Facile one-pot synthesis of novel tricyclic dibenzoheterocycles via the dianion protocol of ditopic ligands

Article abstract of DOI:10.1080/00397910802638545

In our ongoing studies on the synthesis of new heterocyclic ring systems via a dianion intermediate, we herein describe the preparation of novel dibenzoazadioxoninone, dibenzoazadioxoninethione, dibenzoazadioxocine, dibenzoazadioxacycloundecine, dibenzoaz

Full text of DOI:10.1080/00397910802638545

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Facile One-Pot Synthesis
of Novel Tricyclic
Dibenzoheterocycles via the
Dianion Protocol of Ditopic
Ligands
Anil K. Singh a , Rakesh Tripathi a , Rajiv K. Verma a
& Maya S. Singh a
a Department of Chemistry, Faculty of Science,
Banaras Hindu University, Varanasi, India
Version of record first published: 13 May 2009.
To cite this article: Anil K. Singh, Rakesh Tripathi, Rajiv K. Verma & Maya S. Singh
(2009): Facile One-Pot Synthesis of Novel Tricyclic Dibenzoheterocycles via the
Dianion Protocol of Ditopic Ligands, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 39:12, 2116-2124
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Synthetic Communications1, 39: 2116–2124, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802638545
Facile One-Pot Synthesis of Novel Tricyclic
Dibenzoheterocycles via the Dianion
Protocol of Ditopic Ligands
Anil K. Singh, Rakesh Tripathi, Rajiv K. Verma, and Maya S. Singh
Department of Chemistry, Faculty of Science, Banaras Hindu University,
Varanasi, India
Abstract: In our ongoing studies on the synthesis of new heterocyclic ring
systems via a dianion intermediate, we herein describe the preparation of novel
dibenzoazadioxoninone,
dibenzoazadioxoninethione,
dibenzoazadioxocine,
dibenzoazadioxacycloundecine, dibenzoazadioxacyclododecine, dibenzoaza-2-
oxodioxaphosphonine, and dibenzoaza-2-oxo-1,3-thioxaphosphonine in good
yields.
Keywords: Dianion, dielectrophiles, ditopic Schiff base ligand, nucleophilic
substitution, tricyclic dibenzoheterocycles
INTRODUCTION
Medium-size polyheterocyclic rings containing nitrogen, phosphorus,
oxygen, and sulfur are rare in the literature. Benzodiazepines have been
synthesized under solvent-free conditions.[1] Dibenzoxazocine and diben-
zothiazocine[2] have been synthesized. Monocyclic medium-ring nitrogen
heterocycles are an extremely important class of compounds, which occur
in a range of natural and synthetic products.[3] Medium-sized rings are
generally the most difficult to prepare using conventional cyclization
methods.[4] To the best of our knowledge, there are no reports of the
Received April 16, 2008.
Address correspondence to Maya S. Singh, Department of Chemistry, Faculty
of Science, Banaras Hindu University, Varanasi 221 005, India. E-mail:
mssinghbhu@yahoo.co.in
2116

Novel Tricyclic Dibenzoheterocycles
2117
Scheme 1. Synthesis of tricyclic dibenzoheterocycles.
synthesis of heterocycles (Scheme 1). With this background, the goal of
the present article is to provide cyclization reactions of dianions. For this
purpose, we have focused our efforts on selected examples of cyclization
reactions that follow 1:1 stoichiometry of dianion and electrophile.
RESULTS AND DISCUSSION
It is known that the Schiff bases prepared from salicylaldehyde and
aromatic amines possess the E-configuration as a result of H-bonding
between the hydroxyl and the nitrogen of the imine group.[5] Our syn-
thesis involves the initial formation of dianion 2 from sequential depro-
tonations of the acidic protons of salicylidene-o-aminophenol 1a and
salicylidene-o-aminothiophenol 1b by sodium hydride. The remote 1,8-
dianion thus generated attacks to a variety of dielectrophilic reagents,
leading to the formation of tricyclic compounds 3–16 (Scheme 1).
The spectral analysis showed infrared (IR) bands for C¼N, C¼O,
and C¼S groups in their respective regions, which are listed in the experi-
mental part. The stretching frequency for P¼O in compounds 8, 9 and 15,
16 appears at 1274 and 1272 cmꢀ1, respectively.
The NMR (1H, 13C, and 31P) spectra of the compounds 3–16 were
consistent with the suggested structures. The two phenyl rings display
signals in the NMR spectra in the expected region. Ethylene protons
attached to oxygen resonate as triplet (J ¼ 8.2 Hz) centered on 3.87 ppm
integrating for four protons. As anticipated, the 13C NMR spectra

2118
A. K. Singh et al.
support the structures by having the signals for the carbon atoms present
in the appropriate regions. Comparison of the 13C NMR spectra for the
parent benzaldehyde and those of the Schiff base 1 allows rather simple
assignment of the observable signals of the carbon atoms to correspond-
ing groups. Thus, the carbon signals in the region of sp2-hybridized
atoms evidently correspond to the imino group (CH¼N). In all cases,
the mass spectra showed peaks for the molecular ion corresponding to
their molecular weight.
EXPERIMENTAL
Ethyl chloroformate, carbon disulfide, 1,2-dichloroethane, 1,3-dibromo-
propane, 1,4-dibromobutane, methyldichlorophosphate, and phenyldi-
chlorophosphate were used as obtained from commercial sources.
Salicylidene-o-aminophenol and salicylidene-o-aminothiophenol were
prepared by the literature method. All reactions were carried out under
a dry, oxygen-free nitrogen or argon atmosphere. All solvents (analytical
reagent or extra pure grade) used for spectroscopic and other physical
studies were further purified by literature methods. Tetrahydrofuran
(THF) was distilled from sodium=benzophenone immediately prior to
use. Thin-layer chromatography (TLC) was used to monitor the progress
of the reactions. Infrared (IR) spectra were recorded as KBr discs on a
Fourier transform (FT)–IR Perkin-Elmer model RX-I spectrophot-
ometer. Melting points were determined using a calibrated thermometer
on a Remi melting-point apparatus and are uncorrected. Elemental
analyses were performed by Central Drug Research Institute, Lucknow.
NMR (1H, 13C, and 31P) spectra were recorded on a Jeol AL 300 instru-
ment. The chemical shifts are reported in parts per million (ppm)
downfield from tetramethylsilane (TMS) and referenced to residual
protons of dimethyl sulfoxide (DMSO-d6) (d 2.49). Mass spectra (MS)
were recorded at 70 eV ionizing voltage on a Jeol-D300 MS instrument.
Typical Procedure for the Synthesis of Diatopic Ligands
Salicylaldehyde (6.10 g, 50 mmol) was added to a methanolic solution of
o-aminophenol (5.45 g, 50 mmol). The reaction mixture was shaken on a
shaker for half an hour. The resulting orange-colored precipitate was
filtered and washed with methanol. The Schiff base was recrystallized
from a mixture of chloroform and petroleum ether. The yield of pure
salicylidene-o-aminophenol (1a) was 8.52 g (80%), mp 136 ꢁC (mp 137 ꢁC).
Similarly, salicylidene-o-aminothiophenol (1b) was synthesized from

Novel Tricyclic Dibenzoheterocycles
2119
salicylaldehyde (6.10 g, 50 mmol) and o-aminothiophenol (6.25 g,
1
50 mmol) in 76% yield, mp 154 ꢁC (mp 155 ꢁC). The H NMR and 13C
NMR data are consistent with the literature[6] values.
11,13-Dioxa-5-aza-dibenzo[a,e]cyclononen-12-one (3)
A solution of salicylidene-o-aminophenol (426 mg, 2 mmol) in dry THF
(25 mL) was added to a suspension of sodium hydride (96 mg, 4 mmol)
in dry THF (10 mL). After completion of the addition, the solution
was stirred at reflux for 5 h. The mixture was allowed to attain room tem-
perature. Ethylchloroformate (217 mg, 2 mmol) was added dropwise to
the reaction vessel, and the contents were further stirred at reflux for
30 minutes. TLC confirmed the completion of the reaction. The reaction
mixture was concentrated using a rotary evaporator, and the residue was
purified by column chromatography on silica gel (ethylacetate=hexane,
1:8) to afford 325 mg (60%); mp 118–119 ꢁC; IR (KBr, cmꢀ1) 1752,
1
1645, 1533, 1482, 1390, 1247, 1086; H NMR (300 MHz, DMSO-d6): d
8.32 (s, 1H, CH¼N), 8.12–7.26 (m, 8H, H-Ar); 13C NMR (75 MHz,
DMSO-d6): d 166.85, 164.97, 158.93, 147.84, 143.42, 133.66, 132.58,
127.63, 127.56, 118.62, 118.44, 116.60, 115.27; MS (EI, 70 eV): m=z 239
(Mþ, 24). Anal. calcd. for C14H9NO3: C, 70.29; H, 3.79; N, 5.86. Found:
C, 70.64; H, 4.22; N, 5.71.
11,13-Dioxa-5-aza-dibenzo[a,e]cyclononen-12-thione (4)
The same procedure as for 3 with 426 mg (2 mmol) of salicylidene-o-
aminophenol, 96 mg (4 mmol) of sodium hydride, and 152 mg (2 mmol)
of carbon disulphide yielded 4 (352 mg, 69%); mp 93–95 ꢁC; IR (KBr,
1
cmꢀ1) 1654, 1490, 1395, 1262, 1235, 914; H NMR (300 MHz, DMSO-
d6): d 8.26 (s, 1H, CH¼N), 8.06–7.18 (m, 8H, H-Ar); 13C NMR
(75 MHz, DMSO-d6): d 180.36, 164.53, 158.48, 148.52, 146.51, 133.62,
132.41, 127.65, 127.68, 118.61, 118.43, 116.95, 115.68; MS (EI, 70 eV):
m=z 255 (Mþ, 21). Anal. calcd. for C14H9NO2S: C, 65.87; H, 3.55; N,
5.49. Found: C, 66.26; H, 3.89; N, 5.69.
6,7-Dihydro-5,8-dioxa-13-aza-dibenzo[a,f ]cyclodecene (5)
The same procedure as for 3 with 426 mg (2 mmol) of salicylidene-o-
aminophenol, 96 mg (4 mmol) of sodium hydride, and 198 mg (2 mmol)
of 1,2-dichloroethane afforded 5 (330 mg, 69%); mp 178–180 ꢁC; IR
(KBr, cmꢀ1) 1634, 1630, 1522, 1493, 1460, 1431, 1391, 1321, 1249,

2120
A. K. Singh et al.
1
1238, 1172, 1148, 1093; H NMR (300 MHz, DMSO-d6): d 8.34 (s, 1H,
CH¼N), 7.96–7.12 (m, 8H, H-Ar), 3.87 (t, J ¼ 8.2 Hz, 4H, OCH2);
13C NMR (75 MHz, DMSO-d6): d 164.43, 159.16, 148.58, 146.23,
133.51, 132.46, 127.54, 123.87, 119.04, 117.47, 114.87, 111.71, 110.41,
58.84, 58.62; MS (EI, 70 eV): m=z 239 (Mþ, 18). Anal. calcd. for
C15H13NO2: C, 75.30; H, 5.48; N, 5.85. Found: C, 75.71; H, 5.85; N, 6.00.
7,8-Dihydro-6H-5,9-dioxa-14-aza-dibenzo[a,e]cycloundecene (6)
The same procedure as for 3 with salicylidene-o-aminophenol (426 mg,
2 mmol), NaH (96 mg, 4 mmol), and 1,3-dibromopropane (404 mg,
2 mmol) afforded 6 (360 mg, 71%); mp 195–197 ꢁC; IR (KBr, cmꢀ1
)
1
1647, 1627, 1593, 1483, 1449, 1326, 1241, 1211, 1173, 1098; H NMR
(300 MHz, DMSO-d6): d 8.36 (s, 1H, CH¼N), 7.88–6.85 (m, 8H,
H-Ar), 3.89 (t, 4H, J ¼ 8.2 Hz, OCH2), 1.35 (m, 2H, CH2); 13C NMR
(75 MHz, DMSO-d6): d 164.86, 158.75, 148.67, 144.10, 132.96, 132.45,
127.52, 123.73, 119.31, 117.42, 114.78, 110.86, 109.82, 59.74, 59.62,
20.68; MS (EI, 70 eV): m=z 253 (Mþ, 24). Anal. calcd. for C16H15NO2:
C, 75.87; H, 5.97; N, 5.53. Found: C, 76.16; H, 6.31; N, 5.67.
6,7,8,9-Tetrahydro-5,10-dioxa-15-aza-dibenzo[a,e]cyclododecene (7)
The same procedure as for 3 with salicylidene-o-aminophenol (426 mg,
2 mmol), NaH (96 mg, 4 mmol), and 1,4-dibromobutane (432mg, 2 mmol)
yielded 7 (360mg, 67%); mp 180–182 ꢁC; IR (KBr, cmꢀ1) 1632, 1462, 1377,
1
1247, 1169, 1079, 1054; H NMR (300MHz, DMSO-d6): d 8.33 (s, 1H,
CH¼N), 7.96–6.80 (m, 8H, H-Ar), 3.85 (t, J ¼ 8.2 Hz, 4H, OCH2), 1.36–
1.30 (m, 4H, CH2); 13C NMR (75 MHz, DMSO-d6): d 164.81, 160.27,
148.61, 145.20, 133.25, 132.98, 127.61, 124.29, 118.86, 118.25, 115.95,
111.23, 108.94, 59.84, 59.57, 20.98, 20.65; MS (EI, 70eV): m=z 267 (Mþ,
19). Anal. calcd. for C17H17NO2: C, 76.39; H, 6.41; N, 5.24. Found: C,
76.67; H, 6.18; N, 5.44.
12-Methoxy-11,13-dioxa-5-aza-12-phospha-dibenzo
[a,e]cyclononen-12-oxide (8)
Methyldichlorophosphate (298 mg, 2 mmol) was added to a solution of
dianion 2 prepared as before from salicylidene-o-aminophenol (426 mg,
2 mmol) and NaH (96 mg, 4 mmol) in dry THF, and the reaction mixture
was refluxed for 1 h. The salt was filtered off, and the solvent was
removed using a rotary evaporator. The crude mixture was purified by

Novel Tricyclic Dibenzoheterocycles
2121
column chromatography using ethylacetate=hexane (1:4) to afford 8
(400 mg, 70%); mp 221–223 ꢁC; IR (KBr, cmꢀ1) 1644, 1578, 1521, 1435,
1
1301, 1274, 1205, 1071, 1048; H NMR (300 MHz, DMSO-d6): d 8.36
(s, 1H, CH¼N), 8.07–6.85 (m, 8H, H-Ar), 3.20 (s, 3H, OCH3); 13C
NMR (75 MHz, DMSO-d6): d 164.54, 160.22, 149.21, 147.20, 132.16,
131.95, 128.06, 127.91, 126.29, 125.17, 119.66, 119.53, 117.45, 56.34;
31P NMR (121 MHz, DMSO-d6): d ꢀ11.91; MS (EI, 70 eV): m=z 289
(Mþ, 15). Anal. calcd. for C14H12NO4P: C, 58.14; H, 4.18; N, 4.84.
Found: C, 58.54; H, 4.58; N, 5.01.
12-Phenoxy-11,13-dioxa-5-aza-12-phospha-dibenzo
[a,e]cyclononen-12-oxide (9)
Same procedure as for 7 with salicylidene-o-aminophenol (426 mg,
2 mmol), NaH (96 mg, 4 mmol), and phenyldichlorophosphate (422 mg,
2 mmol) yielded 9 (456 mg, 65%); mp 242 ꢁC (d), IR (KBr, cmꢀ1) 1642,
1
1609, 1498, 1472, 1362, 1274, 1230, 1164, 1021; H NMR (300 MHz,
DMSO-d6): d 8.13 (s, 1H, CH¼N), 7.86–6.92 (m, 13H, H-Ar); 13C
NMR (75 MHz, DMSO-d6): d 164.74, 160.42, 148.21, 146.26, 133.63,
132.58, 131.55, 131.10, 127.64, 127.22, 119.26, 119.05, 118.16, 117.61,
117.45, 117.32; 31P NMR (121 MHz, DMSO-d6): d ꢀ18.91; MS (EI,
70 eV): m=z 351 (Mþ, 17). Anal. calcd. for C19H14NO4P: C, 64.96; H,
4.02; N, 3.99. Found: C, 65.44; H, 4.43; N, 4.09.
11-Oxa-13-thia-5-aza-dibenzo[a,e]cyclononen-12-one (10)
A solution of salicylidene-o-aminothiophenol (458 mg, 2 mmol) in dry
THF (25 mL) was added to a suspension of sodium hydride (96 mg,
4 mmol) in dry THF (10 mL). After completion of the addition, the solu-
tion was stirred at reflux for 6 h. The mixture was allowed to attain room
temperature. Ethylchloroformate (217 mg, 2 mmol) was added dropwise
to the reaction vessel, and the contents were further stirred at reflux
for 1 h. TLC confirmed the completion of the reaction. The reaction mix-
ture was concentrated using a rotary evaporator, and the residue was
chromatographed on silica gel using ethylacetate=hexane (1:10) to give
10 (332 mg, 65%); mp 125–127 ꢁC; IR (KBr, cmꢀ1) 1747, 1625, 1503,
1
1452, 1380, 1263, 1115, 1046; H NMR (300 MHz, DMSO-d6): d 8.22
(s, 1H, CH¼N), 7.88–6.96 (m, 8H, H-Ar); 13C NMR (75 MHz,
DMSO-d6): d 166.65, 164.87, 158.93, 147.73, 143.22, 133.66, 132.88,
130.57, 127.73, 127.61, 127.52, 119.19, 119.07, 116.95, 115.65; MS (EI,
70 eV): m=z 255 (Mþ, 21). Anal. calcd. for C14H9NO2S: C, 65.87; H,
3.55; N, 5.49. Found: C, 66.30; H, 3.96; N, 5.65.

2122
A. K. Singh et al.
11-Oxa-13-thia-5-aza-dibenzo[a,e]cyclononen-12-thione (11)
A solution of salicylidene-o-aminothiophenol (458 mg, 2 mmol) in dry
THF (25 mL) was added to a suspension of sodium hydride (96 mg,
4 mmol) in dry THF (10 mL). After completion of the addition, the solu-
tion was stirred at reflux for 6 h. The mixture was allowed to attain room
temperature. Carbon disulphide (152 mg, 2 mmol) was added dropwise to
the reaction vessel, and the contents were further stirred at reflux for 1 h.
TLC confirmed the completion of the reaction. The reaction mixture was
concentrated using a rotary evaporator, and the residue was chroma-
tographed on silica gel using ethylacetate=hexane (1:10) to give 11
(370 mg, 68%); mp 102–104 ꢁC; IR (KBr, cmꢀ1) 1631, 1529, 1463, 1377,
1
1276, 1223, 1139, 1116; H NMR (300 MHz, DMSO-d6): d 8.29 (s, 1H,
CH¼N), 7.94–6.84 (m, 8H, H-Ar); 13C NMR (75 MHz, DMSO-d6): d
179.76, 164.73, 158.28, 147.62, 145.51, 133.76, 132.83, 130.99, 127.85,
127.48, 126.94, 118.85, 118.63, 116.25, 115.63; MS (EI, 70 eV): m=z 271
(Mþ, 14). Anal. calcd. for C14H9NOS2: C, 61.97; H, 3.34; N, 5.16. Found:
C, 62.24; H, 3.76; N, 5.27.
6,7-Dihydro-5-oxa-8-thia-13-aza-dibenzo[a,f ]cyclodecene (12)
The same procedure as for 10 with 458 mg (2 mmol) of salicylidene-o-
aminothiophenol, 96 mg (4 mmol) of NaH, and 198 mg (2 mmol) of 1,2-
dichloroethane yielded 12 (357 mg, 70%); mp 165–167 ꢁC; IR (KBr,
cmꢀ1) 1630, 1590, 1490, 1420, 1319, 1261; 1H NMR (300 MHz,
DMSO-d6): d 8.29 (s, 1H, CH¼N), 8.06–6.64 (m, 8H, H-Ar), 3.86
(t, J ¼ 8.2 Hz, 2H, OCH2), 3.12 (t, J ¼ 7.8 Hz, 2H, SCH2); 13C NMR
(75 MHz, DMSO-d6): d 164.57, 159.61, 148.58, 133.81, 132.86, 132.07,
127.84, 127.67, 126.87, 119.34, 117.47, 114.47, 111.21, 110.01, 56.84,
56.22; MS (EI, 70 eV): m=z 255 (Mþ, 16). Anal. calcd. for C15H13NOS:
C, 70.56; H, 5.13; N, 5.49. Found: C, 70.83; H, 4.85; N, 5.61.
7,8-Dihydro-6H-5-oxa-9-thia-14-aza-dibenzo[a,e]cycloundecene (13)
Same procedure as for 10 with salicylidene-o-aminothiophenol (456 mg,
2 mmol), NaH (96 mg, 4 mmol), and 1,3-dibromopropane (404 mg,
2 mmol) gave 13 (377 mg, 70%); mp 188–190 ꢁC; IR (KBr, cmꢀ1) 1627,
1
1587, 1493, 1442, 1346, 1231, 1205, 1170, 1088; H NMR (300 MHz,
DMSO-d6): d 8.30 (s, 1H, CH¼N), 7.97–6.72 (m, 8H, H-Ar), 3.92 (t,
2H, J ¼ 8.2 Hz, OCH2), 3.17 (t, J ¼ 7.8 Hz, 2H, SCH2), 1.42 (m, 2H,
CH2); 13C NMR (75 MHz, DMSO-d6): d 164.16, 159.05, 148.97,

Novel Tricyclic Dibenzoheterocycles
2123
145.64, 133.96, 128.45, 128.22, 123.70, 119.61, 117.62, 116.78, 115.86,
58.72, 58.62, 20.28; MS (EI, 70 eV): m=z 269 (Mþ, 27). Anal. calcd. for
C16H15NOS: C, 71.34; H, 5.61; N, 5.20. Found: C, 71.71; H, 5.93; N, 5.45.
6,7,8,9-Tetrahydro-5-oxa-10-thia-15-aza-dibenzo
[a,e]-cyclododecane (14)
A solution of salicylidene-o-aminothiophenol (458 mg, 2 mmol) in dry
THF (25 mL) was added to a suspension of sodium hydride (96 mg,
4 mmol) in dry THF (10 mL). After completion of the addition, the solu-
tion was stirred at reflux for 6 h. The mixture was allowed to attain room
temperature. 1,4-Dibromobutane (432 mg, 2 mmol) was added dropwise
to the reaction vessel, and the contents were further stirred at reflux
for 1 h. TLC confirmed the completion of the reaction. The reaction mix-
ture was concentrated using a rotary evaporator, and the residue was
chromatographed on silica gel using ethylacetate=hexane (1:10) to give
14 (380 mg, 67%); mp 176–178 ꢁC; IR (KBr, cmꢀ1) 1632, 1492, 1420,
1396, 1262, 1249; 1H NMR (300 MHz, DMSO-d6): d 8.27 (s, 1H,
CH¼N), 7.95–6.73 (m, 8H, H-Ar), 3.84 (t, J ¼ 8.2 Hz, 2H, OCH2), 3.15
(t, J ¼ 7.8 Hz, 2H, SCH2), 1.23 (m, 4H, CH2); 13C NMR (75 MHz,
DMSO-d6): d 164.87, 160.21, 147.90, 133.75, 133.18, 132.88, 127.83,
126.92, 119.26, 118.95, 116.95, 111.53, 108.74, 57.84, 57.57, 20.88,
20.69; MS (EI, 70 eV): m=z 283 (Mþ, 18). Anal. calcd. for C17H17NOS:
C, 72.05; H, 6.05; N, 4.94. Found: C, 72.47; H, 6.38; N, 5.10.
12-Methoxy-11-oxa-13-thia-5-aza-12-phospha-dibenzo
[a,e]-cyclononene-12-oxide (15)
Methyldichlorophosphate (298 mg, 2 mmol) was added to a solution of
dianion 2 prepared as before from salicylidene-o-aminothiophenol
(426 mg, 2 mmol) and NaH (96 mg, 4 mmol) in dry THF, and the reaction
mixture was refluxed for 1.5 h. The salt was filtered off, and the solvent
was removed using a rotary evaporator. The crude mixture was purified
by column chromatography using ethylacetate=hexane (1:4) to afford 15
(434 mg, 71%); mp 253 ꢁC (d); IR (KBr, cmꢀ1) 1624, 1573, 1481, 1445,
1
1381, 1272, 1232, 1208, 1071, 1032; H NMR (300 MHz, DMSO-d6): d
8.27 (s, 1H, CH¼N), 7.87–6.72 (m, 8H, H-Ar), 3.27 (s, 3H, OCH3);
13C NMR (75 MHz, DMSO-d6): d 164.64, 160.28, 149.21, 147.18,
133.46, 133.25, 132.73, 127.86, 127.41, 126.36, 119.26, 118.33, 117.95,
117.43, 55.34; 31P NMR (121 MHz, DMSO-d6): d ꢀ12.01; MS (EI,
70 eV): m=z 305 (Mþ, 15). Anal. calcd. for C14H12NO3SP: C, 55.08; H,
3.96; N, 4.59. Found: C, 55.42; H, 4.33; N, 4.71.

2124
A. K. Singh et al.
12-Phenoxy-11-oxa-13-thia-5-aza-12-phospha-dibenzo
[a,e]cyclononen-12-oxide (16)
The same procedure as for 15 with salicylidene-o-aminothiophenol (426mg,
2 mmol), NaH (96 mg, 4 mmol), and phenyldichlorophosphate (422mg,
2 mmol) yielded 16 (514mg, 70%); mp 228–230 ꢁC; IR (KBr, cmꢀ1) 1638,
1
1587, 1488, 1372, 1315, 1272, 1220, 1134, 1031; H NMR (300MHz,
DMSO-d6): d 8.18 (s, 1H, CH¼N), 7.98–6.84 (m, 13H, H-Ar); 13C NMR
(75 MHz, DMSO-d6): d 164.78, 160.54, 148.56, 133.43, 132.38, 131.62,
131.23, 127.86, 127.42, 119.74, 119.52, 119.21, 118.36, 117.41, 117.25,
117.02; 31P NMR (121MHz, DMSO-d6): d ꢀ18.51; MS (EI, 70eV): m=z
367 (Mþ, 17). Anal. calcd. for C19H14NO3SP: C, 62.12; H, 3.84; N, 3.81.
Found: C, 62.34; H, 4.23; N, 4.01.
ACKNOWLEDGMENTS
We are grateful for financial support of this work from the Council of
Scientific and Industrial Research (CSIR) and Department of Science
and Technology (DST), New Delhi, India.
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