Ugi multicomponent reaction product: The inhibitive effect on DNA oxidation depends upon the isocyanide moiety

Article abstract of DOI:10.1021/jo401426n

The hydroxyl-substituted benzoic acid (as phenyl group A in the product), aniline (as phenyl group B in the product), benzaldehyde (as phenyl group C in the product), and four isocyanides are employed to synthesize bis-amide via an Ugi four-component reaction. The effects of the obtained 20 bis-amides on quenching radicals and inhibiting DNA oxidation are estimated. It is found that the antioxidant effectiveness of bis-amide generated by hydroxyl groups is markedly influenced by the structural feature derived from isocyanide. The phenolic hydroxyl group attaching to phenyl group A plays a major role in scavenging radicals, and the radical-scavenging property is reinforced by the structural moiety introduced from ferrocenylmethyl isocyanide. The same conclusion is also obtained when bis-amides are used to inhibit DNA oxidation. It is still found that the ferrocenylmethyl moiety enhances the antioxidant effect of hydroxyl group at phenyl group A in protecting DNA against the oxidation. Moreover, when the bis-amide is prepared by the same isocyanide, e.g. ethyl isocyanoacetate, it is found that the hydroxyl group at phenyl group C plays the major role in inhibiting DNA oxidation, followed by the hydroxyl groups attaching to phenyl groups B and A.

Full text of DOI:10.1021/jo401426n

Article
pubs.acs.org/joc
Ugi Multicomponent Reaction Product: The Inhibitive Effect on DNA
Oxidation Depends upon the Isocyanide Moiety
Rui Wang and Zai-Qun Liu*
Department of Organic Chemistry, College of Chemistry, Jilin University, Changchun 130021, People’s Republic of China
S
* Supporting Information
ABSTRACT: The hydroxyl-substituted benzoic acid (as phenyl group A in the
product), aniline (as phenyl group B in the product), benzaldehyde (as phenyl
group C in the product), and four isocyanides are employed to synthesize bis-
amide via an Ugi four-component reaction. The effects of the obtained 20 bis-
amides on quenching radicals and inhibiting DNA oxidation are estimated. It is
found that the antioxidant effectiveness of bis-amide generated by hydroxyl groups
is markedly influenced by the structural feature derived from isocyanide. The
phenolic hydroxyl group attaching to phenyl group A plays a major role in
scavenging radicals, and the radical-scavenging property is reinforced by the
structural moiety introduced from ferrocenylmethyl isocyanide. The same
conclusion is also obtained when bis-amides are used to inhibit DNA oxidation.
It is still found that the ferrocenylmethyl moiety enhances the antioxidant effect of
hydroxyl group at phenyl group A in protecting DNA against the oxidation.
Moreover, when the bis-amide is prepared by the same isocyanide, e.g. ethyl isocyanoacetate, it is found that the hydroxyl group
at phenyl group C plays the major role in inhibiting DNA oxidation, followed by the hydroxyl groups attaching to phenyl groups
B and A.
application of Ugi-4CR for preparing molecules with various
properties is the largest field in the study of this method.
Special isocyanides are adopted in sequential Ugi-4CR for
producing peptides with biological17 or chemical activities18
and for producing novel topological structures.19 The
combination of various carboxylic acid, aldehyde, amine, and
isocyanide in the Ugi-4CR allows hundreds of bis-amides to be
formed for the sake of combinatorial screening drugs.20,21
The phenolic −OH is a well-known functional group for
generating antioxidant effectiveness.22 If hydroxyl-substituted
benzoic acid, benzaldehyde, aniline, and some isocyanides are
employed to carry out Ugi-4CR, the produced bis-amide is
suitable for being explored the mutual antioxidant effects
among phenolic hydroxyl groups at different positions. Reports
on the application of Ugi-4CR to construct antioxidants are not
usually found,23 and the influence of the isocyanide moiety on
antioxidant effectiveness remains unclear. As shown in Scheme
1, 20 bis-amides have been synthesized by using Ugi-4CR, and
the radical-scavenging properties have been compared by
quenching 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate)
cationic radical (ABTS•+), 2,2′-diphenyl-1-picrylhydrazyl radi-
cal (DPPH), and galvinoxyl radical, respectively.24 The
antioxidant effect has been evaluated by inhibiting the oxidation
of DNA mediated by 2,2′-azobis(2-amidinopropane hydro-
chloride) (AAPH). Mutual antioxidant effects among hydroxyl
INTRODUCTION
■
A fast-growing interest in multicomponent reactions (MCRs)
has been witnessed in recent years, because MCRs provide a
highly efficient approach for constructing polyfunctional
molecules from simple materials.1 The Ugi four-component
reaction (Ugi-4CR) is a convenient access to bis-amides with a
carboxylic acid, an amine, an aldehyde, and an isocyanide being
the starting materials.2 At present, the research of the Ugi-4CR
mainly follows three directions. Screening feasible substrates to
replace traditional reagents may be the first aspect in the
research of Ugi-4CR. The use of diamine,3 secondary amine,4
β-ketoamide,5 phenol,6 or enol7 to replace the primary amine
or carboxylic acid enlarge the applicability of the Ugi-4CR.
Also, elaborately selecting substrates and accurately controlling
reaction conditions permit even more than four components to
form a domino system8 or at least a cascade operation9 for
constructing complicated structures via a simple operation.10
The Ugi-4CR is found to be accelerated in water.11 A newly
theoretical calculation illustrates an overall downward trend for
the activation energy when the Ugi-4CR is carried out in
methanol and toluene.12 Thus, the Ugi-4CR is a self-catalyzed
reaction, in which catalysts seem to be not a necessary factor.
However, some catalysts are still applied to promote the post-
Ugi-4CR. For example, gold salt13 and palladium or copper
acetate14 trigger the annulation of Ugi-4CR products. Also,
asymmetric catalysts are used to promote enantioselective Ugi-
4CR,15 and an enzyme as catalyst agitates some inert reagents
to perform the Ugi-4CR.16 Hence, screening catalysts is the
second aspect in the investigation on the Ugi-4CR. Finally, the
Received: July 2, 2013
© XXXX American Chemical Society
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a
Scheme 1. Structures of Bis-Amides Employed in the Present Work
a
The isolation yields.
groups attaching to different benzenes as well as the influence
of isocyanide on the antioxidant effect have been investigated.
indicating that a phenolic hydroxyl group rather than N−H is
the active group reducing ABTS•+. Figure 2S (Supporting
Information) shows that only compounds 6−20 are able to
quench DPPH, while compounds 2−5 do not show any activity
in this case. Every phenyl group bearing one hydroxyl group
and the whole molecule containing three hydroxyl groups in
compound 5 still do not donate the hydrogen atom in −OH to
the N-centered radical. Figure 3S (Supporting Information)
illustrates that compounds 11−20 (except for compound 15)
can quench galvinoxyl radical. The common structural feature
in these compounds is an o-methoxyhydroxyl or 1,2,3-
trihydroxyl group at phenyl group A. However, in compounds
10 and 15 the o-methoxyhydroxyl group attaching to phenyl
group C cannot donate the hydrogen atom in −OH to the O-
centered radical. Thus, only the o-methoxyhydroxyl group
attaching to phenyl group A can be the active quenching the O-
centered radical. On the other hand, it is found that the
selectivity of radical resources employed to screen the radical-
scavenging properties of the bis-amides is galvinoxyl radical >
DPPH > ABTS•+.
RESULTS AND DISCUSSION
■
Scavenging Radicals. Scavenging radicals is regarded as
the primary property of an antioxidant.25 ABTS•+, DPPH, and
galvinoxyl radical are usually applied as a way to evaluate the
antioxidant ability to scavenge radicals. The reaction of an
antioxidant with ABTS•+ reveals the ability of the antioxidant to
reduce the radical, and reactions of the antioxidant with DPPH
and galvinoxyl radical exhibit the ability of the antioxidant to
donate its hydrogen atom to N- and O-centered radicals,
respectively. All bis-amides have been applied to quench
ABTS•+, DPPH, and galvinoxyl radical, respectively. The decays
of the concentrations for these radicals are included in the
Supporting Information (Figures 1S−3S). Some bis-amides
that do not reaction with the aforementioned radicals are
indicated by the symbol of “−” in Table 1.
All bis-amides used herein (except compound 1) decrease
the concentration of ABTS•+ at longer reaction times,
B
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simultaneously expressed by a double-exponential function.
The equations of [ABTS•+] ∼ t for every compound are given
in Table 1S (Supporting Information). Then, the differential
operation is performed with eq 3 in order to reveal the variation
of the reaction rate (r) with the reaction time (t),
−d[ABTS•+]/dt ∼ t (eq 4).
Table 1. Rate Constants (k) for Bis-Amides in Scavenging
ABTS+., DPPH, and Galvinoxyl Radical
rate constant for bis-amides to scavenge radicals, k (M−1 s−1
)
compd
ABTS•+
DPPH
galvinoxyl radical
1
_
_
_
_
_
_
_
2
13.0
_
d[ABTS•+
]
A
a
B
b
3
16.7
_
−
= r = e−t/a
+
e−t/b
4
1.08 × 102
67.3
_
(4)
dt
5
_
6
9.86 × 102
2.97 × 103
3.27 × 103
3.26 × 103
2.86 × 103
9.77 × 103
1.84 × 104
8.38 × 103
2.09 × 103
4.00 × 103
1.63 × 104
1.09 × 104
1.76 × 104
1.59 × 104
2.18 × 104
0.297
_
7
1.73
_
8
4.18
_
The reaction rate at t = 0 (r0) can be calculated following eq
4 when the reaction time (t) is assigned as 0. The rate constant
(k) is subsequently calculated by using eq 2. This method is
also used to treat data obtained from bis-amides quenching
other radicals, and the results are given in Table 1. Sometimes
the method of a pseudo-first-order reaction is a convenient way
to simplify the operation of the measurement of k. However, if
the concentration of either antioxidant or radical is high
enough, the reaction between the antioxidant and radical is so
fast that the variation for the compound with low concentration
is difficult to follow. The present method takes the
concentrations of both antioxidant and radical into consid-
eration simultaneously and thus avoids the inconvenient
operation derived from a pseudo-first-order reaction.
By the comparison of the rate constant (k) in quenching
ABTS•+, it is also found that ortho-methoxyhydroxyl group or
1,2,3-trihydroxyl groups attaching to phenyl group A increases
k values of compounds 11−13 and 16−20 to 104 magnitude,
while the o-methoxyhydroxyl group attached to phenyl group C
does not play the same role for compounds 7−10. For
quenching DPPH and galvinoxyl radical, k values of
compounds 12, 16, and 18 are higher than those of other
compounds, indicating that 1,2,3-trihydroxyl groups attaching
to phenyl group A are the major functional groups for
contributing the hydrogen atom in −OH to N- and O-centered
radicals. Furthermore, by the comparison of k values of
compounds 12, 16, and 18, it is found that the
ferrocenylmethyl group enhances the k value of compound
18 markedly when these compounds are used to donate
hydrogen atoms to N- and O-centered radicals (quenching
DPPH and galvinoxyl radical). However, in a comparison of
abilities of these compounds to reduce radical (quenching
ABTS•+), the ferrocenylmethyl group enhances the k value of
compound 18 not very remarkably. Hence, the hydrogen atom
donating ability is mainly due to the hydroxyl group attached to
phenyl group A and is reinforced by the ferrocenylmethyl group
derived from the corresponding isocyanide.
9
2.74
_
10
11
12
13
14
15
16
17
18
19
20
1.59
_
79.7
15.5
5.04 × 103
97.0
2.54 × 103
59.4
17.2
7.85
2.52
_
4.40 × 103
78.1
1.10 × 103
18.0
1.07 × 104
1.04 × 102
1.01 × 102
6.93 × 103
51.5
1.15 × 102
We have suggested a method for treating data obtained from
the interaction of a radical with an antioxidant.26 The reaction
between an antioxidant and ABTS•+ is taken as an example.
The rate constant (k) can be calculated following the chemical
kinetics equation (1) in the case of [ABTS•+], [antioxidant],
d[ABTS•+
]
−
= r = k[ABTS•+][antioxidant]
(1)
dt
and the corresponding reaction rate (r) at a certain time-point
being measured. Equation 1 is based on a previous report, in
which the elementary reaction between an antioxidant and
radical is regarded as a first-order reaction in every reagent.27
t
= 0 may be an appropriate time point because at [ABTS•+]t=0
and [antioxidant]t=0, the concentrations of the antioxidant and
ABTS•+ at the beginning of the reaction are known. As a result,
eq 1 becomes eq 2. The key problem focuses on how the
r0 = k[ABTS•+
]t=0[antioxidant]t=0
(2)
reaction rate at t = 0 (r0) can be obtained. Thus, the variation of
the concentration of ABTS•+ with the reaction time (t) should
be expressed. The measured concentration of ABTS•+
([ABTS•+]) and the corresponding time point (t) are input
into statistical software in order to find a function for expressing
the relationship of [ABTS•+] ∼ t. Consequently, the
exponential function (3) is found to be the suitable one.
Inhibiting AAPH-Induced Oxidation of DNA. The
decomposition of AAPH in the presence of oxygen at 37 °C
generates peroxyl radical for oxidizing the guanine bases in
DNA.28 The products from AAPH-induced oxidation of DNA
can be colorized after the reaction with thiobarbituric acid, and
thus the determination of thiobarbituric acid reactive species
(TBARS, λmax 535 nm, εTBATS = 1.56 × 105 M−1 cm−1)
becomes a convenient way to follow the process of DNA
oxidation.29 As shown in Figure 1, a continual increase of the
absorbance in the blank experiment ([bis-amide] = 0 μM)
indicates that much more TBARS is generated for longer
reaction times. Thus, the variation of the concentration of
TBARS with the reaction period (t) can be linearly fitted by eq
5. The differential operation on eq 5, d[TBARS]/dt = 6.8 nM·
[ABTS•+] = Ae−t/a + Be−t/b + C
(3)
Although other functions may also be perfectly fitted for the
experimental data, the double-exponential function as shown in
eq 3 implies that every item (either the antioxidant or the
radical) is expressed by a single-exponential function because
the antioxidant and the radical are first order in the reaction,
respectively, and the antioxidant and the radical are
C
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As shown in Figure 2, the antioxidant effects of other bis-
amides are higher than those of the aforementioned species
Figure 2. Increase of TBARS absorbance in a mixture of 40 mM
AAPH and 2.24 mg mL−1 DNA with the reaction period in the
presence of various concentrations of compound 6 (A) and the
relationship between tinh and the concentration of compound 6 (B).
Figure 1. Increase of TBARS absorbance in a mixture of 40 mM
AAPH and 2.24 mg mL−1 DNA with the reaction period in the
presence of 200 μM compound 2.
because these bis-amides can inhibit the formation of TBARS
for a period. When compound 6 is taken as an example, it is
found that the inhibition period (tinh) can be measured from the
beginning of the reaction to the cross point of tangents for the
inhibition and oxidation periods. This method for obtaining tinh
is derived from the measurement of the same parameter in
recording the oxygen-exhausting process of a radical-induced
oxidation of polyunsaturated fatty acid. The cross point of
tangents for the inhibition and the oxidation period is assigned
to tinh.30 Herein the experimental data from the measurement of
TBARS are individual points and not a successive line as in the
recording of the oxygen-exhausting process. The data of
TBARS concentration are fitted by the Boltzmann function to
form a successive line, and then the tinh value can be obtained
from the cross point of tangents.31 As shown in Figure 2A, tinh
increases with the concentration of compound 6 employed, and
the linear relationship is illustrated in Figure 2B. As shown in
Figure 5S and 6S (Supporting Information), tinh generated by
compounds 7−10, 12, 13, and 15−20 in inhibiting DNA
oxidation correlates linearly with concentrations of these
compounds, and the linear equations of tinh ∼ [bis-amide] are
given in Table 3.
min−1, expresses the formation rate of TBARS in the blank
experiment of AAPH-induced oxidation of DNA.
[TBARS (nM)] = [6.8( 0.3)]t (min) + 3267( 173)
(5)
The addition of compound 1 (200 μM) does not affect the
increase of TBARS (see Figure 4S in the Supporting
Information) because d[TBARS]/dt in the presence of
compound 1 is 7.0 nM min−1, similar to that in the blank
experiment (d[TBARS]/dt = 6.8 nM min−1). Hence, bis-amide
cannot inhibit the DNA oxidation without the aid of the
phenolic hydroxyl group. Moreover, additions of compounds
2−4, 5, 11, and 14 (200 μM) obviously slow down the increase
of TBARS (the linear relationships of [TBARS] ∼ t are given in
Table 4S in the Supporting Information), demonstrating that
these compounds can protect DNA against AAPH-induced
oxidation. Moreover, d[TBARS]/dt values in the presence of
these compounds are collected in Table 2. The lowest value of
Table 2. Formation Rate of TBARS (d[TBARS]/dt)
It has been proved that tinh correlates proportionally with
compd
d[TBARS]/dt (nM min−1
)
concentration of the antioxidant, as shown in eq 6.32
blank
1
6.8
7.0
2.9
4.7
3.6
0.6
4.8
5.3
tinh = (n/Ri)[antioxidant]
(6)
2
3
In this equation, Ri is the initiation rate of the radical-induced
reaction, and the stoichiometric factor (n) refers to the number
of radicals trapped by one molecule of the antioxidant. It is
assumed that Ri is equal to the generation rate (Rg) of radicals
(Rg = ((1.4 0.2) × 10−6)[AAPH] s−1)32 because AAPH and
the sodium salt of DNA are both water-soluble substances, and
radicals produced by AAPH attacked DNA at the same phase.
Hence, Ri can be calculated by Ri = Rg = (1.4 × 10−6) × 40 mM
s−1 = 3.36 μM·min−1. The n value is a quantitative index for
estimating the antioxidant effectiveness.33 Accordingly, the n
values of bis-amides are calculated and given in Table 3. In
order to explore the structure−activity relationship, the n values
and the corresponding structure of bis-amides are illustrated in
Figure 3.
4
5
11
14
d[TBARS]/dt of compound 5 indicates that hydroxyl groups at
different benzenes exhibit relatively high activity in inhibiting
DNA oxidation. This is quite different from the result of
trapping DPPH and galvinoxyl radical, in which compound 5
does not show any activity. The values of d[TBARS]/dt of
compound 2 (hydroxyl group at phenyl group C), 3 (hydroxyl
group at phenyl group A), and 4 (hydroxyl group at phenyl
group B) follows the order 2 < 4 < 3, implying that the position
of hydroxyl group influences antioxidant effectiveness follows
the order of phenyl groups C > B > A.
The first panel in Figure 3 shows the results from
compounds 14, 11, 17, and 19, which have the same structures
D
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compound 8, increases the n value to 2.87. However, the
addition of a hydroxyl group to phenyl group B of compound 7,
giving compound 9, increases the n value to 4.40. If another
hydroxyl group attaches to phenyl group A of compound 9,
giving compound 10, the n value of compound 10 only
increases to 4.64. Thus, hydroxyl groups at phenyl group C and
then B play the major roles in protecting DNA against AAPH-
induced oxidation. As shown in Scheme 2, the conformations of
compounds 11, 14, and 17 are calculated at the B3LYP/6-
31g(d) level at the same zero vibration energy. The carbon
chain exhibits a linear structure in the molecule of bis-amide,
where phenyl groups B and C form a dihedral angle, and phenyl
group A and the structural moiety from isocyanide are located
at the two tips of the molecule. Hence, hydroxyl groups
attaching to phenyl group A and the isocyanide moiety play a
mutual antioxidant role over a long distance, while hydroxyl
groups attaching to phenyl groups B and C play the same role
over a dihedral angle.
Table 3. Linear Equations between Inhibition Period (tinh)
and Concentrations of Bis-Amides in AAPH-Induced
a
Oxidation of DNA
compd
tinh (min) =(n/Ri)[concentration (μM)]
n
6
tinh = 0.57( 0.03) [6] + 104.6( 5.3)
tinh = 0.48( 0.02) [7] + 108.4( 5.4)
tinh = 0.79( 0.04) [8] + 57.4( 2.9)
tinh = 1.31( 0.06) [9] + 57.4( 3.3)
tinh = 1.38( 0.07) [10] + 24.6( 1.2)
tinh = 0.46( 0.02) [12] + 20.4( 1.0)
tinh = 1.16( 0.06) [13] + 59.0( 2.9)
tinh = 1.38( 0.07) [15] + 42.2 ( 2.1)
tinh = 0.48( 0.02) [16] + 27.7( 1.4)
tinh = 0.47( 0.02) [17] + 36.8( 1.8)
tinh = 4.24( 0.21) [18] − 26.2( 1.3)
tinh = 3.44( 0.17) [19] − 5.67( 0.3)
tinh = 2.56( 0.13) [20] + 53.9( 2.7)
1.93( 0.09)
1.61( 0.08)
2.87( 0.14)
4.40( 0.22)
4.64( 0.23)
1.56( 0.08)
3.90( 0.19)
4.64( 0.23)
1.61( 0.08)
1.58( 0.08)
14.24( 0.71)
11.56( 0.58)
8.60( 0.43)
7
8
9
10
12
13
15
16
17
18
19
20
a
The value of n is the product of the coefficient of tinh ∼ [bis-amides]
and Ri = (1.4 × 10−6) × 40 mM s−1 = 3.36 μM min−1 when 40 mM
AAPH is employed.
CONCLUSION
■
Ugi-4CR provides a powerful tool for integrating phenolic
hydroxyl groups within one bis-amide molecule, which is
suitable for exploring the mutual antioxidant effects among
phenolic hydroxyl groups attached to different parts of the
molecule. It is actually found that the antioxidant property of
the phenolic hydroxyl group at one tip of the molecule depends
upon the isocyanide moiety at another tip of the molecule, in
which ferrocenylmethyl isocyanide enhances the antioxidant
effect markedly. Thus, the isocyanide moiety influences the
antioxidant effect of the hydroxyl group via a long distance
within a molecule. Mutual antioxidant effectiveness is also
found among phenolic hydroxyl groups at adjacent benzenes.
The present finding provides novel information on the
structure−activity relationship for antioxidant design.
at phenyl groups A−C. Compounds 14 and 11 do not generate
an n value, while the n value of compound 17 is 1.58 and that of
compound 19 promptly increases to 11.56. Thus, the structural
moieties derived from benzophenonyl and ethoxycarbonyl
isocyanides are not able to improve the antioxidant
effectiveness derived for the phenyl group A, a ferulic acid
moiety. In contrast, it can be regarded that the structural moiety
derived from tert-butyl isocyanide causes compound 17 to
generate an n value of 1.58, and the use of ferrocenylmethyl
isocyanide remarkably enhances the n value of compound 19 to
11.56. Moreover, the same conclusion can be drawn by
observing the second panel in Figure 3. The n values of
compounds 12, 16, and 18 are 1.56, 1.61, and 14.24,
respectively. The antioxidant effects of these compounds are
definitely generated by 1,2,3-trihydroxyl groups attached to
phenyl group A. The highest n value for compound 18 (14.24)
indicates that this compound possesses the highest antioxidant
ability that undoubtedly correlates with the ferrocenylmethyl
group. As can be seen from the last panel in Figure 3, the n
value of compound 20 (8.60) is higher than that of compound
13 (3.90), while compounds 10 and 15 have the same n value
(both 4.64), and compounds 12 and 16 possess similar n values
(1.56 and 1.61, respectively). The aforementioned results reveal
that the increasing effect of the isocyanide moiety on the
antioxidant property follows the sequence ferrocenylmethyl
group > tert-butyl group > ethoxycarbonyl group >
benzophenonyl group. Furthermore, as shown as the last
panel in Figure 3, a comparison of the n values of compounds
7−9 reveals the influence of hydroxyl groups at phenyl groups
B and C on the antioxidant effectiveness, because the structures
of phenyl group A and the ethoxycarbonyl group are the same
in these compounds. In compound 7 the phenyl group C is a
vanillylidene group, in which the 4-hydroxyl-3-methoxyl group
is the functional group for generating antioxidant effectiveness.
Hence, the n value of compound 7 (1.61) is attributed to the
vanillylidene group. The n value of compound 6 (1.93) is
higher than that of compound 7 (1.61), indicating that the
ability of the 4-hydroxyl-3-methoxyl group to generate an
antioxidant effect is lower than that of 2,4-dihydroxyl groups at
the same position (phenyl group C). The addition of a
hydroxyl group to the phenyl group A of compound 7, giving
EXPERIMENTAL SECTION
■
Materials and Instrumentation. ABTS, DPPH, and galvinoxyl
radical were purchased from Fluka Chemie GmbH, Switzerland, and
AAPH and naked DNA sodium salt were purchased from Acros
Organics, Belgium. Ferrocenylmethyl isocyanide was synthesized by
following a literature procedure.34 Other reagents were of analytical
grade and were used directly. The structures of the obtained products
were identified by 1H and 13C NMR, and the spectral data are included
in the Supporting Information.
General Synthetic Procedure. The bis-amides were synthesized
following a literature procedure.35 Briefly, a methanol solution (3 mL)
of aldehyde (2 mmol) and amine (2 mmol) was stirred at room
temperature for 1 h, followed by adding carboxylic acid (2 mmol) and
isocyanide (2 mmol). The reaction mixture was stirred for 24 h at
room temperature, and the solvent was removed under vacuum. The
residual solid was purified by recrystallization or column chromatog-
raphy on silica gel to afford products.
Ethyl 2-[2-Phenyl-2-(N-phenylbenzamido)acetamido]acetate (1).
Purified by column chromatography with petroleum ether and ethyl
1
acetate as eluent. Yield: 582.4 mg, 75%. Mp: 132−133 °C. H NMR
(400 MHz, DMSO-d6): δ 1.19 (t, 3H, CH3 of Et), 3.80−4.02 (m, 2H,
CH2 of Et), 4.11 (d, J = 7.2 Hz, 2H, CH2), 6.42 (s, 1H, CH), 6.91 (s,
3H, aromatic), 7.00 (s, 2H, aromatic), 7.15−7.21 (m, 10H, aromatic),
8.63 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6): δ 14.1, 41.1, 60.4,
63.9, 126.7, 127.5, 127.7, 127.7, 127.9, 129.0, 130.5, 130.8, 134.8,
136.7, 140.2, 169.6, 169.9, 170.0.
Ethyl 2-[2-(4-Hydroxyphenyl)-2-(N-phenylbenzamido)-
acetamido]acetate (2). Recrystallization from C2H5OH/H2O. Yield:
1
717 mg, 83%. Mp: 190−193 °C. H NMR (300 MHz, DMSO-d6): δ
1.19 (t, 3H, CH3 of Et), 3.76−4.05 (m, 2H, CH2 of Et), 4.06−4.13 (q,
J = 6.9 Hz, 2H, CH2), 6.30 (s, 1H, CH), 6.51 (d, J = 8.4, 2H,
E
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Figure 3. Relationship between the structure of bis-amides and stoichiometric factor (n).
aromatic), 6.94−7.20 (m, 12H, aromatic), 8.50 (s, 1H, NH), 9.33 (s,
1H, OH). 13C NMR (75 MHz, DMSO-d6): δ 14.1, 41.1, 60.4, 63.5,
114.6, 124.9, 126.6, 127.5, 127.7, 127.9, 128.9, 131.0, 131.8, 140.3,
169.7, 169.8, 170.5.
Ethyl 2-[2-(4-Hydroxy-N-phenylbenzamido)-2-phenyl-
acetamido]acetate (3). Purified by column chromatography with
petroleum ether and ethyl acetate as eluent. Yield: 752 mg, 87%. Mp:
145−147 °C. 1H NMR (300 MHz, DMSO-d6): δ 1.19 (t, 3H, CH3 of
Et), 3.79−3.99 (m, 2H, CH2 of Et), 4.07−4.14 (q, J = 6.9 Hz, 2H,
CH2), 6.41 (s, 1H, CH), 6.49 (d, J = 7.2, 2H, aromatic), 6.30 (s, 5H,
aromatic), 7.07 (d, J = 6.9, 2H, aromatic), 7.16 (s, 5H, aromatic), 8.60
(t, 1H, NH), 9.70 (s, 1H, NH). 13C NMR (75 MHz, DMSO-d6): δ
F
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Scheme 2. Conformations of Compounds 11, 14, and 17 Calculated at the B3LYP/6-31g(d) Level
14.1, 41.1, 60.4, 64.1, 114.2, 126.4, 126.8, 127.6, 127.8, 127.9, 128.0,
130.5, 130.6, 135.1, 141.0, 158.3, 169.7, 169.7, 170.2.
NMR (300 MHz, DMSO-d6): δ 1.18 (t, 3H, CH3 of Et), 3.57 (s, 3H,
OCH3), 3.74−4.04 (m, 2H, CH2 of Et), 4.05−4.12 (m, 2H, CH2),
6.21 (s, 1H, CH), 6.31 (d, J = 7.8, 2H, aromatic), 6.55−6.63 (m, 4H,
aromatic), 7.18 (d, J = 3.0, 6H, aromatic), 8.42 (t, 1H, NH), 8.91 (s,
1H, OH), 9.24 (s, 1H, OH). 13C NMR (75 MHz, DMSO-d6): δ 13.9,
40.9, 55.2, 60.2, 63.6, 114.1, 114.5, 114.9, 123.4, 125.3, 127.3, 127.7,
128.6, 131.3, 132.0, 137.1, 145.9, 146.6, 155.5, 169.6, 169.8, 170.4.
Ethyl 2-[2-(4-Hydroxy-3-methoxyphenyl)-2-(4-hydroxy-N-(4-
hydroxyphenyl)benzamido)acetamido]acetate (10). Recrystalliza-
tion from C2H5OH/H2O. Yield: 533 mg, 54%. Mp: 165−167 °C
dec. 1H NMR (300 MHz, DMSO-d6): δ 1.18 (t, 3H, CH3 of Et), 3.54
(s, 3H, OCH3), 3.74−4.05 (m, 2H, CH2 of Et), 4.06−4.13 (m, 2H,
CH2), 6.27 (s, 1H, CH), 6.47−6.64 (m, 5H, aromatic), 6.98−7.04 (d,
6H, aromatic), 7.01 (s, 1H, OH), 8.45 (t, 1H, NH), 8.89 (s, 1H, OH),
9.67 (s, 1H, OH). 13C NMR (75 MHz, DMSO-d6): δ 19.5, 46.5, 60.8,
65.8, 69.3, 119.6, 120.1, 120.3, 128.9, 130.1, 131.8, 132.5, 133.1, 135.9,
136.3, 146.5, 151.5, 152.2, 163.6, 175.0, 175.2, 176.1.
(E)-Ethyl 2-[2-(3-(4-Hydroxy-3-methoxyphenyl)-N-phenylacryla-
mido)-2-phenylacetamido]acetate (11). Purified by column chro-
matography with petroleum ether and ethyl acetate as eluent. Yield:
478 mg, 49%. Mp: 195−197 °C dec. 1H NMR (300 MHz, DMSO-d6):
δ 1.18 (t, 3H, CH3 of Et), 3.68 (s, 3H, OCH3), 3.77−4.02(m, 2H, CH2
of Et), 4.05−4.13 (q, J = 6.9, 2H, CH2), 5.93 (d, J = 15.0, 1H, CH
CH), 6.34 (s, 1H, CH), 6.71 (s, 2H, aromatic), 6.86 (s, 1H, aromatic),
7.13 (s, 6H, aromatic), 7.18 (s, 4H, aromatic), 7.50 (d, J = 15.3, 1H,
CHCH), 8.59 (t, 1H, NH), 9.46 (s, 1H, OH). 13C NMR (75 MHz,
DMSO-d6): δ 14.1, 41.1, 55.6, 60.4, 63.5, 112.0, 115.9, 116.2, 120.8,
126.2, 127.6, 127.7, 127.8, 128.4, 130.5, 131.0, 135.1, 139.4, 141.6,
147.7, 148.6, 165.5, 169.7, 170.3.
Ethyl 2-[2-(N-(4-Hydroxyphenyl)benzamido)-2-phenyl-
acetamido]acetate (4). Purified by column chromatography with
petroleum ether and ethyl acetate as eluent. Yield: 691 mg, 80%. Mp:
165−166 °C. 1H NMR (300 MHz, DMSO-d6): δ 1.19 (t, 3H, CH3 of
Et), 3.78−4.00 (m, 2H, CH2 of Et), 4.06−4.14 (q, J = 6.9 Hz, 2H,
CH2), 6.27 (d, J = 8.1, 2H, aromatic), 6.34 (s, 1H, CH), 6.77 (s, 1H,
aromatic), 7.19 (d, J = 7.2, 11H, aromatic), 8.53 (t, 1H, NH), 9.23 (s,
1H, OH). 13C NMR (75 MHz, DMSO-d6): δ 14.1, 41.1, 60.4, 63.9,
114.3, 127.4, 127.6, 127.7, 127.9, 128.8, 130.6, 131.3, 131.9, 135.0,
137.0, 155.6, 169.7, 170.1, 171.0.
Ethyl 2-[2-(4-Hydroxy-N-(4-hydroxyphenyl)benzamido)-2-(4-
hydroxyphenyl)acetamido]acetate (5). Recrystallization from
C2H5OH/H2O. Yield: 687 mg, 74%. Mp: 212−214 °C dec. 1H
NMR (400 MHz, DMSO-d6): δ1.18 (s, 3H, CH3 of Et), 3.76−3.98
(m, 2H, CH2 of Et), 4.09 (s, 2H, CH2), 6.19 (s, 1H, CH), 6.33 (s, 2H,
aromatic), 6.51 (t, 5H, aromatic), 6.71 (s, 1H, aromatic), 6.90 (d, J =
5.2 Hz, 2H, aromatic), 7.04 (d, J = 5.2 Hz, 2H, aromatic), 8.37 (s, 1H,
NH), 9.23 (s, 1H, OH), 9.31 (s, 1H, OH), 9.64 (s, 1H, OH). 13C
NMR (100 MHz, DMSO-d6): δ 14.1, 41.1, 60.4, 63.9, 114.1, 114.4,
114.6, 125.5, 127.3, 130.4, 131.8, 131.9, 132.2, 155.5, 156.7, 158.1,
169.8, 170.7.
Ethyl 2-[2-(2,4-Dihydroxyphenyl)-2-(N-phenylbenzamido)-
acetamido]acetate (6). Recrystallization from C2H5OH/H2O. Yield:
1
457 mg, 51%. Mp: 144−146 °C. H NMR (300 MHz, DMSO-d6): δ
1.20 (t, 3H, CH3 of Et), 3.72−4.05 (m, 2H, CH2 of Et), 4.07−4.14 (q,
J = 6.9 Hz, 2H, CH2), 5.86 (d, J = 8.4, 1H, aromatic) 6.14 (s, 1H, CH),
6.45 (s, 1H, aromatic), 6.65 (d, J = 8.4, 1H, aromatic), 6.93−7.16 (m,
10H, aromatic), 8.46 (s, 1H, NH), 9.12 (s, 1H, OH), 9.58 (s, 1H,
OH). 13C NMR (75 MHz, DMSO-d6): δ 19.5, 46.6, 64.1, 65.8, 107.1,
111.1, 117.4, 132.0, 132.9, 132.9, 133.2, 134.2, 135.8, 137.1, 142.7,
145.9, 162.1, 163.5, 175.2, 175.3, 176.6.
Ethyl 2-[2-Phenyl-2-(3,4,5-trihydroxy-N-phenylbenzamido)-
acetamido]acetate (12). Recrystallization from petroleum ether and
1
ethyl acetate. Yield: 306 mg, 33%. Mp: 193−194 °C dec. H NMR
(300 MHz, DMSO-d6): δ 1.18 (t, 3H, CH3 of Et), 3.76−3.99 (m, 2H,
CH2 of Et), 4.06−4.13 (q, J = 6.9 Hz, 2H, CH2), 6.21 (s, 2H,
aromatic), 6.36 (s, 1H,CH), 6.95 (s, 5H), 7.15 (s, 5H, aromatic), 8.34
(s, 1H, OH), 8.56 (t, 1H, NH), 8.80 (s, 2H, OH). 13C NMR (75
MHz, DMSO-d6): δ 13.9, 41.0, 60.3, 63.9, 108.0, 126.1, 126.2, 127.5,
127.6, 130.2, 130.3, 134.3, 135.1, 140.9, 144.7, 169.6, 170.0, 170.1.
(E)-Ethyl 2-[2-(4-Hydroxy-3-methoxyphenyl)-2-(3-(4-hydroxy-3-
methoxyphenyl)-N-(4-hydroxyphenyl)acrylamido)acetamido]-
acetate (13). Purified by column chromatography with petroleum
ether and ethyl acetate as eluent. Yield: 462 mg, 42%. Mp: 150−154
Ethyl 2-[2-(4-Hydroxy-3-methoxyphenyl)-2-(N-phenyl-
benzamido)acetamido]acetate (7). Purified by column chromatog-
raphy with petroleum ether and ethyl acetate as eluent. Yield: 822 mg,
1
89%. Mp: 169−171 °C. H NMR (300 MHz, CDCl3): δ 1.27 (t, 3H,
CH3 of Et), 3.67 (s, 3H, OCH3), 4.11 (t, 2H, CH2 of Et), 4.16−4.23
(q, J = 7.2 Hz, 2H, CH2), 5.62 (s, 1H, CH), 6.26 (s, 1H, NH), 6.71−
7.18 (m, 12H, aromatic), 7.31 (d, J = 7.8, 1H, aromatic). 13C NMR
(75 MHz, DMSO-d6): δ 14.0, 41.1, 55.4, 60.4, 63.8, 114.7, 114.9,
123.5, 125.2, 126.6, 127.5, 127.6, 127.9, 128.9, 131.0, 136.9, 140.3,
146.1, 146.7, 169.7, 169.8, 170.4.
1
°C. H NMR (300 MHz, DMSO-d6): δ 1.17 (t, 3H, CH3 of Et), 3.56
(s, 3H, OCH3), 3.70 (s, 3H, OCH3), 3.77−4.00 (m, 2H, CH2 of Et),
4.05−4.11 (q, J = 6.9, 2H, CH2), 6.00 (d, J = 15.6, 1H, CHCH),
6.15 (s, 1H, CH), 6.55 (s, 6H, aromatic), 6.70−6.76 (m, 3H,
aromatic), 6.88 (s, 1H, aromatic), 7.39 (d, J = 15.6, 1H, CHCH),
8.37 (t, 1H, NH), 8.90 (s, 1H, OH), 9.44 (s, 1H, OH), 9.47 (s, 1H,
OH). 13C NMR (75 MHz, DMSO-d6): δ 14.1, 41.0, 55.4, 55.6, 60.4,
63.2, 112.3, 114.7, 114.8, 114.9, 115.9, 116.6, 120.4, 123.5, 125.8,
126.4, 130.5, 132.1, 141.0, 146.0, 146.7, 147.7, 148.5, 156.4, 165.7,
169.8, 170.7.
Ethyl 2-[2-(4-Hydroxy-3-methoxyphenyl)-2-(4-hydroxy-N-
phenylbenzamido)acetamido]acetate (8). Recrystallization from
C2H5OH/H2O. Yield: 640 mg, 67%. Mp: 134−136 °C. 1H NMR
(300 MHz, DMSO-d6): δ 1.18 (t, 3H, CH3 of Et), 3.53 (s, 3H,
OCH3), 3.74−4.04 (m, 2H, CH2 of Et), 4.05−4.12 (q, J = 7.2 Hz, 2H,
CH2), 6.27 (s, 1H, CH) 6.46−6.63 (m, 5H, aromatic), 6.98−7.07 (m,
7H, aromatic), 8.46 (t, 1H, NH), 8.90 (s, 1H, OH), 9.68 (s, 1H, OH).
13C NMR (75 MHz, DMSO-d6): δ 13.9, 40.9, 55.2, 60.2, 63.7, 114.0,
114.6, 114.7, 123.3, 125.4, 126.3, 126.9, 127.5, 130.3, 130.7, 140.9,
145.9, 146.6, 158.0, 169.4, 169.6, 170.5.
Ethyl 2-[2-(4-Hydroxy-3-methoxyphenyl)-2-(N-(4-hydroxy-
phenyl)benzamido)acetamido]acetate (9). Recrystallization from
C2H5OH/H2O. Yield: 602 mg, 63%. Mp: 203−205 °C dec. 1H
(E)-N-[2-(3-Benzoylphenylamino)-2-oxo-1-phenylethyl)-3-(4-hy-
droxy-3-methoxyphenyl)-N-phenylacrylamide (14). Purified by
column chromatography with petroleum ether and ethyl acetate as
1
eluent. Yield: 384 mg, 33%. Mp: 233−235 dec. H NMR (400 MHz,
G
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DMSO-d6): δ 3.68 (s, 3H, OCH3), 5.96 (d, J = 15.6, 1H, CHCH),
6.36 (s, 1H, CH), 6.69−6.75 (q, J = 10.4, 2H, aromatic), 6.86 (s, 1H,
aromatic), 7.11−7.27 (m, 9H, aromatic), 7.46 (d, J = 15.6, 1H, CH
CH), 7.54−7.84 (m, 11H, aromatic), 9.47 (s, 1H, NH), 10.72 (s, 1H,
OH). 13C NMR (100 MHz, DMSO-d6): δ 55.5, 64.8, 112.1, 115.8,
115.8, 118.3, 120.8, 126.1, 127.7, 128.1, 128.1, 128.4, 129.3, 130.3,
130.7, 131.1, 131.2,131.2, 131.4, 131.5, 132.2, 134.0, 137.5, 139.0,
141.8, 143.2, 147.6, 148.7, 165.6, 169.6, 194.5.
120.3, 123.3, 126.1, 126.3, 130.7, 132.1, 140.8, 146.0, 146.7, 147.6,
148.4, 156.3, 165.6, 169.9.
Scavenging Radicals. The tests for scavenging ABTS•+, DPPH,
and galvinoxyl radical were performed by following a previous
description.26 ABTS salt and K2S2O8 were dissolved in 2.0 mL of
water, in which the final concentrations of ABTS salt and K2S2O8 were
4.0 and 1.41 mM, respectively. The aforementioned solution was kept
for 16 h and then diluted with 100 mL of ethanol to give an ABTS•+
•+
solution, whose absorbance was around 0.80 at 734 nm (εABTS = 1.6
N-(2-(tert-Butylamino)-1-(4-hydroxy-3-methoxyphenyl)-2-ox-
oethyl)-4-hydroxy-N-(4-hydroxyphenyl)benzamide (15). Purified by
column chromatography with petroleum ether and ethyl acetate as
× 104 M−1 cm−1). DPPH and galvinoxyl radical were dissolved in 50
mL of ethanol, and the absorbances were around 1.00 at 517 nm
(εDPPH = 4.09 × 103 M−1 cm−1) and 428 nm (εgalvinoxy = 1.4 × 105 M−1
cm−1), respectively. Dimethyl sulfoxide (DMSO) solutions of bis-
amides (0.1 mL) were added to 1.9 mL of ABTS•+ solution, with the
final concentrations being 300.0 μM for compounds 1−5, 25.0 μM for
6, 10.0 μM for 7−10 and 15, 5.0 μM for 11, 13, 14, 17, 19, and 20,
and 2.5 μM for 12, 16, and 18. The DMSO solutions (0.1 mL) of bis-
amides were added to 1.9 mL of DPPH solution, with the final
concentrations being 100.0 μM for compounds 13 and 20, 10.0 μM
for 12, 16, and 18, and 300.0 μM for the other compounds. The
DMSO solutions of bis-amides (0.1 mL) were added to 1.9 mL of
galvinoxyl radical solution, with the final concentrations being 100.0
μM for compounds 13 and 20, 5.0 μM for 18, 2.5 μM for 12 and 16,
and 300.0 μM for the other compounds. The decrease in the
absorbance of these radicals was recorded at 25 °C within a certain
time interval.
1
eluent. Yield: 584 mg, 63%. Mp: 259−261 °C dec. H NMR (300
MHz, DMSO-d6): δ 1.25 (s, 9H, C(CH3)3), 3.54 (s, 3H, OCH3), 6.01
(s, 1H, CH), 6.32 (d, J = 7.5, 2H, aromatic), 6.48−6.53 (m, 6H,
aromatic), 6.78 (s, 1H, aromatic), 7.03 (d, J = 8.7, 2H, aromatic), 7.57
(s, 1H, OH), 8.86 (s, 1H, NH) 9.20 (s, 1H, OH), 9.63 (s, 1H, OH).
13C NMR (75 MHz, DMSO-d6): δ 28.5, 50.2, 55.4, 64.4, 114.0, 114.1,
114.4, 114.7, 123.1, 126.7, 127.6, 130.3, 132.0, 132.4, 145.7, 146.7,
155.3, 157.9, 169.4, 169.8.
N-(2-(tert-Butylamino)-2-oxo-1-phenylethyl)-3,4,5-trihydroxy-N-
phenylbenzamide (16). Recrystallization from petroleum ether and
1
ethyl acetate. Yield: 312 mg, 36%. Mp: 238−239 °C. H NMR (300
MHz, DMSO-d6): δ 1.24 (s, 9H, C(CH3)3), 6.21 (s, 3H, CH and
aromatic), 6.93−7.13 (m, 10H, aromatic), 7.74 (s, 1H, OH), 8.31 (s,
1H, OH), 8.56 (t, 1H, NH), 8.78 (s, 2H, OH). 13C NMR (75 MHz,
DMSO-d6): δ 28.4, 50.3, 64.7, 108.1, 126.1, 126.7, 127.3, 127.5, 127.7,
129.8, 130.4, 134.3, 136.2, 141.2, 144.8, 168.9, 169.9.
Inhibiting AAPH-Induced Oxidation of DNA. AAPH-induced
oxidation of DNA was performed following a previous description.36
DNA sodium salt and AAPH were dissolved in phosphate-buffered
solution (PBS: 8.1 mM Na2HPO4, 1.9 mM NaH2PO4, 10.0 mM
EDTA), with the final concentrations being 2.24 mg/mL and 40 mM,
respectively. The aforementioned solution also contained various
concentrations of bis-amides (dissolved in 0.1 mL of DMSO) except in
the blank experiment, which also contained the same volume of
DMSO as the control. The solution was then dispatched into test
tubes, with each one containing 2.0 mL. These tubes were heated to
37 °C in a water bath to initiate the oxidation of DNA. Three of them
were taken out at every 2 h and cooled to room temperature, followed
by adding 1.0 mL of thiobarbituric acid (TBA) solution (1.00 g of
TBA and 0.40 g of NaOH dissolved in 100 mL of PBS) and 1.0 mL of
3.0% trichloroacetic acid aqueous solution and then heating in a
boiling water bath for 15 min. After the tubes were cooled to room
temperature immediately, 1.5 mL of n-butanol was added and the
mixture shaken vigorously to extract thiobarbituric acid reactive species
(TBARS). Finally, the tubes were centrifuged for few minutes to
obtain an n-butanol layer for measuring the absorbance at 535 nm
(εTBARS = 1.56 × 105 M−1 cm−1).37
(E)-N-(2-(tert-Butylamino)-2-oxo-1-phenylethyl)-3-(4-hydroxy-3-
methoxyphenyl)-N-phenylacrylamide (17). Purified by column
chromatography with petroleum ether and ethyl acetate as eluent.
Yield: 467 mg, 51%. Mp: 224−225 °C. 1H NMR (300 MHz, DMSO-
d6): δ 1.25 (s, 9H, C(CH3)3), 3.68 (s, 3H, OCH3), 5.93 (d, J = 14.7,
1H, CHCH), 6.18 (s, 1H, CH), 6.72 (s, 2H, aromatic), 6.87 (s, 1H,
aromatic), 7.01−7.17 (m, 10H, aromatic), 7.43 (d, J = 15.6, 1H, CH
CH), 7.78 (t, 1H, NH), 9.44 (s, 1H, OH). 13C NMR (75 MHz,
DMSO-d6): δ 28.5, 50.3, 55.5, 63.9, 112.0, 115.8, 116.3, 120.6, 126.2,
127.4, 127.4, 127.8, 128.2, 130.0, 131.1, 135.9, 139.6, 141.3, 147.6,
148.5, 165.3, 169.2.
N-(2-Ferrocenylmethylamino)-2-oxo-1-phenylethyl)-3,4,5-trihy-
droxy-N-phenylbenzamide (18). Recrystallization from C2H5OH/
1
H2O. Yield: 645 mg, 56%. Mp: 155−158 °C. H NMR (400 MHz,
DMSO-d6): δ 3.98−4.16 (m, 11H, ferrocenyl and CH2), 5.75 (s, 1H,
CH), 6.22 (s, 2H, aromatic), 6.98 (s, 5H, aromatic), 7.15 (s, 5H,
aromatic), 8.17 (s, 1H, OH), 8.31 (s, 1H, NH), 8.78 (s, 2H, OH). 13C
NMR (100 MHz, DMSO-d6): δ 37.8, 64.7, 67.1, 67.2, 67.5, 67.6, 68.3,
86.1, 108.1, 126.3, 126.5, 127.6, 127.8, 130.1, 130.4, 134.4, 135.6,
141.2, 144.8, 169.3, 170.0.
Statistical Analysis. All data were average values from at least
three independent measurements, with the experimental error being
within 10%. The equations in the present work were fitted by using
Origin 7.5 professional software, and p < 0.001 indicated a significant
difference.
(E)-N-(2-(Ferrocenylmethylamino)-2-oxo-1-phenylethyl)-3-(4-hy-
droxy-3-methoxyphenyl)-N-phenylacrylamide (19). Recrystallization
1
from C2H5OH/H2O. Yield: 960 mg, 80%. Mp: 183−184 °C dec. H
NMR (400 MHz, DMSO-d6): δ 3.68 (s, 3H, OCH3), 3.98−4.16 (m,
11H, ferrocenyl and CH2), 5.94 (d, J = 15.2, 1H, CHCH), 6.24 (s,
1H, CH), 6.69−6.74 (q, J = 4.0, 2H, aromatic), 6.86 (s, 1H, aromatic),
7.13 (s, 6H, aromatic), 7.20 (s, 4H, aromatic), 7.44 (d, J = 15.6, 1H,
CHCH), 8.26 (s, 1H, NH), 9.44 (s, 1H, OH). 13C NMR (100
MHz, DMSO-d6): δ 37.8, 55.5, 63.9, 67.1, 67.2, 67.6, 67.7, 68.3, 86.0,
112.0, 115.8, 116.2, 120.6, 126.2, 127.5, 127.7, 127.8, 128.3, 130.2,
131.0, 135.3, 139.5, 141.4, 147.6, 148.5, 165.4, 169.3.
ASSOCIATED CONTENT
* Supporting Information
■
S
Figures and tables giving 1H and 13C NMR spectra for
compounds 1−20, the decay of the radical concentrations, the
increase of the absorbance of TBARS in AAPH-induced
oxidation of DNA, and equations of [radical] vs reaction
period and its differential style together with the reaction rate at
t = 0 (r0). This material is available free of charge via the
Internet at http://pubs.acs.org.
(E)-N-(2-(Ferrocenylmethylamino)-1-(4-hydroxy-3-methoxyphen-
yl)-2-oxoethyl)-3-(4-hydroxy-3-methoxyphenyl)-N-(4-
hydroxyphenyl)acrylamide (20). Recrystallization from C2H5OH/
H2O. Yield: 741 mg, 56%. Mp: 170−172 °C dec. 1H NMR (400 MHz,
DMSO-d6): δ 3.51 (s, 3H, OCH3), 3.70 (s, 3H, OCH3), 3.88−4.06
(m, 11H, ferrocenyl and CH2), 5.99 (s, 1H, CH), 6.04 (s, 2H, aromatic
and CHCH), 6.51 (s, 2H, aromatic), 6.55 (s, 3H, aromatic), 6.70−
6.76 (m, 3H, aromatic), 6.89 (s, 1H, aromatic), 7.39 (d, J = 15.6, 1H,
CHCH), 8.1 (s, 1H, NH), 8.89 (s, 1H, OH), 9.42 (s, 1H, OH), 9.47
(s, 1H, OH). 13C NMR (100 MHz, DMSO-d6): δ 37.6, 55.3, 55.7,
63.5, 67.1, 67.1, 67.5, 67.6, 68.3, 86.3, 112.2, 114.5, 114.8, 115.9, 116.6,
AUTHOR INFORMATION
Corresponding Author
*E-mail for Z.-Q.L.: zaiqun-liu@jlu.edu.cn.
■
Notes
The authors declare no competing financial interest.
H
dx.doi.org/10.1021/jo401426n | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
(32) Bowry, V. W.; Stocker, R. J. Am. Chem. Soc. 1993, 115, 6029−
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(33) Li, Y.-F.; Liu, Z.-Q.; Luo, X.-Y. J. Agric. Food Chem. 2010, 58,
ACKNOWLEDGMENTS
■
Financial support from Jilin Provincial Science and Technology
Department, People’s Republic of China, is acknowledged
gratefully (20130206075GX).
4126−4131.
(34) Obrecht, R.; Herrmann, R.; Ugi, I. Synthesis 1985, 4, 400−402.
(35) Niu, T.-F.; Lu, G.-P.; Cai, C. J. Chem. Res. 2011, 35, 444−447.
(36) Zhao, C.; Liu, Z.-Q. Biochimie 2013, 95, 842−849.
(37) Reed, C. J.; Douglas, K. T. Biochem. J. 1991, 275, 601−608.
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