Syntheses and antimicrobial activity of some novel 6-substituted dibenzo[d,f][1,3,2]dioxaphophepin-6-oxides, sulfides, and selenides

Article abstract of DOI:10.1080/00397910701265697

6-Substituted-dibenzo[d,f][1,3,2]dioxaposphepin-6-oxides, sulfides, and selenides (5a-i, 6a-d, and 7a-d) were synthesized by reacting 2,2′-biphenol (1) with phosphorus tribromide in the presence of triethylamine at 0-30°C and subsequent reaction of the mo

Full text of DOI:10.1080/00397910701265697

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Syntheses and Antimicrobial Activity of
Some Novel 6‐Substituted Dibenzo[d, f]
[1,3,2]dioxaphophepin‐6‐oxides, Sulfides,
and Selenides
P. Haranath a , V. Sreedhar Kumar b , C. Suresh Reddy b , C. Naga Raju b & C.
Devendranath Reddy b
a Department of Organic Chemistry , University of Murcia , Murcia, Spain
b Department of Chemistry , Sri Venkateswara University , Tirupati, India
Published online: 22 May 2007.
To cite this article: P. Haranath , V. Sreedhar Kumar , C. Suresh Reddy , C. Naga Raju & C.
Devendranath Reddy (2007) Syntheses and Antimicrobial Activity of Some Novel 6‐Substituted
Dibenzo[d, f][1,3,2]dioxaphophepin‐6‐oxides, Sulfides, and Selenides, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 37:10, 1697-1708, DOI:
10.1080/00397910701265697
To link to this article: http://dx.doi.org/10.1080/00397910701265697
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Synthetic Communicationsw, 37: 1697–1708, 2007
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910701265697
Syntheses and Antimicrobial Activity of
Some Novel 6-Substituted
Dibenzo[d, f ][1,3,2]dioxaphophepin-6-
oxides, Sulfides, and Selenides
P. Haranath
Department of Organic Chemistry, University of Murcia, Murcia, Spain
V. Sreedhar Kumar, C. Suresh Reddy, C. Naga Raju, and
C. Devendranath Reddy
Department of Chemistry, Sri Venkateswara University, Tirupati, India
Abstract: 6-Substituted-dibenzo[d, f ][1,3,2]dioxaposphepin-6-oxides, sulfides, and
selenides (5a–i, 6a–d, and 7a–d) were synthesized by reacting 2,20-biphenol (1)
with phosphorus tribromide in the presence of triethylamine at 0–308C and subsequent
reaction of the monobromide (2) with different Grignard reagents (3) at room tempera-
ture. The products (4) were converted to corresponding oxides, sulfides, and selenides
(5a–i, 6a–d, and 7a–d) by oxidation with H2O2 at room temperature and refluxing
with sulfur and selenium respectively. The chemical structures of all the products
were confirmed by analytical, IR, NMR (1H, 13C, and 31P), and mass spectral data.
Most of these compounds exhibited moderate antimicrobial activity.
Keywords: Dioxaphosphepins, selenides, sulfides
INTRODUCTION
The organophosphate moiety is an important pharmacophore in agricultural
and pharmaceutical compounds.[1] Phosphocin/phosphepin and their related
Received June 7, 2006
Address correspondence to P. Haranath, Department of Organic Chemistry,
University of Murcia, Campus of Espinardo, E-30100 Murcia, Spain. E-mail:
haranath@um.es
1697

1698
P. Haranath et al.
derivatives containing this group represent an important class of pesticides,
antibiotics, herbicides, and antiviral agents.[2] Some of them are well
known for their ecofriendly insecticidal activity[3] because they degrade
hydrolytically and enzymatically to nontoxic residues. Discovery of their
fungicidal properties constitutes a recent development[4] that made them
more important.
RESULTS AND DISCUSSION
Preparation of the seven-membered phosphonate heterocyclic compounds
suchsubstituted-dibenzo[d,f ][1,3,2]dixoaposphepin-6-oxides, sulfides, and
selenides (6a–d and 7a–d) was accomplished in three steps. The synthetic
route (Scheme 1) involves the initial cyclization of equimolar quantities of
2,20-biphenol (1) with phosphorus tribromide in the presence of triethylamine
in dry tetrahydrofuran (THF) to the corresponding phosphorobromodite, 2.
On subsequent reaction with different substituted Grignard reagents (3a–i)
in dry THF (50 mL), this formed the compounds 4a–i. They were further
converted to corresponding oxides (5a–i), sulfides (6a–d), and selenides
Scheme 1.

Syntheses and Antimicrobial Activity
1699
(7a–d) by reaction with hydrogen peroxide, sulfur, and selenium respectively
(Scheme 1).
Their synthetic and analytical data are given in Table 1 and IR, NMR, and
mass spectral data of all compounds[5–12] are given in Tables 2–6 respectively.
The spectral data agree with the proposed structures for all the synthesized
compounds.
Interestingly, only three side chain carbons, C-10, C-20, and C-30, experi-
2
0
0
enced coupling with phosphorus, JP-C-1 ¼ 131.6–140.7, JP-C-2 ¼ 4.7–5.2,
3
and JP-C-3 ¼ 4.7–15.6 Hz. The C-40 and other carbons farther from phos-
0
phorus did not show any coupling with it. The significance of this high–
low–high coupling profile is yet to be understood in P-alkyl side chains
systems of type I. Perhaps this may arise at least in part from g-type inter-
actions as illustrated.[13]
The 31P NMR chemical shifts[14,15] of P(III) derivatives appeared upfield
when compared to those of 5, 6, and 7 P(V) compounds.[16]
Mass spectral data of these compounds are given in Table 6, and their
general fragmentation patterns are rationalized in the Scheme 2,[17] with
respect to compounds 5d, 6d, and 7d as typical examples. They exhibited
the molecular ions indicating the dibenzo[d, f ][1,3,2]dioxaphosphepin-6-
oxide, sulfide, and selenide system is stable. On extensive clearage of the diox-
aphosphepin ring system, the molecular ion found characteristic daughter ions
[M-PO2X]þ, [M-PhX]þ, [M-PhPOX]þ, [M-PhO2X]þ, [M-PhPO2]þ, and
[M-PhPX]þ at their respective m/z values, and their appearance proves
their proposed structure.
ANTIMICROBIAL ACTIVITY
All the compounds 5a–i, 6a–d, and 7a–d were screened for their antibacter-
ial activity against the growth of Staphlococcus aureus and Escherichia coli at
concentrations of 100 mg/disc, 50 mg/disc, and 25 mg/disc.[18,19] The oxides
(5a–i) and the sulfides (6a–d) showed good antibacterial activity against both
bacteria when compared with that of the standard, but the selenides (7a–d)
showed more activity than their corresponding oxides/sulfides and interest-
ingly than even the standard (Table 7).
All the compounds 5a–i, 6a–d, and 7a–d were tested for their antifungal
activity against the growth of Aspergillus niger and Helminthosporium oryzae
at concentrations of 100 mg/disc, 50 mg/disc, and 25 mg/disc.[20] When
compared with reference compound oxides, 5a–i showed low antifungal
activity against the growth of both the fungi at two different concentrations,
but the sulfides (6a–d) and selenides (7a–d) showed more activity against
the growth of both the fungi (Table 8).
In both cases, the order of activity of their antimicrobial activity increases
from oxides to selenides in the order O . S . Se.

Table 1. Synthetic and analytical data of 6-(substituted) dibenzo[d, f ][1,3,2] dioxaposphepin-6-oxides,
sulfides, and selenides (5a–i, 6a–d, and 7a–d)
Elemental analysis; found
(calcd.) (%)
Molecular
Compd.
Mp (8C)
Yield (%)
formula
C
H
5a
5b
5c
5d
5e
5f
127–128
137–140
148–149
218–219
167–168
162–163
182–184
120–121
140–141
139–140
148–149
218–219
140–141
139–140
148–149
218–219
149–151
72
80
81
86
84
59
60
81
82
80
82
86
81
79
72
76
81
C13H11O3P
C14H13O3P
C15H15O3P
C15H15O3P
C16H17O3P
C14H11O3P
C15H13O3P
C14H12O3PCl
C18H13O3P
C14H13O2PS
C15H15O2PS
C15H15O2PS
C18H13O2PS
C14H13O2PSe
C15H15O2PSe
C15H15O2PSe
C18H13O2PSe
63.24 (63.42)
64.42 (64.62)
65.44 (65.69)
65.89 (65.69)
66.86 (66.66)
65.32 (65.12)
66.34 (65.12)
57.28 (57.06)
69.91 (70.13)
61.01 (60.86)
61.92 (62.06)
62.18 (62.06)
66.37 (66.66)
52.18 (52.03)
53.61 (53.43)
53.36 (53.43)
58.41 (58.24)
4.46 (4.50)
5.02 (5.04)
5.53 (5.51)
5.49 (5.51)
5.96 (5.51)
4.30 (4.29)
4.79 (4.81)
4.11 (4.10)
4.26 (4.25)
4.72 (4.74)
5.23 (5.21)
5.28 (5.21)
4.05 (4.04)
4.03 (4.05)
4.49 (4.48)
4.46 (4.48)
3.54 (3.53)
5g
5h
5i
6a
6b
6c
6d
7a
7b
7c
7d

Syntheses and Antimicrobial Activity
1701
Table 2. Infrared spectral data of compounds 5a–i, 6a–d, and
7a–d
Compd.
P55O
P-C(aliphatic)
P55S
P55Se
5a
5b
5c
5d
5e
5f
1221
1226
1231
1225
1232
1238
1236
1227
1245
—
750
752
756
753
753
746
752
750
747
734
736
739
729
710
712
714
717
774
776
750
769
—
—
—
—
—
521
519
527
513
—
—
—
5g
5h
5i
—
—
6a
6b
6c
6d
7a
7b
7c
7d
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
EXPERIMENTAL
The melting points were determined on a Mel-Temp apparatus and are uncor-
rected. Elemental analyses were performed by the Central Drug Research
Institute, Lucknow, India. All IR spectra were recorded as KBr pellets on a
1
Perkin-Elmer 1430 unit. H, 13C, and 31P NMR spectra were recorded on
1
AMX 400-MHz spectrometer, operating at 400 MHz for H, 100 MHz for
13C, and 161.9 MHz for 31P as solution in CDCl3. The chemical shifts were
referenced to TMS (1H amd 13C) and 85% H3PO4 (31P) in parts per million
(ppm), and J(Hz) are given in parentheses.
2,20-Biphenol was procured from Lancaster Chemical Company, Inc.,
USA, and used without further purification.
Preparation of Ethyl Magnesium Bromide (3b)
In a dry, 100-mL, three-necked, round-bottomed flask fitted with dropping
funnel, a reflux condenser with a calcium chloride tube, a nitrogen inlet,
and a thermometer, magnesium turnings (0.12 g, 0.005 mol) and 5 mL of
dry THF were placed. The reaction mixture was stirred, and 2 mL of ethyl
bromide (0.54 g, 0.005 mol) in 10 mL of dry THF was added at 10–1508C
for 10 min. When the reaction started, the temperature increased to 40–458C.

1702
P. Haranath et al.
Table 3. 1H NMR chemical shift data of some compounds 5a–i, 6a–d, and 7a–d
Compd.
Ar-H
C-10
1.13
C-20
C-30
C-40
5a
7.36–7.52
(m, 8H)
(s, 3H)
1.72–1.80
(m, 2H)
5b
5c
5d
5e
5f
7.24–7.63
(m, 8H)
1.12–1.21
(m, 3H)
6.88–7.48
(m, 8H)
2.25–2.40
(m, 2H)
1.30–1.50
(m, 5H)
6.72–7.66
(m, 8H)
1.6–2.13
(m, 1H)
1.23–1.43
(m, 6H)
7.26–7.49
(m, 8H)
2.73–2.90
(m, 2H)
1.53–1.31
(m, 2H)
1.12–1.29
(m, 2H)
0.87–0.90
(m, 3H)
7.18–7.61
(m, 8H)
5.72–5.86
(m, 1H)
5.23–5.32
(m, 2H)
5g
5h
5i
7.15–7.59
(m, 8H)
3.07–3.12
(m, 2H)
3.05
5.92–6.02
(m, 1H)
3.24
5.39–5.40
(m, 2H)
6.98–7.46
(m, 8H)
(m, 2H)
2.12–2.31
(m, 2H)
(m, 2H)
1.32–1.56
(m, 5H)
6.99–7.76
(m, 13H)
6.78–7.41
(m, 8H)
6b
6d
7b
7d
2.12–2.31
(m, 2H)
1.32–1.56
(m, 5H)
7.05–7.87
(m, 13H)
6.69–7.22
(m, 8H)
2.21–2.41
(m, 2H)
1.34–1.47
(m, 5H)
7.05–7.89
(m, 13H)
The mixture was cooled to room temperature, and stirring was continued until
the magnesium metal was dissolved.
Synthesis of 3-(Ethyl)1,5-dihydro-2,4,3-benzodioxaphosphepin-3-
oxide (5b)
To a cooled (08C) and stirred solution of 2,20-biphenol (1, 0.93 g, 0.005 mol)
and triethylamine (1.01 g, 0.01 mol) in 25 mL of dry toluene under N2 gas, a
solution of phosphorus tribromide (1.35 g, 0.005 mol) in 10 mL of dry toluene
was added over a period of 20 min. After completion of the addition, the temp-
erature of the reaction mixture was raised room temperature and stirred for 1 h
to form the intermediate phosphorobromodite (2). The progress of the reaction
was judged by thin-layer chromatography (TLC) analysis. The reaction
mixture was filtered under a nitrogen atmosphere to remove triethylamine
hydrobromide.

Table 4. 13C NMR chemical shift data of some compounds 5a–i, 6a–d, and 7a–d
C(20 & 6 )/
C(30& 50)/
Compd.
C(1/11) C(2/10)
C(3/9)
C(4/8)
C(12/13)
C(4a/7a)
C(10)
C(20)
C(30)
C(40)
5a
5b
5c
5d
5e
5f
128.9
129.4
129.0
—
126.5
128.6
127.7
127.4
127.5
128.0
128.3
129.9
129.8
129.8
129.3
128.9
130.6
—
121.2
121.6
121.3
122.0
121.4
120.0
—
128.1
128.6
—
145 (14.9)
146.8 (10.6)
146.8 (9.2)
145.0 (9.9)
142.1 (10.1)
13.8 (136.0)
27.6 (139.4)
28.4 (140.2)
26.8 (140.7)
34.6 (138.2)
—
—
—
—
—
7.1 (4.5)
26.1 (4.7)
16.7 (4.7)
34.6 (5.2)
123.4 (4.9)
36.5 (4.8)
126.4 (126.0)
126.54
16.15 (15.6)
16.0 (4.7)
22.6 (14.7)
116.2 (4.6)
134.2
—
—
127.9
127.6
128.4
127.5
124.12
130.2
130.2
128.6
128.4
129.5
132.4
131.1
131.6
—
130.8
—
12.9
—
143.0 (11.0) 123.4 (131.6)
5g
5i
142.8 (9.2)
147.9
148.6
36.5 (132.8)
133.48
131.4
—
130.12
133.2
133.3
128.9
128.5
128.3
128.5 (128.3)
128.3
128.1
122.0
122.4
122.5
6d
7d
148.5
131.7
126.54

1704
P. Haranath et al.
Table 5. 31P NMR spectral data (ppm) of compounds
4a–i, 5a–i, 6a–d, and 7a–d
Compd.
31P(III) NMR
31P(V) NMR
4a
4b
4c
4d
4e
4f
123.2
129.2
122.6
124.2
146.1
138.4
139.2
130.3
146.1
—
—
—
—
—
—
—
4g
4h
4i
—
—
—
5a
5B
5c
5d
5e
5f
1.29
1.47
—
—
1.35, 0.28
4.49, 0.88
3.17
—
—
—
—
4.38, 0.31
3.19, 0.84
2.31
5g
5h
5i
—
—
25.59
82.11
86.14
87.11
99.70
101.21
101.74
101.34
107.85
6a
6b
6c
6d
7a
7b
7c
7d
—
—
—
—
—
—
—
—
The Grignard reagent 3b was cooled to 158C, and phosphorobromodite
(2) was added to it over 15 min under nitrogen. After the addition, the
reaction mixture was brought to room temperature and stirred for 90 min.
The progress of the reaction was monitored by TLC (ethyl acetate–hexane)
Table 6. Mass spectral data of compounds 5i, 6d, and 7d
Compd.
M/z (% relative abundance)
5i
308 [100, (Mþ†)], 228 (32.7), 215 (15.9), 184 (28.0), 168 (50.5), 139
(31.8)
6d
7d
321 [3.2, (Mþ†), 228 (3.0), 215 (3.0), 184 (100), 168 (4.5), 139 (5.4)
372 [32.7, (Mþ†)], 232 (100), 228 (34.7), 215 (23.4), 168 (4.7), 139
(29.9)

Table 7. Antibacterial activity (ppm) of compounds 4a–i, 5a–i, 6a–d, and 7a–d
Zone of inhibition (%)
Escherichia coli
Staphylococcus aureus
Compd.
100
50
25
100
50
25
5a
5b
10
10
9
3
3
2
4
—
5
3
5
5
6
6
5
7
6
6
6
7
6
—
—
—
2
7
8
2
3
4
3
3
—
4
3
4
4
5
4
4
5
6
4
5
5
—
—
2
5c
5d
7
11
8
8
—
—
—
2
5e
—
2
8
5f
5g
10
9
6
—
—
3
9
5g
9
8
—
2
5i
6a
11
10
10
9
10
9
2
2
6b
6c
2
8
2
3
9
2
6d
7a
11
10
11
11
12
10
2
8
2
3
10
10
10
11
9
2
7b
7c
2
3
3
2
7d
Streptomycin
3
—
3
—

Table 8. Antifungal activity (ppm) of compounds 4a–i, 5a–i, 6a–d, and 7a–d
Zone of inhibition (%)
Aspergillus niger
Helminthosporium aryzae
Compd.
100
50
25
100
50
25
5a
13
11
11
14
11
13
16
16
17
17
19
19
20
21
20
20
21
18
6
6
5
7
6
6
7
6
7
7
6
7
6
7
6
7
9
8
3
2
2
3
3
4
3
2
3
4
3
3
3
4
3
3
4
4
12
14
14
12
14
12
15
14
15
16
15
16
17
18
17
17
18
16
6
5
6
5
6
5
5
6
6
7
6
7
7
8
8
7
9
7
2
2
5b
5c
2
5d
5e
—
—
2
5f
5g
2
5g
2
5i
6a
3
3
6b
6c
2
2
6d
7a
3
4
7b
7c
4
3
7d
Bavistin
4
3

Syntheses and Antimicrobial Activity
1707
analysis. After completion of the reaction, the mixture was cooled to 58C and
then hydrolyzed by slow addition of saturated aqueous NH4Cl solution with
cooling. The solvent was removed under vacuum, and the residue was
extracted with ethyl acetate. The extract, after washing with brine solution
and drying over anhydrous MgSO4, was evaporated in a rotaevaporator. The
obtained crude product (4b) was dissolved in dichloromethane (30 mL), and
hydrogen peroxide (30% H2O2, 0.2 mL, 0.005 mol) was added to it
dropwise at 0–58C. The reaction mixture was brought to room temperature
and kept stirring for 2 h for the completion of oxidation as indicated by
TLC analysis. The reaction mixture was washed with saturated NaCl
solution and dried over anhydrous MgSO4, and the solvent was removed in
a rotaevaporator. The resulting crude product was recrystallized from
2-propanol to yield 1.46 g (76%) of 5b, mp 119–1208C.
Synthesis of 6-Phenyl-dibenzo[d, f ][1,3,2]dioxaphosphepin-6-
sulfide/selenide (6d/7d)
The Grignard reagent 3i was cooled to 158C, and phosphorobromodite (2) was
added to it over 15 minutes under nitrogen. After the addition, the reaction
mixture was brought to room temperature and stirred for 90 min. The
progress of the reaction was monitored by TLC analysis (ethyl acetate–
hexane in 1:1) of the reactive mixture. After completion of the reaction, the
mixture was cooled to 58C, sulfur powder/selenium metal was added. It
was heated slowly up to gentle reflux with stirring for 2 h for the completion
of the reaction as indicated by TLC analysis. The solvent was removed under
vacuum, and the residue was extracted with ethyl acetate. After washing with
brine solution and drying over anhydrous MgSO4, the extract was evaporated
in a rotaevaporator. The crude product (6d/7d) obtained was recrystallized
from 2-propanol to yield 6d/7d.
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1. (a) Baylis, E. K.; Campbell, C. D.; Dingwall, J. G. J. Chem. Soc., Perkin Trans. 1,
1984, 2845; (b) Demir, A. S.; Tanyeli, C.; Sesenoglu, O.; Demic, S.; Evin, O. O.
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