A practical synthesis and estrogenic activity of 5-hydroxy-1-(4′- hydroxyphenyl)-1,3,3-trimethylindan, a contaminant in industrial grade bisphenol A

Article abstract of DOI:10.1246/cl.2005.188

A practical synthesis of 5-hydroxy-1-(4′-hydroxyphenyl)-1,3,3- trimethylindan was achieved from α-methylstyrene. The starting compound was dimerized in the presence of trifluoroacetic acid to produce 1-phenyl-1,3,3-trimethylindan. Aromatic nitration of the phenylindane was carried out using a mixture of nitric acid and acetic anhydride. The nitro group was then converted to hydroxyl via reduction and a diazonium salt sequence to form 5-hydroxy-1-(4′-hydroxyphenyl)-1,3,3-trimethylindan. The estrogenicity of the product was 8.7 times that of BPA. Our finding has demonstrated the endocrine-disrupting properties of the product. Copyright

Full text of DOI:10.1246/cl.2005.188

188
Chemistry Letters Vol.34, No.2 (2005)
A Practical Synthesis and Estrogenic Activity of 5-Hydroxy-1-(40-hydroxyphenyl)-1,3,3-
trimethylindan, a Contaminant in Industrial Grade Bisphenol A
Masanori Terasaki,ꢀ Fujio Shiraishi,y Tomohiro Nishikawa,y Masatoshi Morita,y and Masakazu Makino
Institute for Environmental Sciences, University of Shizuoka, 52-1 Yada, 422-8526
yEndocrine Disrupter Research Laboratory, National Institute for Environmental Studies,
16-2 Onogawa, Tsukuba 305-8506
(Received November 8, 2004; CL-041333)
A practical synthesis of 5-hydroxy-1-(40-hydroxyphenyl)-
methylindan: In the synthetic path illustrated in Scheme 1, we
selected all reagents and solvents volatile enough to be easily
evaporated, except for the filtration required for the separation
of Pd/C in the third step, in order to attain a facile synthesis.
ꢀ-Methylstyrene (3) (10 mL) was added dropwise to trifluoro-
acetic acid (TFA) (30 mL) and the mixture, which rapidly turned
red, was stirred for 12 h at room temperature. The reaction mix-
ture was evaporated to dryness under reduced pressure. 1H,
13C NMR, and high resolution (HR) FAB MS examination of
the residue showed 1-phenyl-1,3,3-trimethylindan (4), a dimer
of ꢀ-methylstyrene.6
1,3,3-trimethylindan was achieved from ꢀ-methylstyrene. The
starting compound was dimerized in the presence of trifluoroace-
tic acid to produce 1-phenyl-1,3,3-trimethylindan. Aromatic
nitration of the phenylindane was carried out using a mixture
of nitric acid and acetic anhydride. The nitro group was then
converted to hydroxyl via reduction and a diazonium salt
sequence to form 5-hydroxy-1-(40-hydroxyphenyl)-1,3,3-tri-
methylindan. The estrogenicity of the product was 8.7 times that
of BPA. Our finding has demonstrated the endocrine-disrupting
properties of the product.
The key step was the substitution reaction of phenylindan
(4), which introduced two nitro groups at the required positions
on the benzene ring. Although formation of the desired dinitro
compound, 5-nitro-1-(40-nitrophenyl)-1,3,3-trimethylindan (5),
is sterically disadvantageous, nitration gave an appreciable
amount of 5. Thus, to the reaction product containing 4 in
chloroform (20 mL), a previously mixed solution of nitric acid
(3.3 mL) and acetic anhydride (22.5 mL) was added dropwise
at 0 ꢁC. The reaction temperature was maintained for an addi-
tional 2 h. The product was revealed to contain dinitroindans 5
Bisphenol A (4,40-isopropylidenediphenol, BPA; CAS No.
80-05-7) (Chart 1) is used as a monomer in the manufacture of
polycarbonate and epoxy resins, as a stabilizer or antioxidant
for many types of plastics such as polyvinyl chloride (PVC),
and as an inhibitor of end oxidation in PVC.1 Annual production
capacity of this compound in Japan is about 490 000 tons.2 Re-
cently, considerable attention has been focused on BPA as well
as other phenolic compounds as endocrine-disrupting chemicals.
In particular, numerous in vivo and in vitro studies have demon-
strated the estrogenic properties of this compound.3 We have re-
cently identified 5-hydroxy-1-(40-hydroxyphenyl)-1,3,3-trime-
thylindan, as one of impurities in samples of an industrial grade
of bisphenol A.4 This compound, like BPA itself, possesses a
phenolic hydroxy group para to other substituents, and thus re-
sembles 17ꢁ-estradiol (Chart 1), the main female hormone, and
might also have estrogenic properties. Synthesis was necessary
to provide sufficient material for estrogenic activity assays.
However, no appropriate synthetic intermediate was commer-
cially available, and no convenient synthetic method for the
compound has hitherto been reported. In this study, we establish-
ed a facile synthetic route to 5-hydroxy-1-(40-hydroxyphenyl)-
1,3,3-trimethylindan from commercially available ꢀ-methyl-
styrene and assessed the estrogenic activity of this compound us-
ing yeast two-hybrid assays incorporating the human estrogen
receptor or the medaka fish (Oryzias latipes) estrogen receptor.5
Synthesis of 5-hydroxy-1-(40-hydroxyphenyl)-1,3,3-tri-
1
and 6 in the ratio of 4 to 6, as analyzed by H NMR and GC–
MS.7 Nitric acid and acetic anhydride were removed under re-
duced pressure, and the dissolution and evaporation cycle was
performed 5 times, at first using water (50 mL each) and then
5 times using benzene (30 mL each) to remove water as an azeo-
tropic mixture, according to the method of Nomoto et al.8
The yellow residue containing dinitroindans 5 and 6 in 2-
propanol (50 mL) was heated to reflux. Once it dissolved, Pd/
a
b
2
3
4
NO2
NH2
c
d
R1
R3
R4
R2
OH
OH
5. R1 = H, R2 = NO2
6. R1 = NO2, R2 = H
7. R3 = H, R4 = NH2
8. R3 = NH2, R4 = H
HO
OH
HO
HO
1
2
9
Scheme 1. (a) TFA, rt 12 h; (b) HNO3/(Ac)2O, 0 ꢁC, 4 h; (c) Pd/C,
hydrazine, reflux, 4 h; (d) H2SO4, NaNO2, H2O, 0 ꢁC/heat.
Chart 1. Chemical structures for bisphenol A (1) and 17ꢁ-estradiol
(2).
Copyright ꢀ 2005 The Chemical Society of Japan

Chemistry Letters Vol.34, No.2 (2005)
189
Table 1. Estrogenic activity of 9 and BPA in yeast two-hybrid assays
for hERꢀ and mERꢀ
C (0.25 g) was added followed by 15-mL hydrazine monohy-
drate, which was slowly added dropwise. The mixture was re-
fluxed for 4 h, and then the catalyst was removed by filtration un-
der nitrogen. The reaction mixture was concentrated under re-
duced pressure and subjected to the dissolution and evaporation
cycle 5 times using benzene (50 mL each). This residue was
considered to contain diaminoindans 7 and 8 as analyzed by
GC–MS.9
hERꢀ assay
ECx10; nMa
mERꢀ assay
ECx10; nMa
Compd.
9
BPA
R. A.b
R. A.b
2400
2800
1.2
1.0
230
2000
8.7
1.0
a
Estrogenic activity was recorded as the ECx10 which was defined as
the concentration of test chemical solution producing a chemilumines-
cent signal 10x that of the blank control. b Activity relative to BPA.
In the final step of synthesis, the above residue was dis-
solved in 10% sulfuric acid (20 mL) to give a dark red solution.
To the mixture, cooled sodium nitrite (3 g) in H2O (10 mL) was
added dropwise at 0 ꢁC, and then the mixture was heated under
reflux for 20 min. The product from this reaction was concentrat-
ed under reduced pressure and the residue was applied to a silica-
gel column (300 ꢂ 30 mm). Solvent was removed by rotary
evaporation from each fraction separately and the residues were
examined by 1H NMR. The desired 9 was eluted by dichlorome-
thane–acetone (9:1) together with a by-product. This by-product
could not be separated from the main product on silica-gel TLC
using dichloromethane–acetone (9:1) as a developing solvent.
The mixture was finally separated by HPLC to afford pure 9.10
The total yield from ꢀ-methylstyrene was 376 mg (3.6%). The
structure of this product was confirmed by NMR spectra, as
shown in Figure 1.11
Estrogenic activity of 5-hydroxy-1-(40-hydroxyphenyl)-
1,3,3-trimethylindan (9) by yeast two-hybrid assays: Accord-
ing to the synthetic scheme described here, 9 can be easily ob-
tained in a practical yield without using any special reagents.
This synthetic work facilitated definitive estrogenicity assays
of 9, which is found as one of impurities in industrial grade
BPA. Estrogenicity of 9 and purified laboratory reagent BPA
are presented in Table 1. The assay using the mERꢀ showed that
the estrogenicity of 9 was 8.7 times that of BPA. In the assay us-
ing hERꢀ, 9 had 1.2 times the activity of BPA.
grade BPA. Confirmation of the in vivo activity of 9 would indi-
cate that the potential estrogenicity of industrial grade BPA
should be re-examined.
References and Notes
1
2
3
M. Ash and I. Ash, ‘‘Handbook of Plastic and Rubber Additives,’’ Gower,
Hampshire, UK (1995).
http://www.safe.nite.go.jp/, ‘‘Foundation of Safety Management Infrastruc-
ture for Chemical Substances’’
a) E. J. Routledge and J. P. Sumpter, Environ. Toxicol. Chem., 15, 241 (1996).
b) N. G. Coldham, M. Dave, S. Sivapathasundaram, D. P. McDonnell, C.
Connor, and M. J. Sauer, Environ. Health Perspect., 105, 734 (1997). c) R.
Steinmetz, N. G. Brown, D. L. Allen, R. M. Bigsby, and N. Ben-Jonathan,
Endocrinology, 138, 1780 (1997). d) C. A. Staples, P. B. Dorn, G. M. Klecka,
S. T. Block, and L. R. Harris, Chemosphere, 36, 2149 (1998).
M. Terasaki, M. Nomachi, J. S. Edmonds, and M. Morita, Chemosphere, 55,
927 (2004).
a) F. Shiraishi, H. Shiraishi, J. Nishikawa, T. Nishihara, and M. Morita,
J. Environ. Chem., 10, 57 (2000). b) T. Nishikawa et al., unpublished data.
The amplification of the gene for the medaka estrogen receptor and its intro-
duction to a yeast recombinant plasmid for use in the yeast two-hybrid assay
has shown that, in general, the relative estrogenic activities to xenoestrogens
of the medaka estrogen receptor (ER) are higher than to the human ER.
1H NMR (500 MHz, methanol-d4): ꢂ 0.98, 1.32, 1.65 (s, 3H, Me), 2.18 (d, 1H,
J ¼ 13:2 Hz), 2.42 (d, 1H, J ¼ 12:6 Hz), 7.06–7.26 (m, 9H, Ar–H); 13C NMR
(125 MHz, methanol-d4): ꢂ 151.89, 150.95, 148.47, 127.63, 126.99, 126.37,
126.31, 125.18, 124.62, 122.23, 59.12, 50.52, 42.43, 30.11, 29.72, 29.27;
HRFAB MS positive mode (M þ H): 237.1641 (calcd. for 237.1643;
C18H22).
4
5
6
7
1H NMR (500 MHz, methanol-d4): ꢂ 1.08, 1.41, 1.78 (6H, Me), 2.38 (2H),
2.57 (2H), 7.38 (d, 1H, J ¼ 8:0 Hz), 7.42 (d, 4H, J ¼ 9:0 Hz), 7.50 (d, 1H,
J ¼ 8:5 Hz), 8.01 (d, 1H, J ¼ 1:5 Hz), 8.12 (d, 1H, J ¼ 1:5 Hz), 8.15 (d,
4H, J ¼ 8:8 Hz), 8.17 (dd, 1H, J ¼ 2:5 and 9.0 Hz), 8.23 (dd, 1H, J ¼ 2:5
and 8.5 Hz); The mass chromatogram by GC–MS showed two peaks, which
gave the same mass fragment at m=z 326 (Mþ), 311 (M–CH3), 265 (M–CH3,
–NO2).
BPA is manufactured by the condensation of phenol with
acetone in the presence of an acid catalyst. Different manufactur-
ing processes are likely to yield different relative quantities of
the product and of impurities. Trace impurities present in low
concentrations, arising either during synthesis or storage, may
lead to markedly different activities than might be expected from
the activities of the individual components.12
8
9
S. Nomoto, M. Kozono, H. Mita, and A. Shimoyama, Bull. Chem. Soc. Jpn.,
74, 1975 (2001).
MS (EI) data for both 7 and 8: m=z 266 (Mþ), 251, 236, 221, 208, 193, 180,
165, 158, 143, 130, 118, 106, 93, 77, 65.
The work reported in the current paper has demonstrated the
endocrine-disrupting properties of 9, a contaminant in industrial
10 a) Column: Inertsil ODS-3 (250 ꢂ 20 mm; 5 mm; GL Sciences, Tokyo,
Japan); Elution: acetonitrile-H2O (5:5); Detector: UV 270 nm. b) The by-
product was identified as 6-hydroxy-1-(40-hydroxyphenyl)-1,3,3-trimethyl-
indan as judged from MS, NMR spectra and Nuclear Overhauser Effect
(NOE) difference experiments (methanol-d4). Selected physical data for this
compound: mp 182–184 ꢁC; 1H NMR (500 MHz, methanol-d4): ꢂ 0.98, 1.27,
1.58 (s, 3H, Me), 2.11 (d, 1H, J ¼ 13:8 Hz), 2.33 (d, 1H, J ¼ 13:8 Hz), 6.47
(d, 1H, J ¼ 2:3 Hz), 6.63 (d, 2H, J ¼ 9:2 Hz), 6.68 (dd, 1H, J ¼ 1:7 and
8.0 Hz), 6.97 (d, 2H, J ¼ 9:2 Hz), 6.98 (d, 1H, J ¼ 8:0 Hz). NOE experiment:
enhancements at ꢂ 6.47, 6.97, and 2.11 (irradiation at Me, ꢂ 1.58), at 6.98,
2.11, and 0.98 (at Me, ꢂ 1.27), at 6.98, 2.33 and 1.27 (at Me, ꢂ 0.97); HR
FAB MS positive mode [M þ H]þ: 269.1539 (calcd for 269.1542;
C18H21O2).
11 Selected physical data for 9: mp 181–183 ꢁC; 1H NMR (500 MHz, methanol-
d4): ꢂ 0.96, 1.27, 1.57 (s, 3H, Me), 2.11 (d, 1H, J ¼ 13:2 Hz), 2.33 (d, 1H,
J ¼ 12:6 Hz), 6.57 (d, 1H, J ¼ 2:3 Hz), 6.62 (d, 2H, J ¼ 9:2 Hz), 6.66 (dd,
1H, J ¼ 2:3 and 8.6 Hz), 6.87 (d, 1H, J ¼ 8:1 Hz), 6.95 (d, 2H,
J ¼ 9:2 Hz). NOE experiment: enhancements at ꢂ 6.87, 6.95, and 2.11
(irradiation at Me, ꢂ 1.57), at 6.57, 2.11, and 0.96 (at Me, ꢂ 1.27), at 6.57,
2.33, and 1.27 (at Me, ꢂ 0.96); HR FAB MS positive mode [M þ H]þ:
269.1540 (calcd for 269.1542; C18H21O2).
7.0
6.5
2.5
δ / PPM
2.0
1.5
1.0
Figure 1. 1H NMR spectra of 5-hydroxy-1-(40-hydroxyphenyl)-
1,3,3-trimethylindan (9).
12 P. Dureja, R. S. Tanwar, and P. P. Choudhary, Chemosphere, 41, 1407
(2000).
Published on the web (Advance View) January 15, 2005; DOI 10.1246/cl.2005.188