Reaction of nitrile ylides with isatins and o-benzoquinones: Formation of novel spirooxazoline derivatives

Article abstract of DOI:10.1016/S0040-4020(02)00182-5

Nitrile ylide generated by the base catalysed reaction of imidoyl chlorides underwent dipolar cycloaddition with isatins, phenanthrenequinone and acenaphthenequinone to afford novel spirooxazoline derivatives.

Full text of DOI:10.1016/S0040-4020(02)00182-5

TETRAHEDRON
Pergamon
Tetrahedron 58 2002) 3003±3007
Reaction of nitrile ylides with isatins and o-benzoquinones:
formation of novel spirooxazoline derivatives
Vijay Nair,a,p D. Sethumadhavan,a Smitha M. Nair,a S. Vijia and Nigam P. Rathb
aOrganic Chemistry Division, Regional Research Laboratory ꢀCSIR), Trivandrum 695019, India
bDepartment of Chemistry, University of Missouri, St. Louis, MO 63121-4499, USA
This paper is dedicated to the memory of Professor Josef Gus) Fried who passed away on 7 August 2001
Received 25 June 2001; accepted 21 February 2002
AbstractÐNitrile ylide generated by the base catalysed reaction of imidoyl chlorides underwent dipolar cycloaddition with isatins,
phenanthrenequinone and acenaphthenequinone to afford novel spirooxazoline derivatives. q 2002 Published by Elsevier Science Ltd.
The monumental work of Huisgen has established 1,3-
dipolar cycloaddition reaction as the most powerful method-
ology for the construction of ®ve membered heterocycles.1
In the context of our general interest in the cycloaddition
chemistry of 1,2-dicarbonyl compounds2 we have shown
that nitrile oxides and carbonyl ylides undergo facile dipolar
cycloaddition to o-quinones.3,4 Very recently we have
observed that carbonyl ylides react readily with isatins to
afford novel spirooxindole derivatives;5 isatin and its
derivatives have interesting biological activities and have
been widely used as precursors of many natural products.6
Scheme 1.
In continuation of these studies it was of interest to explore
the reaction of nitrile ylides with isatins and other 1,2-
yield. As expected, the [213] addition occurred across the
more electrophilic ketonic carbonyl Scheme 1).
dicarbonyl compounds. Although nitrile ylides have
been known to react with a variety of dipolarophiles7±14
including carbonyl compounds such as aldehydes and
1,4-benzoquinones yielding oxazoline derivatives, there
has been no report on their reaction with 1,2-dicarbonyl
compounds such as isatins or 1,2-quinones. Against this
background, we have explored the reactivity of nitrile
ylides towards isatins, acenaphthenequinone and
phenanthrenequinone. Our results revealing the facile
formation of novel spirooxazoline derivatives are
presented here.
The product was puri®ed by chromatography on a silica gel
column, and characterized by spectroscopic analysis. The
1
IR spectrum of 6 showed a band at 1731 cm21. In the H
NMR spectrum, the benzylic and methyl protons resonated
as singlets at d 5.79 and 2.91, respectively. In the 13C NMR
spectrum of 6, the amide carbonyl resonated at d 171.45
whereas the spirocarbon was discernible at d 87.01. The
characteristic imine carbon of the oxazoline ring showed a
signal at d 165.17. These assignments were con®rmed by
DEPT-135 NMR analysis. In the DEPT-135 NMR spectrum
of 6, a peak at d 79.29 for the benzylic carbon was positive
and the spirocarbon signal at d 87.01 disappeared. Finally
the structure assigned was con®rmed unequivocally by
single crystal X-ray analysis Fig. 1).16
Our studies were initiated with the reaction of nitrile ylide 3,
generated by the base catalysed reaction of 4-nitro-N-benzyl
benzimidoyl chloride15 1, and N-methyl isatin 5 in benzene
at room temperature. The reaction proceeded smoothly to
afford an oxazoline fused spirooxindole derivative 6 in 81%
The reaction was extended to three other isatins and also
with nitrile ylide 4 derived from 4-nitro-N-benzyl- 4
methyl) benzimidoyl chloride 2. In all cases, the reaction
proceeded smoothly to afford the spirooxindoles. The
results are summarized in Table 1.
Keywords: nitrile ylides; dipolar cycloaddition; 1,2-diones; spirooxazo-
lines.
Corresponding author. Tel.: 191-471-490-406; fax: 191-471-491-712;
e-mail: gvn@csrrltrd.ren.nic.in
p
0040±4020/02/$ - see front matter q 2002 Published by Elsevier Science Ltd.
PII: S0040-4020 02)00182-5

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V. Nair et al. / Tetrahedron 58 ꢀ2002) 3003±3007
Table 1. [213] Cycloaddition reactions of nitrile ylides 3 and 4 with isatins
Entry Isatin Product Yield %)
1
94
2
83
Figure 1.
1. Reactions of nitrile ylides with 1,2-quinones
3
84
In view of the encouraging results obtained with the nitrile
ylides and isatins it was of interest to study the reaction of
nitrile ylides with acenaphthenequinone and phenanthrene-
quinone. Thus when acenaphthenequinone 17 was allowed
to react with imidoyl chlorides 1 and 2 in presence of
triethylamine, products 18 and 19 were obtained Scheme 2).
4
5
6
70
90
89
The products were puri®ed by chromatography on a silica
gel column, and characterized by spectroscopic analysis and
single crystal X-ray analysis.16 Similarly the reaction of 3
and 4 with phenanthrenequinone 20 was also performed as
described above to afford the corresponding oxazolines 21
and 22 Scheme 3).
In conclusion we have found that nitrile ylides undergo
facile dipolar cycloaddition with isatins and o-benzo-
quinones to afford novel spirooxazoline derivatives.
2. Experimental
Various substituted isatins were prepared according to the
literature procedure.17
2.1. Synthesis of imidoyl chlorides
2.1.1. 4-Nitro-N-benzyl benzimidoyl chloride 1. The
preparation of 4-nitro-N-benzyl bezimidoyl chloride 1 was
carried out according to the known procedure.15
7
63
2.1.2. 4-Nitro-N-benzyl-+4-methyl) benzimidoyl chloride
2. 4-Nitro benzylamine hydrochloride 1 g, 5.3£1023 mol)
was treated with 4-toluoyl chloride 0.819 g,
5.29£1023 mol) in the presence of NaOH 4 mL, 3 M
solution) to afford 4-nitro-N-benzyl- 4-methyl) benzamide
1 g, 70%). This amide on re¯uxing with freshly distilled
thionyl chloride 2.18 g, 0.0185 mol) afforded the title
compound 2 0.630 g, 60%) as a pale yellow solid;
recrystallised from dry cyclohexane. Mp 90±928C;
[Found: C, 62.21; H, 4.47; N, 9.89. C15H13N2O2Cl requires
C, 62.40; H, 4.54; N, 9.70%]; nmax KBr) 1676, 1640, 1599,
1517, 1409, 1347, 1105, 1012, 889, 858, 724 cm21; dH
300 MHz, CDCl3) 8.21 2H, d, Jˆ8.4 Hz, Ar-H), 7.96
2H, d, Jˆ8.0 Hz, Ar-H), 7.61 2H, d, Jˆ8.4 Hz, Ar-H),
7.23 2H, d, Jˆ8.0 Hz, Ar-H), 4.98 2H, s, NCH2), 2.41
3H, s, C6H4CH3); dC 75 MHz, CDCl3) 168.38, 129.30,
129.21, 129.16, 128.35, 128.30, 127.09, 123.88, 123.76,
56.59, 21.50.
2.2. General procedure for the reaction of imidoyl
chlorides with isatins and quinones
2.2.1. +3R,4R0)-1-Methyl-20-+phenyl)-40-+4-nitrophenyl)-
spiro[3H-indole-3, 50+40H)-oxazol]-2+1H)-one 6. The
preparation of the cycloadduct 6 from N-methyl isatin 5

V. Nair et al. / Tetrahedron 58 ꢀ2002) 3003±3007
3005
Scheme 2.
Scheme 3.
and imidoyl chloride 1 is illustrative of the general pro-
cedure for the synthesis of spirooxazolines. N-methyl isatin
0.042 g, 2.60£1024 mol) and imidoylchloride 1 0.10 g,
3.91£1024 mol) were taken up in 2 mL rigorously dried
benzene. To this, triethylamine 0.0434 g, 4.30£1024 mol)
was added and stirred for 3 h under an atmosphere of argon
at room temperature. The orange red reaction mixture
turned colourless. It was then ®ltered through a celite pad
using dichloromethane 50 mL) as solvent. Dichloro-
methane and benzene were removed on a rotary evaporator
and the crude product was subjected to chromatography on a
silica gel column using hexane±ethyl acetate 85:15) as
eluent to afford the title compound 6 0.084 g, 81%) as
colourless crystals; recrystallised from hexane±dichloro-
methane. Mp 221±2238C; [Found: C, 69.16; H, 4.51; N,
10.40. C23H17N3O4 requires C, 69.17; H, 4.29; N, 10.52];
nmax KBr) 1731, 1657, 1607, 1513, 1338, 1088, 1020, 854,
751, 689 cm21. dH 300 MHz, CDCl3) 8.07±8.12 4H, m,
Ar-H), 7.43±7.58 5H, m, Ar-H), 7.22±7.31 3H, m, Ar-H),
6.85 1H, d, Jˆ7.8 Hz, Ar-H), 5.79 1H, s, NCH), 2.91 3H,
s, C6H4CH3); dC 75 MHz, CDCl3) 171.45, 165.17, 147.76,
144.16, 132.29, 131.29, 128.96, 128.54, 127.71, 127.50,
126.63, 124.29, 123.78, 123.33, 108.78, 87.01, 79.29, 26.04.
gˆ908, R indices all data) R1ˆ0.0938, wR2ˆ0.1599,
Ê 3
volume, Zˆ3934.5 2) A , 8, Dcalcˆ1.349 mg m23, absorp-
tion coef®cientˆ0.094 mm21, lˆ0.71073 A, re¯ections
Ê
collected 94917. Sheldrick, G. M., Siemens, Analytical
X-ray Division, Madison, WI, 1995.
2.2.2. +3R,40R)-1-Phenyl-20-+phenyl)-40-+4-nitrophenyl)-
spiro[3H-indole-3,50+40H)-oxazol]-2+1H)-one 10. N-
Phenyl isatin 0.025 g, 0.112 mmol) and imidoyl chloride
1 0.046 g, 0.168 mmol) taken in 2 mL dry benzene was
treated with triethylamine 0.0186 g, 0.184 mmol) under
the standard procedure to afford the title compound 10 as
pale yellow crystals; recrystallised from hexane±dichloro-
methane. Mp 201±2038C; [Found C, 72.74; H, 4.37; N,
8.84. C28H19N3O4 requires C, 72.88; H, 4.15; N, 9.11%];
nmax KBr) 1726, 1651, 1614, 1511, 1346, 1081, 993,
745 cm21; dH 300 MHz, CDCl3) 8.11±8.16 4H, m, Ar-
H), 7.25±7.65 11H, m, Ar-H), 6.90 2H, d, Jˆ7.1 Hz,
Ar-H), 6.82 1H, d, Jˆ7.8 Hz, Ar-H), 5.86 1H, s, NCH);
dC 75 MHz, CDCl3) 170.78, 165.36, 147.81, 144.03,
133.15, 132.34, 131.12, 129.70, 129.01, 128.57, 128.43,
127.87, 127.13, 126.60, 125.88, 124.53, 124.22, 123.39,
110.09, 87.22, 80.17.
Crystal data for 6. C23H17N3O4. M 399.40, orthorhombic,
Ê
2.2.3. +3R,40R)-1-Ethyl-20-+phenyl)-40-+4-nitrophenyl)-
spiro[3H-indole-3,50+40H)-oxazol]-2+1H)-one 11. N-Ethyl
isatin 0.030 g, 0.171 mmol) and imidoyl chloride 1
space group Pbca, unit cell dimensions aˆ16.1255 5) A,
Ê
Ê
aˆ908; bˆ12.2464 4) A, bˆ908; cˆ19.9237 6) A,

3006
V. Nair et al. / Tetrahedron 58 ꢀ2002) 3003±3007
0.046 g, 0.168 mmol) taken in 2 mL dry benzene was
treated with triethylamine 0.0285 g, 0.282 mmol) under
the standard procedure to afford the title compound 11 as
colourless crystals; recrystallised from hexane±ethyl-
acetate. Mp 84±868C; [Found C, 69.74; H, 4.88; N, 9.89.
C24H19N3O4 requires C, 69.72; H, 4.63; N, 10.16%]; nmax
KBr) 1725, 1650, 1613, 1520, 1467, 1341, 1202, 1023, 844,
751, 691 cm21. dH 300 MHz, CDCl3) 8.08±8.11 3H, m,
Ar-H), 7.41±7.58 6H, m, Ar-H), 7.18±7.32 3H, m, Ar-H),
6.85 1H, d, Jˆ7.7 Hz, Ar-H), 5.77 1H, s, NCH), 3.55±3.62
1H, m, NCHHCH3), 3.25±3.32 1H, m, NCHHCH3), 0.87±
0.95 3H, m, NCH2CH3); dC 75 MHz, CDCl3) 171.01,
165.33, 147.75, 144.05, 143.24, 132.28, 131.19, 128.98,
128.54, 127.87, 127.61, 126.66, 124.46, 123.53, 123.24,
108.77, 87.05, 79.57, 34.54, 12.24.
699 cm21. dH 300 MHz, CDCl3) 8.14 2H, d, Jˆ8.4 Hz,
Ar-H), 8.00 2H, Jˆ7.9 Hz, Ar-H), 7.64 1H, d, Jˆ7.1 Hz,
Ar-H), 7.25±7.44 10H, m, Ar-H), 6.90 1H, d, Jˆ7.7 Hz,
Ar-H), 6.82 1H, d, Jˆ7.7 Hz, Ar-H), 5.85 1H, s, NCH),
2.45 3H, s, C6H4CH3). dC 75 MHz, CDCl3) 170.89,
165.52, 147.82, 144.19, 144.05, 142.87, 133.20, 131.08,
129.72, 129.30, 129.02, 128.43, 127.90, 127.29, 125.91,
124.55, 124.22, 123.83, 123.41, 110.09, 87.14, 80.23,
21.77.
2.2.7. +3R,40R)-1-Ethyl-20-+4-methylphenyl)-40-+4-nitro-
phenyl)spiro[3H-indole-3,50+40H)-oxazol]-2+1H)-one 15.
N-Ethyl isatin 0.030 g, 0.171 mmol) and imidoyl chloride
2 0.074 g, 0.257 mmol) taken in 2 mL dry benzene was
treated with triethylamine 0.028 g, 0.282 mmol) under the
standard procedure to afford the title compound 15 as pale
yellow crystals; recrystallised from hexane±ethyl acetate.
Mp 186±1888C; [Found C, 70.48; H, 5.13; N, 9.99.
C25H21N3O4 requires C, 70.25; H, 4.95; N, 9.83%]; nmax
KBr) 1725, 1646, 1606, 1513, 1467, 1208, 1175, 1082,
1009, 830, 744, 685 cm21; dH 300 MHz, CDCl3) 8.09
2H, d, Jˆ8.4 Hz, Ar-H), 7.97 2H, d, Jˆ8.0 Hz, Ar-H),
7.17±7.57 m, 7H, Ar-H), 6.84 1H, d, Jˆ7.7 Hz, Ar-H),
5.75 1H, s, NCH), 3.55±3.62 1H, m, NCHHCH3), 3.24±
3.31 1H, m, NCHHCH3), 2.44 3H, s, C6H4CH3), 0.87±
0.91 3H, m, NCH2CH3). dC 75 MHz, CDCl3): 171.09,
165.45, 147.73, 144.22, 143.22, 142.77, 131.13, 129.25,
128.97, 127.89, 127.74, 124.46, 123.89, 123.51, 123.24,
108.73, 86.95, 79.60, 34.54, 21.75, 12.26.
2.2.4. +3R,40R)-1-Benzyl-20-+phenyl)-40-+4-nitrophenyl)-
spiro[3H-indole-3,50+40H)-oxazol]-2+1H)-one 12. N-Benzyl-
isatin 0.046 g, 0.194 mmol) and imidoyl chloride 1 0.080 g,
0.291 mmol) taken in 2 mL dry benzene was treated with
triethylamine 0.032 g, 0.321 mmol) under the standard
procedure to afford the title compound 12 as pale yellow
crystals; recrystallised from hexane±dichloromethane. Mp
168±1708C; [Found C, 73.12; H, 4.52; N, 8.63. C29H21N3O4
requires C, 73.25; H, 4.45; N, 8.84%]; nmax KBr) 1732, 1647,
1604, 1522, 1349, 1172, 1021, 848, 753, 692 cm21. dH
300 MHz, CDCl3) 8.10 2H, d, Jˆ7.2 Hz, Ar-H), 8.02 2H,
d, Jˆ8.4 Hz, Ar-H), 7.11±7.59 11H, m, Ar-H), 6.75±6.80
3H, m, Ar-H), 5.79 1H, s, NCH), 4.88 1H, d, Jˆ15.3 Hz,
C6H5CHH), 4.23 1H, d, Jˆ15.3 Hz, C6H5CHH); dC
75 MHz, CDCl3) 171.58, 165.44, 147.82, 143.63, 143.55,
134.85, 132.34, 131.27, 128.99, 128.63, 128.58, 128.14,
128.02, 127.43, 127.03, 126.66, 124.47, 123.74, 123.42,
109.63, 87.14, 79.53, 43.98.
2.2.8. +3R,40R)-1-Benzyl-20-+4-methylphenyl)-40-+4-nitro-
phenyl)spiro[3H-indole-3,50+40H)-oxazol]-2+1H)-one 16.
N-Benzyl isatin 0.044 g, 0.185 mmol) and imidoyl chloride
2 0.080 g, 0.278 mmol) taken in 2 mL dry benzene was
treated with triethylamine 0.030 g, 0.305 mmol) under the
standard procedure to afford the title compound 16 as pale
yellow crystals; recrystallised from hexane±dichloro-
methane. Mp 192±1948C; nmax KBr) 1733, 1650, 1607,
2.2.5. +3R,40R)-1-Methyl-20-+4-methylphenyl)-40-+4-nitro-
phenyl)spiro[3H-indole-3,50+40H)-oxazol]-2+1H)-one 13.
N-Methyl isatin 0.024 g, 0.149 mmol) and imidoyl chloride
2 0.064 g, 0.223 mmol) taken in 2 mL dry benzene was
treated with triethylamine 0.024 g, 0.245 mmol) under the
standard procedure to afford the title compound 13 as pale
yellow crystals; recrystallised from hexane±dichloro-
methane. Mp 213±2158C; nmax KBr) 1725, 1646, 1613,
1520, 1467, 1348, 1235, 1076, 996, 830, 764, 744,
685 cm21; dH 300 MHz, CDCl3) 8.10 2H, d, Jˆ8.4 Hz,
Ar-H), 7.96 2H, d, Jˆ7.8 Hz, Ar-H), 7.19±7.57 m, 7H,
Ar-H), 6.84 1H, d, Jˆ7.7 Hz, Ar-H), 5.77 1H, s, NCH),
2.91 3H, s, NCH3) 2.44 3H, s, C6H4CH3). dC 75 MHz,
CDCl3) 171.53, 165.29, 147.75, 144.31, 144.16, 142.78,
131.23, 129.27, 128.96, 127.74, 127.65, 124.29, 123.85,
123.76, 123.32, 108.74, 86.91, 79.32, 26.04, 21.76. HRMS
EI): M1 found 413.1375. C29H19N3O4 requires 413.1376.
1518, 1349, 1174, 1074, 847, 751, 696 cm21
. dH
300 MHz, CDCl3) 7.98±8.05 4H, m, Ar-H), 7.59 1H, d,
Jˆ7.0 Hz, Ar-H), 7.14±7.39 9H, m, Ar-H), 6.78 3H, br s,
Ar-H), 5.79 1H, s, NCH), 4.89 1H, d, Jˆ15.0 Hz,
C6H5CHH), 4.23 1H, d, Jˆ15.0 Hz, C6H5CHH), 2.44
3H, s, C6H4CH3); dC 75 MHz, CDCl3) 171.72, 165.61,
147.75, 143.72, 143.54, 142.94, 134.87, 131.22, 129.29,
128.91, 128.59, 128.15, 127.95, 127.41, 127.08, 124.44,
123.75, 123.42, 109.63, 87.05, 79.49, 43.95, 21.72; HRMS
EI): M1 found 489.1667. C30H23N3O4 requires 489.1688.
2.2.9. 20-+4-Phenyl)-40-+4-nitrophenyl)spiro[acenaphthyl-
ene-1+2H),50+4H)-oxazol]-2-one 18. Acenaphthenequinone
0.030 g, 0.164 mmol) and imidoyl chloride 1 0.067 g,
0.247 mmol) taken in 2 mL dry benzene was treated with
triethylamine 0.027 g, 0.271 mmol) under the standard
procedure to afford the title compound 18 as colourless
crystals; recrystallised from hexane±dichloromethane. Mp
204±2058C; nmax KBr) 1726, 1651, 1521, 1340, 1272,
1017, 830, 780 cm21. dH 300 MHz, CDCl3) 7.97 2H, d,
Jˆ8.6 Hz, Ar-H), 7.26±8.28 11H, m, Ar-H), 7.13 2H, d,
Jˆ8.5 Hz, Ar-H), 5.99 1H, s, NCH). dC 75 MHz, CDCl3)
197.58, 165.39, 147.57, 144.30, 142.04, 137.22, 132.47,
132.28, 131.98, 130.70, 130.49, 129.23, 129.02, 128.97,
128.59, 128.44, 127.89, 126.69, 123.37, 122.57, 121.99,
2.2.6. +3R,40R)-1-Phenyl-20-+4-methylphenyl)-40-+4-nitro-
phenyl)spiro[3H-indole-3,50+40H)-oxazol]-2+1H)-one 14.
N-Phenyl isatin 0.025 g, 0.112 mmol) and imidoyl chloride
2 0.048 g, 0.168 mmol) taken in 2 mL dry benzene was
treated with triethylamine 0.019 g, 0.184 mmol) under the
standard procedure to afford the title compound 14 as pale
yellow crystals; recrystallised from hexane±dichloro-
methane. Mp 105±1078C; [Found C, 73.55; H, 4.40; N,
8.94. C29H21N3O4 requires C, 73.25; H, 4.45; N, 8.84%];
nmax KBr) 1740, 1651, 1608, 1514, 1344, 1080, 750,

V. Nair et al. / Tetrahedron 58 ꢀ2002) 3003±3007
3007
120.73, 90.16, 79.68; HRMS EI): M1 found 420.1112.
C26H16N2O4 requires 420.1110.
127.90,.126.33, 124.04, 123.67, 123.35, 122.20, 92.60,
78.69, 21.82; HRMS EI): M1 found 460.1420.
C29H20N2O4 requires 460.1423.
2.2.10. 20-+4-Methylphenyl)-40-+4-nitrophenyl)spiro[ace-
naphthylene-1+2H),50+4H)-oxazol]-2-one 19. Acenaph-
thenequinone 0.033 g, 0.181 mmol) and imidoyl chloride
2 0.078 g, 0.271 mmol) taken in 2 mL dry benzene was
treated with triethylamine 0.030 g, 0.305 mmol) under the
standard procedure to afford the title compound 19 as
colourless crystals; recrystallised from hexane±dichloro-
methane. Mp 196±1988C; [Found C, 74.73; H, 4.36; N,
6.48. C27H18N2O4 requires C, 74.64; H, 4.18; N, 6.45%];
nmax KBr) 1707, 1645, 1599, 1517, 1449, 1334, 1096,
994, 916, 834, 751, 694 cm21. dH 300 MHz, CDCl3):
8.25 2H, d, Jˆ7.0 Hz, Ar-H), 8.14 1H, d, Jˆ7.6 Hz,
Ar-H), 7.53±7.81 9H, m, Ar-H), 7.03±7.25 3H, m,
Ar-H), 6.76 2H, d, Jˆ8.5 Hz, Ar-H), 5.63 1H, s, NCH);
dC 75 MHz, CDCl3) 195.34, 165.86, 147.17, 144.10,
137.67, 135.53, 133.43, 132.41, 130.15, 129.07, 129.00,
128.94, 128.66, 128.59, 128.23, 127.74, 126.38, 126.24,
123.97, 123.27, 122.44, 92.58, 78.60.
Acknowledgements
D. S. thanks the CSIR New Delhi for ®nancial assistance.
References
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2.2.11. 20-+4-Phenyl)-40-+4-nitrophenylspiro[oxazole-5+4H),
90+100H)-phenanthren]-100-one 21. Phenanthrenequinone
0.030 g, 0.144 mmol) and imidoyl chloride 1 0.059 g,
0.216 mmol) taken in 2 mL dry benzene was treated with
triethylamine 0.024 g, 0.237 mmol) under the standard
procedure to afford the title compound 21 as colourless
crystals crystals; recrystallised from hexane±dichloro-
methane. Mp 185±1878C; [Found C, 75.51; H, 4.20; N,
5.97. C28H18N2O4 requires C, 75.33; H, 4.06; N, 6.27%];
nmax KBr) 1726, 1645, 1601, 1520, 1348, 1272, 1073,
1014, 829, 785 cm21; dH 300 MHz, CDCl3) 7.70±8.17
10H, m, Ar-H), 7.28 2H, d, Jˆ7.8 Hz, Ar-H), 7.12 2H,
d, Jˆ8.4 Hz, Ar-H), 5.97 1H, s, NCH), 2.44 s, 3H,
C6H5CH3); dC 75 MHz, CDCl3) 197.65, 165.50, 147.59,
144.48, 142.76, 142.02, 137.38, 131.93, 130.79, 130.50,
129.30, 129.22, 128.96, 127.93, 126.62, 123.97, 123.34,
122.50, 120.70, 90.10, 79.73, 21.73.
6. a) Cordell, G. A., Ed.; The Alkaloids: Chemistry and Biology,
Academic: San Diego, 1998; Vol. 5. b) Cui, C.-B.; Kakeya,
H.; Osada, H. Tetrahedron 1996, 52, 12651. c) James,
M. N. G.; Williams, G. J. B. Can. J. Chem. 1972, 50, 2407.
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7. Hansen, H.-J.; Heimgartner, H. 1,3-Dipolar Cycloaddition
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8. Ibata, T.; Fukushima, K. Chem. Lett. 1992, 2197.
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10. Lerestif, J. M.; Bazureau, J. P.; Hamelin, J. Synlett 1995, 647
and references cited therein.
11. Ovcharenko, A. A.; Chertkov, V. A.; Karchava, A. V.;
Yurovskaya, M. A. Tetrahedron Lett. 1997, 38, 6933.
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2.2.12. 20-+4-Methylphenyl)-40-+4-nitrophenyl)spiro[oxa-
zole-5+4H),90+100H)-phenanthren]-100-one 22. Phenan-
threnequinone 0.030 g, 0.144 mmol) and imidoyl chloride
2 0.062 g, 0.216 mmol) taken in 2 mL dry benzene was
treated with triethylamine 0.024 g, 0.237 mmol) under the
standard procedure to afford the title compound 22 as
colourless crystals; recrystallised from hexane±dichloro-
methane. Mp 204±2068C; nmax KBr) 1706, 1646, 1593,
1513, 1454, 1341, 1268, 1089, 830, 744, 718 cm21. dH
300 MHz, CDCl3) 8.12±8.15 3H, m, Ar-H), 7.74±7.80
4H, m, Ar-H), 7.51±7.59 2H, m, Ar-H), 7.35 2H, d,
Jˆ7.9 Hz, Ar-H), 7.03±7.18 3H, m, Ar-H), 6.76 2H, d,
Jˆ8.5 Hz, Ar-H), 5.61 1H, s, NCH), 2.49 3H, s,
C6H5CH3); dC 75 MHz, CDCl3) 195.53, 166.06, 147.22,
144.34, 143.06, 137.78, 135.55, 133.62, 130.22, 129.48,
129.12, 129.08, 129.01, 128.73, 128.65, 128.34,
14. Tsuge, O.; Kanamasa, S.; Yamada, T.; Matsuda, K. J. Org.
Chem. 1987, 52, 2523.
15. Huisgen, R.; Stangl, H.; Sturm, H. J.; Raab, R.; Bunge, K.
Chem. Ber. 1972, 105, 1258.
16. The X-ray data for the adducts 6 and 19 have been deposited at
the Cambridge Crystallographic Data Center and has been
assigned numbers CCDC 166424 and CCDC 176281,
respectively.
17. Garden, S. J.; Torres, J. C.; Silva, L. E.; Pinto, A. C. Synth.
Commun. 1998, 28, 1679.