Chiral VAPOL Imidodiphosphoric Acid-Catalyzed Asymmetric Vinylogous Mannich Reaction for the Synthesis of Butenolides

Article abstract of DOI:10.1055/s-0037-1610232

Chiral butenolides were synthesized by the enantioselective vinylogous Mannich reaction. Chiral (VAPOL)-type imidodiphosphoric acids are efficient catalysts for the asymmetric vinylogous Mannich (AVM) reaction of aldimines and trimethylsiloxyfuran in toluene. Under the optimized conditions, a series of butenolides were obtained with high yields (up to 98%) and enantioselectivities (up to 97% ee) as well as excellent diastereoselectivities (up to 99:1 dr).

Full text of DOI:10.1055/s-0037-1610232

SYNLETT
0
9
3
6
-
5
2
1
4
1
4
3
7
-
2
0
9
6
© Georg Thieme Verlag Stuttgart · New York
2018, 29, A–E
letter
A
en
T. Zhou et al.
Letter
Synlett
Chiral VAPOL Imidodiphosphoric Acid-Catalyzed Asymmetric
Vinylogous Mannich Reaction for the Synthesis of Butenolides
Tianyun Zhoua,b
R
R
Jigang Gaoa
Guofeng Liua
Xukai Guana
Dong Ana
cat. 4 (5 mol%)
N
HN
OTMS
toluene, –40 °C
HP-b-CD
O
Ar
Ar
R = H, Cl, Br, Me, OMe
O
O
Suoqin Zhang*a,b
Guangliang Zhang*a
23 examples
32–98% yield
0–97% ee
O
OH
54:46 to 99:1 dr
a College of Chemistry, Jilin University, 2699 Qianjin Street,
Changchun 130012, P. R. of China
zhgl_jl@jlu.edu.cn
O
O
Ph
Ph
Ph
Ph
O
O
P
P
N
suoqin@jlu.edu.cn
b Key Laboratory for Molecular Enzymology and Engineering of
Ministry of Education, College of Life Sciences, Jilin University,
2699 Qianjin Street, Changchun 130012, P. R. of China
cat. 4
Received: 01.03.2018
Accepted after revision: 13.07.2018
Published online: 23.08.2018
via a cyclic transition state between the aldimine and the
catalyst (Scheme 1, a).13 However, it is hard to control the
selectivity of the reaction without the help of a neighboring
hydroxy group; the stereoselectivity of the reaction is diffi-
cult to control without a dual hydrogen-bonding inter-
action between the catalyst and 2-hydroxyphenyl aldimine.
Hence, the scope of substrates was limited. Recent reports
are focused on solving this problem in related Mannich re-
actions.14
DOI: 10.1055/s-0037-1610232; Art ID: st-2018-b0132-l
Abstract Chiral butenolides were synthesized by the enantioselective
vinylogous Mannich reaction. Chiral (VAPOL)-type imidodiphosphoric
acids are efficient catalysts for the asymmetric vinylogous Mannich
(AVM) reaction of aldimines and trimethylsiloxyfuran in toluene. Under
the optimized conditions, a series of butenolides were obtained with
high yields (up to 98%) and enantioselectivities (up to 97% ee) as well as
excellent diastereoselectivities (up to 99:1 dr).
a. Akiyama's work
Key words butenolides, trimethylsiloxyfuran, organocatalysis, enantio-
selectivity, asymmetric vinylogous Mannich reaction
HO
HO
HN
N
chiral phosphoric acid
γ-Butenolides1 are common structures widely present
in natural products, medicinal and biological chemistry.
Functional and chiral γ-butenolides exhibit various biologi-
cal activities.2–4 The asymmetric vinylogous Mannich reac-
tion is an important approach to synthesize γ-butenolides
bearing amine groups and two stereocenters.5–13 The first
AVM reaction between aldimine and 2-(trimethylsilyl-
oxy)furan was reported by Martin’s group in 1999.7 Subse-
quent studies focused on Lewis acid catalysis of this reac-
tion.8 In 2006, Hoveyda’s group reported an AVM reaction
catalyzed by a silver complex with excellent diastereo- and
enantioselectivity.9 In 2009 and 2013, Shi’s and Xu’s groups
applied chiral phosphine silver(I) to catalyze an AVM reac-
tion.10–12 Organocatalysis has also attracted considerable at-
tention in AVM reactions. In 2008, Akiyama et al. first re-
ported chiral phosphoric acid as a catalyst to synthesize
chiral γ-butenolides with good yields and stereoselectivi-
ties. The aldimine [2-(benzylideneamino)phenol] contain-
ing a 2-hydroxyphenyl moiety was used as an electrophile,
and the authors proposed that the AVM reaction proceeded
OTMS
O
O
O
b. This work
N
HN
chiral imidodiphosphoric acid
OTMS
O
O
O
Scheme 1 Chiral Brønsted acid-catalyzed asymmetric vinylogous
Mannich reaction
Chiral imidodiphosphoric acids are another kind of
chiral Brønsted acid catalysts. In 2012, imidodiphosphoric
acids were first reported by List and co-workers in asym-
metric spiroacetalization. Since then, those catalysts have
been efficient in many enantioselective reactions, such as
asymmetric Mannich reaction, asymmetric Friedel–Crafts
reaction, and asymmetric Pictet−Spengler reaction.15,16 In-
spired by previous works, we believe that chiral Brønsted
acids may be suitable catalysts for AVM reactions and pro-
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–E

B
T. Zhou et al.
Letter
Synlett
vide special chiral environments for the substrates. In this
report, we used chiral imidodiphosphoric acids as the cata-
lysts and chose 2-(trimethylsilyloxy)furan as the nucleo-
phile to attack aldimines without a neighboring hydroxy
group (Scheme 1, b). To begin the study, we investigated the
activity of catalysts 1–5 (Figure 1) in the reaction of aldi-
mine 6a and 2-(trimethylsilyloxy)furan 7.
selectivity in this reaction. For this reason, we selected
other types imidodiphosphoric catalysts for further study.
As shown in Table 1, entry 10, we found VAPOL-derived bis-
phosphorylated catalyst 4 to be the most effective for this
reaction. It provided the adduct with 92% yield in 65% ee.
VAPOL bisphosphorylated 5 could also give 92% yield, but
with a lower ee value (61% ee; Table 1, entry 11).
Ar2
Ar1
Table 1 Screening of Chiral Phosphoric Acids and Imidodiphosphoric
Acid Catalystsa
O
OH
O
O
O
O
P
P
N
O
O
O
P
OH
N
HN
Ar2
Ar1
cat.
2a: Ar1 = Ar2 = 2-naphthyl
2b: Ar1 = Ar2 = phenyl
OTMS
O
7
toluene, 0 °C
O
1
2c: Ar1 = Ar2 = 3,5-(CF3)2-phenyl
2d: Ar1 = phenyl, Ar2 = 2-naphthyl
2e: Ar1 = 1-naphthyl, Ar2 = 2-naphthyl
6a
8a
O
Entry
Catalyst
t (h)
Yield (%)b
ee (%)c
drc
Ar4
Ar3
1
2
1
24
60
48
6
52
63
70
75
61
41
74
58
70
92
92
10
rac
11
54:46
O
OH
O
O
O
O
P
P
2a
2b
2c
2d
2e
3a
3b
3c
4
54:46
56:44
77:23
53:47
90:10
91:9
N
3
Ar4
Ar3
4
−48
rac
11
3a: Ar3 = Ar4 = 2-naphthyl
3b: Ar3 = Ar4 = 3,5-(CF3)2-phenyl
5
10
10
16
12
10
13
13
3c: Ar3 = 3,5-(CF3)2-phenyl, Ar4 = 2-naphthyl
6
7
51
8
−60
27
80:20
74:26
92:8
O
OH
9
O
O
Ph
Ph
O
O
P
P
N
10
11
65
5
61
87:13
a Reaction conditions: aldimine 6a (0.1 mmol,1.0 equiv), 2-(trimethylsilyl-
oxy)-furan 7 (0.3 mmol, 3 equiv), catalyst (5 mol%), toluene (1 mL), 0 °C.
b Isolated yield.
5
O
c Enantiomeric excess of the major diastereomer; determined by high-
performance liquid chromatography (HPLC) analysis on a chiralcel OJ-H
column.
OH
O
O
Ph
Ph
Ph
Ph
O
O
P
P
N
Having identified the optimal catalyst 4 (Table 1, entry
10), we studied the effect of different solvents on the reac-
tion (Table 2, entries 1–8). As shown in Table 2, toluene
gave a better result (Table 2, entry 1). After raising the tem-
perature to 10 °C, the yield increased to 95%, but the ee
value decreased to 62% (Table 2, entry 9). When lowering
the temperature to −40 °C, an improved yield of 94% and
80% ee were observed (Table 2, entry 11).
Under the optimized conditions (Table 3, entry 6), we
examined a broad scope of aldimines with various kinds of
substituents. In Table 4, aldimines derived from aromatic
aldehydes, bearing a halogen group in para position of the
phenyl ring (Table 4, entries 2–4), such as 6b and 6c bearing
a fluorine and a chlorine group, respectively, gave the prod-
ucts 8b and 8c in high yields (98 and 97%) and enantio-
selectivities (85 and 80% ee ). Contrarily, 4-bromoaldimine
6d led to lower enantioselectivity (62% ee; Table 4, entry 4).
4
Figure 1 Chiral phosphoric acids and imidodiphosphoric acids
screened in the AVM reaction
As shown in Table 1, the yields increase from entry 1 to
5, but the enantioselectivities are still low. BINOL-type
catalysts 3a and 3b with similar substituents as those in 2a
and 2c, provided better yields (74 and 58%) and enantiose-
lectivities (51 and –60% ee; Table 1, entries 7 and 8). Inter-
estingly, when using catalysts 2c and 3b the sense of prod-
uct enantioselectivity could be switched. It was supposed
that the strong electron-withdrawing ability of the trifluoro-
methyl group leads to different directions of the chiral con-
trol of the catalyst to the substrate. Catalyst 3c, however,
gave only 70% yield and 27% ee (Table 1, entry 9). As a
whole, compared with chiral phosphoric acids, chiral imido-
diphosphoric acids were more suitable to control the stereo-
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–E

C
T. Zhou et al.
Letter
Synlett
Table 2 Optimization of the Solvent and Temperature for the AVM
Table 3 Optimization of the Catalyst Loading and Additive for the
AVM Reaction of Aldimines with 2-(Trimethylsilyloxy)furana
Reaction of Aldimines with 2-(Trimethylsilyloxy)furana
HN
N
HN
N
cat. 4
cat. 4, toluene
OTMS
OTMS
solvent
–40 °C, additive
O
O
O
O
6a
8a
6a
8a
7
7
O
O
Entry Solvent
T (°C)
t (h)
Yield (%)b ee (%)c drc
Entry
Additive (mg/mmol) t (h)
Yield (%)b ee (%)c
drc
1
2
toluene
o-xylene
m-xylene
mesitylene
ethylbenzene
anisole
0
0
13
5
92
92
88
92
57
89
62
45
95
92
94
94
57
65
60
57
60
47
45
31
8
92:8
1d
2e
3
none
15
15
15
15
15
10
89
87
86
86
86
97
75
72
70
71
72
80
89:11
90:10
90:10
91:9
none
91:9
3
0
10
12
12
7
3 Å MS (40)
4 Å MS (40)
5 Å MS (40)
HP-β-CD (40)
90:10
90:10
91:9
4
0
4
5
0
86:14
88:12
78:22
56:44
89:11
94:6
5
6
0
6
95:5
7
THF
0
14
14
7
a Reaction conditions: aldimine 6a (0.1 mmol, 1.0 equiv), 2-(trimethylsilyl-
oxy)-furan 7 (0.3 mmol, 3 equiv), toluene (1 mL), catalyst 4 (5 mol%),
−40 °C.
8
acetone
toluene
toluene
toluene
toluene
toluene
0
b Isolated yield.
9
10
−20
−40
−60
−78
62
74
80
79
31
c Enantiomeric excess of the major diastereomer; determined by HPLC
analysis on a chiralcel OJ-H column.
10
11
12
13
15
17
21
25
d Catalyst 4 (10 mol%).
e Catalyst 4 (3 mol%).
95:5
94:6
59:41
two substituents on the aldehyde’s phenyl ring were exam-
ined: 2,4-dichloro 6p gave 8p in excellent yield (97%) and
diasteroselectivity (99:1 dr; Table 4, entry 16). For 3,4-di-
chloro 6q, product 8q was obtained in good enantioselec-
tivity (90% ee), yield (90%), and diasteroselectivity (85:15
dr; Table 4, entry 17).
a Reaction conditions: aldimine 6a (0.1 mmol, 1.0 equiv), 2-(trimethylsilyl-
oxy)-furan 7 (0.3 mmol, 3 equiv), catalyst 4 (5 mol%), solvent (1 mL).
b Isolated yield.
c Enantiomeric excess of the major diastereomer; determined by HPLC
analysis on a chiralcel OJ-H column.
Substrate 6e with a 4-methyl group afforded the product in
87% yield with 84% ee (Table 4, entry 5). Changing the sub-
stituent to a 4-methoxy group, however, decreased the
yield to 67% and the ee value to 55% (Table 4, entry 6). In
summary, a stronger electron-donating capability of the
substrates involved much poorer yields and enantioselec-
tivities. Meta-methyl phenyl substrate 6h gave 8h with 64%
yield and 63% ee (Table 4, entry 8). Compound 6g with an
isopropyl group in para position gave only 55% yield and
82% ee (Table 4, entry 7). When a phenyl ring was changed
into a naphthyl ring, the corresponding products 8i and 8j
were obtained in poor enantioselectivities (Table 4, entries
9–10). Substrate 6k combined 4-fluoroaldehyde with 4-
methylaniline, and gave 8k with high enantioselectivity
and moderate diastereoselectivity (84% ee, 74:26 dr;
Table 4, entry 11).
Compounds 6l, 6m, and 6n, substituted with chlorine
atoms at different positions on the aniline’s phenyl ring
were separately studied (Table 4, entries 12–14). Meta-
chloro 6m gave 8m with a high yield (98%), 79% ee, and
84:16 dr (Table 4, entry 13). Contrarily, with use of ortho-
chloro 6l, the lowest ee was observed for 8l (Table 4, entry
12). Product 8o was obtained in 61% yield but no enantio-
selectivity was observed (Table 4, entry 15). Furthermore,
With 3,4-dichlorobenzaldehyde as a suitable moiety in
the substrates (Table 4, entry 17), different substituents on
the aniline were further studied (see results in Table 5).
Substrates 6r and 6s, substituted with bromo and methyl at
the para position, all gave good yields, excellent enantiose-
lectivities, and good diastereoselectivities (Table 5, entries
1–2). In particular, 8s was obtained in 97% yield, 96% ee,
and 85:15 dr (Table 5, entry 2). When substituted in meta
position, aldimines 6t–v gave the products in high yields
(90–98%) with excellent enantioselectivities and good dia-
stereoselectivities (96–97% ee, 81:19 dr, 80:20 dr, 84:16 dr;
Table 5, entries 3–5). In addition, when the phenyl group
was changed to naphthyl, the corresponding adduct 8w was
obtained with poor diastereoselectivity (55:45 dr) and
yield (Table 5, entry 6). We determined the absolute config-
uration of 8s as (R,S)-configuration by X-ray crystallograph-
ic analysis (Figure 2).17 The transition state of the reaction
was suggested on the basis of the product configuration
(see Supporting Information).
In conclusion, we have developed an AVM reaction for
aldimine and 2-(trimethylsilyloxy)furan using a VAPOL-
type chiral imidodiphosphoric acid as the catalyst.18 Under
the optimal reaction conditions, a variety of γ-butenolides
were prepared in high yields with excellent enantioselec-
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–E

D
T. Zhou et al.
Letter
Synlett
Table 4 Scope of Aldimines Having Different Substituents (Ar5 and R)
Table 5 Scope of Aldimines Having Different Substituents (Ar6) in the
in the AVM Reactiona
AVM Reactiona
R
Ar6
Ar6
N
HN
R
HN
cat. 4, toluene
cat. 4, toluene
N
O
OTMS
Ar5
Cl
O
Cl
OTMS
–40 °C, HR-β-CD
–40 °C, HR-β-CD
O
O
8r–w
Ar5
6r–w
O
Cl
7
Cl
6a–q
8a–q
7
O
Entry Product Ar6
t (h)
Yield (%)b ee (%)c drd
Entry Product Ar5
R
t (h) Yield (%)b ee (%)c drd
1
2
3
4
5
6
8r
4-BrC6H4
8
8
93
97
98
98
90
32
91
96
96
97
97
−
77:23
85:15
81:19
80:20
84:16
55:45
1
2
8a
8b
8c
8d
8e
8f
C6H5
H
10
6
97
98
97
91
87
67
55
64
72
87
85
74
98
87
61
97
90
80
85
80
62
84
55
82
63
66
64
84
15
79
60
rac
64
90
93:7
8s
8t
4-MeC6H4
3-ClC6H4
3-BrC6H4
3-MeC6H4
1-naphthyl
4-FC6H4
H
89:11
89:11
88:12
55:45
71:29
90:10
82:18
65:35
66:34
74:26
54:46
84:16
89:11
70:30
99:1
7
3
4-ClC6H4
4-BrC6H4
4-MeC6H4
4-MeOC6H4
4-i-PrC6H4
3-MeC6H4
2-naphthyl
1-naphthyl
4-FC6H4
H
7
8u
8v
8w
7
4
H
9
8
5
H
8
12
6
H
10
10
9
a Reaction conditions: aldimine 6r−w (0.1 mmol,1.0 equiv), 2-
(trimethylsilyloxy)-furan 7 (0.3 mmol, 3 equiv), toluene (1 mL), catalyst 4
(5 mol%), HP-β-CD (4 mg), −40 °C.
7
8g
8h
8i
H
b Isolated yield.
8
H
c Enantiomeric excess of the major diastereomer; determined by HPLC
analysis on OD-H and AD-H chiralcel columns.
d Determined by 1H NMR spectroscopy.
9
H
10
10
10
12
8
10
11
12
13
14
15
16
17
8j
H
8k
8l
4-Me
2-Cl
3-Cl
4-Cl
C6H5
tivities and diastereoselectivities. Notably, in our work, the
scope of substrates without a neighboring hydroxy group
was broadened, which is generally regarded as necessary
for good stereoselectivity. Further investigation of this reac-
tion and the application of those catalysts are under way in
our laboratory.
8m
8n
8o
8p
8q
C6H5
C6H5
11
C6H5
2-OMe 10
2,4-Cl2C6H3
3,4-Cl2C6H3
H
H
7
10
85:15
a Reaction conditions: aldimine 6a−q (0.1 mmol, 1.0 equiv), 2-(trimethylsilyl-
oxy)-furan 7 (0.3 mmol, 3 equiv), toluene (1 mL), catalyst 4 (5 mol%), HP-β-
CD (4 mg), −40 °C.
Funding Information
b Isolated yield.
c Enantiomeric excess of the major diastereomer; determined by HPLC analy-
sis on OD-H, OJ-H, and AD-H chiralcel columns.
d Determined by 1H NMR spectroscopy.
We are grateful for financial support from the National Natural
Science Foundation of China (Nos. 21372098 and 20802025) and the
Jilin Province Science & Technology Development Program (Nos.
20150203006GX and 20140307004GX).
N
oaitn
a
l
N
a
utarl
Secince
F
o
u
n
d
oaitn
of
C
h
n
i
a
2(
1
3
7
2
0
9
8
N)oaitn
a
l
N
a
utarl
Secince
F
o
u
n
d
oaitn
of
C
h
n
i
a
2(
0
8
0
2
0
2
5)
Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/s-0037-1610232.
S
u
p
p
ortiInfogrmoaitn
S
u
p
p
o
nrtogI
f
rmoaitn
References and Notes
(1) Langer, P. Synlett 2006, 3369.
(2) Kitani, S.; Miyamoto, K. T.; Takamatsu, S.; Herawati, E.; Igucgi,
H.; Nishitomi, K.; Uchida, M.; Nagamitsu, T.; Omura, S.; Ikeda,
H.; Nihira, T. Proc. Natl. Acad. Sci. USA 2011, 108, 16410.
(3) Lone, S. H.; Bhat, K. A.; Khuroo, M. A. Chem. Biol. Interact. 2015,
240, 180.
Figure 2 X-ray crystal structure of product 8s
(4) Ottow, E. A.; Brinker, M.; Teichmann, T.; Fritz, E.; Kaiser, W.;
Brosché, M.; Kangasjärvi, J.; Jiang, X.; Polle, A. Plant Physiol.
2005, 139, 1762.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–E

E
T. Zhou et al.
Letter
Synlett
(5) Mao, B.; Mastral, M. F.; Feringa, B. L. Chem. Rev. 2017, 117,
10502.
2014, 301. (h) Zhuo, M.-H.; Jiang, Y.-J.; Fan, Y.-S.; Gao, Y.; Liu, S.;
Zhang, S. Org. Lett. 2014, 16, 1096. (i) Liu, L.; Leutzsch, M.;
Zheng, Y.; Alachraf, M. W.; Thiel, W.; List, B. J. Am. Chem. Soc.
2015, 137, 13268. (j) An, D.; Zhu, Z.; Zhang, G.; Gao, Y.; Gao, J.;
Han, X.; Zheng, L.; Zhang, S. Tetrahedron: Asymmetry 2015, 26,
897. (k) Wu, K.; Zhuo, M. H.; Sha, D.; Fan, Y.-S.; An, D.; Jiang, Y.-J.;
Zhang, S. Chem. Commun. 2015, 51, 8054. (l) Xie, Y.; Cheng, G.-J.;
Lee, S.; Kaib, P. S. J.; Thiel, W.; List, B. J. Am. Chem. Soc. 2016, 138,
14538. (m) Zhuo, M. H.; Liu, G. F.; Song, S. L.; An, D.; Gao, J.;
Zheng, L.; Zhang, S. Adv. Synth. Catal. 2016, 358, 808. (n) An, D.;
Guan, X.; Guan, R.; Jin, L.; Zhang, G.; Zhang, S. Chem. Commun.
2016, 52, 11211. (o) Simón, L.; Paton, R. S. Org. Biomol. Chem.
2016, 14, 3031. (p) Das, S.; Liu, L.; Zheng, Y.; Alachraf, M. W.;
Thiel, W.; De, C. K.; List, B. J. Am. Chem. Soc. 2016, 138, 9429.
(q) Langdon, S. M. Tetrahedron 2016, 72, 5247. (r) Liu, G.; Zhuo,
M.; An, D.; Zhang, G.; Qin, X.; Gao, J.; Fan, S.; Zhang, S. Asian J.
Org. Chem. 2017, 6, 807. (s) Wang, C.; An, D.; Guan, X.; Fan, Y.;
Liu, G.; Zhang, G.; Zhang, S. Eur. J. Org. Chem. 2017, 1865.
(t) Tsuji, N.; Kennemur, J. L.; Buyck, T.; Lee, S.; Prévost, S.; Kaib,
P. S. J.; Bykov, D.; Farès, C.; List, B. Science 2018, 359, 1501.
(17) CCDC 1576505 (for 8t) contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre:
http://www.ccdc.cam.ac.uk/data_request/cif
(6) (a) Mandai, H.; Mandai, K.; Snapper, M. L.; Hoveyda, A. H. J. Am.
Chem. Soc. 2008, 130, 17961. (b) Zhao, Q.-Y.; Shi, M. Tetrahedron
2011, 67, 3724. (c) Shi, Y.-H.; Wang, Z.; Shi, Y.; Deng, W.-P. Tet-
rahedron 2012, 68, 3649. (d) Silverio, D. L.; Fu, P.; Carswell, E. L.;
Snapper, M. L.; Hoveyda, A. H. Tetrahedron Lett. 2015, 56, 3489.
(e) Rainoldi, G.; Sacchetti, A.; Silvani, A.; Lesma, G. Org. Biomol.
Chem. 2016, 14, 7768.
(7) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949.
(8) (a) Zhang, Q.; Hui, Y.; Zhou, X.; Lin, L.; Liu, X.; Feng, X. Adv. Synth.
Catal. 2010, 352, 976. (b) Zhou, L.; Lin, L.; Ji, J.; Xie, M.; Liu, X.;
Feng, X. Org. Lett. 2011, 13, 3056. (c) Ruan, S.-T.; Luo, J.-M.; Du,
Y.; Huang, P.-Q. Org. Lett. 2011, 13, 4938. (d) Ranieri, B.; Curti,
C.; Battistini, L.; Sartori, A.; Pinna, L.; Casiraghi, G.; Zanardi, F.
J. Org. Chem. 2011, 76, 10291.
(9) (a) Carswell, E. L.; Snapper, M. L.; Hoveyda, A. H. Angew. Chem.
Int. Ed. 2006, 45, 7230. (b) Yanagisawa, A.; Arai, T. Chem.
Commun. 2008, 1165.
(10) Yuan, Z.-L.; Jiang, J.-J.; Shi, M. Tetrahedron 2009, 65, 6001.
(11) Deng, H.-P.; Wei, Y.; Shi, M. Adv. Synth. Catal. 2009, 351, 2897.
(12) Zheng, L.-S.; Li, L.; Yang, K.-F.; Zheng, Z. J.; Xiao, X.-Q.; Xu, L.-W.
Tetrahedron 2013, 69, 8777.
(13) Akiyama, T.; Honma, Y.; Itoh, J.; Fuchibe, K. Adv. Synth. Catal.
2008, 350, 399.
(18) General Procedure for the Asymmetric Vinylogous Mannich
Reaction of Aldimines with 2-(Trimethylsilyloxy)furan
(14) (a) Hasegawa, A.; Naganawa, Y.; Fushimi, M.; Ishihara, K.;
Yamamoto, H. Org. Lett. 2006, 8, 3175. (b) Liu, H.; Dagousset, G.;
Masson, G.; Retailleau, P.; Zhu, J. J. Am. Chem. Soc. 2009, 131,
4598. (c) Zhou, F.; Yamamoto, H. Angew. Chem. Int. Ed. 2016, 55,
8970. (d) Zhou, F.; Yamamoto, H. Org. Lett. 2016, 18, 4974.
(15) For chiral phosphoric acids and their derivatives, see: (a) Liang,
Y.; Rowland, E. B.; Rowland, G. B.; Perman, J. A.; Antilla, J. C.
Chem. Commun. 2007, 4477. (b) Akiyama, T. Chem. Rev. 2007,
107, 5744. (c) Terada, M. Synthesis 2010, 1929. (d) Parmar, D.;
Sugiono, E.; Raja, S.; Rueping, M. Chem. Rev. 2014, 114, 9047.
(e) Parmar, D.; Sugiono, E.; Raja, S.; Rueping, M. Chem. Rev.
2017, 117, 10608.
(16) For chiral imidodiphosphoric acids, see: (a) Coric, I.; List, B.
Nature 2012, 483, 315. (b) Liao, S.; Čorić, I.; Wang, Q.; List, B. J. Am.
Chem. Soc. 2012, 134, 10765. (c) Chen, Y.-Y.; Jiang, Y.-J.; Fan, Y.-S.;
Sha, D.; Wang, Q.; Zhang, G.; Zheng, L.; Zhang, S. Tetrahedron:
Asymmetry 2012, 23, 904. (d) Kim, J. H.; Čorić, I.; Vellalath, S.; List,
B. Angew. Chem. Int. Ed. 2013, 52, 4474. (e) Wu, K.; Jiang, Y.-J.;
Sha, D.; Zhang, S. Chem. Eur. J. 2013, 19, 474. (f) Jindal, G.; Sunoj,
R. B. Angew. Chem. Int. Ed. 2014, 53, 4432. (g) An, D.; Fan, Y.-S.;
Gao, Y.; Zhu, Z. Q.; Zheng, L. Y.; Zhang, S. Q. Eur. J. Org. Chem.
A mixture of aldimine 6 (0.1 mmol), VAPOL imidodiphos-
phoric acid 4 (5 mol%) HP-β-CD (4 mg), toluene (1 mL) was
stirred at –40 °C for 15 min. Then, 2-(trimethylsilyloxy)furan 7
(0.3 mmol) was added under an argon atmosphere at –40 °C.
After the reaction was completed (monitored by TLC), the
mixture was purified by silica gel chromatography (ethyl
acetate/petroleum ether 1:6) to directly afford product 8.
(S)-5-[(R)-Phenyl(phenylamino)methyl]furan-2(5H)-one (8a)
20
Colorless oil, 97% yield, [α]D = –124.2 (c = 1.5, CHCl3), 80% ee,
93:7 dr [DaicelChiralcel OJ-H column, n-hexane/ethanol 80:20,
1.0 mL/min, λ = 254 nm, t(major) = 27.865 min, t(minor) =
1
32.746 min]. H NMR (400 MHz, DMSO-d6): δ = 7.81 (d, J = 8.0
Hz, 1 H),7.43 (d, J = 4.0 Hz, 2 H), 7.30 (t, J = 8.0 Hz, 2 H), 7.24–
7.21 (m, 1 H), 7.02 (t, J = 8.0 Hz, 2 H), 6.68 (d, J = 8.0 Hz, 2 H),
6.53 (t, J = 8.0 Hz, 1 H), 6.40 (d, J = 8.0 Hz, 1 H), 6.17–6.15 (m, 1
H), 5.50 (d, J = 4.0 Hz, 1 H), 4.90–4.87 (m, 1 H) ppm. 13C NMR
(100 MHz, DMSO-d6): δ = 173.1, 156.5, 147.7, 138.8, 129.2,
128.4, 128.3, 127.9, 122.2, 117.0, 113.7, 85.5, 58.6 ppm. HRMS
(ESI): m/z [M + H]+ calcd for C17H15NO2: 266.1103; found:
266.1188.
© Georg Thieme Verlag Stuttgart · New York — Synlett 2018, 29, A–E