Synthesis and structural study of benzamarones by X-ray and NMR spectroscopy

Article abstract of DOI:10.1016/j.molstruc.2010.12.005

In this work only one diastereomer of benzamarone (1,2,3,4,5- pentaphenylpentan-1,5-dione) 1 was isolated from tandem condensation/addition reaction between deoxybenzoin and benzaldehyde in alkaline medium and by Michael addition of deoxybenzoin to (E)-2-

Full text of DOI:10.1016/j.molstruc.2010.12.005

Journal of Molecular Structure 987 (2011) 119–125
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
Synthesis and structural study of benzamarones by X-ray and NMR spectroscopy
a
c
Jorge D. Mufato a, Daniel R. Vega b, José M. Aguirre a, , Diego J. de la Faba , Beatriz Lantaño
⇑
a Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján 6700, Argentina
b Unidad Actividad Física, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Argentina
c Departamento de Química Orgánica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 October 2010
Received in revised form 30 November 2010
Accepted 2 December 2010
Available online 14 December 2010
In this work only one diastereomer of benzamarone (1,2,3,4,5-pentaphenylpentan-1,5-dione) 1 was iso-
lated from tandem condensation/addition reaction between deoxybenzoin and benzaldehyde in alkaline
medium and by Michael addition of deoxybenzoin to (E)-2-phenylchalcone. Compound 1 was investi-
gated by single crystal X-ray diffraction: C35H28O2, Mr = 480.57, triclinic system, space group P1 with unit
cell parameters a = 11.489(2), b = 11.669(2), c = 11.855(2) Å,
a = 104.31(4), b = 116.91(3), c = 98.96(3)°,
V = 1305.6(4) Å3, Z = 2, T = 25(2) °C, calc = 1.222 gr/cm3, = 0.074 mmꢀ1. This study allowed us to assign
q
l
Keywords:
X-ray crystallography
NMR
the configuration 2R,4R/2S,4S corresponding to the diastereomer racemate C (Fig. 1) due to the fact that
the crystal structure exhibits two independent molecules in the unit cell. Data obtained using NMR spec-
troscopy [1D and 2D NMR] are agreement with those obtained by X-ray diffraction. By comparison of
NMR data, the configuration corresponding to the diastereomer racemate C was assigned to other substi-
tuted benzamarones synthesized by us, which present two and three stereocenters in their structure.
Ó 2010 Elsevier B.V. All rights reserved.
Benzamarone
Configurational assignment
Tandem condensation/addition reaction
Michael addition
1. Introduction
have identical chemical shifts NMR spectra unless there is a slow
rotation in an NMR time scale that could display conformational
Benzamarone (1,2,3,4,5-pentaphenylpentan-1,5-dione) 1 was
early reported by Knoevenagel and Weissgerber [1]. Later, Bowie
[2] conducted a mass spectroscopy study of 1 and suggested a frag-
mentation scheme. This diketone has been used as a polyaryl sub-
strate in the synthesis of heterocyclic compounds [3,4] and several
derivative products of 1 have been described in attempts to
synthesize thrombin inhibitors [5]. We obtained 1 attempting to
develop stereodirected synthesis of substituted indanes and tetra-
lins. Paranjpe and Bagavant [6] synthesized several benzamarones
containing different aryl groups in C-3 but indicated only the melt-
ing point and elemental analysis for these compounds. All these
works [2–6] have reported that only one stereoisomer of benza-
marones has been isolated from tandem condensation/addition
reaction between deoxybenzoin and arylaldehydes in alkaline
medium. The configuration of these diketones has not been re-
ported yet and neither the crystal structure nor NMR data have
been previously published. Since these kinds of compounds can ap-
pear as four steroisomers: two meso forms (A and B) and one pair
of enantiomers (C) [7] (Fig. 1), the configurational assignment of
compound 1 is an interesting challenge.
asymmetry. On the other hand, in the two enantiomers (C), the car-
bon atoms C-2, C-3, C-4 and their attached hydrogen atoms have a
different environment and therefore show different NMR chemical
shifts, irrespective whether there is rapid rotation around single
bonds. The above considerations suggest that NMR spectroscopy
could not be used in the unambiguous differentiation between a
configurational asymmetry corresponding to racemate C and a
conformational asymmetry that the meso forms A and B could dis-
play. This paper reports our research and results that led to the
unequivocal configurational assignment of compound 1, using X-
ray diffraction analysis. In addition, we present the results of the
application of NMR spectroscopy [1H and 13C, NOESY (Nuclear
Overhauser Effect Spectroscopy), heteronuclear 1H–13C HMQC
(1H–13C heteronuclear multiple quantum correlation) and 1H–13
C
HMBC (1H–13C heteronuclear multiple bond correlation)] to this
structural problem and compare them with those obtained by
X-ray diffraction. Finally, we report the configurational assignment
of other substituted benzamarones synthesized by comparing NMR
data.
Both meso forms (A and B) have planes of symmetry if rotation
around all the single bonds is fast. In these isomers, C-2 and C-4
and their attached hydrogen atoms result enantiotopic and will
2. Results and discussion
2.1. Synthesis of benzamarone 1
⇑
Compound 1 was isolated as a sole product by applying tandem
condensation/addition (pathway a) [6] and Michael addition
Corresponding author.
E-mail address: jaguirre@unlu.edu.ar (J.M. Aguirre).
0022-2860/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2010.12.005

120
J.D. Mufato et al. / Journal of Molecular Structure 987 (2011) 119–125
O
Ph
Ph
O
H
Ph
Ph
Ph
O
O
Ph
Ph
Ph
Ph
H
H
H
Ph
H
H
H
Ph
Ph
Ph
H
H
Ph
H
Ph
H
Ph
H
O
Ph
Ph
O
Ph
O
)
O
Ph
(R,R)
(S,S
(
R
,
s,
S
)
(
R
,r
,
S
)
A
B
C
Fig. 1. Steroisomers of benzamarone.
(pathway b) (Scheme 1). The compound obtained was a white solid
(m.p. 219–221 °C) [6], its m/z was 480 and its fragmentation
agreed with the pattern described by Bowie [2].
2.2. X-ray crystal structure of compound 1
The crystals of 1 obtained by slow evaporation of a methanol
solution at room temperature belong to the triclinic system, space
group P1 with unit cell parameters a = 11.489(2), b = 11.669(2),
c = 11.855(2) Å,
a
= 104.31(4), b = 116.91(3),
c
= 98.96(3)°, V =
1305.6(4) Å3, Z = 2, T = 25(2) °C,
q
calc = 1.222 gr/cm3,
l
= 0.074 mmꢀ1
.
Although no crystallographic symmetry elements are present, the
crystal structure exhibits two independent molecules in the unit
cell (called C-I and C-II): the expected enantiomorphic pair that
confirms a racemate compound 2R,4R/2S,4S. Figs. 2 and 3 give a
perspective view of molecules C-I (2R,4R) and C-II (2S,4S) respec-
tively, with the numbering scheme. Molecules C-I and C-II can be
compared analyzing the torsional angles around the C1AC2,
C2AC3, C3AC4 and C4AC5 bonds. The values observed for
molecule C-I are: C11AC1AC2AC3 –151.5(8), C1AC2AC3AC4 –
174.3(7), C2AC3AC4AC5 82.6(9) and C3AC4AC5AC51 –142.7(8)°,
whereas those for molecule C-II are: 153.9(7), 174.1(7), ꢀ77.9(9)
and 155.2(8)°. These values show that clockwise torsional angles
in molecule C-I are anticlockwise in molecule C-II and vice versa,
as expected for an enantiomorphic pair of molecules. However,
molecule C-II is different from the centrosymmetric image of mol-
ecule C-I. This conformational difference could thus be the reason
for obtaining an enantiomorphic pair with no symmetry elements
relating them. The fact that two enantiomorphic molecules crystal-
lize in a racemic compound with no symmetry elements relating
them is not new, but is always exciting [8]. When analyzing the
absolute values of these torsional angles, a difference as large as
12° can be observed for the torsional angle around the C4AC5
bond, stating the magnitude of the difference. In addition, it is
worth mentioning that each of the group defined by terminal phe-
nyl and carbonyl in the two molecules is essentially planar, and the
maximum deviation from each of the four phenyl-carbonyl mean
planes for O1A is 0.1 Å.
Fig. 2. A view of the molecule C-I (2R,4R) of compound 1, showing the atomnum-
bering scheme and displacement ellipsoids at a 30% probability level.
(J = 7.6 and 10.5 Hz) and two doublets at d = 5.07 ppm (J = 7.6 Hz)
and d = 5.24 ppm (J = 10.5 Hz). Among the signals of aromatic
hydrogens there are three well defined doublets integrating for
two hydrogen atoms at d = 7.43 ppm (J = 7.7 Hz), d = 7.61 ppm
(J = 7.8 Hz) and d = 7.72 ppm (J = 7.8 Hz) respectively. The 13C
NMR spectrum shows three sp3 carbon atoms at d = 50.8, 56.0
and 58.7 ppm and two carbonyl carbons at d = 198.3 and
198.5 ppm. The 1H NMR spectrum of compound 1 showed no sig-
nificant differences when it was carried out in different solvents
(CDCl3, benzene-d6 and DMSO-d6) and even when the temperature
was modified (25 °C and 65 °C). Table 1 summarizes the data from
HMQC and HMBC correlation spectra of compound 1. The signals at
5.07, 4.88 and 5.24 ppm corresponding to H-2, H-3 and H-4. HMQC
experiment allows for the assignment the chemical shifts of C-2, C-
3 and C-4 (56.0, 50.6 and 58.7 ppm respectively). The HMBC exper-
iments show all the connectivities which are needed to assign the
chemical shifts of hydrogen and carbon atoms in ortho positions of
phenyl groups and carbonyl groups. The chemical shifts of hydro-
gen and carbon used in structural analysis of 1 are shown in Fig. 4.
The NOESY experiment performed on compound 1 presents rel-
evant data about its structure (Fig. 5a). The H-2 at d = 5.07 ppm
showed NOE with H-4 at d = 5.24 ppm and with Hortho at
d = 7.43 ppm corresponding to the aryl group bound to C-4,
whereas the H-4 at d = 5.24 ppm did not show NOE with the Hortho
2.3. NMR spectroscopy analysis of compound 1
The 1H NMR spectrum of 1 shows the following signals for the
three aliphatic hydrogen atoms: a double doublet at d = 4.88 ppm
O
O
O
O
O
a
b
Ph
Ph
Ph
Ph
Ph
PhCHO
+
+
Ph
Ph
a. NaMeO/MeOH 25%; 20 h; rt
b. NaMeO/MeOH 25%; 72 h; rt
1
Scheme 1.

J.D. Mufato et al. / Journal of Molecular Structure 987 (2011) 119–125
121
2.4. Configurational assignment of substituted benzamarones
In order to analyze the stereochemistry of benzamarones with
two and three stereocenters, we synthesized compounds 2–5 using
the pathways described in Scheme 2. High yields were obtained for
compounds 2–4 and in the three cases only one compound was
isolated (Table 2). Their NMR spectra showed the same chemical
shift pattern of aliphatic hydrogen and carbon atoms as those cor-
responding to 1 (Table 3). Therefore, these data allowed us to as-
sign benzamarones 2–4
compound 1 (2R,4R/2S,4S).
a configuration identical to that of
Benzamarones with three stereocenters were synthesized using
a Michael addition of 2-(4-methoxyphenyl)-1-phenyletanone (6)
to (E)-1,2,3-triphenylpropenone (7) (Scheme 2). Two stereoiso-
mers, 5a and 5b, were isolated from the reaction mixture. NMR
spectra data of these compounds are summarized in Tables 4 and
5. The signals at d = 4.98, 4.80 and 5.21 ppm of compound 5a cor-
responding to H-2, H-3 and H-4, and HMQC experiment allow for
the assignment of the chemical shifts of C-2, C-3 and C-4 (55.5,
51.4 and 59.1 ppm respectively). Long-range connectivities are
accessible from the 1H–13C-HMBC spectra. The HMBC experiments
show all the connectivities which are needed to assign the chemi-
cal shifts of hydrogen and carbon atoms to ortho positions of anisyl
and phenyl groups. In a similar manner we assigned the chemical
shifts of 5b. Thus, in compound 5a the anisyl group is bonded to
the carbon atom at d = 55.5 ppm, meanwhile in 5b this group is
bonded to the carbon atom at d = 59.2 ppm (Fig. 6).
Fig. 3. A view of the molecule C-II (2S,4S) of compound 1, showing the atomnum-
The chemical shifts of the aliphatic carbons of the diastereo-
mers 5a and 5b showed values similar to those of compounds 1
to 4 (Table 4). The chemical shifts of H-2 and H-4 in 5a and 5b were
also similar to those of compound 1 if we consider the effect
caused by substituting a phenyl group by an anisyl group, which,
in this type of structure, is almost 0.1 ppm (H-2 and H-4 of com-
pound 4 in relation to H-2 and H-4 of compound 1, see Table 3).
The NOE experiments for compounds 5a and 5b showed effects
identical to those observed in compound 1. All these data of
NMR spectroscopy allowed us to assign, by comparison, the config-
uration 2S,3S,4S/2R,3R,4R to 5a and 2S,3R,4S/2R,3S,4R to 5b (Fig. 7).
bering scheme and displacement ellipsoids at a 30% probability level.
Table 1
HMQC and HMBC data of compound 1.
Y
dH (ppm) HMQC 1J HMBC 2J
HMBC 3J
H-2
H-3
H-4
5.07 d
4.88 dd
5.24 d
56.0
50.8
58.8
50.8, 198.3
56.0, 58.8, 140.3 129.9, 198.3, 198.5
50.8, 198.5
58.8, 130.2, 140.3
56.0, 130.3, 140.3
H
H
H
H
H
ortho(Ar-1) 7.61 d
ortho(Ar-2) 7.03 d
ortho(Ar-3) 7.10 d
ortho(Ar-4) 7.43 d
ortho(Ar-5) 7.72 d
128.7
130.2
129.9
130.3
128.6
198.3
56.0
50.8
58.8
198.5
3. Conclusions
of the aryl group bound to C-2 (d = 7.03 ppm). In addition, H-2 and
H-4 have NOE with the ortho hydrogen atoms of the phenyl groups
linked to C-1 and C-5 (d = 7.61 ppm and d = 7.72 ppm, respectively)
and NOE with the Hortho of the aryl group bound to C-3
(d = 7.10 ppm). Fig. 5b shows a space distribution for 1 that arises
from the analysis of the NOESY data. The information above is
clearly in accordance with the configuration assigned by X-ray
data.
By means of studies of X-ray crystallography, we were able to as-
sign the configuration 2R,4R/2S,4S, corresponding to the diastereo-
mer racemate C, to Benzamarone (1) (Fig. 1), because, it exhibits
two independent molecules in the unit cell of the crystal structure:
the expected enantiomorphic pair. Data of 1 obtained using NMR
spectroscopy are in agreement with those obtained by X-ray diffrac-
tion. In addition, by comparison of NMR data we were able to assign
the configuration of other synthetic substituted benzamarones
3
129.9
7.10
H
140.3
7.61
7.72
H
H
O
O
5.07
5.24
H
5.07
O
O
5.24
H50.8
H
128.6
H
128.7
198.5
198.3
56.0
H
58.8
7.43
H
1
5
4.88
4.88
7.03
H
H
130.2
130.3
2
4
Fig. 4. 1H NMR and 13C NMR selected chemical shifts of compound 1.

122
J.D. Mufato et al. / Journal of Molecular Structure 987 (2011) 119–125
7.10
H
H
7.72
7.61
H
H
5.24
H
O
O
5.07
5.07
5.24
H
H
H
O
H
4.88
R
R
H
H
H
7.43
7.03
O
A
B
Fig. 5. Data from NOE experiments (a) and space distribution (b) of compound 1 (enantiomer 2R,4R).
H; OCH3
O
O
O
O
O
a
b
Ph
Ph
Ph
Ar4
Ar2
Ar3CHO
+
+
Ph
Ph
H; OCH3
H3CO; H
b. NaMeO/MeOH 25%; 72 h; rt
Ar4: Phenyl; 4-Methoxyphenyl
2-5b
a. NaMeO/MeOH 25%; 20 h; rt
Ar2: Phenyl; 4-Methoxyphenyl
Ar3: Phenyl; 4-Methoxyphenyl; 3,4-Dimethoxyphenyl
Scheme 2.
4. Experimental
Table 2
Synthesized 1,2,3,4,5-pentaarylpentan-1,5-diones.
4.1. General
Ph-CO-CH(Ar-2)-CH(Ar-3)-CH(Ar-4)-CO-Ph
Ar-2
Ar-3
Ar-4
Pathway
mp °C
Yield%
The nuclear magnetic resonance (NMR) spectra were recorded
(CDCl3) on a Bruker AC-300 or Bruker AC-500 spectrometers. Shifts
reported are relative to internal standard Me4Si and coupling con-
stants are reported in Hz (s: singlet, bs: broad singlet, d: doublet, t:
triplet, q: quartet, dd: double doublet, dt: double triplet, m: multi-
plet). Mass spectra were recorded on a VG AutoSpec or Shimadzu
QP 5000-GC 17A and are reported as percent relative intensity to
the base peak. Preparative thin layer chromatography (p-TLC)
was done on Merck Silica Gel 60 GF254 and analytical TLC was per-
formed on Merck aluminum sheets Silica Gel 60 F254. The chro-
matographic column was performed on Silicagel 60, 230–400
mesh ASTM. Melting points are uncorrected and were determined
in a Büchi 510 apparatus. Solvents were distilled before their use
[9]. The deoxybenzoin and arylaldehydes were commercial.
1*
2*
3*
4
5a
5b
Ph
Ph
Ph
An
An
Ph
Ph
An
Ver
Ph
Ph
Ph
Ph
Ph
Ph
An
Ph
An
a/b
a
a
a
b
219–221
232–233
188–190
207–209
211–213
206–208
81/ 86
88
80
72
35
b
30
Ph: C6H5; An: 4-CH3OC6H4; Ver: 3,4-(CH3O)2C6H3
*
Ref. [6].
which present two and three stereocenters. In all cases, the
stereochemistry of the compounds obtained corresponded to
isomer C.
Table 3
1H and 13C NMR selected chemical shifts d (ppm), J (Hz).
Ph-CO-CH(Ar-2)-CH(Ar-3)-CH(Ar-4)-CO-Ph
H-2
H-3
H-4
C-1
C-2
C-3
C-4
C-5
1
2
3
4
5a
5b
5.07 d J: 7.6
5.01 d J: 7.0
4.99 d J: 6.5
4.97 d J: 7.6
4.98 d J: 6.9
5.13 d J: 10.5
4.88 dd
4.79 dd
4.80 dd
4.83 dd
4.80 dd
4.91 dd
5.24 d J: 10.5
5.18 d J: 10.5
5.23 d J: 10.9
5.11 d J: 10.5
5.21 d J: 10.5
5.03 d J: 8.1
198.3
198.6
198.6
198.5
199.2
199.2
56.0
54.9
55.4
54.9
55.5
59.2
50.8
50.0
50.3
50.7
51.4
51.6
58.8
58.5
57.8
58.4
59.1
56.9
198.5
198.7
198.7
198.6
199.3
198.9

J.D. Mufato et al. / Journal of Molecular Structure 987 (2011) 119–125
123
4.2. Synthesis of 1,2,3,4,5-pentaarylpentane-1,5-diones
(5 mL) and NaMeO/MeOH 25% (0.5 mL). After stirring for 20 h at
room temperature the reaction mixture was filtered, and then
washed with ethanol and water.
4.2.1. General procedure A: Tandem condensation/addition
A mixture of deoxybenzoins (5.1 mmol) and arylaldehydes
(5.1 mmol) was added to a well stirred solution of absolute ethanol
4.2.2. General procedure B: Michael addition
A mixture of (E)-1,2,3-triphenylpropen-1-one (0.7 mmol) and
deoxybenzoins (0.7 mmol) was added to a well stirred solution of
absolute ethanol (1 mL) and NaMeO/MeOH, 25% (0.1 mL). After
stirring for 72 h at room temperature the reaction mixture was fil-
tered and then washed with ethanol and water.
Table 4
HMQC and HMBC data of compound 5a.
Y
dH (ppm)
HMQC 1J
HMBC 2J
HMBC 3J
H-2
H-3
H-4
CH3O
4.98 d
4.80 dd
5.21 d
3.65 s
7.58 d
6.90 d
6.58 d
7.10 d
7.42 d
7.61 d
55.5
51.4
59.1
51.4, 199.2
55.5, 59.1, 141.0
51.4, 199.3
59.1, 130.2, 141.0
199.2, 199.3
55.5, 131.0, 141.0
4.2.2.1. 1,2,3,4,5-Pentaphenylpentane-1,5-dione 1. General proce-
dure A was carried out with a mixture of deoxybenzoin (1.0 g,
5.1 mmol), benzaldehyde (0.54 g, 5.1 mmol) in absolute alcohol
(5 mL) and NaMeO/MeOH 25% (0.5 mL) afforded 1 as white solid
(1.05 g, 86%), mp: 219–221 °C (EtOH). General procedure B was car-
ried out with (E)-1,2,3-triphenylpropen-1-one (0.10 g, 0.35 mmol)
and deoxybenzoin (0.07 g, 0.35 mmol) in solution of absolute eth-
anol (1 mL) and NaMeO/MeOH 25% (0.1 mL) afforded 1 as white
solid (0.137 g, 81%), mp: 219–221 °C (EtOH); (Lit. [6] 219 °C; Lit.
[3] 215 °C, Lit. [5] 214–216 °C). 1H NMR (CDCl3, 500 MHz): d 4.88
(dd, J = 7.6 and 10.5 Hz, 1H, H-3), 5.07 (d, J2,3 = 7.6 Hz, 1H, H-2),
5.24 (d, J3,4 = 10.5 Hz, 1H, H-4), 6.90–7.40 (m, 19H, H–Ar), 7.43
(d, J = 7.7 Hz, 2H), 7.61 (d, J = 7.8 Hz, 2H), 7.72 (d, J = 7.8 Hz, 2H)
ppm. 13C NMR (CDCl3, 75 MHz: d 50.8 (C-3), 56.0 (C-2), 58.8
(C-4), 126.0, 126.7, 127.4, 127.7, 128.0, 128.2, 128.26, 128.3,
128.6, 128.7, 129.9, 130.2, 130.3, 132.4, 132.5, 136.3, 136.5,
136.8, 137.2, 140.3, 198.3 (C-1 C@O), 198.5 (C-5 C@O) ppm. MS:
m/z (%) 480 (M+, 1), 375 (6), 300 (30), 285 (7), 196 (14), 180 (23),
179 (13), 178 (11), 167 (15), 165(14), 152 (7), 106 (14),
105 (100), 91 (3), 78 (4), 77 (36). Chiral HPLC analysis of 1 ren-
dered two peaks: 18.8 and 19.7 min [column, CHIRALCEL OD,
55.7
H
H
H
H
H
H
ortho(Ar-1)
129.1
132.0
114.1
199.2
55.5
ortho(Ar-2)
meta(Ar-2)
ortho(Ar-3)
ortho(Ar-4)
ortho(Ar-5)
114.1
132.0
51.4
59.1
199.3
131.0
128.7
Table 5
HMQC and HMBC data of compound 5b.
Y
dH (ppm)
HMQC 1J
HMBC 2J
HMBC 3J
H-2
H-3
H-4
CH3O
5.13 d
4.91 dd
5.03 d
3.63 s
7.68 d
7.30 d
6.58 d
7.10 d
7.03 d
7.62 d
59.2
51.6
56.9
51.6, 199.2
56.9, 59.2, 141.4
51.6, 198.9
56.9, 132.3, 141.4
199.2, 198.9
59.2, 130.9, 141.4
55.7
H
H
H
H
H
H
ortho(Ar-1)
129.0
132.3
114.8
199.2
59.2
ortho(Ar-2)
meta(Ar-2)
ortho(Ar-3)
ortho(Ar-4)
ortho(Ar-5)
114.8
132.3
51.6
56.9
198.9
130.9
128.9
H
7.10
7.10
H
141.4
141.0
7.68
7.58
7.62
H
H
7.61
H
H
5.13
4.98
O
199.2
5.03
H
O
5.21
H
O
199.2
O
H
129.0
198.9
H
129.1
199.3
128.7
128.9
51.6
51.4
59.2
H
56.9
55.5
H
59.1
4.91
4.80
7.30
7.03
6.90
7.42
H
H
130.9
H
H
131.0
132.3
132.0
6.58
6.58
H
H
114.8
114.1
O
O
3.63
55.7
3.65
55.7
5a
5b
Fig. 6. 1H NMR and 13C NMR selected chemical shifts of compounds 5a and 5b.
O
Ph
Ph
O
H
Ph
Ph
O
H
Ph
An
Ph
Ph
O
Ph
O
Ph
O
Ph
H
H
H
Ph
An
An
H
H
Ph
H
H
H
Ph
Ph
An
H
H
Ph
H
H
H
Ph
Ph
H
Ph
Ph
Ph
H
H
O
Ph
Ph
O
O
Ph
Ph
O
Ph
O
Ph
O
S
(2
S
,3
S
,4
S
)
(2
R
,3
R
,4
R
)
(2
S
,3
R
,4
S
)
R S R
(2 ,3 ,4 )
(2
S
,4
R R
,4 )
1
5a
5b
Fig. 7. Structures of compounds 1, 5a and 5b.

124
J.D. Mufato et al. / Journal of Molecular Structure 987 (2011) 119–125
(250 ꢁ 4.6 mm); eluent, n-hexane/i-PrOH = 90:10; detection by UV
at 254 nm; flow rate, 0.30 mL/min, 25 °C].
Crystal data. Data were acquired on a Rigaku AFC6S diffractom-
eter. All intensity measurements were performed using graphite
of 2-(4-methoxyphenyl)-1-phenylethanone (6) (0.17 g, 0.70 mmol)
and (E)-1,2,3-triphenylpropen-1-one (7) (0.20 g, 0.70 mmol) in
solution of absolute ethanol (1 mL) and NaMeO/MeOH 25%
(0.1 mL) afforded a mixture of 5a and 5b. These compounds were
isolated by p-TLC (Silicagel 60 GF254 and hexane/ethyl acetate,
9:1 as eluent).
monochromated Mo-K
tals were colorless, space group P1 (No. 1), a = 11.489(2), b =
11.669(2), c = 11.855(2) Å, = 104.31(4), b = 116.91(3), = 98.96(3)°,
calc = 1.222 gr/cm3,
l =
a radiation (k = 0.71073 Å). Obtained crys-
a
c
V = 1305.6(4) Å3, Z = 2, T = 25(2) °C,
q
4.2.2.6.
(2R/S,3R/S,4R/S)-2-(4-Methoxyphenyl)-1,3,4,5-tetraphenyl-
0.074 mmꢀ1. 4820 reflections were measured, 4228 unique (after
merging Friedel pairs) which were used in all least squared calcu-
pentane-1,5-dione 5a. Yield: 35%, mp 211–213 °C. 1H NMR (CDCl3,
500 MHz): d 3.65 (s, 3H, CH3O), 4.80 (dd, J = 6.9 and 10.5 Hz, 1H, H-
3), 4.98 (d, J2,3 = 6.9 Hz, 1H, H-2), 5.21 (d, J3,4 = 10.5, 1H, H-4), 6.90–
7.40 (m, 17H, H–Ar), 6.58 (d, J = 8.7 Hz, 2H), 6.90 (d, J = 8.7 Hz, 2H),
7.42 (d, J = 7.7 Hz, 2H), 7.58 (d, J = 7.8 Hz, 2H), 7.70 (d, J = 7.8 Hz,
2H) ppm. 13C NMR (CDCl3, 75 MHz: d 51.4 (C-3), 55.5 (C-2), 59.1
(C-4), 55.7, 114.1, 126.8, 128.1, 128.4, 128.7, 128.8, 129.0, 129.1,
129.5, 130.6, 131.0, 132.0, 133.0, 133.3, 137.1, 137.3, 138.0,
141.0, 159.0, 199.2 (C-1 CO), 199.3 (C-5 CO) ppm. MS: m/z (%)
510 (M+, 1), 405 (1), 330 (4), 315 (3), 314 (4), 225 (4), 210 (12),
197 (4), 180 (4), 167 (5), 165 (8), 152 (4), 121 (2), 106 (8), 105
(100), 91 (2), 77 (27), 51 (4).
lations, R1(F) = 0.088 (for 2076 reflections with F2o > 2
r
ðF2oÞ),
x
R2(F2) = 0.25 for all unique reflections. The absolute stereochem-
istry cannot be directly determined from the X-ray data, so the as-
signed stereochemistry character to molecules C-I and C-II is
arbitrary. CCDC reference number 644495.
4.2.2.2. 3-(4-Methoxyphenyl)-1,2,4,5-tetraphenylpentane-1,5-dione
2. General procedure
A was carried out with deoxybenzoin
(0.40 g, 2.04 mmol), 4-methoxybenzaldehyde (0.28 g, 2.04 mmol)
in absolute alcohol (2 mL) and NaMeO/MeOH 25% (0.2 mL) affor-
ded 2 as white solid (0.46 g, 88%), mp 232–233 °C (acetone) (Lit.
[6] 242 °C). 1H NMR (CDCl3, 300 MHz): d 3.63 (s, 3H, CH3O), 4.79
(dd, J = 7.0 and 10.5 Hz, 1H, H-3), 5.01 (d, J2,3 = 7.0 Hz, 1H, H-2),
5.18 (d, J3,4 = 10.5 Hz, 1H, H-4), 6.52 (d, J = 8.6 Hz, 2H), 6.95–7.38
(m, 16H, H–Ar), 7.43 (d, J = 8.3 Hz, 2H); 7.60 (d, J = 7.9 Hz, 2H),
7.72 (d, J = 7.9 Hz, 2H) ppm. 13C NMR (CDCl3, 75 MHz : d 50.0 (C-
3), 54.9 (C-2), 58.5 (C-4), 55.8, 112.8, 126.7, 127.7, 128.0, 128.2,
128.3, 128.4, 128.8, 130.9, 132.4, 132.2, 132.5, 136.5, 136.6,
136.7, 137.2, 157.6, 198.6 (C-1 CO), 198.7 (C-5 CO) ppm.
4.2.2.7.
(2R/S,3S/R,4R/S)-2-(4-Methoxyphenyl)-1,3,4,5-tetraphenyl-
pentane-1,5-dione 5b. Yield: 30%, mp 206–208 °C. 1H NMR (CDCl3,
500 MHz): d 3.63 (s, 3H, CH3O), 4.91 (dd, J = 8.1 and 10.5 Hz, 1H,
H-3), 5.03 (d, J2,3 = 8.1 Hz, 1H, H-4), 5.13 (d, J3,4 = 10.5 Hz, 1H, H-
2), 6.90–7.40 (m, 19H, H–Ar), 6.58 (d, J = 8.6 Hz, 2H), 7.62 (d,
J = 7.9 Hz, 2H), 7.68 (d, J = 7.9 Hz, 2H) ppm. 13C NMR (CDCl3,
75 MHz): d 51.6 (C-3), 56.9 (C-4), 59.2 (C-2), 55.7, 114.8, 126.7,
127.3, 128.2, 128.5, 128.6, 128.9, 128.9, 129.0, 130.5, 130.9,
132.3, 133.0, 133.1, 137.3, 137.6, 137.9, 141.4, 159.8, 198.9 (C-5
CO), 199.2 (C-1 CO) ppm. MS: m/z (%) 510 (M+, 2), 405 (1), 330
(3), 315 (5), 314 (15), 225 (3), 210 (4), 197 (4), 180 (4), 167 (7),
165(8), 152 (5), 121 (2), 106 (7), 105 (100), 91 (2), 77 (26), 51 (5).
4.2.2.3.
3-(3,4-Dimethoxyphenyl)-1,2,4,5-tetraphenylpentane-1,5-
dione 3. General procedure A was carried out with deoxybenzoin
(0.39 g, 2.00 mmol), 3,4-dimethoxybenzaldehyde (0.30 g, 2.00
mmol) in absolute alcohol (2 mL) and NaMeO/MeOH 25%
(0.2 mL) afforded 3 as white solid (0.43 g, 80%), mp: 188–190 °C
(EtOH); (Lit. [6] 190 °C). 1H NMR (CDCl3, 300 MHz): d 3.56 (s, 3H,
CH3O), 3.73 (s, 3H, CH3O), 4.80 (dd, J = 6.5 y 10.9 Hz, 1H, H-3),
4.99 (d, J2,3 = 6.5 Hz, 1H, H-2), 5.23 (d, J3,4 = 10.9 Hz, 1H, H-4),
6.43 (s, 1H), 6.54 (d, J = 8.5 Hz, 1H,), 6.80–7.40 (m, 15H, H–Ar),
7.48 (d, J = 7.3 Hz, 2H); 7.62 (d, J = 7.3 Hz, 2H), 7.75 (d, J = 7.3 Hz,
2H) ppm. 13C NMR (CDCl3, 75 MHz: d 50.3 (C-3), 55.4 (C-2), 57.8
(C-4), 55.5, 55.8, 110.1, 113.5, 122.2, 126.8, 127.7, 128.0, 128.1,
128.3, 128.4, 128.9, 130.2, 130.3, 132.37, 132.4, 132.6, 136.5,
136.6, 137.3, 147.0, 147.4, 198.6 (C-1 CO), 198.7 (C-5 CO) ppm.
4.2.2.8. (4-Metoxyphenyl)-1-phenylethanone 6. This compound was
prepared using 3-(4-methoxyphenyl)-2-phenyl-2-hydroxypropa-
noic acid and red lead oxide in glacial acetic acid as described
[10]. Yield: 58%, mp 98–99 °C (EtOH) (Lit. [10] 96 °C; Lit. [11]
92 °C). 1H NMR (CDCl3, 300 MHz): d 3.86 (s, 3 H, CH3O), 4.24 (s, 2
H, 2-H), 6.93 (d, J2,3 = 6.9, 2 H, H–Ar), 7.24–7.34 (m, 5 H, H–Ar),
8.00 (d, J = 6.9, 2 H) ppm.
4.2.2.9. (E)-1,2,3-Triphenylpropen-1-one 7. This compound was ob-
tained as a mixture of (E)/(Z) isomers (1:2.4) employing a previ-
ously described methodology [12]. The (E)-isomer, yield: 31%,
mp: 97–99 °C (bencene/hexane) (Lit. [12] 96.5–97.5 °C) was iso-
lated by chromatographic column employing benzene/hexane,
4:1 as eluent. 1H NMR (CDCl3, 300 MHz): d 7.05 (d, J = 8.0 Hz, 2H,
H–Ar), 7.11–7.49 (m, 12H, H–Ar), 7.82 (d, J = 7.9 Hz, 2H, H-
2) ppm. 13C NMR (CDCl3, 75 MHz: d 127.9, 128.3, 128.8, 129.0,
129.7, 129.8, 130.3, 132.2, 134.8, 136.5, 138.2, 140.2, 140.8, 197.7
(CO) ppm.
4.2.2.4. 2,4-bis-(4-Methoxyphenyl)-1,3,5-triphenylpentane-1,5-dione
4. General procedure A was carried out with 2-(4-metoxyphe-
nyl)-1-phenylethanone (6) (0.20 g, 0.82 mmol), benzaldehyde
(0.086 g, 0.82 mmol) in absolute alcohol (1 mL) and NaMeO/MeOH
25% (0.1 mL) afforded 4 as white solid (0.17 g, 72%), mp: 207–
209 °C (EtOH). 1H NMR (CDCl3, 300 MHz): d 3.64 (s, 6H, CH3O),
4.83 (dd, J = 7.6 and 10.5 Hz, 1H, H-3), 4.97 (d, J2,3 = 7.6 Hz, 1H,
H-2), 5.11 (d, J3,4 = 10.5 Hz, 1H, H-4), 6.92–7.02 (m, 4H, H–Ar),
6.59 (t, J = 8.6 Hz, 4H), 7.03 (d, J = 6.9 Hz, 2H), 7.21–7.39 (m, 9H),
7.61 (d, J = 7.4 Hz, 2H), 7.69 (d, J = 7.2 Hz, 2H) ppm. 13C NMR
(CDCl3, 75 MHz: d 50.7 (C-3), 54.9 (C-2), 58.4 (C-4), 55.0, 113.4,
126.1, 127.4, 127.7, 128.0, 128.2, 128.3, 128.4, 128.4, 128.8,
130.0, 130.3, 131.3, 132.3, 132.5, 136.4, 136.6, 137.2, 140.3,
158.3, 198.5 (C-1 CO), 198.6 (C-5 CO) ppm. MS: m/z (%) 540 (M+,
1), 435 (1), 331 (2), 330 (6), 315 (2), 227 (8), 226 (48), 225 (34),
211 (2), 210 (13), 198 (2), 197 (16), 167 (2), 166 (3), 165 (6), 153
(3), 152 (3), 121 (3), 106 (7), 105 (100), 91 (2), 78 (2), 77 (21), 51
(4).
Acknowledgements
This work was supported by the Universidad Nacional de Luján.
The authors thank Ms. E.V. Drago for technical contribution and
PhD G.Y. Moltrasio for valuable criticism.
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5a and 5b. General procedure B was carried out with a mixture

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125
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