifunctional phos-
decade, great progress has been made in the development of phanes is the main target in asymmetric MBH or aza-MBH
Figure 1. Some representative BINOL-derived bifunctional phosphanes for the aza-Morita–Baylis–Hillman reaction.
catalytic reactions, we have been continuing to develop such
[a] State Key Laboratory of Organometallic Chemistry, Shanghai
novel chiral bifunctional phosphanes for use in asymmetric
Institute of Organic Chemistry, Chinese Academy of Sciences,
MBH[3] and aza-MBH reactions. In this paper, we wish to
Shanghai 200032, China
Fax: +86-21-64166128
report the synthesis of novel chiral sterically congested
phosphane-amide bifunctional organocatalysts L1, L2 and
L3 and their application in asymmetric aza-MBH reactions.
E-mail: mshi@mail.sioc.ac.cn
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
2150
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 2150–2155

Asymmetric Aza-Morita–Baylis–Hillman Reactions
ture (20 °C) or at a lower temperature. The results of these
experiments are summarized in Tables 1, 2, and 3, respec-
Results and Discussion
The synthetic route for the preparation of chiral sterically tively. As can be seen from Table 1, when the asymmetric
congested bifunctional phosphane-amide Lewis bases L1, aza-MBH reaction was carried out in dichloromethane
L2 and L3 is straightforward and is clearly shown in (DCM), acetonitrile (MeCN), dimethyl sulfoxide (DMSO),
Scheme 1. Treating (R)-2Ј-diphenylphosphanyl-1,1Ј-binaph- toluene (PhMe) or tetrahydrofuran (THF) at room tem-
thyl-2-ylamine[4] with terephthaloyl dichloride, isophthaloyl perature (20 °C), the reactions proceeded smoothly to give
dichloride and 1,3,5-benzenetricarbonyl trichloride af- the corresponding adduct 2a in good yields and moderate
forded the corresponding sterically congested chiral bifunc- enantiomeric excesses (up to 93% yield and 73% ee) in the
tional phosphane-amide Lewis bases L1, L2 and L3 in good presence of L1 (10 mol-%), although no ee was observed in
yields in dichloromethane at room temperature in the pres- DMSO (Table 1, entries 1 and 3–6). Notably, the ee of 2a
ence of potassium carbonate, respectively. The synthetic could be further improved to 80% with 90% yield at 0 °C
procedures are quite simple and detailed experimental pro- in DCM after 45 h under otherwise identical conditions
cedures and the corresponding spectroscopic data are re- (Table 1, entry 2). It also should be emphasized here that at
ported in the Supporting Information.[5]
–10 °C, the reaction became sluggish, giving 2a in low yield.
To investigate the catalytic activities of these novel chiral Thus, the best results are obtained under these reaction
sterically congested phosphane-amide bifunctional Lewis conditions at 0 °C when using L1 as the chiral organocata-
bases in asymmetric aza-MBH reactions, an initial exami- lyst in this asymmetric aza-MBH reaction. With chiral steri-
nation was carried out by using N-benzylidene-4-methyl- cally congested phosphane-amide bifunctional phosphane
benzenesulfonamide (1a) or N-(p-chlorobenzylidene)-4- L2, examination of solvent effects and reaction tempera-
methylbenzenesulfonamide (1c) and methyl vinyl ketone tures revealed that the reaction should be carried out in
(MVK) as the substrates in the presence of 10 mol-% of DCM at room temperature (20 °C) for 24 h (Table 2, en-
chiral Lewis bases L1, L2 or L3 (6.7 mol-% similar P atom tries 3 and 4). Under these conditions, the corresponding
mol-% as L1 and L2) in various solvents at room tempera- adduct 2c was obtained in 98% yield and 84% ee. At –10
Scheme 1. Synthesis of chiral bifunctional phosphane-amide Lewis bases L1–L3.
Eur. J. Org. Chem. 2008, 2150–2155
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2151

X.-Y. Guan, Y.-Q. Jiang, M. Shi
FULL PAPER
and 0 °C, 2c was formed in yields of 72% and with 82 and Table 2. Asymmetric aza-Morita–Baylis–Hillman reactions of N-
(p-chlorobenzylidene)-4-methylbenzenesulfonamide (1c) (1.0 equiv.)
77% ee values in DCM, respectively (Table 2, entries 1 and
2). Other solvents were not as effective as DCM with L2 as
with methyl vinyl ketone (MVK) (2.0 equiv.) in the presence of L2
(10 mol-%).
organocatalyst at room temperature (20 °C). With bifunc-
tional phosphane-amide organocatalyst L3 (6.7 mol-%), the
reaction conditions were optimized in a similar way to that
described above. The results of these experiments are sum-
marized in Table 3. The aza-MBH reaction of 1c with
MVK afforded the corresponding adduct 2c in 87% yield
and 93% ee after 90 h at –10 °C as well as in 98% yield and
91% ee after 24 h at room temperature (20 °C) in DCM,
which indicates that the more sterically congested phos-
phane-amide bifunctional Lewis base L3 could also facili-
tate chiral induction in asymmetric aza-MBH reaction
(Table 3, entries 1 and 2). Other solvents were not as effec-
tive as DCM with L3 (6.7 mol-%) as organocatalyst under
otherwise identical conditions (Table 3, entries 4–6). There-
fore, if using L3 (6.7 mol-%) as the chiral Lewis base in aza-
MBH reactions in DCM, the reactions should be carried
out at room temperature (20 °C) at the expense of around
2% ee because of the much reduced reaction time. It should
be emphasized here that the corresponding aza-MBH ad-
ducts 2 are all obtained in the S configuration in all of the
above cases.
Entry
Solvent
Temp.
[°C]
Time
[h]
Yield[a]
[%]
ee[b]
[%]
Absolute
configuration[c]
1
2
3
4
5
6
7
DCM
DCM
DCM
DCM
PhMe
DCE
–10
0
90
24
24
10
24
24
24
72
72
98
48
63
61
37
82
77
84
84
74
84
50
S
S
S
S
S
S
S
r.t.
r.t.
r.t.
r.t.
r.t.
MeCN
[a] Isolated yields. [b] Determined by HPLC with a chiral column.
[c] Determined by the sign of the specific rotation.
Table 3. Aza-Morita–Baylis–Hillman reactions of N-(p-chloro-
benzylidene)-4-methylbenzenesulfonamide (1c) (1.0 equiv.) with
methyl vinyl ketone (MVK) (2.0 equiv.) in the presence of L3
(6.7 mol-%).
Table 1. Screening of solvents and temperatures for the asymmetric
aza-MBH reaction of N-benzylidene-4-methylbenzenesulfonamide
(1a) (1.0 equiv.) with methyl vinyl ketone (MVK) (2.0 equiv.) cata-
lysed by L1 (10 mol-%).
Entry
Solvent
Temp.
[°C]
Time
[h]
Yield[a]
[%]
ee[b]
[%]
Absolute
configuration[c]
1
2
3
4
5
6
DCM
DCM
DCM
PhMe
DCE
–10
r.t.
r.t.
r.t.
r.t.
r.t.
90
24
10
24
24
24
87
98
66
55
81
52
93
91
90
80
91
73
S
S
S
S
S
S
Entry Solvent
Temp.
[°C]
Time
[h]
Yield[a]
[%]
ee[b]
[%]
Absolute
configuration[c]
1
2
3
4
5
6
DCM
DCM
MeCN
DMSO
PhMe
THF
20
0
20
20
20
20
10
45
52
32
45
66
88
90
66
73
93
79
73
80
65
0
65
70
S
S
S
S
S
S
MeCN
[a] Isolated yields. [b] Determined by HPLC with a chiral column.
[c] Determined by the sign of the specific rotation.
[a] Isolated yields. [b] Determined by HPLC with a chiral column.
[c] Determined by the sign of the specific rotation.
With the optimal reaction conditions identified, we next
turned our attention to examining the scope of these cata-
The control experiments outlined in Scheme 1 indicated lytic, asymmetric aza-MBH reactions using a variety of N-
that the chiral sterically congested phosphane-amide bi- sulfonated imines with MVK or ethyl vinyl ketone (EVK).
functional phosphanes L2 and L3 are indeed more effective We found that when L1 was utilized as the catalyst, the
than the original chiral bifunctional phosphane-amide L4 corresponding aza-MBH reaction adducts 2b–2g were ob-
[(R)-N-(2Ј-diphenylphosphanyl-1,1Ј-binaphthyl-2-yl)benza-
tained in moderate-to-good ee values (up to 87%) along
mide] (20 mol-%) because when L4 (20 mol-%) was used as with good-to-high yields at room temperature (20 °C), irre-
catalyst,[6] the corresponding adduct 2c was formed in 84% spective of whether the imines 1 have electron-withdrawing
yield and 78% ee under identical conditions (Scheme 2). or -donating groups on the benzene substituent (Table 4,
Moreover, (2Ј-diphenylphosphanyl-1,1Ј-binaphthyl-2-yl)di- entries 1–6). In addition, the range of N-sulfonated imines
methylamine (L5, 20 mol-%) did not catalyse this reaction that can be used with L2 (10 mol-%) and L3 (6.7 mol-%) as
under the standard conditions,[6] which suggests that an the organocatalyst in the aza-MBH reactions has also been
active amide proton in the catalyst is crucial for this asym- examined and the results are shown in Table 5. The data
metric catalytic process and chiral phosphanes L1–L4 are show that L3 is more effective than L2 under optimal con-
LB (Lewis base) and BA (Brønsted acid) bifunctional phos- ditions, giving the corresponding adducts 2 in higher ee val-
phane Lewis bases (Scheme 1).2b,2e
ues [up to 91% ee for N-(p-nitrobenzylidene)-4-methylben-
2152
www.eurjoc.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 2150–2155

Asymmetric Aza-Morita–Baylis–Hillman Reactions
Scheme 2. Control experiments in the aza-Morita–Baylis–Hillman reaction.
zenesulfonamide (1h)] and similar chemical yields (Table 5,
entries 1–4). Therefore, we used L3 (6.7 mol-%) as the or-
ganocatalyst to examine the reactions of other N-sulfonated
imines with MVK and EVK. The results of these experi-
ments are outlined in Table 6. The corresponding adducts
2d,f,g, 2i–k and 3a,b were obtained in moderate-to-good
yields and ee values (Table 6, entries 1–8). With the ortho-
substituted N-sulfonated imines 1j and 1k, the correspond-
ing adducts were formed in lower ee values, which suggests
that these chiral sterically congested phosphane-amide bi-
functional phosphanes are not suitable for use in asymmet-
ric aza-MBH reactions with sterically hindered N-sulfo-
nated imines (Table 6, entries 5 and 6).
Table 5. Asymmetric aza-Morita–Baylis–Hillman reactions of N-
(arylmethylidene)arylsulfonamides (1.0 equiv.) with methyl vinyl
ketone (MVK) (2.0 equiv.) in the presence of L2 (10 mol-%) or L3
(6.7 mol-%).
Entry Ar
Yield with
ee with
Absolute
L2/L3[a] [%]
L2/L3[b] [%] configuration[c]
1
2
3
4
C6H5 (1a)
2a, 83/73
2b, 82/79
2e, 60/64
2h, 79/81
64/79
80/81
79/85
82/91
S
S
S
S
p-MeC6H4 (1b)
m-NO2C6H4 (1e)
p-NO2C6H4 (1h)
Table 4. Asymmetric aza-MBH reactions of N-(arylmethylidene)ar-
ylsulfonamides (1.0 equiv.) with methyl vinyl ketone (MVK)
(2.0 equiv.) catalysed by L1 (10 mol-%).
[a] Isolated yields. [b] Determined by HPLC with a chiral column.
[c] Determined by the sign of the specific rotation.
Table 6. Asymmetric aza-Morita–Baylis–Hillman reactions of N-
(arylmethylidene)arylsulfonamides (1.0 equiv.) with methyl vinyl
ketone (MVK) or ethyl vinyl ketone (EVK) (2.0 equiv.) in the pres-
ence of L3 (6.7 mol-%).
Entry
R
Time
[h]
Yield[a]
[%]
ee[b]
[%]
Absolute
configuration[c]
1
2
3
4
5
6
p-MeC6H4 (1b)
p-ClC6H4 (1c)
p-BrC6H4 (1d)
m-NO2C6H4 (1e)
m-ClC6H4 (1f)
m-FC6H4 (1g)
48
23
24
27
24
24
2b, 84
2c, 98
2d, 89
2e, 82
2f, 73
2g, 72
77
87
79
68
70
70
S
S
S
S
S
S
Entry
Ar
R
Yield[a]
[%]
ee[b]
[%]
Absolute
configuration[c]
1
2
3
4
5
6
7
8
p-BrC6H4 (1d)
m-ClC6H4 (1f)
m-FC6H4 (1g)
p-FC6H4 (1i)
o-ClC6H4 (1j)
o-BrC6H4 (1k)
p-ClC6H4 (1c)
p-BrC6H4 (1d)
Me
Me
Me
Me
Me
Me
Et
2d, 83
2f, 87
2g, 92
2i, 89
2j, 77
2k, 73
3a, 80
3b, 69
87
86
84
85
50
35
85
80
S
S
S
S
S
S
S
S
[a] Isolated yields. [b] Determined by HPLC with a chiral column.
[c] Determined by the sign of the specific rotation.
To compare our original chiral phosphane Lewis base
(R)-2Ј-diphenylphosphanyl-1,1Ј-binaphthyl-2-ol [(R)-L6],
aza-MBH reactions using (R)-L6 as organocatalyst under
similar conditions were carried out and the results are
Et
[a] Isolated yields. [b] Determined by HPLC with a chiral column.
shown in Table 7.[2b,2e] As can be clearly seen, the chiral [c] Determined by the sign of the specific rotation.
Eur. J. Org. Chem. 2008, 2150–2155
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2153

X.-Y. Guan, Y.-Q. Jiang, M. Shi
FULL PAPER
nigan MA+ mass spectrometer. Infrared spectra were measured
with a Perkin–Elmer 983 spectrometer. Melting points were ob-
tained with a Yanagimoto micromelting point apparatus and are
uncorrected. N-Sulfonated imines 1 were prepared according to the
literature. Commercial reagents were used without further purifica-
tion. All reactions were monitored by TLC on Huanghai GF254
silica gel coated plates. Flash column chromatography was carried
out at increased pressure using 200–300 mesh silica gel. The optical
purities of the aza-Morita–Baylis–Hillman adducts were deter-
mined by HPLC analysis using a chiral stationary phase column
(column, Daicel Co. Chiralcel AD, AS, TBB and OJ; eluent: hex-
ane/2-propanol; flow rate, 0.7 mLmin–1; detection: 254 or 220 nm
light) and the absolute configurations of the major enantiomers
were assigned according to the sign of the specific rotation.
sterically congested phosphane-amide bifunctional Lewis
bases L1, L2 and L3 have similar chiral induction abilities
at room temperature (20 °C) in DCM as our original chiral
phosphane Lewis base (R)-L6 at –30 °C in THF under the
standard conditions. Therefore, we believe that these chiral
phosphane-amide bifunctional Lewis bases may have prac-
tical use in asymmetric aza-MBH reactions as the reaction
can be carried out at 0 °C or room temperature (20 °C) to
give the products in good yields and ee values.
Table 7. Asymmetric aza-Morita–Baylis–Hillman reactions of N-
(arylmethylidene)arylsulfonamide 1 (1.0 equiv.) with methyl vinyl
ketone (3.0 equiv.) in the presence of chiral phosphane Lewis base
(R)-L6 (10 mol-%).
Typical Reaction Procedure for L3-Catalysed Aza-Morita–Baylis–
Hillman Reaction of N-Sulfonated Imines with MVK: A 10 mL
Schlenk tube containing N-(p-chlorobenzylidene)-4-methylben-
zenesulfonamide (1c) (37 mg, 0.125 mmol) and L3 (13 mg.
0.0086 mmol) was degassed and the reaction vessel was protected
under argon. Then DCM (1.0 mL) and methyl vinyl ketone (MVK)
(21 µL, 0.25 mmol) was added to the Schlenk tube. The reaction
mixture was stirred at 20 °C for 24–48 h. The solvent was removed
under reduced pressure and the residue was purified by flash col-
umn chromatography (SiO2, eluent: EtOAc/petroleum ether, 1:4)
to yield the corresponding aza-Morita–Baylis–Hillman adduct as a
colorless solid, which was immediately subjected to chiral HPLC
to analyse the enantiomeric excess.
Entry
Ar
Time
[h]
Yield[a]
[%]
ee[b]
[%]
Absolute
configuration[c]
1
2
3
4
5
6
7
8
9
10
C6H5 (1a)
24
24
24
18
12
18
36
12
18
36
2a, 49
2b, 53
2c, 72
2d, 85
2e, 54
2f, 62
2g, 26
2h, 60
2i, 84
2l, 62
83
80
94
83
90
88
91
94
81
76
S
S
S
S
S
S
S
S
S
S
Supporting Information (see also the footnote on the first page of
this article): Experimental details, 1H NMR spectroscopic and ana-
lytic data for dendritic chiral phosphane Lewis bases L1–L5 and
aza-Morita–Baylis–Hillman reaction products, and chiral HPLC
traces of the compounds shown in Tables 1–6 and Scheme 1.
p-MeC6H4 (1b)
p-ClC6H4 (1c)
p-BrC6H4 (1d)
m-NO2C6H4 (1e)
m-ClC6H4 (1f)
m-FC6H4 (1g)
p-NO2C6H4 (1h)
p-FC6H4 (1i)
Acknowledgments
p-EtC6H4 (1l)
We thank the Shanghai Municipal Committee of Science and Tech-
nology (04JC14083, 06XD14005), the Chinese Academy of Sci-
ences (KGCX2-210-01) and the National Natural Science Founda-
tion of China (20472096, 203900502, 20672127 and 20732008) for
financial support.
[a] Isolated yields. [b] Determined by HPLC with chiral column.
[c] Determined by the sign of specific rotation.
In conclusion, we have synthesized a series of novel chi-
ral sterically congested phosphane-amide bifunctional
Lewis bases L1–L3 and investigated their application in the
asymmetric aza-Morita–Baylis–Hillman reactions of N-sul-
fonated imines with MVK and EVK under mild conditions.
The corresponding aza-MBH adducts can be obtained in
good-to-excellent yields (up to 98%) and moderate-to-good
enantioselectivities (up to 91 or 93%) in DCM at room tem-
perature (20 °C). Efforts are underway to examine the effect
of these chiral bifunctional organocatalysts on other types
of asymmetric MBH or aza-MBH reactions and to improve
their chiral induction abilities in MBH or aza-MBH reac-
tions.
[1] For reviews of MBH and aza-MBH reactions, see: a) D. Basa-
vaiah, P. D. Rao, R. S. Hyma, Tetrahedron 1996, 52, 8001–
8062; b) S. E. Drewes, G. H. P. Roos, Tetrahedron 1988, 44,
4653–4670; c) E. Ciganek, Org. React. 1997, 51, 201–350; d) P.
Langer, Angew. Chem. Int. Ed. 2000, 39, 3049–3051; e) J.-X.
Cai, Z.-H. Zhou, C.-C. Tang, Huaxue Yanjiu 2001, 12, 54–64;
f) Y. Iwabuchi, S. Hatakeyama, J. Synth. Org. Chem. Jpn. 2002,
60, 2–14; g) D. Basavaiah, A. J. Rao, T. Satyanarayana, Chem.
Rev. 2003, 103, 811–892; h) G. Masson, C. Housseman, J. Zhu,
Angew. Chem. Int. Ed. 2007, 46, 4614–4628; i) D. Basavaiah,
K. V. Rao, R. J. Reddy, Chem. Soc. Rev. 2007, 36, 1581–1588;
j) Y.-L. Shi, M. Shi, Eur. J. Org. Chem. 2007, 2905–2916.
[2] For selected asymmetric aza-MBH reactions, see: a) M. Shi,
Y.-M. Xu, Angew. Chem. Int. Ed. 2002, 41, 4507–4510; b) M.
Shi, L. H. Chen, Chem. Commun. 2003, 1310–1311; c) D. Ba-
lan, H. Adolfsson, Tetrahedron Lett. 2003, 44, 2521–2524; d)
K. Matsui, S. Takizawa, H. Sasai, J. Am. Chem. Soc. 2005, 127,
3680–3681; e) M. Shi, L. H. Chen, C.-Q. Li, J. Am. Chem. Soc.
2005, 127, 3790–3800, and references cited therein; f) M. Shi,
Y.-M. Xu, Y.-L. Shi, Chem. Eur. J. 2005, 11, 1794–1802; g) I. T.
Raheem, E. N. Jacobsen, Adv. Synth. Catal. 2005, 347, 1701–
1705; h) K. Matsui, S. Takizawa, H. Sasai, Synlett 2006, 761–
765; i) A. Nakano, K. Takahashi, J. Ishihara, S. Hatakeyama,
Experimental Section
General Remarks: All solvents were purified by distillation. Unless
otherwise stated, all reactions were carried out under argon. 1H
NMR spectra were recorded with a Bruker AM-300 spectrometer
as solutions in CDCl3 with tetramethylsilane (TMS) as an internal
standard; J values are given in Hz. Mass spectra were recorded
with a HP-5989 instrument and HRMS were measured with a Fin-
2154
www.eurjoc.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2008, 2150–2155

Asymmetric Aza-Morita–Baylis–Hillman Reactions
Org. Lett. 2006, 8, 5357–5360; j) N. Utsumi, H. Zhang, F.
Tanaka, C. F. Barbas III, Angew. Chem. Int. Ed. 2007, 46,
1878–1880; k) Y.-L. Shi, M. Shi, Adv. Synth. Catal. 2007, 349,
2129–2135; l) Y.-H. Liu, M. Shi, Adv. Synth. Catal. 2008, 350,
122–128; m) M. Shi, L. H. Chen, W. D. Teng, Adv. Synth. Ca-
tal. 2005, 347, 1781–1789; n) Y. H. Liu, M. Shi, L. H. Chen,
Adv. Synth. Catal. 2006, 348, 973–979; o) K. Ito, K. Nishida,
T. Gotanda, Tetrahedron Lett. 2007, 48, 6147–6149; p) M. Shi,
C.-Q. Li, Tetrahedron: Asymmetry 2005, 16, 1385–1391; q) K.
Matsui, K. Tanaka, A. Horii, S. Takizawa, H. Sasai, Tetrahe-
dron: Asymmetry 2006, 17, 578–583; r) R. Gausepohl, P. Bus-
kens, J. Kleinen, A. Bruckmann, C. W. Lehmann, J. Klanker-
mayer, W. Leitner, Angew. Chem. Int. Ed. 2006, 45, 3689–3692;
s) M.-J. Qi, T. Ai, M. Shi, G. Li, Tetrahedron 2008, 64, 1181–
1186; for polymer-supported catalysts in MBH reactions, see:
t) J.-W. Huang, M. Shi, Adv. Synth. Catal. 2003, 345, 953–958;
u) L.-J. Zhao, H. S. He, M. Shi, P. H. Toy, J. Comb. Chem.
Res. 2004, 37, 601–610; e) J. Wang, H. Li, X. H. Yu, L. S. Zu,
W. Wang, Org. Lett. 2005, 7, 4293–4296; f) A. Berkessel, K.
Roland, J. M. Neudörfl, Org. Lett. 2006, 8, 4195–4198; g) M.-
J. Qi, M. Shi, Tetrahedron 2007, 63, 10415–10424; h) A. G. M.
Barrett, A. S. Cook, A. Kamimura, Chem. Commun. 1998,
2533–2534; i) Y. Iwabuchi, M. Nakatani, N. Yokoyama, S.
Hatakeyama, J. Am. Chem. Soc. 1999, 121, 10219–10220; j) K.-
S. Yang, W.-D. Lee, J.-F. Pan, K.-M. Chen, J. Org. Chem. 2003,
68, 915; k) N. T. McDougal, S. E. Schaus, J. Am. Chem. Soc.
2003, 125, 12094–12095; l) M. Shi, G.-N. Ma, J. Gao, J. Org.
Chem. 2007, 72, 9779–9781; for recent mechanistic investi-
gations of the MBH reaction, see: m) K. E. Price, S. J. Broad-
water, H. M. Jung, D. T. McQuade, Org. Lett. 2005, 7, 147–
150; n) V. K. Aggarwal, S. Y. Fulford, G. C. Lloyd-Jones, An-
gew. Chem. Int. Ed. 2005, 44, 1706–1708; o) K. E. Price, S. J.
Broadwater, B. J. Walker, D. T. McQuade, J. Org. Chem. 2005,
70, 3980–3987.
2004, 6, 680–683; v) L.-J. Zhao, C. K.-W. Kwong, M. Shi, P. H. [4] a) K. Sumi, T. Ikariya, R. Noyori, Can. J. Chem. 2000, 78,
Toy, Tetrahedron 2005, 61, 12026–12032; w) A. Corma, H.
GarcQa, A. Leyva, Chem. Commun. 2003, 2806–2807; x) H.-T.
Chen, S. Huh, J. W. Wiench, M. Pruski, V. S.-Y. Lin, J. Am.
Chem. Soc. 2005, 127, 13305–13311; y) C. K.-W. Kwong, R.
Huang, M. J. Zhang, M. Shi, P. H. Toy, Chem. Eur. J. 2007, 13,
2369–2376; z) X. Mi, S. Luo, H. Xu, L. Zhang, J.-P. Cheng,
Tetrahedron 2006, 62, 2537–2544.
697–703; b) P. N. M. Botman, O. David, A. Amore, J. Dinke-
laar, M. T. Vlaar, K. Goubitz, J. Fraanje, H. Schenk, H. Hiem-
stra, J. H. van Maarseveen, Angew. Chem. Int. Ed. 2004, 43,
3471–3473.
[5] Detailed procedures for the preparation of L1, L2 and L3 are
reported in the Supporting Information.
[6] The synthesis of L4 and L5 can be found in ref.[4a,2s] and their
spectroscopic data are reported in the Supporting Information.
Received: January 16, 2008
[3] For selected asymmetric MBH reactions, see: a) M. Shi, Y. H.
Liu, L. H. Chen, Chirality 2007, 19, 124–128; b) S. Kawahara,
A. Nakano, T. Esumi, Y. Iwabuchi, S. Hatakeyama, Org. Lett.
2003, 5, 3103–3105; c) J. E. Imbriglio, M. M. Vasbinder, S. J.
Miller, Org. Lett. 2003, 5, 3741–3743; d) S. J. Miller, Acc. Chem.
Published Online: March 10, 2008
(since its publication in Early View, a minor change
in one of the co-authors’ names has been made.)
Eur. J. Org. Chem. 2008, 2150–2155
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2155