Unusual methylene transfer in reactions of Simmons-Smith reagent with 1,3-diazabuta-1,3-dienes: Synthesis of functionalised imidazole derivatives

Article abstract of DOI:10.1016/S0040-4020(02)00127-8

The reactions of Simmons-Smith reagent with 1-aryl-2-phenyl-4-methylthio-4-secondary amino 1,3-diazabuta-1,3-dienes 1 underwent an unusual 1,4-methylene transfer resulting in the formation of 1-aryl-2-phenyl-4-secondary amino imidazoles 4. Whereas, its re

Full text of DOI:10.1016/S0040-4020(02)00127-8

TETRAHEDRON
Pergamon
Tetrahedron 58 =2002) 2899±2904
Unusual methylene transfer in reactions of Simmons±Smith
reagent with 1,3-diazabuta-1,3-dienes: synthesis of functionalised
imidazole derivatives
S. Jayakumar and Mohinder P. Mahajanp
Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, Punjab 143 005, India
Received 26 October 2001; revised 2 January 2002; accepted 31 January 2002
AbstractÐThe reactions of Simmons±Smith reagent with 1-aryl-2-phenyl-4-methylthio-4-secondary amino 1,3-diazabuta-1,3-dienes 1
underwent an unusual 1,4-methylene transfer resulting in the formation of 1-aryl-2-phenyl-4-secondary amino imidazoles 4. Whereas, its
reactions with 1-aryl-2-phenyl-4-secondary amino-1,3-diazabuta-1,3-dienes 8 underwent an initial 1,2-methylene transfer leading to an
aziridine intermediate which rearranges to 1-aryl-4-phenyl-imidazoles 11. q 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction
the attention of chemists and is an almost neglected area.
The reagent reportedly fails to react with aldimines bearing
aryl/alkyl substituents and to our knowledge the only known
addition of the reagent to an imine involves methylene
transfer from the reagent to C-ethoxycarbonyl-N-t-butyl
imine, yielding aziridine.9 In continuation of our efforts to
develop synthetic strategies around 1,3-diazabuta-1,3-
dienes, in a recent communication, we have reported10 an
unusual 1,4-methylene transfer in their reactions with the
Simmons±Smith reagent. We report herein a detailed
account of such methylene transfer reactions of the reagent
with 1,3-diazabuta-1,3-dienes.
The discovery and development of new chemical reactions
is a major focus of research activity in organic chemistry.
The chemical synthesis of molecules provided by nature has
traditionally been the arena in which the utilities of new
reactions are critically evaluated.1 A vast array of new
methods and creative strategies has arisen from this activity.
The development of new strategies and reactions are stimu-
lated by efforts to rationally design synthesis of natural and
non-natural compounds with interesting molecular architec-
tures.1 Reactions, which form multiple bonds, rings, and/or
stereocenters are particularly important tools for the
ef®cient assembly of complex molecular structures.2
2. Results and discussion
Since the discovery of the Simmons±Smith reagent3 it has
been widely used in the cyclopropanation of a variety of
alkenes. In the case of ole®ns bearing heteroatomic sub-
stituents, the hetero atom reportedly co-ordinates with the
reagent thereby enhancing its proximity to the p-bond, and
in¯uencing the stereochemical outcome of the reaction.4
Accordingly, rate acceleration and stereo-directing effects
of allylic alcohols and ethers were interpreted on the basis of
complexation induced proximity effects.5,6 The preferential
1,2-methylene transfer mode has also been observed in
reactions of the Simmon±Smith reagents with 1,3-dienes.7
The fascinating stereospeci®c methylene transfer process
involved in these reactions has also attracted the attention
of theoretical chemists.8 However the reactions of this
reagent with imines and azadienes appears to have evaded
The treatment of 1-aryl-2-phenyl-4-secondary amino-4-
methylthio-1,3-diazabuta-1,3-diene 2 with the Simmons±
Smith reagent, generated from diiodomethane and zinc±
copper couple, in an ethereal solution gave good yields of
1-aryl-2-phenyl-4-secondary amino imidazoles 4. The
products were characterised on the basis of analytical data
and spectral evidences. The detailed spectral features of
these imidazoles are discussed in Section 4, however; only
the salient features are presented here. For example, the
imidazole 4a analysed for C17H17N3 and its mass spectrum
1
exhibited a molecular ion peak at m/z 263. Its H NMR
spectrum exhibited singlets at d 2.49 =6H) for the dimethyl
amino group and at d 6.69 =1H) for the C5-H in addition to
the aromatic protons. The assigned structure was further
supported by the 13C NMR chemical shifts. The resonance
at d 44.32 attest to the presence of dimethylamino group.
The C-5 resonance at d 114.67 also supports the assigned
structure. Multi-functionalised imidazoles so obtained are
of special interest because of the wide range of biological
Keywords: Simmons±Smith reagent; imidazole derivatives; 1,4-addition;
proximity effect; 1,3-diazabutadienes.
p
Corresponding author. Fax: 191-258819-20;
e-mail: mohinderpmahajan@angel®re.com
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020=02)00127-8

2900
S. Jayakumar, M. P. Mahajan / Tetrahedron 58 .2002) 2899±2904
Scheme 1.
properties ascribed to such systems and consequently the
search for alternative, convenient routes to their synthesis
continues to be of great interest.
ion peak at m/z 263=M 1, 100%), and an intense peak at
m/z 180 =59%) corresponding to the fragment Ph-CvN-
Php1 which most likely can arise only from imidazole 4a
and not from imidazole 7a. These results assume further
signi®cance in light of the reported reactions of the
Simmons±Smith reagent with a-oxoketene dithioacetals
leading to thiophene derivatives via intramolecular aldol
type reaction of initially formed sulfur ylides.11 The obvia-
tion of such a possibility in present studies, despite the fact
that sulfur ylide formation is reported to be much faster than
carbene insertion,12 lends further credence to the proposed
double coordination of the reagent with the N1 and sulfur of
the methylthio of 1,3-diazabuta-1,3-diene 1. These observa-
tions further highlight the signi®cance of the role the
heteroatomic substitutents play in directing the methylene
transfer from the Simmons±Smith reagent.
The plausible mechanism for the formation of imidazoles 4
is depicted in Scheme 1. In this scheme it is assumed that the
Simmons±Smith reagent co-ordinates with the sulfur of the
methylthio group, with simultaneous interaction of methyl-
ene with N-1 and C-4 of 1,3-diazabuta-1,3-dienes, leads to
an intermediate 2. The intermediate 2 on methylene transfer
forms to another intermediate 3 which on elimination of
methylmercaptan ®nally yields imidazole 4. It is also likely
that an initial [112] addition of the Simmons±Smith
reagent across the carbon±nitrogen =1,2) double bond of
the 1,3-diazabuta-1,3-diene may lead initially to an aziridine
intermediate 5, which rearranges to another intermediate 6
and then undergoes an elimination of methylmercaptan to
1
yield imidazole 7. On the basis of available analytical, H
In order to have a better understanding of this mechanisti-
cally fascinating and synthetically valuable route to sub-
stituted imidazoles, we have also examined the reactions
of 1-aryl-2-phenyl-4-secondary amino-1,3-diazabuta-1,3-
dienes 8 with the Simmons±Smith reagent. Thus, the treat-
ment of the Simmons±Smith reagent with 1,3-diazabuta-
1,3-dienes 8 resulted in the isolation of products which
and 13C NMR spectral data it is dif®cult to discriminate this
isomeric imidazole structure in favour of structure 5.
However, the structure 4 for the formed imidazoles is
favoured over the alternative structure 7, on the basis of
mass spectral fragmentation data. For example, the
compound 4a, showed in its mass spectrum a molecular

S. Jayakumar, M. P. Mahajan / Tetrahedron 58 .2002) 2899±2904
2901
Scheme 2.
were characterised as imidazoles 11 on the basis of
analytical data and spectral evidences. The detailed spectral
features of these imidazoles are reported in Section 4, while
the salient features are presented here. For example, the
imidazole 11b analysed for C16H14N2 and its mass spectrum
exhibited a molecular ion peak at m/z: 23 4 =M). Its H
NMR spectrum exhibited singlet at d 2.33 =3H) for the
aromatic substituted methyl group and two singlets at d
7.03=1H) and d 7.05 =1H) in addition to aromatic protons.
The assigned structure was further corroborated by the 13C
NMR and 13C DEPT =135) chemical shifts. The resonance at
d 20.81 attest to the presence of aromatic substituted methyl
group and the C-5 resonance at d 120.41 and C-2 resonance
at d 129.72 further supports the assigned structure.
these reactions may result in imidazoles 13 via elimination
of dimethyl amine from initially formed imidazoline 12 as
an intermediate. The formation of 12 may involve either a
1,4-methylene transfer from the Simmons±Smith reagent to
1,3-diazabuta-1,3-diene 8 =Path II) or a rearrangement
involving the scission of the carbon±carbon single bond
of aziridine =Path III). However, the structure 11 for the
formed imidazoles was unequivocally decided on the basis
of 1H NMR spectra, which exhibited singlets for the vinylic
protons instead of the doublets expected for structure 13.
The variation in the reaction pathways followed in reactions
of 1,3-diazabuta-1,3-dienes 1 and 8 with the Simmons±
Smith reagent may be attributed to the difference in sub-
stituents at C-4 of these 1,3-diazabuta-1,3-dienes. The
presence of a strongly coordinating methylthio group in
1,3-diazabuta-1,3-diene 1 may result in a hetero-atom
induced proximity effect favourable for 1,4-addition.
1
1
The plausible mechanism for the formation of imidazoles 11
is depicted in Scheme 2. In this scheme it is assumed that the
Simmons±Smith reagent undergoes an initial 1,2-methylene
transfer to yield aziridine intermediate 9 which undergoes
dimethyl amino group assisted aziridine ring opening and its
expansion to form an imidazole intermediate 10 which
®nally isomerises to imidazole 11. It is also likely that
Surprisingly, the Simmons±Smith reagent failed to react
with 1-azadiene under similar experimental conditions and
may possibly be ascribed to the absence of any polar donat-
ing/co-ordinating group at C-4 and lower nucleophilicity of

2902
S. Jayakumar, M. P. Mahajan / Tetrahedron 58 .2002) 2899±2904
the terminal nitrogen of such azadienes. This gives further
credence to the requirement of suitably placed sulfur or
nitrogen containing functional groups in azadienes for the
realisation of 1,4 or 1,2 addition of the Simmons±Smith
reagent.
solution of 1,3-diazabuta-1,3-diene 1 =10 mmol) in dry THF
=25 ml) was added slowly and the reaction mixture re¯uxed
with stirring for a further period of 3±4 h. After completion
of the reaction =TLC), solvent was removed under reduced
pressure and the residue treated with water =100 ml) and
chloroform =75 ml). The reaction mixture was ®ltered and
the residue washed with chloroform =30 ml) and the
combined organic extract was washed with water
=2£50 ml), dried over anhydrous sodium sulfate and evapo-
rated to give crude product which was puri®ed by column
chromatography over silica gel using a mixture of ethyl
acetate and hexane =10:1) as eluent.
3. Conclusion
The reactions of 1-aryl-2-phenyl-4-secondary amino-4-thio-
methyl-1,3-diazabuta-1,3-dienes 1 with the reagent under-
went an unusual 1,4-methylene transfer to yield 1-aryl-2-
phenyl-4-secondary amino imidazoles 4. Whereas, the
reactions of 1-aryl-2-phenyl-4-dimethyl amino-1,3-diaza-
buta-1,3-dienes 8 with the reagent underwent regioselective
1,2 additions followed by rearrangement to yield 1-aryl-4-
phenyl-imidazoles 11. These investigations have shown that
the hetero atom present at C-4 of 1,3-diazabuta-1,3-dienes
facilitates the methylene transfer through complexation
with the reagent.
4.3.1. 1,2-Diphenyl-4-N,N-dimethylamino imidazole 4a.
Yield: 75%; mp 134±1368C; Anal. Calcd for C17H17N3: C,
77.52; H, 6.51; N, 15.96. Found: C, 77.48; H, 6.53; N,
15.99%; IR =KBr) nmax: 1597, 1556, 1514, 1466, 1406,
1363 cm21
;
dH =200 MHz, CDCl3): 2.49 {6H, s,
=NCH3)2}, 6.69 =1H, s, C5-H), 7.15±7.27 =7H, m, ArHs),
7.36±7.42 =3H, m, ArHs); dC =50.4 MHz, CDCl3): 44.32
{N=CH3)2), 114.67, 127.83, 127.99, 128.13, 128.55,
129.29, 137.03, 143.14, 145.53; m/z: 264 =M111, 20%),
263=M 1, 100%), 248 =17%), 180 =58%), 118 =37%), 116
=12%), 89 =18%), 77 =63%).
4. Experimental
4.1. General
4.3.2. 1-0p-Tolyl)-2-phenyl-4-N,N-dimethylamino imida-
zole 4b. Yield: 63%; mp 148±1498C; Anal. Calcd for
C18H19N3: C, 77.95; H, 6.90; N, 15.15. Found: C, 77.97;
H, 6.98; N, 15.05%; IR =KBr) nmax: 1597, 1556, 1514,
1466, 1406, 1363 cm21; dH =200 MHz, CDCl3): 2.39 =3H,
s, ±CH3), 2.68 {6H, s, N=CH3)2}, 6.71 =1H, s, C5-H), 7.08
=2H, d, Jˆ8.1 Hz, ArH), 7.16 =2H, d, Jˆ8.1 Hz, ArH),
7.21±7.28 =5H, m, ArH); dC =50.4 MHz, CDCl3): 21.19
=±CH3), 44.45, {N=CH3)2, 114.72, 127.33, 127.50, 127.76,
128.33, 129.49, 130.86, 133.92, 137.69, 142.62 and 145.53;
m/z: 278 =M111, 21%), 277 =M1, 72%).
Melting points were determined by open capillary method
using Veego Precision Digital Melting Point apparatus
=MP-D) and are uncorrected. IR spectra were recorded on
1
a Shimadzu D-8001 spectrophotometer. H NMR spectra
were recorded in deuterochloroform with Brucker AC-E
200 =200 MHz) spectrometer using TMS as internal
standard. Chemical shift values are expressed as d =ppm)
down®eld from TMS and J values are in Hz. Splitting
patterns are indicated as s: singlet, d: doublet, t: triplet, m:
multiplet, q: quartet and br: broad peak. 13C NMR spectra
were also recorded on a Brucker AC-200E =50.4 MHz)
spectrometrer in deuterochloroform using TMS as internal
standard. Mass spectra were recorded on Shimadzu GCMS-
QP-2000 mass spectrometer. Elemental analyses were
performed on Heraus CHN-O-Rapid Elemental Analyser.
Column chromatography was performed on a silica gel
=60±120) or Harrison Research Chromatotron using 2 mm
plates =Silica gel 60 PF254). THF/Diethyl ether were dried
over sodiumbenzophenone ketyl and distilled under
nitrogen. All manipulations were conducted over a puri®ed
nitrogen atmosphere =BASF-Catalyst-R3-11) by use of
standard Schlenck techniques.
4.3.3. 1,2-Diphenyl-4-piperidino imidazole 4c. Yield:
72%; mp 154±1568C; Anal. Calcd for C20H21N3: C, 79.17;
H, 6.98; N, 13.85. Found: C, 79.23; H, 6.95; N, 13.82%; IR
=KBr) nmax: 1597, 1559, 1520 1406 cm21; dH =200 MHz,
CDCl3): 1.44 =6H, br, ±CH2±CH2±CH2±), 2.72 =4H, br,
±CH2±N±CH2±), 6.66 =1H, s, C5-H), 7.14±7.42 =10H, m,
ArHs); dC =50.4 MHz, CDCl3): 21.06 =±CH2±), 25.64
=±CH2±), 53.03 =±CH2±N±CH2), 114.67, 127.83, 127.99,
128.13, 128.55, 129.29, 137.03, 143.14, and 145.53; m/z:
303 =M1).
4.3.4. 1-0p-Tolyl)-2-phenyl-4-piperidino imidazole 4d.
Yield: 65%; mp 164±1658C; Anal. Calcd for C21H23N3: C,
79.46; H, 7.30; N, 13.24. Found: C, 79.45; H, 7.34; N,
13.21%; IR =KBr) nmax: 1597, 1556, 1514, 1466, 1406,
4.2. Starting materials
1-Aryl-2-phenyl-4-thiomethyl-4-secondary amino-1,3-diaza-
buta-1,3-dienes 1,13 1-Aryl-2-phenyl-4-N,N-dimethyl-
amino-1,3-diazabuta-1,3-dienes 8,13 were prepared by
reported methods.
1364 cm21; dH =200 MHz, CDCl3): 1.43=6H, br, ±CH ±
2
CH2±CH2±), 2.39 =3H, s, ±CH3), 2.71 =4H, br, ±CH2±N±
CH2±), 6.72 =1H, s, C5-H), 7.09 =2H, d, Jˆ8.3Hz, ArH),
7.18 =2H, d, Jˆ8.3Hz, ArH), 7.21±7.29 =5H, m, ArH);
dC =50.4 MHz, CDCl3): 21.09 =±CH2±), 23.76 =±CH2±),
25.64 =±CH3), 53.03 =±CH2±N±CH2±), 114.67 =C5),
127.83, 127.99, 128.13, 128.55, 129.29, 137.03, 143.14,
145.53; m/z: 318 =M111, 27%), 317 =M1, 100%), 207 =9%).
4.3. Reactions of Simmons±Smith reagent with 1,3-
diazabuta-1,3-dienes 1
To a well stirred solution of zinc±copper couple =10 mmol)
in dry ether =20 ml) under a nitrogen atmosphere a small
crystal of iodine and diiodomethane =25 mmol) were added
and the reaction mixture re¯uxed with striring for 10 min. A
4.3.5. 1-0p-Tolyl)-2-phenyl-4-pyrrolidino imidazole 4e.
Yield: 65%; mp 147±1488C; Anal. Calcd for C20H21N3: C,

S. Jayakumar, M. P. Mahajan / Tetrahedron 58 .2002) 2899±2904
2903
79.17; H, 6.98; N, 13.85. Found: C, 79.20; H, 6.92; N,
13.90%; IR =KBr) nmax: 1597, 1556, 1514, 1466, 1406,
1363 cm21; dH =200 MHz, CDCl3), 1.77 =4H, br, ±CH2±
CH2±), 2.36 =3H, s, ±CH3), 3.08 =4H, br, ±CH2±N±CH2±
), 6.72 =1H, s, C5-H), 7.09 =2H, d, Jˆ8.3Hz, ArH), 7.18
=2H, d, Jˆ8.3Hz, ArH), 7.21±7.29 =5H, m, ArH); dC
=50.4 MHz, CDCl3): 21.09 =±CH2±CH2±), 25.64 =2£±
CH2±), 48.7 =±CH2±N±CH2±), 114.67 =C-5), 127.83,
127.99, 128.13, 128.55, 129.29, 137.03, 143.14, 145.53;
m/z: 304 =M111, 27%), 303 =M1, 73%).
4.3.11. 1-0o-Tolyl)-4-phenyl-imidazole 11d. Yield: 63%;
mp 87±898C; Anal. Calcd for C16H14N2: C, 82.05; H,
5.98; N, 11.97. Found: 82.09; H, 6.02; N, 11.89%; IR
=KBr) nmax: 1566, 1497, 1466, 1398, 1363 cm21; dH
=200 MHz, CDCl3): 2.01 =3H, s, ±CH3), 6.92 =1H, s,
C5-H), 7.10±7.39 =10 H, m, ArH); dC: 10.3=q, ±CH ),
3
126.5 =d), 127.9 =d), 128.1 =d), 128.6 =d), 129.5 =d), 130.2
=s), 130.9 =s), 137.6 =s), 146.8 =s); m/z: 23 5 =M 11, 15%),
1
234 =M1, 92%), 233 =100%).
4.3.6. 1,2-Diphenyl-4-morpholino imidazole 4f. Yield:
72%: mp 103±1058C; Anal. Calcd for C19H19N3O: C,
74.73; H, 6.27; N, 13.76. Found: C, 74.77; H, 6.30; N,
13.79%; IR =KBr) nmax: 1597, 1556, 1514, 1466, 1406,
1363 cm21; dH =200 MHz, CDCl3): 3.70 =4H, m, ±CH2±
N±CH2±), 3.93 =4H, m, ±CH2±O±CH2±), 6.84 =d,
Jˆ7.5 Hz), 7.03±7.48 {9H, m, consisting in at 7.12 =1H,
s, C5-H) ArH}; m/z: 305 =M1).
Acknowledgements
The authors gratefully acknowledge the ®nancial support by
CSIR, New Delhi for a Senior Research Fellowship to S. J.
and grant No: 01=1590/99/EMR-11).
References
4.3.7. 1-0p-Tolyl)-2-phenyl-4-morpholino imidazole 4g.
Yield: 67%; mp 132±1338C. Anal. Calcd For C20H21N3O:
C, 75.21; H, 6.63; N, 13.16. Found: C, 75.24; H, 6.68; N,
13.20%; IR =KBr) nmax: 1597, 1561, 1516, 1466, 1406,
1331 cm21; dH =200 MHz, CDCl3): 2.25 =3H, s, ±CH3),
3.66 =4H, br, ±CH2±N±CH2±), 3.91 =4H, br, ±CH2±O±
CH2±), 6.72 =2H, d, Jˆ8.2 Hz, ArH), 6.93=2H, d,
Jˆ8.2 Hz, ArH), 7.21±7.45 {10H, m, consisting in at 7.28
=1H, s, C5-H), ArH}; dC =50.4 MHz, CDCl3): 20.66 =±CH3),
42.3=± CH2±N±CH2±), 45.4 =±CH2±O±CH2±), 123.5,
127.8, 129.2, 130.0, 134.2, 136.3, 163.4, 164.0; m/z: 3 19
=M1, 7.5%), 237 =100%), 236 =83%).
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Wiley: New York, 1989. =b) Fleming, I. Selected Organic
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2. Nicolaou, K. C.; Vourloumis, D.; Winssinger, N.; Baran, P. S.
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therein.
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Hoiness, C. M. Org. React. 1973, 20, 1. =c) Corey, E. J.; Reid,
G. J.; Myer, A. G.; Hahl, R. W. J. Am. Chem. Soc. 1987, 109,
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propanes. Comprehensive Organic Synthesis; Trost, B. M.,
Ed.; Pergamon: Oxford, 1991; Vol. 4, pp 968±975 and
references therein.
4.3.8. 1,4-Diphenyl-imidazole 11a. Yield: 57%; mp 132±
1338C; Anal. Calcd for. C15H12N2: C, 81.79; H, 5.49; N,
12.72. Found: C, 81.82; H, 5.52; N, 12.67%; IR =KBr)
n
max: 1566, 1497, 1467, 1396, 1363 cm21; dH =200 MHz,
CDCl3): 6.99±7.37 {11H, m, consisting in at 7.02 =1H, 9 s,
C3-H) and 7.03 =1H, s, C5-H) ArH)}; m/z: 221 =M111,
12%), 220 =M1,72%).
4. Hoffman, R. W. Chem. Rev. 1989, 89, 1841 and references
therein.
4.3.9. 1-0p-Tolyl)-4-phenyl-imidazole 11b. Yield: 63%;
mp 106±1078C; Anal. Calcd for C16H14N2: C, 82.05; H,
5.98; N, 11.97. Found: 82.06; H, 6.05; N, 11.89%; IR
5. =a) Johnson, C. R.; Barbachard, M. R. J. Am. Chem. Soc. 1982,
104, 4290. =b) Neef, G.; Cleve, G.; Ottow, E.; Seeger, A.;
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=KBr) nmax
: 1565, 1496, 1464, 1410, 1307%; dH
=200 MHz, CDCl3): 2.33 =3H, s, ±CH3), 6.97±7.31{10H,
m, consisting in at 7.04 =1H, s, C3-H) and 7.07 =1H, s,
C5-H) ArH}; dC: 20.8 =q, ±CH3), 122.6 =d), 125.3=d),
127.8 =d), 128.0 =d), 128.3=d), 128.4 =d), 129.8 =d), 129.9
6. =a) Beak, P.; Meyers, A. I. Acc. Chem. Res. 1986, 19, 356.
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1
=s), 135.7 =s), 137.7 =s), 146.1 =s); m/z: 23 5 =M 11, 17%),
234 =M1, 100%), 233 =94%).
9. Baret, P.; Buffet, H.; Pierre, H.-L. Bull. Soc. Chim. Fr. 1972,
985.
4.3.10. 1,4-Diphenyl-2-methyl imidazole 11c. Yield: 58%;
mp 67±688C; Anal. Calcd for C16H14N2: C, 82.02; H,
6.02; N, 11.96. Found: 82.05; H, 6.06; N, 11.89%; IR
=KBr) nmax: 1568, 1496, 1464, 1410, 1307 cm21; dH
=200 MHz, CDCl3): 1.93=H3, s, ±CH 3), 6.98 =1H, s,
C2-H), 7.19 {10H, m, consisting in at 7.22 =1H, s, C5-H)
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3
127.3 =d), 127.9 =d), 128.8 =d), 128.9 =d), 130.4 =s), 131.0
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1
17%), 234 =M1, 100%), 233 =31%), 219 =36%), 206
=41%).

2904
S. Jayakumar, M. P. Mahajan / Tetrahedron 58 .2002) 2899±2904
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