Synthesis of Selectively Protected Genistein Derivatives

Article abstract of DOI:10.1081/SCC-120026353

Differential functionalization of the phenolic groups in Genistein by sequential, silylation/acylation reactions, involving some unexpected regioselective O-silyl group replacement, is described.

Full text of DOI:10.1081/SCC-120026353

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Synthesis of Selectively Protected Genistein
Derivatives
Wiesław Szeja a , Gabriela Pastuch a , Ilona Wandzik a , Nikodem Kuźnik a & Grzegorz
Grynkiewicz b
a Faculty of Chemistry , Silesian University of Technology , Gliwice, Poland
b Pharmaceutical Research Institute , Warszawa, Poland
Published online: 16 Aug 2006.
To cite this article: Wiesław Szeja , Gabriela Pastuch , Ilona Wandzik , Nikodem Kuźnik & Grzegorz Grynkiewicz (2003)
Synthesis of Selectively Protected Genistein Derivatives, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 33:23, 4111-4121, DOI: 10.1081/SCC-120026353
To link to this article: http://dx.doi.org/10.1081/SCC-120026353
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SYNTHETIC COMMUNICATIONSÕ
Vol. 33, No. 23, pp. 4111–4121, 2003
Synthesis of Selectively Protected
Genistein Derivatives
Wieslaw Szeja,1 Gabriela Pastuch,1 Ilona Wandzik,1,
*
Nikodem Kuz
´
nik,1 and Grzegorz Grynkiewicz2
1Faculty of Chemistry,
Silesian University of Technology, Gliwice, Poland
2Pharmaceutical Research Institute, Warszawa, Poland
ABSTRACT
Differential functionalization of the phenolic groups in Genistein by
sequential silylation/acylation reactions, involving some unexpected
regioselective O-silyl group replacement, is described.
Key Words: Genistein; Silylation; Acylation.
*Correspondence: Ilona Wandzik, Faculty of Chemistry, Silesian University
of Technology, Krzywoustego 8, 44-100 Gliwice, Poland; E-mail: ilwan@
polsl.gliwice.pl.
4111
DOI: 10.1081/SCC-120026353
Copyright & 2003 by Marcel Dekker, Inc.
0039-7911 (Print); 1532-2432 (Online)
www.dekker.com

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4112
Szeja et al.
INTRODUCTION
Genistein 1 is a secondary metabolite of plant origin, belonging
to the isoflavone family, which evokes great interest because of its
pleiotropic biological activity and possible applications in therapy and
chemoprevention.[1–4] While studies of the biological activity of 1 are
plentiful (several 100 s of articles annually), its chemistry has attracted
relatively little attention, possibly because of scarce availability of the
substance. Although natural sources of 1 are rich and renewable
(cultivation of soy; Glycine max Merril), inherent problems connected
with the separation of complex mixtures of related natural products
seem to favor chemical synthesis as a base for future product development.
Nevertheless, general methods for isoflavone synthesis are not auto-
matically applicable to polyphenolic products and genistein (a triphenol)
is an example of the synthetic target for which temporary blocking of
phenolic function is advisable for efficient construction of chromenone
ring system.[5]
RESULTS AND DISCUSSION
Since the need for regioselective protection of phenolic group in
multifunctional natural compounds is a recurrent theme in their synthesis
as well as in subsequent derivatization, we were tempted to apply simple
synthetic means, consisting of sequential silylation/acylation reactions for
differentiation of phenolic functions in 1. As a result of this approach a
small collection of previously unreported derivatives of 1 (Figure 1),
listed in the following Table 1, has been generated. In the course of the
study we have observed unexpected differences in reactivity of regio-
isomeric tert-butyldimethylsilyl protecting groups, which shed new light
on their possible application in chemistry of polyphenolic substrates.
8
R1O
O
2
7
6
2'
5'
1'
3'
4'
3
4
5
OR2
O
6'
OR3
Figure 1. Genistein (R1 ¼ R2 ¼ R3 ¼ H) 1 and its derivatives.

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Genistein Derivatives
4113
Table 1. Summary of selectively functionalized derivatives of genistein (1).
Compound no.
R1
R2
R3
1
2
H
t-BDMS
H
H
H
H
Genistein
7-O-t-BDMS-1
H
3
H
t-BDMS
t-BDMS
t-BDMS
H
40-O-t-BDMS-1
4
t-BDMS
Ac
Ac
H
40,7-Di-O-t-BDMS-1
5,7-Di-OAc-40-O-t-BDMS-1
5,7-Di-OAc-1
7-OAc-40-O-t-BDMS-1
5-OAc-40,7-di-O-t-BDMS-1
7-O-t-BDMS-40-O-Ac-1
5-OBz-40,7-di-O-t-BDMS-1
7-OBz-40-O-t-BDMS-1
5,7-Di-OBz-40-O-t-BDMS-1
5-OAc-7-OBz-40-O-t-BDMS-1
5
Ac
Ac
H
6
7
Ac
t-BDMS
t-BDMS
Ac
8
t-BDMS
t-BDMS
t-BDMS
Bz
Ac
H
9
10
11
12
13
Bz
H
t-BDMS
t-BDMS
t-BDMS
t-BDMS
Bz
Bz
Bz
Ac
Ac—acetyl, t-BDMS—tert-butyldimetylsilyl, Bz—benzoyl.
Previous attempts at selective functionalization of 1 by action of
electrophilic reagents exploited differences in acidity of 7-OH and
40-OH and reversed nucleophilicity of the corresponding anions.[6,7]
Although acidity constants for particular phenol groups in 1 seem to
be a way apart in solution, (at least two orders of magnitude as calculated
for 7-OH and 40-OH) lack of solubility of genistein and some of its salts
can complicate an issue of selective reactivity for example in the case of
phase transfer reactions. In fact, it has been demonstrated with the help
of X-ray crystallography and molecular modeling, that basic nitrogen
interactions with less acidic phenolic groups also contribute significantly
to the structure of molecular complexes between genistein and amines.[8,9]
In keeping with the above, our provisional notion that all three
phenolic groups in 1 are sufficiently different in terms of ionization
constants to be easily distinguishable by action of any electrophilic
reagent was not supported by experiments. In fact upon direct action
of acylating, alkylating, and glycosylating reagents on 1 in the presence
of various basic reagents, low regioselectivity was observed, resulting in
formation of at least two mono substituted derivatives, accompanied by a
doubly functionalized product. Since such reaction mixtures proved
rather difficult to separate, an idea of temporary protecting group secur-
ing complete regioselective placement of the desired substituent was put
forward. tert-Butyldimethylsilyl group was chosen for our study on the
ground of the well-known facility of its introduction and removal as well

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4114
Szeja et al.
as its compatibility with various derivatizing procedures.[10,11] Treatment
of 1 with one molar equivalent of tert-butyldimethylsilyl chloride under a
variety of conditions, including phase-transfer catalysis, resulted invari-
ably in mixtures of 40-O- and 7-O-substituted silyl derivatives of 1 (respec-
tively 2 and 3). Under more rigorous conditions degradation of the
substrate was also observed, due to the isoflavone heterocyclic ring
cleavage in the presence of strong bases. On the other hand, reaction
of 1 with two molar equivalents of tert-butyldimethylsilyl chloride in
the presence of imidazole in DMF as a solvent resulted in formation in
good yield of a single derivative, which was identified as 7,40-di-O-t-
BDMS genistein 4. This derivative is perceived as a suitable precursor
for 5-O-acylated genistein derivatives, which are not available, by direct
functionalization procedures.
Acetylation of 4 under standard conditions with acetic anhydride—
pyridine gave unexpectedly selectively desilylated diacetyl derivative 5
and monoacetyl compound 7, as summarized in Table 2. Using an
excess of acetyl anhydride (4 equiv.) and prolonging the reaction time
resulted in isolation of compound 5 as the only product in high yield
(Entry 3). A similar result was observed in reaction of 4 with less reactive
benzoic anhydride (Entry 5). The only product isolated was 7-mono-
benzoate 11 which after subsequent acetylation yielded protected
compound 13 (Entry 7), providing an example of fully differentiated
functionalization of all phenolic groups. Desilylation of 5 (Bu4NF,
THF) resulted in formation of genistein derivative 6, with 40-OH
hydroxyl group unprotected (Sch. 1).
An attempt to acylate compound 4 by phthalic anhydride
under analogous conditions was unsuccessful, leading to the product of
regioselective deprotection of 7-OH, instead of expected hemiester. This
procedure, an alternative for treatment with mildly acidic medium, offers
an advantage for preparation of 40-O-silylated genistein derivative 3 over
direct equimolar silylation of 1. Compound 3 was identified by NMR
analysis of the monosilylation reaction mixture as the minor constituent,
which could not be isolated in pure state. This compound is considered
an important intermediate, allowing for selective 7-OH derivatization of
1, due to much lower reactivity of the intramolecular bonded therefore
noncompeting, 5-OH group.
1
All described compounds were identified with the aid of H NMR
spectroscopy. The site of silyl substitution can be easily deduced from
chemical shifts of singlet representing six protons of two methyl groups in
silyl function. Mentioned protons in mono-7-O-t-BDMS genistein (2)
resonate at lower field than those at mono 40-O-t-BDMS genistein (3).
Typical values are ꢀ 0.275 and 0.215 ppm. Confirmation of the structure

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Genistein Derivatives
Table 2. Acylation of silylated genistein derivatives 2, 3, 4, and 11.
4115
Acylating
reagent
Reaction
time (h)
Yield
(%)
Entry
1
Substrate
Product
4
(AcO)2O
(2 equiv.)
24
5
7
62
30
55
2
4
(AcO)2O
(4 equiv.)
20
5
7
27
85
3
4
4
4
(AcO)2O
(4 equiv.)
AcCl
96
24
5
8
5
49
(4 equiv.)
12
64
5
6
4
4
(BzO)2O
(2 equiv.)
BzCl
24
24
11
10
12
51
(4 equiv.)
29
45
7
8
9
4
Phthalic anh.
(4 equiv.)
(AcO)2O
(4 equiv.)
AcCl
96
24
24
3
2 (15% of 3)
2 (15% of 3)
A mixture
of acetylated 1
—
80
9
7
(2 equiv.)
11
82
10
11
3
(AcO)2O
(4 equiv.)
(AcO)2O
(3 equiv.)
96
24
5
11
13
51
of compound 3 was provided equivocally by X-ray crystallographic
analysis (Fig. 2).[12]
Outcomes of acetylation reactions of both monosilylated derivatives
of genistein with acetic anhydride differ dramatically. Thus 3 gave
product 5, whereas acetylation of 2 resulted in desilylation followed by
esterification, providing a mixture of di- and tri-O-acetyl derivatives.
Quite remarkably, the 7-O-silyl group in 2 can be exchanged or retained,
depending on choice of the acetylating reagent. Thus, acetylation of
2 with acetyl chloride afforded derivative 9 in a good yield.

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4116
Szeja et al.
Me
Si
Me
7
O
5
HO
7
t
Bu
OH
O
genistein
5
HO
genistein
OH
t
4'
Bu
2
and
Si
4'
Me
Me
3
3 as a minor product
TBDMS (1equiv.)
imidazole, DMF
Phthalic anhydride (4 equiv.)
pyridine
Me
Me
7
7
OH
TBDMS (2 equiv.)
imidazole, DMF
O
O
Si
5
HO
5
HO
t
t
Bu
genistein
genistein
Bu
OH
Si
4'
4'
1
Me
4
Me
(AcO) O (4 equiv.)
2
pyridine
7
7
OAc
OAc
OH
Bu NF, THF
4
5
5
t
AcO
genistein
Bu
AcO
genistein
O
Si
4'
4'
5
6
Me
Me
Scheme 1.
Figure 2. X-ray structure of 3.
In summary, although direct selective monosilylation of genistein
proved rather difficult to achieve under standard conditions, it has been
demonstrated that complete differentiation of all three phenolic groups
in 1 is possible, in a stepwise manner, via 7,40-di-O-silyl derivative 4.

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Genistein Derivatives
4117
The described direct and regioselective transformation of 7-O-silyl group
under treatment of 4 with acyl anhydrides in pyridine, is to our knowledge,
without a precedent. It is worth noting that this new transformation opens
a simple way for the preparation of various selectively substituted
derivatives of genistein.
EXPERIMENTAL
Elemental analyses were performed on a Perkin–Elmer 2400 analyzer.
1H NMR spectra were recorded for solutions in CDCl3, or (CD3)2SO
(internal Me4Si) on Varian 300 MHz spectrometer. Melting points
were determined in capillaries and are uncorrected. Reactions were
monitored by TLC on precoated plates of silica gel 60 (70–230 mesh,
Merck), components were indicated with ultraviolet light after heating.
Chromatographic purification was performed on silica gel 60, Merck
(0.063–0.2 mm).
Silylation of Genistein (1)
Imidazole (2.72 g, 40 mmol) and tert-butyldimethylsilyl chloride
(3.3 g, 22 mmol) were added to a solution of genistein 1 (2.7 g,
10 mmol) in anhydrous DMF (30 mL). The mixture was stirred for
1.5 h at room temperature. Then the reaction mixture was diluted with
toluene (200 mL) and washed with water (2 ꢀ 50 mL). The water layer
was additionally extracted with methylene chloride (50 mL). All organic
extracts were dried (magnesium sulfate), filtered, and concentrated under
diminished pressure. Purification by column chromatography (hexane/
ethyl acetate, 20:1, v/v) of the resulting yellow solid (5.34 g) gave product
4 (4.19 g, 84% yield) and mixture of 2 and 3 (0.26 g, 6% yield).
7-t-Butyldimethylsilyloxy-5-hydroxy-3-(40-hydroxyphenyl)-chromen-
4-one (2). 1H NMR (CDCl3) ꢀ: 0.28 (s, 6H, CH3), 0.99 (s, 9H, (CH3)3C),
5.29 (s, 1H, 40-OH), 12.92 (s, 1H, 5-OH).
5,7-Dihydroxy-3-[40-(t-butyldimethylsilyloxy)phenyl]-chromen-4-one
(3). Yellow crystals. M.p.: 199–201ꢁC. Anal. calcd. for C21H24O5Si
(384.50): C, 65.60; H, 6.29. Found: C, 65.45; H, 6.27. 1H NMR (CDCl3)
ꢀ: 0.22 (s, 6H, CH3), 0.99 (s, 9H, (CH3)3C), 6.03 (s, 1H, 7-OH), 12.92
(s, 1H, 5-OH).
7-t-Butyldimethylsilyloxy-5-hydroxy-3-[40-(t-butyldimethylsilyloxy)-
phenyl]-chromen-4-one (4). Yellow crystals. M.p.: 86–88ꢁC. Anal.
calcd. for C27H38O5Si2 (498.76): C, 65.02; H, 7.68. Found: C, 65.17;

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4118
Szeja et al.
1
H, 7.42. H NMR (CDCl3) ꢀ 0.23 (s, 6H, CH3), 0.28 (s, 6H, CH3), 0.99
(s, 18H, (CH3)3C), 6.31 (d, 1H, H-6, J ¼ 2.2 Hz), 6.35 (d, 1H, H-8,
J ¼ 2.2 Hz), 6.91 (d, 2H, H-30, H-50, J ¼ 8.6 Hz), 7.39 (d, 2H, H-20,
H-60, J ¼ 8.6 Hz), 7.86 (s, 1H, H-2), 12.82 (s, 1H, 5-OH).
General Procedures for the Acylation
Procedure A
Acyl anhydride:acetic, benzoic, or phthalic (2–4 equiv. as listed in
Table 2) was added to a solution of genistein derivative 2, 3, 4, or 11
(2 mmol) in anhydrous pyridine (5 mL). The mixture was stirred for
20–96 h at room temperature (as listed in Table 2). The reaction mixture
was then diluted with toluene (30 mL) and washed with cold water
(3 ꢀ 15 mL). Organic layer was dried (magnesium sulfate), filtered and
concentrated under diminished pressure. The resulting solid was chroma-
tographed on a column of silica gel (hexane/ethyl acetate, 15:1, v/v). The
following compounds were obtained:
7-Acetoxy-5-acetoxy-3-[40-(t-butyldimethylsilyloxy)phenyl]-chromen-
4-one (5). White crystals. M.p.: 126–128ꢁC. Anal. calcd. for C25H28O7Si
(468.57): C, 64.08; H, 6.02. Found: C, 64.16; H, 6.25. 1H NMR (CDCl3)
ꢀ: 0.21 (s, 6H, CH3), 0.99 (s, 9H, (CH3)3C), 2.34 (s, 3H, CH3CO), 2.42
(s, 3H, CH3CO), 6.84 (d, 1H, H-8, J ¼ 2.4 Hz), 6.87 (d, 2H, H-30, H-50,
J ¼ 8.6 Hz), 7.23 (d, 1H, H-6, J ¼ 2.4 Hz), 7.34 (d, 2H, H-20, H-60,
J ¼ 8.6 Hz), 7.85 (s, 1H, H-2).
7-Acetoxy-5-hydroxy-3-[40-(t-butyldimethylsilyloxy)phenyl]-chromen-
4-one (7). Light yellow crystals. M.p.: 145–147.5ꢁC. Anal. calcd. for
C23H26O6Si (426.53): C, 64.77; H, 6.14. Found: C, 64.48; H, 6.02.
1H NMR (CDCl3) ꢀ: 0.23 (s, 6H, CH3), 1.00 (s, 9H, (CH3)3C), 2.33 (s,
3H, CH3CO), 6.58 (d, 1H, H-6, J ¼ 2.2 Hz), 6.75 (d, 1H, H-8,
J ¼ 2.2 Hz), 6.92 (d, 2H, H-30, H-50, J ¼ 8.6 Hz), 7.40 (d, 2H, H-20, H-
60, J ¼ 8.6 Hz), 7.94 (s, 1H, H-2), 12.85 (s, 1H, 5-OH).
7-Benzoyloxy-5-hydroxy-3-[40-(t-butyldimethylsilyloxy)phenyl]-chromen-
4-one (11). Light yellow crystals. M.p.: 164–166ꢁC. Anal. calcd. for
C28H28O6Si (488.60): C, 68.83; H, 5.78. Found: C, 68.99; H, 5.54.
1H NMR (CDCl3) ꢀ: 0.23 (s, 6H, CH3), 1.00 (s, 9H, (CH3)3C), 6.71 (d, 1H,
H-6, J ¼ 2.0 Hz), 6.87 (d, 1H, H-8, J ¼ 2.0Hz), 6.92 (d, 2H, H-30, H-50,
J ¼ 8.4Hz), 7.41 (d, 2H, H-20, H-60, J ¼ 8.4 Hz), 7.51 (m, 2H, m-C6H5),
7.65 (m, 1H, p-C6H5), 7.94 (s, 1H, H-2), 8.18 (m, 2H, o-C6H5), 12.89
(s, 1H, 5-OH).

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Genistein Derivatives
4119
7-Benzoyloxy-5-acetoxy-3-[40-(t-butyldimethylsilyloxy)phenyl]-chromen-
4-one (13). White crystals. M.p.: 117–120ꢁC. Anal. calcd. for C30H30O7Si
(530.64): C, 67.90; H, 5.70. Found: C, 68.28; H, 6.07. 1H NMR (CDCl3) ꢀ:
0.22 (s, 6H, CH3), 1.00 (s, 9H, (CH3)3C), 2.44 (s, 3H, CH3CO), 6.89 (d, 2H,
H-30, H-50, J ¼ 8.8 Hz), 6.99 (d, 1H, H-6, J ¼ 2.2 Hz), 7.36 (m, 3H, H-8,
H-20, H-60), 7.55 (m, 2H, m-C6H5), 7.69 (m, 1H, p-C6H5), 7.88 (s, 1H, H-2),
8.20 (m, 2H, o-C6H5).
Procedure B
Acyl chloride: acetyl or benzoyl (2–4 equiv. as listed in Table 2) was
added to a solution of genistein derivative 2 or 4 (2 mmol) in anhydrous
pyridine (5 mL). The mixture was stirred for 24 h at room temperature.
The reaction mixture was then diluted with toluene (30 mL) and washed
with cold water (3 ꢀ 15 mL). Organic layer was dried (magnesium
sulfate), filtered, and concentrated under diminished pressure. The resul-
ting solid was chromatographed on a column of silica gel (hexane/ethyl
acetate, 15:1, v/v). The following compounds were obtained:
7-t-Butyldimethylsilyloxy-5-acetoxy-3-[40-(t-butyldimethylsilyloxy)-
phenylo]-chromen-4-one (8). White crystals. M.p.: 91–94ꢁC. Anal.
calcd. for C29H40O6Si2 (540.80): C, 64.41; H, 7.46. Found: C, 64.67;
H, 7.39. 1H NMR (CDCl3) ꢀ: 0.21 (s, 6H, CH3), 0.28 (s, 6H, CH3), 0.99
(s, 18H, (CH3)3C), 2.41 (s, 3H, CH3CO), 6.53 (d, 1H, H-6, J ¼ 2.4 Hz),
6.74 (d, 1H, H-8, J ¼ 2.4 Hz), 6.86 (d, 2H, H-30, H-50, J ¼ 8.6 Hz), 7.33
(d, 2H, H-20, H-60, J ¼ 8.6 Hz), 7.78 (s, 1H, H-2).
7-t-Butyldimethylsilyloxy-5-hydroxy-3-(40-acetoxyphenyl)-chromen-
4-one (9). Light yellow crystals. M.p.: 119–121ꢁC. Anal. calcd. for
C23H26O6Si (426.53): C, 64.77; H, 6.14. Found: C, 64.60; H, 6.28.
1H NMR (CDCl3) ꢀ: 0.27 (s, 6H, CH3), 0.99 (s, 9H, (CH3)3C), 2.32
(s, 3H, CH3CO), 6.32 (d, 1H, H-6, J ¼ 2.4 Hz), 6.36 (d, 1H, H-8,
J ¼ 2.0 Hz), 7.16 (d, 2H, H-30, H-50, J ¼ 8.6 Hz), 7.54 (d, 2H, H-20,
H-60, J ¼ 8.6 Hz), 7.88 (s, 1H, H-2), 12.73 (s, 1H, 5-OH).
7-t-Butyldimethylsilyloxy-5-benzoyloxy-3-[40-(t-butyldimethylsilyloxy)
phenyl]-chromen-4-one (10). White crystals. M.p.: 148–152ꢁC. Anal.
calcd. for C34H42O6Si2 (602.86): C, 67.74; H, 7.02. Found: C, 68.32; H,
1
7.39. H NMR (CDCl3) ꢀ: 0.17 (s, 6H, CH3), 0.30 (s, 6H, CH3), 0.96 (s,
9H, (CH3)3C), 1.01 (s, 9H, (CH3)3C), 6.65 (d, 1H, H-6, J ¼ 2.4 Hz), 6.78
(d, 1H, H-8, J ¼ 2.4 Hz), 6.80 (d, 2H, H-30, H-50, J ¼ 8.5 Hz), 7.30 (d, 2H,
H-20, H-60, J ¼ 8.5 Hz), 7.44-7.64 (m, 3H, m-C6H5, p-C6H5), 7.79 (s, 1H,
H-2), 8.22–8.26 (m, 2H, o-C6H5).

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4120
Szeja et al.
7-Benzoyloxy-5-benzoyloxy-3-[40-(t-butyldimethylsilyloxy)phenyl]-
chromen-4-one (12). White crystals. M.p.: 97–100ꢁC. Anal. calcd. for
C35H32O7Si (592.71): C, 70.92; H, 5.44. Found: C, 71.23; H, 5.11.
1H NMR (CDCl3) ꢀ: 0.17 (s, 6H, CH3), 0.97 (s, 9H, (CH3)3C), 6.83
(d, 2H, H-30, H-50, J ¼ 8.6 Hz), 7.11 (d, 1H, H-8, J ¼ 2.4 Hz), 7.33
(d, 2H, H-20, H-60, J ¼ 8.6 Hz), 7.42 (d, 1H, H-6, J ¼ 2.4 Hz),
7.47–7.71 (m, 6H, m-C6H5, p-C6H5), 7.88 (s, 1H, H-2), 8.20–8.28
(m, 4H, o-C6H5).
Desilylation of Genistein Derivative 5
Seventy-Five percent water solution of Bu4NF (0.53 mL, 1.6 mmol)
was added to a solution of genistein derivative 5 (0.8 g, 1.6 mmol) in THF
(20 mL). The mixture was stirred 2 min at room temperature. Then the
reaction mixture was diluted with methylene chloride (50 mL) and
washed with water (20 mL). Organic layer was dried (magnesium sulfate),
filtered, and concentrated under diminished pressure. Purification by
column chromatography (hexane/ethyl acetate, 5:1, v/v) of the resulting
solid gave product 6 (0.3 g, 53% yield) as white crystals.
5,7-Diacetoxy-3-(40-hydroxyphenyl)-chromen-4-one (6). White crys-
tals. M.p.: 189–192ꢁC. Anal. calcd. for C19H14O7 (354.31): C, 64.41; H,
1
3.98. Found: C, 64.18, H, 4.22. H NMR ((CD3)2SO) ꢀ: 2.28 (s, 3H,
CH3CO), 2.29 (s, 3H, CH3CO), 6.60 (d, 1H, H-6, J ¼ 2.4 Hz), 6.80 (d,
1H, H-8, J ¼ 2.4 Hz), 7.21 (d, 2H, H-30, H-50, J ¼ 8.6 Hz), 7.50 (d, 2H, H-
20, H-60, J ¼ 8.6 Hz), 8.36 (s, 1H, H-2), 11.19 (s, 1H, 40-OH).
ACKNOWLEDGMENT
Partial financial support of the State Committee for Scientific
Research (KBN, grant 4 T09A 075 23) is gratefully acknowledged.
REFERENCES
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Research Since 1986; Harborne, J.B., Ed.; Chapman and Hall:
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biological functions. In Comprehensive Natural Products Chemistry;
Barton, D.H.R., Nakanishi, K., Meth-Cohn, O., Eds.; Elsevier:
Amsterdam, 1999; Vol. 1, 773–824.

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Genistein Derivatives
4121
3. Dixon, R.A.; Ferreira, D. Genistein. Phytochemistry 2002, 60,
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including 1,2- and 1,3-diols. In Protective Groups in Organic
Synthesis; 2nd Ed.; John Wiley & Sons Inc.: New York,
Chichester, Brisbane, Toronto, Singapore, 1991; 114–148.
12. Crystallographic data for 3: C21H24O5Si, M ¼ 385.50, monoclinic,
space group P21/n, a ¼ 8.152(2), b ¼ 7.819(2), c ¼ 33.453(7) A,
ꢁ ¼ 92.25(3)ꢁ, U ¼ 2130.7(7) A3, Z ¼ 4, T ¼ 293(2) K, ꢂ(Mo-Ka) ¼
0.14 mmꢂ1, Dc ¼ 1.20, 2630 reflections measured, of which 2576
independent (Rint ¼ 0.1573) Rf ¼ 0.0560 [657 data Fo>4ꢃ(Fo)],
wR(F2) ¼ 0.1643, S ¼ 0.856. Largest residual density peak
(0.30 eAꢂ3) is located close to atom Si1 (0.33 A). Crystallographic
data for the structure reported in this article have been deposited
with the Cambridge Crystallographic Data Centre as deposition No.
CCDC 200812. Copies of the data can be obtained, free of charge,
on application to CCDC, 12 Union Road, Cambridge CB2 1EZ,
U.K. [Fax: þ44(0)1223 336033; E-mail: deposit@ccdc.cam.ac.uk].
Received in Poland April 17, 2003

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