New silver(I)-monophosphine complex derived from chiral Ar-BINMOL: Synthesis and catalytic activity in asymmetric vinylogous Mannich reaction

Article abstract of DOI:10.1016/j.tet.2013.07.105

A new family of C₂-axially chiral monophosphines (Ar-NNPs) from Ar-BINMOLs was developed for silver-catalyzed asymmetric vinylogous Mannich reaction of (furan-2-yloxy)trimethylsilane with aromatic aldimines. It was found that the enantioselective vinylogous Mannich-type reactions of trimethylsiloxyfuran with aldimines are catalyzed efficiently by silver(I) complexes of the Ar-BINMOL-derived chiral monophosphine. This procedure displays wide aldimine versatility, excellent yields (up to 99% isolated yields), moderate to good enantioselectivity (up to 78%ee) and exceptional diastereoselectivity (>99:1 dr) in most cases examined. The molecular structure of silver-monophosphine complex was confirmed by X-ray analysis and revealed that the benzyl group on chiral monophosphine provided dual function with weak silver-π/π-π stacking and steric repulsion to favour the diastereoselective Re-nucleophilic addition of siloxyfuran to imine.

Full text of DOI:10.1016/j.tet.2013.07.105

Tetrahedron 69 (2013) 8777e8784
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
New silver(I)emonophosphine complex derived from chiral Ar-
BINMOL: synthesis and catalytic activity in asymmetric vinylogous
Mannich reaction
Long-Sheng Zheng a, Li Li a, Ke-Fang Yang a, Zhan-Jiang Zheng a, Xu-Qiong Xiao a,
,b,
Li-Wen Xu a
*
a Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Hangzhou Normal University, Hangzhou 310012, PR
China
b State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000,
PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 31 May 2013
Received in revised form 13 July 2013
Accepted 22 July 2013
Available online 11 August 2013
A new family of C2-axially chiral monophosphines (Ar-NNPs) from Ar-BINMOLs was developed for silver-
catalyzed asymmetric vinylogous Mannich reaction of (furan-2-yloxy)trimethylsilane with aromatic al-
dimines. It was found that the enantioselective vinylogous Mannich-type reactions of trimethylsilox-
yfuran with aldimines are catalyzed efficiently by silver(I) complexes of the Ar-BINMOL-derived chiral
monophosphine. This procedure displays wide aldimine versatility, excellent yields (up to 99% isolated
yields), moderate to good enantioselectivity (up to 78%ee) and exceptional diastereoselectivity (>99:1
dr) in most cases examined. The molecular structure of silveremonophosphine complex was confirmed
by X-ray analysis and revealed that the benzyl group on chiral monophosphine provided dual function
Keywords:
Silver
Ar-BINMOL
Phosphine
Vinylogous Mannich reaction
Asymmetric catalysis
with weak silvere
p/pep stacking and steric repulsion to favour the diastereoselective Re-nucleophilic
addition of siloxyfuran to imine.
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
Functional and optically pure five-membered g-butenolides are
valuable intermediates in organic synthesis and also are the struc-
During the past decade, intense research efforts have been de-
voted to develop effective catalyst systems using new ligands and
related silver complex.1 Especially, the chiral silver complexes have
been recognized as attractive and privileged catalysts in many or-
ganic reactions to prepare important optically active molecules.2
Whilst many elegant methods have been established for the
preparation of the silverephosphine complex, its successful
implementation in asymmetric catalysis is rather limited in com-
parison to that of other transition metals, such as palladium, rho-
dium, etc. New silverephosphine complex with specific catalytic
behaviours and good enantioselective induction could be con-
structed and controlled by chiral phosphine. However, synthesizing
such chiral phosphine with good catalytic activity is still a great
challenge. In this context, we became interested in the synthesis of
chiral phosphine ligands and its potential application as a key el-
tural motifs frequently found in many natural products.3 Among the
known synthetic methods to highly functionalized
g-butenolides
bearing amino groups, the Lewis acid-catalyzed vinylogous
Mannich-type reaction of trimethylsiloxyfuran is considered to be
one of the most efficient synthetic approaches.4 However, the syn-
thesis of optically pure
g-butenolides through asymmetric vinyl-
ogous Mannich-type reaction has limited exploration.3e5 The first
asymmetric vinylogous Mannich-type reaction of trimethylsilox-
yfuran catalyzed by titanium complex was reported by Martin and
Lopez in 1999, in which both the enantioselectivities and yields were
only moderate (up to 54%ee).6 The development of effective chiral
catalyst system for the enantioselective synthesis of g-butenolide
derivatives has been realized as an important topic since then.7e10
Among these catalyst systems, silverephosphine complexes con-
taining Schiff base or oxazoline moiety were proved to be powerful
chiral catalysts in the asymmetric vinylogous Mannich-type reaction
of trimethylsiloxyfuran. For example, in 2006, Hoveyda and co-
workers reported a highly efficient and practical method for catalytic
asymmetric vinylogous Mannich reactions of trimethylsiloxyfuran
and 2-aminophenol-derived imines.8 With the similar type of amino
acid-derived chiral phosphine containing Schiff base motif, Hoveyda
ement in the preparation of functional
g-butenolides through
silver-catalyzed vinylogous Mannich-type reaction.
* Corresponding author. Tel.: þ86 571 28867756; fax: þ86 571 28865135; e-mail
addresses: licpxulw@yahoo.com, liwenxu@hznu.edu.cn (L.-W. Xu).
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.07.105

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L.-S. Zheng et al. / Tetrahedron 69 (2013) 8777e8784
and co-workers have also found that various imines could be suit-
able substrates in the silver-catalyzed vinylogous Mannich re-
actions.9 Recently, Shi and co-workers reported an asymmetric
high yield
R
OH perfect CT
OH
R
OH
TMSCl/NaI
[1,2]-Wittig
OH
OH
synthesis of
g-butenolide derivatives through silver-catalyzed
>99% yield
rearrangement
vinylogous Mannich reactions of versatile imines in the presence
BINOL
1a-c
of axial chiral phopshineeoxazoline ligands.10
Ar-BINMOL
>99%ee
2a-c
The work of Hoveyda,8,9 Shi10 and Zanardi7h was significant be-
cause it showed that the chiral phosphine ligands having an addi-
tional nitrogen group are essential to give the vinylogous Mannich
adducts in good enantioselectivity. This led us to explore the effec-
tiveness of BINOL (1,10-binaphthalene-2,20-diol)-derived or BINAP
(2,20-bis(diphenylphophino)-1,10-binaphthyl)-like monophosphines
in asymmetric vinylogous Mannich reaction. To the best of our
knowledge, the enantioselective activity of simple monophosphines
lack of additional heteroatom on this ligand has not been explored.
In addition, although enormous research efforts have been in-
terested in the synthesis of chiral ligands,11 the development of new
chiral phosphine ligands with good enantioselectivity remains a vital
challenge in catalytic asymmetric reactions. Herein, we report the
facile synthesis of novel axially chiral monophosphine ligands for
asymmetric vinylogous Mannich reactions. This work reveals that
the silver-catalyzed asymmetric vinylogous Mannich reaction of
trimethylsiloxyfuran with aldimines can proceed smoothly to give
Pd(OAc)2 ( 6mol%)
Ph2P(=O)H,
dppb
R
R
Tf2O/Et3N
96% yield
Ph
Ph
O
OTf
P
DIPEA, DMSO
100 oC, 60 h
52-65% yield
3a-c
4a: R = H
4b: R = 2-OMe
4c: R = 4-Me
R
HSiCl3
Et3N
Ph
Ph
P
toluene
100 oC, 18 h
>95% yield
5a: R = H
5b: R = 2-OMe
5c: R = 4-Me
the corresponding
g-butenolide derivatives in moderate to good
enantioselectivity in the presence of the simple chiral mono-
phosphine under mild conditions.
OH
as above procedures
OH
PPh2
2. Results and discussion
5d
1d
We initiated our studies by synthesizing a novel axially mono-
Scheme 1. The synthesis of novel Ar-BINMOL-derived monophosphines (Ar-NNPs).
phosphine from our Ar-BINMOL (1,10-binaphthalene-2-
a-arylme-
thanol-20-ol) ligand that is prepared from C2 axial 1,10-
binaphthalene-2,20-diol (BINOL) through [1,2]-Wittig rearrange-
ment reaction.12 We have identified that the [1,2]-Wittig rear-
rangement was a practical procedure for the construction of novel
diol ligands with both axial and sp3 central chirality that could act
as efficient chiral ligands in various transformations.13 Because of
the established importance and interesting effect of the rotatable
benzyl group on this type of chiral compounds in asymmetric ca-
talysis,14 it has become necessary to consider the preparation of Ar-
BINMOL-derived chiral monophosphine.
As shown in Scheme 1, the axially chiral monophosphine ligands
5 were prepared in four steps easily from the available starting Ar-
BINMOLs.12,13e,14 The deoxygenation of secondary alcohol was car-
ried out successfully in the presence of large amount of TMSCl
(6 equiv) and NaI (6 equiv), which led to the intermediate 2 in
excellent yields. Treatment of 2 with trifluoromethanesulfonic an-
hydride (Tf2O) and triethylamine afforded, in almost quantitative
yield, the corresponding products 3aec that was then submitted to
palladium-catalyzed cross coupling of 3 and diphenylphosphite
under the reported conditions.15
Fig. 1. Crystal structure of chiral monophosphine ligand 5a (Ph-NNP), hydrogen atoms
The desired chiral phosphites 4aed then underwent reduction
on treatment with HSiCl3 (5 equiv) and triethylamine (6 equiv) in
toluene at 100 ꢀC for 18 h to furnish Ar-BINMOL-derived chiral
monophosphines 5aed (Ar-NNPs) in excellent yields (>95%). No-
tably, these monophosphines 5aed exhibit good air stability. The
stereochemical identify of Ar-NNPs 5 was verified by an X-ray
crystal structure determination of monophosphine 5a. As shown in
Fig. 1, although there is no any functional heteroatom-based group
excluding the phosphine centre, this chiral phosphine is suggested
to be BINAP-like monophosphine. This structure or conformation of
Ph-NNP 5a {Ph-NNP: (R)-(1-(2-benzylnaphthalen-1-yl)naph-
thalen-2-yl)diphenylphosphine} is interesting since the aromatic
ring of rotatable benzyl group can provide possible aromatic in-
teractions between catalyst system and substrate to enhance the
enantioselective induction.
have been omitted for clarity (CCDC 918256).
Subsequently, we began to evaluate the activity of enantiose-
lective induction of the novel chiral ligands 5 in silver-catalyzed
vinylogous Mannich-type reaction of trimethylsiloxyfuran with
aldimines. As the data summarized in Table 1 illustrated, among
these simple chiral monophosphines 5aed of Scheme 1, ligand 5a
(Ph-NNP) exhibited the best catalytic performance in term of
enantioselectivity (76%ee) and isolated yield (entries 1e4). Com-
parably, the use of classic and famous bisphosphine, (R)-BINAP [(R)-
(þ)-2,20-bis(diphenylphosphino)-1,10-binaphthyl], resulted in the
formation of 7a in only 64%ee and 90% yield (entry 5), which
showed the novel chiral monophosphine 5a gave better enantio-
selective induction in this reaction than that of (R)-BINAP (ee: 76%

L.-S. Zheng et al. / Tetrahedron 69 (2013) 8777e8784
8779
vs 64%, and yield: 99% vs 90%, respectively). Similarly to previous
studies,7,8,16 it was revealed that i-PrOH played important role in
the asymmetric transformations of siloxyfurans (entries 1 and 6).
Then the positive effect of i-PrOH promoted us to investigate other
alcohols as additives in this reaction. Furthermore, the effect of
second metal catalyst and other silver salts on the enantiose-
lectivity of chiral monophosphine ligand 5a was also studied. Table
1 illustrates representative results of the additives and various
metal catalysts (entries 6e19). Unfortunately, the improvement of
enantioselectivity in this reaction was unsuccessful under these
conditions. Initially, the use of AgClO4, Ag2O and AgOTf instead of
AgOAc led to the formation of desired product 7a in low to mod-
erate yields (46e89% yield) and poorer enantioselectivities and
diastereoselectivities (entries 7e9, for AgOTf, 58:42 dr, no
enantioselectivity).
trimethylsilyl N-trimethylsilylacetimidate (BSA) disturbed the
enantioselective induction of chiral phosphine ligand 5a in this re-
action, in which almost no enantioselectivity and low yield of 7a was
detected (entry 16). It should be also noted that the introduction of
Cu(OAc)2 as a co-catalyst, resulted in excellent enantioselectivity
(75%ee) for the adduct 7a, while the enantioselectivity and diaster-
eoselectivity is low when Cu(OTf)2 was used in this reaction (entries
17 and 18). Luckily, the addition of water in this silverephosphine
catalyst system also led to good yield and enantioselectivity (entry
19). However, the use of classic desilylation reagent, TBAF (tetrabu-
tylammonium fluoride), led to almost no reaction (entry 20). These
results showed that the effect of a hydrogen donor as an additive in
the catalytic asymmetric Mannich reaction is pronounced in both
the conversion and enantioselectivity.16
In light of above findings, we next examined the generality of
this vinylogous Mannich-type reaction with various simple aldi-
mines and trimethylsiloxyfuran under the optimized conditions. As
shown in Scheme 2, various aldimines can be used in this reaction
in the presence of the Ar-BINMOL-derived monophosphine ligand
5a. Whereas the vinylogous Mannich-type reaction of aldimines
with 2-methoxyphenyl group results in moderate yield of 7j, most
of reactions proceed to >90% isolated yields and afford a single
diastereomer (>99:1) as well as moderate to good enantiose-
lectivities (7ael). Then, to enlarge the scope of this silvere5a
complex-catalyzed vinylogous Mannich-type reaction, we in-
vestigated the reactivity of alkyl aldehyde and 2-
methoxybenzenamine -derived aldimine 6m (N-(cyclohexyl-
methylene)-2-methoxybenzenamine) and cinnamaldehyde-de-
rived aldimine 6o N-(3-phenylallylidene)benzenamine in this
reaction. Unfortunately, these types of substrate are not suitable for
Table 1
Effect of chiral ligands and additive for the asymmetric vinylogous Mannich-type
reaction of trimethylsiloxyfuran with aldimine 6aa
N
AgX (5 mol%)
HN
ligand 6 (5 mol%)
HN
+
6a
additive (1.5 equiv)
+
DCM, -78 oC - RT
O
O
O
O
OTMS
O
anti-7a
syn-8a
Entry
AgX
Ligand
Additive
Yieldb (%)
drc 7a/8a
eed/%
1
2
3
4
AgOAc
AgOAc
AgOAc
AgOAc
AgOAc
AgOAc
AgClO4
Ag2O
AgOTf
AgOAc
AgOAc
AgOAc
AgOAc
AgOAc
AgOAc
AgOAc
AgOAc
AgOAc
AgOAc
AgOAc
5a
5b
5c
i-PrOH
i-PrOH
i-PrOH
i-PrOH
i-PrOH
d
99
97
92
95
90
77
89
46
88
91
89
92
93
95
46
28
97
95
94
Trace
>99:1
>99:1
>99:1
>99:1
99:1
>99:1
66:34
99:1
58:42
>99:1
99:1
98:2
99:1
>99:1
61:39
65:35
99:1
77:23
99:1
d
76
65
66
74
64
44
0
the
present
silveremonophosphine-catalyzed
vinylogous
5d
BINAP
5a
5a
5a
5a
5a
5a
5a
5a
5a
5a
5a
5a
5a
5a
5a
Mannich-type reaction of trimethylsiloxyfuran with 6m and 6o
(17e30%ee). Even other Ar-NNPs (monophosphines 5bed) gave
better enantioselectivities (Scheme 3, 7m and 7o) in comparison to
that of Ph-NNP 5a, we observed that the use of these mono-
phosphines as the chiral ligands in silver-catalyzed vinylogous
Mannich reaction of alkyl imine was not satisfied because of
moderate yields (38e56%) and low to moderate enantioselectivities
(5e45%ee). As an explain for the pronounced difference in these
substrates, the possible non-covalent interactions, including hy-
5
6e
7e
8
d
i-PrOH
i-PrOH
HMDS
EtOH
MeOH
BnOH
PhNH2
i-Pr2NH
BSAg
55
0
9
10
11
12
13
14
15f
16
17
18
19
20
74
74
68
73
71
65
0
75
0
74
d
drogen bonding and aromatic
pep stacking, between catalyst and
Cu(OAc)2
Cu(OTf)2
H2O
substrate would play important role in the enantioselective vinyl-
ogous Mannich reaction. Fortunately, the conversion of heterocyclic
aldimine, such as 6n (N-(pyridin-3-ylmethylene)benzenamine),
was excellent to give the corresponding product 7n in 88% isolated
yield and 78%ee as well as excellent diastereoselectivity (>99:1 dr).
Although the enantioselective induction of chiral monophosphines
(Ar-NNPs) is not perfect, these reaction results described here in-
dicate that the simple and axially chiral monophosphine without
other heteroatom-based groups for additional binding site is also
a promising type of chiral ligand to give enantioselective induction
in this reaction.
To illustrate the mechanistic rationale for the Ag-catalyzed
vinylogous Mannich-type reaction, electrospray ionization mass
spectrometry (ESI-MS) was carried out for determination of pos-
sible silver(I)ephosphine complex (Fig. S1e4, see Supplementary
data). ESI(þ)-MS was able to intercept the key silver complex, Ag
with one or two phosphine ligand 5a of m/z 635.15 [AgþPh-NNP]þ
and m/z 1164.78 or 1164.82 [2AgþPh-NNPþH]þ, respectively (Fig. 2,
and also see Supplementary data).
TBAFh
a
Reaction conditions: 6a (0.25 mmol), trimethylsiloxyfuran (1.5 equiv), additive
(1.5 equiv), AgX (5 mol %), ligand (5 mol %), DCM (1.8 mL), and the reaction was
carried out at ꢁ78 ꢀC to rt for 18 h.
b
Isolated yield after chromatography.
c
Determined by 1H NMR and confirmed by chiral HPLC and GC/MS.
d
The enantiomeric excess of 7a was determined by chiral HPLC analysis.
No addition of any additives.
Both the enantiomeric excess of 7a and 8a are 65%ee.
BSA is trimethylsilyl N-trimethylsilylacetimidate.
e
f
g
h
TBAF is tetrabutylammonium fluoride.
Except i-PrOH, the use of various primary alcohols as additive,
such as MeOH, EtOH, BnOH, also led to excellent isolated yield and
promising enantioselectivity (entries 11e13, 68e75%ee). In-
terestingly, HMDS (hexamethyldisilazane) was also a good additive
that gave the desired product 7a in 91% yield and 74%ee. Thus the
role of different amines or organosilicon compound (BSA) was then
investigated in this reaction. Similarly, aniline gave the same level of
enantioselectivity and diastereoselectivity as well as isolated yield
(entry 14, 75%ee). However, the secondary amine, diisopropylamine,
inhibited this reaction as both the yield and diastereoselectivity
were low (entry 15, 46% yield, 61:39 dr). Different from HMDS,
In addition, the molecular structure of silvere5a (Ph-NNP)
complex is confirmed by X-ray analysis and depicted in Fig. 3. The
structure of silvere5a (Ph-NNP) complex represents a unique
binding mode for planar silver-linked acetate and reflects acetate
anion is important in the silver complex, in which the silver atom is
essentially four-coordinated by the phosphine atom, two oxygen

8780
L.-S. Zheng et al. / Tetrahedron 69 (2013) 8777e8784
+
AcO
R2
R2
N
AgOAc (5 mol%)
R1
Ph
+
ligand 5a (5 mol%)
P
HN
6
Ag
+
i-PrOH (1.5 equiv)
DCM, -78 oC, 10 h,
RT, 4 h
O
O
Ph
P
OTMS
C
H AgP
PPh
AgP
R1
Exact Mass: 635.1058
Mol. Wt.: 636.4895
Ag
H
O
7
AcO
Cl
OEt
Cl
C
Exact Mass: 1163.3065
Mol. Wt.: 1165.1108
HN
HN
HN
HN
O
O
O
O
O
O
O
O
Cl
7a
7b
7c
7d
99% yield
>99:1 dr
76%ee
96% yield
>99:1 dr
76%ee
92% yield
>99:1 dr
53%ee
97% yield
>99:1 dr
73%ee
Fig. 2. ESI(þ)-MS for the vinylogous Mannich reaction mixtures of AgOAc, imine 6a, i-
PrOH, 2-(trimethylsilyloxy)furans and monophosphine ligand 5a (Ph-NNP) in DCM.
Cl
Cl
Br
HN
HN
HN
O
HN
O
O
O
O
O
O
O
Br
Br
7e
7h
7f
7g
98% yield
>99:1 dr
78%ee
91% yield
>99:1 dr
76%ee
94% yield
>99:1 dr
74%ee
96% yield
>99:1 dr
77%ee
Br
Br
O
Cl
MeO
HN
H
N
HN
HN
O
O
O
O
Br
O
O
O
7i
7j
7k
7l
94% yield
>99:1 dr
63%ee
75% yield
>99:1 dr
63%ee
96% yield
>99:1 dr
56%ee
96% yield
97:3 dr
66%ee
MeO
MeO
HN
HN
HN
N
O
Fig. 3. Crystal structure of chiral silvere5a monophosphine complex, hydrogen atoms
have been omitted for clarity (CCDC 925867).
O
O
O
O
O
7n
7o
7m
88% yield
>99:1 dr
78%ee
57% yield
>99:1 dr
17%ee
50% yield
94:6 dr
atoms and one central carbon atom of acetate anion. Important
bond lengths and angles of the silver complex are listed in Table 2
and reveal the distance of silver atom and two oxygen of acetate is
significantly different. The interaction between acetate silver-
ephosphine-linked aromatic ring and the benzyl group-linked
naphthyl ring looks repulsive, and a promising and positive splay
angle clearly supports this observation. The large cavity between
parallel aromatic rings may be beneficial to the interaction of silver
with aldimine or trimethylsiloxyfuran, which guarantees the se-
lective addition of trimethylsiloxyfuran to aldimine.
30%ee
Scheme 2. Ag-catalyzed asymmetric vinylogous Mannich-type reaction of trime-
thylsiloxyfuran and aldimines.
R2
R2
N
AgOAc (5 mol%)
R1
HN
O
ligand 5b-d (5 mol%)
6
+
i-PrOH (1.5 equiv)
DCM, -78 oC, 10 h,
RT, 4 h
O
Table 2
O
OTMS
ꢀ
ꢀ
Selected bond lengths (A) and angles ( ) for silvere5a (Ph-NNP)
R1
O
O
7
ꢀ
Bond lengths (A)
Bong angles (ꢀ)
ligand 5b:
51% yield
95:5 dr
ligand 5b:
41% yield
99:1 dr
Ag(1)eO(1)
Ag(1)eO(2)
Ag(1)eP(1)
P(1)eC(34)
P(1)eC28
2.203(4)
2.568(6)
2.3553(9)
1.818(4)
1.827(3)
1.834(4)
1.378(5)
1.513(4)
1.384(5)
1.520(5)
1.503(6)
1.533(8)
O(1)eAg(1)eP(1)
O(1)eAg(1)eO(2)
P(1)eAg(1)eO(2)
P(1)eAg(1)eC(40)
O(2)eAg(1)eC(40)
C(34)eP(1)eC(28)
C(34)eP(1)eC(1)
C(28)eP(1)eC(1)
C(34)eP(1)eAg(1)
C(28)eP(1)eAg(1)
C(1)eP(1)eAg(1)
C(12)eC(21)eC(22)
167.36(14)
54.17(19)
136.89(13)
163.65(19)
27.2(2)
104.88(17)
103.59(17)
105.04(16)
116.81(13)
107.87(12)
117.41(11)
114.2(3)
MeO
HN
MeO
45%ee
38%ee
HN
ligand 5c:
53% yield
94:6 dr
ligand 5c:
38% yield
99:1 dr
P(1)eC(1)
C(1)eC(2)
30%ee
O
15%ee
ligand 5d:
56% yield
96:4 dr
ligand 5d:
50% yield
99:1 dr
C(2)eC(11)
C(11)eC(12)
C(12)eC(21)
C(21)eC(22)
C(40)eC(41)
O
7m
30%ee
7o
5%ee
Scheme 3. Ag-catalyzed asymmetric vinylogous Mannich-type reaction of trime-
thylsiloxyfuran and aldimines.

L.-S. Zheng et al. / Tetrahedron 69 (2013) 8777e8784
8781
The electronic UVevis spectra of monophosphine ligand 5a and
its silver complex show a major * transition at about 236 nm
due to naphthyl groups (see Supplementary data, Fig. S5). Upon the
molecular interaction between silvere5a complex and substrate,
different changes in UVevis absorption peak appear to be assigned
from chiral Ar-BINMOLs. The novel and air-stable monophosphines
(Ar-NNPs) featured with single phosphine-based binding site and
an additional benzyl group was synthesized in gram scale in high
yields. Furthermore, we evaluated the enantioselective activity of
these chiral monophosphines in asymmetric vinylogous Mannich-
type reaction. The enantioselective Ag-catalyzed vinylogous
Mannich-type reaction of trimethylsiloxyfuran with aldimines was
proved to a practical and efficient procedure in the presence of
chiral monophosphine, as the reaction proceed with excellent
yields (up to 99% isolated yields) and exceptional diaster-
pep
to the possible
addition of aldimine 6a, naphthyl
p
e
p
stacking of aromatic rings. Especially for the
* transition has red-shifted
pep
by 27 nm, while the use of trimethylsiloxyfuran resulted in
slightly blue-shifted by 6 nm. Similarly, in fluorescence emission
(FL) spectra of the silver complex and the reaction mixture (see
Supplementary data, Fig. S6), the emission band (lmax¼258 and
310 nm) of silvere5a complex dramatically decreased due to the
intermolecular interaction between 6a and silvere5a complex.
Thus on the basis of reaction data and spectroscopy analysis, we
proposed a preliminary mechanistic process for Ag/Ph-NNP 5a
complex-catalyzed vinylogous Mannich-type reaction in Scheme 4.
As shown in Scheme 4, the interaction of phosphine ligand 5a and
silversaltledtotheformationofsilvere5acomplex(S-I). And then the
silver complex could activate the electrophilic activity of aldimine by
silverenitrogen coordination (S-II). Meanwhile, the formation of in-
termediate S-III was facilitated by desilylation with aid of the i-PrOH
or other nucleophilic reagent. The key feature in our catalyst system
that is different from bidentate N,P-ligand maybe exist a possible
steric repulsion and aromatic interaction17 between substrate (aro-
matic imine) and silverephosphine complex, in which the benzyl
group on chiral monophosphine provides possibly dual function with
eoselectivity (>99:1 dr). The enantiomeric excesses of desired g-
butenolide derivatives were also promising and could reach mod-
erate to good level (up to 89:11 er), which offered a simple and
unprecedented example that axially chiral monophosphine with-
out additional heteroatom-donating group could exhibit good
enantiocontrol and high catalytic performances in silver-catalyzed
asymmetric vinylogous Mannich-type reaction. Further modifica-
tion of the new axially chiral monophosphine ligands for stereo-
selective vinylogous Mannich-type reaction and other
transformations to the synthesis of useful molecules is the focus of
our ongoing studies in the near future.
4. Experimental section
4.1. General
weak silverep/pe
p
stacking18 and steric repulsion to favour the
Flash column chromatography was performed over silica
(200e300 mesh). 1H NMR, and 13C NMR were recorded at 400 and
100 MHz, respectively, on Advance (Bruker) 400 MHz Nuclear
Magnetic Resonance Spectrometer, and were referenced to the in-
ternal solvent signals. Thin layer chromatography was performed
using silica gel; F254 TLC plates and visualized with ultraviolet light.
HPLC was carried out with a Waters 2695 Millennium system
equipped with a photodiode array detector. EI and CI mass spectra
were performed on a Trace DSQ GC/MS spectrometer. Data are re-
ported in the form of (m/z). The substrates including i-butyllithium
were commercial available and used directly. The Ar-BINMOLs 1 and
most of products 7 were known and confirmed by usual spectral
methods (1H NMR, 13C NMR, IR). The ESI-MS analysis of the samples
was operated on an LCQ advantage mass spectrometer (Thermo-
Fisher Company, USA), equipped with an ESI ion source in the
positive ionization mode, with data acquisition using the Xcalibur
software (Version 1.4). DCM was dried and distilled over CaH2. THF
and Et2O were distilled from sodium benzophenone ketyl. X-ray
diffraction: data sets were collected with Bruker APEX DUO and
Bruker APEX-II CCD diffractometers. Programs used: data collection
Bruker APEX2,19a data reduction Bruker SAINT, absorption correc-
tion for multi-scan, structure solution SHELX-97,19b structure re-
finement SHELXL-97,19b graphics Bruker SHELXTL.19b
diastereoselective Re-nucleophilic addition of siloxyfuran to imine.
Si
O
P
OH
AgOAc
O
or other Nu-
5a
Ph
Ph
P
O
Ag
Nu
O
Me
O
Si
Si
O
silver complex (S-I)
O
O
O
S-III(b)
S-III(a)
Ph
O
Ph
N
Ag
Me
N
O
P
6a
S-II
4.2. General procedure for the synthesis of ligands 5aed
mechanistic model
silver complex
(S-I)
4.2.1. Typical procedure for the synthesis of 2. To a solution of 1a
(7.52 g, >99%ee, 20 mmol) and NaI (17.8 g, 120 mmol) in dry ace-
tonitrile (100 mL) was added TMSCl (10.3 mL, 120 mmol) at room
temperature under Argon atmosphere. After the addition, the so-
lution was allowed to stir at room temperature overnight. Then
saturated sodium thiosulfate solution was added until the mixture
turned colourless. The resultant mixture was extracted with EtOAc,
and washed with water and saturated NaCl solution. The organic
layer was dried over Na2SO4, concentrated, and the residue was
purified by column chromatography (hexanes/ethyl acetate¼5:1)
to give 2a14 (7.13 g, >99% yield).
HN
Ph
O
Ag
P
(S)
(R)
Ph
(Z)
O
N
O
O
pi-pi stacking
anti-7a
S-IV
Scheme 4. Proposed mechanistic process for Ag-catalyzed vinylogous Mannich-type
reaction.
3. Conclusions
In summary, we have reported a simple procedure for the syn-
thesis of a new family of axially chiral monophosphines derived
4.2.1.1. (R)-20-(2-Methoxybenzyl)-[1,10-binaphthalen]-2-ol
(2b). Yield 99%, white solid. 1H NMR (400 MHz, CDCl3):
d
¼7.96 (dd,

8782
L.-S. Zheng et al. / Tetrahedron 69 (2013) 8777e8784
J¼7.2, 2.8 Hz, 1H), 7.93e7.89 (m, 3H), 7.49e7.43 (m, 2H), 7.40 (dd,
J¼8.8, 2.4 Hz, 1H), 7.38e7.34 (m, 1H), 7.30e7.24 (m, 3H), 7.20 (t,
J¼8.0 Hz, 1H), 7.06 (d, J¼8.8 Hz, 1H), 6.97 (d, J¼7.2 Hz, 1H),
6.87e6.79 (m, 2H), 5.19 (s, 1H), 3.84 (dd, J¼20.0, 4.0 Hz, 2H), 3.65 (d,
J¼11.2 Hz, 2H), 7.55 (d, J¼8.8 Hz, 1H), 7.52e7.48 (m, 1H), 7.41 (t,
J¼8.8 Hz, 2H), 7.30e7.21 (m, 3H), 7.08e7.05 (m, 2H), 6.81 (d, J¼7.6 Hz,
1H), 6.71e6.65 (m, 2H), 3.78 (dd, J¼33.6, 16.0 Hz, 2H), 3.51 (d,
J¼2.4 Hz, 3H) ppm; 13C NMR (100 MHz, CDCl3):
¼219.2, 157.3, 145.3,
d
J¼3.6 Hz, 3H) ppm; 13C NMR (100 MHz, CDCl3):
d
¼171.2 (EtOAc:
138.7, 133.7, 132.9, 132.5, 132.1, 130.9, 130.4, 129.6, 129.0, 128.6, 128.3,
128.1, 127.9, 127.8, 127.4, 127.2, 127.0, 126.2, 126.1, 125.4, 120.2, 119.5,
110.0, 55.0, 33.7 ppm; IR (neat): 3060, 3002, 2906, 2835, 1597, 1506,
1489, 1460, 1416, 1244, 1204, 1159, 1138, 1105, 1032, 970, 951, 943, 866,
831, 812, 754, 702, 673, 629, 615 cmꢁ1; HRMS (ESI) calcd For
C29H21F3NaO4S [MþNaþ]: 545.1005; Found: 545.1012.
CO), 157.3, 151.1, 140.2, 133.8, 133.2, 132.6, 131.2, 129.8, 129.1, 128.9,
128.6, 128.5, 128.0, 128.0, 127.6, 127.5, 126.7, 126.5, 125.8, 125.6,
124.8, 123.3, 120.4, 117.7, 110.4, 60.4 (EtOAc: CH2), 55.1, 34.1, 21.0
(EtOAc: COCH3), 14.2 (EtOAc: CH3) ppm; IR (neat): 3416, 3050,
2838,1693,1595,1493,1462,1377,1244,1167,1142,1111,1049,1028,
943, 816, 748, 708, 681, 663, 619 cmꢁ1; HRMS (ESI) calcd for
C28H22NaO2 [MþNa]þ: 413.1512; Found: 413.1514.
4.2.2.3. (R)-20-(4-Methylbenzyl)-[1,10-binaphthalen]-2-yl trifluoro-
methanesulfonate (3c). Yield 98%, white solid. 1H NMR (400 MHz,
4.2.1.2. (R)-20-(4-Methylbenzyl)-[1,10-binaphthalen]-2-ol
CDCl3):
d
¼8.04 (d, J¼9.2 Hz, 1H), 7.95 (d, J¼8.0 Hz, 1H), 7.92 (d,
(2c). Yield 99%, white solid. 1H NMR (400 MHz, CDCl3):
d¼7.90 (d,
J¼8.8 Hz, 1H), 7.88 (d, J¼8.4 Hz, 1H), 7.56 (dd, J¼8.8, 2.4 Hz, 1H),
7.54e7.50 (m, 1H), 7.44e7.40 (m, 2H), 7.31e7.20 (m, 3H), 7.08 (dd,
J¼8.4, 2.8 Hz, 1H), 6.90 (d, J¼7.6 Hz, 2H), 6.78 (d, J¼7.6 Hz, 2H), 3.73
(dd, J¼55.6, 15.6 Hz, 2H), 2.22 (s, 3H) ppm; 13C NMR (100 MHz,
J¼8.8 Hz, 1H), 7.88e7.84 (m, 3H), 7.46 (d, J¼8.4 Hz, 1H), 7.42 (t,
J¼7.2 Hz,1H), 7.32e7.28 (m, 2H), 7.25e7.21 (m, 2H), 7.18 (d, J¼6.4 Hz,
1H), 6.99 (d, J¼8.4 Hz, 1H), 6.92 (d, J¼8.0 Hz, 2H), 6.79 (d, J¼7.6 Hz,
2H), 4.70 (s, 1H), 3.70 (dd, J¼16.8, 15.6 Hz, 2H), 2.22 (s, 3H) ppm; 13C
CDCl3):
d¼145.1, 138.8, 136.9, 135.4, 133.6, 132.8, 132.4, 132.1, 130.5,
NMR (100 MHz, CDCl3):
d
¼151.1, 140.6, 137.2, 135.4, 133.6, 133.1,
129.4, 129.2, 129.0, 128.8, 128.6, 128.2, 127.9, 127.8, 127.6, 127.0, 126.9,
126.3, 126.0, 125.5, 119.4, 39.3, 20.9 ppm; IR (neat): 3060, 2931, 1609,
1510, 1414, 1246, 1215, 1140, 1065, 1030, 964, 939, 868, 833, 806, 754,
673, 631, 615 cmꢁ1; HRMS (ESI) calcd for C29H21F3NaO3S [MþNaþ]:
529.1056; Found: 529.1057.
132.6, 129.9, 129.2, 129.0, 128.9, 128.9, 128.6, 128.2, 128.1, 126.9, 126.6,
125.9, 125.7, 124.6, 123.4, 117.4, 117.2, 39.1, 20.9 ppm; IR (neat): 3530,
3483, 3053, 1616,1595, 1512, 1468, 1333, 1202,1167, 1140, 1126, 1022,
974, 847, 816, 762, 750, 679, 663, 625 cmꢁ1; HRMS (ESI) calcd for
C28H22NaO [MþNaþ]: 397.1563; Found: 397.1569.
4.2.2.4. (R)-20-(Naphthalen-2-ylmethyl)-[1,10-binaphthalen]-2-yl
4.2.1.3. (R)-20-(Naphthalen-2-ylmethyl)-[1,10-binaphthalen]-2-ol
trifluoromethanesulfonate (3d). Yield 97%, white solid. 1H NMR
(2d). Yield 99%, white solid. 1H NMR (400 MHz, CDCl3):
(400 MHz, CDCl3):
d
¼8.04 (dd, J¼8.8, 2.4 Hz,1H), 7.93e7.87 (m, 3H),
d
¼7.93e7.85 (m, 4H), 7.69 (d, J¼8.4 Hz, 1H), 7.58 (d, J¼4.0 Hz, 2H),
7.70e7.68 (m, 1H), 7.58e7.54 (m, 3H), 7.49e7.40 (m, 3H), 7.39e7.34
(m, 2H), 7.28e7.25 (m, 2H), 7.19 (d, J¼4.0 Hz, 2H), 7.13e7.04 (m, 2H),
4.00 (dd, J¼15.6, 6.0 Hz, 1H), 3.86 (dd, J¼15.6, 5.6 Hz, 1H) ppm; 13C
7.51e7.47 (m, 1H), 7.44e7.38 (m, 1H), 7.36 (t, J¼3.6 Hz, 2H),
7.31e7.24 (m, 5H), 7.19e7.14 (m, 1H), 7.02 (dd, J¼17.2 Hz, 2H), 4.74
(s, 1H), 3.88 (d, J¼6.4 Hz, 2H) ppm; 13C NMR (100 MHz, CDCl3):
NMR (100 MHz, CDCl3):
d¼145.2, 138.4, 137.5, 133.7, 133.6, 132.9,
d
¼151.0, 140.0, 137.6, 133.5, 133.3, 133.1, 132.6, 131.8, 130.0, 129.2,
132.5, 132.3, 132.0, 130.7, 129.5, 129.4, 129.0, 128.2, 128.1, 128.0,
127.9, 127.7, 127.6, 127.5, 127.1, 126.9, 126.5, 126.1, 125.9, 125.7, 125.3,
119.6, 40.1 ppm; IR (neat): 3060, 2912, 1615, 1508, 1414, 1246, 1232,
1213, 1171, 1151, 1138, 1065, 937, 868, 831, 812, 768, 754, 744, 673,
662, 631, 613 cmꢁ1; HRMS (ESI) calcd for C32H21F3NaO3S [MþNaþ]:
565.1056; Found: 565.1073.
129.0, 128.9, 128.2, 128.0, 127.8, 127.5, 127.4, 126.9, 126.6, 125.9,
125.7, 125.1, 124.5, 123.4, 117.4, 117.1, 39.7 ppm; IR (neat): 3517,
3053, 2856, 2924, 1620, 1595, 1506, 1468, 1435, 1379, 1310, 1269,
1202, 1171, 1142, 1126, 937, 901, 891, 858, 812, 787, 744, 642,
619 cmꢁ1; HRMS (ESI) calcd for C31H22NaO [MþNa]þ: 433.1563;
Found: 433.1575.
4.2.3. Typical procedure for the synthesis of 4. To a Schlenk flask
charged with 3a (4.92 g, 10 mmol), diphenylphosphine oxide
(4.04 g, 20 mmol), Pd(OAc)2 (0.112 g, 0.5 mmol) and dppb (0.213 g,
0.5 mmol) in DMSO (45 mL) was added DIEA (5.15 g, 7.0 mL,
40 mmol) under argon. The resulting mixture was stirred at 100 ꢀC
for 60 h. Then the mixture was cooled to room temperature, diluted
with EtOAc (100 mL), washed with water (40 mLꢂ3), brine (50 mL),
successively. The organic phase was dried over anhydrous Na2SO4,
filtered, concentrated, and the crude residue was filtrated through
a short silica gel column and flushed with petroleum ether/ethyl
acetate (3:1, v/v). The filtrate was concentrated under reduce
pressure, and a yellow solid 4a (3.54 g, 65% yield) was obtained and
used for the next step without further purification.
4.2.2. Typical procedure for the synthesis of 3. A single necked flask
charged with a solution of 2a (5.4 g, 15 mmol) and Et3N (4.55 g,
6.3 mL, 45 mmol) in CH2Cl2 (50 mL) was cooled to ꢁ78 ꢀC, and Tf2O
(5.07 g, 5.73 mL, 18 mmol) was added dropwise. Then the resulting
mixture was warmed to 0 ꢀC for 2 h. After removal of the solvent
under vacuum, the resulting thick residue was purified by flash
chromatography on silica gel (petroleum ether/ethyl acetate¼10:1,
v/v) to afford the desired product 3a as a white solid (7.08 g, >96%
yield).
4.2.2.1. (R)-20-Benzyl-[1,10-binaphthalen]-2-yl trifluoromethanesu-
lfonate (3a). Yield 98%, white solid. 1H NMR (400 MHz, CDCl3):
d
¼8.04 (d, J¼9.2 Hz, 1H), 7.93 (dd, J¼10.0, 8.4 Hz, 2H), 7.87 (d,
To a dried Schlenk flask charged with the above product (2.72 g,
5 mmol) in dry toluene (100 mL), Et3N (3.54 g, 4.96 mL, 35 mmol)
and HSiCl3 (3.38 g, 2.53 mL, 25 mmol) were added successively
under argon at 0 ꢀC. The resulting mixture was stirred at 100 ꢀC for
18 h. After cooled to 0 ꢀC, diluted by Et2O (50 mL), quenched with
saturated Na2CO3 solution, the mixture was filtered by a short
Celite column, and washed with Et2O (30 mLꢂ3). The filtrate was
dried over anhydrous Na2SO4, filtered, concentrated, and the resi-
due was purified by flash chromatography on silica gel (petroleum
ether/ethyl acetate¼20:1, v/v) to afford the desired product 5a as
a white solid (2.51 g, >95% yield).
J¼8.0 Hz, 1H), 7.56 (d, J¼9.2 Hz, 1H), 7.50 (t, J¼7.6 Hz, 1H), 7.44e7.40
(m, 2H), 7.30e7.23 (m, 2H), 7.20e7.18 (m, 1H), 7.11e7.05 (m, 4H), 6.89
(d, J¼2.0 Hz, 1H), 6.87 (s, 1H), 3.77 (dd, J¼54.4, 15.6 Hz, 2H) ppm; 13C
NMR (100 MHz, CDCl3):
d¼145.2, 140.1, 138.5, 133.6, 132.9, 132.5,
132.2, 130.6, 129.4, 129.3, 129.2, 128.8, 128.2, 128.0, 127.9, 127.7, 127.1,
126.9, 126.5, 126.1, 126.0, 125.6, 119.5, 39.8 ppm; IR (neat): 3059,
2926, 2856, 1596,1508,1495, 1418,1248,1207, 1171, 1138, 1065, 1028,
939, 864, 831, 808, 775, 744, 717, 698, 677, 631, 604 cmꢁ1; HRMS (ESI)
calcd for C28H19F3NaO3S [MþNa]þ: 515.0899; Found: 515.0913.
4.2.2.2. (R)-20-(2-Methoxybenzyl)-[1,10-binaphthalen]-2-yl trifluoro-
methanesulfonate (3b). Yield 96%, white solid. 1H NMR (400 MHz,
CDCl3):
4.2.3.1. (R)-(20-Benzyl-[1,10-binaphthalen]-2-yl)diphenylphos-
d¼8.02 (d, J¼8.8 Hz, 1H), 7.94 (d, J¼8.0 Hz, 1H), 7.88 (t,
phine (5a). Yield 95%; white solid; mp: 199e200 ꢀC; 1H NMR

L.-S. Zheng et al. / Tetrahedron 69 (2013) 8777e8784
8783
(400 MHz, CDCl3):
d
¼7.90e7.80 (m, 4H), 7.49e7.44 (m, 2H),
wasaddedfreshlydistilledCH2Cl2 (1.0 mL)underargon. Theresulting
mixture was stirred for 30 min at room temperature, and then imine
6a (0.25 mmol) in CH2Cl2 (0.8 mL) was added to the mixture followed
7.32e7.28 (m, 4H), 7.25e7.23 (m, 3H), 7.19 (t, J¼8.0 Hz, 3H), 7.13 (t,
J¼7.2 Hz, 2H), 7.08e6.97 (m, 6H), 6.83 (t, J¼7.6 Hz, 3H), 3.51 (dd,
J¼21.2, 16.0 Hz, 2H) ppm; 13C NMR (100 MHz, CDCl3):
d¼144.6,
by isopropanol (28 mL) and 2-(trimethylsilyloxy)furan (61.2 mL,
144.3,140.4, 138.1,137.4, 137.3,135.5, 135.4,135.3,133.7,133.7, 133.5,
133.5, 133.2, 133.0, 132.9, 131.9, 130.5, 129.5, 128.5, 128.4, 128.4,
128.2, 128.1, 128.0, 127.9, 127.8, 127.3, 127.0, 126.9, 126.6, 126.5,
0.375 mmol) when the mixture was cooled to ꢁ78 ꢀC. And the re-
action mixturewasstirred atꢁ78ꢀC for 10 h andthe resulted mixture
was also warmed to room temperature for the next 4 h. The reaction
was quenched by the addition of saturated aqueous solution of
NaHCO3. After stirring for 15 min at room temperature, the mixture
was extracted with CH2Cl2, washed with brine, and the combined
organic layer was dried over anhydrous Na2SO4. The solvent was
removed under reduced pressure and residue was purified by flash
column chromatography to give the corresponding product 7a
(65.6 mg, 99% yield, 76%ee).
125.8, 125.1, 39.7 ppm; 31P NMR (162 MHz, CDCl3):
d¼ꢁ14.40 ppm;
IR (neat): 3050, 1495, 1479, 1433, 1024, 961, 866, 829, 820, 808, 762,
744, 717, 692, 633, 619 cmꢁ1; HRMS (ESI) calcd for C39H29NaP
[MþNa]þ: 551.1899; Found: 551.1892. HPLC with a Chiralcel OD-H
column
(
l
¼254 nm; eluent: Hexane/Isopropanol¼95:5; Flow
rate: 0.8 mL/min; tmajor¼5.399 min; ee %¼99.9%).
4.2.3.2. (R)-(20-(2-Methoxybenzyl)-[1,10-binaphthalen]-2-yl)di-
phenylphosphine (5b). Yield 96%; white solid; mp: 102e103 ꢀC; 1H
4.3.1. (S)-2-((R)-Phenyl(phenylamino)methyl)furan-3(2H)-one
20
NMR (400 MHz, CDCl3):
d¼7.88e7.80 (m, 4H), 7.48 (dd, J¼8.8,
(7a). Yield 99%; white solid; mp: 129e132 ꢀC; [
a
]
ꢁ106.0 (c 1.1,
D
2.8 Hz, 1H), 7.45e7.41 (m, 1H), 7.28e7.22 (m, 7H), 7.19e7.16 (m, 3H),
7.12 (t, J¼7.2 Hz, 2H), 7.05 (t, J¼7.6 Hz, 3H), 6.95 (t, J¼7.6 Hz, 1H),
6.79 (d, J¼8.8 Hz,1H), 6.73 (d, J¼7.2 Hz,1H), 6.67e6.63 (m, 2H), 3.59
(dd, J¼30.8, 15.6 Hz, 2H), 3.52 (s, 3H) ppm; 13C NMR (100 MHz,
CHCl3); 1H NMR (400 MHz, CDCl3):
d
¼7.37e7.25 (m, 6H), 7.12 (t,
J¼7.2 Hz, 2H), 6.72 (t, J¼7.2 Hz, 1H), 6.57 (d, J¼7.6 Hz, 2H), 6.05 (dd,
J¼5.6, 2.0 Hz, 1H), 5.44 (dd, J¼4.0, 2.0 Hz, 1H), 4.86 (d, J¼4.0 Hz, 1H),
4.44 (s, 1H) ppm; 13C NMR (100 MHz, CDCl3):
d
¼172.4, 153.2, 146.0,
CDCl3):
d
¼157.5, 145.0, 144.7, 138.1, 137.9, 137.7, 137.6, 135.7, 135.6,
136.9, 129.3, 128.9, 128.3, 127.2, 123.2, 118.6, 114.0, 85.2, 59.4 ppm;
IR (neat): 3408, 3357, 1749, 1601, 1508, 1497, 1452, 1312, 1248, 1161,
1105, 1043, 932, 905, 810, 754, 725, 694, 611 cmꢁ1; MS (ESI): m/z:
266 [MþH]þ; Enantiomeric excess was determined by HPLC with
135.4, 133.9, 133.7, 133.6, 133.4, 133.2, 133.0, 131.9, 131.3, 130.6,
128.7,128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8, 127.7, 127.3, 127.2,
127.2, 126.9, 126.6, 126.2, 125.6, 124.9, 120.2, 110.1, 55.0, 33.9 ppm;
31P NMR (162 MHz, CDCl3):
d
¼ꢁ14.20 ppm; IR (neat): 3042, 2931,
a
Chiralcel OD-H column
(l
¼254 nm; eluent: Hexane/Iso-
2828, 1590, 1486, 1467, 1428, 1242, 1151, 1113, 1049, 1016, 816, 746,
687, 629 cmꢁ1; HRMS (ESI) calcd for C40H31NaOP [MþNa]þ:
581.2005; Found: 581.2008.
propanol¼80:20; Flow rate: 1.0 mL/min; tmajor¼23.335 min,
tminor¼33.090 min; ee %¼76%).
Acknowledgements
4.2.3.3. (R)-(20-(4-Methylbenzyl)-[1,10-binaphthalen]-2-yl)diphe-
nylphosphine (5c). Yield 98%; white solid; mp: 122e123 ꢀC; 1H
Financial support by the National Natural Science Foundation of
China (NSFC, Nos. 21173064 and 51203037), Program for Excellent
Young Teachers in Hangzhou Normal University (HNUEYT, JTAS
2011-01-014) and Zhejiang Provincial Natural Science Foundation
of China (Q12B020037), is appreciated. X.L.W. thank Prof. G.Q. Lai,
Prof. J.X. Jiang, Dr. Y. Deng, Ms. F.E. Zhu, Dr. K.Z. Jiang and Dr. C.Q.
Sheng of HZNU for X-ray crystallographic, NMR, IR and ESI-MS
measurements.
NMR (400 MHz, CDCl3):
d
¼7.95e7.86 (m, 4H), 7.54e7.50 (m, 2H),
7.37e7.24 (m, 10H), 7.19 (t, J¼7.6 Hz, 2H), 7.10 (t, J¼7.2 Hz, 2H), 7.04
(t, J¼7.6 Hz, 1H), 6.95e6.88 (m, 3H), 6.77 (d, J¼8.0 Hz, 2H), 3.54 (dd,
J¼21.2, 15.6 Hz, 2H), 2.27 (s, 3H) ppm; 13C NMR (100 MHz, CDCl3):
d
¼144.8, 144.5, 138.4, 137.8, 137.7, 137.6, 137.4, 135.8, 135.7, 135.5,
135.4, 135.3, 133.9, 133.8, 133.8, 133.7, 133.6, 133.5, 133.2, 133.1,
132.0, 130.6, 129.5, 129.0, 128.6, 128.5, 128.4, 128.4, 128.3, 128.3,
128.1, 127.9, 127.5, 127.0, 126.8, 126.6, 125.9, 125.2, 39.4, 21.1 ppm;
31P NMR (162 MHz, CDCl3):
d¼ꢁ14.34 ppm; IR (neat): 3044, 1510,
Supplementary data
1479,1433,1258,1180,1117,1090,1022, 860, 839, 816, 798, 789, 775,
743, 696, 633, 621, 613 cmꢁ1; HRMS (ESI) calcd for C40H31NaP
[MþNa]þ: 565.2056; Found: 565.2046.
Supplementary data of general remarks and the procedure of
the synthetic reaction, NMR data diagrams for all the products 2e7.
Supplementary data associated with this article can be found in the
online version, at http://dx.doi.org/10.1016/j.tet.2013.07.105.
4.2.3.4. (R)-(20-(Naphthalen-2-ylmethyl)-[1,10-binaphthalen]-2-
yl)diphenylphosphine (5d). Yield 96%; white solid; mp: 142e143 ꢀC;
1H NMR (400 MHz, CDCl3):
d¼7.99e7.88 (m, 4H), 7.77e7.76 (m, 1H),
References and notes
7.62e7.58 (m, 3H), 7.51e7.47 (m, 1H), 7.43e7.22 (m, 15H), 7.15 (d,
J¼6.4 Hz, 2H), 7.10e7.05 (m, 2H), 6.97 (s, 1H), 3.78 (s, 2H) ppm; 13C
1. Selected reviews: (a) Li, Z. G.; He, C. Eur. J. Org. Chem. 2006, 4313; (b) Yanagi-
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1191; (f) Valderas, C.; De la Torre, M. C.; Fernandz, I.; Munoz, M. P.; Sierra, M. A.
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Org. Chem. 1990, 55, 5935; (b) Yanagisawa, A.; Matsumoto, Y.; Nakashima, H.;
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K.; Hong, R. J. Am. Chem. Soc. 2012, 134, 4096.
NMR (100 MHz, CDCl3):
d
¼144.7, 144.3, 137.9, 137.7, 137.7, 137.6,
137.5, 135.7, 135.6, 135.6, 135.6, 133.8, 133.8, 133.7, 133.6, 133.5,
133.4, 133.1, 133.1, 132.0, 132.0, 130.6, 128.6, 128.5, 128.4, 128.3,
128.2, 128.1, 128.0, 127.9, 127.8, 127.7, 127.6, 127.5, 127.4, 127.0, 126.7,
126.5, 125.9, 125.7, 125.2, 40.0 ppm; 31P NMR (162 MHz, CDCl3):
d
¼ꢁ14.39 ppm; IR (neat): 3060, 2970, 2860, 1506, 1477, 1433, 1259,
1155, 1113, 1090, 1069, 1024, 866, 858, 812, 771, 741, 694, 644, 629,
611 cmꢁ1; HRMS (ESI) calcd for C43H32P [MþH]þ: 579.2236; Found:
579.2231.
3. Recent examples: (a) Fournier, J.; Lozano, O.; Menozzi, C.; Arseniyadis, S.; Cossy,
J. Angew. Chem., Int. Ed. 2013, 52, 1257; (b) Wang, W.; Kim, H.; Nam, S. J.; Rho, B.
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4.3. General procedure for the silver/Ph-NNP 5a complex-
catalyzed asymmetric vinylogous Mannich reactions with 2-
(trimethylsilyloxy)-furan
To
a dried Schlenk flask charged with AgOAc (2.2 mg,
0.0125 mmol) and chiral phosphine ligand 5a (6.6 mg, 0.0125 mmol),

8784
L.-S. Zheng et al. / Tetrahedron 69 (2013) 8777e8784
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ꢁ
ꢁ
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ꢁ
ꢁ
15. Reaction conditions: 6 mol % palladium(II) acetate, 6 mol % bis(diphenyl-
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