Reactions of Morita-Baylis-Hillman acetates with Huisgen zwitterions: A novel strategy for the synthesis of β-amino acid derivatives

Article abstract of DOI:10.1055/s-0028-1088063

The reaction of Huisgen Zwitterion with Morita-Baylis-Hillman acetates afforded β-amino acid derivatives. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-0028-1088063

PAPER
1829
Reactions of Morita–Baylis–Hillman Acetates with Huisgen Zwitterions:
A Novel Strategy for the Synthesis of b-Amino Acid Derivatives
N
ovel Strategy for
n
the Synthesi
u
s
of
b
-Amino
A
cid
J
D
erivativ
o
es se,a Rony Rajan Paul,a Resmi Mohan,a Smitha C. Mathew,a A. T. Biju,a Eringathodi Suresh,b Vijay Nair*a
a
Organic Chemistry Section, National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum 695019, India
Fax +91(471)2491712; E-mail: vijaynair_2001@yahoo.com
b
Analytical Science Discipline, Central Salt and Marine Chemicals Research Institute, Bhavanagar 364002, India
Received 16 January 2009; revised 23 January 2009
the compound 3a showed singlet resonance signals at d =
2.35 and 3.81 due to CH3CO group and CH3OCO groups.
The NCH2 group was discernable at d = 4.14–4.73 as a
multiplet. In the 13C NMR spectrum the three ester carbo-
nyl groups were present at d = 169.4, 167.4 and 154.7 and
that of the keto carbonyl group appeared at d = 152.7, sup-
porting the IR absorption observed in the region 1750–
1700 and 1631 cm–1. All other signals were also in good
agreement with the proposed structure. The structure and
stereochemistry of the compound was unambiguously es-
tablished by single crystal X-ray analysis (Figure 1) of a
representative compound, 3g.
Abstract: The reaction of Huisgen Zwitterion with Morita–Baylis–
Hillman acetates afforded b-amino acid derivatives.
Key words: Huisgen zwitterion, Morita–Baylis–Hillman acetate,
b-amino acid
Although Huisgen zwitterion1 was known for nearly four
decades, its synthetic potential remained largely unex-
ploited except in some notable reactions like Mitsunobu
Reaction.2 In view of our longstanding interest in zwitter-
ion chemistry,3 recently we have explored the reactivity of
Huisgen zwitterion towards various substrates like alde-
hydes, ketones, chalcones, diaryl 1,2-diones, quinones,
isatins, and allenes.4–6 In this context it was of interest to
examine the reactivity of Huisgen zwitterion towards
Morita–Baylis–Hillman (MBH) adducts,7,8 which are
unique substrates of great synthetic potential incorporat-
ing three manipulatable groups, namely, a hydroxy group,
a double bond, and an electron-withdrawing group. In this
paper, we describe the results of our investigations on the
reaction of Huisgen zwitterion with MBH acetates.
The present studies were initiated by treating methyl 2-
[(4-chlorophenyl)acetyloxymethyl]acrylate (1a) with di-
isopropyl azodicarboxylate and triphenylphosphine in
THF at room temperature for 2 hours. The reaction afford-
ed two products, namely, diisopropyl N-acetyl-N¢-[3-(4-
chlorophenyl)-2-(methoxycarbonyl)allyl]hydrazine-1,2-
dicarboxylate (3a) and diisopropyl N-[3-(4-chlorophe-
nyl)-2-(methoxycarbonyl) allyl]hydrazine-1,2-dicarboxy-
late (4a) in 46% and 51% yield, respectively (Scheme 1).
Figure 1 Single crystal X-ray structure of di-tert-butyl N-acetyl-N¢-
[3-(3,4-dichlorophenyl)-2-(methoxycarbonyl)allyl]hydrazine-1,2-di-
carboxylate (3g)
The structure elucidation of 3a and 4a was accomplished
by usual spectroscopic analysis. The 1H NMR spectrum of
i-PrO2C
N
N
OMe
O
OMe
OAc
O
CO2i-Pr
2a
PPh3
O
CO2i-Pr
OMe
+
CO2i-Pr
Cl
N
N
THF, N2
r.t., 2 h
Cl
N
N
Cl
COMe
i-PrO2C
3a
i-PrO2C
H
1a
4a
Scheme 1 Reaction of Huisgen zwitterion with MBH acetate
SYNTHESIS 2009, No. 11, pp 1829–1833
x
x.
x
x
.
2
0
0
9
Advanced online publication: 27.04.2009
DOI: 10.1055/s-0028-1088063; Art ID: Z01009SS
© Georg Thieme Verlag Stuttgart · New York

1830
A. Jose et al.
PAPER
O
Table 1 Hydrazine-1,2-dicarboxylates 3 and 4 Prepared
O
R2O2C
OMe
N
N
OMe
CO2i-Pr
X
X
R1
R1
Cl
N
N
CO2R2
OAc
2
CO2i-Pr
CO2R2
COMe
Cl
N
CO2R2
Ph3P
X
+
– Ph3P=O
N
N
N
R1
NH
i-PrO2C
THF, N2
r.t., 2 h
PPh3
OH
NH
i-PrO2C
R2O2C
R2O2C
4a
7
1
3
4
H2O
3, 4
R1
R2
X
Yield (%)
3
4
O
OAc
O
a
b
c
d
e
f
4-ClC6H4
4-CF3C6H4
3-ClC6H4
Ph
i-Pr
Et
CO2Me
CO2Me
CO2Me
CO2Me
CN
46
57
38
35
57
37
58
35
40
54
51
41
49
56
37
46
30
49
36
40
OMe
OMe
–
–OAc
Cl
CO2i-Pr
N
N
Cl
1a
Et
i-PrO2C
CO2i-Pr
i-PrO2C
+
PPh3
i-PrO2C
i-Pr
i-Pr
t-Bu
t-Bu
Et
N–
N
5
Ph
Ph3P+
CO2i-Pr
i-PrO2C
N
N
–OAc
4-FC6H4
3,4-Cl2C6H3
Ph
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
Huisgen zwitterion
••
g
h
i
PPh3
O
OMe
4-MeC6H4
4-BrC6H4
i-Pr
i-Pr
O
CO2i-Pr
Cl
N
N
j
OMe
CO2i-Pr
PPh3
O
Cl
N
N
– Ph3P=O
The IR spectrum of the compound 4a showed strong ab-
sorptions at 3308 and 1703–1722 cm–1 due to NH group
and the ester carbonyl groups, respectively. The 1H NMR
showed singlets at d = 4.5 and 6.71 due to NCH2 and NH
groups. In the 13C NMR spectrum signals due to the ester
carbonyl groups were discernable at d = 155.5, 156.3, and
167.7. Other signals were also in good agreement with the
proposed structure.
Me
i-PrO2C
COMe
3a
6
O
Scheme 2 Mechanistic rationale for the formation of hydrazine-1,2-
dicarboxylates 3a and 4a
In conclusion, herein we have reported a facile C–N bond-
forming reaction, which incidentally constitutes the first
example of the participation of Huisgen zwitterions in an
SN2¢ reaction.
The mechanism of the reaction may be rationalized by in-
voking an SN2¢ process, involving the Huisgen zwitterion
and the Morita–Baylis–Hillman acetate (Scheme 2). Evi-
dently, the first step of the reaction is the formation of
Huisgen zwitterion by the addition of triphenylphosphine
to diisopropyl azodicarboxylate. The SN2¢ displacement
of the acetate from 1a induced by Huisgen zwitterion
would lead to the formation of the cationic intermediate 5.
The attack of the acetate on 5 followed by rearrangement
and the elimination of Ph3PO, would result in the forma-
tion of diisopropyl N-acetyl-N¢-[3-(4-chlorophenyl)-2-
(methoxycarbonyl)allyl]hydrazine-1,2-dicarboxylate (3a).
Similarly by the addition of hydroxy anion to 5, an inter-
mediate 7 is formed, and the latter on elimination of tri-
phenylphosphine oxide would deliver diisopropyl N-[3-
(4-chlorophenyl)-2-(methoxycarbonyl)allyl]hydrazine-
1,2-dicarboxylate (4a).
Melting points were recorded on a Büchi melting point apparatus
and are uncorrected. NMR spectra were recorded at 300 MHz (1H)
and 75 MHz (13C) respectively on a Bruker Avance DPX-300 MHz
NMR spectrometer. Chemical shifts are reported (d) relative to
TMS (1H) and CDCl3 (13C) as the internal standards. Coupling con-
stants (J) are reported in Hertz (Hz). High-resolution mass spectra
were recorded under EI/HRMS (at 5000 resolution) or FAB+/
HRMS using Jeol JMS 600H mass spectrometer. IR spectra were
recorded on Nicolet Impact 400D FT-IR spectrophotometer. Com-
mercial grade solvents were distilled prior to use.
Reactions of Morita–Baylis–Hillman Acetates with Huisgen
Zwitterions; General Procedure
The Morita–Baylis–Hillman acetate 1 (1 equiv) dissolved in THF (5
mL) was treated with the respective azodicarboxylate 2 (1.2 equiv)
and Ph3P (1.2 equiv) at r.t. for 2 h under N2. The solvent was re-
moved under reduced pressure and the crude reaction mixture was
purified by column chromatography using silica gel (60–120 mesh)
and hexane–EtOAc.
As disclosed inTable 1, the reaction was found to be gen-
eral with various Morita–Baylis–Hillman acetates and
Huisgen zwitterions.
Synthesis 2009, No. 11, 1829–1833 © Thieme Stuttgart · New York

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Novel Strategy for the Synthesis of b-Amino Acid Derivatives
1831
Diisopropyl N-Acetyl-N¢-[3-(4-chlorophenyl)-2(methoxycarbo-
nyl)allyl]hydrazine-1,2-dicarboxylate (3a)
Yield: 46%.
13C NMR (75.47 MHz, CDCl3): d = 14.0, 14.5, 14.6, 25.2, 43.9,
125.9, 126.5, 130.4, 131.5, 131.9, 143.8, 144.0, 153.2, 154.7, 162.2,
167.8, 169.5.
IR (KBr): 2983, 1750–1700, 1631, 1582 cm–1.
HRMS (EI): m/z calcd for C19H23ClN2O7: 426.1217; found:
426.1219.
1H NMR (300 MHz, CDCl3): d = 1.18–1.34 (m, 12 H), 2.35 (s, 3 H),
3.81 (s, 3 H), 4.24–4.73 (m, 2 H), 4.88–5.00 (m, 2 H), 7.26–7.38 (m,
4 H), 7.83 (s, 1 H).
13C NMR (75.47 MHz, CDCl3): d = 21.3, 21.6, 21.7, 22.1, 25.1,
42.8, 51.5, 70.2, 71.7, 126.7, 127.1, 128.8, 130.9, 132.8, 135.5,
140.4, 143.5, 152.7, 154.2, 167.4, 169.4.
Diethyl N¢-[3-(3-Chlorophenyl)-2-(methoxycarbonyl)allyl]hy-
drazine-1,2-dicarboxylate (4c)
Yield: 49%.
IR (KBr): 3424, 2983, 1759–1699 (br), 1487 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.16–1.29 (m, 6 H), 3.74 (s, 3 H),
4.03–4.15 (m, 4 H), 4.52 (s, 2 H), 6.72 (s, 1 H), 7.00–7.33 (m, 4 H),
7.75 (s, 1 H).
HRMS (EI): m/z calcd for C21H27ClN2O7: 454.1507; found:
454.0291.
Diisopropyl N¢-[3-(4-Chlorophenyl)-2-(methoxycarbonyl)al-
lyl]hydrazine-1,2-dicarboxylate (4a)
Yield: 51%.
IR (KBr): 3309, 2983, 1722–1703 cm–1.
13C NMR (75.47 MHz, CDCl3): d = 14.2, 14.5, 46.7, 52.2, 61.9,
62.5, 115.6, 126.9, 130.5, 131.5, 142.8, 155.9, 162.0, 164.0.
HRMS (EI): m/z calcd for C17H21ClN2O6: 384.1107; found:
384.1111.
1H NMR (300 MHz, CDCl3): d = 1.14–1.25 (m, 12 H), 3.74 (s, 3 H),
4.5 (s, 2 H), 4.77– 4.92 (m, 2 H), 6.71 (s, 1 H), 7.13–7.28 (m, 4 H),
7.72 (s, 1 H).
13C NMR (75.47 MHz, CDCl3): d = 21.6, 21.9 45.5, 51.7, 69.4,
70.1, 128.3, 128.7, 129.7, 130.7, 133.5, 135.1, 142.3, 155.5, 156.3,
167.7.
Diisopropyl N-Acetyl-N¢-[3-phenyl-2-(methoxycarbonyl)al-
lyl]hydrazine-1,2-dicarboxylate (3d)
Yield: 35%.
IR (KBr): 1712, 1249 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.16–1.28 (m, 12 H), 2.30 (s, 3 H),
3.81 (s, 3 H), 4.53–4.80 (m, 4 H), 4.87–4.99 (m, 2 H), 7.38 (m, 5 H),
7.90 (s, 1 H).
13C NMR (75.47 MHz, CDCl3): d = 21.1, 21.5, 21.9, 25.0, 52.0,
70.0, 70.4, 71.5, 128.5, 129.1, 129.4, 129.5, 145.0, 152.7, 154.1,
167.7, 169.3.
HRMS (EI): m/z calcd for C19H25ClN2O6: 412.1401; found:
412.1396.
Diethyl N-Acetyl-N¢-[3-(4-trifluoromethylphenyl)-2-(methoxy-
carbonyl)allyl]hydrazine-1,2-dicarboxylate (3b)
Yield: 57%.
IR (KBr): 1715 (br), 1242, 1103 cm–1.
HRMS (EI): m/z calcd for C21H28N2O7: 420.1910; found: 420.1907.
Diisopropyl N¢-[3-Phenyl-2-(methoxycarbonyl)allyl]hydrazine-
1,2-dicarboxylate (4d)
Yield: 56%.
IR (KBr): 3211, 2991, 1753–1698 (br) cm–1.
1H NMR (300 MHz, CDCl3): d = 1.20–1.32 (m, 12 H), 4.11 (s, 3 H),
4.62 (s, 2 H), 4.92–4.98 (m, 2 H), 6.62 (s, 1 H), 7.37 (s, 5 H), 7.86
(s, 1 H).
1H NMR (300 MHz, CDCl3): d = 1.17–1.25 (m, 6 H), 2.35 (s, 3 H),
3.82 (s, 3 H), 4.10–4.16 (m, 4 H), 4.53–4.74 (m, 2 H), 7.38 (m, 2 H),
7.67 (d, J = 8.0 Hz, 2 H), 7.89 (s, 1 H).
13C NMR (75.47 MHz, CDCl3): d = 13.9, 14.1, 14.4, 25.1, 43.1,
52.3, 62.7, 63.6, 124.9, 125.4, 128.7, 128.9, 129.7, 131.2, 137.9,
142.9, 153.1, 154.5, 167.3, 169.3.
HRMS (EI): m/z calcd for C20H23F3N2O7: 460.1456; found:
454.1457.
13C NMR (75.47 MHz, CDCl3): d = 21.7, 21.8, 21.9, 43.3, 52.0,
70.0, 70.2, 70.3, 128.9, 129.3, 134.4, 155.6, 156.4, 166.5.
Diethyl N¢-[3-(4-Trifluoromethylphenyl)-2-(methoxycarbon-
yl)allyl]hydrazine-1,2-dicarboxylate (4b)
Yield: 41%.
LRMS-FAB: m/z calcd for C19H26ClN2O6 (M + H)+: 379.18; found:
379.20.
IR (KBr): 3421, 2999, 1755–1697 (br), 1263 cm–1.
Diisopropyl N-Acetyl-N¢-[(3-phenyl-2-cyano)allyl]hydrazine-
1,2-dicarboxylate (3e)
Yield: 57%.
IR (KBr): 3037, 2218, 1762–1703 (br), 1361 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.22–1.30 (m, 6 H), 3.84 (s, 3 H),
4.11–4.23 (m, 4 H), 4.57 (s, 2 H), 6.78 (s, 1 H), 7.54 (m, 2 H), 7.65
(d, J = 8.1 Hz, 2 H), 7.87 (s, 1 H).
13C NMR (75.47 MHz, CDCl3): d = 13.9, 14.1, 14.4, 25.1, 43.1,
52.3, 62.7, 63.6, 124.9, 125.4, 128.7, 128.9, 129.7, 131.2, 137.9,
142.9, 153.1, 154.5, 167.3, 169.5.
1H NMR (300 MHz, CDCl3): d = 1.19–1.33 (m, 12 H), 2.56 (s, 3 H),
4.95–5.04 (m, 2 H), 7.40–7.42 (m, 5 H), 7.77 (s, 1 H).
13C NMR (75.47 MHz, CDCl3): d = 21.3, 21.6, 25.1, 45.7, 53.1,
70.5, 72.1, 106.2, 109.9, 117.9, 119.4, 128.7, 129.8, 130.6, 132.6,
146.1, 147.8, 152.4, 153.3, 154.0, 169.7.
HRMS (EI): m/z calcd for C18H12F3N2O6: 418.1461; found:
418.1463.
LRMS (+FAB): m/z calcd for C20H23ClN3O5 (M + H)+: 388.18;
found: 388.21.
Diethyl N-Acetyl-N¢-[3-(3-chlorophenyl)-2-(methoxycarbon-
yl)allyl]hydrazine-1,2-dicarboxylate (3c)
Yield: 38%.
IR (KBr): 1713, 1240 cm–1.
Diisopropyl N-[(3-Phenyl-2-cyano)allyl]hydrazine-1,2-dicar-
boxylate (4e)
Yield: 37%.
1H NMR (300 MHz, CDCl3): d = 1.17–1.27 (m, 6 H), 2.36 (s, 3 H),
3.80 (s, 3 H), 4.11–4.24 (m, 4 H), 4.34–4.74 (m, 2 H), 7.06–7.46 (m,
4 H), 7.55 (s, 1 H).
IR (KBr): 3413, 2988, 2216, 1752–1715 (br), 1481, 1381 cm–1.
Synthesis 2009, No. 11, 1829–1833 © Thieme Stuttgart · New York

1832
A. Jose et al.
PAPER
1H NMR (300 MHz, CDCl3): d = 1.25–1.33 (m, 12 H), 4.43–4.53
(m, 2 H), 4.89–5.05 (m, 2 H), 6.89 (s, 1 H), 7.41–7.75 (m, 5 H), 7.76
(s, 1 H).
Diisopropyl N-Acetyl-N¢-[3-(4-methylphenyl)-2(methoxycarbo-
nyl)allyl]hydrazine-1,2-dicarboxylate (3i)
Yield: 40%.
13C NMR (75.47 MHz, CDCl3): d = 21.6, 21.9, 52.5, 69.7, 69.9,
IR (KBr): 3314, 2982, 1739–1723, 1634, 1109 cm–1.
106.5, 128.8, 128.9, 130.5, 132.9, 154.8, 156.4.
LRMS-FAB: m/z calcd for C18H23N3O4 (M + H)+: 346.17; found:
346.20.
1H NMR (300 MHz, CDCl3): d = 1.12–1.44 (m, 12 H), 2.30 (s, 3 H),
2.37 (s, 3 H), 3.80 (s, 3 H), 4.52–4.80 (m, 2 H), 4.75–4.99 (m, 2 H),
7.15–7.32 (m, 4 H), 7.87 (s, 1 H).
13C NMR (75.47 MHz, CDCl3): d = 21.2, 21.4, 21.6, 21.9, 46.3,
51.9, 69.3, 69.7, 69.9, 126.1, 128.3, 128.8, 129.2, 129.5, 131.5,
139.2, 143.8, 155.6, 156.3, 168.1.
LRMS-FAB: m/z calcd for C22H30N2O7 (M + H)+: 435.21; found:
435.37.
Di-tert-butyl N-Acetyl-N¢-[3-(4-fluorophenyl)-2-(methoxycar-
bonyl)allyl]hydrazene-1,2-dicarboxylate (3f)
Yield: 32%.
IR (KBr): 1741 (br), 1379, 1240, 1103 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.41–1.50 (m, 18 H), 2.30 (s, 3 H),
3.81 (s, 3 H), 4.48–4.70 (m, 2 H), 7.06–7.4 7 (m, 4 H), 7.84 (s, 1 H).
Diisopropyl N¢-[3-(4-Methylphenyl)-2-(methoxycarbonyl)al-
lyl]hydrazine-1,2-dicarboxylate (4i)
Yield: 36%.
IR (KBr): 3309, 2983, 1730–1703 cm–1.
13C NMR (75.47 MHz, CDCl3): d = 25.3, 25.4, 27.7, 28.0, 28.2,
29.4, 30.8, 42.1, 43.6, 51.5, 52.1, 115.8, 126.7, 130.7, 131.9, 143.6,
153.2, 164.2, 167.9, 169.9.
LRMS-FAB: m/z calcd for C23H31FN2O7 (M + H)+: 467.21; found:
467.22.
1H NMR (300 MHz, CDCl3): d = 1.20–1.35 (m, 12 H), 2.36 (m, 3
H), 3.80 (s, 3 H), 4.64 (s, 2 H), 4.82–5.00 (m, 2 H), 6.71 (s, 1 H),
7.12–7.31 (m, 4 H), 7.84 (s, 1 H).
Di-tert-butyl N¢-[3-(4-Fluorophenyl)-2-(methoxycarbonyl)al-
lyl]hydrazine-1,2-dicarboxylate (4f)
Yield: 46%
IR (KBr): 2985, 1750, 1379, 1242, 1105 cm–1.
13C NMR (75.47 MHz, CDCl3): d = 21.2, 21.4, 21.9, 29.6, 46.3,
51.9, 69.4, 69.7, 70.0, 72.4, 126.1, 128.4, 128.9, 129.5, 131.5,
139.2, 143.8, 155.6, 168.1.
LRMS-FAB: m/z calcd for C20H28N2O6 (M + H)+: 391.18; found:
391.97
1H NMR (300 MHz, CDCl3): d = 1.42–1.46 (m, 18 H), 3.81 (s, 3 H),
4.57 (s, 2 H), 6.36 (s, 1 H), 7.02–7.42 (m, 4 H), 7.79 (s, 1 H).
Diisopropyl N-Acetyl-N¢-[3-(4-bromophenyl)-2(methoxycarbo-
nyl)allyl]hydrazine-1,2-dicarboxylate (3k)
Yield: 54%.
IR (KBr): 3334, 2983, 1788–1711, 1634, 1587 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.14–1.33 (m, 12 H), 2.36 (s, 3 H),
3.81 (s, 3 H), 4.52–4.62 (m, 2 H), 4.90–4.96 (m, 2 H), 7.15–7.55 (m,
4 H), 7.81 (s, 1 H).
13C NMR (75.47 MHz, CDCl3): d = 21.3, 21.6, 21.8, 22.0, 25.3,
29.7, 42.8, 51.7, 70.8, 71.7, 123.8, 126.8, 130.2, 133.4, 140.5,
143.7, 152.7, 154.2, 167.7, 169.5.
13C NMR (75.47 MHz, CDCl3): d = 14.1, 22.6, 28.1, 29.1, 30.7,
31.7, 52.0, 81.2, 115.4, 115.7, 127.3, 131.5, 139.0, 142.3, 155.0,
161.3, 167.9.
LRMS-FAB: m/z calcd for C21H29FN2O6 (M + H)+: 425.20; found:
425.21.
Di-tert-butyl N-Acetyl-N¢-[3-(3,4-dichlorophenyl)-2-(methoxy-
carbonyl)allyl]hydrazine-1,2-dicarboxylate (3g)
Yield: 58%.
IR (KBr): 3037, 2985, 1762, 1745, 1703, 1382, 1286, 1240 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.43–1.51 (m, 18 H), 2.36 (s, 3 H),
3.82 (s, 3 H), 4.45–4.63 (m, 2 H), 7.29 (d, J = 9 Hz, 1 H), 7.45 (d,
J = 9 Hz, 1 H), 7.60 (s, 1 H), 7.75 (s, 1 H).
HRMS (EI): m/z calcd for C21H27ClN2O7: 499.1002; found:
499.1010.
Diisopropyl N¢-[3-(4-Bromophenyl)-2-(methoxycarbonyl)al-
lyl]hydrazine-1,2-dicarboxylate (4k)
Yield: 40%.
IR (KBr): 3310, 2983, 1730–1703 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.21–1.36 (m, 12 H), 3.81 (s, 3 H),
4.57 (s, 2 H), 4.86–4.99 (m, 2 H), 6.72 (s, 1 H), 7.29–7.52 (m, 4 H),
7.77 (s, 1 H).
13C NMR (75.47 MHz, CDCl3): d = 21.7, 21.9, 46.1, 51.7, 69.5,
70.6, 128.4, 128.8, 129.8, 131.0, 133.7, 135.3, 142.4, 155.8, 156.4,
167.8.
13C NMR (75.47 MHz, CDCl3): d = 22.7, 25.3, 26.9, 27.7, 27.8,
42.2, 52.3, 81.5, 83.8, 128.0, 129.0, 130.5, 131.6, 138.7, 142.2,
151.7, 153.2, 167.2, 169.9.
LRMS-FAB calcd for C23H30Cl2N2O7 (M + H)+: 517.14; found:
517.15.
Di-tert-butyl N¢-[3-(3,4-Dichlorophenyl)-2-(methoxycarbon-
yl)allyl]hydrazine-1,2-dicarboxylate (4g)
Yield: 30%.
IR (KBr): 3415, 2975, 1751, 1741, 1712, 1481, 1381, 1250, 1105
cm–1.
1H NMR (300 MHz, CDCl3): d = 1.45 (s, 18 H), 3.82 (s, 3 H), 4.54
(s, 2 H), 6.4 (s, 1 H), 7.44 (d, J = 9 Hz, 2 H), 7.52 (s, 1 H), 7.71 (s,
1 H).
13C NMR (75.47 MHz, CDCl3): d = 14.2, 19.4, 20.9, 22.6, 28.1,
52.2, 81.0, 129.3, 130.5, 131.2, 132.8, 134.5, 140.7, 154.8, 161.3,
170.8.
HRMS (EI): m/z calcd for C19H25BrN2O6: 457.0896; found:
457.0912.
Acknowledgment
V.N. acknowledges the DST support in the form of a Raja Ramanna
Fellowship. Financial assistance to S.C.M. and B.A.T. from the
Council of Scientific and Industrial Research (CSIR), Government
of India, is acknowledged. The authors also thank Mrs. Saumini
Mathew for recording NMR spectra and Mrs. S. Viji for mass spec-
tral analysis.
LRMS-FAB: m/z calcd for C21H28Cl2N2O6 (M + H)+: 475.13;
found: 475.02.
Synthesis 2009, No. 11, 1829–1833 © Thieme Stuttgart · New York

PAPER
Novel Strategy for the Synthesis of b-Amino Acid Derivatives
1833
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2005, 7, 5139.
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Synthesis 2009, No. 11, 1829–1833 © Thieme Stuttgart · New York