Oxidation of bisnaphthols to spironaphthalenones, revisited

Article abstract of DOI:10.1002/jhet.5570450516

(Chemical Equation Presented) Bis(2-hydroxy-1-naphthyl)methane derivatives have been efficiently converted to their corresponding spirans through three methods, i.e. oxidation by TCCA under mild reaction conditions, Ph₃Bi catalyzed air oxidatio

Full text of DOI:10.1002/jhet.5570450516

Sep-Oct 2008
1351
Oxidation of Bisnaphthols to Spironaphthalenones, Revisited
Ahmad Khoramabadi-zad*, Isaa Yavari, Azam Shiri and Azad Bani
Chem. Dept.; Bu-Ali Sina Univ.; Hamadan 65174; Iran
khoram@gmail.com
Received November 13, 2007
O
O
OH
H(X)
oxidation
OH
(H)X
X= H, Ar
Bis(2-hydroxy-1-naphthyl)methane derivatives have been efficiently converted to their corresponding
spirans through three methods, i.e. oxidation by TCCA under mild reaction conditions, Ph3Bi catalyzed air
oxidation, and by electrochemical reaction. The first two methods are diastereoselective and give either of
the two possible diastereomers, while the electrochemical method produces equal amounts of these
diastereomers.
J. Heterocyclic Chem., 45, 1351 (2008).
INTRODUCTION
According to Kasturi’s reports, Abel ketone derivatives
have two sets of diastereomers 3 and 4; the stereoisomer 4
is formed when steric hindrance is the decisive factor. By
their procedure, the use of more than one molar
equivalent of persulphate or freshly prepared solution of
potassium hypobromite (from bromine in 10% Aq. KOH
The mild alkaline oxidation of bisnaphthols was
reported by Abel in 1892 [1]. The product was believed to
be a peroxide, but on the basis of chemical evidence the
spirodienone structure 2 was later reassigned to it [2,3].
at
0 ºC) gives 3, whereas iodine oxyacids and
6
(diacetoxyiodo) benzene are specific for the preparation
of 4 in refluxing benzene. Radical type oxidants such as
hexacyanoferrate (III) (in benzene and pyridine) and 2,4-
di-t-butyl-6-phenylphenoxyl give mixtures of 3 and 4
[13,20]. The two diastereomers are distinguished by the
5
4
OH
Br2
3
1
O
2
Alkaline
1
OH
O
fact that isomers of series 3 show in their H NMR a
1'
doublet near ꢀ 6.1 ppm (vinylic H-3'); while for isomers
of series 4, this hydrogen appears at about ꢀ 5.4 ppm; the
up-field shift being due to the shielding effect of the
phenyl ring [13].
3'
5'
4'
1
2
O
O
The spirodienone derivatives of substituted and
unsubstituted bis(naphthol)methanes have been the
subject of numerous studies and remain one of the most
thoroughly studied members of the spirodienone family
[4-17]. The Abel’s ketone 2 was also prepared by
oxidizing 1 with NaBiO3 in refluxing benzene in 3 hours
[18].
R
3'
3
4
O
O
H
5
D
E
D
E
2
B
4'
5'
1'
H
B
A
A
1
9
R
3
4
Oxidation of bis(2-hydroxy-1-naphthyl)methane 1 with
o-chloranil [tetrachloro-o-benzoquinone] was studied by
Kasturi and coworkers in 1979 who obtained five
products [19]. The reaction of the substituted bisnaphthols
with DDQ has been also carried out in refluxing dry
benzene yielding the corresponding spiro compounds
along with dimerized products [5].
As is evident from the above mentioned examples, the
oxidizing agents and/or solvents are toxic, and
carcinogenic (like benzene). Therefore, following the
general trend toward green chemistry, we now report
three ways for the oxidation of bisnaphthols which are
presented in three parts. In part 1, the diastereomers of

1352
A. Khoramabadi-zad, I. Yavari, A. Shiri and A. Bani
Vol 45
Abel’s ketones are fairly known compounds) shows that
the chemical shift of H-3' of all substituted products
appears at 6.2-6.3 ppm, which is a proof for the formation
of diastereomers series 3. To account for such a
diastereoselectivity a plausible reaction mechanism is
shown in Chart 1.
series 3 are formed by the action of TCCA in acetone
solution. In part 2, the catalytic action of Ph3Bi on air-
oxidation of bisnaphthols is presented. And finally, it is
shown that electro-oxidation of bisnaphthols gives a 1:1
mixture of the two diastereomeric seris 3 and 4.
Part 1. Oxidation of bisnaphthols by TCCA. This
part describes the efficient diastereoselective oxidation of
bisnaphthols to 3, under mild reaction conditions (in
acetone without adding any catalyst) using less than one
molar equivalent of TCCA [1,3,5-trichloro-1,3,5-triazin-
2,4,6-(1H,3H,5H)-trione] (Scheme 1). Notably TCCA is a
relatively stable and very cheap reagent that has been used
synthetically in oxidation and chlorination of various
types of compounds [21,22]. (In many reported methods
TCCA has been used with combination of different
catalysts e.g. RuCl3 and Tempo for oxidation reaction or
using metal halide such as NaBr [23,24].)
Chart 1
O
O
Cl
O
Cl
O
HN
NH
N
N
+ H2O
+ HOCl
O
N
H
O
N
Cl
OH -
+
Cl+
HOCl
H
H
Ar
Ar
- 2H+, Cl+
Scheme 1
Cl
O
OH HO
O
O
-
Cl
Cl
N
N
O
O
H
O
N
O
H
H
Ar
Ar
OH
OH
Cl
swivel
X
H
Cl
Cl
acetone, aq NaHCO3,
r.t.
X
-
O-
O
O
O
-Cl-
2, X= H
1, X= H
3a, X= C6H4
1a, X= C6H4
3
3b, X=4-CH3C6H4
3c, X= 3-CH3C6H4
3d, X= 4-ClC6H4
3e, X= 2-ClC6H4
3f, X= 4-BrC6H4
3g, X= 3-BrC6H4
3h, X= 4-CH3OC6H4
1b, X=4-CH3C6H4
1c, X= 3-CH3C6H4
1d, X= 4-ClC6H4
1e, X= 2-ClC6H4
1f, X= 4-BrC6H4
1g, X= 3-BrC6H4
1h, X= 4-CH3OC6H4
The reaction is reasonably fast, and only in one case,
i.e. entry 1, it requires 1.5 h for completion. During the
reaction, TCCA is converted into cyanuric acid (CAN)
with the generation of HCl, which is neutralized with an
acid scavenger such as pyridine, K2CO3, NaOH and
NaHCO3 [25,26]. In the present oxidation reaction,
aqueous NaHCO3 solution was used for the reaction to
proceed under mild conditions with very good to excellent
yields.
Our general procedure is based on the addition of
TCCA/acetone solution to a slightly alkaline aqueous
acetone solution of bisnaphthols at room temperature
without any catalyst or metal halide. The conversion of all
tested substrates is 100% and the oxidation reaction is
practically quantitative (Table 1).
Part 2. Ph3Bi catalyzed air-oxidation of bisnaphthols
under microwave irradiation. Postel and Duñach in a
review have mentioned the catalytic activity of Bi(III)
compounds, such as triphenylbismuth and Bismuth(III)
mandalate, in certain oxidation reactions [27]. Therefore
we concluded that Ph3Bi might be a good catalyst for the
oxidation of bis(naphthol)methanes in the presence of
oxygen. Following these lines and considering the low
toxicity of bismuth compounds we report the synthesis of
Abel’s ketone and its derivatives by air oxidation of the
corresponding bis(naphthol)methanes 1, 1a-b, 1d-e and
1h in the presence of a catalytic amount of Ph3Bi [10
mol%] (Scheme 2). This reaction may be carried out
under microwave irradiation without the need of alkaline
medium. Appearance of hydrogen number 3' of all
Table 1: Reaction time, yield and melting point of products
shown in Scheme 1.
Entry
Product
2
3a
Time (min) Yield (%)
M.P. (Lit) ºC
170-171 (168-169) 1
210-211
198-200
187-188
262-263
259-260
214-216
1
2
3
4
5
6
7
8
9
1.5 h
30
10
10
5
30
4
3
85
87
84
83
95
81
81
79
92
3b
3c
3d
3e
3f
3g
3h
204-205
199-200 (195-197) 12
5
Inspection of spectral data (which we will focus,
throughout this paper merely on H NMR spectra because
1

Sep-Oct 2008
Oxidation of Bisnaphthols to Spironaphthalenones
1353
products at 5.2-5.5 ppm range in the 1H NMR spectra is a
proof for the formation of diastereoisomer series 4.
Scheme 2
O
O
X
OH
OH
MW, Air
X
Ph3Bi
10 mol%
H
2, X=H
1, X= H
4a, X=C6H5
1a, X=C6H5
4b, X=4-CH3C6H4
4d, X=4-ClC6H4
4e, X=2-ClC6H4
4h, X=4-CH3OC6H4
1b, X=4-CH3C6H4
1d, X=4-ClC6H4
1e, X=2-ClC6H4
1h, X=4-CH3OC6H4
Figure 1: Stereo-view of peroxide intermediate
Table 2: Reaction time, crude yield and melting point of
products shown in Scheme 2
is the highly preferred one because there is much less
steric hindrance between the starred ring and the μ-phenyl
ring. In that conformation, only the peroxydic oxygen the
further away form the μ-phenyl ring has the proper
orientation to form the spiro diastereoisomer 4a.
Entry Product Time (min) Yield (%) M.P. (Lit) ºC
1
2
3
4
5
6
2
12
14
10
15
5
98
85
68
70
72
83
170-171 (168-169) 1
4a
4b
4d
4e
4h
263-264
227-229
To prove the identity of the reaction product, we have
succeeded in preparing single crystals for one of the
compounds (4h) and fully characterized its structure by
X-ray. Figure 2 shows the shape and Tables 3 and 4
present selected internal parameters of the compound 4h.
262-263
259-260
217-220 (227-229) 1
14
It should be mentioned that, when acetone solutions of
halo-compounds such as 1d and 1e stand for a relatively
long time, they are oxidized to 4d and 4e respectively.
Therefore, it seems that these two processes, i.e. sluggish
oxidation of halo-compounds in acetone solution and
relatively fast Ph3Bi catalyzed oxidation of all
bisnaphthols may have the same peroxide intermediate 5.
The stereo-view of such an intermediate (from AM1
calculations) for the oxidation of 1a to 4a is presented
below (see Figure 1).
O
Ar
O
Figure 2: X-ray (ORTEP) of compound 4h.
5
Part 3. Electro-oxidation of bisnaphthols. Cyclic
voltammograms of bisnaphthols (1.0 mM) in a solution
containing sodium hydrogen carbonate buffer (0.20 M, pH
8.3), show an anodic peak at 0.38-0.52 V but no
corresponding cathodic peak even at a scan rate of 1000
Inspection of this molecular model reveals that, of the
two conformations which would allow the attack of one or
the other oxygen on the phenyl ring to form the five-
membered heterocyle, the conformation shown in Figure 1

1354
A. Khoramabadi-zad, I. Yavari, A. Shiri and A. Bani
Vol 45
Table 3: Selected bond lengths (Å) for compound 4h
O(1)-C(28)
O(1)-C(10)
O(2)-C(1)
1.3675(13)
1.4439(13)
1.2190(14)
C(1)-C(2)
C(1)-C(10)
C(2)-C(3)
1.4630(16)
1.5284(15)
1.3408(17)
C(3)-C(4)
1.4625(16)
1.5120(15)
1.6146(15)
C(11)-C(19)
C(19)-C(28)
1.5107(14)
1.3655(15)
C(9)-C(10)
C(10)-C(11)
Table 4: Selected bond angles (degree) of compound 4h
C(28)-O(1)-C(10) 108.18(8)
C(9)-C(10)-C(1)
123.01(10) O(1)-C(10)-C(11)
116.41(9) C(1)-C(10)-C(11)
113.04(9)
106.65(8)
109.54(8)
C(28)-C(19)-C(11)
109.97(9)
130.22(10)
114.50(9)
121.72(10)
O(2)-C(1)-C(2)
C(2)-C(1)-C(10)
C(3)-C(2)-C(1)
O(1)-C(10)-C(9)
O(1)-C(10)-C(1)
C(20)-C(19)-C(11)
C(19)-C(28)-O(1)
O(1)-C(28)-C(27)
120.60(10) C(19)-C(11)-C(12) 115.52(9)
109.37(8)
108.09(8)
C(19)-C(11)-C(10) 99.73(8)
C(12)-C(11)-C(10) 115.45(8)
mVs-1 (see Figures 3 and 4). Therefore, the oxidation is
irreversible due to the rapid follow up chemical reactions
as discussed below in presenting the results of preparative
oxidation. [Controlled potential coulometry also
performed in a divided cell under the above conditions].
Figure 4. Typical cyclic voltammograms of 1mM p-methylbisnaphthol
(1b) in 50:50 water/acetonitrile solution at various scan rates. Scan
rates from (1) to (6) are: 100, 200, 300, 400, 500, and 1000 mVsꢀ1
respectively, at a glassy carbon electrode (1.8 mm diameter) in solution
,
containing 0.20 M carbonate buffer (pH 8.3). t=25±1 ºC.
Table 5: Reaction time and crude yields of electro-oxidation products
Entry
Product
Time (h)
Yield (%)
1
2
3
4
5
2
22.58
22.58
23
83
90
3a-4a
3b-4b
3c-4c
3h-4h
75
92
16
21.88
94.5
Figure 3. voltamogram of p-methoxybisnaphthol 1h at a glassy carbon
electrode (1.8mm diameter) in solution containing 0.20 M carbonate
buffer (pH 8.3). Scan rate: 20 mVs-1; t=25±1 ºC.
Calculations, based on consumed coulombs, reveals
that in electro-oxidation reaction two electrons are
exchanged. The formation of a diradical by a two-electron
oxidation is rejected because it may lead to the peroxide
intermediate mentioned in Part 2, which will be in favor
of diastereomers of series 4. Therefore, to account for the
formation of a 1:1 ratio of distereomeres 3 and 4, an ECE
mechanism is proposed (Chart 2). The first step, after
deprotonation reaction at pH 8.3, is an electro-oxidation
reaction (electron transfer, E). This step is followed by
The yields, the quantity of coulombs passed, and the
required time for the electro-oxidation of bisnaphthols 1a,
1b, 1c, and 1h are presented in Table 5. There are no data
for chloro- and bromosubstituted bisnaphthols 1d, 1e, and
1f. This is because these compounds are air-oxidized to
their corresponding diastereoisomers 4d, 4e and 4f.
Therefore, the diastereomeric ratio would not be
representative of that of the electro-oxidation.

Sep-Oct 2008
Oxidation of Bisnaphthols to Spironaphthalenones
1355
two chemical reactions (C), i.e. deprotonation and
cyclization. As there is no preference for the cyclization
reaction, it will lead to the formation of the two
diastereomers in a 1:1 ratio. The final step (E) is a fast
one-electron oxidation of the radical anion.
CONCLUSION
The oxidation of each substituted bisnaphthol by TCCA
gives only one product the 3'H of which appears (in the
1H NMR spectrum) at about ꢀ 6.2 ppm. In this case
Chart 2
Electron transfer (E):
.
.
O
O
O
-e
Ar
H
Ar
H
Ar
H
OH
OH
OH
-H+
Chemical reaction (C):
(Deprotonation)
.
O
O
Ar
H
(Cyclization)
O
O
Ar
H
Ar
O
O
Electron transfer (E):
O
O
-e
Ar
Ar
O
O

1356
A. Khoramabadi-zad, I. Yavari, A. Shiri and A. Bani
Vol 45
TLC). The mixture was then filtered and concentrated under
vacuum. The aqueous phase was washed with portions of
AcOEt, treated with 1 N HCl, and extracted twice with AcOEt.
The organic layer was dried over Na2SO4 and the solvent
evaporated to yield the product. Further purification was carried
out by crystallization in acetone/n-hexane.
therefore, the diastereomer 3 is formed. On the other
hand, when the same bisnaphthols are oxidized in the
presence triphenylbismuth (10 mol %), the above said
hydrogen appears now at about ꢀ 5.2 ppm, which is
representative of diastereomer series 4. However, the
electro-oxidation of bisnaphthols shows, for each
Ph3Bi catalyzed air oxidation under microwave
irradiation. The corresponding bisnaphthol (0.3 mMol) and
triphenylbismuth (10 mol %) were mixed thoroughly and
subjected to microwave irradiation under combin1 mode (20%
microwave and 80% grill) for 10-14 min. in solvent free
conditions. This mode was chosen to fuse the starting materials
by preheating the mixture. CHCl3 (5-10 mL) was added to the
cooled product and the mixture was filtered. The main products
were separated by column chromatography using silica gel as
stationary phase and a mixture of acetone/n-hexane as eluent.
Electro-oxidation of bisnaphthols. A solution of sodium
hydrogen carbonate buffer (40 mL) (c = 0.20 M, pH 8.3) in
water mixed with a solution of acetonitrile (40 mL) containing
bisnaphthols (1 mMol), was electro-oxidized in an undivided
cell equipped with a graphite anode (an assembly of four rods, 6
mm diameter and 4 cm length) and a graphite cathode with 1 cm
diameter at 40°C under constant-potential of 0.4-0.5 V. The
1
corresponding H NMR spectrum of the product, a set of
two doublets at about ꢀ 6.2 ppm and ꢀ 5.5 ppm. The 1:1
integral ratio of these two hydrogens is a good evidence
of the non-selectivity of electro-oxidation reaction.
In conclusion, we have run the oxidation of
bisnaphthols by using TCCA, air, or electricity. In the
first case, the reaction conditions are mild, safe, and the
separation procedure is easy to perform. In the second
case, the reaction proceeds under environmental friendly
and solvent free conditions: microwave irradiation of the
molten reactants mixture and use of a relatively benign
catalyst, Ph3Bi. The last method of oxidation, i.e. electro-
oxidation reaction, is both safe and clean. From the point
of view of green chemistry, use of the electrosynthesis
method has some important advantages. Clean synthesis,
use of electricity as energy instead of oxidative reagents,
use of aqueous/organic media instead of organic solvents,
one-step room temperature reaction and, technical
feasibility are among the advantages to be mentioned.
quantity of the electricity passed was determined by
a
potentiostat. The process was interrupted during the electro-
oxidation, and the graphite anode was washed in acetone in
order to reactivate it. At the end of reaction and evaporation of
acetonitrile, the solution was extracted by AcOEt, and dried over
magnesium sulfate. In order to eliminate any by-product, a
chromatographic step was performed and the spiran fractions re-
combined for further analysis by 1H NMR spectroscopy.
(Because Abel’s ketones are well known compounds only their
NMR data are presented below)
EXPERIMENTAL
All solvents and reagents were used as obtained from Merk
(except that of TCCA which was purchased from Fluka). The
methylenbisnaphthol 1 was prepared according to the Mironov
method and the other substrates, 1a-1h, by the procedure of
Hewitt and Tunner [28-29]. Standard NMR spectra were
obtained on a Brüker 500 MHz (and/or Jeol 90 MHz)
spectrometers, respectively in CDCl3 as solvent. Melting points
were determined by electrothermal melting point apparatus
without further correction. The source of microwave radiation
was the LG domestic microwave oven (model MG-583MC). In
electro-oxidation experiments an auto lab potentiostat/
galvanostat (Model BHP2050, by Behpajooh Co., Iran) was
used. The working electrode was an assembly of four graphite
rods (6mm diameter and 4 cm length) and a graphite rod
constituted the counter electrode. The working electrode
potentials were measured versus SCE (all electrodes were
purchased from AZAR ELECTRODE, Iran).
Spiro{naphthalene-1(2H),2'(1'H)-naphtho[2,1-b]fur-an}-2-
1
one. (Abel’s ketone 2); selected H NMR (CDCl3, TMS): ꢀ3.50
(1H, d, J=15.6 Hz); ꢀ4.06 (1H, d J=15.6 Hz); ꢀ6.24 (1H, d,
J=10.0 Hz due to hydrogen number 3'); ꢀ 7.24-7.88 (11H,
aromatic and hydrogen number 4').
1'-Phenyl-spiro{naphthalene-1(2H),2'(1'H)-naphtho-[2,1-b]-
furan}-2-one (3a). 1H NMR (CDCl3, TMS): ꢀ5.39 (1H, s,
hydrogen number 1), ꢀ6.27 (1H, d, J=10.0 Hz due to hydrogen
number 3'), ꢀ6.93-7.94 (16H, aromatic and hydrogen number 4').
1'-(4-Methylphenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3b). 1H NMR (CDCl3, TMS):
ꢀ2.12 (3H, s), ꢀ5.36 (1H, s, hydrogen number 1), ꢀ6.26 (1H, d,
J=9.9 Hz due to hydrogen number 3'), ꢀ6.67-7.93 (15H,
aromatic and hydrogen number 4').
1'-(3-Methylphenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3c). 1H NMR (CDCl3, TMS):
ꢀ2.01 (3H, s), ꢀ5.34 (1H, s, hydrogen number 1), ꢀ6.25 (1H, d,
J=9.90 Hz due to hydrogen number 3'), ꢀ6.75-7.93 (15H,
aromatic and hydrogen number 4').
1'-(4-Chlorophenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3d). 1H NMR (CDCl3, TMS):
ꢀ5.36 (1H, s, hydrogen number 1); ꢀ6.26 (1H, d, J=9.90 Hz due
to hydrogen number 3'); ꢀ6.86-7.94 (15H, aromatic and
hydrogen number 4').
1'-(2-Chlorophenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3e). 1H NMR (CDCl3, TMS):
ꢀ6.00(1H, s, hydrogen number 1); ꢀ6.23 (1H, d, J=10.0 Hz due
to hydrogen number 3'); ꢀ6.52-7.84 (15H, aromatic and
hydrogen number 4').
General Procedures.
Oxidation by TCCA. The procedure for the oxidation of 4-
methylbisnaphthol (entry 3 Table 1) is representative for all
cases. An aqueous 15% solution of NaHCO3 (3 mL) was added
to the bisnaphthol (0.0406 g, 0.1 mMol) in acetone (10 mL),
stirred and maintained at 0 ºC; TCCA (0.0176 g, 0.075 mMol) in
acetone (2 mL) was then slowly added within 15 min (When it
was added at once, side products were formed and no attempt
was made to identify them) at 0 ºC. The color of the white
suspension rapidly changes to yellow. After addition of TCCA
solution, the mixture was warmed to room temperature and
stirred for the required time until completion (monitored by

Sep-Oct 2008
Oxidation of Bisnaphthols to Spironaphthalenones
1357
1'-(4-Bromophenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3f). 1H NMR (CDCl3, TMS):
ꢀ5.34 (1H, s, hydrogen number 1); ꢀ6.26 (1H, d, J=10.0 Hz due
to hydrogen number 3'); ꢀ7.00-7.94 (15H, aromatic and
hydrogen number 4').
1'-(3-Bromophenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3g). 1H NMR (CDCl3, TMS):
ꢀ5.32 (1H, s, hydrogen number 1); ꢀ6.27 (1H, d, J=10.0 Hz due
to hydrogen number 3'); ꢀ7.09-7.96 (15H, aromatic and
hydrogen number 4').
1'-(4-Methoxyphenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3h). 1H NMR (CDCl3, TMS):
ꢀ3.62 (3H, s), ꢀ5.35 (1H, s, hydrogen number 1), ꢀ6.25 (1H, d,
J=10.0 Hz due to hydrogen number 3'), ꢀ6.41-7.93 (15H,
aromatic and hydrogen number 4').
1HNMR Spectral data for Ph3Bi catalyzed air oxidation
under microwave irradiation.
methyl hydrogens], [ꢀ5.15 (s, 1H), ꢀ 5.33 (s, 1H) two kinds of
hydrogen number 1], [ꢀ5.51 (d, 1H d, J=9.90 Hz), ꢀ6.23 (d, 1H
d, J=9.99 Hz two kinds of hydrogen number 3')], ꢀ6.74-7.91
(aromatic and hydrogen number 4').
1'-(4-Methoxyphenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3h and 4h). 1H NMR (CDCl3,
TMS): [ꢀ3.61(3H, s), ꢀ3.72 (3H, s), two kinds of methoxy
hydrogens], [ꢀ5.17 (s, 1H), ꢀ 5.35 (s, 1H) two kinds of hydrogen
number 1], [ꢀ5.55 (d, 1H d, J=10.3 Hz), ꢀ6.24 (d, 1H d, J=10.2
Hz two kinds of hydrogen number 3')], ꢀ6.39-7.92 (aromatic and
hydrogen number 4').
Acknowledgement. We would like to acknowledge our
colleagues, Prof. Bernhard K. Keppler, Vladimir Arion and Dr.
Christian Hartinger, for the X-ray crystallography and very
precious comments on the original manuscripts. The authors
gratefully acknowledge the financial supports from the Bu Ali
Sina University, Hamadan 6517838683, Iran.
Spiro{naphthalene-1(2H),2'(1'H)-naphtho[2,1-b]furan}-2-
1
one. (Abel’s ketone 2); selected H NMR (CDCl3, TMS): ꢀ3.50
REFERENCES
(1H, d, J=15.6 Hz); ꢀ4.06 (1H, d J=15.6 Hz); ꢀ6.24 (1H, d,
J=9.99 Hz).
[1] Abel, J. Chem. Ber. 1892, 25, 3477.
1'-Phenyl-spiro{naphthalene-1(2H),2'(1'H)-naphtho-[2,1-b]-
furan}-2-one (4a). 1H NMR (CDCl3, TMS): ꢀ5.22 (1H, s,
hydrogen number 1), ꢀ5.54 (1H, d, J=9.99 Hz due to hydrogen
number 3'), ꢀ7.01-7.92 (16H, aromatic and hydrogen number 4').
1'-(4-Methylphenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (4b). 1H NMR (CDCl3, TMS):
ꢀ1.74 (3H, s), ꢀ5.16 (1H, s, hydrogen number 1), ꢀ5.55 (1H, d,
J=9.81 Hz due to hydrogen number 3'), ꢀ6.87-7.93 (15H,
aromatic and hydrogen number 4').
[2] Pummerer, R.; Cherbuliez, E. Chem. Ber. 1914, 47, 2957.
[3] Shearing, E. A.; Smiles, S. J. Chem. Soc. 1937, 1931.
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Sivaramakrishnan, R.; Ramasubbu, N.; Venkatesan, K. J. Chem. Soc.,
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[6] Ward, R. S. Chem. Brit. 1973, 9, 444.
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Jayaram, S. K.; Singh, S. B.; Tetrahedron 1992, 48, 5481.
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1'-(4-Chlorophenyl)-spiro{naphthalene-1(2H),2'(1'H)-
1
naphtho[2,1-b]furan}-2-one (4d). Selected H NMR (CDCl3,
TMS): ꢀ5.17 (1H, s, hydrogen number 1); ꢀ5.57 (1H, d, J=10.2
Hz due to hydrogen number 3'); ꢀ6.88-7.95 (15H, aromatic and
hydrogen number 4').
[10] Dean, F. M.; Locksley, H. D. J. Chem. Soc. 1963, 393.
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1976, 1557.
[12] Bennett, D. J.; Dean, F. M.; Herbin, G. A.; Martin, D. A.;
Price, A. W.; Robinsin, M. L. J. Chem. Soc., Perkin Trans. I 1980, 1978.
[13] Dean, F. M.; Herbin, G. A.; Martin, D. A.; Price, A. W.;
Robinsin, M. L.; J. Chem. Soc., Perkin Trans. I 1980, 1986.
[14] Kasturi, T. R.; Tayaram, S. K.; Pragnacharyulu, P. V. P.;
Sattigeri, J. A.; Reddy, G. M.; Kumar, K. A.; Tetrahedron 1993, 49, 113.
[15] Kasturi, T. R.; Kumar, K. A.; Pragnacharyulu, P. V. P.;
Tetrahedron 1993, 49, 125.
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Sridevi, G. Tetrahedron 1993, 49, 135.
[17] Kasturi, T. R.; Sattigeri, J. A.; Pragnacharyulu, P. V. P.
Tetrahedron 1995, 51, 3051.
1'-(2-Chlorophenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (4e). selected 1H NMR (CDCl3,
TMS): ꢀ5.86 (1H, s, hydrogen number 1); ꢀ5.50 (1H, d, J=10.3
Hz due to hydrogen number 3'); ꢀ6.66-7.92 (15H, aromatic and
hydrogen number 4').
1'-(4-Methoxyphenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (4h). 1H NMR (CDCl3, TMS):
ꢀ3.75 (3H, s), ꢀ5.20 (1H, s, hydrogen number 1), ꢀ5.58 (1H, d,
J=9.99 Hz due to hydrogen number 3'), ꢀ6.72-7.91 (15H,
aromatic and hydrogen number 4').
1HNMR spectral data for electro-oxidation reaction.
[18] Hewitt, D. J. J. Chem. Soc(C). 1971, 1750.
[19] Kasturi, T. R.; Rajasekhar, B.; Siraramakrishnan, R. Indian J.
Chem., Sect. B, 1979, 18, 1.
1'-Phenyl-spiro{naphthalene-1(2H),2'(1'H)-naphtho-[2,1-b]-
1
furan}-2-one (3a and 4a). H NMR (CDCl3, TMS): [ꢀ5.20 (s,
1H), ꢀ 5.39 (s, 1H) two kinds of hydrogen number 1], [ꢀ5.51 (d,
1H d, J=9.90 Hz), ꢀ6.26 (d, 1H d, J=9.90 Hz two kinds of
hydrogen number 3')], ꢀ6.94-7.93 (aromatic and hydrogen
number 4').
1'-(4-Methylphenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3b and 4b). 1H NMR (CDCl3,
TMS): [ꢀ2.08 (3H, s), ꢀ2.23 (3H, s), two kinds of methyl
hydrogens], [ꢀ5.17 (s, 1H), ꢀ 5.36 (s, 1H) two kinds of hydrogen
number 1], [ꢀ5.51 (d, 1H d, J=9.90 Hz), ꢀ6.22 (d, 1H d, J=9.90
Hz two kinds of hydrogen number 3')], ꢀ6.66-7.90 (aromatic and
hydrogen number 4').
[20] Bennett, D. J.; Dean, F. M.; Herbin, G. A.; Matkin, D. A.;
Price, A. W.; Robinson, M. L. J. Chem. Soc., Perkin Trans. I 1980,
1978.
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385, and references cited there in; [b] Back, T. G.; Chav, J. H-L.; Duck,
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1'-(3-Methylphenyl)-spiro{naphthalene-1(2H),2'(1'H)-
naphtho[2,1-b]furan}-2-one (3c and 4c). mp: =188-190. 1H
NMR (CDCl3, TMS): [ꢀ2.00 (3H, s), ꢀ2.17 (3H, s), two kinds of

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Vol 45
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