Reaction cascades initiated by nucleophilic attack of heteropentalene mesomeric betaine and nitrogen-rich mesoionic tetrazolium-5-amides on electron-deficient unsaturated compounds. Synthesis of novel heterocyclic systems.

Article abstract of DOI:10.1039/b211000h

The reactions of heteropentalene mesomeric betaine 1 and nitrogen-rich mesoionic tetrazolium-5-amides 4, 11 and 16-18 with electron-deficient unsaturated compounds have been studied. Novel heterocyclic systems, tetrazolo[4,5-a][1,7]benzodiazonine inner sa

Full text of DOI:10.1039/b211000h

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Reaction cascades initiated by nucleophilic attack of
heteropentalene mesomeric betaine and nitrogen-rich mesoionic
tetrazolium-5-amides on electron-deficient unsaturated compounds.
Synthesis of novel heterocyclic systems†
Shuki Araki,* Masashi Kuzuya, Kenji Hamada, Masatoshi Nogura and Nayumi Ohata
Department of Applied Chemistry, Nagoya Institute of Technology, Gokiso-cho, Showa-ku,
Nagoya 466-8555, Japan. E-mail: araki@ach.nitech.ac.jp; Fax: ϩ81-52-735-5206
Received 7th November 2002, Accepted 24th January 2003
First published as an Advance Article on the web 14th February 2003
The reactions of heteropentalene mesomeric betaine 1 and nitrogen-rich mesoionic tetrazolium-5-amides 4, 11 and
16–18 with electron-deficient unsaturated compounds have been studied. Novel heterocyclic systems, tetrazolo[4,5-
a][1,7]benzodiazonine inner salt 2 and 3-oxo-3,7-dihydro-2H-pyrazolo[3,4-b]pyridine 5, have been synthesized by the
reactions of dimethyl acetylenedicarboxylate with 1 and tetrazolium-5-anilide 4, respectively, and fully characterized
by X-ray crystallography. It has been found that the reactions of other tetrazolium-5-amides are also initiated by the
nucleophilic addition of the electron-rich amide nitrogen to the electron-deficient unsaturated compounds.
product is a 1 : 2 adduct of 1 and DMAD. The structure
of 2 was unambiguously determined by X-ray crystallography,
Introduction
Heteropentalene mesomeric betaines are isoconjugate with the
which reveals the unique tricyclic tetrazolo[1,5-a][1,7]benzo-
pentalenyl dianion which cannot be represented by covalent
diazonine system (Fig. 1). The nine-membered ring is not
Kekulé structures.1 Mesoionic compounds are five-membered
planar but distorted in two different directions; hence two
heterocycles which cannot be represented satisfactorily by any
crystallographically independent molecules exist in the crystal.
one covalent or polar canonical structure.2 Both types of hetero-
cycle can only be represented by the hybrid of several dipolar
The compound 2 can be best expressed by the tetrazolium-
methylide inner salt structure, in which the negative charge on
structures and, owing to their interesting electronic structures,
C-4 is associated with the methoxycarbonyl group attached
they have been extensively studied from theoretical, synthetic,
and practical standpoints. As these compounds are highly
to this carbon. The high field chemical shift of C-4 (53.4 ppm)
in the 13C NMR spectrum supports this formulation.
polarized dipoles, among their chemical transformations, the
reactions with electron-deficient unsaturated compounds are
particularly intriguing and, indeed, several new heterocyclic
systems with novel ring structures have hitherto been con-
structed via 1,3-dipolar cycloaddition reactions.3
In our continuing studies on tetrazole mesoionic systems,
we recently synthesized heteropentalene mesomeric betaine 1
by the photolysis of a 5-azido-1,3-diphenyltetrazolium salt.4
Here we disclose a series of addition reactions of 1, as well as
of related nitrogen-rich mesoionic heterocycles, to electron-
deficient unsaturated compounds which give novel heterocyclic
systems.
Results and discussion
(a) Reactions of 2-phenyl-1H-tetrazolo[1,5-a]benzimidazolium
inner salt (1)
Fig.
1
X-ray crystal structure of compound 2. The two
Heteropentalene mesomeric betaines are classified into four
categories (types A–D) based on their electronic arrangements.1
Most of the known heteropentalene mesomeric betaines are of
types A and B; types C and D are rare. The compound 1 is a
type C system. The reaction of 1 with dimethyl acetylenedi-
carboxylate (DMAD) was examined first. When 1 was stirred
with excess DMAD without solvent, the reaction proceeded
smoothly and red crystals of 2 were obtained in 78% yield after
recrystallization. Although the mass spectrum did not show
the molecular ion peak, the nitrogen-lost fragment ion peak
(Mϩ Ϫ N2) and the elemental analysis data indicate that this
crystallographically independent molecules are shown.
The reaction can be considered to proceed as depicted in
Scheme 1. The electron-rich amide nitrogen reacts nucleo-
philically with two molecules of DMAD to give the tetracyclic
intermediate, whose C-5–Nexo bond is cleaved to regenerate the
stable 1,3-diaryl-5-substituted tetrazolium system. It is noted
that no 1 : 1 adduct (seven-membered ring product) was found
in the reaction mixture.
Compound 1 was next subjected to reaction with benzyne.
Benzyne, generated in situ in refluxing dichloromethane, reacted
readily to give a yellow solid. The characteristic absorption at
1688 cmϪ1 in the IR spectrum suggests that this product is a
tetrazolium-5-olate derivative. The presence of an NH group is
† Electronic supplementary information (ESI) available: synthesis of
4b; reactions of 11 and 17 with electron-deficient unsaturated com-
pounds; alternative synthesis of 19 from 20. See http://www.rsc.org/
suppdata/ob/b2/b211000h/
1
also indicated by the IR and H NMR spectra. The structure
O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 9 7 8 – 9 8 3
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
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rearrangement to furnish the product 3. The reactions of 1
with other electrophiles such as tetracyanoethylene, ethyl
propiolate, dimethyl [1,2,4,5]tetrazine-3,6-dicarboxylate, di-
benzoylacetylene, and dimethyl azodicarboxylate were also
examined; however, no addition products were obtained from
these reactions.
(b) Reactions of 1,3-diphenyltetrazolium-5-anilide (4a)
The reaction of 4a with DMAD in acetonitrile proceeded
smoothly at room temperature. Column chromatographic
separation of the reaction mixture gave the purple compound
5a (12%) and olate 6a (27%), together with a trace amount of
naphthalenetetracarboxylate 7 (Scheme 3). The compound 5a
has a molecular formula (C24H19N3O7) which corresponds to
a loss of PhN2 and MeO groups from a 1 : 2 adduct of 4a
and DMAD. The structure was assigned as the pyrazolo[3,4-b]-
pyridine derivative 5a. In order to determine which phenyl
groups of 4a correspond to the two phenyl groups of 5a, a
labeling experiment was performed. The three phenyl groups
of 4a were labeled; i.e., 3-phenyl-1-(4-tolyl)tetrazolium-5-(4-
ethyl)anilide (4b) was synthesized and subjected to the same
reaction. From this reaction, olate 6b (43%) and pyrazolo-
[3,4-b]pyridine 5b (5%) were isolated. A naphthalene derivative
corresponding to 7 was not obtained from this reaction;
instead, maleate 8 was isolated in 2% yield. The formation of 7
and 8 could be attributed to phenyl (or 4-tolyl) radical derived
from the aryldiazonium salts. The structure of 5b was deter-
mined crystallographically. The crystals grown from dichloro-
methane–hexane contain four 5b molecules and two CH2Cl2
molecules in the unit cell. These 5b molecules are slightly dif-
ferent from each other in the tilting angle between the pyrazolo-
pyridine ring plane and the substituent groups, though they
have essentially identical geometries. One of these four mole-
cules is depicted in Fig. 2. The phenyl ring at N-2 lies in almost
the same plane as the pyrazolo[3,4-b]pyridine ring, whereas the
4-ethylphenyl group at N-7 is essentially perpendicular. It is
evident that the tolyl group at the N-1 position of 4b is not
incorporated into 5b. The most plausible reaction mechanism is
shown in Scheme 4. Again, the reaction is initiated by nucleo-
philic attack of the exocyclic nitrogen of 4 on DMAD. In con-
trast to the case of 1, the intermediate undergoes a cleavage and
degradation of the tetrazolium ring to furnish the novel bicyclic
system 5. Only a few examples of this ring system have been
previously prepared, e.g., by the condensation of 5-amino-2,4-
dihydro-3H-pyrazol-3-one with β-carbonyl compounds.5
Scheme 1
was eventually deduced to be 1-(2-anilinophenyl)-3-phenyl-
tetrazolium-5-olate (3) based on the elemental analysis and
spectral data. A plausible mechanism for the formation of 3 is
illustrated in Scheme 2. The electrophilic addition of benzyne to
the electron-rich exocyclic nitrogen of 1 yields the N-phenylated
tricyclic intermediate, which is nucleophilically attacked by
hydroxide ion followed by a ring cleavage and prototropic
Fig. 2 X-ray crystal structure of compound 5b.
The formation of olate 6 from 4 was unexpected. Similar
reaction of 4a with dibenzoylacetylene (4 equiv.) gave olate 6a
in 45% yield. When this reaction was carried out after the
addition of a small amount of H218O, the resulting olate 6a
contained 21% 18O by mass spectroscopy. Therefore, the
Scheme 2
O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 9 7 8 – 9 8 3
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Scheme 3
Scheme 4
formation of olate 6a could be rationalized by the hydrolysis of
the intermediate Michael adduct 9, whose exocyclic amino
group acts as a good leaving group.
The reaction of 4a with benzyne gave the 1,3-diphenyl-5-(2-
anilinophenyl)tetrazolium salt 10, where benzyne inserted into
the exocyclic C–N bond of 4a, probably via the course shown
in Scheme 5. The attempted reactions of 4a with dimethyl
azodicarboxylate and tetracyanoethylene did not proceed.
(c) Reactions of 1,3-diphenyltetrazolium-5-amide (11)
The reaction of amide 11 with DMAD gave the Michael
addition product 12 as a mixture of two geometrical isomers
(Scheme 6). The isomers could be separated readily by column
chromatography; however, the assignments could not be made.
Benzyne inserted into the exocyclic N–H bond of 11 to give
anilide 4a. Tetracyanoethylene similarly reacted with 11 to
give tricyanovinylamide 13, via the Michael addition followed
by the elimination of HCN. The reaction with tetrazine 14
proceeded smoothly to give the ring-opened product 15 as a
mixture of geometrical isomers in the ratio of 59 : 29 : 12.
(d) Reactions of nitrogen-bridged tetrazolium mesoionic
compounds 16–18
The nitrogen-bridged bis(tetrazolium) compounds 16–18 are
another series of nitrogen-rich mesoionic heterocycles. The
reactions of these compounds with electron-deficient alkenes
and alkynes were also examined. The tripolar mesoionic
compound 16 reacted neither with DMAD nor with tetra-
cyanoethylene, probably owing to the steric crowding around
the exocyclic active site. In contrast, compound 17 reacted
smoothly with DMAD to give 19 (21%) and olate 6a (21%)
Scheme 5
(Scheme 7). A small amount of 12 (2%) was also isolated. The
compound 19 was alternatively prepared from 20 and DMAD
in high yield (91%). Similarly, the reaction of 17 with dibenzoyl-
acetylene gave 21 (19%) and olate 6a (46%). Triazenide 18 did
O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 9 7 8 – 9 8 3
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compounds show unique reaction behavior towards electro-
philes and have proved to be useful building blocks for the
synthesis of new nitrogen heterocycles.
Experimental
General
Melting points were determined with a hot-stage apparatus and
are uncorrected. Infrared spectra were taken for potassium
1
bromide discs with a JASCO A-102 instrument. H and 13C
NMR spectra were run with a Varian Gemini 200 instrument
(200 and 50 MHz, respectively) and referenced using either the
residual non-deuterated solvent or tetramethylsilane. Electronic
spectra were measured on a Hitachi U-3500 spectrophotometer.
Mass spectra were measured with a Hitachi M-2000S spectro-
meter (EI, 70 eV). Elemental analyses were performed with
a Perkin Elmer 2400 II CHNS/O or at the Elemental Analysis
Centre of Kyoto University. Column chromatography was
carried out on silica gel (Nacalai Tesque, silica gel 60
7734.5000) or on 3-aminopropylsilane-modified silica gel
(Fuji Silysia Chemical, NH-DM 1020, 100–200 mesh). For
TLC, Merck Silica gel 60 F254 Plate or Fuji Silysia Chemical
NH was used. H218O (95–97%) was purchased from Cambridge
Isotope Laboratories, Inc. CH2Cl2, toluene and MeCN were
dried with CaH2 and distilled before use.
Scheme 6
not react with DMAD, probably owing to the poor nucleo-
philicity, because the negative charge in 18 is delocalized over
the three bridging nitrogen atoms.
Reaction of 2-phenyl-1H-tetrazolo[1,5-a]benzimidazolium inner
salt (1) with DMAD
Conclusion
The reactions of heteropentalene mesomeric betaine 1 and
a variety of nitrogen-rich mesoionic tetrazolium-5-amides 4,
11 and 16–18 with electron-deficient unsaturated compounds
have been studied. The reactions are initiated by the nucleo-
philic attack of the electron-rich amide nitrogen. The resulting
zwitterionic intermediates undergo further reactions to give
a variety of products, depending on the substituent on the exo-
cyclic nitrogen-atom and the electrophiles. The novel hetero-
cyclic systems, tetrazolo[4,5-a][1,7]benzodiazonine inner salt 2
and pyrazolo[3,4-b]pyridine 5, have been synthesized from 1
and 4, respectively, and fully characterized by crystallography.
The present work demonstrates that the tetrazole mesomeric
A mixture of 13 (50 mg, 0.21 mmol) and DMAD (1.0 mL,
8.3 mmol) was stirred under argon for 5 h. The reaction mixture
was subjected to column chromatographic purification (NH-
DM 1020/CH2Cl2, Rf = 0.50) to give a red solid of 4,5,6,7-tetra-
kis(methoxycarbonyl)-2-phenyl-4H-tetrazolo[4,5-a][1,7]benzo-
diazonin-2-ium-4-ide (2) (85 mg, 78%). Analytical samples were
obtained after recrystallization from ethanol: mp 144–146 ЊC;
1
IR (KBr) cmϪ1 1730, 1700, 1470, 1428, 1220, 1188, 764; H
NMR (CDCl3) δ 3.55 (s, 3H), 3.66 (s, 3H), 3.73 (s, 3H), 3.88
(s, 3H), 7.00 (d, J = 8.8 Hz, 1H), 7.35–7.70 (m, 6H), 8.15 (d,
J = 8.4 Hz, 2H); 13C NMR (CDCl3) δ 51.0 (Me), 51.7 (Me), 52.4
(Me), 53.4 (CϪ), 53.6 (Me), 113.6, 120.7 (CH), 120.8 (o-C of
Scheme 7
O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 9 7 8 – 9 8 3
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Ph), 123.3, 126.9 (CH), 127.4 (CH), 129.9 (m-C of Ph), 132.6
(CH), 132.8 (CH), 135.1, 145.3, 147.8, 161.8, 162.5, 163.4,
166.1, 167.7, 168.3; MS m/z 492 (31%), 491 (100, Mϩ Ϫ N2), 460
(34), 400 (30), 338 (31), 324 (49); HRMS m/z (Mϩ Ϫ N2) calcd
491.1326, obsd 491.1320; UV/Vis (MeCN) λmax (log ε)/nm 283.0
(4.27), 386.0 (4.08). Anal. Calcd for C25H21N5O8ؒ1/2 C2H5OH
(542.6): C, 57.55; H, 4.47; N,12.91. Found: C, 57.49; H, 4.56;
N, 12.88%.
Trimethyl 7-(4-ethylphenyl)-3-oxo-2-phenyl-3,7-dihydro-2H-
pyrazolo[3,4-b]pyridine-4,5,6-tricarboxylate (5b)
Purple needles, mp 170–173 ЊC; IR (KBr) cmϪ1 1750, 1722,
1678, 1640, 1434, 1306, 1220; 1H NMR (CDCl3) δ 1.32 (t,
J = 7.5 Hz, 3H), 2.78 (q, J = 7.5 Hz, 2H), 3.62 (s, 3H), 3.86
(s, 3H), 4.12 (s, 3H), 7.13 (t, J = 7.4 Hz, 1H), 7.28–7.43 (m, 6H),
7.96 (d, J = 7.7 Hz, 2H); 13C NMR (CDCl3) δ 15.0 (Me), 28.5
(CH2), 53.1 (Me), 53.3 (2 × Me), 119.8 (o-C of Ar), 125.4 (CH),
127.4 (o-C of Ar), 128.8 (m-C of Ar), 129.3 (m-C of Ar), 132.5,
138.9, 145.0, 147.6, 148.9, 157.4, 161.1, 162.7, 163.9 (three
quaternary carbons were not observed); MS m/z 491 (6%), 490
(30), 489 (100, Mϩ); UV/Vis (MeCN) λmax (log ε)/nm 251.0
(4.42), 310.0 (4.50), 356.0 (sh, 3.54), 496.5 (3.39). Anal. Calcd
for C26H23N3O7ؒ1/2CH2Cl2: C, 59.83; H, 4.55; N, 7.90. Found:
C, 59.74; H, 4.42; N, 7.62%.
Reaction of 1 with benzyne
A solution of tetra-n-butylammonium fluoride in THF (1.0 M,
1.0 mL, 1.0 mmol) was added over 5 min to a mixture of 1
(0.10 g, 0.42 mmol) and phenyl[2-(trimethylsilyl)phenyl]-
iodonium triflate 6 (0.42 g, 0.84 mmol) in CH2Cl2 (5 mL) under
reflux, and the mixture was further refluxed for 1 h. The solvent
was removed and the residue was chromatographed on silica gel
(CH2Cl2–MeCN gradient) to give a yellow solid of 3 (58 mg,
42%). Analytical samples were obtained after recrystallization
from a CH2Cl2–hexane mixture: mp 108–110 ЊC; IR (KBr) cmϪ1
3250, 1688, 1596, 1490, 1334, 1314, 1296, 750; 1H NMR
(DMSO-d6) δ 6.91 (t, J = 8.0 Hz, 1H), 7.02 (d, J = 8.0 Hz, 1H),
7.04 (d, J = 8.0 Hz, 2H), 7.24 (t, J = 8.0 Hz, 2H), 7.39 (d,
J = 8.0 Hz, 1H), 7.44 (t, J = 8.0 Hz, 1H), 7.50 (d, J = 8.0 Hz,
1H), 7.67–7.72 (m, 3H), 7.96 (s, 1H), 8.03–8.04 (m, 2H); 13C
NMR (CD3CN) δ 119.4 (o-C of Ph), 120.1 (CH), 121.1 (o-C of
Ph), 122.1 (CH), 122.5 (CH), 124.2, 128.5 (CH), 130.4 (m-C of
Ph), 130.9 (m-C of Ph), 132.1 (CH), 132.5 (CH), 137.8, 140.4,
143.5, 161.2; MS m/z 330 (22%), 329 (93, Mϩ), 168 (100), 167
(78), 77 (19). HRMS m/z (Mϩ) calcd 329.1275, obsd 329.1265;
UV/Vis (MeCN) λmax (log ε)/nm 280.0 (4.34), 316.0 (sh, 3.94),
370.5 (sh, 3.43). Anal. Calcd for C19H15N5O: C, 69.29; H, 4.60;
N, 21.25. Found: C, 69.44; H, 4.42; N, 21.12%.
Reaction of 4a with benzyne
A solution of tetra-n-butylammonium fluoride in THF (1.0 M,
0.46 mL, 0.46 mmol) was added to a mixture of 4a (0.10 g,
0.32 mmol) and phenyl[2-(trimethylsilyl)phenyl]iodonium
triflate (0.19 g, 0.38 mmol) in CH2Cl2 (7.0 mL) under reflux,
and the mixture was stirred at room temperature for 1 h. The
solvent was removed and the residue was separated by column
chromatography (silica gel/CH2Cl2, then NH-DM 1020/CH2Cl2
: hexane = 1 : 2) to give crude 10 (48 mg) and the starting
compound 4a (40 mg, 40% recovery). The crude 10 was
recrystallized from ethanol to give pure compound (32 mg,
26%); yellow solid; mp 193–195 ЊC; IR (KBr) cmϪ1 3320, 1596,
1496, 1284, 1254, 1158, 1032; 1H NMR (CDCl3) δ 6.73 (d,
2H, J = 7.5 Hz), 6.84 (t, 1H, J = 7.5 Hz), 6.99–7.10 (m, 3H),
7.34–7.51 (m, 4H), 7.56–7.73 (m, 7H), 8.33 (d, 2H, J = 7.8 Hz);
13C NMR (CDCl3) δ 119.5 (CH), 119.7 (o-C of Ph), 122.3
(CH), 122.5 (o-C of Ph), 123.3 (CH), 125.0 (o-C of Ph), 130.1
(m-C of Ph), 131.3 (m-C of Ph), 131.8 (m-C of Ph), 133.3 (CH),
133.7 (CH), 134.9 (CH), 135.9 (CH), 136.1, 141.9, 144.6, 159.6
(two quaternary carbons were not observed); MS m/z 391
(37%), 390 (100, Mϩ), 361 (52), 284 (29), 270 (41), 269 (67), 268
(22), 256 (17), 255 (16), 195 (31), 194 (23), 193 (18), 192 (17),
167 (16), 77 (85); UV/Vis (MeCN) λmax (log ε)/nm 279.5
(4.36), 358.0 (sh, 3.65). Anal. Calcd for C26H20F3N5O3S
(539.49): C, 57.88; H, 3.74; N, 12.98. Found: C, 57.75; H, 3.71;
N, 12.74%.
Reaction of 4a and DMAD
DMAD (1.2 mL, 9.6 mmol) was added to a solution of 4a7
(0.30 g, 0.96 mmol) in acetonitrile (10 mL) and the mixture was
stirred for 30 min. The solvent was removed and the residue
was chromatographed on NH-SiO2 to give the naphthalene
derivative 78 (8 mg, 1%), olate 6a (61 mg, 27%), and the
pyrazolo[3,4-b]pyridine derivative 5a (55 mg, 12%). Analytical
samples of 5a were obtained after recrystallization from a
CH2Cl2–hexane mixture.
Reactions of 11 and 17 with electron-deficient unsaturated
compounds were carried out similarly. The details are given in
the ESI.†
Trimethyl 3-oxo-2,7-diphenyl-3,7-dihydro-2H-pyrazolo[3,4-b]-
pyridine-4,5,6-tricarboxylate (5a)
Purple crystals, mp 210–214 ЊC; IR (KBr) cmϪ1 1748, 1722,
1678, 1640, 1438, 1308, 1222; 1H NMR (CDCl3) δ 3.61 (s, 3H),
3.87 (s, 3H), 4.11 (s, 3H), 7.13 (t, 1H, J = 8.0 Hz), 7.35 (d, 2H,
J = 8.0 Hz), 7.44–7.50 (m, 2H), 7.57–7.63 (m, 3H), 7.95 (d, 2H,
J = 8.0 Hz); 13C NMR (CDCl3) δ 53.1 (Me), 53.5 (2 × Me),
119.5 (o-C of Ph), 125.3 (CH), 127.5 (o-C of Ph), 128.6 (m-C of
Ph), 129.8 (m-C of Ph), 131.0 (CH), 134.6, 138.8, 142.7, 145.0,
148.6, 157.2, 160.8, 162.6, 163.9 (two quaternary carbons were
not observed); MS m/z 462 (29%, Mϩ), 461 (100, Mϩ), 205 (56),
77 (46); HRMS m/z (Mϩ) calcd 461.1222, obsd 461.1253. UV/
Vis (MeCN) λmax (log ε)/nm 248.0 (4.22), 310.5 (4.29), 360.5
(sh, 3.59), 501.5 (3.07). Anal. Calcd for C24H19N3O7ؒ1/2
CH2Cl2: C, 58.39; H, 4.01; N, 8.34. Found: C, 58.60; H, 4.08;
N, 8.31%.
Crystal-structure determination of 2 and 5b‡
Crystal data for 22ؒCH3CH2OH. A crystal grown from
ethanol was used for X-ray crystallography. C52H48N10O17, M =
1085.01, monoclinic, space group P21/n, a = 10.179(1), b =
24.478(2), c = 22.389(7) Å, β = 102.01(2)Њ, V = 5456(1) Å3, Z = 4,
Dc = 1.321 g cmϪ3, F(000) = 2264.00, µ = 1.01 cmϪ1, radiation
MoKα, T = 288 K, 2θ limit = 51.4Њ, 8096 reflections observed,
6464 reflections used (I > 2.00σ(I )), number of variables = 698,
R = 0.092, Rw = 0.142.
Crystal data for (5b)4ؒ(CH2Cl2)2. A crystal grown from
CH2Cl2–hexane was used for X-ray crystallography. C106H96-
Cl4N12O28, M = 2127.80, monoclinic, space group P21/c, a =
20.577(4), b = 23.749(4), c = 21.249(9) Å, β = 100.59(2)Њ, V =
10207.23 Å3, Z = 4, Dc = 1.385 g cmϪ3, F(000) = 4432.00,
µ = 2.01 cmϪ1, radiation MoKα, T = 288 K, 2θ limit = 51.4Њ,
12240 reflections observed, 7212 reflections used (I > 2.00σ(I )),
number of variables = 1350, R = 0.112, Rw = 0.174.
Reaction of 4b with DMAD
A solid of 4b (0.30 g, 0.85 mmol) was placed in a flask and
cooled to Ϫ30 ЊC. DMAD (1.0 mL, 8.6 mmol) was added
slowly and the mixture was stirred at Ϫ1 ЊC for 14 h. The
mixture was subjected to column chromatography (SiO2 and
then NH-DM 1020) to give 89 (5 mg, 2%), olate 6b (90 mg,
43%), and 5b (21 mg, 5%). Analytical samples of 5b were
obtained after recrystallization from a CH2Cl2–hexane mixture.
‡ CCDC reference numbers 197992 and 197993.
O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 9 7 8 – 9 8 3
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2965–3011; (e) A. M. Simas, J. Miller and P. F. de Athayde Filho,
Acknowledgements
Can. J. Chem., 1998, 76, 869–872 and references cited therein.
3 K. T. Potts, in 1,3-Dipolar Cycloaddition Chemistry, ed. A. Padwa,
Wiley-Interscience, New York, 1984 . For a recent example, see;
A. Padwa, T. M. Heidelbaugh and J. T. Kuethe, J. Org. Chem., 2000,
65, 2368–2378.
4 S. Araki, H. Hattori, N. Shimizu, K. Ogawa, H. Yamamura and
M. Kawai, J. Heterocycl. Chem., 1999, 36, 863–867.
5 A. Maquestiau and J. J. Vanden Eynde, Bull. Soc. Chim. Belg., 1987,
96, 793–796 . See also: A. W. Erian, V. F. Araki, S. I. Aziz and S. M.
Sherif, Monatsh. Chem., 1999, 130, 661–669.
We thank Professor J. J. Vanden Eynde of Universite de
Mons-Hainaut for his generosity in sending samples of
some heterocyclic compounds. We also thank Professor
Hideki Masuda, Nagoya Institute of Technology, for X-ray
crystallography, and Ms Kaori Yamamoto for elemental
analyses.
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