Toward a novel approach to bis-β-lactam synthesis using Vilsmeier reagent as an efficient entity via Staudinger cycloaddition reaction

Article abstract of DOI:10.1002/jhet.455

A facile synthesis of bis-β-lactams has been executed using chloromethylenedimethylammonium chloride (Vilsmeier reagent), prepared easily from N,N-dimethylformamide and phosphorus oxychloride. It works out as a versatile acid activator reagent for the dir

Full text of DOI:10.1002/jhet.455

1454
Toward a Novel Approach to Bis-b-Lactam Synthesis Using
Vilsmeier Reagent as an Efficient Entity via Staudinger
Cycloaddition Reaction
Vol 47
Jyotsna Meshram,* Parvez Ali, and Vandana Tiwari
Department Of Chemistry, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur,
Maharashtra 440033, India
*E-mail: drjsmeshram@rediffmail.com
Received November 10, 2009
DOI 10.1002/jhet.455
Published online 24 August 2010 in Wiley Online Library (wileyonlinelibrary.com).
A facile synthesis of bis-b-lactams has been executed using chloromethylenedimethylammonium
chloride (Vilsmeier reagent), prepared easily from N,N-dimethylformamide and phosphorus oxychloride.
It works out as a versatile acid activator reagent for the direct [2 þ 2] ketene–imine cycloaddition of
substituted acetic acid and bis-imines in one-pot synthesis under mild conditions. Thus, this method has
been proved as a high yielding, efficient, and cheap protocol for bis-b-lactam synthesis.
J. Heterocyclic Chem., 47, 1454 (2010).
INTRODUCTION
generated in situ from acyl halides in the presence of
tertiary amines [10]. In addition to the utilization of acyl
halides, a variety of other methods have been described
to activate carboxylic acids [11]. These methods are
conventionally useful when the acid halides are not
commercially available, difficult to prepare or when
they are unstable. Some acid activating agents include
1,1-carbonyldi-imidazole [12], triphosgene [13], ethyl
chloroformate [14], trifluoroacetic anhydride [15], p-tol-
uenesulfonyl chloride [16], phosphorus-derived reagents
[17], cyanuric chloride [18], the Mukaiyama reagent
[19], and acetic anhydride [20].
The b-lactam skeleton is the key structural unit of the
most widely employed b-lactam antibiotics [1]. The
constant need for new drugs displaying broader antibac-
terial activity and the necessity for new b-lactam antibi-
otics to combat the microorganisms that have built up
resistance against the most traditional drugs [2] have
maintained the interest of organic chemists in b-lactams
for decades. In addition to its use in the synthesis of va-
riety of b-lactam antibiotics, the b-lactam skeleton has
been recognized as a useful building block by exploiting
its strain energy associated with four member ring [3].
Efforts have been made in exploring such new aspects
of b-lactam chemistry using pure b-lactams as versatile
intermediates for organic syntheses [4]. Ojima et al. [5]
have shown the utility of bis-b-lactams for the synthesis
of peptides. The synthesis of bis-b-lactams, in general,
has been reported by a step-wise construction of b-lac-
tam rings [6]. In continuation of our work on synthesis
of bis-b-lactams [7], we were interested in building bis-
b-lactams from bis-imines using the Staudinger cycload-
dition reaction.
Herein this communication, we report the synthesis of
bis-b-lactams using Vilsmeier reagent. Chloromethylene-
dimethylammonium chloride (Vilsmeier reagent) has
been known as a formylating agent [21]. It has also
emerged as an efficient synthetic auxiliary for the syn-
thesis of some important class of organic compounds.
This white solid is easily synthesized by reaction of
N,N-dimethylformamide (DMF) and chlorinating agents
such as POCl3 or SOCl2 [22]. But in our methodology,
we have generated this reagent in situ using DMF and
POCl3 in dichloromethane as reported [23]. This reagent
was reported for the synthesis of monobactams by Jar-
rahpour and Zarei [24]. We have extended its applicabil-
ity in the synthesis of bis b-lactams by generating it
in situ. In this article, we wish to describe the versatility
and utility of the Vilsmeier reagent for the activation of
carboxylic acids in bis-b-lactam synthesis under simple
Among the various methods available for the synthe-
sis of b-lactams, the Staudinger cycloaddition reaction
(ketene–imine cycloaddition reaction) is the most widely
used [8] mainly because of the simplicity in reaction
procedures. This method has been used for the synthesis
of a large number of monocyclic, bicyclic, tricyclic, and
spirocyclic b-lactams [9]. The ketenes are commonly
C
V
2010 HeteroCorporation

November 2010
Toward a Novel Approach to Bis-b-Lactam Synthesis Using Vilsmeier
Reagent as an Efficient Entity via Staudinger Cycloaddition Reaction
1455
Scheme 1. Synthesis of bis-imines 2a–h.
and mild conditions. It has proved to be a high yielding
protocol for the synthesis.
added to a solution of mixture of acid, imines, and trie-
thylamine in CH2Cl2 between 0 and ꢀ5ꢁC, and the reac-
tion mixture was stirred at room temperature for 10 h.
The usual work-up and then crystallization from hot
methanol gave pure bis-b-lactams 5a–h in high yields.
We found that this method was very efficient, simple,
and clean. The DMF and triethylammonium salt are two
by-products, which were removed by simple aqueous
work-up. In all cases the cycloaddition afforded only
cis, cis bis-b-lactams 5a–h.
RESULTS AND DISCUSSION
We selected toluene-2,4-diamine for the preparation
of various bis-imines from different aldehydes and this
imine were used for the construction of bis-b-lactams.
The bis-imines 3a–h were prepared by refluxing tolu-
ene-2,4-diamine with 2 mol equivalent of aldehydes
(benzaldehyde, 2-hydroxybenzaldehyde, 4-hydroxyben-
zaldehyde, 2-nitrobenzaldehyde, 3-nitrobenzaldehyde,
4-methoxybenzaldehyde, 2-chlorobenzaldehyde, 4-chlor-
obenzaldehyde, and 4-methoxy-benzaldehyde in ethanol
for about 1 to 1.5 h as shown in Scheme 1 according to
known method [23]. Crude bis-imines were recrystal-
lized with hot methanol.
The cis steriochemistry for bis-b-lactam 5a–h was
1
assigned on the basis of H NMR spectral analysis. The
1H NMR spectra showed two doublets between 5.24 and
5.56 ppm for cis-b-lactam ring protons (J ¼ 4.6 to 4.8
Hz for cis b-lactam protons). The absence of ACH¼¼N
protons in 5a–h show the azetidinone ring formation.
The IR spectra of the bis-imines 3a–h were compared
with those of the bis-b-lactams to draw conclusion on
cycloaddition. There were some guide peaks in the spec-
trum of the bis-imines and bis-lactams, which were
helpful in achieving this goal. The position and the
intensities of these peaks are expected to change
upon cycloaddition. In the spectrum of bis-imines, the
characteristic absorption around 1618–1650 cmꢀ1 can
be assigned to (AC¼¼N) azomethine linkage, which
Chloromethylenedimethylammonium chloride 4 was
prepared from DMF and phosphorus oxychloride in
dry CH2Cl2. We have successfully employed the Vils-
meier reagent for the one-step cycloaddition reaction of
various imines 3a–h and substituted phenoxyacetic acid
to obtain bis-b-lactams 5a–h (Scheme 2). Solution
of Chloromethylenedimethylammonium chloride 4 was
Scheme 2. General synthesis of bis-b-lactam products 5a–h.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

1456
J. Meshram, P. Ali, and V. Tiwari
Vol 47
Scheme 3. Approaches in the formation of cis, cis bis-b-lactam.
EXPERIMENTAL
disappears in the spectrum of the bis-b-lactams confirm-
ing the cycloaddition. In the spectrum of bis-lactams,
the characteristic absorption around 1750–1700 cmꢀ1
can be assigned to (AC¼¼O) linkage. The mass spectra
of these compounds displayed a molecular ion peak at
their respective m/z values, which are corresponding
well with the respective molecular mass. All the com-
pounds have given the satisfactory elemental analysis.
We believe that mono-b-lactam is initially formed by
the reaction of the most stable bis-imine (I approach)
with ketene. The approach of the ketene in the Stau-
dinger cycloaddition reaction is such that the steric
interaction between the aryl group of the imine and phe-
noxy group of the ketene is minimum in the transition
state (Scheme 3) resulting in the formation of cis-b-lac-
tam. However, the formation of trans-b-lactam is unfav-
orable due to severe steric interaction between the aryl
group of imine and phenoxy group of ketene in the tran-
sition state. The mono b-lactam further undergoes cyclo-
addition reaction with the second molecule of ketene to
give bis-b-lactam (Scheme 3). The approach of the sec-
ond ketene towards the imine is from the opposite site
of the preformed azetidinone ring to give bis-b-lactam
5a. In this approach, the ketenes are generated directly
from the carboxylic acid using Vilsmeier reagent instead
of acid chloride. Thus, the Staudinger reaction of imines
with carboxylic acids using Vilsmeier reagent 4 as an
activator proceeded smoothly under milder reaction con-
ditions. As acid chlorides are usually unstable, this
approach is quite practical as starting carboxylic acid
can be easily handled and stored as compared to
respected acid chloride.
The solvents and reagents used in the synthetic work were of
analytical grade obtained from Qualigens India and were purified
by distillation or crystallization, where necessary and their boil-
ing or melting points were compared with the available literature
values. Melting points were determined in open capillaries and
are uncorrected. 1H NMR spectra were recorded on a Perkin
Elmer FT NMR Cryo-magnet Spectrometer 400 MHz (Bruker)
instrument using tetramethylsilane (TMS) as an internal standard
and DMSO-d6 as a solvent. Chemical shifts are given in parts
per million (ppm). Infrared spectra were recorded on Schimadzu-
IR Prestige 21. Mass spectra were recorded on a Waters Micro-
mass Q-T of Micro spectrometer. The reactions were monitored,
and the purity of products was checked out on pre-coated TLC
plates (Silica gel 60 F254, Merck), visualizing the spots under
ultraviolet light and iodine chamber.
General procedure for the preparation of bis-imines 3a–
h. A mixture of freshly distilled benzaldehyde (2.78 g, 26.3
mmol) and toluene-2,4-diamine (2.20 g, 17.5 mmol) in ethanol
(30 mL) was refluxed for 1–1.5 h. The completion of the reac-
tion was monitored by thin layer chromatography. After disap-
pearance of the starting materials, the reaction mixture was
allowed to attain the room temperature during which solid pre-
cipitated out. It was filtered out and recrystallized from hot
methanol to afford 3a as yellow crystalline solid. Following
this procedure, bis-imines 3b–h were prepared in excellent
yield. All the bis-imines are well known in the refs. 25–27 and
identified by comparison of their physical and spectral data.
A typical procedure for the preparation of bis-b-lactams
5a–h. In a 100 mL Round Bottom Flask, (1.0 g, 3.35 mmol)
bis-imine 3a was charged followed by (10 mL) dichlorome-
thane. To it (1.48 g, 6.70 mmol), 2,4-dichlorophenoxyacetic
acid followed by (1.35 g, 13.40 mmol) triethylamine was
charged. It was chilled to ꢀ5ꢁC. To a separate 50 mL Round
Bottom Flask, (1.2 g, 8.04 mmol), POCl3 in (10 mL) dichloro-
methane was charged. The solution was cooled to 10ꢁC and a
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

November 2010
Toward a Novel Approach to Bis-b-Lactam Synthesis Using Vilsmeier
Reagent as an Efficient Entity via Staudinger Cycloaddition Reaction
1457
1
solution of DMF (0.50 g, 6.7 mmol) in 5 mL dichloromethane
was added over 10 min maintaining the temperature between
10 and 15ꢁC. When the addition was complete, the mixture
was allowed to stir at room temperature for 30 min. This Vils-
meier solution was then added gradually to the above prepared
bis-imine solution over 15 min, maintaining the temperature
between 0 and ꢀ5ꢁC. After the addition was complete, the
reaction mixture was allowed to warm up to room temperature
and stirred for 10 h. The reaction mixture was then washed
with water (2 ꢂ 20 mL), saturated sodium bicarbonate solution
(20 mL) and saturated brine solution (20 mL). The organic
layer was then dried over anhydrous Na2SO4 and concentrated
to give the crude bis-b-lactams. It was recrystallized from hot
methanol to give pure bis-b-lactams. Following this procedure
other b-lactams 5b–h were prepared.
1765, 1365 cmꢀ1. H NMR (DMSO-d6): 2.13 (s, 3H, ACH3),
6.75–8.10 (m, 17H, Ar), 5.26 (d, 1H, J ¼ 4.7 Hz), 5.51 (d,
1H, J ¼ 4.7 Hz), 5.26 (d, 1H, J ¼ 4.6 Hz), 5.55 (d, 1H, J ¼
4.6 Hz). MS: m/z: 794 (Mþ, 100%), 795 (65%), 796 (32%).
Anal. Calc. for C37H24Cl4N4O8: C, 55.94; H, 3.05; Cl, 17.85;
N, 7.05; O, 16.11. Found: C, 55.90; H, 3.11; Cl, 17.83; N,
7.09; O, 16.16.
3-(2,4-Dichlorophenoxy)-1-(3-(3-(2,4-dichlorophenoxy)-2-oxo-
4-(4-methoxyphenyl)azetidin-1-yl)-4-methyl
phenyl)-4-(4-
methoxyphenyl)azetidin-2-one 5(f). This compound was
obtained as brown solid, 69%, m.p. 206–208ꢁC, IR (KBr):
3120, 2965, 2970, 1755, 1365, 1040 cmꢀ1. H NMR (DMSO-
1
d6): 2.25 (s, 3H, ACH3), 3.85 (s, 3H, AOCH3), 6.93–7.60 (m,
17H, Ar), 5.45 (d, 1H, J ¼ 4.7), 5.50 (d, 1H, J ¼ 4.7 Hz),
5.28 (d, 1H, J ¼ 4.6 Hz), 5.66 (d, 1H, J ¼ 4.6 Hz). MS: m/z:
764 (Mþ, 100%), 765 (61%), 766 (23%). Anal. Calc. for
C39H30Cl4N2O6: C, 61.27; H, 3.96; Cl, 18.55; N, 3.66; O,
12.56. Found: C, 61.25; H, 3.86; Cl, 18.40; N, 3.90; O, 12.60.
3-(2,4-Dichlorophenoxy)-1-(3-(3-(2,4-dichlorophenoxy)-2-oxo-
4-(2-chlorophenyl)azetidin-1-yl)-4-methyl phenyl)-4-(2-chloro-
phenyl)azetidin-2-one 5(g). This compound was obtained as
white solid, 71%, m.p. 189–190ꢁC, IR (KBr): 3122, 2965,
3-(2,4-Dichlorophenoxy)-1-(3-(3-(2,4-dichlorophenoxy)-2-
oxo-4-phenylazetidin-1-yl)-4-methyl phenyl)-4-phenylazeti-
din-2-one 5(a). This compound was obtained as white solid,
81%, m.p. 193–194ꢁC, IR (KBr): 3120, 2965, 2970, 1755,
1
1365 cmꢀ1. H NMR (DMSO-d6): 2.34 (s, 3H, ACH3), 6.80–
7.62 (m, 19H, Ar), 5.25 (d, 1H, J ¼ 4.7 Hz), 5.51 (d, 1H, J ¼
4.7 Hz), 5.26 (d, 1H, J ¼ 4.6 Hz), 5.56 (d, 1H, J ¼ 4.6 Hz).
MS: m/z: 704 (Mþ, 100%), 702 (71%), 706 (52%). Anal. Calc.
for C37H26Cl4N2O4: C, 63.09; H, 3.72; Cl, 20.13; N, 3.98; O,
9.09. Found: C, 63.12; H, 3.75; Cl, 20.10; N, 3.96; O, 9.12.
3-(2,4-Dichlorophenoxy)-1-(3-(3-(2,4-dichlorophenoxy)-2-oxo-
4-(2-hydroxyphenyl)azetidin-1-yl)-4-methyl phenyl)-4-(2-hydrox-
yphenyl)azetidin-2-one 5(b). This compound was obtained as
light yellow solid, 79%, m.p. 201–203ꢁC, IR (KBr): 3300,
1
2970, 1765 cmꢀ1. H NMR (DMSO-d6): 2.20 (s, 3H, ACH3),
6.78–7.60 (m, 17H, Ar), 5.25 (d, 1H, J ¼ 4.7), 5.50 (d, 1H, J
¼ 4.7 Hz), 5.27 (d, 1H, J ¼ 4.6 Hz), 5.56 (d, 1H, J ¼ 4.6
Hz). MS: m/z: 773 (Mþ, 100%), 774 (73%), 776 (30%). Anal.
Calc. for C37H24Cl6N2O4: C, 57.43; H, 3.13; Cl, 27.51; N,
3.52; O, 28.09. Found: C, 57.45; H, 3.15; Cl, 27.52; N, 3.50;
O, 28.10.
3122, 2960, 2965, 1760, 1368 cmꢀ1
.
1H NMR (DMSO-d6):
3-(2,4-Dichlorophenoxy)-1-(3-(3-(2,4-dichlorophenoxy)-2-oxo-
4-(4-chlorophenyl)azetidin-1-yl)-4-methyl phenyl)-4-(4-chloro-
phenyl)azetidin-2-one 5(h). This compound was obtained as
white solid, 76%, m.p. 211–212ꢁC, IR (KBr): 3130, 2971, 2975,
2.33 (s, 3H, ACH3), 5.25 (d, 1H, J ¼ 4.7 Hz), 5.51 (d, 1H, J
¼ 4.7 Hz), 5.26 (d, 1H, J ¼ 4.6 Hz), 5.56 (d, 1H, J ¼ 4.6
Hz), 6.85–7.72 (m, 17H, Ar), 12.10–12.20 (s, 2H, AOH). MS:
m/z: 736 (Mþ, 100), 737 (68%), 738 (30%). Anal. Calc. for
C37H26Cl4N2O6: C, 60.35; H, 3.56; Cl, 19.26; N, 3.80; O,
13.0. Found: C, 60.38; H, 3.53; Cl, 19.29; N, 3.83; O, 13.10.
3-(2,4-Dichlorophenoxy)-1-(3-(3-(2,4-dichlorophenoxy)-2-oxo-
4-(4-hydroxyphenyl)azetidin-1-yl)-4-methyl phenyl)-4-(4-hydrox-
yphenyl)azetidin-2-one 5(c). This compound was obtained as
light yellow solid, 82%, m.p. 185–186ꢁC, IR (KBr): 3300,
1768 cmꢀ1 1H NMR (DMSO-d6): 2.22 (s, 3H, ACH3), 6.78–
.
8.10 (m, 17H, Ar), 5.24 (d, 1H, J ¼ 4.7 Hz), 5.54 (d, 1H, J ¼
4.7 Hz), 5.30 (d, 1H, J ¼ 4.6 Hz), 5.58 (d, 1H, J ¼ 4.6 Hz).
MS: m/z: 773 (Mþ, 100%), 774 (76%), 776 (34%). Anal. Calc.
for C37H24Cl6N2O4: C, 57.43; H, 3.13; Cl, 27.51; N, 3.52; O,
28.09. Found: C, 57.50; H, 3.21; Cl, 27.55; N, 3.61; O, 28.15.
3120, 2962, 2964, 1758, 1366 cmꢀ1 1H NMR (DMSO-d6):
.
Acknowledgments. The authors acknowledge the financial sup-
port from University Grant Commission [F-33-301/2007(SR)],
New Delhi. They are grateful to SAIF Punjab University, Chandi-
garh for the help in undertaking NMR, Mass spectra and Depart-
ment of pharmacy, Nagpur University, Nagpur for undertaking
IR spectra.
2.33 (s, 3H, ACH3), 5.24 (d, 1H, J ¼ 4.7 Hz), 5.54 (d, 1H, J
¼ 4.7 Hz), 5.26 (d, 1H, J ¼ 4.6 Hz), 5.60 (d, 1H, J ¼ 4.6
Hz), 6.83–7.74 (m, 17H, Ar), 12.12 (s, 1H, AOH). MS: m/z:
736 (Mþ, 100), 737 (73%), 738 (42%). Anal. Calc. for
C37H26Cl4N2O6: C, 60.35; H, 3.56; Cl, 19.26; N, 3.80; O,
13.0. Found: C, 60.38; H, 3.53; Cl, 19.29; N, 3.83; O, 13.10.
3-(2,4-Dichlorophenoxy)-1-(3-(3-(2,4-dichlorophenoxy)-2-
oxo-4-(2-nitrophenyl)azetidin-1-yl)-4-methyl phenyl)-4-(2-
nitrophenyl)azetidin-2-one 5(d). This compound was obtained
as yellow solid, 75%, m.p. 190–191ꢁC, IR (KBr): 3122, 2975,
REFERENCES AND NOTES
[1] (a) Durkheimer, W.; Blumbach, J.; Lattrell, R.; Scheune-
mann, K. H. Angew Chem Int Ed Engl 1985, 24, 180; (b) Morin, R.
B.; Gorman, M., Eds. Chemistry and Biology of b-Lactam Antibiotics;
Academic Press: New York, 1982; Vols. 1–3; (c) Southgate, R. Con-
temp Org Synth 1994, 1, 417.
2970, 1756, 1366 cmꢀ1 1H NMR (DMSO-d6): 2.12 (s, 3H,
.
ACH3), 6.79–8.03 (m, 17H, Ar), 5.26 (d, 1H, J ¼ 4.7 Hz), 5.51 (d,
1H, J ¼ 4.7 Hz), 5.26 (d, 1H, J ¼ 4.6 Hz), 5.55 (d, 1H, J ¼ 4.6
Hz). MS: m/z: 794 (Mþ, 100%), 795 (62%), 796 (26%). Anal.
Calc. for C37H24Cl4N4O8: C, 55.94; H, 3.05; Cl, 17.85; N, 7.05; O,
16.11. Found: C, 55.92; H, 3.10; Cl, 17.83; N, 7.08; O, 16.13.
3-(2,4-Dichlorophenoxy)-1-(3-(3-(2,4-dichlorophenoxy)-2-oxo-
4-(3-nitrophenyl)azetidin-1-yl)-4-methyl phenyl)-4-(3-nitrophe-
nyl)azetidin-2-one 5(e). This compound was obtained as yellow
solid, 72%, m.p. 214–215ꢁC, IR (KBr): 3118, 2971, 2969,
[2] Page, M. I., Ed. The Chemistry of b-Lactams; Chapman &
Hall: London, 1992.
[3] (a) Manhas, M. S.; Amin, S. G.; Bose, A. K. Heterocycles
1976, 5, 669; (b) Manhas, M. S.; Wagle, D. R.; Chiang, J. Hetero-
cycles 1988, 27, 1755.
[4] Palomo, C.; Aizpurua, J. M.; Ganboa, I.; Oiarbide, M. Curr
Med Chem 2004, 11, 1837.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

1458
J. Meshram, P. Ali, and V. Tiwari
Vol 47
[5] (a) Ojima, I.; Hatanaka, N.; Yoda, N.; Abe, R.; Yatabe, M.;
[14] Bose, A. K.; Manhas, M. S.; Amin, S. G.; Kapur, J. C.;
Kreder, J.; Mukkavilli, L.; Ram, B.; Vincent, J. E. Tetrahedron Lett
1979, 2771.
Yanashita, M. In Peptide Chemistry; Sakakibara, S., Ed.; Protein
Research Foundation: Osaka, 1983; p 29; (b) Yamashita, M.; Abe, R.;
Hatanaka, N.; Ojima, I. In Peptide Chemistry; Sakakibara, S., Ed.; Pro-
tein Research Foundation: Osaka, 1983; p 85.
[15] Bose, A. K.; Kapur, J. C.; Sharma, S. D.; Manhas, M. S.
Tetrahedron Lett 1973, 2319.
[6] (a) Ojima, I.; Zhao, M.; Yamato, T.; Nakahashi, K.; Yama-
shita, M.; Abe, R. J Org Chem 1991, 56, 526; (b) Ojima, I.; Nakaha-
shi, K.; Branstadter, S. M.; Hatanaka, N. J Am Chem Soc 1987, 109,
1798.
[16] (a) Jarrahpour, A.; Zarei, M. Molecules 2007, 12, 2364;
(b) Miyake, M.; Tokutake, N.; Kirisawa, M. Synthesis 1983, 833.
[17] (a) Bhalla, A.; Venugopalany, P.; Bari, S. S. Tetrahedron
2006, 62, 8291; (b) Farouz-Grant, F.; Miller, M. J. Bioorg Med Chem
Lett 1993, 3, 2423; (c) Cossio, F. P.; Lecea, B.; Palomo, C. J Chem
Soc Chem Commun 1987, 1743.
[7] Parvez, A.; Jyotsna, M.; Hamid, Y.; Taibi, H. Phosphorus
Sulfur Silicon Relat Elem, to appear.
[8] (a) Staudinger, H. Liebigs Ann Chem 1907, 356, 51; (b)
George, G. I.; Ravikumar, V. T. In The Organic Chemistry of b-Lac-
tams; George, G. I., Ed.; VCH: New York, 1993; p 295; (c) Palomo, C.;
Aizpurua, J. M.; Ganboa, I.; Oiarbide, M. Eur J Org Chem 1999, 3223.
[9] (a) Morin, R. B.; Gorman, M. Chemistry and Biology
of b-Lactam Antibiotics; Academic Press: New York, NY, 1982; (b)
Jarrahpour, A. A.; Shekarriz, M.; Taslimi, A. Molecules 2004, 9, 29; (c)
Hakimelahi, G. H.; Jarrahpour, A. A. Helv Chim Acta 1989, 72, 1501.
[10] (a) Van der Steen, F. H.; Van Koten, G. Tetrahedron 1991,
47, 7503; (b) Jarrahpour, A.; Alvand, P. Iran J Sci Technol Trans A
2007, 31, 17; (c) Jarrahpour, A. A.; Shekarriz, M.; Taslimi, A. Mole-
cules 2004, 9, 939.
[18] Manhas, M. S.; Bose, A. K.; Khajavi, M. S. Synthesis
1981, 209.
[19] (a) Matsui, S.; Hashimoto, Y.; Saigo, K. Synthesis 1998,
1161; (b) George, G. I.; Mashava, P. M.; Guan, X. Tetrahedron Lett
1991, 32, 581.
[20] Croce, P. D.; La Rosa, C. Tetrahedron Asymmetry 1999,
10, 1193.
[21] Campaigne, E.; Archer, W. L. J Am Chem Soc 1953, 75, 141.
[22] Eilingsfeld, H.; Seefelder, M.; Weidenger, H. Angew Chem
1969, 72, 836.
[23] Dyer, U. C.; Henderson, D. A.; Tiffin, P. D. Org Process
Res Dev 2002, 6, 311.
[11] George, G. I., Ed. The Organic Chemistry of b-Lactams;
VCH: New York, NY, 1993.
[24] Jarrahpour, A.; Zarei, M. Tetrahedron lett 2007, 48, 8712.
[25] Mederos, A.; Manrique, F.; Medina, A. An Quim B 1980, 76, 33.
[26] Roman, B. Coord Chem Rev 2004, 248, 757.
[27] Meshram, J.; Parvez, A.; Tiwari, V. Green Chem Lett Rev,
to appear.
[12] Nahmany, M.; Melman, A. J Org Chem 2006, 71, 5804.
[13] Deshmukh, A. R. A. S.; Krishnaswamy, D.; Govande, V. V.;
Bhawal, B. M.; Gumaste, V. K. Tetrahedron 2002, 58, 2215.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet