Synthesis of mono-, di-, and tri-3,4-dimethoxycinnamoyl-1,5-γ- quinides

Article abstract of DOI:10.1002/ejoc.201301657

Tri-3,4-dimethoxycinnamoyl-1,5-γ-quinide was synthesized and fully characterized by a direct synthesis from quinic acid and a large excess of 3,4-dimethoxycinnamoyl chloride. Mono-and di-3,4-dimethoxycinnamoyl-1,5-γ- quinides were also obtained from the direct coupling of 1,5-γ-quinide and 3,4-dimethoxycinnamoyl chloride in different molar ratios. Moreover, a hypothetical mechanism of the direct lactonization is proposed. Mono-, di-, and tri-3,4-dimethoxycinnamoyl-1,5-γ-quinides have been synthesized from 1,5-γ-quinide and 3,4-dimethoxycinnamoyl chloride in different molar ratios. The only triester quinide was also easily obtained by a direct synthesis from D-(-)-quinic acid in the presence of an excess of the acyl chloride. Copyright

Full text of DOI:10.1002/ejoc.201301657

FULL PAPER
DOI: 10.1002/ejoc.201301657
Synthesis of Mono-, Di-, and Tri-3,4-dimethoxycinnamoyl-1,5-γ-quinides
Valentina Sinisi,*[a] Katarína Boronová,[b] Silvia Colomban,[c] Luciano Navarini,[d]
Federico Berti,[a] and Cristina Forzato*[a]
Keywords: Quinides / Coffee / Chlorogenic acids / Acylation / Lactones / Cinnamoyl derivatives
Tri-3,4-dimethoxycinnamoyl-1,5-γ-quinide was synthesized
and fully characterized by a direct synthesis from quinic acid
and a large excess of 3,4-dimethoxycinnamoyl chloride.
Mono- and di-3,4-dimethoxycinnamoyl-1,5-γ-quinides were
also obtained from the direct coupling of 1,5-γ-quinide and
3,4-dimethoxycinnamoyl chloride in different molar ratios.
Moreover, a hypothetical mechanism of the direct lacton-
ization is proposed.
Introduction
Chlorogenic acids (CGAs) are secondary metabolites in
many plants, particularly coffee. Green coffee beans are rich
in these compounds and their amount, on a dry matter ba-
sis, ranges from 4 to 8.4% for Coffea arabica and from 7 to
14.4% for Coffea canephora (usually referred to as Ro-
busta).[1–3] They are esters of quinic acid with different cin-
namic acids, such as caffeic, ferulic, and p-coumaric acids,
which acylate the hydroxy groups at the 3-, 4-, or 5-posi-
tions of d-(–)-quinic acid to produce a series of monoesters.
Diesters (with the same cinnamoyl moiety or with different
cinnamic acids) or even triesters are also found, but no acyl-
ation at C-1 seems to occur (Figure 1). Over 60 chlorogenic
acids and their derivatives have been identified, although
full characterization was not performed for all of them.
Many such compounds were determined only by LC–MS
analysis, and their structural assignments were made only
by analysis of the fragmentation pattern of their MS spec-
tra.[4]
Figure 1. Molecular structure of d-(–)-quinic acid and of its esters
and lactones. The IUPAC numbering system was adopted.[9]
lactonization reactions, that lead to a multiplicity of deriva-
tives, including the chlorogenic acid lactones (CGLs), also
known as quinides.[5–7] The bitter threshold level of the
quinides was tested by means of human sensory studies and
it ranges from 9.8 to 180 mmol/L.[8]
As these compounds contribute to the bitterness of the
beverage,[6–8,10,11] the identification and the evaluation of
the total amounts of quinides is a central focus for the cof-
fee industry to optimize the roasting process and to obtain
the best taste profile. Great attention has been dedicated to
the identification of these lactones in the literature, and very
recently three chlorogenic acid lactones have been isolated
and fully characterized.[12]
Many studies have demonstrated that the consumption
of CGAs in the human diet is connected with a series of
health benefits: they are antioxidant, anti-inflammatory,
and antispasmodic[13–17] and can reduce the relative risk of
cardiovascular diseases, type2 diabetes, and Alzheimer’s
disease.[18–20]
The taste quality of a coffee beverage depends not only
on the geographical region of origin of the beans but also
on the kind of roasting process used. For example, during
the roasting process, the nonbitter 5-O-caffeoylquinic acid
present in the green coffee bean undergoes different trans-
formations, such as transesterification, epimerization, and
[a] Dipartimento di Scienze Chimiche e Farmaceutiche, Università
degli Studi di Trieste,
Via L. Giorgieri 1, 34127 Trieste, Italy
E-mail: valentina.sinisi@phd.units.it
cforzato@units.it
http://www.dsch.units.it/
[b] Department of Chemistry, Faculty of Natural Sciences,
University of Ss. Cyril and Methodius,
Nám. J. Herdu 2, SK-917 01 Trnava, Slovakia
[c] Aromalab, illycaffè S.p.A., AREA Science Park,
Padriciano 99, 34012 Trieste, Italy
[d] illycaffè S.p.A.,
Via Flavia 110, 34147 Trieste, Italy
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201301657.
Eur. J. Org. Chem. 2014, 1321–1326
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1321

V. Sinisi, K. Boronová, S. Colomban, L. Navarini, F. Berti, C. Forzato
FULL PAPER
The biological activity of chlorogenic acid lactones was ence of a large excess of triethylamine and 4-dimethyl-
also studied, and they protect neuronal cells against oxidat- aminopyridine (DMAP) as catalyst.[28,29] At a 1:3.5 lactone/
ive stress by modulating the extracellular signal-regulated acyl chloride molar ratio, the conversion of 1,5-γ-quinide
kinase (ERK1/2) and c-Jun N-terminal kinase (JNK) sig- 2 into dimethoxycinnamic esters was quantitative, and two
naling pathways. In addition, 4-diferuloyl-1,5-quinide, 3,4- products were obtained: the triacylated quinide 3 and the
dicaffeoyl-1,5-quinide, and 3,4-dicoumaroyl-1,5-quinide in- diester 4 (bearing the 3,4-dimethoxycinnamoyl groups at
hibit the adenosine transporter at low micromolar concen- the 3- and 4-positions) in a 1:0.4 molar ratio. The two prod-
tration, whereas the corresponding 3- and 4-mono caffeoyl- ucts could be easily separated by flash chromatography, and
and feruloylquinides were one to two orders of magnitude the structures of pure 3 and 4 could be assigned on the
less active.[21–23]
basis of bidimensional NMR analysis and IR and MS data.
1
Moreover, the two strains of coffee, Coffea arabica (Ara- In the H NMR spectrum of 3, three 3,4-dimethoxycinn-
bica coffee) and Coffea canephora (Robusta coffee), differ amoyl groups were found, so necessarily all the hydroxy
in content and composition of CGAs; as Robusta is cheaper groups on the quinide reacted. The IR spectra of both com-
and of lower quality than Arabica, it is important to ident- pounds show a strong peak at 1800 cm–1 and, thus, confirm
ify compounds that are present in Robusta only for authen- the presence of a five-membered lactone. However, the cor-
tication purposes. Under this point of view, a complete responding molecular ion can be observed only in the ESI+
characterization of the CGAs and their derivatives in both MS spectra, whereas in ESI– mode, signals for the corre-
green and roasted coffee beans becomes essential. The avail- sponding acyl quinic acids that result from the opening of
ability of standards is one of the main goals to be achieved the lactone rings of 3 and 4 were obtained. This behavior
to set up rapid analytical methodologies to typify coffee.
was found for the negative-mode spectra for all of the lact-
Recently, new classes of CGAs in green coffee beans were ones and should be considered for the analysis of mixtures
characterized by LC–MSn.[24] These CGAs could help to from natural sources, as it could lead to incorrect assign-
distinguish between the two types of coffee. One of these is ments.
the dimethoxycinnamic acid family (DMQs): these com-
At a 1:2.2 molar ratio, three main products could be iso-
pounds probably undergo the same thermal degradations lated: triester 3, which is also in this case the most abundant
of the other CGAs during the roasting process, but al- one, the C-3 monoester 5, and the diester 4. Three other
though the acids were identified in green coffee, their lact- products could also be recognized, namely, 1,3-O-bis[3,4-
ones are still undetected in the roasted beans. Therefore, we (dimethoxy)cinnamoyl]-1,5-γ-quinide (6), 1,4-O-bis[3,4-(di-
have focused our attention on the dimethoxycinnamoyl-γ- methoxy)cinnamoyl]-1,5-γ-quinide (7), and 4-O-[3,4-(di-
quinides to use them as standards for roasted coffee extracts methoxy)cinnamoyl]-1,5-γ-quinide (8, Scheme 1). The rela-
analysis by HPLC and, in case of their identification, to tive abundance of the compounds obtained, determined by
study their bitter threshold level and their possible bio- NMR analysis, is reported in Table 1 together with the most
logical activity.
significant signals related to the protons of the quinic core.
Purification by flash chromatography on silica gel al-
As a result of these investigations, in the present work,
we propose a simple synthesis of different regioisomers of lowed us to obtain pure samples of 3, 4 and 5, whereas 6,
mono-, di-, and tri-DMQs.
7, and 8 were recovered as a mixture.
We have also performed a direct coupling between d-(–)-
quinic acid and acyl chloride 1 in 1:1 and 1:2 molar ratios.
The reactions were performed in the presence of triethyl-
Results and Discussion
To obtain the desired compounds, we decided to perform amine and DMAP in dichloromethane at room tempera-
a classical coupling reaction between an acyl chloride and ture, as in the previous cases.
an alcohol in the presence of a base and a catalytic amount
Such reactions lead again to the formation of quinide
compounds rather than to quinic acid derivatives, and the
of a suitable nucleophile to accelerate the process.[25,26]
3,4-Dimethoxycinnamoyl chloride (1) was synthesized triacyl derivative 3 was always the most abundant one. At
from 3,4-dimethoxycinnamic acid and thionyl chloride in a 1:1 molar ratio, we obtained a mixture of 3, 6, 7, and 1-
50% yield after crystallization from toluene. In a first ap- O-[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide [9; Scheme 3,
proach, chloride 1 was used to acylate lactone 2, which was diagnostic NMR signals in CDCl3: δ = 4.02 (3-H), 4.18 (4-
synthesized from quinic acid under acidic catalysis by fol- H), and 4.93 (5-H) ppm; 42, 38, 8, and 12%, respectively],
lowing a literature procedure[27] with some modifications: whereas at a 1:2 molar ratio, only 3, 6, and 7 (63, 28, and
we tried to recrystallize the brown sticky residue obtained 9%, respectively) formed; no unreacted d-(–)-quinic acid
from evaporation of the reaction mixture by heating it un- was found in the crude mixture, but it was realistically
der reflux in ethyl acetate, as suggested in the adopted pro- washed away during the workup.
cedure, but this method was not successful; the pure prod-
This result is rather surprising, as similar methodologies
uct was obtained by the addition of methanol to precipitate were followed by other authors to prepare chlorogenic acids
a white solid, which was collected by filtration of the brown of the same family,[24,30] rather than their lactonization
solution.
products. We have, therefore, studied the reaction in more
The reaction of lactone 2 with chloride 1 was underper- detail with the aim to set up a protocol for the direct and
formed at different molar ratios of the reactants in the pres- simultaneous acylation and lactonization of quinic acid. We
1322
www.eurjoc.org
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2014, 1321–1326

Synthesis of Mono-, Di-, and Tri-3,4-dimethoxycinnamoyl-1,5-γ-quinides
Scheme 1. Synthesis of 3–8.
Table 1. Composition of the mixture obtained from 2 and 1 at 1:2.2 add it slowly in its solid form; indeed, its hydrolysis is easier
1
molar ratio and diagnostic H NMR signals (δ in CDCl3).
in solution.
The lactonization of quinic acid to yield quinide 3 was
unexpected, and we have verified that the large excess of
base used during the reaction does not lead to lactone for-
mation with d-(–)-quinic acid alone under the same condi-
tions.
Based on a literature procedure,[24] we tried the direct
coupling between d-(–)-quinic acid and the acyl chloride 1
in a 1:0.5 molar ratio in the presence of only 1 equiv. of
Amount [%]
3-H [ppm]
4-H [ppm]
5-H [ppm]
3
4
5
6
7
8
36
11
23
18
7
5.38
5.29
4.92
5.19
4.25
4.17
5.73
5.68
4.30
4.94
5.44
5.40
5.01
4.94
4.75
4.45
5.04
4.95
5
have, thus, found that by increasing the molar excess of triethylamine and without DMAP to verify if the large ex-
chloride 1 up to 1:7 to force the acylation of all the hydroxy cess of base promoted the lactonization reaction and also
groups, the triester quinide 3 was obtained as a unique if the presence of DMAP was decisive. On the contrary to
product in 75% yield, calculated after purification by flash what the other authors found, we obtained only quinide 9
chromatography (Scheme 2). To better quantify the real and the 1-O-[3,4-(dimethoxy)cinnamoyl]quinic acid (10) in
equivalents of acyl chloride in the mixture, we decided to a 1:1.4 ratio (Scheme 3) together with unreacted d-(–)-
Eur. J. Org. Chem. 2014, 1321–1326
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1323

V. Sinisi, K. Boronová, S. Colomban, L. Navarini, F. Berti, C. Forzato
FULL PAPER
Scheme 2. Direct synthesis of 3.
Scheme 3. Synthesis of 9 and 10.
quinic acid and 3,4-dimethoxycinnamic acid anhydride, as
Moreover, from d-(–)-quinic acid, all the obtained prod-
1
evidenced by H NMR spectroscopy of the crude mixture. ucts are C-1-acylated compounds, both chlorogenic acid
The 3,4-dimethoxycinnamic acid anhydride was found only and quinides, and the direct lactonization in the presence
in other crude mixtures of attempted coupling without of acyl chloride may represent a useful way to synthesize
DMAP, but never when the catalyst was added.
such quinides. Finally, we have also observed that ESI+
On the basis of the result of this uncatalyzed reaction mode MS spectra show the quinide molecular ions, whereas
and the fact that all of the coupling products obtained in in the ESI– mode, m/z values corresponding to the esterified
the direct reaction with d-(–)-quinic acid are functionalized acids appear and suggest that the molecules have been hy-
at the 1-position, we propose a lactonization mechanism drolyzed during the analysis.
involving two molecules of acyl chloride (Scheme 4) that
react sequentially with the carboxylic group of quinic acid
Experimental Section
to give an anhydride: the first leads to the esterification of
C-1–OH, and the second activates the five- membered ring
formation (Scheme 4).
Materials and Instruments: All reagents and solvents for the synthe-
ses were purchased from Sigma–Aldrich and used without further
purification. Thin layer chromatographic (TLC) analyses were per-
formed on Merck 60 F254 silica gel plates, and Merck silica gel
60 (0.040–0.063 mm, 230–400 mesh ASTM) was used for column-
chromatographic purifications (flash chromatography). Melting
points were measured with a Sanyo Gallenkamp apparatus. The
optical activity measurements ([α]) were performed with a Perkin–
Elmer 241 polarimeter at the wavelength of sodium D band (λ =
589 nm) by using a quartz cuvette with a length of 10 cm (l =
1
1 dm). The H and 13C NMR spectra were recorded with a Varian
500 spectrometer (referenced to the residual solvent peaks: δ =
7.26 ppm for CDCl3 and 3.31 ppm for CD3OD). Electrospray Ion-
ization (ESI) mass spectrometry measurements were performed
with an Esquire 4000 (Bruker-Daltonics) spectrometer. Infrared
spectra (IR) were recorded with an Avatar 320-IR FTIR (Thermo-
Nicolet) spectrometer with thin films of sample on NaCl crystal
windows. Elemental analyses (EA) were performed with a Flash
2000 Series CHNS/O Analyzer (Thermo Fisher Scientific).
Scheme 4. Hypothetical mechanism of the direct lactonization.
Conclusions
We have proposed a simple method to obtain quinides
with different acylation patterns. These quinides can be eas-
ily separated and can be used as standards in coffee analy-
sis. The same procedure could be applied to the synthesis
of caffeoyl-, feruloyl-, and p-coumaroyl-γ-quinides, con-
sidering that the phenolic groups should be previously pro-
tected and that to obtain the desired compound a deprotec-
tion step after the coupling reaction is needed.
1,3,4-O-Tris[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide (3), 3,4-O-
Bis[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide (4) and 3-O-[3,4-(Di-
methoxy)cinnamoyl]-1,5-γ-quinide (5)[31,32]
3,4-Dimethoxycinnamic Acid Chloride (1): A suspension of 3,4-di-
methoxy cinnamic acid (1.41 g, 4.76 mmol) in thionyl chloride
(2.4 mL, 33 mmol, added dropwise) was heated to 90 °C until a
homogeneous grey-green solution formed without gas development
1324
www.eurjoc.org
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2014, 1321–1326

Synthesis of Mono-, Di-, and Tri-3,4-dimethoxycinnamoyl-1,5-γ-quinides
(ca. 2 h). The unreacted thionyl chloride was removed under vac-
uum, and the olive-brown solid residue was recrystallized from tol-
uene (10 mL) and collected by filtration to afford the product as a
yellow solid (yield 50%), which was used immediately. 1H NMR
1,3,4-O-Tris[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide (3): This com-
pound was recovered from both the crude mixtures as an ochre
powder. Rf = 0.64 (dichloromethane/ethyl acetate 7:3, TLC stained
with UV lamp at 254 nm); M.p. 103–105 °C. [α]2D5 = +266.7 (c = 1,
(500 MHz, CDCl3): δ = 3.91 (s, 3 H, OCH3), 3.92 (s, 3 H, OCH3), CH2Cl2). 1H NMR (500 MHz, CDCl3): δ = 2.51 (ddd, Jgem
=
6.49 (d, J = 15.4 Hz, 1 H, 1-H), 6.89 (d, Jortho = 8.3 Hz, 1 H, 5-H),
7.02 (d, Jmeta = 1.9 Hz, 1 H, 8-H), 7.07 (dd, Jortho = 8.3 Hz, Jmeta
= 1.9 Hz, 1 H, 4-H), 7.75 (d, J = 15.4 Hz, 1 H, 2-H) ppm. 13C
NMR (125.4 MHz, CDCl3): δ = 55.88 (s, OCH3), 55.97 (s, OCH3),
110.11 (s, C-8), 111.11 (s, C-5), 119.57 (s, C-1), 124.57 (s, C-4),
125.90 (s, C-3), 149.37 (s, C-7), 150.79 (s, C-2), 152.66 (s, C-6),
11.7 Hz, J2-H
(dd, Jgem = 11.7 Hz, J
= 11.7 Hz, 1 H, 6-Hax), 3.13 (ddd, Jgem = 11.7, J
= 6.8 Hz, J2-H
= 2.5 Hz, 1 H, 2-Heq), 2.64
eq,3-H
eq,6-Heq
= 11.6 Hz, 1 H, 2-Hax), 2.89 (d, Jgem
2-Hax,3-H
= 6.1 Hz,
6-Heq,5-H
J6-H
= 2.5 Hz, 1 H, 6-Heq), 3.80 (s, 3 H, OCH3), 3.88 (s, 3 H,
eq,2-Heq
OCH3), 3.92 (s, 6 H, 2 OCH3), 3.93 (s, 6 H, 2 OCH3), 5.01 (dd,
J5-H,6-H = 6.1 Hz, J5-H,4-H = 5.1 Hz, 1 H, 5-H), 5.38 (ddd,
eq
165.84 (COCl) ppm. IR: ν = 2938, 2838, 2596, 2360, 1681, 1624,
J3-H,2-H = 11.6 Hz, J3-H,2-H = 6.8 Hz, J3-H,4-H = 4.7 Hz, 1 H, 3-
˜
ax
eq
1595, 1517, 1268, 1141, 1023 cm–1.
H), 5.73 (dd, J4-H,5-H = 5.1 Hz, J4-H,3-H = 4.7 Hz, 1 H, 4-H), 6.20
(d, J9-H,10-H = 15.9 Hz, 1 H, 9-H), 6.34 (d, J9ЈЈ-H,10ЈЈ-H = 15.9 Hz, 1
H, 9ЈЈ-H), 6.40 (d, J9Ј-H,10Ј-H = 15.8 Hz, 1 H, 9Ј-H), 6.77 (d, Jortho
= 8.3 Hz, 1 H, 13-H), 6.87 (2 d, Jortho = 8.3 Hz, 2 H, 13Ј-H and
1,5-γ-Quinide (2): d-(–)-Quinic acid (1.50 g, 7.83 mmol) and p-tolu-
enesulfonic acid monohydrate (165 mg, 0.37 mmol) were suspended
in a mixture of toluene (20 mL) and dry N,N-dimethylformamide
(DMF; stored over molecular sieves, 3.75 mL), and the mixture was
heated under reflux with a Dean–Stark apparatus for 20 h. The
solvent was removed under vacuum, and the brown sticky residue
was recrystallized from methanol (10 mL) and collected by fil-
tration to afford an ivory solid (yield 50%). Rf = 0.25 (dichloro-
methane/methanol 9:1, TLC stained with permanganate solution);
M.p. 170–172 °C. [α]2D5 = –29.7 (c = 1, CH3OH). 1H NMR
13ЈЈ-H), 6.95 (d, Jmeta = 1.8 Hz, 1 H, 16-H), 7.01 (dd, Jortho
=
8.3 Hz, Jmeta = 1.8 Hz, 1 H, 12-H), 7.07 (2 d, Jmeta = 1.8 Hz, 2 H,
16Ј-H and 16ЈЈ-H), 7.12 (2 dd, Jortho = 8.3 Hz, Jmeta = 1.8 Hz, 2 H,
12Ј-H and 12ЈЈ-H), 7.57 (d, J10-H,9-H = 15.9 Hz, 1 H, 10-H), 7.67
(d, J10Ј-H,9Ј-H = J10ЈЈ-H,9ЈЈ-H = 15.9 Hz, 2 H, 10Ј-H and 10ЈЈ-H) ppm.
13C NMR (125.4 MHz, CDCl3): δ = 33.87 (s, C-2), 34.71 (s, C-6),
55.78 (s, OCH3), 55.92 (s, OCH3), 55.93 (s, OCH3), 55.94 (s,
OCH3), 55.98 (s, OCH3), 56.01 (s, OCH3), 64.92 (s, C-4), 65.99 (s,
C-3), 73.97 (s, C-5), 76.57 (s, C-1), 109.54 (s, C-16Ј), 109.67 (s, C-
16ЈЈ), 109.77 (s, C-16), 110.93 (s, C-13), 111.02 (s, 2 C, C-13Ј and
C-13ЈЈ), 114.05 (s, C-9Ј), 114.24 (s, C-9ЈЈ), 114.37 (s, C-9), 122.81
(s, C-12), 123.08 (s, C-12Ј), 123.45 (s, C-12ЈЈ), 126.85 (s, C-11),
126.89 (s, C-11Ј), 127.01 (s, C-11ЈЈ), 146.01 (s, C-10), 146.66 (s, C-
10Ј), 146.86 (s, C-10ЈЈ), 149.14 (s, C-15), 149.27 (s, C-15ЈЈ), 149.32
(s, C-15Ј), 151.32 (s, C-14), 151.63 (s, C-14ЈЈ), 151.65 (s, C-14Ј),
165.15 (s, C-8), 165.27 (s, C-8ЈЈ), 165.51 (s, C-8Ј), 171.45 (s, C-7)
(500 MHz, CD3OD): δ = 1.87 (dd, Jgem = 11.4 Hz, J2-H
=
ax,3-H
10.9 Hz, 1 H, 2-Hax), 2.02 (ddd, Jgem = 11.4 Hz, J
= 6.6 Hz,
2-Heq,3-H
J2-H
J6-H
= 2.4 Hz, 1 H, 2-Heq), 2.23 (ddd, Jgem = 11.2 Hz,
eq,6-Heq
= 5.5 Hz, J6-H
= 2.4 Hz, 1 H, 6-Heq), 2.47 (d, Jgem
eq,5-H
eq,2-Heq
= 11.2 Hz, 1 H, 6-Hax), 3.70 (ddd, J
= 10.9 Hz, J3-H,2-H =
eq
3-H,2-Hax
6.6 Hz, J3-H,4-H = 3.9 Hz, 1 H, 3-H), 3.98 (dd, J4-H,5-H = 4.1 Hz,
J4-H,3-H = 3.9 Hz, 1 H, 4-H), 4.70 (dd, J
= 5.5 Hz, J5-H,4-H
5-H,6-Heq
= 4.1 Hz, 1 H, 5-H) ppm. 13C NMR (125.4 MHz, CD3OD): δ =
37.97 (s, C-6), 40.26 (s, C-2), 66.97 (s, C-4), 67.47 (s, C-3), 73.24 (s,
ppm. IR: ν = 2938.3, 1803.8, 1716.0, 1630.1, 1597.6, 1513.8, 1464.3,
˜
C-1), 78.01 (s, C-5), 179.69 (s, C-7) ppm. IR: ν = 3583.0, 3281.5,
˜
1421.9, 1262.6, 1138.4, 1023.1, 981.5, 734.3 cm–1. MS (ESI+): m/z
(%) = 767 (100) [M + Na]+. C40H40O14·1/2AcOEt (788.81): calcd.
C 63.95, H 5.62; found C 64.00, H 5.41.
2918.6, 1794.8, 1141.9, 1038.2, 979.3 cm–1. MS (ESI+): m/z (%) =
197 (100) [M + Na]+. C7H10O5 (174.15): calcd. C 48.28, H 5.79;
found C 48.26, H 5.90.
3,4-O-Bis[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide (4): This com-
pound was recovered as a yellow powder from the crude mixture
of the first coupling run. Rf = 0.35 (dichloromethane/ethyl acetate
7:3, TLC stained with UV lamp at 254 nm); M.p. 104–106 °C.
Coupling of 2 and 1: Compound 2 (181 mg, 1.04 mmol) was sus-
pended in CH2Cl2 (stored over CaCl2, 20 mL); DMAP (27 mg,
0.22 mmol) and Et3N (0.9 mL, 6.4 mmol) were added, and the
solution was cooled to 0 °C. Chloride 1 (796 mg, 3.5 mmol) was
slowly added, and the orange solution was stirred for 1 h at 0 °C
and then for 24 h at room temperature. The reaction mixture was
sequentially extracted with 1 m HCl (two times, 10 mL at a time),
2% NaHCO3 (12 mL), and brine (10 mL); the organic layer was
dried with Na2SO4, and the solvent was removed by vacuum evapo-
1
[α]2D5 = +219.4 (c = 0.5, CH2Cl2). H NMR (500 MHz, CDCl3): δ
= 2.26 (dd, Jgem = 11.9 Hz, J
= 11.7 Hz, 1 H, 2-Hax), 2.37
2-Hax,3-H
(ddd, Jgem = 11.9 Hz, J
= 6.8 Hz, J2-H
= 2.3 Hz, 1 H,
2-Heq,3-H
eq,6-Heq
2-Heq), 2.50 (ddd, Jgem = 11.9 Hz, J
= 5.6 Hz, J6-H
=
eq,2-Heq
6-Heq,5-H
2.3 Hz, 1 H, 6-Heq), 2.64 (d, Jgem = 11.9 Hz, 1 H, 6-Hax), 3.26 (br,
1 H, 1-OH), 3.79 (s, 3 H, OCH3), 3.87 (s, 3 H, OCH3), 3.91 (s, 3
1
ration. The crude product was analyzed by H NMR spectroscopy
and it was a mixture of esters 3 and 4 in a molar ratio of 1:0.4
(conversion of 1,5-γ-quinide in esters 100%).
H, OCH3), 3.92 (s, 3 H, OCH3), 4.94 (dd, J
= 5.6 Hz,
5-H,6-Heq
J5-H,4-H = 5.1 Hz, 1 H, 5-H), 5.29 (ddd, J3-H,2-H = 11.7 Hz,
ax
J3-H,2-H = 6.8 Hz, J3-H,4-H = 4.8 Hz, 1 H, 3-H), 5.68 (dd, J4-H,5-H
eq
= 5.1 Hz, J4-H,3-H = 4.8 Hz, 1 H, 4-H), 6.20 (d, J9-H,10-H = 15.9 Hz,
1 H, 9-H), 6.38 (d, J9Ј-H,10Ј-H = 15.8 Hz, 1 H, 9Ј-H), 6.77 (d, Jortho
= 8.3 Hz, 1 H, 13-H), 6.87 (d, Jortho = 8.3 Hz, 1 H, 13Ј-H), 6.94 (d,
Jmeta = 1.8 Hz, 1 H, 16-H), 6.96 (dd, Jortho = 8.3 Hz, Jmeta = 1.8 Hz,
The same coupling was performed with a starting molar ratio be-
tween 2 and 1 of 1:2.2 (2 172.5 mg, 1.0 mmol; 1 497 mg, 2.2 mmol;
DMAP 24.5 mg, 0.2 mmol; Et3N 0.85 mL, 6 mmol; 20 mL of
CH2Cl2). In this case, the crude product was a mixture of esters
mainly composed of 3, 5, 1,3-O-bis[3,4-(dimethoxy)cinnamoyl]-1,5-
γ-quinide (6; 36, 23, and 18%, respectively) and minor amounts of
4, 1,4-O-bis[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide (7), and 4-O-
[3,4-(dimethoxy)cinnamoyl]-1,5-γ-quinide (8, Ͻ10% each; conver-
sion of 1,5-γ-quinide in esters 100%).
1 H, 12-H), 7.05 (d, Jmeta = 1.8 Hz, 1 H, 16Ј-H), 7.11 (dd, Jortho
=
8.3 Hz, Jmeta = 1.8 Hz, 1 H, 12Ј-H), 7.56 (d, J10-H,9-H = 15.9 Hz, 1
H, 10-H), 7.67 (d, J10Ј-H,9Ј-H = 15.9 Hz, 1 H, 10Ј-H) ppm. 13C NMR
(125.4 MHz, CDCl3): δ = 36.90 (s, C-2), 37.42 (s, C-6), 55.76 (s,
OCH3), 55.90 (s, OCH3), 55.92 (s, OCH3), 55.98 (s, OCH3), 64.56
(s, C-4), 66.15 (s, C-3), 72.01 (s, C-1), 73.95 (s, C-5), 109.70 (s, C-
16Ј), 109.74 (s, C-16), 110.90 (s, C-13), 111.03 (s, C-13Ј), 114.02 (s,
C-9Ј), 114.39 (s, C-9), 122.81 (s, C-12), 123.08 (s, C-12Ј), 126.79 (s,
C-11), 126.99 (s, C-11Ј), 145.99 (s, C-10), 146.61 (s, C-10Ј), 149.10
(s, C-15), 149.35 (s, C-15Ј), 151.29 (s, C-14), 151.62 (s, C-14Ј),
Both the crude mixtures were purified by flash chromatography on
silica gel (glass column 2.5ϫ35 cm, elution in gradient from
CH2Cl2/ethyl acetate 7:3 to 6:4 v/v); 3, 4, and 5 were obtained as
pure products.
Eur. J. Org. Chem. 2014, 1321–1326
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1325

V. Sinisi, K. Boronová, S. Colomban, L. Navarini, F. Berti, C. Forzato
FULL PAPER
[2] G. H. D. Van der Stegen, J. Van Duijin, Proc. 9th Int. Sci. Coll.
Coffee (London), Association Scientifique Internationale du
Cafè, Paris, 1980, 107–112.
[3] A. Farah, C. M. Donangelo, Braz. J. Plant Physiol. 2006, 18,
23–36.
[4] M. N. Clifford, J. Sci. Food Agric. 2000, 80, 1033–1043.
[5] A. Farah, T. de Paulis, L. C. Trugo, P. R. Martin, J. Agric. Food
Chem. 2005, 53, 1505–1513.
[6] K. Schrader, A. Kiehne, U. H. Engelhardt, H. G. Maier, J. Sci.
Food Agric. 1996, 71, 392–398.
165.39 (s, C-8), 165.54 (s, C-8Ј), 176.78 (s, C-7) ppm. IR: ν =
˜
3462.44, 2938.4, 1796.6, 1714.5, 1630.2, 1597.7, 1513.7, 1464.2,
1261.5, 1138.1, 1065.1, 1022.2, 981.5, 734.3 cm–1. MS (ESI+): m/z
(%) = 577 (100) [M + Na]+. C29H30O11·1/2H2O (563.54): calcd. C
61.81, H 5.54; found C 61.94, H 5.48.
3-O-[3,4-(Dimethoxy)cinnamoyl]-1,5-γ-quinide (5): This compound
was recovered from the crude mixture of the second coupling run:
the last fractions collected from the column were a blend of 5 and
8; recrystallization from CHCl3 gave the pure product as a white
solid. Rf = 0.16 (dichloromethane/ethyl acetate 7:3, TLC stained
with UV lamp at 254 nm); M.p. 188–189 °C. [α]2D5 = +3.2 (c = 0.5,
[7] B. M. Scholz, H. G. Maier, Z. Lebensm.-Unters. Forsch. 1990,
190, 132–134.
[8] O. Frank, S. Blumberg, G. Krümpel, T. Hofmann, J. Agric.
CH3OH). 1H NMR (500 MHz, CD3OD): δ = 2.09 (dd, Jgem
=
Food Chem. 2008, 56, 9581–9585.
[9] IUPAC Commission on the Nomenclature of Organic Chemis-
try (CNOC) and IUPAC-IUB Commission on Biochemical
Nomenclature (CBN), Biochem. J. 1976, 153, 23–31.
[10] O. Frank, G. Zehentbauer, T. Hofmann, Eur. Food Res. Tech-
nol. 2006, 222, 492–508.
[11] R. Jaiswal, M. F. Matei, F. Ullrich, N. Kuhnert, J. Mass Spec-
trom. 2011, 46, 933–942.
[12] N. Kaiser, D. Birkholz, S. Colomban, L. Navarini, U. H. Engel-
hardt, J. Agric. Food Chem. 2013, 61, 6937–6941.
[13] Y. Kono, K. Kobayashi, S. Tagawa, K. Adachi, A. Ueda, Y.
Sawa, H. Shibata, Biochim. Biophys. Acta 1997, 1335, 335–342.
[14] M. D. Castilho, J. M. Ames, M. Gordon, J. Agric. Food Chem.
2002, 50, 3698–3703.
[15] H. Kikuzaki, M. Hisamoto, K. Hirose, K. Akiyama, H. Tanig-
uchi, J. Agric. Food Chem. 2002, 50, 2161–2168.
[16] M. D. Santos, M. C. Almeida, N. P. Lopes, G. E. P. Souza,
Biol. Pharm. Bull. 2006, 54, 8738–8743.
11.7 Hz, J2-H
11.7 Hz, J2-H
(ddd, Jgem = 11.6 Hz, J
6-Heq), 2.57 (d, Jgem = 11.6 Hz, 1 H, 6-Hax), 3.87 (s, 6 H, 2 OCH3),
4.30 (dd, J4-H,5-H = 4.8 Hz, J4-H,3-H = 4.9 Hz, 1 H, 4-H), 4.75 (dd,
= 11.6 Hz, 1 H, 2-Hax), 2.17 (ddd, Jgem =
ax,3-H
= 6.2 Hz, J2-H
= 2.4 Hz, 1 H, 2-Heq), 2.30
eq,3-H
eq,6-Heq
= 5.5 Hz, J6-H
= 2.4 Hz, 1 H,
6-Heq,5-H
eq,2-Heq
J5-H,6-H = 5.5 Hz, J5-H,4-H = 4.8 Hz, 1 H, 5-H), 4.92 (ddd,
eq
J3-H,2-H = 11.6 Hz, J3-H,2-H = 6.2 Hz, J3-H,4-H = 4.9 Hz, 1 H, 3-
ax
eq
H), 6.44 (d, J9-H,10-H = 15.9 Hz, 1 H, 9-H), 6.98 (d, Jortho = 8.2 Hz,
1 H, 13-H), 7.18 (dd, Jortho = 8.2 Hz, Jmeta = 1.9 Hz, 1 H, 12-H),
7.22 (d, Jmeta = 1.9 Hz, 1 H, 16-H), 7.71 (d, J10-H,9-H = 15.9 Hz, 1
H, 10-H) ppm. 13C NMR (125.4 MHz, CD3OD): δ = 36.89 (s, C-
2), 37.77 (s, C-6), 56.43 (s, OCH3), 56.51 (s, OCH3), 64.83 (s, C-4),
70.26 (s, C-3), 73.01 (s, C-1), 77.64 (s, C-5), 111.58 (s, C-16), 112.65
(s, C-13), 116.05 (s, C-9), 124.09 (s, C-12), 128.78 (s, C-11), 146.99
(s, C-10), 150.81 (s, C-15), 152.98 (s, C-14), 167.74 (s, C-8), 178.87
(s, C-1) ppm. IR: ν = 3583.1, 2360.4, 1787.9, 1707.9, 1636.4, 1597.4,
˜
[17] A. Trute, J. Gross, E. Mutschler, A. Nahrstedt, Planta Med.
1997, 63, 125–129.
[18] T. Ranheim, B. Halvorsen, Mol. Nutr. Food Res. 2005, 49, 274–
284.
1516.9, 1264.5, 1135.0, 1020.9, 812.0, 665.7 cm–1. MS (ESI+): m/z
(%) = 387 (100) [M + Na]+. C18H20O8·1/2H2O (373.35): calcd. C
57.91, H 5.67; found C 58.08, H 5.46.
[19] E. Salazar-Martinez, W. C. Willet, A. Ascherio, J. E. Manson,
M. F. Leitzmann, M. J. Stampfer, F. B. Hu, Ann. Intern. Med.
2004, 140, 1–8.
[20] J. Lindsay, D. Laurin, R. Verreault, R. Hebert, B. Helliwell,
G. B. Hill, I. McDowell, Am. J. Epidemiol. 2002, 156, 445–453.
[21] K. N. Wynne, M. Familari, J. H. Boublick, O. H. Drummer,
I. D. Rae, J. W. Funder, Clin. Exp. Pharmacol. Physiol. 1987,
14, 785–790.
[22] T. de Paulis, D. E. Schmidt, A. K. Bruchey, M. T. Kirby, M. P.
McDonald, P. Commers, D. M. Lovinger, P. R. Martin, Eur. J.
Pharmacol. 2002, 442, 215–223.
[23] Y. F. Chu, P. H. Brown, B. J. Lyle, Y. Chen, R. M. Black, C. E.
Williams, Y. C. Lin, C. W. Hsu, I. H. Cheng, J. Agric. Food
Chem. 2009, 57, 9801–9808.
[24] M. N. Clifford, S. Knight, B. Surucu, N. Kuhnert, J. Agric.
Food Chem. 2006, 54, 1957–1969.
[25] M. Sefkow, Eur. J. Org. Chem. 2001, 1137–1141.
[26] M. Sefkow, A. Kelling, U. Schilde, Eur. J. Org. Chem. 2001,
2735–2742.
[27] K. S. Raheem, N. P. Botting, G. Williamson, D. Barron, Tetra-
hedron Lett. 2011, 52, 7175–7177.
Direct Synthesis of 1,3,4-O-Tris[3,4-(dimethoxy)cinnamoyl]-1,5-γ-
quinide (3): d-(–)-quinic acid (133 mg, 0.69 mmol) was suspended
in CH2Cl2 (stored over CaCl2, 10 mL); DMAP (11.7 mg,
0.096 mmol) and Et3N (2.35 mL, 16.7 mmol) were added, and the
suspension was cooled to 0 °C. Chloride 1 (796 mg, 3.5 mmol) was
slowly added and the solution was stirred for 1 h at 0 °C and then
for 24 h at room temperature. The reaction mixture was sequen-
tially extracted with 1 m HCl (twice, 10 mL at a time), 2% NaHCO3
(12 mL), and brine (10 mL); the organic layer was dried with
Na2SO4, and the solvent was removed by vacuum evaporation. The
product was purified by flash chromatography on silica gel (glass
column 2.5ϫ35 cm, gradient elution from CH2Cl2/ethyl acetate 7:3
to 6:4 v/v); compound 3 was obtained as a yellowish powder (yield
75%).
Supporting Information (see footnote on the first page of this arti-
1
cle): H and 13C NMR spectra of all synthesized compounds.
[28] B. Neises, W. Steglich, Angew. Chem. 1978, 90, 556; Angew.
Chem. Int. Ed. Engl. 1978, 17, 522–524.
Acknowledgments
[29] U. Ragnarsson, L. Grahn, Acc. Chem. Res. 1998, 31, 494–501.
[30] R. Jaiswal, M. A. Patras, J. Eravuchira, N. Kuhnert, J. Agric.
Food Chem. 2010, 58, 8722–8737.
[31] K. Ichikawa, T. Akiyama, S. Yoshioka, H. Horikoshi,
H. Kuwano, T. Kinoshita (Sabnkyo Co.), JP 04001184,
1990.
Research activity for illycaffè s.p.a has been carried out in the
framework of “Nutrigenomica e consumo di caffè: effetti fisio-
logici, genetica del gusto e genetica della pianta” project partially
supported by the Regione Autonoma Friuli Venezia Giulia, Italy
(POR-FESR 2007–2013).
[32] K. Huang, L. Hu, F. Han, W. Xiong, H. Bai, X. Hao, M. Hu,
Y. Zhao, X. Wu, X. Li, J. Qu (Wenzhou Medical College), CN
101293834, 2008.
[1] D. I. Rees, P. D. Theaker, Proc. 8th Int. Sci. Coll. Coffee (Abid-
jan), Association Scientifique Internationale du Cafè (Paris),
1977, 79–84.
Received: November 5, 2013
Published Online: December 12, 2013
1326
www.eurjoc.org
© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2014, 1321–1326