Ligands with dual vitamin D3-agonistic and androgen-antagonistic activities

Article abstract of DOI:10.1016/j.bmcl.2005.06.044

Ligands possessing dual vitamin D₃-agonistic (estimated as HL-60 monocytic cell differentiation induction) and androgen-antagonistic (estimated as testosterone-induced SC-3 cell growth inhibition) activities with various activity spectra were p

Full text of DOI:10.1016/j.bmcl.2005.06.044

Bioorganic & Medicinal Chemistry Letters 15 (2005) 4327–4331
Ligands with dual vitamin D3-agonistic and
androgen-antagonistic activities
Shinnosuke Hosoda,a Aya Tanatani,a,* Ken-ichi Wakabayashi,a Yusuke Nakano,a
Hiroyuki Miyachi,a Kazuo Nagasawab and Yuichi Hashimotoa,*
aInstitute of Molecular & Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
bDepartment of Biotechnology and Life Science, Faculty of Technology, Tokyo University of Agriculture and Technology,
2-24-16 Naka-machi, Koganei-shi, Tokyo 184-8588, Japan
Received 19 May 2005; revised 9 June 2005; accepted 14 June 2005
Available online 12 July 2005
Abstract—Ligands possessing dual vitamin D3-agonistic (estimated as HL-60 monocytic cell differentiation induction) and
androgen-antagonistic (estimated as testosterone-induced SC-3 cell growth inhibition) activities with various activity spectra were
prepared based on a substituted bis-phenylmethane skeleton. Some of them were revealed to be potent androgen antagonists with
a nonsecosteroidal vitamin D3 skeleton.
Ó 2005 Elsevier Ltd. All rights reserved.
1. Introduction
that 1,25-D3 might be an antagonistic ligand for
nuclear androgen receptor (AR). In fact, we found that
1,25-D3 binds to AR in a competitive manner with its
cognate ligand, testosterone (details will be published
elsewhere). The calculated Ki value of 1,25-D3 for bind-
ing to AR was 2.2 lM, which is 244 times larger than
that for binding to VDR. In spite of this, that is the
affinity ratio of 1,25-D3 toward AR and VDR being
1:244, the specific binding of 1,25-D3 to AR might
have some biological meaning, especially in the case
of 1,25-D3-induced cell growth inhibition of andro-
gen-dependent prostate tumor cell lines. Moreover, this
result suggests that 1,25-D3 can act as a dual ligand for
both VDR and AR, though its activity toward the
latter is antagonistic.
A relationship between vitamin D3 and prostate cancer
has been well documented.1–4 For example, epidemio-
logical evidence suggests that low exposure to sunlight
and vitamin D deficiency may be risk factors for pros-
tate cancer mortality.1,2 In addition, 1a,25-dihydroxy-
vitamin D3 (1,25-D3), which is an active metabolite of
vitamin D3 and a ligand of nuclear vitamin D3 receptor
(VDR), has been reported to induce apoptosis or differ-
entiation in many cell types, including prostate tumor
cell lines.3–6 Well-established activities elicited by 1,25-
D3 are induction of monocytic cell differentiation of
human leukemia cell line HL-60 and growth inhibition
of androgen-dependent human prostate tumor cell
lines.3,7–10 Although the 1,25-D3-induced cell differentia-
tion of HL-60 is mediated by direct binding and activa-
tion of VDR by 1,25-D3, the molecular mechanism and
the role of VDR in 1,25-D3-induced growth inhibition of
androgen-dependent cell lines remain obscure.3,9,10
A group at Ligand Pharmaceuticals has developed the
so-called nonsecosteroidal vitamin D3 agonists, includ-
ing LG190155 (1) and LG190178 (7) (Table 1), with a
bis-phenol skeleton.16,17 These compounds have been
reported to act as vitamin D3 agonists by binding and
activating VDR.16,17 We suspected that these com-
pounds might also act as androgen antagonists, as
1,25-D3 does. Therefore, we prepared several nitrogen-
containing derivatives of LG190155 (1)/LG190178 (7),
and examined their biological activities. One of autho-
rized and specific biological activity of vitamin D3
is HL-60 monocytic cell differentiation-inducing
activity.16,17 This activity was defined as vitamin D3 ago-
nistic activity in this paper. Similarly, inhibition of
During our structural development studies of nuclear
receptor antagonists, including vitamin D3 antagonists
and androgen antagonists,11–15 we noticed that 1,25-
D3 potently inhibits androgen-induced cell growth of
Shionogi Carcinoma SC-3 cells. This led us to suspect
Keywords: Vitamin D3; Androgen antagonist; Bisphenylmethane.
*
Corresponding authors. E-mail: bmcyfh@iam.u-tokyo.ac.jp
0960-894X/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2005.06.044

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S. Hosoda et al. / Bioorg. Med. Chem. Lett. 15 (2005) 4327–4331
Table 1. Structures and results of biological assays of bis-phenylmethane derivatives 1–11
Vitamin D3 agonistic
activity (ED50, nM)a
Androgen antagonistic
activity (IC50, nM)b
Activity ratioc
AR-binding affinity
(Ki, nM)
b
(ED50a/IC50
)
1: X = O, Y = O (LG190155)
2: X = O, Y = NH
3: X = NH, Y = NH
410
450
450
1900
1200
1000
0.22
0.38
0.45
ND
ND
ND
4
1200
1000
1.20
ND
5
6
900
370
6800
820
0.13
0.45
3380
2900
7: X = O (LG190178)
8: X = NH
44
52
19
9.0
2.31
5.78
ND
1508
9
110
7.6
14.5
1170
10
11
1500
ND
3500
ND
0.43
—
ND
ND
ND: not detected.
a Vitamin D3 agonistic activity was estimated as ED50 values of HL-60 monocytic cell differentiation induction measured by NBT-positivity.
b Androgen antagonistic activity was estimated as IC50 values on testosterone-induced cell growth of SC-3 cells.
c Activity ratio was defined as vitamin D3 activity (ED50 value)/androgen antagonistic activity (IC50 value).
androgen-induced cell growth of SC-3 cells was defined
as androgen-antagonistic activity.12,13,15
various positions (like the 25-hydroxyl group of the side
chain of 1,25-D3), that is, compound 5 and its hybrid
compound with 1/2 (6), (iii) the oxidized analog of 8, that
is, compound 9, and (iv) compounds which possess a free
phenolic hydroxyl group derived from 2 and 8, that is,
compounds 10 and 11, respectively. These compounds
were obtained by usual organic synthetic methods, and
the structures were confirmed by the spectroscopic
data.18–26 A typical synthetic scheme (for the synthesis
of compounds 3–5) is shown in Scheme 1.
2. Chemistry
First we designed nitrogen analogs of LG190155 (1)/
LG190178 (7), that is, 2, 3, and 8, in order to allow intro-
duction of a substituent at the nitrogen atom, aiming at
eventual conversion of the compounds to antagonists,
based on our earlier development studies on nitrogen-
containing vitamin D3 antagonists, DLAMs.11,14 Next,
we designed (i) the reduced analog of 3, that is, com-
pound 4, (ii) compounds possessing hydroxyl groups at
It is noteworthy that direct substitution reaction of the
bisphenol derivative 12 with an aniline derivative 14
proceeded efficiently to yield compound 15 (Scheme 2).

S. Hosoda et al. / Bioorg. Med. Chem. Lett. 15 (2005) 4327–4331
4329
Scheme 1. Reagents and conditions: (a) Tf2O, Et3N, CH2Cl2, 2 h, 97%; (b) BnNH2, Pd(OAc)2, 2-(di-tert-butylphosphino)biphenyl, Cs2CO3, toluene,
100 °C, 14 h, 54%; (c) H2, Pd(OH)2/C, DMF, 16 h, 95%; (d) 1-chloropinacolone, KI, Et3N, DMF, 24 h, 59%; (e) NaBH4, sec-BuOH, 30 min, 98%;
(f) 4-bromo-2-methyl-2-butanol, Et3N, DMF, 60 °C, 22 h, 31%.
Scheme 2. Reagents and conditions: (g) neat, 180 °C, 2.5–15 h, 72%; (h) 1-chloropinacolone, NaH, DMF, 1 h, 97%; (i) glycidol, EtOH, 19 h, 57%.
This reaction seems to be general, because the substitu-
tion reaction of 12 with various aniline derivatives of 14
gave the corresponding adducts in good yields (generally
50–80%; details will be published elsewhere). A similar
reaction, that is, transalkylation of 4,40-(1-methylethyl-
idene)bisphenol with 2,6-diphenylphenol, was reported
by Wang and Hay, though the reaction proceeds in
the presence of methanesulfonic acid.27
of the prepared compounds (1–11) showed androgen-ag-
onistic activity (growth promotion of SC-3 cells). The
binding affinity of the compounds toward AR was also
evaluated as described previously.12,13,15 Briefly, recom-
binant AR was prepared from cytosol of Escherichia coli
transformed with a human AR LBD expression vector
(GST-hARLBD), which encodes amino acids 627–919
of human AR fused with GST protein under the lac pro-
moter.29 The binding activity of the GST-hARLBD thus
prepared for [3H]testosterone, that is, the Kd (dissocia-
tion constant) value, was determined to be 1.4 nM by
Scatchard analysis, and this value is close to that of
AR prepared from intact SC-3 cells. Although, the ami-
no acid sequences of mouse AR and human AR are
slightly different from each other, they possess basically
the same ligand selectivity as far as examined.12,15 The
binding activity of a test compound was determined by
incubation of GST-hARLBD with [3H]testosterone in
the presence of various concentrations of the test com-
pound. The concentration of a test compound that
inhibits [3H]testosterone binding by 50% (IC50 value)
was determined, and the Ki value was calculated based
on the Kd value of [3H]testosterone (Table 1).
3. Cell biological assays
Vitamin D3-agonistic activity of the compounds was
evaluated by measurement of HL-60 cell differentiation
as described previously.14,28 Briefly, HL-60 cells were
incubated in RPMI 1640 medium in the presence or
absence of a test compound for three days. Treated
HL-60 cells were mixed with phosphate-buffered saline
(PBS) containing 0.2% nitroblue tetrazolium (NBT)
and 20 nM 12-O-tetradecanoylphorbol 13-acetate
(TPA) in a 1:1 (v/v) ratio and incubated at 37 °C for
20 min. NBT positivity was measured by counting
200–300 cells. The cell differentiation was also con-
firmed morphologically by microscopy after Wright–Gi-
emsa staining. Of course, the percentage values differed
from experiment to experiment, but the results were
basically reproducible. A typical set of ED50 values is
presented in Table 1.
4. Results and discussion
As shown in Table 1, LG190155 (1) showed moderate
HL-60 cell differentiation-inducing activity (vitamin
D3-agonistic activity) with an EC50 value of 410 nM,
which is consistent with the reported activity.16,17 We
found that this compound also possesses SC-3 cell
growth-inhibitory activity (androgen-antagonistic activ-
ity), as we suspected, though the activity was weak (IC50
value of 1900 nM). Though LG190155 (1) possesses
both vitamin D3-agonistic and androgen-antagonistic
activities, the activity ratio (ratio of ED50 value for
vitamin D3-agonistic activity and IC50 value for andro-
gen-antagonistic activity) was 0.22, meaning that this
compound can be regarded primarily as a vitamin D3
agonist, rather than an androgen antagonist.
Androgen-antagonistic activity of the compounds was
evaluated by measurement of inhibition of androgen-in-
duced SC-3 cell growth, as described previously.12,13,15
Briefly, SC-3 cells were cultured in MEM medium sup-
plemented with 10% FBS and 10 nM testosterone in
the presence or absence of a test compound for three
days at 37 °C under 5% CO2. The number of cells with
testosterone alone was defined as 100%. The concentra-
tion of test compounds that inhibited by 50% the
increase of the cell number induced by 10 nM testoster-
one was quantified (IC50) (Table 1). Androgen-agonistic
activity can be evaluated in the same cell line, but none

4330
S. Hosoda et al. / Bioorg. Med. Chem. Lett. 15 (2005) 4327–4331
Exchange of the one or two phenolic oxygen atom(s) of
LG190155 (1) with a nitrogen atom(s), resulting in com-
pounds 2 and 3, respectively, slightly lowered the
vitamin D3 activity and increased the androgen-antago-
nistic activity. The androgen-antagonistic activity of
these three compounds increased in the order of the
number of oxygen–nitrogen exchange(s), that is,
1 < 2 < 3. The activity ratio values of 2 and 3 were
0.38 and 0.45, respectively.
seems to lower vitamin D3-agonistic activity and to
enhance androgen-antagonistic activity (comparisons
among 1–3, and between 7 and 8), (2) a 1,2-diol group
seems to be important for potent vitamin D3-agonistic
activity (comparison of 1–6 vs compounds 7–9), and
(3) exchange of the phenolic oxygen atom-containing
side chain of 6 with a nitrogen atom-containing side
chain with reduction and translocation of a hydroxyl
group, giving 5 seems to weaken both vitamin D3-ago-
nistic activity and androgen-antagonistic activity, but
the effect is much greater for the latter activity. These
results prompted us to evaluate a hybrid compound 9
(Scheme 2).
Reduction of 3, giving 4, resulted in a lower vitamin D3
activity but the androgen-antagonistic activity was not
affected, and its activity ratio value was further raised
to 1.20. Consequently, compound 4 can be regarded as
a dual ligand possessing both vitamin D3 activity and
androgen-antagonistic activity, although AR binding
affinity could not be observed under the experimental
conditions used.
Compound 9 was revealed to possess very potent
androgen-antagonistic activity with an IC50 value of
7.6 nM, which is 24 times more potent than hydroxy-
flutamide (IC50 = 180 nM). Although 9 possess moder-
ate vitamin D3-agonistic activity with an EC50 value of
110 nM, the activity ratio is 14.5, and it also possesses
rather potent AR-binding affinity (Ki value of
1170 nM). Therefore, 9 can be regarded as a potent
androgen antagonist with additional vitamin D3-ago-
nistic activity. The tertiary butylcarbonylmethyl group
of 9 seems to be important for both vitamin D3-agonis-
tic and androgen-antagonistic activities because its
removal, giving 11, resulted in disappearance of the
activities. Interestingly, compound 10, a de-butyl-
carbonylmethylated analog of 2 with a free phenolic
hydroxyl group, possesses both vitamin D3 and andro-
gen-antagonistic activities, though they are very weak
compared with those of 2.
Translocation of two hydroxyl groups of 4, giving 5,
resulted in a slight increase of vitamin D3 activity, but
the androgen-antagonistic activity was greatly lowered.
Consequently, at least in terms of the cell biological as-
says performed here, compound 5 can be recognized as
almost a pure vitamin D3 agonist (the activity ratio is
0.13). A hybrid compound of 5 with 1/2, that is, 6,
showed a further increase of vitamin D3-agonistic activ-
ity and great potentiation of androgen-antagonistic
activity. It should be noted that both 5 and 6 possess
moderate binding affinity toward AR. Although we
cannot interpret this lack of a precise correlation
between AR affinity and androgen-antagonistic activity
evaluated in terms of SC-3 cell growth inhibitory activ-
ity at this stage, AR affinity is not necessarily correlated
with androgen-antagonistic activity, especially for AR
antagonists, and lack of such a relationship is often
observed.12,13 One possible interpretation is different
efficacy among AR/androgen antagonist complexes in
recruiting corepressor(s).
In conclusion, several compounds with a bis-phenyl-
methane skeleton (2–6 and 8–11) were derived from
nonsecosteroidal vitamin D3 [LG190155 (1) and
LG190178 (7)]. The prepared compounds showed vari-
ous activity ratio values ranging from 0.13 to 14.5.
For convenience, these compounds can be classified into
three categories, that is, vitamin D3 agonists (com-
pounds with activity ratio values of less than 0.4),
androgen antagonists (compounds with activity ratio
values of more than 2.5), and dual ligands (compounds
with activity ratio values of 0.4–2.5). Then, compounds
1, 2, and 5 are vitamin D3 agonists, compounds 3, 4, 6,
and 7 are dual ligands, and compounds 8 and 9 are
androgen antagonists (with activity ratios of 5.78 and
14.5, respectively). In particular, compound 9 is a very
potent and selective androgen antagonist with a nonse-
costeroidal vitamin D3 skeleton. Further structural
development studies and investigation of structure–
activity relationships are in progress.
LG190178 (7) showed very potent vitamin D3 activity,
as reported.16,17 We found that LG190178 (7) possess
a potent androgen-antagonistic activity with an IC50
value of 19 nM, as we had suspected. Its activity ratio
was 2.31, so, it can be recognized as a dual ligand
possessing both vitamin D3 activity and androgen-
antagonistic activity. For the aza analog of
LG190178 (7), that is, compound 8, the vitamin D3
activity was slightly lowered, but the androgen-antag-
onistic activity was potentiated, as was found in the
case of nitrogen–oxygen exchange(s) in compounds
1–3. Compound 8 possess potent binding affinity
toward AR with a Ki value of 1508 nM, which is
comparable with that of the well-known androgen
antagonist, hydroxyflutamide (Ki = 936 nM), and its
activity ratio was 5.78, meaning that compound 8
can be regarded as an androgen antagonist rather
than vitamin D3 agonist.
Acknowledgments
The work described in this paper was partially support-
ed by Grants-in-Aid for Scientific Research from the
Ministry of Education, Culture, Sports, Science and
Technology, Japan, and the Japan Society for the Pro-
motion of Science, the Mochida Memorial Foundation,
and the Uehara Memorial Foundation for Medical and
Pharmaceutical Research.
Although detailed structure–activity relationship studies
remain to be performed, some features could be extract-
ed from the results presented here, that is, (1) exchange
of a phenolic oxygen atom(s) with a nitrogen atom(s)

S. Hosoda et al. / Bioorg. Med. Chem. Lett. 15 (2005) 4327–4331
4331
J = 12.4, 10.3 Hz, 2H), 2.10 (s, 6H), 2.00 (q, J = 7.3 Hz,
4H), 0.99 (s, 9H), 0.60 (t, J = 7.3 Hz, 6H).
References and notes
21. 3,3-Bis[4-(3-Hydroxy-3-methylbutylamino)-3-methylphe-
nyl]pentane (5): HRMS: 454.3562 (calcd 454.3559). 1H
NMR (500 MHz, CDCl3/d): 6.95–6.90 (m, 3H), 6.81 (d, J
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2.24 (s, 3H), 2.07 (s, 3H), 2.00 (q, J = 7.3 Hz, 4H), 1.85 (t,
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22. 1-(4-{3-[4-(3-Hydroxy-3-methylbutylamino)-3-methylphe-
nyl]pentan-3-yl}-2-methylphenoxy)-3,3-dimethylbutan-2-
one (6): HRMS: 467.3388 (calcd 467.3399). 1H NMR
(500 MHz, CDCl3/d): 6.95–6.90 (m, 3H), 6.81 (d,
J = 1.7 Hz, 1H), 6.57 (d, J = 8.6 Hz, 1H), 6.49 (d,
J = 8.6 Hz, 1H), 4.82 (s, 2H), 3.30 (t, J = 6.6 Hz, 2H),
2.24 (s, 3H), 2.07 (s, 3H), 2.00 (q, J = 7.3 Hz, 4H), 1.85 (t,
J = 6.6 Hz, 2H), 1.31 (s, 6H), 1.25 (s, 9H), 0.59 (t,
J = 7.3 Hz, 6H).
23. 3-(4-{3-[4-(2-Hydroxy-3,3-dimethylbutoxy)-3-methylphe-
nyl]pentan-3-yl}-2-methylphenylamino)- propane-1,2-diol
(8): HRMS: 457.3190 (calcd 457.3192). 1H NMR
(500 MHz, CDCl3/d): 6.97–6.92 (m, 3H), 6.83 (d, J =
1.7 Hz, 1H), 6.69 (d, J = 8.2 Hz, 1H), 6.55 (d, J = 6.9 Hz,
1H), 4.10–4.07 (m, 1H), 4.01 (m, 1H), 3.87–3.81 (m, 2H),
3.71–3.67 (m, 2H), 3.33 (dd, J = 12.8, 4.3 Hz, 1H), 3.25–
3.21 (m, 1H), 2.17 (s, 3H), 2.11 (s, 3H), 2.01 (q, J = 7.3 Hz,
4H), 1.01 (s, 9H), 0.60 (t, J = 7.3 Hz, 6H).
24. 1-(4-{3-[4-(2,3-Dihydroxypropylamino)-3-methylphenyl]-
pentan-3-yl}-2-methylphenoxy)-3,3-dimethylbutan-2-one
(9): HRMS: 455.3040 (calcd 455.3036). 1H NMR
(500 MHz, CDCl3/d): 6.94–6.89 (m, 3H), 6.82 (d,
J = 2.1 Hz, 1H), 6.55 (d, J = 8.5 Hz, 1H), 6.49 (d,
J = 8.1 Hz, 1H), 4.83 (s, 2H), 4.01 (m, 1H), 3.82(dd,
J = 11.1, 3.4 Hz, 1H), 3.70–3.66 (m, 1H), 3.33 (dd,
J = 12.8, 4.3 Hz, 1H), 3.25–3.21 (m, 1H), 2.23 (s, 3H),
2.11 (s, 3H), 2.00 (q, J = 7.3 Hz, 4H), 1.25 (s, 9H), 0.59 (t,
J = 7.3 Hz, 6H).
25. 1-{4-[3-(4-Hydroxy-3-methylphenyl)pentan-3-yl]-2-meth-
ylphenylamino}-3,3-dimethylbutan-2-one (10): HRMS:
381.2658 (calcd 381.2668). 1H NMR (500 MHz, CDCl3/
d): 6.94–6.87 (m, 3H), 6.84 (d, J = 2.1 Hz, 1H), 6.64 (d,
J = 8.6 Hz, 1H), 6.40 (d, J = 8.1 Hz, 1H), 4.53 (br s, 1H),
4.13 (s, 2H), 2.19 (s, 3H), 2.16 (s, 3H), 2.00 (q, J = 7.3 Hz,
4H), 1.24 (s, 9H), 0.59 (t, J = 7.3 Hz, 6H).
16. Boehm, M. F.; Fitzgerald, P.; Zou, A.; Elgort, M. G.;
Bischoff, E. D.; Mere, L.; Mais, D. E.; Bissonnette, R. P.;
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18. 1-(4-{3-[4-(3,3-Dimethyl-2-oxobutylhydroxy)-3-methyl-
phenyl]pentan-3-yl}-2-methylphenylamino)-3,3-dimeth-
ylbutan-2-one (2): mp 106 °C. HRMS: 479.3392 (calcd
1
479.3399). H NMR (500 MHz, CDCl3/d): 6.93–6.89 (m,
3H), 6.83 (br s, 1H), 6.49 (d, J = 8.1 Hz, 1H), 6.39 (d,
J = 8.1 Hz, 1H), 4.82 (s, 2H), 4.50 (br s, 1H), 4.13 (d,
J = 4.3 Hz, 2H), 2.23 (s, 3H), 2.16 (s, 3H), 1.99 (q,
J = 7.3 Hz, 4H), 1.25 (s, 9H), 1.24 (s, 9H), 0.59 (t,
J = 7.3 Hz, 6H). Anal. Calcd N, 2.80; C, 77.39; H, 9.37.
Found: N, 2.92; C, 77.62; H, 9.46.
26. 4-{3-[4-(2,3-Dihydroxypropylamino)-3-methylphenyl]pen-
tan-3-yl}-2-methylphenol (11): HRMS: 357.2344 (calcd
1
357.2304). H NMR (500 MHz, CDCl3/d): 6.95–6.83 (m,
19. 3,3-Bis[4-(3,3-Dimethyl-2-oxobutylamino)-3-methylphe-
nyl]pentane (3): HRMS: 478.3562 (calcd 478.3559). 1H
NMR (500 MHz, CDCl3/d): 6.95 (dd, J = 8.5, 2.1 Hz, 2H),
6.85 (d, J = 2.1 Hz, 2H), 6.39 (d, J = 8.5 Hz, 2H), 4.50 (br
s, 2H), 4.13 (s, 4H), 2.16 (s, 6H), 1.99 (q, J = 7.3 Hz, 4H),
1.24 (s, 18H), 0.59 (t, J = 7.3 Hz, 6H).
4H), 6.64 (d, J = 8.6 Hz, 1H), 6.55 (d, J = 8.1 Hz, 1H),
4.01 (m, 1H), 3.82 (dd, J = 11.1, 3.4 Hz, 1H), 3.70–3.66
(m, 1H), 3.32 (dd, J = 12.8, 4.3 Hz, 1H), 3.25–3.21 (m,
1H), 2.22 (s, 3H), 2.10 (s, 3H), 2.00 (q, J = 7.3 Hz, 4H),
0.60 (t, J = 7.3 Hz, 6H).
27. Wang, Z. Y.; Hay, A. S. Synthesis 1989, 471.
28. Kagechika, H.; Kawachi, E.; Hashimoto, Y.; Himi, T.;
Shudo, K. J. Med. Chem. 1988, 31, 2839.
29. Takahashi, H.; Ishioka, T.; Koiso, Y.; Sodeoka, M.;
Hashimoto, Y. Biol. Pharm. Bull. 2000, 23, 1387.
20. 3,3-Bis[4-(2-hydroxy-3,3-dimethylbutylamino)-3-methyl-
phenyl]-pentane (4): HRMS: 482.3878 (calcd 482.3872).
1H NMR (500 MHz, CDCl3/d): 6.95 (dd, J = 8.6, 2.1 Hz,
2H), 6.85 (br s, 2H), 6.53 (d, J = 8.6 Hz, 2H), 3.52 (d,
J = 10.3 Hz, 2H), 3.37 (dd, J = 12.4, 2.6 Hz, 2H), 2.99 (dd,