Bismuth triflate as novel and efficient catalyst for the synthesis of β-aminosulfides

Article abstract of DOI:10.1055/s-2004-829144

Aziridines undergo ring opening readily with various thiols in the presence of 5 mol% bismuth triflate under very mild reaction conditions to afford the corresponding β-aminosulfides in excellent yields with high regioselectivity.

Full text of DOI:10.1055/s-2004-829144

1
854
PAPER
Bismuth Triflate as Novel and Efficient Catalyst for the Synthesis of
b-Aminosulfides
B
J
ismuth
T
h
riflate as
N
o
i
vel Cat
l
alyst fo
l
r
Synth
u
esis of
b
-Aminosu
S
lfides . Yadav,* B. V. Subba Reddy, Gakul Baishya, P. Venkatram Reddy, S. J. Harshavardhan
Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad-500 007, India
Fax +91(40)27160512; E-mail: yadav@iict.res.in, yadavpub@iict.res.in
Received 12 February 2004; revised 13 April 2004
tivity, low toxicity, moisture and air tolerance and their
recyclability make the use of lanthanide triflates attractive
alternatives to conventional Lewis acids. However, un-
Abstract: Aziridines undergo ring opening readily with various thi-
ols in the presence of 5 mol% bismuth triflate under very mild reac-
tion conditions to afford the corresponding b-aminosulfides in
excellent yields with high regioselectivity.
9
fortunately, lanthanide triflates are rather expensive and
thus their use in large-scale synthesis is limited. There-
fore, cheaper and more efficient catalysts are desirable. In
this direction, bismuth triflate has evolved as a remarkable
Lewis acid catalyst for effecting various organic transfor-
mations.10 Compared to lanthanide triflates, bismuth tri-
flate is inexpensive and easy to prepare on a multi-gram
scale in the laboratory from commercially available bis-
muth oxide and triflic acid.11 To the best of our know-
ledge, this is the first report on the use of bismuth triflate
as a catalyst for the activation of aziridines.
Key words: aziridines, metal triflates, thiols, b-aminosulfides
Aziridines are well known carbon electrophiles capable of
reacting with various nucleophiles and their ability to un-
dergo regioselective ring opening reactions contributes
1
largely to their synthetic value. They are useful interme-
diates for the synthesis of many biologically interesting
2
3
molecules such as amino acids, heterocycles and alka-
4
loids. Particularly, the cleavage of aziridines with thiols
In this article, we wish to highlight our results on the cat-
alytic application of bismuth triflate in the regioselective
ring opening reaction of aziridines with thiols. According-
ly, treatment of N-tosyl-2-phenyl aziridine with thionaph-
is interesting because the resultant b-aminosulfides are
important building blocks for the synthesis of various bio-
5
active molecules. The simple and most straightforward
route to b-aminosulfides involves the regioselective ring
thol in the presence of 5 mol% Bi(OTf) in MeCN at
opening of aziridines with thiols using acid or base catal-
3
6
ambient temperature resulted in the formation of b-ami-
nosulfide 2g in 91% yield (Scheme 1).
ysis. Lewis acids such as boron trifluoride etherate and
zinc chloride as well as Bronsted acids such as trifluo-
romethanesulfonic acid have been employed as acid cata-
In a similar fashion, N-benzyl- and N-tosyl-2-aryl aziri-
dines reacted smoothly with various thiols to afford the
corresponding b-aminosulfides in excellent yields. In the
cleavage of N-benzyl- and N-tosyl-2-aryl aziridines
6
,7
lysts. However, many of these procedures involve the
use of stoichiometric amount of catalysts, harsh condi-
tions and require large excess of thiols and necessitate an-
hydrous conditions to produce the desired products.
Furthermore, these reagents cannot be recovered and re-
cycled because they decompose or deactivate under
quenching conditions. Thus, no attempt has been made to
recycle the catalyst, thereby making the process economic
and environmental friendly. In fact, there is an advantage
in developing a catalytic process for the synthesis of b-
aminosulfides. Lanthanide triflates are unique Lewis ac-
(
Table 1, entries g–l), preferential cleavage at the benzylic
position of aziridine ring was observed while N-tosyl-2-
alkyl aziridines (Table 1, entries m–p) were cleaved clas-
sically at less hindered (terminal) aziridine-ring carbon.
Of course, cleavage reactions of both types of 2-aryl- and
2
-alkyl aziridines are stereoselective because only trans-
diastereomers of the corresponding regioisomers 2 and 3
were formed. In other words, 2-aryl substituted aziridines
expressed opposite regioselectivity when compared to 2-
8
ids that are currently of great interest. High catalytic ac-
Scheme 1
SYNTHESIS 2004, No. 11, pp 1854–1858
x
x.
x
x
.
2
0
0
4
Advanced online publication: 13.07.2004
DOI: 10.1055/s-2004-829144; Art ID: Z02804SS
Georg Thieme Verlag Stuttgart · New York
©

PAPER
Bismuth Triflate as Novel Catalyst for Synthesis of b-Aminosulfides
1855
alkyl aziridines while no regioselectvity was possible for give the corresponding b-aminosulfides 4 in high yields
the reactions of bicyclic aziridines. However, bicyclic-N- (Scheme 2).
tosyl aziridines underwent smooth cleavage with thiols to
Table 1 Metal Triflate-Catalyzed Synthesis of b-Aminosulfides from Aziridines
Entry Aziridine
Producta
5% Bi(OTf)3
Time (h)
5% Sc(OTf)3
Time (h)
Yield (%)b
92
Yield (%)b
90
a
4a
4b
4.5
7.0
b
5.5
89
87
85
90
6.0
87
85
83
89
c
d
e
4c
4d
4e
5.0
4.0
5.0
5.0
5.0
6.5
f
4f
5.5
3.0
85
6.0
3.5
81
g
2g
91 (6)
89 (8)
h
i
2h
2i
4.0
4.5
89 (5)
90 (7)
4.5
5.0
87 (6)
86 (9)
j
2j
6.0
4.0
85 (9)
92 (6)
6.5
4.5
82 (12)
90 (5)
k
2k
l
2l
5.5
90 (8)
5.5
87 (9)
m
n
3m
3n
5.0
5.5
89 (7)
86 (9)
6.0
6.5
83 (10)
82 (9)
Synthesis 2004, No. 11, 1854–1858 © Thieme Stuttgart · New York

1
856
J. S. Yadav et al.
PAPER
Table 1 Metal Triflate-Catalyzed Synthesis of b-Aminosulfides from Aziridines (continued)
Entry Aziridine
o
Producta
5% Bi(OTf)3
Time (h)
5% Sc(OTf)3
Time (h)
Yield (%)b
87 (6)
Yield (%)b
82 (11)
3o
3p
5.0
6.5
p
6.5
85 (5)
7.0
80 (12)
a
1
All products were characterized by H NMR, IR, and mass spectroscopy.
Yields reported in parentheses indicate other regioisomer.
b
tively. Further the scope and generality of this process is
illustrated with respect to various activated aziridines and
a wide variety of thiols and the results are presented in the
Table 1.
In summary, metal triflates are found to be useful and ef-
ficient alternatives to conventional Lewis acids for the re-
gioselective ring opening reactions of 2-phenyl- and 2-
alkyl-aziridines with thiols under mild conditions. The no-
Scheme 2
Except for the reactions of unsymmetrical aziridines such table features of this method are high conversions, greater
as styrene, octene and undecene aziridines, which produce regioselectivity, cleaner reaction profiles, operational
a minor amount of the other regioisomer (5–12%), the re- simplicity and reusability of the catalysts, which make it
actions of bicyclic aziridines were found to give exclu- useful and attractive strategy for the synthesis of b-amino-
sively product 4. Since bicyclic aziridines are sulfides.
symmetrical, no regioisomers were formed. In the case of
bicyclic aziridines, the stereochemistry of the ring opened
product 4a was found to be trans from the coupling con-
Melting points were recorded on Buchi R-535 apparatus and are un-
corrected. IR spectra were recorded on a Perkin-Elmer FT-IR 240-
1
stants of the ring hydrogens at d = 2.90 (ddd, J = 9.9, 9.5, c spectrophotometer using KBr optics. H NMR spectra were re-
1
4
.0 Hz, 1 H, -CHN), in H NMR spectrum. Similarly the corded on Gemini-200 spectrometer in CDCl using TMS as inter-
3
nal standard. Mass spectra were recorded on a Finnigan MAT 1020
mass spectrometer operating at 70 eV. TLC was monitored on 0.25
peak at d = 3.0 ppm for -CHS showed the similar splitting
pattern (ddd, J = 9.5, 9.5, 3.8 Hz, 1 H). Similarly N-Boc
aziridine also reacted smoothly with thiols to give the cor-
responding ring opened product in good yields (entries c
and d). The method is clean and highly regioselective, af-
mm Merck pre-coated silica gel plates (60F-254). Bi(OTf) was
3
1
1
prepared in our laboratory.
Synthesis of b-Amino Sulfide; General Procedure
fording b-aminosulfides in excellent yields. This method A mixture of N-activated aziridine (5 mmol), thiol (7.5 mmol) and
is even effective with alkyl thiols (entries d and j) for the Bi(OTf)
(5 mol%) or Sc(OTf)
was stirred at ambient temperature for the appropriate time
Table 1). After completion of the reaction as indicated by TLC, the
(5 mol%) in anhyd MeCN (10 mL)
3
3
synthesis of alkyl-substituted b-aminosulfides. The reac-
tion conditions are mild and no side products or decompo-
sition of the products was observed. All the products were
(
reaction mixture was quenched with water (10 mL) and extracted
with EtOAc (2 × 15 mL). The combined organic layers were dried
over anhyd Na SO , concentrated in vacuo and purified by column
1
fully characterized by mass spectrometry, H NMR and
2
4
1
3
IR, and C NMR spectroscopic data for new products.
chromatography on silica gel (Merck, 100-200 mesh, EtOAc–hex-
However, in the absence of catalyst, the reaction did not ane, 2:8) to afford pure b-amino sulfide. The aq layer was concen-
yield any product even after long reaction times (8–12 h). trated in vacuo to recover the catalyst for use in further runs. The
products thus obtained were identified by comparison of their
The efficacy of various metal triflates such as Bi(OTf)3,
NMR, IR, Mass, TLC, mixed TLC analysis and physical data with
Sc(OTf) , In(OTf) Yb(OTf) , Y(OTf) , Dy(OTf) and
3
3
3
3
3
authentic samples. The spectral data of all the products were identi-
Ce(OTf) was studied for this reaction. Among these met-
6,7
3
cal with those of authentic samples.
al triflates, 5 mol% bismuth and scandium triflates were
found to be more efficient catalysts in terms of conversion 4a
and reaction time. Compared to bismuth triflate, scandium White solid; mp 130–132 °C.
7
a
triflate was easily recovered from aqueous layer during
work-up. The recovered scandium triflate was reused in
subsequent reactions with gradual decrease in activity.
For instance, N-tosyl-2-phenyl aziridine and thiophenol
gave 90%, 86% and 79% yields over three cycles, respec-
IR (KBr): 3265, 2933, 2861, 1600 cm–1.
1
H NMR (200 MHz, CDCl ): d = 1.20–1.47 (m, 4 H), 1.50–1.75 (m,
3
2
H), 1.95–2.10 (m, 1 H), 2.20–2.30 (m, 1 H), 2.45 (s, 3 H), 2.90
(
ddd, J = 4.0, 9.5, 9.9 Hz, 1 H), 3.0 (ddd, J = 3.8, 9.5, 9.5 Hz, 1 H),
Synthesis 2004, No. 11, 1854–1858 © Thieme Stuttgart · New York

PAPER
Bismuth Triflate as Novel Catalyst for Synthesis of b-Aminosulfides
1857
–
1
5
.15 (br s, NH, 1 H), 7.20–7.40 (m, 7 H), 7.75 (d, J = 7.9 Hz, 2 H).
IR (KBr): 3300, 2927, 2838, 1610 cm .
+
EIMS: m/z = 361 [M ], 252, 206, 190, 91, 107, 81, 55.
1
H NMR (200 MHz, CDCl ): d = 2.40 (s, 3 H), 3.25–3.40 (m, 2 H),
.25 (t, J = 7.1 Hz, 1 H), 4.65 (br s, NH, 1 H), 7.10–7.35 (m, 8 H),
.40–7.60 (m, 4 H), 7.60–7.85 (m, 4 H).
3
4
7
4
b
Pale yellow solid; mp 115–116 °C.
1
3
1
C NMR ( H-decoupled, CDCl ): d = 21.3, 47.5, 53.0, 126.4,
26.5, 127.1, 127.5, 127.7, 128.0, 128.5, 128.9, 129.6, 130.8, 131.6,
–
1
3
IR (KBr): 3315, 2937, 2835, 1610 cm .
1
1
H NMR (200 MHz, CDCl ): d = 1.20–1.45 (m, 4 H), 1.50–1.65 (m,
132.7, 133.8, 137.6, 138.6, 143.4.
3
2
3
H), 1.95–2.10 (m, 1 H), 2.19–2.25 (m, 1 H), 2.45 (s, 3 H), 2.85–
.0 (m, 2 H), 5.20 (d, J = 7.0 Hz, 1 H, NH), 7.10 (d, J = 7.9 Hz, 2
+
FAB–MS: m/z = 433 [M ], 274, 263, 249, 185, 155, 128, 105, 91,
6
9, 55.
H), 7.25 (d, J = 8.0 Hz, 2 H), 7.38 (d, J = 8.0 Hz, 2 H) 7.70 (d, J =
7
.9 Hz, 2 H).
2
h
1
3
1
C NMR ( H-decoupled, CDCl ): d = 21.4, 23.0, 24.1, 31.1, 31.7,
Yellow solid; mp 140–142 °C.
IR (KBr): 3286, 2940, 2856, 1601 cm–1.
3
5
1.1, 54.9, 121.5, 127.1, 129.5, 131.9, 134.2, 137.4, 143.3.
+
FAB–MS: m/z= 440 [M ], 286, 269, 190, 136, 107, 81, 55.
1
H NMR (200 MHz, CDCl ): d = 2.20 (s, 3 H), 3.25–3.38 (m, 2 H),
3
4
.20 (t, J = 7.1 Hz, 1 H), 4.60 (br s, 1 H, NH), 7.10 (d, J = 8.0 Hz, 2
4
c
H), 7.15–7.20 (m, 2 H), 7.30–7.40 (m, 7 H), 7.65 (d, J = 8.0 Hz, 2
H).
7
a
Colorless solid; mp 109–111 °C.
–
1
IR (KBr): 3348, 2933, 2857, 1697, 1530 cm .
13
1
C NMR ( H-decoupled, CDCl ): d = 21.5, 46.9, 52.7, 127.0,
3
1
H NMR (200 MHz, CDCl ): d = 1.10–1.35 (m, 3 H), 1.39 (s, 9 H),
127.8, 128.2, 128.9, 129.7, 132.0, 132.1, 133.5, 134.0, 136.6, 137.8,
143.8.
3
1
.48–1.75 (m, 3 H), 1.95–2.05 (m, 1 H), 2.10–2.25 (m, 1 H), 2.80
(
1
dt, J = 3.8, 10.3 Hz, 1 H), 3.30–3.35 (m, 1 H), 4.70 (d, J = 7.5 Hz,
H, NH), 7.10–7.30 (m, 3 H), 7.35–7.48 (m, 2 H).
+
FAB–MS: m/z = 462 [M ], 307, 274, 212, 154, 109, 95, 69, 55.
+
FAB–MS: m/z = 307 [M ], 252, 190, 129, 115, 81, 57.
2i
7
a
Colorless liquid.
4
d
IR (KBr): 3313, 2938, 1598 cm–1.
7
a
White solid; mp 70–72 °C.
1
H NMR (200 MHz, CDCl ): d = 1.60 (br s, 1 H, NH), 2.35 (s, 3 H),
–
1
3
IR (KBr): 3357, 2935, 2839, 1689, 1525 cm .
3
.14 (d, J = 7.4 Hz, 2 H), 3.80 (s, 2 H), 4.20 (t, J = 7.1 Hz, 1 H), 4.50
1
H NMR (200 MHz, CDCl ): d = 1.15–1.30 (m, 3 H), 1.40 (s, 9 H),
(br s, 1 H, NH), 7.05 (d, J = 8.0 Hz, 2 H), 7.13 (d, J = 8.0 Hz, 2 H),
7.20–7.45 (m, 10 H).
3
1
.50–1.70 (m, 3 H), 1.97–2.10 (m, 1 H), 2.15–2.28 (m, 1 H), 2.45
(
4
dt, J = 3.7, 10.2 Hz, 1 H), 3.40–3.50 (m, 1 H), 3.60–3.75 (m, 2 H),
.60 (br s, NH, 1 H), 7.25–7.40 (m, 5 H).
+
FAB–MS: m/z= 334 [M ], 210, 120, 91, 77.
+
FAB–MS: m/z = 321 [M ], 265, 204, 130, 116, 82, 57.
2j
7
a
Oil.
4
e
IR (KBr): 3310, 2941, 2857, 1600 cm–1.
Pale yellow solid; mp 91–93 °C.
1
H NMR (200 MHz, CDCl ): d = 0.90 (t, J = 7.0 Hz, 3 H), 1.20–1.55
–
1
3
IR (KBr): 3370, 2927, 2830, 1605 cm .
(
m, 4 H), 2.10 (br s, 1 H, NH), 2.25–2.35 (m, 2 H), 3.05 (d, J = 7.3
1
H NMR (200 MHz, CDCl ): d = 1.40–1.57 (m, 2 H), 1.60–1.80 (m,
Hz, 2 H), 3.80 (s, 2 H), 4.0 (t, J = 7.3 Hz, 1 H), 7.15–7.45 (m, 10 H).
3
2
3
H), 1.95–2.20 (m, 2 H), 2.40 (s, 3 H), 3.20–3.30 (m, 1 H), 3.50–
.60 (m, 1 H), 5.60 (d, J = 7.0 Hz, NH, 1 H), 7.10 (d, J = 8.0 Hz, 2
+
FAB–MS: m/z = 299 [M ], 120, 91, 77, 43.
H), 7.20 (d, J = 7.9 Hz, 2 H), 7.30 (d, J = 8.0 Hz, 2 H) 7.65 (d, J =
2
k
7
.9 Hz, 2 H).
Colorless solid; mp 128–130 °C.
IR (KBr): 3280, 2951, 2837, 1598 cm–1.
1
3
1
C NMR ( H-decoupled, CDCl ): d = 21.5, 21.6, 30.2, 31.4, 52.3,
3
5
9.5, 120.9, 127.1, 129.6, 131.8, 133.6, 136.8, 143.5.
1
H NMR (200 MHz, CDCl ): d = 2.30 (s, 3 H), 2.45 (s, 3 H), 3.20–
+
3
FAB–MS: m/z = 427 [M ], 255, 238, 172, 155, 123, 109, 95, 83, 69,
5
3
7
.30 (m, 2 H), 4.25 (t, J = 7.0 Hz, 1 H), 4.65 (br s, 1 H, NH), 7.10–
5.
.30 (m, 8 H), 7.35–7.40 (m, 2 H), 7.60 (d, J = 8.0 Hz, 2 H).
1
3
1
C NMR ( H-decoupled, CDCl ): d = 21.0, 21.5, 47.0, 52.4, 127.0,
4
f
3
1
1
27.6, 129.0, 129.6, 129.7, 131.6, 133.7, 133.9, 134.7, 136.8, 138.1,
43.6.
Pale yellow solid; mp 130–131 °C.
–
1
IR (KBr): 3362, 2933, 2861, 1615 cm .
+
FAB–MS: m/z = 431 [M ], 288, 261, 154, 91, 69, 55.
1
H NMR (200 MHz, CDCl ): d = 1.39–1.58 (m, 2 H), 1.60–1.78 (m,
3
2
3
H), 1.97–2.21 (m, 2 H), 2.38 (s, 3 H), 3.30–3.35 (m, 1 H), 3.55–
.60 (m, 1 H), 5.75 (d, J = 7.0 Hz, NH, 1 H), 7.05 (d, J = 8.0 Hz, 2
2
l
Pale yellow solid; mp 125–126 °C.
H), 7.20–7.38 (m, 2 H), 7.45–7.58 (m, 3 H), 7.65–7.80 (m, 4 H).
–
1
IR (KBr): 3289, 2978, 2820, 1600 cm .
1
1
3
1
C NMR ( H-decoupled, CDCl ): d = 21.4, 21.7, 30.3, 31.6, 52.4,
9.7, 126.1, 126.5, 127.1, 127.4, 127.6, 128.3, 129.2, 129.5, 130.3,
31.7, 132.2, 133.6, 136.8, 143.2.
3
H NMR (200 MHz, CDCl ): d = 2.30 (s, 3 H), 2.45 (s, 3 H), 3.21–
.30 (m, 2 H), 4.10 (t, J = 7.0 Hz, 1 H), 4.60 (br s, 1 H, NH), 7.10–
.18 (m, 6 H), 7.20–7.30 (m, 4 H), 7.62 (d, J = 8.0 Hz, 2 H).
5
1
3
3
7
+
FAB–MS: m/z: 397 [M ], 243, 190, 185, 155, 127, 105, 69, 55.
1
3
1
C NMR ( H-decoupled, CDCl ): d = 21.0, 21.5, 47.0, 52.3, 121.9,
3
1
1
27.0, 127.6, 129.6, 129.7, 132.0, 132.3, 133.8, 134.6, 136.8, 138.1,
43.6.
2
g
Colorless solid; mp 137–138 °C.
Synthesis 2004, No. 11, 1854–1858 © Thieme Stuttgart · New York

1
858
J. S. Yadav et al.
PAPER
+
FAB–MS: m/z = 476 [M ], 293, 288, 274, 245, 221, 155, 131, 119,
Hz, 1 H), 3.15–3.40 (m, 2 H), 4.65–4.75 (m, 1 H, NH), 7. 0 (d, J =
1
05, 91, 69, 55.
8.0 Hz, 2 H), 7.25–7.80 (m, 9 H).
1
3
1
C NMR ( H-decoupled, CDCl ): d = 14.0, 21.2, 22.6, 25.2, 29.0,
3
3
m
2
1
9.3, 31.8, 33.6, 39.1, 52.9, 125.8, 126.5, 127.0, 128.4, 129.4,
31.8, 132.9, 133.7, 137.5, 143.1.
Oil.
–
1
IR (KBr): 3280, 2938, 2843, 1605 cm .
+
FAB–MS: m/z = 483 [M ], 313, 185, 174, 155, 91, 55.
1
H NMR (200 MHz, CDCl ): d = 0.81 (t, J = 7.0 Hz, 3 H), 1.10–1.30
m, 8 H), 1.35–1.60 (m, 2 H), 2.40 (s, 3 H), 2.60 (dd, J = 7.0, 10.3
Hz, 1 H), 3.0 (dd, J = 4.0, 10.3 Hz, 1 H), 3.20–3.35 (m, 1 H), 3.80
s, 3 H), 4.65 (dd, J = 4.0, 7.1 Hz, 1 H), 6.80 (d, J = 8.0 Hz, 2 H),
.20–7.35 (m, 4 H), 7.60 (d, J = 8.0 Hz, 2 H).
3
(
Acknowledgment
(
7
BVS thanks CSIR, New Delhi for the award of fellowship.
1
3
1
C NMR ( H-decoupled, CDCl ): d = 14.0, 21.4, 22.5, 25.2, 28.5,
3
3
1
1.6, 33.4, 39.7, 52.6, 55.1, 114.3, 122.7, 126.9, 129.5, 132.4, References
37.6, 144.2, 159.7.
(
1) (a) Katritzky, A. R.; Rees, C. W. Comprehensive
Heterocyclic Chemistry, Vol. 7; Pergamon Press: Oxford,
984, 47. (b) Kump, J. E. G. Comprehensive Organic
+
FAB–MS: m/z = 421 [M ], 268, 251, 153, 133, 109, 92, 75.
1
3
n
Synthesis, Vol. 7; Trost, B. M.; Fleming, I., Eds.; Pergamon
Press: Oxford, 1991, 469.
White solid; mp 58–59 °C.
–
1
(2) (a) Tanner, D. Angew. Chem., Int. Ed. Engl. 1994, 33, 599.
b) McCoull, W.; Davis, F. A. Synthesis 2000, 1347.
(3) (a) Dureault, A.; Tranchepain, I.; Depezay, J. C. J. Org.
Chem. 1989, 54, 5324. (b) Tanner, D.; He, H. M.
Tetrahedron 1992, 48, 6079.
IR (KBr): 3278, 2943, 2851, 1600 cm .
(
1
H NMR (200 MHz, CDCl ): d = 0.83 (t, J = 6.8 Hz, 3 H), 1.0–1.25
m, 8 H), 1.30–1.65 (m, 2 H), 2.40 (s, 3 H), 2.75 (dd, J = 7.0, 10.3
Hz, 1 H), 3.10–3.30 (m, 2 H), 4.85 (d, J = 7.0 Hz, 1 H, NH), 7.10–
.25 (m, 6 H), 7.60 (d, J = 8.0 Hz, 2 H).
3
(
7
(
4) Hudlicky, T.; Luna, H.; Price, J. D.; Rulin, F. J. Org. Chem.
1990, 55, 4683.
1
3
1
C NMR ( H-decoupled, CDCl ): d = 14.0, 21.4, 22.4, 25.1, 28.6,
1.5, 33.5, 39.6, 52.7, 127.0, 129.0, 129.5, 131.0, 132.1, 133.9,
3
3
1
(5) (a) Bae, J. H.; Shin, S. H.; Park, C. S.; Lee, W. K.
Tetrahedron 1999, 55, 10041. (b) Ingenitio, R.; Bianchi, E.;
Fattori, D.; Pessi, A. J. Am. Chem. Soc. 1999, 121, 11369.
37.6, 143.4.
+
FAB–MS: m/z = 426 [M ], 268, 255, 155, 136, 109, 91, 69, 55.
(
c) Adams, B.; Beresford, K. J. M.; Whyte, S. M.; Young, D.
W. J. Chem. Soc., Chem. Commun. 2000, 619.
6) (a) Carreaux, F.; Dureault, A.; Depezay, J. C. Synlett 1992,
3
o
(
Yellow solid; mp 74–76 °C.
527. (b) Maligres, P. E.; See, M. M.; Askin, D.; Reider, P. J.
–
1
IR (KBr): 3278, 2941, 2830, 1601 cm .
Tetrahedron Lett. 1997, 38, 5253.
1
(7) (a) Wu, J.; Hou, X. L.; Dai, L. X. J. Chem. Soc., Perkin
Trans. 1 2001, 1314. (b) Katagiri, T.; Takahashi, M.;
Fujiwara, Y.; Ihara, H.; Uneyama, K. J. Org. Chem. 1999,
H NMR (200 MHz, CDCl ): d = 0.80 (t, J = 6.8 Hz, 3 H), 0.95–1.35
m, 15 H), 1.55–1.65 (m, 1 H), 2.35 (s, 3 H), 2.80 (dd, 1 H, J = 7.0,
3
(
1
0.3 Hz), 3.10–3.30 (m, 2 H), 4.60 (d, J = 7.0 Hz, NH, 1 H), 7.10
d, J = 8.0 Hz, 2 H), 7.20 (d, J = 7.9 Hz, 2 H), 7.38 (d, J = 7.9 Hz, 2
H), 7.60 (d, J = 8.0 Hz, 2 H).
64, 7323. (c) Antolini, L.; Bucciarelli, M.; Caselli, E.;
(
Davoli, P.; Forni, A.; Moretti, I.; Prati, F.; Torre, G. J. Org.
Chem. 1997, 62, 8784.
1
3
1
C NMR ( H-decoupled, CDCl ): d = 14.0, 21.4, 22.6, 25.2, 29.0,
9.3, 31.8, 33.6, 39.5, 52.8, 120.3, 127.1, 129.5, 131.3, 132.0,
34.7, 137.8, 143.1.
3
(
8) (a) Imamoto, T. Lanthanides in Organic Synthesis;
Academic Press: London, 1994. (b) Molander, G. A. Chem.
Rev. 1992, 92, 29.
(9) (a) Kobayashi, S. Synlett 1994, 689. (b) Kobayashi, S. J.
Synth. Org. Chem., Jpn. 1995, 53, 370. (c) Kobayashi, S.
Eur. J. Org. Chem. 1999, 15.
2
1
+
FAB–MS: m/z = 512 [M ], 341, 310, 262, 203, 155, 122, 91, 69, 55.
3
p
Colorless solid; mp 66–67 °C.
(10) Leonard, M. N.; Wieland, L. C.; Mohan, R. S. Tetrahedron
2002, 58, 8373.
–
1
IR (KBr): 3280, 2945, 2842, 1603 cm .
(
11) Repichet, S.; Zwick, A.; Vendier, L.; Le Roux, C.; Dubac, J.
1
H NMR (200 MHz, CDCl ): d = 0.83 (t, J = 6.8 Hz, 3 H), 0.99–1.37
3
Tetrahedron Lett. 2002, 43, 993.
(
m, 15 H), 1.57–1.65 (m, 1 H), 2.30 (s, 3 H), 2.80 (dd, J = 7.0, 10.3
Synthesis 2004, No. 11, 1854–1858 © Thieme Stuttgart · New York