Synthesis of chiral phosphorus reagents and their application in combination with lewis acid as a cocatalyst in morita-baylis-hillman reaction

Article abstract of DOI:10.1080/10426507.2011.568024

Two novel chiral thiophosphoramides and two chiral phosphoramidites were synthesized starting from (S)-α-phenylethylamine and (R)-(+) or (S)-(-)-1,1'-Bi-2-naphthol (BINOL), respectively, and their application in combination with Lewis acid as cocatalysts in asymmetric Morita-Baylis-Hillman (MBH) reaction was investigated. Dramatic rate acceleration (the corresponding adducts were obtained in fair to excellent chemical yield within 15 min-5 h) was observed in these chiral phosphorus reagents/Lewis acid cocatalyzed MBH reaction between 4-nitrobenzaldehyde and activated alkenes, and in one case, moderate enantioselectivity was achieved (the corresponding adduct's ee value is 44%). Copyright Taylor and Francis Group, LLC.

Full text of DOI:10.1080/10426507.2011.568024

This article was downloaded by: [McGill University Library]
On: 28 February 2013, At: 08:19
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Phosphorus, Sulfur, and Silicon and the
Related Elements
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/gpss20
Synthesis of Chiral Phosphorus Reagents
and Their Application in Combination
With Lewis Acid as a Cocatalyst in
Morita–Baylis–Hillman Reaction
Hongying Tang a , Xiamin Cheng b & Zhongbiao Zhang a
a Tianjin Key Laboratory of Water Environment and Resources,
Tianjin Normal University, Tianjin, P. R. China
b Institute of Elemento-Organic Chemistry, Nankai University,
Tianjin, P. R. China
Version of record first published: 06 Dec 2011.
To cite this article: Hongying Tang , Xiamin Cheng & Zhongbiao Zhang (2012): Synthesis of Chiral
Phosphorus Reagents and Their Application in Combination With Lewis Acid as a Cocatalyst in
Morita–Baylis–Hillman Reaction, Phosphorus, Sulfur, and Silicon and the Related Elements, 187:1, 8-15
To link to this article: http://dx.doi.org/10.1080/10426507.2011.568024
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation
that the contents will be complete or accurate or up to date. The accuracy of any
instructions, formulae, and drug doses should be independently verified with primary
sources. The publisher shall not be liable for any loss, actions, claims, proceedings,
demand, or costs or damages whatsoever or howsoever caused arising directly or
indirectly in connection with or arising out of the use of this material.

Phosphorus, Sulfur, and Silicon, 187:8–15, 2012
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2011.568024
SYNTHESIS OF CHIRAL PHOSPHORUS REAGENTS AND
THEIR APPLICATION IN COMBINATION WITH LEWIS
ACID AS A COCATALYST IN MORITA–BAYLIS–HILLMAN
REACTION
Hongying Tang,1 Xiamin Cheng,2 and Zhongbiao Zhang1
1Tianjin Key Laboratory of Water Environment and Resources, Tianjin Normal
University, Tianjin, P. R. China
2Institute of Elemento-Organic Chemistry, Nankai University, Tianjin, P. R. China
GRAPHICAL ABSTRACT
Cat.*
Me
Ph
H
S
Me
H
Ph
O
O
O
O
N
N
PNMe2
PN(i-Pr)2
S
N
P
NMe2
P
NMe2
O
Ph
H
Me
2
4
1
3
CHO
NO2
OH
*
OH
*
Cat.*/TiCl4
CH2Cl2
Et3N
r.t.
R
R
R
+
O2N
Cl
O2N
7
8
Reaction time: 15 min-5 h;
Yield (7+8): 46.1% 100%;
Ee: up to 44%.
Abstract Two novel chiral thiophosphoramides and two chiral phosphoramidites were
synthesized starting from (S)-α-phenylethylamine and (R)-(+) or (S)-(−)-1,1ꢀ-Bi-2-naphthol
(BINOL), respectively, and their application in combination with Lewis acid as cocatalysts in
asymmetric Morita–Baylis–Hillman (MBH) reaction was investigated. Dramatic rate accel-
eration (the corresponding adducts were obtained in fair to excellent chemical yield within
15 min–5 h) was observed in these chiral phosphorus reagents/Lewis acid cocatalyzed MBH
reaction between 4-nitrobenzaldehyde and activated alkenes, and in one case, moderate enan-
tioselectivity was achieved (the corresponding adduct’s ee value is 44%).
Keywords
Activated alkenes; chiral phosphoramidites; chiral thiophosphoramides;
Morita–Baylis–Hillman reaction; 4-nitrobenzaldehyde
Received 1 December 2010; accepted 28 February 2011.
This work is supported by the Research Fund for Young Scientist (No. 52LX29), the special research
program for Tianjin Binhai New Area (No. 52LE14) Tianjin Normal University, and Natural Science Foundation
of Tianjin (No. 08JCYBJC26900), Tianjin.
Address correspondence to Zhongbiao Zhang, Tianjin Key Laboratory of Water Environment and Resources,
Tianjin Normal University, Tianjin 300387, P. R. China. E-mail: ttxyx27@yahoo.com.cn
8

SYNTHESIS AND APPLICATION OF CHIRAL PHOSPHORUS REAGENTS
9
INTRODUCTION
The Morita–Baylis–Hillman reaction (MBH) is an effective carbon–carbon bond
forming reaction between an aldehyde or imine and an enone to generate densely multi-
functional adducts, secondary chiral alcohols, or amines under mild conditions.1 Because
of its enormous potential in organic synthesis, it has received much research interest.2,3 It
is known that the major problem of this reaction is its slow reaction rate (often days), and
numerous physical and chemical methods have been developed to accelerate the reaction
with some good results.4–6 Of these methods, chemical methods have the advantage of not
requiring specialized equipment, and so are more attractive. Kisanga and Verkade7 reported
a new type of three-coordinate phosphorus-catalyzed MBH reaction in combination with
TiCl4. It was found that in the catalytic system, the reaction was greatly accelerated and af-
forded the corresponding adducts in 5 min in good yields (88%–93%). Subsequently, they8
reported that several four-coordinate phosphorus thiophosphoramides catalyzed MBH re-
action, which also achieved good results, and the reaction was finished within 10 min in
88%–94% yields. Although many chiral organo catalysts have been developed to success-
fully catalyze several versions of the MBH reaction with high enantioselectivity, the rate
of conversion is still typically in the days range.9,10 Inspired by Verkade’s work, we envi-
sioned that in the situation of chiral phosphorus reagent/Lewis acid cocatalystic system, the
Lewis acid would activate the carbonyl group, and the chiral phosphorus compound would
function as a Lewis base to activate the alkenes. Then, the chiral cocatalystic system can
not only overcome the drawback of slow reaction rate of MBH reaction but also realize
asymmetric induction of MBH reaction and achieve good enatioselectivity. So, we report
here the synthesis of four chiral phosphorus reagents and their application as a catalyst in
asymmetric MBH reaction in combination with Lewis acid TiCl4 or BF3 Et2O.
RESULTS ANS DISCUSSION
Synthesis of Catalysts
The synthetic methods of compounds 1, 2 are very similar. We explored the syn-
thetic methods using compound 1 as the representative. First, we wished to achieve the
target directly through cyclization by using N,N-dimethylphosphorothioate dichloride and
diamine 511 in the presence of acid binding agents, but we failed. No target compound was
obtained either when using pyridine or dimethylaminopyridine as the base. There may be
two reasons for the reaction being difficult to carry out: larger steric hindrance of diamine
and inadequate activity of N,N-dimethyl phosphorothioate dichloride. We then attempted
another method. Under an inert atmosphere, diamine and hexamethylphosphorustriamide12
tended to produce the intermediate, three-coordinate phosphorous amide, and then com-
pound 1 was got through oxidation of the intermediate by sulfur. After 4-day refluxing,
we found that most intermediate were oxidized by O2 (31P NMR, δ 11.33 ppm). To avoid
the oxidation by O2, we adopted the method of condensation between activated hexam-
ethylphosphorustriamide by I2 and diamine 5, which greatly shortened the reaction time
and decreased the reaction temperature. Finally we succeeded in synthesizing the target
compound 1 with good yield (Scheme 1). Accordingly, in the same manner, we achieved
compound 2 (Scheme 1).
Following the literature procedure,11 compound 3 was easily synthesized through
condensation of BINOL and hexamethylphosphorustriamide with high yield (Scheme 2).
On the basis of compound 3, we first tried to get compound 4 by adding diisopropylamine

10
H. TANG ET AL.
Me
Me
Me
Ph
Ph
Ph
Ph
Ph
Ph
H
H
H
Br
CH3
NH2
S
NH
NH
N
N
N
I2/toluene/N2
60-70 oC
S8
Et3N
120 oC
+ Ph
+ P(NMe2)3
PNMe2
P
NMe2
N
Br
H
H
H
H
Me
Me
Me
5
1
Me
Ph
Me
Me
Ph
Ph
H
H
H
S
I2/toluene/N2
60-70 oC
S8
NMe2
N
O
S
NH
N
+
P(NMe2)3
S
P
P
S
NMe2
OH
O
2
Scheme 1
into the reaction mixture of 3 but failed. Subsequently, phosphorous chloride was syn-
thesized and reacted with diisopropylamine in the presence of acid binding agents, but no
product was obtained either. Lastly, we applied lithium diisopropylamide as the nucleophilic
reagent and synthesized compound 4 finally13 (Scheme 2).
OH
OH
O
O
P(NMe2)6/NH4Cl
CH3Cl
PNMe2
S-BINOL
3
OH
O
O
LDA
PCl3
refluxing
P Cl
O
PN(i-Pr)2
toluene
OH
O
6
R-BINOL
4
Scheme 2
Catalyst Evaluation
With these chiral phosphorus reagents in hand, we then carried out the asymmetric
MBH reaction between 4-nitrobenzaldehyde and activated alkenes, employing the phos-
phorus reagents as the catalysts in combination with Lewis acid.

SYNTHESIS AND APPLICATION OF CHIRAL PHOSPHORUS REAGENTS
11
Table 1 TiCl4/chiral phosphorus reagent catalyzed MBH reaction between 4-nitrobenzaldehyde and activated
alkene
Me
Ph
H
Me
Ph
H
O
O
O
O
S
N
N
PNMe2
PN(i-Pr)2
S
N
P
NMe2
P
NMe2
O
Ph
H
Me
2
4
1
3
CHO
OH
*
OH
Cat.*/TiCl4
CH2Cl2
Et3N
r.t.
R
R
R
*
+
O2N
Cl
O2N
NO2
7
8
Yield (%)
Entry
R
Catal.
Temp. (◦C)
Time (h)
7
8
[α]2D0a
1
2
3
4
5
6
7
8
9
10
13
14
15
16
COCH3(a)
COCH3(a)
COCH3(a)
CN(b)
1
1
1
1
1
2
2
2
2
2
3
4
3
4
r.t.
0
15 min
1
3
4
22.7
35.5
32.4
25.2
51.1b
25.3
40.7
46.1
28.2
65.5b
88.8b
100b
46.1b
55.0b
34.1
43.2
40.2
28.1
7, 0; 8, 0
7, 0; 8, 0
7, 0; 8, 0
7, 0; 8, 0
0
−78
0
CHO(c)
0
r.t.
0
5
COCH3(a)
COCH3(a)
COCH3(a)
CN(b)
15 min
32.9
45.1
46.2
30.1
7, 0; 8, 0
7, 0; 8, 0
7, 0; 8, 0
7, 0; 8, 0
0
1
3
4
5
4
5
4
4
−78
0
CHO(c)
0
0
0
0
COCH3(a)
COCH3(a)
CO2CH3(d)
CO2CH3(d)
−5.36 (44% ee)c
0
0
0
0
aMeasured by using a 1 g/100 mL concentration solution in chloroform.
bThe normal MBH adducts was obtained by the treatment of the reaction mixture with triethylamine.4b,14
cEnantiomeric excess and the absolute configuration R were deduced by compared the specific rotation with
literature.15
First, we investigated the catalytic activity of the phosphorus compounds with TiCl4 in
asymmetric MBH reaction in dichloromethane using 10 mol% chiral phosphorus reagents
and TiCl4. The results are summarized in Table 1.14,15
As shown in Table 1, the cocatalytic system of TiCl4 and chiral phosphorus reagent
dramatically accelerated the reaction. A mixture of chlorinated products and MBH adducts
were obtained with high yield in a relatively short time. The elimination of chlorinated
products to normal MBH adducts in the separation process resulted in the higher yield of
normal MBH adducts to chlorinated products. The two products were obtained by column
chromatography, but a single normal MBH adduct was obtained if using base such as
triethylamine (TEA) in the work-up process. The catalytic activity of thiophosphoramide
2 is higher than 1 in the MBH reaction. Under the same conditions, the yield of the

12
H. TANG ET AL.
.
Table 2 Chiral phosphorus reagent 4/BF3 OEt2 catalyzed MBH reaction between 4-nitrobenzaldehyde and MVK
CHO
O
OH
*
O
O
O
Cat. 4/BF3.OEt2
PN(i-Pr)2
+
CH2Cl2
O2N
NO2
8a
4
Entry
Cat. 4 (mol%)
Temp. (◦C)
Time (h)
Yield (%)
[α]2D0a
1
2
10
10
0
−78
4
4
24.4
25.2
−0.74 (6% ee)b
0
aMeasured by the using a 1 g/100 mL concentration solution in chloroform.
bEnantiomeric excess and the absolute configuration R were deduced by compared the specific rotation with
literature.15
products catalyzed by thiophosphoramide 2 is always higher than that catalyzed by 1
(Entries 1–5 versus 6–10). Unfortunately, in these cocatalytic systems, the two chiral
thiophosphoramides exhibited almost no chiral induction. However, it was gratifying that
an enantioselectivity of 44% ee was observed in case of the binary catalyst system of
chiral phosphoramidite 3 (Table 1, Entry 13). Generally, the MBH reaction took place well
with good yield in the binary catalyst system of the chiral three-coordinate phosphorus
reagents and TiCl4. Especially in the MBH reaction of methyl vinyl ketone (MVK) with
4-nitrobenzaldehyde catalyzed by compound 4, the corresponding addition product was
achieved quantitatively (Entry 14, yield, 100%).
.
Except for TiCl4, BF3 OEt2 could also be employed as the Lewis acid component
.
in the chiral phosphorus reagent 4/Lewis acid cocatalytic system. 4/BF3 OEt2 cocatalyzed
asymmetric MBH reaction of 4-nitrobenzaldehyde and MVK was preliminarily examined,
and the results are listed in Table 2.
As illustrated in Table 2, the catalytic activity of catalyst system 4/BF3.OEt2 was
much lower than that of 4/TiCl4. Similarly, almost racemic MBH adduct was attained in
this MBH reaction.
CONCLUSION
Two novel chiral thiophosphoramides and two chiral phosphoramidites have been
synthesized starting from readily available chiral resources (S)-α-phenylethylamine, and
(R)- or (S)-BINOL, respectively. These chiral phosphorus reagents have been successfully
.
applied in combination with Lewis acid, such as TiCl4 and BF3 Et2O, as cocatalysts for
MBH reaction between 4-nitrobenzaldehydes and different activated alkenes. Although
only a highest enantioselectivity of 44% ee was obtained, dramatic rate acceleration was
obtained. In most cases, the corresponding adducts were obtained in fair to excellent
chemical yield within 15 min–5 h.
EXPERIMENTAL
General: 1H NMR spectra were recorded in CDCl3 with a Bruker AMX-300 or Varian
400 MHz instrument using TMS as an internal standard. Specific rotations were measured

SYNTHESIS AND APPLICATION OF CHIRAL PHOSPHORUS REAGENTS
13
with a Perkin-Elmer 341MC polarimeter. Enantiomeric excesses were determined with
an HP-1100 instrument (chiral column; mobile phase: hexane/iPrOH). Elemental analyses
were conducted with a Yanaco CHN Corder MT-3 automatic analyzer. Melting points were
determined with a T-4 melting point apparatus and are uncorrected.
Synthesis of Catalysts Hexamethylphosphorustriamide
Hexamethylphosphorustriamde was prepared according to the literature procedure.11
Yield, 37.2%, bp 72 ◦C/20 mmHg, n1D6 1.4670.
N,Nꢁ-bis((S)-1-Phenylethyl)Ethane-1,2-Diamine 5
N,Nꢀ-bis((S)-1-Phenylethyl)Ethane-1,2-Diamine 5 was prepared according to the lit-
erature procedure.12 Yield, 45.9%, bp 162 ◦C–164 ◦C/2 mmHg, nD16 1.5505, [α]2D0 −63.41(c
1, CHCl3) (literature: [α]2D0 −69.2(c 1, CHCl3).
N-(1,3-Bis((S)-1-Phenylethyl)-2-Sulfanylene-1,3,2-
Diazaphospholidin-2-yl)-N-Methylmethanamine 1
Under argon atmosphere, the solution of hexamethylphosphoroustriamide (1.63 g,
10 mmol), iodine (0.13 g, 0.5 mmol) and anhydrous toluene (60 mL) was heated to 60 ◦C–
70 ◦C and stirred for 4 h. The reaction mixture gradually became cloudy from brown. After
the disappearance of the cloudy, N,Nꢀ-bis((S)-1-phenylethyl)ethane-1,2-diamine 5 (2.66 g,
10 mmol) was added to the clear solution and kept stirring at the same temperature for
5 h. To the clear yellow solution sulfur (0.26 g, 8 mmol) was added and gradually dis-
solved. After 0.5 h, the orange viscous liquid was obtained by removal of the solvent.
The pure product was got by chromatography purification (petroleum ether elution). Yel-
˜
low viscous liquid (2.46 g), Yield, 65.8%, [α]2D0-11.7 (c 1.66, CH2Cl2), 1H NMR (CDCl3,
400 MHz): δ 1.48 (d, J = 6.9Hz, 3H), 1.58 (d, J = 6.9, 3H), 2.62 (s, 3H), 2.66 (s, 3H),
2.68–3.11 (m, 4H), 4.30–4.28 (m, 1H), 4.47–4.57 (m, 1H), 7.21–7.44 (m, 10H); 31P NMR
(CDCl3, 400 MHz): δ 75.3; 13C NMR (CDCl3, 400 MHz): δ 20.6, 37.5, 42.6, 44.8, 127.0,
128.2, 128.8, 138.9. C20H25N3PS (373.17): calcd. C 64.32, H 7.56, N 11.25, S 8.58; found:
C 64.27, H 7.50, N 11.17, S 8.56.
N-((3aS,7aR)-Hexahydro-3-((S)-1-Phenylethyl)-2-Sulfanylenebenzo[d]
[1,3,2]Oxazaphosphol-2(3H)-yl)-N-Methylmethanamine 2
The method of synthesizing 2 was the same as that of 1. Yield, 40.7%, [α]2D0 +4.79 (c
0.94, C6H6). 1H NMR (CDCl3, 400 MHz): δ 1.15–1.29 (m, 2H), 1.52–1.79 (m, 9H), 2.91
(s, 3H), 2.95 (s, 3H), 3.10–3.18 (m, 1H), 3.79–3.87 (m, 1H), 4.519–4.63 (m, 1H), 7.21–7.48
(m, 5H); 31P NMR (CDCl3, 400 MHz): δ 85.7; 13C NMR (CDCl3, 400 MHz): δ 20.5, 21.6,
23.0, 26.2, 30.0, 35.6, 41.2, 54.1, 74.5, 127.3, 128.2, 128.9, 138.9. C16H25N2OPS (324.14):
calcd. C 59.24, H 7.77, N 8.63; found C 59.19, H 7.57, N 8.49.
O,Oꢁ-(S)-(1,1ꢁDinaphthyl-2,2ꢁ-Diyl)-N,N-Dimethylphosphoramidite 3
Under an argon atmosphere, (S)-BINOL (2.00 g, 7.00 mmol), hexamethylphospho-
rustriamide (1.40 g, 8.40 mmol), dry NH4Cl (0.20 g), and 50 mL of dry CHCl3 were heated

14
H. TANG ET AL.
to reflux till the material disappeared (monitored by TLC analysis, 50 min).11 After re-
moval of the solvent, the residue was purified by column chromatograph on silica gel (200–
300 meshes) to give white crystalline product (2.03 g), Yield, 80.9%, mp 190 ◦C–191 ◦C,
[α]2D0 579 (c 0.06, CHCl3).
O,Oꢁ-(R)-(1,1ꢁ-Dinaphthyl-2,2ꢁ-Diyl)-N,N-Di-i-Propylphosphoramidite 4
Under an argon atmosphere, (R)-BINOL (2.00 g, 7.00 mmol) and PCl3 (20 mL,
redistilled) were heated to reflux till the material disappeared (monitored by TLC analysis,
5 h).13 After removal of excess PCl3, dry benzene (3 × 25 mL) was added to take off the
remaining small amount of PCl3 to give pale yellow solid 6. Yield, 100%, 31P NMR (δ,
CDCl3): 178.4.
Under an argon atmosphere, to a solution of compound 6 (0.96 g, 2.7 mmol) in dry
toluene (25 mL), n-BuLi was added dropwise (1.66 mL of 1.98 M solution in hexane)
◦
at −60 C. Then it was warmed up to room temperature naturally and stirred for 5 h.
The reaction mixture was filtered and purified by chromatography on silica gel (200–300
meshes, petroleum ether/CH2Cl2 = 2/1) to give the pure amidite as a colorless amorphous
compound (0.40 g). Yield, 35.1%, mp 197 ◦C–199 ◦C, [α]D20 −571.33 (c 0.60, CHCl3),31P
NMR (CDCl3, 400 MHz): 153.0.
General Procedure for Chiral Phosphorus Reagents and TiCl4 Catalyzed
Asymmetric MBH Reaction of 4-Nitrobenzaldehydes and Activated Alkenes
The solution of chiral phosphorus reagents and TiCl4 (0.2 mmol, 10 mmol%, re-
spectively), activated alkene (6 mmol), and 4-nitrobenzaldehyde (2 mmol) in anhydrous
CH2Cl2 (25 mL) was stirred at ambient temperature until the raw material disappeared
(monitored by TLC). Then the reaction was quenched by adding saturated aqueous sodium
bicarbonate solution and separated. TEA (0.4 g) was added to the organic phase and stirred
overnight until the complete transformation of all the chlorinated products A into MBH
product B (monitored by TLC). The mixture was washed in turn with dilute hydrochloric
acid, saturated sodium bicarbonate solution, and saturated salt water, and then dried by
anhydrous sodium sulfate overnight. After removal of the solvent, the residue was purified
by column chromatography on silica gel (200–300 mesh, gradient elution with petroleum
ether/ethyl acetate = 6/1) to afford the product.
.
General Procedure for 4/BF3 Et2O Catalyzed Asymmetric MBH Reaction
.
The solution of BF3 Et2O (0.1 mmol) in ether was added to the solution of 4
(0.1 mmol, 10 mmol%), MVK (0.25 mL, 3 mmol), and 4-nitrobenzaldehyde (0.15 g, 3
mmol) in anhydrous CH2Cl2 (25 mL), then stirred at the reaction temperature until the
raw material disappeared (monitored by TLC). After completion of the reaction, TEA was
added and warmed up to room temperature. The mixture was washed in turn with dilute
hydrochloric acid, saturated sodium bicarbonate solution, and saturated salt water, and then
dried by anhydrous sodium sulfate overnight. After removal of the solvent, the residue was
purified by column chromatography on silica gel (200–300 mesh, gradient elution with
petroleum ether/ethyl acetate = 6/1) to afford the product.

SYNTHESIS AND APPLICATION OF CHIRAL PHOSPHORUS REAGENTS
15
REFERENCES
1. (a) Morita, K.; Suzuki, Z.; Hirose, H. Bull. Chem. Soc. Jpn. 1968, 41, 2815; (b) Baylis, A. B.;
Hillman, M. E. D. Ger. Offen., 2155113; Chem. Abstr. 1972, 77, 34174g.
2. (a) Basavaiah, D.; Rao, P. D.; Hyma, R. S. Tetrahedron 1996, 52, 8001-8062; (b) Ciganek, E. Org.
React. 1997, 51, 201-350; (c) Langer, P. Angew. Chem. Int. Ed. 2000, 39, 3049-3052; (d) Cai,
J. X.; Zhou, Z. H.; Tang, C. C. Hauxue Yanjiu 2001, 12, 54-64; (e) Basavaiah, D.; Rao, A. J.;
Satyanarayana, T. Chem. Rev. 2003, 103, 811-892; (f) Drewes, S. E.; Roos, G. H. P. Tetrahedron
1988, 44, 4653-4670; (g) Wei, Y.; Shi, M. Accounts Chem. Res. 2010, 43(7), 1005-1018; (h) Yu,
Y.; Huang, L. J.; Teng, D. W. Huaxue Yu Shengwu Gongcheng 2009, 26(11), 7-11; (i) Basavaiah,
D.; Rao, K. V.; Reddy, R. J. Chem. Soc. Rev. 2007, 36, 1581-1588; (j) Singh, V.; Batra, S.
Tetrahedron 2008, 64, 4511-4574.
3. (a) Takizawa, S., Yakugaku Zasshi 2009, 129(10), 1201-1210; (b) Gowrisankar, S.; Lee, H. S.;
Kim, S. H.; Lee, K. Y.; Kim, J. N. Tetrahedron 2009, 65(43), 8769-8780; (c) Declerck, V.;
Martinez, J.; Lamaty, F. Chem. Rev. 2009, 109(1), 1-48; (d) Ma, G. N.; Jiang, J. J.; Shi, M.; Wei,
Y. Chem. Comm. 2009, 5496-5514; (e) Yang, C. H.; Fan, J. F.; Qiao, L. G. Youji Huaxue 2008,
28(2), 175-180; (f) Iwabuchi, Y.; Hatakeyama, S. Yuki Gosei Kagaku Kyokaishi 2002, 60(1),
2-14; (g) Krishna, P. R.; Sharma, G. V. M. Mini-Rev. Org. Chem. 2006, 3(2), 137-153.
4. (a) Souza, R. O. M. A.; Miranda, L. S. M. Mini-Rev. Org. Chem. 2010, 7(3), 212-220; (b) Cai, J.
X.; Zhou, Z. H.; Zhao, G. F.; Tang, C. C. Org. Lett. 2002, 4(26), 4723-4725; (c) Anstiss, C.; Liu,
F. Tetrahedron 2010, 66(29), 5486-5491; (d) Lee, K. Y.; GowriSankar, S.; Kim, J. N. Tetrahedron
Lett. 2004, 45, 5485-5488.
5. (a) Byun, H. S.; Reddy, K. C.; Bittman, R. Tetrahedron Lett. 1994, 35, 1371-1374; (b) Rezgui,
F.; Gaied, M. M. E. Tetrahedron Lett. 1998, 5965-5966; (c) Auge, J.; Lubin, N.; Lubineau, A.
Tetrahedron Lett. 1994, 35, 7947-7948; (d) Basavaiah, D.; Krishnamacharyulu, M.; Rao, A.
J. Synth. Comm. 2000, 30, 2061-2069; (e) Yu, C. Z.; Liu, B.; Hu, L. Q. J. Org. Chem. 2001, 66,
5413-5418.
6. (a) Kim, E. J.; Ko, S. Y. Helvetica Chimica Acta 2003, 86, 894-899; (b) Rose, P. M.; Clifford,
A. A.; Rayner, C. M. Chem. Comm. 2002, 968-971; (c) Grainger, R. S.; Leadbeater, N. E.;
Pa`amies, M. E. Catal. Comm. 2002, 3, 449-452; (d) Kumar, A.; Pawar, S. S. J. Mol. Catal. A:
Chem. 2004, 211, 43-47; (e) Kataoka, T.; Kinoshita, H. Eur. J. Org. Chem. 2005, 45-58.
7. Kisanga, P. B.; Verkade, J. G. J. Org. Chem. 2002, 67, 426-430.
8. Verkade, J. G.; Angew. Chem. Int. Ed. 2003, 42, 5054-5056.
9. (a) Shi, Y.-L.; Shi, M. Eur. J. Org. Chem. 2007, 2905-2916; (b) Masson, G.; Housseman, C.;
Zhu, J. Angew. Chem., Int. Ed. 2007, 46, 4614-4618; (c) Menozzi, C.; Dalko, P. I. Enantiosel.
Organocatal. 2007, 151-187; (d) Shi, Y.-L.; Shi, M. Eur. J. Org. Chem. 2007, 2905-2916.
10. (a) Tang, H. Y.; Gao, P.; Zhao, G. F.; Zhou, Z. H.; Zhou, Q. L.; Tang, C. C. Tetrahedron Lett.
2006, 47, 5717-5721; (b) Masson, G.; Housseman, C.; Zhu, J. Angew. Chem. Int. Ed. 2007, 46,
4614-4628; (c) Tang, H. Y.; Zhao, G. F.; Zhou, Z. H.; Gao, P.; He, L. N.; Tang, C. C. Eur. J. Org.
Chem. 2008, 126-135; (d) Tang, H. Y.; Gao, P. Zhao, G. F.; Zhou, Z. H.; He, L. N.; Tang, C. C.
Catal. Comm. 2007, (8), 1811-1814; (e) Saa´, J. M.; Mansilla, J. Molecules 2010, 15, 709-734.
11. Hulst, R. Koende, V. N.; Feringa, B. L. Tetrahedron: A 1994, 5, 699-708.
12. Ho, S. Y.; Sharpless, K. B. J. Org. Chem. 1986, 51, 5413-5415.
13. Arnold, L. A.; Imbos, R.; Mandoli, A.; Vries, A. H. M.; Feringa, B. L. Tetrahedron 2000, 56,
2865-2878.
14. (a) Shi, M.; Jiang, J. K. Tetrahedron 2000, 56, 4793-4796; (b) Iwama, T.; Kinoshita, H.; Kataoka,
T. Tetrahedron Lett. 1999, 40, 3741-3744; (c) Shi, M.; Jiang, J. K.; Feng, Y. S. Org. Lett. 2000,
2(16), 2397-2400.
15. T. Oishi, H. Oguri, M. Hirama, Tsetrahedron: A 1995, 6(6), 1241-1244.