Indium tribromide catalyzed aminolysis of aziridines: An efficient synthesis of vicinal-diamines

Article abstract of DOI:10.1055/s-2002-31965

Indium tribromide catalyzes efficiently the aminolysis of activated aziridines with aromatic amines under mild reaction conditions to afford the corresponding vicinal-diamines in high yields with high selectivity.

Full text of DOI:10.1055/s-2002-31965

PAPER
1061
Indium Tribromide Catalyzed Aminolysis of Aziridines: An Efficient
Synthesis of vicinal-diamines
A
J
minolysi
.
s
of
a
ziridine
S
s
.Yadav,* B. V. S. Reddy, K. Vishweshwar Rao, K. Saritha Raj, A. R. Prasad
Organic Chemistry Division-1, Indian Institute of Chemical Technology, Hyderabad-500 007, India
Fax +91(40)7160512; E-mail: yadav@iict.ap.nic.in
Received 2 February 2002; revised 16 April 2002
Abstract: Indium tribromide catalyzes efficiently the aminolysis of
activated aziridines with aromatic amines under mild reaction con-
ditions to afford the corresponding vicinal-diamines in high yields
with high selectivity.
Key words: aziridines, indium reagents, aryl amines, vic-diamines
Scheme 1
Aziridines are versatile building blocks for the synthesis
using
(Scheme 1).
a
catalytic amount of indium tribromide
of many biologically interesting molecules such as amino
1
2
3
acids, heterocycles, and alkaloids. They are well known
carbon electrophiles capable of reacting with various nu-
cleophiles and their ability to undergo regioselective ring
opening reactions contributes largely to their synthetic
The treatment of N-tosyl aziridines with aromatic amines
in the presence of 10 mol% InBr in dichloromethane re-
3
sulted in the formation of 1,2-diamines in 78 92% yields.
The reactions proceeded efficiently at ambient tempera-
ture and the products were obtained in excellent yields.
Styrene-N-tosyl aziridine underwent cleavage in a regi-
oselective manner with preferential attack at benzylic po-
sition (entries i,j,k,l). Furthermore, alkyl-N-tosyl aziridine
gave predominantly the ring product 4 with trace amount
of 3 (entry m) resulting from terminal attack as well as in-
ternal attack of amine as observed by others in most azir-
4
value. vic-Diamines are a biologically, medicinally, and
synthetically important class of compounds in the field of
5
anti-HIV drugs such as Zanamivir, Oseltamivir phos-
6
phate and other pharmaceuticals. One of the most
straightforward synthetic procedures for the preparation
of vic-diamines is the ring opening of aziridines with
amines. The ring opening of N-activated aziridines with
7
,8
amines has been studied using Lewis acid catalysis.
However, many of these procedures involve the use of ex-
pensive reagents, extended reaction times, and unsatisfac-
tory yields. Therefore, the development of new reagents
that are more efficient, leading to convenient procedures,
and better yields are well appreciated. In recent years, in-
dium halides have emerged as remarkable Lewis acids in
8
idine ring opening reactions. However, the treatment of
cycloalkyl-N-tosyl aziridines with aromatic amines af-
forded the corresponding ring-opened product as a single
isomer (Scheme 2).
9
promoting various organic transformations. Compared to
conventional Lewis acids, indium halides have advantag-
es of water stability, recoverability, and simplicity in op-
eration. Indeed, such Lewis acids are effective catalysts in
many fundamental reactions including Diels Alder reac-
tions, Michael reactions, Friedel Crafts acylation reac-
tions, Mukaiyama aldol reactions, and Sakurai allylation
reactions. In addition, indium tribromide is found to be
more effective as a catalyst than conventional Lewis acids
in promoting the cyanation of ketones and dithioacetaliza-
tion of carbonyl compounds under mild conditions.11
Scheme 2
In the case of cycloalkyl aziridines, the stereochemistry of
the ring product 3e was found to be trans from the
coupling constants of the ring H-atoms at = 2.95 ppm
1
0
1
(
ddd, J = 4.0, 10.0, and 10.0 Hz, 1 H) for (NCH) in H
NMR spectrum. Likewise, the peak at = 3.10 ppm for
CHN) showed a similar kind of splitting pattern (ddd,
(
In our ongoing programme towards the total synthesis of
anti-HIV molecules such as Zanamivir and Oseltamivir
phosphate, we herein describe a simple and efficient pro-
cedure for the synthesis of 1,2-diamines from aziridines
J = 3.9, 10.0, and 10.0 Hz, 1 H). The method is clean and
highly regioselective, affording 1,2-diamines in excellent
yields. The reaction conditions are mild and no side prod-
ucts or decomposition of the products are observed. All
1
the products were fully characterized by H NMR, IR, and
mass spectroscopic data. The efficacy of other Lewis ac-
ids, such as InCl , CeCl , YCl , and YbCl was studied for
3
3
3
3
Synthesis 2002, No. 8, 04 06 2002. Article Identifier:
this reaction. Among these catalysts, InBr was found to
3
1
437-210X,E;2002,0,08,1061,1064,ftx,en;Z02602SS.pdf.
Georg Thieme Verlag Stuttgart · New York
ISSN 0039-7881
be an excellent catalyst in terms of conversion and reac-
©

1
062
J. S.Yadav et al.
PAPER
tion time. This is because of the mild Lewis acidity of the General Procedure
A mixture of aziridine (5 mmol), amine (5 mmol), and InBr (10
indium(III), which activates the nitrogen atom of the azir-
idine and facilitates the ring opening reaction with
amines. The scope and generality of this process is illus-
trated with various aryl amines and activated aziridines re-
sults are presented in the Table.
3
mol%) in CH Cl (10 mL) was stirred at ambient temperature for a
specified time (Table). After complete conversion, as indicated by
TLC, the reaction mixture was quenched with H O (10 mL) and ex-
tracted with EtOAc (2 15 mL). The combined organic layers were
dried over anhyd Na SO concentrated in vacuo, and purified by
2
2
2
2
4,
column chromatography on silica gel (Merck, 100–200 mesh,
EtOAc hexane, 1:9) to afford pure 1,2-diamine. The aq layer was
concentrated under reduced pressure to recover the catalyst. Spec-
troscopic data for products:
In conclusion, we have demonstrated a convenient and ef-
ficient method for the preparation of 1,2-diamines from
aziridines using a catalytic amount of indium tribromide
under mild reaction conditions. The method has advantag-
es of simplicity in operation, greater selectivity, high 3a
yields of products, and simple experimental/product isola- Solid, mp 98–100 °C.
tion procedures, which makes it a useful and attractive
process for the synthesis of vicinal-diamines.
IR (neat): 3378, 2967, 1621, 1538, 1448, 1332, 1156, 1098, 824,
677 cm .
–
1
1H NMR (400 MHz, CDCl3): = 7.78 (d, 2 , J = 8.2 Hz), 7.23 (d,
2
6
2
1
, J = 8.2 Hz), 7.07 (t, 2 , J = 8.0 Hz), 6.65 (t, 1 H, J = 8.0 Hz),
.43 (d, 2 , J = 8.2 Hz), 5.38 (br d, J = 5.7 Hz, 1 H), 3.30–3.45 (m,
), 2.38 (s, 3 H), 2.08–2.25 (m, 2 ), 1.60–1.85 (m, 2 ), 1.20–
.35 (m, 2 ).
Melting points were recorded on Buchi R-535 apparatus and are un-
corrected. IR spectra were recorded on a Perkin-Elmer FT-IR 240-
c spectrophotometer using KBr optics. H NMR spectra were re-
1
corded on Gemini-200 spectrometer in CDCl using TMS as inter-
3
+
EIMS: m/z = 330 [M ], 175, 132, 120, 91, 56.
nal standard. Mass spectra were recorded on a Finning MAT 1020
mass spectrometer operating at 70 eV. CHN analyses were recorded
on a Vario EL analyzer.
Anal. Calcd for C H N O S (330.44): C, 65.43; H, 6.71; N, 8.48;
S, 9.70. Found: C, 65.45; H, 6.73; N, 8.50; S, 9.72.
1
8
22
2
2
Table Indium Tribromide Catalyzed Aminolysis of Aziridines with Aryl Amines
Entry
Aziridine
Amine
10% InBr3
Time (h)
10% YbCl3
Time (h)
Ratio 3:4
Yield (%)a
92
Yield (%)a
81
-
a
b
c
d
e
C H NH
2
6.0
5.5
8.0
7.0
5.5
7.5
6.5
8.0
9.0
7.0
-
-
-
-
-
6
5
4-MeC H NH
2
90
80
85
90
84
72
75
82
6
4
4-MeOC H NH
2
6
4
2-Naphthylamine
C H NH
6
5
2
f
4-MeC H NH
2
5.0
8.0
7.5
4.0
88
83
78
90
6.5
7.0
9.0
6.0
80
71
69
83
-
6
4
g
h
i
4-MeOC H NH
2
-
6
4
2,5-(MeO) C H NH
2
-
2
6
3
C H NH
2
78:22b
6
5
j
4-MeC H NH
2
3.5
6.0
6.5
7.0
88
80
83
85
5.5
8.0
7.0
9.0
81
70
75
71
85:15b
87:13b
95:5b
6
4
k
l
4-MeOC H NH
6 4 2
4-BrC H NH
6
4
2
m
C H NH
5:95b
6
5
2
a
Isolated, unoptimized yield.
Ratio of products from internal attack vs terminal attack.
b
Synthesis 2002, No. 8, 1061–1064 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Aminolysis of Aziridines
1063
3
b
1
2
), 2.45 (s, 3 H), 2.25 (s, 3 H), 2.08–2.20 (m, 2 ), 1.65–1.70 (m,
), 1.29–1.38 (m, 3 H), 1.02–1.08 (m, 1 ).
Solid, mp 133–135 °C.
+
EIMS: m/z = 358 [M ], 203, 96, 91, 65.
IR (neat): 3357, 2948, 1632, 1527, 1430, 1357, 1147, 1078, 830,
7
–1
68 cm .
Anal. Calcd for C H N O S (358.49): C, 67.01; H, 7.31; N, 7.81;
2
0
26
2
2
1H NMR (400 MHz, CDCl3): = 7.78 (d, 2 , J = 8.2 Hz), 7.20 (d,
S, 8.94. Found: C, 67.03; H, 7.35; N, 7.83; S, 8.97.
2
5
, J = 8.2 Hz), 6.85 (d, 2 , J = 8.0 Hz), 6.38 (d, 2 , J = 8.2 Hz),
.40 (m, 1 , NH), 3.20 (br s, 1 , NH), 3.25–3.40 (m, 2 ), 2.45
3
g
Solid, mp 130–132 °C.
(s, 3 H), 2.25 (s, 3 H), 2.08–2.25 (m, 2 ), 1.60–1.85 (m, 2 ),
1
.20–1.35 (m, 2 ).
IR (neat): 3364, 2928, 1620, 1516, 1447, 1334, 1246, 1093, 820,
730 cm .
1H NMR (400 MHz, CDCl3): = 7.78 (d, 2 , J = 8.1 Hz), 7.30 (d,
–
1
+
EIMS: m/z = 344 [M ], 210, 189, 172, 155, 141, 110, 91, 82, 55.
Anal. Calcd for C H N O S (344.47): C, 66.25; H, 7.02; N, 8.13;
S, 9.31. Found: C, 66.27; H, 7.05; N, 8.15; S, 9.32.
19
24
2
2
2
5
, J = 8.1 Hz), 6.68 (d, 2 , J = 8.0 Hz), 6.43 (d, 2 , J = 8.0 Hz),
.0 (br d, J = 5.1 Hz, NH), 3.78 (s, 3 H), 2.90 (br s, 1 , NH), 3.05
(
1
(
ddd, J = 3.7, 10.2, 10.2 Hz, NCH, 1 ), 2.90 (ddd, J = 4.0, 10.2,
0.2 Hz, NCH, 1 ), 2.45 (s, 3 H), 2.05–2.20 (m, 2 ), 1.65–1.70
m, 2 ), 1.35–1.25 (m, 2 ), 0.99–1.07 (m, 1 ).
3
c
Solid, mp 58–60 °C.
–
1
IR (neat): 3368, 2943, 1626, 1512, 1324, 1154, 1091, 816, 667 cm .
1H NMR (400 MHz, CDCl3): = 7.78 (d, 2 , J = 8.2 Hz), 7.50 (d,
2
5
+
EIMS: m/z = 374 [M ], 219, 202, 149, 134, 96, 91, 43.
Anal. Calcd for C H N O S (374.49): C, 64.14; H, 7.0; N, 7.48; S,
8
1
9
26
2
3
, J = 8.3 Hz), 7.25 (d, 2 , J = 8.2 Hz), 6.60 (d, 2 , J = 8.3 Hz),
.56. Found: C, 64.16; H, 7.03; N, 7.49; S, 8.58.
.40 (br s, 1 , NH), 3.98–4.09 (m, 1 ), 3.80 (s, 3 H), 3.65–3.78
(
1
m, 1 ), 2.40 (s, 3 H), 2.05 2.20 (m, 2 ), 1.63–1.80 (m, 2 ),
.20–1.37 (m, 2 ).
3
h
Solid, mp 108–110 °C.
+
EIMS: m/z = 360 [M ], 205, 173, 141, 123, 108, 80, 53.
IR (neat): 3378, 2933, 1617, 1522, 1428, 1328, 1158, 1078, 830,
Anal. Calcd for C H N O S (360.47): C, 63.31; H, 6.71; N, 7.77;
–1
19
24
2
3
668 cm .
S, 8.89. Found: C, 63.34; H, 6.73; N, 7.79; S, 8.90.
1H NMR (400 MHz, CDCl3): = 7.75 (d, J = 8.2 Hz, 2 ), 7.25 (d,
J = 8.2 Hz, 2 ), 6.75 (d, J = 8.1 Hz, 2 ), 6.45 (d, J = 8.1 Hz, 2 ),
3
d
5
(
.20 (br d, J = 5.3 Hz, 1 ), 3.85 (br s, 1 , NH), 3.75 (s, 3 H), 3.70
s, 3 H), 3.05 (ddd, J = 3.9, 10.5, 10.5, Hz, NCH, 1 ), 2.95 (ddd,
J = 4.0, 10.5, 10.5 Hz, NCH, 1 ), 2.43 (s, 3 H), 2.05–2.20 (m, 2
Solid, mp 100–102 °C.
IR (neat): 3378, 2933, 1617, 1522, 1428, 1328, 1158, 1078, 830,
–
1
6
68 cm .
)
, 1.59–1.65 (m, 2 ), 1.20–1.35 (m, 3 H), 1.03–1.08 (m, 1 ).
1H NMR (400 MHz, CDCl3): = 7.78 (d, J = 8.2 Hz, 2 ), 7.55–
.68 (m, 3 H), 7.38 (t, J = 8.0 Hz, 1 ), 7.20–7.25 (m, 1 ), 7.18 (d,
, J = 8.2 Hz), 6.80 (d, J = 8.0 Hz, 2 ), 5.60 (br s, NH, 1 ), 3.80
br s, NH, 1 ), 3.60 (ddd, J = 3.9, 9.8, 9.8 Hz, NCH, 1 ), 3.55
ddd, J = 4.0, 9.8, 9.8 Hz, NCH, 1 ), 2.38 (s, 3 H), 2.05–2.20 (m,
+
EIMS: m/z = 404 [M ], 249, 232, 153, 138, 96, 91, 41.
7
2
(
(
1
Anal. Calcd for C H N O S (404.52): C, 62.35; H, 6.98; N, 6.93;
2
1
28
2
4
S, 7.93. Found: C, 62.38; H, 6.99; N, 6.96; S, 7.95.
3
i
), 1.85–1.90 (m, 2 ), 1.70–1.80 (m, 1 ), 1.38–1.48 (m, 2 ).
Solid, mp 150–152 °C.
+
EIMS: m/z = 380 [M ], 225, 182, 170, 127, 115, 91, 56.
IR (KBr): 3368, 2942, 1619, 1518, 1448, 1328, 1257, 1158, 1085,
Anal. Calcd for C H N O S (380.50): C, 69.45; H, 6.36; N, 7.36;
–1
22
24
2
2
808 cm .
S, 8.43. Found: C, 69.47; H, 6.38; N, 7.39; S, 8.45.
1
H NMR (200 MHz, CDCl ): = 7.78 (d, 2 , J = 8.0 Hz), 7.58–
3
7
1
.63 (m, 1 ), 7.20–7.38 (m, 6 H), 7.05 (t, 2 , J = 7.8 Hz), 6.60 (t,
, J = 7.8 Hz), 6.40 (d, 2 , J = 8.0 Hz), 5.25 (br d, 1 , J = 6.5
3
e
Solid, mp 152–154 °C.
Hz), 4.30 (dd, 1 , J = 4.0, 9.8 Hz), 3.18 (ddd, 1 , J = 4.0, 9.8,
1
–
1
IR (neat): 3400, 2958, 1620, 1528, 1423, 1324, 1092, 824, 732 cm .
1H NMR (400 MHz, CDCl3): = 7.70 (d, 2 , J = 8.3 Hz), 7.30 (d,
2
6
0.0 Hz), 3.0 (ddd, 1 , J = 3.7, 9.8, 10.0 Hz), 2.40 (s, 3 H).
+
EIMS: m/z = 366 [M ], 180, 155, 104, 91, 77, 65.
, J = 8.3 Hz), 7.08 (t, 2 , J = 8.0 Hz), 6.65 (t, 1 , J = 8.0 Hz),
.40 (d, 2 , J = 8.3 Hz), 4.84 (br d, J = 5.5 Hz, 1 ), 3.40 (br s, 1
)
Anal. Calcd for C H N O S (366.47): C, 68.83; H, 6.05; N, 7.64;
S, 8.74. Found: C, 68.85; H, 6.07; N, 7.66; S, 8.77.
2
1
22
2
2
, 3.10 (ddd, J = 3.9, 10.0, 10.0 Hz, NCH, 1 ), 2.95 (ddd,
J = 4.0, 10.0, 10.0 Hz, NCH, 1 ), 2.45 (s, 3 H), 2.03 2.20 (m, 2
3
j
), 1.65–1.70 (m, 2 ), 1.23–1.38 (m, 3 H), 0.99–1.05 (m, 1 ).
Solid, mp 88–90 °C.
+
EIMS: m/z = 344 [M ], 189, 172, 141, 96, 91, 65.
IR (KBr): 3378, 2938, 1629, 1530, 1428, 1313, 1262, 1188, 1095,
Anal. Calcd for C H N O S (344.47): C, 66.25; H, 7.02; N, 8.13;
–1
19
24
2
2
818 cm .
S, 9.31. Found: C, 66.27; H, 7.03; N, 8.15; S, 9.34.
1H NMR (200 MHz, CDCl3): = 7.75 (d, 2 , J = 8.0 Hz), 7.20–
7
4
.38 (m, 7 H), 6.85 (d, 2 , J = 8.2 Hz), 6.38 (d, 2 , J = 8.2 Hz),
.95 (br s, 1 , NH), 4.38 (dd, 1 , J = 4.0, 9.9 Hz), 4.35 (br s, 1
3
f
,
Solid, mp 157–159 °C.
NH), 3.25 (ddd, 1 , J = 4.0, 9.9, 10.3 Hz), 3.10 (ddd, 1 , J = 3.8,
9
–
1
IR (neat): 3348, 2967, 1525, 1458, 1332, 1267, 1159, 830, 732 cm .
.9, 10.3 Hz), 2.40 (s, 3 H), 2.18 (s, 3 H).
1
H NMR (400 MHz, CDCl ): = 7.80 (d, 2 , J = 8.2 Hz), 7.38 (d,
+
3
EIMS: m/z = 380 [M ], 196, 155, 141, 91, 43.
2
5
1
, J = 8.2 Hz), 6.98 (d, 2 , J = 8.0 Hz), 6.40 (d, 2 , J = 8.0 Hz),
.02 (br d, J = 5.7 Hz, NH), 3.20 (br s, 1 , NH), 3.03 (ddd, J = 3.8,
0.3, 10.3 Hz, NCH, 1 ), 2.97 (ddd, J = 4.0, 10.3, 10.3 Hz, NCH,
Anal. Calcd for C H N O S (380.50): C, 69.45; H, 6.36; N, 7.36;
S, 8.43. Found: C, 69.47; H, 6.37; N, 7.38; S, 8.45.
2
2
24
2
2
Synthesis 2002, No. 8, 1061–1064 ISSN 0039-7881 © Thieme Stuttgart · New York

1
064
J. S.Yadav et al.
PAPER
3
k
Acknowledgements
Solid, mp 63–65 °C.
BVS, KVR thank CSIR New Delhi, for the award of fellowships.
IR (KBr): 3380, 2924, 1600, 1510, 1455, 1327, 1260, 1145, 1091,
8
–1
09 cm .
1H NMR (200 MHz, CDCl3): = 7.78 (d, 2 , J = 8.0 Hz), 7.20–
References
7
4
3
9
.38 (m, 7 H), 6.63 (d, 2 , J = 7.8 Hz), 6.40 (d, 2 , J = 8.0 Hz),
.80 (br t, 1 , J = 6.0 Hz), 4.37 (dd, 1 , J = 4.0, 9.8 Hz), 3.65 (s,
H), 3.25 (ddd, 1 , J = 4.0, 9.8, 10.0 Hz), 3.15 (ddd, 1 , J = 3.7,
.8, 10.0 Hz), 2.43 (s, 3 H).
(
1) (a) Tanner, D. Angew. Chem., Int. Ed. Engl. 1994, 33, 599.
b) McCoull, W.; Davis, F. A. Synthesis 2000, 1347.
(
(
2) (a) Dureault, A.; Tranchepain, I.; Depezay, J. C. J. Org.
Chem. 1989, 54, 5324. (b) Tanner, D.; He, H. M.
Tetrahedron 1992, 48, 6079.
+
EIMS: m/z = 396 [M ], 359, 212, 156, 141, 106, 91, 43.
(
3) Hudlicky, T.; Luna, H.; Price, J. D.; Rulin, F. J. Org. Chem.
Anal. Calcd for C H N O S (396.50): C, 66.64; H, 6.10; N, 7.07;
S, 8.09. Found: C, 66.67; H, 6.13; N, 7.08; S, 8.10.
21
28
2
4
1990, 55, 4683.
(
4) (a) Katritzky, A. R.; Rees, C. W. In Comprehensive
Heterocylic Chemistry, Vol. 7; Pergamon Press: Oxford,
3
l
1984, 47. (b) Kump, J. E. G. In Comprehensive Organic
Solid, mp 135–137 °C.
Synthesis, Vol 7; Trost, B. M.; Fleming, I., Eds.; Pergamon
Press: Oxford, 1991, 469.
IR (KBr): 3382, 2948, 1630, 1570, 1430, 1378, 1168, 1069, 967
–
1
cm .
(
5) (a) Graul, A.; Castarer, J. Drugs Future 1999, 24, 1175.
(b) Smith, P. W.; Sollis, S. L.; Howes, P. D.; Cherry, P. C.;
Starkey, I. D.; Cobley, K. N.; Weston, H.; Scicinski, J.;
Merritt, A.; Whittington, A.; Wyatt, P.; Taylor, N.; Green,
D.; Bethell, R. C.; Madar, S.; Fenton, R. J.; Morley, P. J.;
Patemann, T.; Beresford, A. J. Med. Chem. 1998, 41, 787.
1H NMR (200 MHz, CDCl3): = 7.75 (d, 2 , J = 8.0 Hz), 7.20–
7
4
.35 (m, 7 H), 7.10 (d, 2 , J = 8.0 Hz), 6.30 (d, 2 , J = 8.0 Hz),
.80 (br t, 1 , J = 6.0 Hz), 4.65 (br s, 1 , NH), 4.35 (dd, 1
,
J = 4.0, 10.2 Hz), 3.27 (ddd, 1 , J = 4.0, 9.8, 10.2 Hz), 3.15 (ddd,
1
, J = 3.8, 9.8, 10.2 Hz), 2.40 (s, 3 H).
(
c) Smith, P. W.; Robinson, J. E.; Evans, D. N.; Sollis, S. L.;
+
MS FAB: m/z = 444 [M ], 262, 184, 155, 141, 91, 57.
Howes, P. D.; Trivedi, N.; Bethell, R. C. Bioorg. Med.
Chem. Lett. 1999, 9, 601.
Anal. Calcd for C H BrN O S (445.37): C, 56.63; H, 4.75; Br,
21
21
2
2
1
6
7.94; N, 6.29; S, 7.20. Found: C, 56.65; H, 4.78; Br, 17.96; N,
.31; S, 7.23.
(6) Reetz, M. T.; Jaeger, R.; Drewlies, R.; Hubel, M. Angew.
Chem., Int. Ed. Engl. 1991, 30, 103; and references cited
therein.
3
m
(7) (a) Meguro, M.; Asao, N.; Yamamoto, Y. Tetrahedron Lett.
1994, 35, 7395. (b) Sekar, G.; Singh, V. K. J. Org. Chem.
Solid, mp 68–70 °C.
1
999, 64, 2537.
IR (KBr): 3268, 2930, 1602, 1508, 1433, 1318, 1158, 1089, 966,
–1
(8) Meguro, M.; Yamamoto, Y. Heterocycles 1996, 43, 2473.
8
15, 751 cm .
(
9) (a) Yadav, J. S.; Reddy, B. V. S.; Kumar, G. M. Synlett 2001,
1417. (b) Yadav, J. S.; Sunny, A.; Reddy, B. V. S.; Sabitha,
G. Synthesis 2001, 2165. (c) Yadav, J. S.; Sunny, A.; Reddy,
B. V. S.; Sabitha, G. Tetrahedron Lett. 2001, 42, 8063.
1H NMR (200 MHz, CDCl3): = 7.78 (d, 2 , J = 8.0 Hz), 7.20 (d,
2
6
9
, J = 8.3 Hz), 7.05 (t, 2 , J = 7.8 Hz), 6.70 (t, 1 , J = 7.8 Hz),
.40 (d, 2 , J = 8.0 Hz), 5.15 (m, 1 , NH), 4.20 (dd, 1 , J = 4.0,
.8 Hz), 3.15 (ddd, 1 , J = 4.0, 9.8, 10.0 Hz), 3.0 (ddd, 1
,
(d) Yadav, J. S.; Reddy, B. V. S.; Kumar, G. M. Synlett 2001,
J = 3.5, 9.8, 10.0 Hz), 2.43 (s, 3 H), 1.38–1.50 (m, 2 ), 1.08–1.20
1781.
(
m, 4 H), 0.80 (t, 3 H, J = 6.8 Hz).
(
(
10) (a) Li, C. J.; Chan, T.-H. Tetrahedron 1999, 55, 11149.
(b) Babu, G.; Perumal, P. T. Aldrichima Acta. 2000, 33, 16.
+
EIMS: m/z = 346 [M ], 162, 106, 91, 65.
(c) Ghosh, R. Indian J. Chem. 2001, 40B, 550.
Anal. Calcd for C H N O S (346.48): C, 65.86; H, 7.56; N, 8.09;
19
26
2
2
11) (a) Bandini, M.; Giorgio Cozzi, P.; Melchiorre, P.; Umani-
Ronchi, A. Tetrahedron Lett. 2001, 42, 3041. (b) Ceschi,
M. A.; Felix, L. A.; Peppe, C. Tetrahedron Lett. 2000, 41,
S, 9.25. Found: C, 65.88; H, 7.59; N, 8.11; S, 9.27.
9695.
Synthesis 2002, No. 8, 1061–1064 ISSN 0039-7881 © Thieme Stuttgart · New York