Total Syntheses of Aporphine Alkaloids via Benzyne Chemistry: An Approach to the Formation of Aporphine Cores

Article abstract of DOI:10.1021/acs.joc.5b01634

Total syntheses of lysicamine, (±)-nuciferine, (±)-nornuciferine, (±)-zanthoxyphylline iodide, (±)-O-methylisothebaine, and (±)-trimethoxynoraporphine were accomplished by an approach that involves the formation of aporphine cores through reactions betwee

Full text of DOI:10.1021/acs.joc.5b01634

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Article
Total Syntheses of Aporphine Alkaloids via Benzyne
Chemistry: An Approach to the Formation of Aporphine Cores
Allan F. C. Rossini, Ana Carolina A. Muraca, Gleison A. Casagrande, and Cristiano Raminelli
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.5b01634 • Publication Date (Web): 16 Sep 2015
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Total Syntheses of Aporphine Alkaloids via Benzyne Chemistry: An Approach to
the Formation of Aporphine Cores
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Allan F. C. Rossini,† Ana Carolina A. Muraca,† Gleison A. Casagrande,‡ and Cristiano
Raminelli*,†
†Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de
São Paulo, Diadema, SP, Brazil
‡Instituto de Química, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS,
Brazil
ABSTRACT: Total syntheses of lysicamine, (±)-nuciferine, (±)-nornuciferine, (±)-
zanthoxyphylline iodide, (±)-O-methylisothebaine and (±)-trimethoxynoraporphine were
accomplished by approach which involves the formation of aporphine cores by reactions
between isoquinoline derivative and silylaryl triflates promoted by CsF. Unprecedented
formations of aporphine cores proceeded in good yields presumably through [4 + 2]
cycloaddition reactions followed by hydrogen migrations.
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Introduction
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Aporphine alkaloids are biosynthetic derivatives of isoquinoline alkaloids and can
be found in plants of several families.1 In terms of structural features, aporphine skeletons
are constituted by four rings (A-D), with nitrogen atom present in the B ring (Figure 1).
Aporphinoids compose a class of compounds with important pharmacological properties,
including, for example, anti-HIV activity,2 anticancer activity3 and dopaminergic
activities.4 In this sense, (R)-(-)-apomorphine hydrochloride, an example of aporphine
prototype, has currently been employed in Parkinson's disease therapy5 and erectile
dysfunction treatment6 (Figure 1).
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Figure 1. Examples of aporphine structures.
Due to the enormous pharmacological potential of aporphinoids, several synthetic
approaches for production of aporphine cores have been reported in the literature.7-10
Among all approaches for the production of aporphine alkaloids, those based on
biosynthetic routes have in common the construction of the C ring employing 1-
benzyltetrahydroisoquinoline intermediates.7-9 The classical method for representing this
strategy is the Pschorr reaction.7 In the same direction, still considering well-established
approaches, those based on benzyne chemistry, which involve reactions between 1-
methyleneisoquinolines and arenediazonium-2-carboxylates, provide aporphine
skeletons by [4 + 2] cycloaddition reactions followed by spontaneous dehydrogenations.10
In general, Pschorr reaction7 and other closely related transformations8,9 lead to
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aporphinoids in relatively low yields, require high temperatures or employ transition
metals. On the other hand, employing 1-methyleneisoquinolines and arenediazonium-2-
carboxylates, dehydroaporphines are exclusively produced in moderate yields10 (Figure
1). However, some researchers have discouraged the use of anthranilic acid-derived
arynes precursors for safety reasons.10a In addition, reduction of dehydroaporphines to
aporphines is not a well-documented transformation and the procedures of choice
disclosed in the literature involve expensive metal8d or harsh conditions.8e Nevertheless,
syntheses of aporphine alkaloids via benzyne chemistry, from a synthetic point of view,
emerge as convergent approaches.10 In this context, we conceived that reactions between
isoquinoline derivative (8) and arynes (10), formed from their silylaryl triflates (11),
under almost neutral conditions, could directly provide aporphine cores (7) instead of
dehydroaporphine skeletons, which have been accessed by arenediazonium-2-
carboxylates under acidic conditions.10
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Results and Discussion
We disclose herein advances toward direct formation of aporphine cores (7) with
application in concise syntheses of aporphine alkaloids. In this sense, our retrosynthetic
analysis for lysicamine (1), (±)-nuciferine (2), (±)-nornuciferine (3), (±)-
zanthoxyphylline
iodide
(4),
(±)-O-methylisothebaine
(5)
and
(±)-
trimethoxynoraporphine (6) is outlined in Scheme 1.
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Scheme 1. Retrosynthetic analysis for aporphine compounds.
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Lysicamine (1), (±)-nuciferine (2), (±)-nornuciferine (3), (±)-zanthoxyphylline
iodide (4), (±)-O-methylisothebaine (5) and (±)-trimethoxynoraporphine (6) are reached
by reactions between isoquinoline derivative (8) and silylaryl triflates (11), which
promote the formation of aporphine cores (7) through [4 + 2] cycloadditions followed by
hydrogen migrations (Scheme 1).
Intermediate 8 was prepared by minor modifications of well-established
reactions.10b,c,11-13 Commercially available amine (9) was treated with acetic anhydride in
pyridine to produce the corresponding amide 13 in a 97% yield.11 Amide 13 was
converted by Bischler-Napieralski reaction to the heterocyclic intermediate 14 in a 90%
yield.12 Compound 14 was allowed to react with trifluoroacetic anhydride in pyridine,
leading to the formation of intermediate 8 in an isolated yield of 70%10b,c,13 (Scheme 2).
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Scheme 2. Synthesis of intermediate 8.
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Allowing the reaction between isoquinoline derivative (8) and 1.5 equiv of benzyne
precursor (11a) in the presence of 3 equiv of CsF at room temperature for 24 hours,
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intermediate 7a was obtained in a 43% yield. Performing the same reaction at 50 C,
compound 7a was produced in an isolated yield of 50%. When the reaction was carried
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out at 80 C, intermediate 7a was obtained in a 67% yield. In these transformations,
compounds 8 and 11a were partially recovered. Besides, the corresponding
dehydroaporphine was not observed (Scheme 3).
Scheme 3. Synthesis and proposed mechanisms for the aporphine core 7a.
Reaction between isoquinoline derivative (8) and 2-(trimethysilyl)phenyl triflate
(11a) resulted in compound 7a presumably by sequence of transformations involving a
[4 + 2] cycloaddition reaction followed by a hydrogen migration (Scheme 3).
10b
Afterwards, intermediate 7a was deprotected in the presence of NaBH4
to
produce (±)-nornuciferine (3)14 in quantitative yield. Aporphine alkaloid 3 was N-
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alkylated employing formaldehyde and NaBH49a leading to (±)-nuciferine (2)15 in a 94%
yield. In order to demonstrate that oxoaporphine alkaloids can be achieved from the
intermediate 7a, compound 2 was subjected to reaction with I2 and NaOAc16 leading to
the compound 16 in a 90% yield, which was oxidized in the presence of Fremy´s sat10b
affording lysicamine (1)17 in a 69% yield (Scheme 4).
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Scheme 4. Transformations for production of aporphine alkaloids 1, 2 and 3.
(±)-Nornuciferine (3) was obtained after 6 steps with an overall yield of 41%, (±)-
nuciferine (2) was synthesized in 7 steps with overall yield of 38% and lysicamine (1)
was achieved in 9 steps with overall yield of 24%.
Intermediate 11b was obtained employing route outlined in Scheme 5.18 3-
Methoxyphenol (12) was allowed to react with hexamethyldisilazane (HMDS) to give the
protected phenol 17 in quantitative yield. Compound 17 was treated with lithium
diisopropylamide (LDA) and trimethylsilyl chloride (TMSCl) to produce the disilylated
intermediate 18 in an isolated yield of 81%. Intermediate 18 had its hydroxyl group
deprotected in the presence of n-BuLi and the resulting phenolate ion was trapped with
triflic anhydride (Tf2O), leading to the intermediate 11b in an 80% yield (Scheme 5).18
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Scheme 5. Synthesis of intermediate 11b.
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Allowing the reaction between isoquinoline derivative (8) and 1.5 equiv of silylaryl
triflate (11b) in the presence of 3 equiv of CsF at room temperature for 24 hours,
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intermediate 7b was obtained in a 40% yield. Performing the same reaction at 50 C,
compound 7b was produced in an isolated yield of 58%. When the reaction was carried
out at 80 oC, no improvement in yield was observed and the intermediate 7b was obtained
in a 55% yield. In these experiments, compounds 8 and 11b were partially recovered and
the corresponding dehydroaporphine was not observed (Scheme 6).
Scheme 6. Synthesis and proposed mechanisms for the aporphine core 7b.
Reaction between isoquinoline derivative (8) and silylaryl triflate (11b) produced
compound 7b as a single regio- and diastereoisomer,19 constituted by P,S and M,R
enantiomers, presumably by sequence of transformations involving a polar [4 + 2]
cycloaddition reaction followed by a hydrogen migration (Scheme 6).
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10b
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Afterwards, intermediate 7b was deprotected in the presence of NaBH4
to
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produce (±)-trimethoxynoraporphine (6)20 in quantitative yield. In this case, aporphine
alkaloid 6 was N-alkylated and N,N-dialkyated employing MeI and K2CO321 to produce
(±)-O-methylisothebaine (5)22 and (±)-zanthoxyphylline iodide (4)23 in yields of 72% and
82%, respectively (Scheme 7).
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Scheme 7. Transformations for production of aporphinoids 4, 5 and 6.
(±)-Trimethoxynoraporphine (6) was obtained after 6 steps with an overall yield of
35%. (±)-O-Methylisothebaine (5) and (±)-zanthoxyphylline iodide (4) were both
synthesized in 7 steps with overall yields of 26% and 29%, respectively.
The structures of compounds 2-6, 8, 11b, 13, 14 and 16-18 were assigned according
to their LRMS, IR, 1H, and 13C NMR spectra. The structure of compound 1 was assigned
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according to its IR, H, and C NMR spectra. DEPT, COSY, and HSQC NMR spectra
were obtained to confirm the structure of compound 4. HRMS were obtained for
compounds 1, 4 and 6. The structure of compound 7a was assigned according to its
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LRMS, HRMS, IR, H, C, DEPT, COSY, and HSQC NMR spectra. The structure of
compound 7b was assigned according to its LRMS, HRMS, IR, 1H, 13C, DEPT, COSY,
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HSQC, and HMBC NMR spectra and unambiguously confirmed by single-crystal X-ray
diffraction (Supporting Information).
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In summary, we have developed concise routes toward the syntheses of lysicamine
(1), (±)-nuciferine (2), (±)-nornuciferine (3), (±)-zanthoxyphylline iodide (4), (±)-O-
methylisothebaine (5) and (±)-trimethoxynoraporphine (6). Our approach involves the
formation of aporphine cores (7) by reactions between isoquinoline derivative (8) and
silylaryl triflates (11) promoted by CsF. The formation of aporphine cores (7) proceeded
in good yields presumably through [4 + 2] cycloaddition reactions followed by hydrogen
migrations. The chemistry disclosed represents an advance for the synthesis of aporphine
alkaloids, providing aporphine cores under mild reaction conditions, and should find
application in the preparation of other aporphinoids.
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EXPERIMENTAL SECTION
1H NMR spectra were recorded on spectrometers operating at 500 MHz or 300 MHz. 13C
NMR spectra were recorded on spectrometers operating at 125 MHz or 75 MHz. 1H NMR
spectra were taken in deuterated solvents and the chemical shifts were given in ppm with
respect to tetramethylsilane (TMS) used as internal standard. 13C NMR spectra were taken
in deuterated solvents and the chemical shifts were given in ppm with respect to
deuterated solvents used as references. Infrared spectra were obtained using attenuated
total reflectance (ATR) or KBr pellets in 4000-400 cm-1 region. Mass spectra were carried
out employing a gas chromatograph connected to a mass spectrometer using electron
impact ionization at 70 eV or employing a liquid chromatograph connected to a mass
spectrometer using electrospray ionization source. High resolution mass spectra were
obtained using a time-of-flight mass spectrometer. Melting point values are uncorrected.
Column chromatography separations were carried out using 70-230 mesh silica gel.
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Preparative thin layer chromatography separations were carried out using silica gel matrix
with inorganic binder and fluorescent indicator. Commercially obtained reagents were
employed without further purification. High purity cesium fluoride (99.99%) was used in
the experiments. THF and diethyl ether were distilled from sodium/benzophenone under
nitrogen atmosphere before use.24 n-Butyllithium (n-BuLi) was titrated against sec-
butanol using 1,10-phenanthroline as indicator under nitrogen atmosphere.25 Lithium
diisopropylamide (LDA) was generated following typical procedure before use.26
Acetonitrile was distilled from calcium hydride under nitrogen atmosphere prior to use.24
Solvents were treated when necessary according to the literature.24
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N-(3,4-Dimethoxyphenethyl)acetamide (13).11 To a round-bottomed flask were added
2-(3,4-dimethoxyphenyl)ethanamine (9) (10 mmol, 1.81 g, 1.70 mL), dry pyridine (11
mmol, 870 mg, 0.90 mL) and acetic anhydride (11,5 mmol, 1.17 g, 1.10 mL). The round-
bottomed flask was capped with a rubber septum and the reaction mixture was maintained
under stirring at 90 oC for 2 h. After that, the reaction was poured into a beaker containing
crushed ice (50 g) and concentrated HCl (15 mL) was added. The resulting mixture was
stirred with a glass rod for 5 min. Afterwards, a saturated aqueous solution of NaHCO3
(50 mL) was added to the mixture, which was extracted with ethyl acetate (3 x 50 mL).
The organic phase was washed with a saturated aqueous solution of CuSO4 (50 mL) and
dried over MgSO4. After filtration, the solvent was evaporated under reduced pressure,
affording the desired product 13. Rf = 0.81 (eluent: methanol); yield: 2.16 g (97%); off-
white solid; m.p. 99-100 oC (lit.27 m.p. 99-100 oC); 1H NMR (300 MHz, CDCl3): δ 6.81
(dd, J = 5.6, 3.0 Hz 1H), 6.73 (dd, J = 5.8, 2.0 Hz, 2H), 5.96 (s, 1H), 3.86 (s, 3H), 3.85
13
(s, 3H), 3.48 (q, J = 6.7 Hz, 2H), 2.76 (t, J = 7.1 Hz, 2H), 1.94 (s, 3H); C NMR (75
MHz, CDCl3): δ 170.0, 148.8, 147.4, 131.2, 120.4, 111.7, 111.2, 55.7, 55.6, 40.6, 35.0,
23.0; IR (KBr, cm-1) 3251.9, 3080.3, 2972.3, 2927.9, 1633.7, 1608.6, 1566.2, 1516.0,
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1417.6, 1377.1, 1261.4, 1035.7; GC/MS (m/z, %): 223 (7.3), 180 (0.3), 164 (100.0), 151
(41.6), 121 (4.1), 108 (3.4), 107 (7.9).
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Procedure for preparation of intermediate salt and compound 14.12 To a round-
bottomed flask were added N-(3,4-dimethoxyphenethyl)acetamide (13) (4 mmol, 892
mg) and toluene (4.5 mL). The round-bottomed flask was equipped with a reflux
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condenser and capped with a rubber septum. The mixture was heated at 40 C under
stirring and anhydrous conditions. After that, POCl3 (9.6 mmol, 1.47 g, 0.88 mL) was
added dropwise using syringe and needle. The rubber septum was substituted by a glass
cap and the reaction mixture was refluxed for 2 h. Then, the mixture was cooled with an
ice bath for 4 h. The solvent was evaporated under reduced pressure, affording an
intermediate salt. Afterwards, the intermediate salt was dissolved in water (10 mL) and a
40% (w/v) aqueous solution of NaOH (10 mL) was added to the mixture, which was
maintained under stirring for 10 min. The mixture was extracted with CHCl3 (3 x 20 mL).
The organic phase was washed with distilled water (10 mL) and dried over MgSO4. After
filtration, the solvent was evaporated under reduced pressure, affording the desired
product 14.
6,7-Dimethoxy-1-methyl-3,4-dihydroisoquinolinium
phosphorodichloridate
(intermediate salt). Rf = 0.13 (eluent: methanol); yield: 1.36 g (quantitative); yellowish
solid; m.p. 146-149 oC (lit.12 m.p. 148-152 oC); 1H NMR (300 MHz, D2O): δ 7.14 (s, 1H),
6.87 (s, 1H), 3.78 (s, 3H), 3.73 (s, 3H), 3.71 (t, J = 7.5 Hz, 2H), 2.94 (t, J = 8.1 Hz, 2H),
2.60 (s, 3H); 13C NMR (75 MHz, D2O): δ 175.3, 155.5, 147.4, 134.0, 117.6, 111.7, 110.8,
56.2, 55.9, 40.8, 24.3, 19.6; IR (KBr, cm-1) 3431.3, 3205.6, 3089.6, 3055.2, 2972.3,
2927.9, 2891.3, 1664.5, 1602.8, 1566.2, 1516.0, 1427.3, 1346.3, 1217.0, 1165.0, 1068.5,
1012.6; LC/MS (m/z, %) ESI-(+) 206.3 (100.0), 190.2 (60.2), 174.4 (16.2), 162.2 (8.1),
144.1 (16.2), 132.3 (32.4) and ESI-(-) 137.1 (18.1), 135.0 (63.3), 133.0 (100.0).
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6,7-Dimethoxy-1-methyl-3,4-dihydroisoquinoline (14). Rf = 0.38 (eluent:
methanol); yield: 738 mg (90%); brownish solid; m.p. 102-103 °C (lit.28 m.p. 100-102
oC); 1H NMR (300 MHz, CDCl3): δ 6.99 (s, 1H), 6.69 (s, 1H), 3.92 (s, 3H), 3.91 (s, 3H),
3.63 (tq, J = 7.6, 1.4 Hz, 2H), 2.64 (t, J = 7.6 Hz, 2H), 2.37 (t, J = 1.4 Hz, 3H); 13C NMR
(75 MHz, CDCl3): δ 163.6, 150.8, 147.3, 131.0, 122.4, 110.1, 108.9, 56.1, 55.9, 46.9,
25.6, 23.3; IR (KBr, cm-1) 2993.5, 2962.6, 2922.1, 1602.8, 1514.1, 1408.4, 1350.1,
1213.2, 1060.8; GC/MS (m/z, %): 205 (100.0), 190 (57.9) 174 (21.5), 160 (21.4), 147
(12.8), 132 (4.3).
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1-(6,7-Dimethoxy-1-methylene-3,4-dihydroisoquinolin-2(1H)-yl)-2,2,2-
trifluoroethanone (8).10b,c,13 To a round-bottomed flask capped with a rubber septum
were added 6,7-dimethoxy-1-methyl-3,4-dihydroisoquinoline (14) (1 mmol, 205 mg) and
a solution of dry pyridine (1.25 mmol, 98.9 mg) in CH2Cl2 (3.1 mL). The mixture was
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cooled to -50 C under stirring and nitrogen atmosphere. A solution of trifluoroacetic
anhydride (1.25 mmol, 263 mg) in CH2Cl2 (0.75 mL) was added dropwise using syringe
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and needle. The reaction mixture was maintained at -50 C under stirring and nitrogen
atmosphere for 3 h. Afterwards, the reaction was diluted with CH2Cl2 (10 mL) and
washed with distilled water (10 mL). The organic phase was dried over MgSO4. After
filtration, the solvent was evaporated under reduced pressure. The residue was purified
by column chromatography on silica gel using CH2Cl2 as eluent, affording the desired
product 8. Rf = 0.60 (eluent: dichloromethane); yield: 211 mg (70%); off-white solid;
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m.p. 83-85 C (lit.13 m.p. 80 C); H NMR (300 MHz, CDCl3): δ 7.03 (s, 1H), 6.59 (s,
1H), 5.62 (s, 1H), 5.24 (s, 1H), 4.04 (s, 2H), 3.91 (s, 3H), 3.88 (s, 3H), 2.94 (t, J = 6.0 Hz,
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2H); C NMR (75 MHz, CDCl3): δ 155.6 (q, J = 35.8 Hz), 150.1, 148.1, 126.3, 123.4,
116.5 (q, J = 286.5 Hz), 111.1, 106.8, 106.6, 106.5, 56.0, 55.9, 44.6, 28.4; IR (KBr, cm-
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1) 3014.7, 2962.6, 2931.8, 1697.3, 1608.6, 1512.1, 1438.9, 1338.6, 1273.0, 1132.2,
1033.8; GC/MS (m/z, %): 301 (82.0), 286 (5.7), 270 (3.5), 232 (100.0), 204 (59.1).
2,2,2-Trifluoro-1-(1,2-dimethoxy-6a,7-dihydro-4H-dibenzo[de,g]quinolin-6(5H)-
yl)ethanone (7a). To a vial (20 mL) were added the heterocyclic compound 8 (0.3 mmol,
90.3 mg), the silylaryl triflate 11a (0.45 mmol, 134 mg), acetonitrile (5 mL) and CsF (0.9
mmol, 137 mg). The vial was sealed using a cap and the mixture was stirred at 80 ºC for
24 h. Afterwards, brine (10 mL) was added to the mixture, which was extracted with ethyl
acetate (3 x 10 mL). The organic phase was dried over MgSO4. After filtration, the solvent
was evaporated under reduced pressure. The residue was purified by preparative thin layer
chromatography on silica gel using CH2Cl2 as eluent affording the desired product 7a. Rf
= 0.68 (eluent: dichlorometane); yield: 75.8 mg (67%); off-white solid; m.p. 156-157 °C;
1H NMR (300 MHz, CDCl3): δ 8.45 (d, J = 7.8 Hz, 1H), 7.37-7.26 (m, 3H), 6.68 (s, 1H),
5.03 (dd, J = 13.7, 4.0 Hz, 1H), 4.25-4.20 (m, 1H), 3.90 (s, 3H), 3.68 (s, 3H), 3.36 (td, J
= 12.9, 2.3 Hz, 1H), 2.74-3.09 (m, 4H); 13C NMR (75 MHz, CDCl3): δ 155.8 (q, J = 35.3
Hz), 152.4, 146.1, 135.7, 131.3, 128.6, 128.5, 128.3, 128.0, 127.7, 127.3, 124.5, 116.3 (q,
J = 285.0 Hz), 111.2, 60.0, 55.9, 52.2, 41.1, 33.5, 30.3; IR (KBr, cm-1) 2933.7, 2617.4,
1678.1, 1608.6, 1593.2, 1423.5, 1373.3, 1259.5, 1197.8, 1141.9, 927.8, 655.8; GC/MS
(m/z, %): 377 (49.0), 308 (5.5), 281 (4.3), 251 (100.0), 165 (28.6); HRMS calcd for
[C20H18F3NO3 + H]+ 378.1312, found 378.1311.
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1,2-Dimethoxy-5,6,6a,7-tetrahydro-4H-dibenzo[de,g]quinoline (3).10b To a round-
bottomed flask capped with a rubber septum were added the compound 7a (0.18 mmol,
67.9 mg) and ethanol (10 mL). The resulting suspension was maintained under stirring
until complete solubilization of the compound 7a. After that, NaBH4 (1.8 mmol, 68.1 mg)
was added and the reaction mixture was maintained at room temperature under stirring
and nitrogen atmosphere for 10 min. Afterwards, the ethanol was evaporated under
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reduced pressure and brine (10 mL) was added to the residue, which was extracted with
CH2Cl2 (3 x 10 mL). The organic phase was dried over MgSO4. After filtration, the
solvent was evaporated under reduced pressure, affording the alkaloid 3.14 Rf = 0.26
(eluent: metanol); yield: 50.4 mg (quantitative); off-white solid; m.p. 124-125 °C (lit.14
m.p. 128-129 °C); 1H NMR (300 MHz, CDCl3): δ 8.30 (d, J = 7.8 Hz, 1H), 7.19-7.11 (m,
3H), 6.54 (s, 1H), 3.77 (s, 3H), 3.70 (dd, J = 13.4, 4.5 Hz, 1H), 3.57 (s, 3H), 3.23-3.26
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(m, 1H), 2.95-2.83 (m, 2H), 2.76-2.56 (m, 3H); C NMR (75 MHz, CDCl3): δ 152.2,
145.2, 136.2, 132.2, 128.9, 128.9, 128.4, 127.8, 127.4, 127.0, 126.6, 111.9, 60.3, 55.9,
53.6, 43.2, 37.5, 29.2; IR (KBr, cm-1) 3324.5, 2928.1, 2835.5, 2316.6, 1593.3, 1451.5,
1423.5, 1251.9, 1248.0, 1034.8, 754.2; GC/MS (m/z, %): 281 (49.3), 280 (100.0), 264
(17.7), 250 (22.2), 236 (18.0), 221 (16.2), 165 (16.0).
1,2-Trimethoxy-6-methyl-5,6,6a,7-tetrahydro-4H-dibenzo[de,g]quinolone (2).9a To a
round-bottomed flask was added nornuciferine (3) (0.14 mmol, 39.3 mg), methanol (3.8
mL) and a 37% (w/v) aqueous solution of CH2O (1.1 mL). The reaction mixture was
stirred at room temperature for 30 min. Then, NaBH4 (2.8 mmol, 106 mg) was added and
the mixture was stirred at room temperature for 1 h. Afterwards, brine (10 mL) was added
to the mixture, which was extracted with ethyl acetate (3 x 10 mL). The organic phase
was dried over MgSO4. After filtration, the solvent was evaporated under reduced
pressure. The residue was purified by preparative thin layer chromatography on silica gel
using methanol as eluent, affording the alkaloid 2.15 Rf = 0.60 (eluent: methanol); yield:
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38.7 mg (94%); yellowish solid; m.p. 168-169 °C (lit.15 m.p. 165.5 °C); H NMR (300
MHz, CDCl3): δ 8.30 (d, J = 7.8 Hz, 1H), 7.25-7.16 (m, 3H), 6.56 (s, 1H), 3.81 (s, 3H),
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3.57 (s, 3H), 3.12-2.98 (m, 4H), 2.50 (s, 1H), 2.42-2.66 (m, 3H); C NMR (75 MHz,
CDCl3): δ 151.9, 144.9, 136.1, 131.9, 128.4, 128.2, 127.8, 127.3, 127.2, 127.0, 126.7,
110.9, 62.1, 60.2, 55.7, 53.0, 43.7, 34.7, 28.8; IR (KBr, cm-1) 2950.1, 2930.8, 2834.4,
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1594.2, 1451.4, 1321.2, 1301.0, 1249.9, 1035.8; GC/MS (m/z, %): 295 (32.0), 293
(100.0), 278 (45.6), 264 (16.9), 250 (18.3), 235 (34.9).
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1,2,11-Trimethoxy-6-methyl-5,6,6a,7-tetrahydro-4H-dibenzo[de,g]quinolone (16).16
A solution of iodine (0.12 mmol, 30.5 mg) in dioxane (2.9 mL) was added dropwise to a
refluxing suspension of nuciferine (2) (0.12 mmol, 36.3 mg) and anhydrous NaOAc (0.48
mmol, 38.7 mg) in dioxane (2.1 mL). The reaction mixture was refluxed under stirring
and anhydrous conditions for 2 h. Afterwards, the solvent was evaporated under reduced
pressure. To the residue was added a saturated aqueous solution of Na2S2O3 (10 mL) and
the mixture was extracted with CHCl3 (3 x 10 mL). The organic phase was dried over
MgSO4. After filtration, the solvent was evaporated under reduced pressure. The residue
was purified by preparative thin layer chromatography on silica gel using methanol/ethyl
acetate (1:1) as eluent, affording the desired product 16. Rf = 0.68 (eluent: methanol);
yield: 31.7 mg (90%); brownish solid; m.p. 128-130 °C (lit.16 m.p. 130-131 °C); 1H NMR
(300 MHz, CDCl3): δ 9.38 (d, J = 8.4 Hz, 1H), 7.56 (dd, J = 8.0, 1.1 Hz, 1H), 7.37 (tdap,
J = 7.4, 1.0 Hz, 1H), 7.25 (tdap, J = 7.7, 1.5 Hz, 1H), 6.93 (s, 1H), 6.55 (s, 1H), 3.92 (s,
3H), 3.81 (s, 3H), 3.28 (tap, J = 6.0 Hz, 2H), 3.18 (tap, J = 6.0 Hz, 2H), 3.00 (s, 3H); 13C
NMR (75 MHz, CDCl3): δ 151.1, 145.8, 134.6, 129.0, 127.7, 126.9, 126.5, 125.8, 124.8,
123.0, 119.0, 111.5, 59.7, 56.4, 50.3, 40.7, 30.7; IR (KBr, cm-1) 2926.0, 2880.7, 1559.5,
1448.5, 1423.5, 1332.8, 1199.7, 1117.8, 1003.0, 826.5; GC/MS (m/z, %): 293 (100.0),
278 (43.8), 263 (15.5), 250 (21.8), 235 (47.0).
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1,2-Dimethoxy-7H-dibenzo[de,g]quinolin-7-one (1).10b To
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solution of
dehydronuciferine (16) (0.072 mmol, 21.2 mg) in methanol (10 mL) was added the
Fremy's salt ((KSO3)2NO) (0.72 mmol, 193 mg) in a 4% (w/v) aqueous solution of
Na2CO3 (5 mL). The reaction mixture was maintained under stirring at room temperature
for 24 h. Afterwards, brine (10 mL) was added to the mixture, which was extracted with
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ethyl acetate (3 x 10 mL). The organic phase was dried over MgSO4. After filtration, the
solvent was evaporated under reduced pressure. The residue was purified by preparative
thin layer chromatography on silica gel using methanol as eluent, affording the alkaloid
1.17 Rf = 0.68 (eluent: methanol); yield: 14.4 mg (69%); yellowish solid; m.p. 204-206
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°C (decomp.) ((lit.17 m.p. 210-211 °C (decomp.)); H NMR (300 MHz, CDCl3): δ 9.18
(d, J = 8.3 Hz, 1H), 8.91 (d, J = 5.2 Hz, 1H), 8.60 (d, J = 7.8 Hz, 1H), 7.80 (d, J = 5.1 Hz,
1H), 7.76 (d, J = 7.32 Hz, 1H), 7.58 (tap, J = 6.0 Hz, 1H), 7.23 (s, 1H), 4.11 (s, 3H), 4.02
13
(s, 3H); C NMR (75 MHz, CDCl3): δ 182.7, 156.9, 152.1, 145.3, 144.9, 135.5, 134.4,
134.3, 132.1, 128.9, 128.8, 128.5, 123.6, 122.2, 119.80, 106.5, 56.2, 50.8; IR (KBr, cm-
1) 3309.9, 2922.2, 2848.9, 1670.4, 1483.3, 1305.8, 1261.5, 1043.5, 869.9, 746.5; HRMS
calcd for [C18H13NO3 + H]+ 292.0968, found 292.0973.
(3-Methoxyphenoxy)trimethylsilane (17).18 To a round-bottomed flask capped with a
rubber septum were added 3-methoxyphenol (12) (10 mmol, 1.24 g, 1.4 mL) and
hexamethyldisilazane (HMDS) (15 mmol, 2.42 g, 3.2 mL). The reaction mixture was
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maintained at 80 C under stirring and nitrogen atmosphere for 3 h. The volatile
substances were removed under reduced pressure, affording the desired product 17. Rf =
0.39 (eluent: hexane/dichlorometane (3:1)); yield: 1.96 g (quantitative); yellowish oil;18
1H NMR (300 MHz, CDCl3): δ 7.12 (t, J = 8.1 Hz, 1H), 6.53 (ddd, J = 8.3, 2.4, 0.8 Hz,
1H), 6.45 (ddd, J = 8.0, 2.2, 0.8 Hz, 1H), 6.41 (t, J = 2.3 Hz, 1H), 3.76 (s, 3H), 0.26 (s,
9H); 13C NMR (75 MHz, CDCl3): δ 160.7, 156.3, 129.7, 112.5, 107.0, 106.2, 55.2, 0.2;
IR (ATR, cm-1) 3066.8, 3001.2, 2958.8, 2900.9, 2835.3, 1597.0, 1489.0, 1450.4, 1253.7,
1041.5, 840.9; GC/MS (m/z, %): 196 (54.6), 181 (100.0), 151 (15.5), 135 (2.1), 121 (4.7),
107 (2.4), 89 (12.2).
(3-Methoxy-2-(trimethylsilyl)phenoxy)trimethylsilane (18).18 To a round-bottomed
flask capped with a rubber septum were added (3-methoxyphenoxy)trimethylsilane (17)
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(5 mmol, 981 mg) and THF (7.5 mL). The mixture was cooled to -78 C under stirring
and nitrogen atmosphere. After that, LDA (5.5 mmol, 10 mL of a 0.55 mol.L-1 solution
in THF) was added dropwise using syringe and needle. The reaction mixture was heated
to room temperature and maintained at room temperature for 90 min. Then, the mixture
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was cooled to -78 C under stirring and nitrogen atmosphere. After that, trimethylsilyl
chloride (TMSCl) (6 mmol, 648 mg, 0.76 mL) was added. The reaction mixture was
heated to room temperature and maintained at room temperature for 18 h. Afterwards, a
saturated aqueous solution of NH4Cl (50 mL) was added to the reaction, which was
extracted with ethyl acetate (3 x 50 mL). The organic phase was dried over MgSO4. After
filtration, the solvent was evaporated under reduced pressure. The residue was purified
by column chromatography on silica gel using hexane/CH2Cl2 (3:1) as eluent, affording
the desired product 18. Rf = 0.69 (eluent: hexane/dichlorometane (3:1)); yield: 1.09 g
(81%); colorless oil;18 1H NMR (300 MHz, CDCl3): δ 7.15 (t, J = 8.2 Hz, 1H), 6.45 (d, J
= 8.2 Hz, 1H), 6.41 (d, J = 8.1 Hz, 1H), 3.73 (s, 3H), 0.30 (s, 9H), 0.28 (s, 9H); 13C NMR
(75 MHz, CDCl3): δ 165.7, 161.2, 130.8, 116.7, 110.8, 103.2, 55.1, 1.5, 0.7; IR (ATR,
cm-1) 3082.2, 3051.3, 2954.9, 2897.0, 2831.5, 1570.1, 1431.1, 1234.4, 1087.8, 833.2;
GC/MS (m/z, %): 268 (40.9), 253 (100.0), 238 (7.8), 237 (16.5), 163 (6.2), 133 (11.7),
105 (16.9), 89 (7.0), 73 (38.8).
3-Methoxy-2-(trimethylsilyl)phenyl trifluoromethanesulfonate (11b).18 To a round-
bottomed flask capped with a rubber septum were added (3-methoxy-2-
(trimethylsilyl)phenoxy)trimethylsilane (18) (1 mmol, 268 mg) and diethyl ether (10 mL).
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The mixture was cooled to 0 C under stirring and nitrogen atmosphere. After that, n-
BuLi (1.1 mmol, 0.75 mL of a 1.47 mol.L-1 solution in hexane) was added dropwise using
syringe and needle. The reaction mixture was heated to room temperature and maintained
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at room temperature for 4 h. Then, the mixture was cooled to 0 C under stirring and
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anhydrous conditions. After that, triflic anhydride (2 mmol, 564 mg, 0.37 mL) was added.
The reaction mixture was heated to room temperature and maintained at room
temperature for 18 h. Afterwards, a 10% (w/v) aqueous solution of NaHCO3 (10 mL) was
added to the reaction, which was extracted with diethyl ether (3 x 10 mL). The organic
phase was dried over MgSO4. After filtration, the solvent was evaporated under reduced
pressure. The residue was purified by column chromatography on silica gel using
hexane/CH2Cl2 (2:1) as eluent, affording the desired product 11b. Rf = 0.59 (eluent:
hexane/dichlorometane (2:1)); yield: 262 mg (80%); colorless oil;18 1H NMR (300 MHz,
CDCl3): δ 7.36 (t, J = 8.3 Hz, 1H), 6.94 (d, J = 8.4 Hz, 1H), 6.83 (d, J = 8.2 Hz, 1H), 3.82
(s, 3H), 0.36 (s, 9H); 13C NMR (75 MHz, CDCl3): δ 165.5, 154.7, 131.6, 120.8, 118.6 (q,
J = 320.7 Hz), 112.7 (q, J = 1.5 Hz), 109.5, 55.6, 0.75; IR (ATR, cm-1) 2956.8, 2900.9,
2839.2, 1597.0, 1458.1, 1415.7, 1284.5, 1247.9, 1161.1, 1138.0, 1047.3, 932.9, 825.5;
GC/MS (m/z, %): 328 (1.1), 313 (91.7), 180 (100.0), 165 (17.2), 105 (21.2).
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2,2,2-Trifluoro-1-(1,2,11-trimethoxy-6a,7-dihydro-4H-dibenzo[de,g]quinolin-
6(5H)-yl)ethanone (7b). To a vial (20 mL) were added the heterocyclic compound 8 (0.3
mmol, 90.3 mg), the silylaryl triflate 11b (0.45 mmol, 148 mg), acetonitrile (5 mL) and
CsF (0.9 mmol, 137 mg). The vial was sealed using a cap and the mixture was stirred at
50 ºC for 24 h. Afterwards, brine (10 mL) was added to the mixture, which was extracted
with ethyl acetate (3 x 10 mL). The organic phase was dried over MgSO4. After filtration,
the solvent was evaporated under reduced pressure. The residue was purified by
preparative thin layer chromatography on silica gel using CH2Cl2 as eluent. The solid
obtained after chromatography was washed with cold methanol, affording compound 7b.
Rf = 0.55 (eluent: dichloromethane); yield: 70.8 mg (58%); off-white solid; m.p. 218-219
°C; 1H NMR (500 MHz, CDCl3): δ 7.26 (t, J = 7.9 Hz, 1H), 6.94 (d, J = 8.4 Hz, 1H), 6.91
(d, J = 7.4 Hz, 1H), 6.67 (s, 1H), 4.89 (dd, J = 13.0, 3.3 Hz, 1H), 4.22 (d, J = 13.3 Hz,
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1H), 3.90 (s, 3H), 3.90 (s, 3H), 3.64 (s, 3H), 3.30 (td, J = 13.0, 2.3 Hz, 1H), 2.97-2.91 (m,
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2H), 2.77-2.69 (m, 2H); C NMR (125 MHz, CDCl3): δ 157.1, 156.0 (q, J = 35.6 Hz),
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152.2, 146.3, 138.3, 128.9, 126.7, 125.5, 125.2, 120.3, 116.3 (q, J = 288.3 Hz), 111.1,
110.4, 77.2, 60.7, 55.9, 55.7, 52.4, 41.4, 34.6, 29.9; IR (KBr, cm-1) 2995.5, 2956.9,
2835.4, 1691.6, 1606.7, 1465.9, 1433.1, 1365.6, 1271.1, 1227.0, 1172.7, 1141.9, 1045.4,
929.7, 817.8, 841.0; GC/MS (m/z, %): 407 (91.8), 392 (2.4), 361 (1.6), 338 (4.9), 307
(3.7), 281 (100.0), 279 (5.3), 191 (8.3), 126 (4.6); HRMS calcd for [C21H20F3NO4 + H]+
408.1417, found 408.1415.
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1,2,11-Trimethoxy-5,6,6a,7-tetrahydro-4H-dibenzo[de,g]quinoline (6).10b To
a
round-bottomed flask capped with a rubber septum were added the compound 7b (0.1
mmol, 40.8 mg) and THF (5 mL). The resulting suspension was maintained under stirring
until complete solubilization of the compound 7b. After that, ethanol (5 mL) and NaBH4
(0.3 mmol, 11.4 mg) were added and the reaction mixture was maintained at room
temperature under stirring and nitrogen atmosphere for 15 min. Afterwards, the mixture
of solvents was evaporated under reduced pressure and brine (10 mL) was added to the
residue, which was extracted with CH2Cl2 (3 x 10 mL). The organic phase was dried over
MgSO4. After filtration, the solvent was evaporated under reduced pressure, affording the
alkaloid 6.20 Rf = 0.25 (eluent: metanol); yield: 31.1 mg (quantitative); off-white solid;
m.p. 162-163 °C; 1H NMR (300 MHz, CDCl3): δ 7.22 (t, J = 7.9 Hz, 1H), 6.91 (d, J = 8.2
Hz, 1H), 6.88 (d, J = 7.2 Hz, 1H), 6.66 (s, 1H), 4.01 (s, 1H), 3.87 (s, 6H), 3.74 (dd, J =
12.4, 1.7 Hz, 1H), 3.61 (s, 3H), 3.45-3.37 (m, 1H), 3.10-2.97 (m, 2H), 2.86 (dd, J = 13.7,
3.7 Hz, 1H), 2.79-2.54 (m, 2H); 13C NMR (75 MHz, CDCl3): δ 156.8, 152.0, 145.7, 138.2,
129.0, 128.3, 127.0, 124.1, 121.1, 119.7, 111.5, 110.1, 60.8, 55.9, 55.6, 53.9, 42.6, 37.7,
28.0; IR (KBr, cm-1) 3431.4, 2991.6, 2935.7, 2831.5, 1591.3, 1462.0, 1423.5, 1269.2,
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1248.0, 1037.7; GC/MS (m/z, %): 311 (51.9), 310 (36.3), 296 (73.7), 280 (100.0), 265
(32.6); HRMS calcd for [C19H21NO3 + H]+ 312.1594, found 312.1610.
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1,2,11-Trimethoxy-6-methyl-5,6,6a,7-tetrahydro-4H-dibenzo[de,g]quinoline (5).21
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To
a
round-bottomed flask capped with
a
rubber septum were added
trimethoxynoraporphine (6) (0.1 mmol, 31.1 mg), K2CO3 (0.2 mmol, 27.6 mg), acetone
(4 mL) and methyl iodide (0.15 mmol, 21.3 mg, 9.4 µL). The reaction mixture was
maintained at room temperature under stirring and nitrogen atmosphere for 6 h.
Afterwards, brine (10 mL) was added to the mixture, which was extracted with ethyl
acetate (3 x 10 mL). The organic phase was dried over MgSO4. After filtration, the solvent
was evaporated under reduced pressure. The residue was purified by preparative thin layer
chromatography on silica gel using methanol as eluent, affording the alkaloid 5.22 Rf =
1
0.54 (eluent: methanol); yield: 23.4 mg (72%); yellowish solid; m.p. 147-149 °C; H
NMR (300 MHz, CDCl3): δ 7.23 (t, J = 7.7 Hz, 1H), 6.91 (d, J = 8.0 Hz, 1H), 6.89 (d, J
= 7.0 Hz, 1H), 6.67 (s, 1H), 3.88 (s, 6H), 3.76 (dd, J = 13.5, 3.0 Hz, 1H), 3.61 (s, 3H),
3.50-3.40 (m, 1H), 3.10-2.95 (m, 2H), 2.89 (dd, J = 13.6, 3.5 Hz, 1H), 2.80-2.60 (m, 1H),
13
1.25 (s, 3H); C NMR (75 MHz, CDCl3): δ 156.8, 152.1, 145.7, 138.1, 128.8, 128.4,
127.0, 124.1, 121.1, 119.7, 111.5, 110.2, 60.8, 55.9, 55.7, 54.0, 42.7, 37.7, 29.7, 28.0; IR
(KBr, cm-1) 2935.7, 2831.5, 1591.3, 1458.2, 1423.5, 1269.2, 1247.9, 1037.7; GC/MS
(m/z, %): 325 (43.3), 324 (20.8), 310 (77.7), 294 (100.0), 279 (36.3).
1,2,11-Trimethoxy-6,6-dimethyl-5,6,6a,7-tetrahydro-4H-dibenzo[de,g]quinolin-6-
ium iodide (4).21 To a round-bottomed flask were added trimethoxynoraporphine (6) (0.1
mmol, 31.1 mg), K2CO3 (200 mg), acetone (8 mL) and methyl iodide (2 mL). The round-
bottomed flask was equipped with a reflux condenser and capped with a glass cap. The
mixture was maintained under reflux, stirring and nitrogen atmosphere for 36 h.
Afterwards, the mixture was evaporated under reduced pressure. The material obtained
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was washed with distilled water (3 x 3 mL) and separated by centrifugation (4000 rpm
5
6
for 10 min), affording the desired product 4.23 Yield: 38.2 mg (82%); off-white solid; m.p.
7
8
9
o
o
1
248-250 C (lit.23 m.p. 256 C); H NMR (300 MHz, DMSO-d6): δ 7.33 (t, J = 7.9 Hz,
1H), 7.07 (d, J = 8.3 Hz, 1H), 7.00 (d, J = 7.3 Hz, 1H), 6.96 (s, 1H), 4.48 (dd, J = 13.3,
1.9 Hz, 1H), 3.85 (s, 3H), 3.83-3.77 (m, 4H), 3.72-3.64 (m, 4H), 3.39-3.36 (m, 4H), 3.23
(ddd, J = 17.1, 12.2, 5.2 Hz, 1H), 3.00 (dd, J = 18.3, 4.0 Hz, 1H), 2.90 (s, 3H), 2.73 (t, J
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13
= 13.3 Hz, 1H); C NMR (75 MHz, DMSO-d6): δ 156.8, 153.1, 146.4, 135.4, 129.6,
124.1, 123.4, 121.8, 120.2, 120.1, 111.5, 68.4, 60.9, 60.6, 56.3, 56.0, 53.6, 43.4, 30.5,
23.4; IR (KBr, cm-1) 2999.3, 2926.0, 2833.4, 1593.2, 1454.3, 1425.4, 1273.0, 1248.0,
1035.8; LC/MS (m/z, %) ESI-(+) 341.3 (100.0) and ESI-(-) 127.1 (100.0); HRMS calcd
for [C21H26NO3]+ 340.1913, found 340.1924.
ASSOCIATED CONTENT
Supporting Information
Copies of NMR spectra, single-crystal X-ray diffraction data and crystallographic
information file (CIF) are available. This material is available free of charge via the
Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: raminelli@unifesp.br
ACKNOWLEDGMENTS
We are grateful to FAPESP (Brazil) (Fundação de Amparo à Pesquisa do Estado de
São Paulo - Brazil) for financial support and to Dr. Adelheid Hagenbach (FU-Berlin -
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Germany) for X-Ray facilities. A.F.C.R. thanks CAPES (Brazil) (Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior - Brazil) and A.C.A.M. thanks CAPES
and FAPESP for fellowships.
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REFERENCES
1. (a) Osorio, E. J.; Robledo, S. M.; Bastida, J. In The Alkaloids; Cordell, G. A., Ed.;
Academic Press: San Diego, 2008; Vol. 66, pp 126.
2. (a) Singh, I. P.; Bodiwala, H. S. Nat. Prod. Rep. 2010, 27, 1781. (b) Kashiwada, Y.;
Aoshima, A.; Ikeshiro, Y.; Chen, Y.-P.; Furukawa, H.; Itoigawa, M.; Fujioka, T.;
Mihashi, K.; Cosentino, L. M.; Morris-Natschke, S. L.; Lee, K.-H. Bioorg. Med. Chem.
2005, 13, 443.
3. (a) Wiart, C. Lead Compounds from Medicinal Plants for the Treatment of Cancer;
Academic Press: Waltham, 2013, pp 35. (b) Suresh, H. M.; Shivakumar, B.; Shivakumar,
S. I. Int. J. Plant Res. 2012, 2, 57. (c) Ponnala, S.; Chaudhary, S.; González-Sarrias, A.;
Seeram, N. P.; Harding, W. W. Bioorg. Med. Chem. Lett. 2011, 21, 4462. (d) Stévigny,
C.; Bailly, C.; Quetin-Leclercq, J. Curr. Med. Chem. Anti-Cancer Agents, 2005, 5, 173.
4. (a) Booth, R. G. In Foye´s Principles of Medicinal Chemistry, 7th ed; Lemke, T. L.;
Williams, D. A.; Roche, V. F.; Zito, S. W., Eds.; Lippincott Williams & Wilkins:
Philadelphia, 2013, pp 430. (b) Zhang, A.; Zhang, Y.; Branfman, A. R.; Baldessarini, R.
J.; Neumeyer, J. L. J. Med. Chem. 2007, 50, 171.
5. (a) Tyne, H. L.; Parsons, J.; Sinnott, A.; Fox, S. H.; Fletcher, N. A.; Steiger, M. J. J.
Neurol. 2004, 251, 1370. (b) Poewe, W.; Wenning, G. K. Mov. Disord. 2000, 15, 789.
6. (a) Eardley, I.; Donatucci, C.; Corbin, J.; El-Meliegy, A.; Hatzimouratidis, K.; McVary,
K.; Munarriz, R.; Lee, S. W. J. Sex. Med. 2010, 7, 524. (b) Hatzimouratidis, K.; Amar,
E.; Eardley, I.; Giuliano, F.; Hatzichristou, D.; Montorsi, F.; Vardi, Y.; Wespes, E. Eur.
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2
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5
6
Urol. 2010, 57, 804. (c) Hatzimouratidis, K.; Hatzichristou, D. G. Drugs 2005, 65, 1621.
(d) Hatzichristou, D. G.; Pescatori, E. S. BJU Int. 2001, 88, 11.
7
8
9
7. (a) Li, J. J. Name Reactions: A Collection of Detailed Mechanisms and Synthetic
Applications, 4th ed; Springer-Verlag: Berlin-Heidelberg, 2009, pp 450. (b) Smith, M.
B.; March, J. March’s Advanced Organic Chemistry: Reactions, Mechanisms and
Structure, 6th ed; John Wiley & Sons: Hoboken, 2007, pp 925. (c) Laali, K. K.;
Shokouhimehr, M. Curr. Org. Synth. 2009, 6, 193. (d) Leake, P. H. Chem. Rev. 1956, 56,
27.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
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41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
8. For photochemical reactions, please see: (a) Bach, T.; Hehn, J. P. Angew. Chem. Int.
Ed. 2011, 50, 1000. (b) Chuang, T.-H.; Li, C.-F.; Lee, H.-Z.; Wen, Y.-C. J. Org. Chem.
2013, 78, 4974. (c) Barolo, S. M.; Teng, X.; Cuny, G. D.; Rossi, R. A. J. Org. Chem.
2006, 71, 8493. (d) Lenz, G. R. J. Org. Chem. 1988, 53, 4447. (e) Cava, M. P.; Stern, P.;
Wakisaka, K. Tetrahedron 1973, 29, 2245. (f) Kupchan, S. M.; Moniot, J. L.; Kanojia, R.
M.; O´Brien, J. J. Org. Chem. 1971, 36, 2413.
9. For palladium-catalyzed reactions, please see: (a) Hellal, M.; Singh, S.; Cuny, G. D.
Tetrahedron 2012, 68, 1674. (b) Lee, K. M.; Kim, J. C.; Kang, P.; Lee, W. K.; Eum, H.;
Ha, H.-J. Tetrahedron 2012, 68, 883. (c) Lafrance, M.; Blaquière, N.; Fagnou, K. Eur. J.
Org. Chem. 2007, 811. (d) Campeau, L.-C.; Fagnou, K. Chem. Commun. 2006, 1253. (e)
Lafrance, M.; Blaquière, N.; Fagnou, K. Chem. Commun. 2004, 2874.
10. (a) Tadross, P. M.; Stoltz, B. M. Chem. Rev. 2012, 112, 3550. (b) Atanes, N.; Castelo,
L.; Guitián, E.; Saá, C.; Saá, J. M.; Suau, R. J. Org. Chem. 1991, 56, 2984. (c) Gómez,
B.; Martín, G.; Guitián, E.; Castedo, L.; Saá, J. M. Tetrahedron 1993, 49, 1251. (d)
Atanes, N.; Castedo, L.; Cobas, A.; Guitián, E.; Saá, C.; Saá, J. M. Tetrahedron 1989, 45,
7947.
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11. (a) Moreno, L.; Cabedo, N.; Boulangé, A.; Párraga, J.; Galán, A.; Leleu, S.; Sanz, M.-
J.; Cortes, D.; Franck, X. Eur. J. Med. Chem. 2013, 69, 69. (b) Liu, D.; Venhuis, B. J.;
Wikström, H. V.; Dijkstra, D. Tetrahedron 2007, 63, 7264.
10
11
12
13
14
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17
18
19
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21
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12. (a) Brossi, A.; Dolan, L. A.; Teitel, S. Org. Synth. 1988, Coll. Vol. 6, 1. (b) Whaley,
W. M.; Govindachari, T. R. Org. React. 1951, 6, 74. (c) Kürti, L.; Czakó, B. Strategic
Applications of Named Reactions in Organic Synthesis; Elsevier Academic Press: San
Diego, 2005, pp 62.
13. Leroy, C.; Dupas, G.; Bourguignon, J.; Quéguiner, G. Tetrahedron 1994, 50, 13135.
14. Kupchan, S. M.; Dasgupta, B.; Fujita, E.; King, M. L. Tetrahedron 1963, 19, 227.
15. Arthur, H. R.; Cheung, H. T. J. Chem. Soc. 1959, 2306.
16. Cava, M. P.; Venkateswarlu, A.; Srinivasan, M.; Edie, D. L. Tetrahedron 1972, 28,
4299.
17. Katsui, N.; Sato, K.; Tobinaga, S.; Takeuchi, N. Tetrahedron Lett. 1966, 50, 6257.
18. (a) Peña, D.; Pérez, D.; Guitián, E.; Castedo, L. J. Am. Chem. Soc. 1999, 121, 5827.
(b) Himeshima, Y.; Sonoda, T.; Kobayashi, H. Chem. Lett. 1983, 1211.
19. For examples of atropisomerism in aporphinoids, please see: (a) Zhang, A.; Zhang,
Y.; Branfman, A. R.; Baldessarini, R. J.; Neumeyer, J. L. J. Med. Chem. 2007, 50, 171.
(b) Linnanen, T.; Brisander, M.; Unelius, L.; Rosqvist, S.; Nordvall, G.; Hacksell, U.;
Johansson, A. M. J. Med. Chem. 2001, 44, 1337.
20. Correa, C.; Urzua, A.; Torres, R. Soc. Chil. Quim. 1987, 32, 105.
21. Herm, L.; Berényi, S.; Vonk, A.; Rinken, A.; Sipos, A. Bioorg. Med. Chem. 2009, 17,
4756.
22. Israilov, I. A.; Manushakyan, M. A.; Mnatsakanyan, V. A.; Yunusov, M. S.; Yunusov,
S. Yu. Khim. Prirod. Soed. 1984, 1, 81.
23. Tiwari, K. P.; Masood, M. Phytochemistry 1978, 17, 1068.
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24. Armarego, W. L. F; Perrin, D. D. Purification of Laboratory Chemicals, 4th ed;
Butterworth-Heinemann: Oxford, 1996, pp 1.
7
8
9
25. Watson, S. C.; Eastham, J. F. J. Organomet. Chem. 1967, 9, 165.
26. Leonard, J.; Lygo, B.; Procter G. Advanced Practical Organic Chemistry, 2nd ed;
CRC Press: Boca Raton, 1998, pp 102.
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27. Niederstein, Y.; Peter, M. G. Liebigs Annalen der Chemie 1989, 12, 1189.
28. Soni, R.; Cheumg, F. K.; Clarkson, G. C.; Martins, J. E. D.; Graham, M. A.; Wills,
M. Org. Biomol. Chem. 2011, 9, 3290.
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