Fast and efficient synthesis of pyrano[3,2-c]quinolines catalyzed by niobium(V) chloride

Article abstract of DOI:10.1055/s-2008-1067186

A highly efficient two-step method for the synthesis of pyranoquinoline derivatives from imino-Diels-Alder reactions between aldimines and 3,4-dihydro-2H-pyran using niobium(V) chloride as catalyst under mild conditions is described. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2008-1067186

PAPER
2527
Fast and Efficient Synthesis of Pyrano[3,2-c]quinolines Catalyzed by
Niobium(V) Chloride
S
ynthesis of Py
u
c
]q
i
zs
Carlos da Silva-Filho,a,b Valdemar Lacerda Júnior,a,c Mauricio Gomes Constantino,*a Gil Valdo José da Silvaa
a
Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo,
Av. Bandeirantes 3900, 14040-901 Ribeirão Preto, SP, Brazil
Fax +55(16)36338151; E-mail: mgconsta@usp.br
Centro de Estudos de Insetos Sociais, Instituto de Biociências, Universidade Estadual Paulista,
Av. 24A, nº 1515, 13506-900 Rio Claro, SP, Brazil
Departamento de Química, Centro de Ciências Exatas, Universidade Federal do Espirito Santo,
Av. Fernando Ferrari 514, 29060-900 Vitória, ES, Brazil
b
c
Received 10 March 2008; revised 14 April 2008
For the proposed studies, aldimines 3a–p were prepared
in good yields by treatment of the respective aromatic al-
dehydes 1a–p with aniline (2) at room temperature
(Table 1).
Abstract: A highly efficient two-step method for the synthesis of
pyranoquinoline derivatives from imino-Diels–Alder reactions be-
tween aldimines and 3,4-dihydro-2H-pyran using niobium(V) chlo-
ride as catalyst under mild conditions is described.
Key words: Diels–Alder reactions, Lewis acids, catalysis, quino-
lines, Schiff bases
Table 1 Preparation of Aldimines 3a–p
R1
O
R1
R2
R3
R2
R3
Pyranoquinoline derivatives are an important class of nat-
ural products that are present in many alkaloids.1,2 They
exhibit a wide spectrum of biological activity in various
fields,3–6 such as psychotropic, antiallergenic, anti-inflam-
matory, and estrogenic activity. In addition, these deriva-
tives are also found to posses a vast range of
pharmacological activities.7 It is therefore not surprising
that many synthetic methods have been developed for
these compounds.8–11 Among the various methods, the
imino-Diels–Alder reaction between N-arylimines and
nucleophilic alkenes is probably one of the most powerful
synthetic tools for the construction of nitrogen-containing
six-membered heterocyclic compounds.
Generally, Lewis acids11–14 are employed to catalyze such
reactions (there are also one-pot versions).15–18 However,
several Lewis acids are deactivated or decomposed by ni-
trogen-containing substrates.19 Some of the Lewis acids
are not easily available or are expensive, require longer re-
action times, and form the products with poor yields.
Therefore, developing simple and efficient synthetic
methods for the preparation of this type of compound be-
comes more and more important.
H
EtOH
N
+
r.t., 3–5 d
R5
R5
NH2
R4
R4
1a–p
3a–p
2
Starting R1
aldehyde
R2
R3
R4
R5
Time Aldimine Yield
(h)
(%)
98
95
98
96
94
92
90
93
94
96
97
96
93
95
91
90
1a
1b
1c
1d
1e
1f
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
72 3a
H
Me
H
H
72 3b
72 3c
72 3d
72 3e
96 3f
96 3g
H
Me
H
H
Me
Me
H
H
H
H
Me
H
Me
H
NO2
H
1g
1h
1i
NO2
H
H
H
OCH2O
OCH2O
NO2 120 3h
H
H
120 3i
72 3j
72 3k
72 3l
1j
H
H
Cl
H
Niobium(V) chloride, a low-cost and commercially avail-
able reagent, has been used by our group and other re-
searchers as an effective catalyst for synthetic
methodologies in a variety of reactions.20–32 In the present
report a highly efficient two-step method for the synthesis
of pyranoquinolines using niobium(V) chloride as cata-
lyst is described.
1k
1l
H
Cl
H
H
H
H
Cl
H
H
1m
1n
1o
1p
H
OMe H
Me
H
96 3m
96 3n
96 3o
120 3p
H
OMe
H
H
H
H
H
OMe
H
H
OMe OMe OMe
H
SYNTHESIS 2008, No. 16, pp 2527–2536
x
x.
x
x
.
2
0
0
8
Advanced online publication: 24.07.2008
DOI: 10.1055/s-2008-1067186; Art ID: M01408SS
© Georg Thieme Verlag Stuttgart · New York

2528
L. C. da Silva-Filho et al.
PAPER
O
O
R1
H
H
R2
NbCl5 (0.5, 0.25,
or 0.125 equiv)
R1
R1
O
N
H
H
R2
R3
R2
R3
+
+
N
H
N
H
R5
R3
MeCN, r.t.
R4
R5
R5
R4
R4
5a–p endo
3a–p
6a–p exo
4
Scheme 1 Synthesis of pyranoquinoline derivatives from the imino-Diels–Alder reaction between aldimines 3a–p and 3,4-dihydro-2H-pyran
(4) catalyzed by niobium(V) chloride
Table 2 Niobium(V) Chloride Catalyzed Synthesis of Pyranoquin-
oline Derivatives 5a–p (endo) and 6a–p (exo)
Table 2 Niobium(V) Chloride Catalyzed Synthesis of Pyranoquin-
oline Derivatives 5a–p (endo) and 6a–p (exo) (continued)
Aldimine NbCl5
(equiv)
Time
(min)
Yield
(%)
Ratio5a–p/6a–p
(endo/exo)
Aldimine NbCl5
(equiv)
Time
(min)
Yield
(%)
Ratio5a–p/6a–p
(endo/exo)
3a
3b
3c
3d
3e
3f
0.500
0.250
0.125
1
5
15
92
89
90
44:56
44:56
33:67
3n
3o
3p
0.500
0.250
0.125
5
35
100
88
86
83
41:59
37:63
26:74
0.500
0.250
0.125
1
5
15
90
90
84
44:56
39:41
22:78
0.500
0.250
0.125
10
50
180
70
67
68
36:64
26:74
23:77
0.500
0.250
0.125
1
5
15
85
85
81
31:69
31:69
22:78
0.500
0.250
0.125
15
50
190
79
80
76
35:65
20:80
07:93
0.500
0.250
0.125
1
10
15
85
87
84
31:69
28:72
13:87
Imino-Diels–Alder reactions between aldimines 3a–p and
3,4-dihydro-2H-pyran (4) in the presence of niobium(V)
chloride in acetonitrile at room temperature afforded the
corresponding pyranoquinoline derivatives 5a–p and 6a–
p in high yields. In most of the cases, a mixture of endo-
isomers 5 and exo-isomers 6 were obtained (Scheme 1,
Table 2).
0.500
0.250
0.125
30
80
150
80
81
75
0:100
0:100
0:100
0.500
0.250
0.125
1
5
10
85
82
82
49:51
48:52
43:57
All products were isolated and characterized by spectro-
scopic and spectrometric methods (1H NMR, 13C NMR,
IR, and mass spectra). The product ratios were determined
3g
3h
3i
0.500
0.250
0.125
5
20
50
79
77
74
50:50
48:52
30:70
1
by H NMR analysis of the crude product. The relative
stereochemistry of the Diels–Alder adducts was deter-
0.500
0.250
0.125
30
100
190
88
85
84
41:59
41:59
40:60
mined using the H–1H scalar coupling constant values
1
between H1 and H2 (J1,2) and comparison with literature
data. Adducts 5a–p (endo), show smaller coupling con-
stants J1,2 (5.5–5.7 Hz), typical for a gauche conformation.
This is consistent with an orientation where the pyran ring
and the phenyl group are on the same side (Figure 1). In
adducts 6a–p (exo), the coupling constants are significant-
ly higher, J1,2 between 8.1 and 11.1 Hz, indicative of the
anti orientation of H1/H2, which is only possible when the
pyran ring and the phenyl group are on opposite sides of
the quinoline ring.
0.500
0.250
0.125
15
60
150
75
72
73
46:54
34:66
18:82
3j
0.500
0.250
0.125
1
5
15
89
90
86
40:60
42:58
34:66
3k
3l
0.500
0.250
0.125
1
5
15
87
87
85
42:58
42:58
35:65
As can be observed from Table 2, in all cases the reactions
proceed smoothly to give the pyranoquinoline derivatives,
which could be separated by column chromatography.
Substitution on the aromatic ring has a remarkable influ-
ence on reactivity: methylated 3e or oxygenated 3p ald-
imines, for example, are less reactive. The use of a lower
molar ratio of niobium(V) chloride leads to an enhance-
ment of diastereoselectivity, although the required reac-
tion times are longer.
0.500
0.250
0.125
1
5
15
83
84
80
40:60
44:56
35:65
3m
0.500
0.250
0.125
5
25
75
87
81
78
40:60
19:81
0:100
Synthesis 2008, No. 16, 2527–2536 © Thieme Stuttgart · New York

PAPER
Synthesis of Pyrano[3,2-c]quinolines
2529
specified, all reagents were purchased from commercial sources and
were used without further purification.
J2,6 value: 2.3–2.8 Hz
O
J2,6 value: 2.0–2.5 Hz
O
6
N-[(E)-Arylmethylene]anilines 3a–p; General Procedure35
Aniline (2, 2 mmol) and the appropriate aromatic aldehyde (2
mmol) were dissolved together in EtOH (10 mL) and left to stand
overnight at r.t. The solvent was removed under vacuum, and the
products were dissolved in EtOH (10 mL) and left to stand at r.t. for
the time shown in Table 1. The yields were 90–98%.
H
6
H
2
2
H
H
1
1
N
N
H
H
H
H
J1,2 value: 8.1–11.1 Hz
J1,2 value: 5.5–5.7 Hz
N-[(E)-Phenylmethylene]aniline (3a)36
IR (film): 3028, 2863, 1700, 1627, 1484, 1191, 873, 767 cm–1.
5a–p
6a–p
1H NMR (400 MHz, CDCl3): d = 8.44 (s, 1 H), 7.87–7.93 (m, 2 H),
7.44–7.49 (m, 3 H), 7.36–7.42 (m, 2 H), 7.19–7.20 (m, 3 H).
Figure 1 Coupling constant values used for determining stereo-
chemistry
13C NMR (100 MHz, CDCl3): d = 160.4 (CH), 151.9 (C), 136.1 (C),
131.4 (CH), 129.1 (CH), 128.8 (CH), 128.7 (CH), 125.9 (CH),
120.9 (CH).
A remarkable aspect of this work is the higher efficiency
of niobium(V) chloride, as compared to other Lewis acid
catalysts. The strong activation of the aldimine system ex-
erted by niobium(V) chloride is demonstrated by the
shorter reaction times required. Table 3 shows some ex-
amples comparing our results for aldimine 3a with litera-
ture data using other Lewis acids.
MS: m/z (%) = 181 (M)+, 152, 149, 104, 89, 77, 63, 51.
N-[(E)-(4-Methylphenyl)methylene]aniline (3b)36
IR (film): 3039, 2869, 1623, 1484, 1173, 815, 753 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.40 (s, 1 H), 7.79 (d, J = 8.1 Hz,
2 H), 7.34–7.40 (m, 2 H), 7.26 (d, J = 8.1 Hz, 2 H), 7.18–7.23 (m, 3
H), 2.40 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 160.3 (CH), 152.2 (C), 141.8 (C),
133.7 (C), 129.5 (CH), 129.1 (CH), 128.8 (CH), 125.7 (CH), 120.9
(CH), 21.6 (CH3).
Table 3 Comparison of Imino Diels–Alder Reactions of Aldimine
3a with 3,4-Dihydro-2H-pyran Catalyzed by Various Lewis Acids
Lewis acid
NbCl5
Time (min)
Yield (%)
Ratio endo/exo
44:56
MS: m/z = 195 (M)+, 180, 152, 116, 104, 91, 77, 65, 51.
1
30
92
80
88
86
13
N-[(E)-(3-Methylphenyl)methylene]aniline (3c)37
InCl3
41:59
IR (film): 3036, 2863, 1627, 1603, 1487, 1205, 1148, 786 cm–1.
33
LiBF4
120
1020
15:85
1H NMR (400 MHz, CDCl3): d = 8.36 (s, 1 H), 7.62 (s, 1 H), 7.63
(d, J = 7.5 Hz, 1 H), 7.33–7.39 (m, 2 H), 7.31 (t, J = 7.5 Hz, 1 H),
7.24 (d, J = 7.5 Hz, 1 H), 7.15–7.22 (m, 3 H), 2.37 (s, 3 H).
K10/Fe3+ 34
42:58
13C NMR (100 MHz, CDCl3): d = 160.6 (CH), 152.1 (C), 138.4 (C),
136.1 (C), 132.2 (CH), 129.1 (CH), 129.0 (CH), 128.6 (CH), 126.4
(CH), 125.8 (CH), 120.8 (CH), 21.2 (CH3).
In summary, this paper describes an efficient two-step
method for the synthesis of pyranoquinoline derivatives
from imino Diels–Alder reactions between aldimines and
3,4-dihydro-2H-pyran (4) using niobium(V) chloride as a
catalyst. As compared to other Lewis acids (e.g., InCl3),13
niobium(V) chloride is more effective, requiring shorter
reaction times, giving in most cases better yields and good
diastereoselectivity, especially with lower molar concen-
trations of niobium(V) chloride. These notable features
make this procedure an useful and attractive process for
the synthesis of fused pyrano[3,2-c]quinolines of biologi-
cal importance.
MS: m/z = 195 (M)+, 180, 152, 116, 104, 91, 77, 65, 51
N-[(E)-(2-Methylphenyl)methylene]aniline (3d)38
IR (film): 3027, 2908, 1734, 1623, 1491, 1201, 763 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.74 (s, 1 H), 8.08 (dd, J1 = 7.5 Hz,
J2 = 1.1 Hz, 1 H), 7.18–7.42 (m, 8 H), 2.58 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 159.0 (CH), 152.6 (C), 138.5 (C),
134.1 (C), 131.0 (CH), 129.1 (CH), 127.8 (CH), 126.3 (CH), 120.9
(CH), 19.3 (CH3).
MS: m/z = 195 (M)+, 178, 152, 115, 104, 91, 77, 65, 51
N-[(E)-Mesitylmethylene]aniline (3e)39
NMR spectra were measured using a Bruker DRX 400 instrument
[400 MHz for 1H NMR and 100 MHz for the 13C NMR (proton de-
coupled)] using CDCl3 as solvent and TMS as internal standard. IR
spectra were measured with a Perkin Elmer Spectrum RX IFTIR
System, and the most intense or representative bands are reported.
EI-MS (70 eV) used a HP 5988-A spectrometer with fused silica
capillary GC columns: HP-1 (25 m × 0.2 mm i.d. × 0.33 mm phase
thickness), column temperature was 100 °C (3 min) ramped to 220
°C at 20 °C min–1. Mass spectral analyses of new compounds were
performed on a high-resolution q-TOF. ESI-MS were acquired on a
UltrOTOF apparatus (Bruker Daltonics, Billerica, MA, USA), with
flux 150 mL/h in MeCN, in positive mode. Column chromatography
was performed with silica gel (60–230 mesh, Acros). Except where
IR (film): 2953, 2917, 1588, 1450, 1194, 969, 853, 758 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.75 (s, 1 H), 7.35–7.41 (m, 2 H),
7.14–7.23 (m, 3 H), 6.90 (s, 2 H), 2.51 (s, 6 H), 2.29 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 160.8 (CH), 153.1 (C), 139.8 (C),
138.6 (C), 130.5 (C), 129.7 (CH), 129.1 (CH), 125.5 (CH), 120.7
(CH), 21.2 (CH3), 21.0 (CH3).
MS: m/z = 223 (M)+, 206, 140, 131, 115, 103, 91, 77, 65, 51.
N-[(E)-(3-Nitrophenyl)methylene]aniline (3f)39
IR (film): 3075, 2880, 2355, 1528, 1352, 1191, 814, 764 cm–1.
Synthesis 2008, No. 16, 2527–2536 © Thieme Stuttgart · New York

2530
L. C. da Silva-Filho et al.
PAPER
1H NMR (400 MHz, CDCl3): d = 8.62 (s, 1 H), 8.41 (s, 1 H), 8.20
(dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 8.14 (d, J = 8.1 Hz, 1 H), 7.54 (t,
J = 8.1 Hz, 1 H), 7.33–7.40 (m, 2 H), 7.17–7.26 (m, 3 H).
N-[(E)-(2-Chlorophenyl)methylene]aniline (3l)43
IR (film): 3056, 2926, 1616, 1565, 1487, 1442, 1272, 1190, 1052,
763 cm–1.
13C NMR (100 MHz, CDCl3): d = 157.1 (CH), 150.7 (C), 148.5 (C),
137.7 (C), 134.1 (CH), 129.7 (CH), 129.2 (CH), 126.8 (CH), 125.4
(CH), 123.1 (CH), 120.9 (CH).
1H NMR (400 MHz, CDCl3): d = 8.90 (s, 1 H), 8.23 (dd, J1 = 7.6 Hz,
J2 = 2.5 Hz, 1 H), 7.30–7.42 (m, 5 H), 7.21–7.27 (m, 3 H).
13C NMR (100 MHz, CDCl3): d = 156.8 (CH), 151.8 (C), 136.0 (C),
133.2 (C), 132.1 (CH), 129.9 (CH), 129.2 (CH), 128.5 (CH), 127.1
(CH), 126.3 (CH), 121.0 (CH).
MS: m/z = 217 (M + 2)+, 215 (M)+, 180, 152, 112, 104, 89, 77, 63,
51.
MS: m/z = 227 (M)+, 179, 152, 104, 77, 63, 51.
N-[(E)-(2-Nitrophenyl)methylene]aniline (3g)40
IR (film): 3048, 2910, 2365, 1522, 1346, 1190, 858, 767 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.93 (s, 1 H), 8.30 (dd, J1 = 7.6 Hz,
J2 = 1.3 Hz, 1 H), 8.06 (dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 7.72 (t,
J = 7.6 Hz, 1 H), 7.60 (ddd, J1 = 8.1, J2 = 7.6 Hz, J3 = 1.3 Hz, 1 H),
7.39–7.44 (m, 2 H), 7.25–7.31 (m, 3 H).
N-[(E)-(4-Methoxyphenyl)methylene]aniline (3m)36
IR (film): 3056, 2968, 2849, 1569, 1506, 1248, 1165, 1022, 843,
764 cm–1.
13C NMR (100 MHz, CDCl3): d = 155.8 (CH), 151.1 (C), 149.3 (C),
133.6 (CH), 131.2 (CH), 131.1 (C), 129.7 (CH), 129.3 (CH), 126.9
(CH), 124.5 (CH), 121.2 (CH).
1H NMR (400 MHz, CDCl3): d = 8.37 (s, 1 H), 7.84 (d, J = 8.8 Hz,
2 H), 7.34–7.40 (m, 2 H), 7.19 (d, J = 8.8 Hz, 2 H), 6.95–7.01 (m, 3
H), 3.85 (s, 3 H).
MS: m/z = 227 (M)+, 209, 195, 179, 167, 152, 77, 51.
13C NMR (100 MHz, CDCl3): d = 162.3 (C), 159.8 (CH), 152.2 (C),
130.6 (CH), 129.1 (CH), 125.6 (CH), 120.9 (CH), 114.3 (C), 114.2
(CH), 55.4 (OCH3).
N-[(E)-(6-Nitro-1,3-benzodioxol-5-yl)methylene]aniline (3h)40
IR (film): 3067, 2908, 2354, 1516, 1507, 1326, 1041, 924, 687 cm–1.
MS: m/z = 211 (M)+, 195, 167, 139, 104, 77, 63, 51.
1H NMR (400 MHz, CDCl3): d = 8.92 (s, 1 H), 7.73 (s, 1 H), 7.54
(s, 1 H), 7.39–7.44 (m, 2 H), 7.25–7.30 (m, 3 H), 6.18 (s, 2 H).
13C NMR (100 MHz, CDCl3): d = 155.7 (CH), 152.1 (C), 150.9 (C),
149.7 (C), 144.6 (C), 129.3 (CH), 128.3 (CH), 126.8 (CH), 121.2
(CH), 107.8 (CH), 105.1 (CH), 103.4 (CH2).
N-[(E)-(3-Methoxyphenyl)methylene]aniline (3n)37
IR (film): 2946, 2834, 1580, 1487, 1268, 1213, 1152, 1041, 844,
787 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.38 (s, 1 H), 7.51 (dd, J1 = 2.5 Hz,
J2 = 1.3 Hz, 1 H), 7.32–7.41 (m, 4 H), 7.17–7.24 (m, 3 H), 7.01
(ddd, J1 = 8.0, J2 = 2.8 Hz, J3 = 1.3 Hz, 1 H), 3.83 (s, 3 H).
MS: m/z = 271 (M)+, 253, 222, 167, 139, 93, 77, 51.
N-[(E)-1,3-Benzodioxol-5-ylmethylene]aniline (3i)41
13C NMR (100 MHz, CDCl3): d = 160.2 (CH), 160.0 (C), 151.9 (C),
137.6 (C), 129.7 (CH), 129.1 (CH), 125.9 (CH), 122.3 (CH), 120.9
(CH), 118.3 (CH), 111.9 (CH), 55.3 (OCH3).
IR (film): 2879, 1584, 1436, 1264, 1042, 936, 767 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.32 (s, 1 H), 7.53 (d, J = 1.5 Hz,
1 H), 7.35–7.41 (m, 2 H), 7.27 (dd, J1 = 7.8 Hz, J2 = 1.5 Hz, 1 H),
7.15–7.23 (m, 3 H), 6.87 (d, J = 7.8 Hz, 1 H), 6.02 (s, 2 H).
13C NMR (100 MHz, CDCl3): d = 159.4 (CH), 152.6 (C), 149.9 (C),
147.7 (C), 134.1 (C), 129.1 (CH), 125.9 (CH), 125.8 (CH), 120.9
(CH), 108.2 (CH), 106.9 (CH), 101.6 (CH2).
MS: m/z = 211 (M)+, 198, 181, 167, 139, 116, 104, 92, 77, 63, 51.
N-[(E)-(2-Methoxyphenyl)methylene]aniline (3o)38
IR (film): 2926, 2837, 1589, 14917, 1286, 1252, 1187, 1025, 758
cm–1.
1H NMR (400 MHz, CDCl3): d = 8.91 (s, 1 H), 8.16 (dd, J1 = 7.6 Hz,
J2 = 1.6 Hz, 1 H), 7.44 (ddd, J1 = 8.5 Hz, J2 = 7.6 Hz, J3 = 1.8 Hz, 1
H), 7.35–7.40 (m, 2 H), 7.17–7.25 (m, 3 H), 7.01 (t, J = 7.6 Hz, 1
H), 6.94 (d, J = 8.5 Hz, 1 H), 3.87 (s, 3 H).
13C NMR (100 MHz, CDCl3): d = 159.5 (C), 156.6 (CH), 152.6 (C),
136.0 (CH), 132.8 (CH), 129.1 (CH), 127.6 (CH), 125.7 (CH),
124.6 (CH), 120.9 (CH), 111.1 (CH), 55.5 (OCH3).
MS: m/z = 225 (M)+, 194, 166, 139, 121, 104, 93, 77, 63, 51.
N-[(E)-(4-Chlorophenyl)methylene]aniline (3j)36
IR (film): 3056, 2869, 1623, 1490, 1405, 1088, 1013, 763 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.39 (s, 1 H), 7.82 (d, J = 8.3 Hz,
2 H), 7.43 (d, J = 8.3 Hz, 2 H), 7.35–7.41 (m, 2 H), 7.16–7.27 (m, 3
H).
13C NMR (100 MHz, CDCl3): d = 158.8 (CH), 151.6 (C), 137.3 (C),
134.7 (C), 129.9 (CH), 129.2 (CH), 129.1 (CH), 126.2 (CH), 120.8
(CH).
MS: m/z = 217 (M + 2)+, 215 (M)+, 178, 152, 137, 104, 89, 77, 63,
51.
MS: m/z = 211 (M)+, 198, 180, 167, 139, 119, 104, 93, 77, 63, 51.
N-[(E)-(3,4,5-Trimethoxyphenyl)methylene]aniline (3p)44
IR (film): 3067, 2908, 2354, 1516, 1507, 1326, 1041, 924, 687 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.34 (s, 1 H), 7.36–7.42 (m, 2 H),
7.19–7.24 (m, 3 H), 7.16 (s, 2 H), 3.93 (s, 6 H), 3.91 (s, 3 H).
N-[(E)-(3-Chlorophenyl)methylene]aniline (3k)42
13C NMR (100 MHz, CDCl3): d = 159.9 (CH), 153.5 (C), 151.6 (C),
141.1 (C), 131.5 (C), 129.2 (CH), 126.0 (CH), 120.9 (CH), 105.9
(CH), 61.0 (OCH3), 56.3 (OCH3).
IR (film): 3061, 2873, 1623, 1569, 1487, 1188, 1074, 763 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.27 (s, 1 H), 7.86 (s, 1 H), 7.64
(d, J = 7.8 Hz, 1 H), 7.31–7.37 (m, 3 H), 7.28 (t, J = 7.8 Hz, 1 H),
7.14–7.22 (m, 3 H).
MS: m/z = 271 (M)+, 256, 225, 196, 153, 104, 93, 77, 66, 51.
5-Aryl-3,4,4a,5,6,10b-hexahydro-2H-pyrano[3,2-c]quinolines 5
and 6; General Procedure
13C NMR (100 MHz, CDCl3): d = 158.5 (CH), 151.3 (C), 137.8 (C),
134.8 (C), 131.1 (CH), 129.9 (CH), 129.1 (CH), 128.2 (CH), 127.1
(CH), 126.3 (CH), 120.8 (CH).
MS: m/z = 217 (M + 2)+, 215 (M)+, 196, 194, 180, 151, 112, 104,
89, 77, 63, 51.
To a soln of NbCl5 (0.500, 0.250 or 0.125 mmol) in anhyd MeCN
(1.0 mL), maintained at r.t., under N2 atmosphere, was added a soln
of the aldimine (1.0 mmol) and DHP (4, 2 mmol) in anhyd MeCN
(2.0 mL). The mixture was quenched with 10% aq citric acid (2.0
mL). The mixture was diluted with H2O (5.0 mL) and EtOAc (10.0
mL), the organic layer was separated and washed with 5% aq
Synthesis 2008, No. 16, 2527–2536 © Thieme Stuttgart · New York

PAPER
Synthesis of Pyrano[3,2-c]quinolines
2531
NaHCO3 (3 × 10.0 mL), sat. brine (2 × 10.0 mL), and dried (anhyd
MgSO4). The solvent was removed under vacuum and the products
were purified by column chromatography (silica gel, hexane–
EtOAc, 9.5:0.5).
4.68 (d, J = 10.9 Hz, 1 H), 4.39 (d, J = 2.3 Hz, 1 H), 4.10 (m, 1 H),
3.72 (td, J1 = 11.6 Hz, J2 = 1.8 Hz, 1 H), 2.36 (s, 3 H), 2.07 (m, 1
H), 1.83 (tdt, J1 = 13.6 Hz, J2 = 12.4 Hz, J3 = 4.5 Hz, 1 H), 1.64 (tt,
J1 = 13.6 Hz, J2 = 4.5 Hz, 1 H), 1.48 (m, 1 H), 1.32 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 143.7 (C), 138.1 (C), 136.5 (C),
129.8 (CH), 128.3 (CH), 128.2 (CH), 126.6 (CH), 119.6 (C), 116.3
(CH), 113.1 (CH), 73.5 (CH), 67.6 (CH2), 53.4 (CH), 37.7 (CH),
23.0 (CH2), 20.9 (CH2), 20.1 (CH3).
rac-(4aS,5S,10bS)-5-Phenyl-3,4,4a,5,6,10b-hexahydro-2H-pyr-
ano[3,2-c]quinoline (5a)11,45,46
IR (film): 3312, 2941, 2865, 1608, 1486, 1317, 1265, 1069, 737
cm–1.
MS: m/z = 279 (M)+, 249, 235, 221, 203, 188, 91, 77, 51.
1H NMR (400 MHz, CDCl3): d = 7.35–7.44 (m, 5 H), 7.30 (m, 1 H),
7.09 (td, J1 = 7.7 Hz, J2 = 0.8 Hz, 1 H), 6.79 (td, J1 = 7.7 Hz,
J2 = 1.0 Hz, 1 H), 6.60 (dd, J1 = 7.7 Hz, J2 = 0.8 Hz, 1 H), 5.33 (d,
J = 5.6 Hz, 1 H), 4.69 (d, J = 2.3 Hz, 1 H), 3.85 (NH, 1 H), 3.58 (m,
1 H), 3.43 (td, J1 = 11.6 Hz, J2 = 2.5 Hz, 1 H), 2.16 (m, 1 H), 1.47–
1.58 (m, 2 H), 1.43 (m, 1 H), 1.31 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 145.6 (C), 141.5 (C), 129.2 (CH),
128.8 (CH), 128.7 (CH), 128.5 (CH), 128.0 (CH), 127.9 (CH),
127.2 (CH), 120.3 (C), 118.7 (CH), 114.8 (CH), 73.2 (CH), 61.0
(CH2), 59.7 (CH), 39.3 (CH), 25.8 (CH2), 18.4 (CH2).
rac-(4aS,5S,10bS)-5-(3-Methylphenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (5c)
IR (film): 3373, 2937, 2855, 1610, 1488, 1365, 1080, 914, 748 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.19–7.29 (m, 3 H), 7.42 (dt,
J1 = 7.7 Hz, J2 = 1.3 Hz, 1 H), 7.11 (d, J = 6.8 Hz, 1 H), 7.08 (m, 1
H), 6.79 (td, J1 = 7.6 Hz, J2 = 1.0 Hz, 1 H), 6.60 (dd, J1 = 8.1 Hz,
J2 = 1.0 Hz, 1 H), 5.32 (d, J = 5.6 Hz, 1 H), 4.65 (d, J = 2.5 Hz, 1
H), 3.94 (NH, 1 H), 3.59 (ddt, J1 = 11.4, J2 = 4.0 Hz, J3 = 2.0 Hz, 1
H), 3.43 (td, J1 = 11.4 Hz, J2 = 2.5 Hz, 1 H), 2.36 (s, 3 H), 2.16 (m,
1 H), 1.47–1.59 (m, 2 H), 1.43 (m, 1 H), 1.32 (m, 1 H).
MS: m/z = 265 (M)+, 234, 220, 194, 129, 117, 91, 77.
13C NMR (100 MHz, CDCl3): d = 146.4 (C), 142.2 (C), 139.2 (C),
129.4 (CH), 129.3 (CH), 129.2 (CH), 128.9 (CH), 128.7 (CH),
125.0 (CH), 121.1 (C), 119.4 (CH), 115.5 (CH), 73.9 (CH), 61.8
(CH2), 60.4 (CH), 40.0 (CH), 26.6 (CH2), 22.7 (CH3), 19.2 (CH2).
rac-(4aS,5R,10bS)-5-Phenyl-3,4,4a,5,6,10b-hexahydro-2H-pyr-
ano[3,2-c]quinoline (6a)11,45,46
IR (film): 3360, 2940, 2865, 1610, 1488, 1315, 1265, 1070, 737
cm–1.
MS: m/z = 279 (M)+, 249, 235, 221, 203, 188, 91, 77, 51.
1H NMR (400 MHz, CDCl3): d = 7.30–7.44 (m, 5 H), 7.22 (dd,
J1 = 7.7 Hz, J2 = 1.3 Hz, 1 H), 7.09 (td, J1 = 7.7 Hz, J2 = 1.3 Hz, 1
H), 6.71 (td, J1 = 7.3 Hz, J2 = 0.7 Hz, 1 H), 6.53 (dd, J1 = 7.7 Hz,
J2 = 0.7 Hz, 1 H), 4.72 (d, J = 10.9 Hz, 1 H), 4.39 (d, J = 2.8 Hz, 1
H), 4.10 (dt, J1 = 11.4 Hz, J2 = 2.3 Hz, 1 H), 3.72 (td, J1 = 11.4 Hz,
J2 = 2.5 Hz, 1 H), 2.11 (m, 1 H), 1.84 (tdt, J1 = 13.4 Hz, J2 = 12.4
Hz, J3 = 4.5 Hz, 1 H), 1.65 (tt, J1 = 13.4 Hz, J2 = 4.5 Hz, 1 H), 1.47
(m, 1 H), 1.33 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 145.1 (C), 142.7 (C), 131.3 (CH),
129.8 (CH), 129.0 (CH), 128.3 (CH), 128.2 (CH), 121.0 (C), 117.9
(CH), 114.5 (CH), 74.9 (CH), 69.0 (CH2), 55.2 (CH), 39.3 (CH),
24.5 (CH2), 22.4 (CH2).
HRMS (ESI): m/z [M + H] calcd for C19H22NO: 280.1695; found:
280.1699.
rac-(4aS,5R,10bS)-5-(3-Methylphenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (6c)
IR (film): 3374, 2940, 2865, 1607, 1488, 1365, 1088, 737 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.19–7.28 (m, 4 H), 7.13 (d,
J = 7.3 Hz, 1 H), 7.08 (ddd, J1 = 8.1, J2 = 7.3 Hz, J3 = 1.5 Hz, 1 H),
6.71 (t, J = 7.3 Hz, 1 H), 6.51 (d, J = 8.1 Hz, 1 H), 4.68 (d, J = 10.9
Hz, 1 H), 4.39 (d, J = 2.5 Hz, 1 H), 4.10 (m, 1 H), 3.71 (td, J1 = 11.6
Hz, J2 = 2.5 Hz, 1 H), 2.36 (s, 3 H), 2.09 (m, 1 H), 1.84 (tdt,
J1 = 13.4, J2 = 12.4 Hz, J3 = 4.3 Hz, 1 H), 1.65 (tt, J1 = 13.4 Hz,
J2 = 4.5 Hz, 1 H), 1.49 (m, 1 H), 1.33 (m, 1 H).
MS: m/z = 265 (M)+, 234, 220, 194, 129, 117, 91, 77.
13C NMR (100 MHz, CDCl3): d = 144.9 (C), 142.5 (C), 138.7 (C),
131.3 (CH), 129.8 (CH), 129.1 (CH), 128.9 (CH), 128.8 (CH),
125.4 (CH), 121.3 (C), 118.0 (CH), 114.7 (CH), 75.0 (CH), 69.1
(CH2), 55.2 (CH), 39.1 (CH), 24.6 (CH2), 22.4 (CH2), 21.9 (CH3).
rac-(4aS,5S,10bS)-5-(4-Methylphenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (5b)47
IR (film): 3307, 2926, 2861, 1608, 1505, 1318, 12645, 1071 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.41 (dt, J1 = 7.5 Hz, J2 = 1.0 Hz,
1 H), 7.29 (d, J = 7.8 Hz, 2 H), 7.18 (d, J = 7.8 Hz, 2 H), 7.08 (dddd,
J1 = 8.0 Hz, J2 = 7.5, J3 = 1.5 Hz, J4 = 1.0 Hz, 1 H), 6.78 (td,
J1 = 7.5 Hz, J2 = 1.0 Hz, 1 H), 6.58 (dd, J1 = 8.0 Hz, J2 = 1.0 Hz, 1
H), 5.31 (d, J = 5.7 Hz, 1 H), 4.65 (d, J = 2.4 Hz, 1 H), 3.93 (NH, 1
H), 3.58 (dtt, J1 = 11.4, J2 = 4.0 Hz, J3 = 1.8 Hz, 1 H), 3.42 (td,
J1 = 11.4 Hz, J2 = 2.7 Hz, 1 H), 2.36 (s, 3 H), 2.13 (dddd, J1 = 11.9
Hz, J2 = 5.7 Hz, J3 = 4.3 Hz, J4 = 2.7 Hz, 1 H), 1.46–1.56 (m, 2 H),
1.42 (m, 1 H), 1.32 (m, 1 H).
MS: m/z = 279 (M)+, 249, 235, 221, 203, 188, 91, 77, 51.
HRMS (ESI): m/z [M + H] calcd for C19H22NO: 280.1695; found:
280.1698.
rac-(4aS,5S,10bS)-5-(2-Methylphenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (5d)
IR (film): 3373, 2940, 2865, 1608, 1486, 1316, 1265, 1088, 736
cm–1.
13C NMR (100 MHz, CDCl3): d = 145.5 (C), 140.3 (C), 139.4 (C),
131.3 (CH), 130.3 (CH), 129.9 (CH), 129.0 (CH), 122.1 (C), 120.4
(CH), 116.6 (CH), 75.0 (CH), 62.9 (CH2), 61.3 (CH), 41.2 (CH),
27.7 (CH2), 23.4 (CH3), 20.3 (CH2).
1H NMR (400 MHz, CDCl3): d = 7.62 (d, J = 6.6 Hz, 1 H), 7.45 (d,
J = 7.3 Hz, 1 H), 7.19–7.25 (m, 3 H), 7.10 (t, J = 7.3 Hz, 1 H), 6.81
(t, J = 7.3 Hz, 1 H), 6.62 (d, J = 7.3 Hz, 1 H), 5.32 (d, J = 5.6 Hz, 1
H), 4.89 (d, J = 2.2 Hz, 1 H), 3.60 (ddt, J1 = 11.5 Hz, J2 = 4.1 Hz,
J3 = 2.0 Hz, 1 H), 3.43 (td, J1 = 11.5 Hz, J2 = 2.6 Hz, 1 H), 2.34 (s,
3 H), 2.18 (m, 1 H), 1.49–1.67 (m, 3 H), 1.34 (m, 1 H).
MS: m/z = 279 (M)+, 249, 235, 221, 203, 188, 91, 77, 51.
13C NMR (100 MHz, CDCl3): d = 138.6 (C), 135.02 (C), 130.7
(CH), 128.1 (CH), 127.7 (CH), 127.3 (C), 127.2 (CH), 126.5 (CH),
125.7 (CH), 118.3 (CH), 114.5 (CH), 99.6 (C), 72.8 (CH), 60.8
(CH2), 55.4 (CH), 35.6 (CH), 25.5 (CH2), 18.9 (CH3), 18.3 (CH2).
rac-(4aS,5R,10bS)-5-(4-Methylphenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (6b)47
IR (film): 3328, 2942, 2850, 1611, 1486, 1366, 1080, 736 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.30 (d, J = 7.7 Hz, 2 H), 7.21 (d,
J = 7.4 Hz, 1 H), 7.18 (d, J = 7.7Hz, 2 H), 7.07 (dd, J1 = 7.6 Hz,
J2 = 7.4 Hz, 1 H), 6.69 (t, J = 7.4 Hz, 1 H), 6.51 (d, J = 7.6 Hz, 1 H),
MS: m/z = 279 (M)+, 249, 235, 221, 203, 188, 91, 77, 51.
Synthesis 2008, No. 16, 2527–2536 © Thieme Stuttgart · New York

2532
L. C. da Silva-Filho et al.
PAPER
HRMS (ESI): m/z [M + H] calcd for C19H22NO: 280.1695; found:
280.1699.
1 H), 7.55 (dd, J1 = 8.0 Hz, J2 = 7.8 Hz, 1 H), 7.23 (dd, J1 = 7.5 Hz,
J2 = 1.4 Hz, 1 H), 7.12 (ddd, J1 = 8.1 Hz, J2 = 7.5 Hz, J3 = 1.4 Hz, 1
H), 6.75 (td, J1 = 7.5 Hz, J2 = 1.0 Hz, 1 H), 6.57 (d, J = 8.1 Hz, 1 H),
4.83 (d, J = 10.6 Hz, 1 H), 4.40 (d, J = 2.8 Hz, 1 H), 4.11 (m, 1 H),
3.74 (td, J1 = 11.5 Hz, J2 = 2.0 Hz, 1 H), 2.11 (m, 1 H), 1.84 (m, 1
H), 1.70 (tt, J1 = 13.8 Hz, J2 = 5.0 Hz, 1 H), 1.40 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 148.6 (C), 144.8 (C), 144.7 (C),
134.0 (CH), 130.9 (CH), 129.6 (CH), 129.5 (CH), 123.0 (CH),
122.7 (CH), 120.7 (C), 118.2 (CH), 114.4 (CH), 74.1 (CH), 68.5
(CH2), 54.5 (CH), 39.0 (CH), 24.1 (CH2), 22.1 (CH2).
rac-(4aS,5R,10bS)-5-(2-Methylphenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (6d)
IR (film): 3374, 2936, 2865, 1609, 1485, 1320, 1264, 1088, 736
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.46 (d, J = 4.4 Hz, 1 H), 7.28 (d,
J = 7.6 Hz, 1 H), 7.23 (s, 3 H), 7.12 (t, J = 7.6 Hz, 1 H), 6.75 (t,
J = 7.6 Hz, 1 H), 6.54 (d, J = 8.1 Hz, 1 H), 5.00 (d, J = 10.3 Hz, 1
H), 4.49 (d, J = 2.6 Hz, 1 H), 4.10 (d, J = 10.9 Hz, 1 H), 3.74 (td,
J1 = 10.9 Hz, J2 = 1.9 Hz, 1 H), 2.50 (s, 3 H), 2.29 (m, 1 H), 1.88–
1.66 (m, 2 H), 1.56 (m, 1 H), 1.43 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 144.9 (C), 140.5 (C), 136.9 (C),
131.2 (CH), 131.1 (CH), 129.7 (CH), 128.2 (CH), 127.9 (CH),
126.9 (CH), 120.9 (C), 117.9 (CH), 114.5 (CH), 74.7 (CH), 68.4
(CH2), 51.5 (CH), 38.1 (CH), 24.5 (CH2), 23.3 (CH2), 20.4 (CH3).
MS: m/z = 310 (M)+, 266, 251, 205, 179, 130, 115, 91, 77, 65, 51.
rac-(4aS,5S,10bS)-5-(2-Nitrophenyl)-3,4,4a,5,6,10b-hexahydro-
2H-pyrano[3,2-c]quinoline (5g)
IR (film): 3373, 2939, 2850, 1608, 1526, 1505, 1352, 1265, 1073,
736 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.97 (dd, J1 = 7.6 Hz, J2 = 1.0 Hz,
1 H), 7.95 (dd, J1 = 8.0 Hz, J2 = 1.3 Hz, 1 H), 7.64 (td, J1 = 7.6 Hz,
J2 = 1.0 Hz, 1 H), 7.46 (ddd, J1 = 8.0 Hz, J2 = 7.6 Hz, J3 = 1.0 Hz, 1
H), 7.44 (d, J = 7.6 Hz, 1 H), 7.10 (dd, J1 = 8.1 Hz, J2 = 7.6 Hz, 1
H), 6.83 (t, J = 7.6 Hz, 1 H), 6.61 (d, J = 8.1 Hz, 1 H), 5.34 (d,
J = 5.5 Hz, 1 H), 5.15 (d, J = 2.0 Hz, 1 H), 3.60 (m, 1 H), 3.43 (td,
J1 = 11.6 Hz, J2 = 2.5 Hz, 1 H), 2.52 (m, 1 H), 1.51–1.70 (m, 2 H),
1.46 (m, 1 H), 1.32 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 148.5 (C), 144.5 (C), 135.5 (C),
132.3 (CH), 129.1 (CH), 128.0 (CH), 127.8 (CH), 127.5 (CH),
124.5 (CH), 120.2 (C), 118.8 (CH), 114.6 (CH), 72.0 (CH), 60.2
(CH2), 54.2 (CH), 36.0 (CH), 25.0 (CH2), 18.2 (CH2).
MS: m/z = 279 (M)+, 249, 235, 221, 203, 188, 91, 77, 51.
HRMS (ESI): m/z [M + H] calcd for C19H22NO: 280.1695; found:
280.1689.
rac-(4aS,5R,10bS)-5-Mesityl-3,4,4a,5,6,10b-hexahydro-2H-pyr-
ano[3,2-c]quinoline (5e)
IR (film): 3384, 2944, 2853, 1610, 1496, 1365, 1265, 1080, 736
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.22 (dd, J1 = 7.3 Hz, J2 = 1.5 Hz,
1 H), 7.07 (ddd, J1 = 8.1 Hz, J2 = 7.3 Hz, J3 = 1.5 Hz, 1 H), 6.86 (s,
2 H), 6.68 (td, J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 6.48 (dd, J1 = 8.1 Hz,
J2 = 1.0 Hz, 1 H), 5.21 (d, J = 11.6 Hz, 1 H), 4.39 (d, J = 2.8 Hz, 1
H), 4.11 (dd, J1 = 11.4 Hz, J2 = 4.0 Hz, 1 H), 3.88 (NH, 1 H), 3.69
(td, J1 = 11.4 Hz, J2 = 2.2 Hz, 1 H), 2.64 (m, 1 H), 2.45 (s, 6 H), 2.27
(s, 3 H), 1.66–1.77 (m, 2 H), 1.47–1.60 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 145.4 (C), 136.9 (C), 133.5 (C),
131.3 (CH), 129.3 (CH), 120.9 (C), 117.1 (CH), 114.3 (CH), 75.4
(CH), 68.9 (CH2), 50.0 (CH), 34.6 (CH), 23.9 (CH2), 22.4 (CH2),
21.3 (CH3), 20.7 (2 CH3).
MS: m/z = 310 (M)+, 266, 251, 217, 204, 188, 130, 115, 89, 77, 63,
51.
HRMS (ESI): m/z [M + H] calcd for C18H19N2O3: 311.1390; found:
311.1367.
rac-(4aS,5R,10bS)-5-(2-Nitrophenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (6g)
IR (film): 3373, 2939, 2850, 1608, 1526, 1505, 1352, 1265, 1073,
736 cm–1.
MS: m/z = 307 (M)+, 277, 263, 249, 231, 188, 119, 91, 77, 51.
1H NMR (400 MHz, CDCl3): d = 7.81 (dd, J1 = 8.1 Hz, J2 = 1.0 Hz,
1 H), 7.67 (dd, J1 = 7.8 Hz, J2 = 1.0 Hz, 1 H), 7.57 (td, J1 = 7.8 Hz,
J2 = 1.5 Hz, 1 H), 7.43 (ddd, J1 = 8.1 Hz, J2 = 7.8 Hz, J3 = 1.5 Hz, 1
H), 7.28 (dd, J1 = 7.6 Hz, J2 = 1.5 Hz, 1 H), 7.13 (ddd, J1 = 8.1 Hz,
J2 = 7.6 Hz, J3 = 1.5 Hz, 1 H), 6.76 (td, J1 = 7.6 Hz, J2 = 1.0 Hz, 1
H), 6.59 (d, J = 8.1 Hz, 1 H), 5.14 (d, J = 8.1 Hz, 1 H), 4.46 (d,
J = 3.6 Hz, 1 H), 4.25 (NH, 1 H), 3.88 (m, 1 H), 3.64 (ddd, J1 = 11.4
Hz, J2 = 8.4 Hz, J3 = 2.9 Hz, 1 H), 2.24 (m, 1 H), 1.77 (m, 1 H), 1.62
(m, 1 H), 1.41–1.50 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 149.9 (C), 143.9 (C), 137.2 (C),
132.9 (CH), 129.8 (CH), 129.4 (CH), 129.2 (CH), 128.4 (CH),
124.0 (CH), 119.8 (C), 119.0 (CH), 114.1 (CH), 72.2 (CH), 61.8
(CH2), 50.8 (CH), 36.7 (CH), 24.5 (CH2), 23.1 (CH2).
HRMS (ESI): m/z [M + H] calcd for C21H26NO: 308.2008; found:
308.2024.
rac-(4aS,5S,10bS)-5-(3-Nitrophenyl)-3,4,4a,5,6,10b-hexahydro-
2H-pyrano[3,2-c]quinoline (5f)47
IR (film): 3369, 2950, 2857, 1606, 1528, 1349, 1087, 759 cm–1.
1H NMR (400 MHz, CDCl3): d = 8.32 (t, J = 2.0 Hz, 1 H), 8.16
(ddd, J1 = 8.0 Hz, J2 = 2.0 Hz, J3 = 1.0 Hz, 1 H), 7.76 (d, J = 7.8 Hz,
1 H), 7.56 (dd, J1 = 8.0 Hz, J2 = 7.8 Hz, 1 H), 7.42 (d, J = 7.3 Hz, 1
H), 7.12 (dd, J1 = 7.8 Hz, J2 = 7.3 Hz, 1 H), 6.84 (td, J1 = 7.3 Hz,
J2 = 0.8 Hz, 1 H), 6.67 (dd, J1 = 7.8 Hz, J2 = 1.0 Hz, 1 H), 5.34 (d,
J = 5.6 Hz, 1 H), 4.79 (d, J = 2.3 Hz, 1 H), 3.94 (NH, 1 H), 3.59 (m,
1 H), 3.43 (td, J1 = 11.4 Hz, J2 = 2.5 Hz, 1 H), 2.20 (m, 1 H), 1.46–
1.63 (m, 2 H), 1.44 (m, 1 H), 1.19 (m, 1 H).
MS: m/z = 310 (M)+, 266, 251, 217, 204, 188, 130, 115, 89, 77, 63,
51.
13C NMR (100 MHz, CDCl3): d = 148.4 (C), 144.5 (C), 143.5 (C),
133.0 (CH), 129.4 (CH), 128.3 (CH), 127.6 (CH), 122.6 (CH),
121.7 (CH), 119.9 (C), 119.1 (CH), 114.9 (CH), 72.4 (CH), 60.6
(CH2), 58.8 (CH), 38.8 (CH), 25.26 (CH2), 17.9 (CH2).
HRMS (ESI): m/z [M + H] calcd for C18H19N2O3: 311.1390; found:
311.1390.
rac-(4aS,5S,10bS)-5-(6-Nitro-1,3-benzodioxol-5-yl)-
3,4,4a,5,6,10b-hexahydro-2H-pyrano[3,2-c]quinoline (5h)
IR (film): 3374, 2925, 1732, 1480, 1333, 1269, 1036, 737 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.53 (s, 1 H), 7.44 (dd, J1 = 7.4 Hz,
J2 = 1.5 Hz, 1 H), 7.42 (s, 1 H), 7.09 (dddd, J1 = 8.1 Hz, J2 = 7.4 Hz,
J3 = 1.5 Hz, J4 = 0.7 Hz, 1 H), 6.83 (td, J1 = 7.4 Hz, J2 = 1.0 Hz, 1
H), 6.60 (dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 6.14 (d, J = 1.2 Hz, 1
H), 6.12 (d, J = 1.2 Hz, 1 H), 5.33 (d, J = 5.6 Hz, 1 H), 5.18 (d,
MS: m/z = 310 (M)+, 266, 251, 205, 179, 130, 115, 91, 77, 65, 51.
rac-(4aS,5R,10bS)-5-(3-Nitrophenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (6f)47
IR (film): 3386, 2943, 2828, 1608, 1524, 1482, 1344, 1059, 759
cm–1.
1H NMR (400 MHz, CDCl3): d = 8.31 (t, J = 1.8 Hz, 1 H), 8.18
(ddd, J1 = 8.1 Hz, J2 = 2.3 Hz, J3 = 1.0 Hz, 1 H), 7.76 (d, J = 7.8 Hz,
Synthesis 2008, No. 16, 2527–2536 © Thieme Stuttgart · New York

PAPER
Synthesis of Pyrano[3,2-c]quinolines
2533
J = 2.0 Hz, 1 H), 3.60 (m, 1 H), 3.42 (td, J1 = 11.4 Hz, J2 = 2.0 Hz,
MS: m/z = 309 (M)+, 279, 265, 225, 233, 218, 188, 121, 91, 77, 51.
1 H), 2.53 (m, 1 H), 1.55–1.64 (m, 2 H), 1.48 (m, 1 H), 1.37 (m, 1
H).
13C NMR (100 MHz, CDCl3): d = 151.6 (C), 147.0 (C), 144.8 (C),
142.6 (C), 133.6 (C), 128.0 (CH), 127.8 (CH), 120.6 (C), 119.1
(CH), 115.0 (CH), 108.2 (CH), 105.9 (CH), 103.0 (CH2), 72.3 (CH),
60.5 (CH2), 54.7 (CH), 36.2 (CH), 25.3 (CH2), 18.7 (CH2).
rac-(4aS,5S,10bS)-5-(4-Chlorophenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (5j)49,50
IR (film): 3387, 2940, 1604, 1486, 1276, 1085, 1014, 750 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.42 (dt, J1 = 7.3 Hz, J2 = 1.5 Hz,
1 H), 7.35 (s, 4 H), 7.09 (dddd, J1 = 8.1 Hz, J2 = 7.3 Hz, J3 = 1.5 Hz,
J4 = 0.8 Hz, 1 H), 6.80 (td, J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 6.60 (dd,
J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 5.30 (d, J = 5.6 Hz, 1 H), 4.65 (d,
J = 2.5 Hz, 1 H), 3.80 (NH, 1 H), 3.59 (ddt, J1 = 11.4 Hz, J2 = 4.0
Hz, J3 = 2.0 Hz, 1 H), 3.42 (td, J1 = 11.4 Hz, J2 = 2.5 Hz, 1 H), 2.12
(m, 1 H), 1.41–1.55 (m, 3 H), 1.26 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 144.9 (C), 139.6 (C), 133.1 (C),
128.5 (CH), 128.1 (CH), 127.6 (CH), 119.9 (C), 118.6 (CH), 114.5
(CH), 72.6 (CH), 60.6 (CH2), 58.8 (CH), 38.9 (CH), 25.3 (CH2),
17.9 (CH2).
MS: m/z = 354 (M)+, 324, 310, 296, 279, 194, 188, 164, 91, 77, 51.
HRMS (ESI): m/z [M + H] calcd for C19H19N2O5: 355.1288; found:
355.1298.
rac-(4aS,5R,10bS)-5-(6-Nitro-1,3-benzodioxol-5-yl)-
3,4,4a,5,6,10b-hexahydro-2H-pyrano[3,2-c]quinoline (6h)
IR (film): 3375, 2930, 1729, 1479, 1331, 1271, 1036, 737 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.37 (s, 1 H), 7.27 (dd, J1 = 7.6 Hz,
J2 = 1.5 Hz, 1 H), 7.12 (ddd, J1 = 8.1 Hz, J2 = 7.6 Hz, J3 = 1.5 Hz, 1
H), 7.04 (s, 1 H), 6.76 (td, J1 = 7.6 Hz, J2 = 1.0 Hz, 1 H), 6.58 (dd,
J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 6.09 (d, J = 1.0 Hz, 1 H), 6.08 (d,
J = 1.0 Hz, 1 H), 5.19 (d, J = 7.6 Hz, 1 H), 4.48 (d, J = 3.8 Hz, 1 H),
3.85 (m, 1 H), 3.63 (ddd, J1 = 11.4 Hz, J2 = 8.1 Hz, J3 = 3.0 Hz, 1
H), 2.16 (m, 1 H), 1.78 (m, 1 H), 1.59 (m, 1 H), 1.43–1.52 (m, 2 H).
13C NMR (100 MHz, CDCl3): d = 151.8 (C), 147.1 (C), 143.8 (C),
142.9 (C), 134.7 (C), 129.7 (CH), 129.1 (CH), 119.7 (C), 118.0
(CH), 114.0 (CH), 107.8 (CH), 105.2 (CH), 102.9 (CH2), 71.5 (CH),
60.4 (CH2), 51.1 (CH), 37.8 (CH), 24.5 (CH2), 23.3 (CH2).
MS: m/z = 301 (M + 2)+, 299 (M)+, 268, 266, 240, 217, 154, 127,
115, 89, 77, 63, 51.
rac-(4aS,5R,10bS)-5-(4-Chlorophenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (6j)49,50
IR (film): 3364, 2935, 2851, 1609, 1486, 1262, 1050, 913, 750 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.35 (d, J = 1.4 Hz, 4 H), 7.22 (dd,
J1 = 7.3 Hz, J2 = 1.5 Hz, 1 H), 7.09 (ddd, J1 = 8.1 Hz, J2 = 7.3 Hz,
J3 = 1.5 Hz, 1 H), 6.72 (td, J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 6.53 (dd,
J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 4.69 (d, J = 10.6 Hz, 1 H), 4.38 (d,
J = 2.8 Hz, 1 H), 4.09 (m, 1 H), 3.72 (td, J1 = 11.4 Hz, J2 = 2.3 Hz,
1 H), 2.04 (m, 1 H), 1.81 (m, 1 H), 1.66 (tt, J1 = 13.7 Hz, J2 = 4.5
Hz, 1 H), 1.44 (m, 1 H), 1.34 (m, 1 H).
MS: m/z = 354 (M)+, 324, 310, 296, 279, 194, 188, 164, 91, 77, 51.
HRMS (ESI): m/z [M + H] calcd for C19H19N2O5: 355.1288; found:
355.1265.
13C NMR (100 MHz, CDCl3): d = 144.5 (C), 140.8 (C), 133.5 (C),
130.9 (CH), 129.4 (CH), 129.1 (CH), 128.8 (CH), 120.7 (C), 117.8
(CH), 114.2 (CH), 74.4 (CH), 60.6 (CH2), 54.3 (CH), 38.9 (CH),
24.1 (CH2), 21.9 (CH2).
MS: m/z = 301 (M + 2)+, 299 (M)+, 268, 266, 240, 216, 188, 130,
115, 89, 77, 65, 51.
rac-(4aS,5S,10bS)-5-(1,3-Benzodioxol-5-yl)-3,4,4a,5,6,10b-
hexahydro-2H-pyrano[3,2-c]quinoline (5i)15,48
IR (film): 3380, 2925, 1732, 1480, 1333, 1269, 1036, 737 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.41 (dt, J1 = 7.3 Hz, J2 = 1.0 Hz,
1 H), 7.09 (dddd, J1 = 8.1 Hz, J2 = 7.3 Hz, J3 = 1.5 Hz, J4 = 0.8 Hz,
1 H), 6.92 (d, J = 1.8 Hz, 1 H), 6.88 (ddd, J1 = 8.1, J2 = 1.8 Hz,
J3 = 0.7 Hz, 1 H), 6.81 (d, J = 8.1 Hz, 1 H), 6.79 (td, J1 = 7.3 Hz,
J2 = 1.0 Hz, 1 H), 6.58 (dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 5.70 (m,
2 H), 5.30 (d, J = 5.6 Hz, 1 H), 4.60 (d, J = 2.5 Hz, 1 H), 3.59 (m, 1
H), 3.42 (td, J1 = 11.4 Hz, J2 = 2.5 Hz, 1 H), 2.11 (m, 1 H), 1.43–
1.48 (m, 3 H), 1.36 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 147.7 (C), 146.8 (C), 145.1 (C),
135.1 (C), 128.1 (CH), 127.6 (CH), 119.9 (C), 119.8 (CH), 118.4
(CH), 114.4 (CH), 108.1 (CH), 107.4 (CH), 101.1 (CH2), 72.7 (CH),
60.7 (CH2), 59.1 (CH), 39.1 (CH), 25.4 (CH2), 18.1 (CH2).
rac-(4aS,5S,10bS)-5-(3-Chlorophenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (5k)
IR (film): 3314, 2941, 2865, 1607, 1476, 1264, 1071, 737 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.40–7.44 (m, 2 H), 7.29 (m, 3 H),
7.10 (dddd, J1 = 8.1 Hz, J2 = 7.3 Hz, J3 = 1.5 Hz, J4 = 0.7 Hz, 1 H),
6.81 (td, J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 6.61 (dd, J1 = 8.1 Hz,
J2 = 1.0 Hz, 1 H), 5.31 (d, J = 5.6 Hz, 1 H), 4.65 (d, J = 2.5 Hz, 1
H), 3.83 (NH, 1 H), 3.59 (m, 1 H), 3.42 (td, J1 = 11.4 Hz, J2 = 2.5
Hz, 1 H), 2.15 (m, 1 H), 1.42–1.56 (m, 3 H), 1.27 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 144.8 (C), 143.3 (C), 134.4 (C),
129.7 (CH), 128.1 (CH), 127.7 (CH), 127.6 (CH), 126.9 (CH),
125.0 (CH), 119.9 (C), 118.6 (CH), 114.6 (CH), 72.6 (CH), 60.6
(CH2), 58.9 (CH), 38.8 (CH), 25.3 (CH2), 17.9 (CH2).
MS: m/z = 309 (M)+, 279, 265, 225, 233, 218, 188, 121, 91, 77, 51.
rac-(4aS,5R,10bS)-5-(1,3-Benzodioxol-5-yl)-3,4,4a,5,6,10b-
hexahydro-2H-pyrano[3,2-c]quinoline (6i)15,48
IR (film): 3375, 2930, 1729, 1479, 1331, 1271, 1036, 737 cm–1.
MS: m/z = 301 (M + 2)+, 299 (M)+, 268, 266, 254, 240, 217, 144,
1H NMR (400 MHz, CDCl3): d = 7.21 (dd, J1 = 7.3 Hz, J2 = 1.5 Hz,
1 H), 7.09 (ddd, J1 = 8.1 Hz, J2 = 7.3 Hz, J3 = 1.5 Hz, 1 H), 6.93 (d,
J = 1.6 Hz, 1 H), 6.87 (dd, J1 = 7.8 Hz, J2 = 1.6 Hz, 1 H), 6.79 (d,
J = 7.8 Hz, 1 H), 6.70 (td, J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 6.52 (dd,
J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 5.97 (s, 2 H), 4.64 (d, J = 11.2 Hz, 1
H), 4.38 (d, J = 2.8 Hz, 1 H), 4.10 (ddt, J1 = 11.4 Hz, J2 = 4.3 Hz,
J3 = J4 = 2.3 Hz, 1 H), 3.72 (td, J1 = 11.4 Hz, J2 = 2.5 Hz, 1 H), 2.01
(m, 1 H), 1.81 (tdt, J1 = 13.4 Hz, J2 = 11.9 Hz, J3 = 4.3 Hz, 1 H),
1.66 (tt, J1 = 13.6 Hz, J2 = 4.6 Hz, 1 H), 1.52 (m, 1 H), 1.34 (m, 1
H).
13C NMR (100 MHz, CDCl3): d = 148.0 (C), 147.2 (C), 144.7 (C),
136.1 (C), 130.9 (CH), 129.4 (CH), 121.3 (CH), 120.7 (C), 117.6
(CH), 114.2 (CH), 108.1 (CH), 107.7 (CH), 74.6 (CH), 68.7 (CH2),
54.5 (CH), 38.9 (CH), 24.1 (CH2), 21.9 (CH2).
130, 115, 102, 89, 77, 63, 51.
HRMS (ESI): m/z [M + H] calcd for C18H19ClNO: 300.1149; found:
300.1125.
rac-(4aS,5R,10bS)-5-(3-Chlorophenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (6k)
IR (film): 3356, 2925, 2839, 1609, 1490, 1368, 1260, 1053, 749
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.42 (s, 1 H), 7.29 (m, 3 H), 7.21
(dd, J1 = 7.3 Hz, J2 = 1.5 Hz, 1 H), 7.09 (ddd, J1 = 8.1 Hz, J2 = 7.3
Hz, J3 = 1.5 Hz, 1 H), 6.71 (td, J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 6.52
(dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 4.67 (d, J = 10.6 Hz, 1 H), 4.37
(d, J = 2.8 Hz, 1 H), 4.08 (m, 1 H), 3.71 (td, J1 = 11.4 Hz, J2 = 2.5
Synthesis 2008, No. 16, 2527–2536 © Thieme Stuttgart · New York

2534
L. C. da Silva-Filho et al.
PAPER
Hz, 1 H), 2.04 (m, 1 H), 1.81 (tdt, J1 = 13.1 Hz, J2 = 11.6 Hz,
J3 = 4.3 Hz, 1 H), 1.66 (tt, J1 = 13.1 Hz, J2 = 4.5 Hz, 1 H), 1.46 (m,
1 H), 1.36 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 144.5 (C), 144.4 (C), 134.5 (C),
130.9 (CH), 129.9 (CH), 129.4 (CH), 128.1 (CH), 127.8 (CH),
126.1 (CH), 120.6 (C), 117.7 (CH), 114.2 (CH), 74.3 (CH), 68.5
(CH2), 54.5 (CH), 38.9 (CH), 24.1 (CH2), 22.0 (CH2).
(CH), 113.7 (CH), 72.8 (CH), 60.7 (CH2), 58.8 (CH3), 55.3 (CH),
39.0 (CH), 25.4 (CH2), 18.0 (CH2).
MS: m/z = 295 (M)+, 276, 262, 248, 218, 204, 191, 130, 109, 89, 77,
63.
rac-(4aS,5R,10bS)-5-(4-Methoxyphenyl)-3,4,4a,5,6,10b-hexa-
hydro-2H-pyrano[3,2-c]quinoline (6m)15,47
IR (film): 3384, 2939, 2853, 1610, 1513, 1249, 1174, 1080, 750
cm–1.
MS: m/z = 301 (M + 2)+, 299 (M)+, 254, 240, 228, 144, 130, 115,
102, 89, 77, 65, 51.
1H NMR (400 MHz, CDCl3): d = 7.36 (d, J = 8.8 Hz, 2 H), 7.24 (dd,
J1 = 7.3 Hz, J2 = 1.5 Hz, 1 H), 7.11 (ddd, J1 = 8.1 Hz, J2 = 7.3 Hz,
J3 = 1.5 Hz, 1 H), 6.93 (d, J = 8.8 Hz, 2 H), 6.72 (td, J1 = 7.3 Hz,
J2 = 1.3 Hz, 1 H), 6.55 (dd, J1 = 8.1 Hz, J2 = 1.3 Hz, 1 H), 4.70 (d,
J = 11.1 Hz, 1 H), 4.41 (d, J = 2.8 Hz, 1 H), 4.12 (m, 1 H), 3.84 (s,
3 H), 3.74 (td, J1 = 11.6 Hz, J2 = 2.5 Hz, 1 H), 2.08 (m, 1 H), 1.85
(m, 1 H), 1.67 (tt, J1 = 13.4 Hz, J2 = 4.6 Hz, 1 H), 1.52 (m, 1 H),
1.35 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 159.6 (C), 145.0 (C), 134.5 (C),
131.2 (CH), 129.6 (CH), 129.1 (CH), 121.1 (C), 117.8 (CH), 114.5
(CH), 114.3 (CH), 75.0 (CH), 69.0 (CH2), 55.6 (CH3), 54.4 (CH),
39.2 (CH), 24.4 (CH2), 22.2 (CH2).
HRMS (ESI): m/z [M + H] calcd for C18H19ClNO: 300.1149;
found: 300.1154.
rac-(4aS,5S,10bS)-5-(2-Chlorophenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (5l)47
IR (film): 3363, 2938, 2864, 1605, 1479, 1317, 1089, 928, 754 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.69 (dd, J1 = 7.6 Hz, J2 = 1.8 Hz,
2 H), 7.44 (dt, J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 7.40 (dd, J1 = 7.6 Hz,
J2 = 1.5 Hz, 1 H), 7.30 (td, J1 = 7.6 Hz, J2 = 1.5 Hz, 1 H), 7.24 (td,
J1 = 7.6 Hz, J2 = 1.8 Hz, 1 H), 7.10 (dddd, J1 = 8.1 Hz, J2 = 7.3 Hz,
J3 = 1.5 Hz, J4 = 0.8 Hz, 1 H), 6.82 (td, J1 = 7.3 Hz, J2 = 1.0 Hz, 1
H), 6.62 (dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 5.34 (d, J = 5.6 Hz, 1
H), 5.07 (d, J = 2.3 Hz, 1 H), 3.60 (m, 1 H), 3.43 (td, J1 = 11.5 Hz,
J2 = 2.5 Hz, 1 H), 2.41 (m, 1 H), 1.52–1.60 (m, 2 H), 1.44 (m, 1 H),
1.22 (m, 1 H).
MS: m/z = 295 (M)+, 264, 250, 236, 224, 193, 167, 132, 1121, 91,
77, 65.
rac-(4aS,5S,10bS)-5-(3-Methoxyphenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (5n)
13C NMR (100 MHz, CDCl3): d = 145.2 (C), 138.0 (C), 132.7 (C),
129.9 (CH), 128.5 (CH), 128.3 (CH), 128.0 (CH), 127.7 (CH),
126.5 (CH), 120.2 (C), 118.6 (CH), 114.7 (CH), 72.4 (CH), 60.6
(CH2), 55.7 (CH), 34.8 (CH), 25.4 (CH2), 18.5 (CH2).
IR (film): 3370, 2940, 2853, 1608, 1488, 1265, 1154, 1071, 736
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.42 (dt, J1 = 7.3 Hz, J2 = 1.3 Hz,
1 H), 7.29 (dd, J1 = 8.1 Hz, J2 = 7.6 Hz, 1 H), 7.09 (dddd, J1 = 8.1
Hz, J2 = 7.3 Hz, J3 = 1.5 Hz, J4 = 0.7 Hz, 1 H), 6.99 (d, J = 7.6 Hz,
1 H), 6.98 (s, 1 H), 6.84 (ddd, J1 = 8.2 Hz, J2 = 2.5 Hz, J3 = 1.0 Hz,
1 H), 6.79 (td, J1 = 7.3 Hz, J2 = 1.3 Hz, 1 H), 6.60 (dd, J1 = 8.1 Hz,
J2 = 1.0 Hz, 1 H), 5.32 (d, J = 5.6 Hz, 1 H), 4.66 (d, J = 2.3 Hz, 1
H), 3.82 (s, 3 H), 3.58 (ddt, J1 = 11.6 Hz, J2 = 4.0 Hz, J3 = 1.7 Hz,
1 H), 3.43 (td, J1 = 11.6 Hz, J2 = 2.5 Hz, 1 H), 2.17 (m, 1 H), 1.47–
1.57 (m, 2 H), 1.43 (m, 1 H), 1.33 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 159.6 (C), 145.1 (C), 142.9 (C),
124.4 (CH), 128.8 (CH), 127.6 (CH), 119.9 (C), 119.12 (CH), 118.3
(CH), 114.4 (CH), 112.6 (CH), 112.5 (CH), 72.7 (CH), 60.6 (CH2),
59.3 (CH3), 55.3 (CH), 38.9 (CH), 25.4 (CH2), 18.1 (CH2).
MS: m/z = 301 (M + 2)+, 299 (M)+, 254, 240, 220, 204, 144, 130,
115, 102, 91, 77, 51.
rac-(4aS,5R,10bS)-5-(2-Chlorophenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (6l)47
IR (film): 3362, 2939, 2858, 1609, 1464, 1264, 1083, 928, 736 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.48 (dd, J1 = 7.6 Hz, J2 = 1.8 Hz,
1 H), 7.37 (dd, J1 = 7.6 Hz, J2 = 1.5 Hz, 1 H), 7.22–7.28 (m, 2 H),
7.20 (dd, J1 = 7.3 Hz, J2 = 1.5 Hz, 1 H), 7.10 (ddd, J1 = 7.8 Hz,
J2 = 7.3 Hz, J3 = 1.5 Hz, 1 H), 6.71 (td, J1 = 7.3 Hz, J2 = 1.0 Hz, 1
H), 6.52 (d, J = 7.8 Hz, 1 H), 5.17 (d, J = 9.3 Hz, 1 H), 4.43 (d,
J = 3.3 Hz, 1 H), 4.05 (NH, 1 H), 3.98 (m, 1 H), 3.67 (td, J1 = 11.1
Hz, J2 = 2.7 Hz, 1 H), 2.20 (m, 1 H), 1.92 (m, 1 H), 1.70 (m, 1 H),
1.38–1.51 (m, 2 H).
MS: m/z = 295 (M)+, 264,, 250, 236, 224, 193, 167, 132, 121, 91,
77, 65.
13C NMR (100 MHz, CDCl3): d = 144.4 (C), 140.1 (C), 133.8 (C),
130.3 (CH), 129.5 (CH), 129.2 (CH), 129.0 (CH), 128.7 (CH),
127.3 (CH), 120.1 (C), 117.5 (CH), 113.9 (CH), 73.3 (CH), 67.2
(CH2), 51.4 (CH), 38.0 (CH), 24.3 (CH2), 23.1 (CH2).
HRMS (ESI): m/z [M + H] calcd for C19H22NO2: 296.1645; found:
296.1651.
rac-(4aS,5R,10bS)-5-(3-Methoxyphenyl)-3,4,4a,5,6,10b-hexa-
hydro-2H-pyrano[3,2-c]quinoline (6n)
IR (film): 3373, 2939, 2837, 1609, 1487, 1253, 1155, 1039, 750
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.28 (t, J = 7.6 Hz, 1 H), 7.21 (dd,
J1 = 7.1 Hz, J2 = 1.3 Hz, 1 H), 7.09 (ddd, J1 = 7.8 Hz, J2 = 7.1 Hz,
J3 = 1.5 Hz, 1 H), 7.00 (d, J = 7.1 Hz, 1 H), 6.98 (s, 1 H), 6.86 (ddd,
J1 = 7.6 Hz, J2 = 2.5 Hz, J3 = 0.6 Hz, 1 H), 6.71 (t, J1 = 7.1 Hz, 1 H),
6.53 (d, J = 7.6 Hz, 1 H), 4.68 (d, J = 10.9 Hz, 1 H), 4.38 (d, J = 2.8
Hz, 1 H), 4.10 (ddt, J1 = 11.1 Hz, J2 = 4.5 Hz, J3 = 2.3 Hz, 1 H),
3.80 (s, 3 H), 3.72 (td, J1 = 11.1 Hz, J2 = 2.3 Hz, 1 H), 2.08 (m, 1
H), 1.84 (tdt, J1 = 13.6 Hz, J2 = 11.1 Hz, J3 = 4.5 Hz, 1 H), 1.65 (tt,
J1 = 13.6 Hz, J2 = 4.5 Hz, 1 H), 1.50 (m, 1 H), 1.34 (m, 1 H).
MS: m/z = 301 (M + 2)+, 299 (M)+, 254, 240, 220, 204, 144, 130,
115, 102, 89, 77, 65, 41.
rac-(4aS,5S,10bS)-5-(4-Methoxyphenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (5m)15,47
IR (film): 3375, 2939, 1700, 1607, 1512, 1245, 1176, 1033, 751
cm–1.
1H NMR (400 MHz, CDCl3): d = 7.42 (dt, J1 = 7.3 Hz, J2 = 1.4 Hz,
1 H), 7.33 (d, J = 8.6 Hz, 2 H), 7.09 (dddd, J1 = 8.1 Hz, J2 = 7.3 Hz,
J3 = 1.4 Hz, J4 = 0.8 Hz, 1 H), 6.92 (d, J = 8.6 Hz, 2 H), 6.79 (td,
J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 6.59 (dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1
H), 5.32 (d, J = 5.6 Hz, 1 H), 4.65 (d, J = 2.5 Hz, 1 H), 3.82 (s, 3 H),
3.59 (m, 1 H), 3.43 (td, J1 = 11.4 Hz, J2 = 2.6 Hz, 1 H), 2.12 (m, 1
H), 1.42–1.60 (m, 3 H), 1.34 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 159.9 (C), 144.5 (C), 143.8 (C),
130.9 (CH), 129.6 (CH), 129.4 (CH), 120.7 (C), 120.3 (CH), 117.6
(CH), 114.3 (CH), 113.2 (CH), 74.5 (CH), 68.6 (CH2), 55.2 (CH3),
54.8 (CH), 38.8 (CH), 24.1 (CH2), 22.0 (CH2).
13C NMR (100 MHz, CDCl3): d = 159.0 (C), 143.3 (C), 133.1 (C),
128.0 (CH), 127.9 (CH), 127.6 (CH), 119.9 (C), 118.2 (CH), 114.3
Synthesis 2008, No. 16, 2527–2536 © Thieme Stuttgart · New York

PAPER
Synthesis of Pyrano[3,2-c]quinolines
2535
MS: m/z = 295 (M)+, 264, 250, 236, 224, 210, 193, 167, 144, 130,
115, 92, 77, 65.
rac-(4aS,5R,10bS)-5-(3,4,5-Trimethoxyphenyl)-3,4,4a,5,6,10b-
hexahydro-2H-pyrano[3,2-c]quinoline (6p)
IR (film): 3353, 2938, 2838, 1593, 1495, 1238, 1126, 1083, 749
cm–1.
HRMS (ESI): m/z [M + H] calcd for C19H22NO2: 296.1645; found:
296.1647.
1H NMR (400 MHz, CDCl3): 7.22 (dd, J1 = 7.3 Hz, J2 = 1.5 Hz, 1
H), 7.10 (ddd, J1 = 8.1 Hz, J2 = 7.3 Hz, J3 = 1.5 Hz, 1 H), 6.71 (td,
J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 6.65 (s, 2 H), 6.54 (dd, J1 = 8.1 Hz,
J2 = 1.0 Hz, 1 H), 4.64 (d, J = 10.9 Hz, 1 H), 4.38 (d, J = 2.8 Hz, 1
H), 4.11 (m, 1 H), 3.86 (s, 9 H), 3.73 (td, J1 = 11.6 Hz, J2 = 2.5 Hz,
1 H), 2.04 (m, 1 H), 1.85 (tdt, J1 = 13.4 Hz, J2 = 12.1 Hz, J3 = 4.5
Hz, 1 H), 1.67 (tt, J1 = 13.4 Hz, J2 = 4.8 Hz, 1 H), 1.53 (m, 1 H),
1.36 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 153.7 (C), 145.0 (C), 138.4 (C),
137.8 (C), 131.4 (CH), 129.8 (CH), 121.1 (C), 118.0 (CH), 114.6
(CH), 104.9 (CH), 75.0 (CH), 69.0 (CH2), 61.3 (CH3), 56.6 (CH3),
55.5 (CH), 39.4 (CH), 24.5 (CH2), 22.4 (CH2).
rac-(4aS,5S,10bS)-5-(2-Methoxyphenyl)-3,4,4a,5,6,10b-hexahy-
dro-2H-pyrano[3,2-c]quinoline (5o)51
IR (film): 3373, 2937, 2865, 1602, 1488, 1241, 1090, 753 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.55 (dd, J1 = 7.6 Hz, J2 = 1.5 Hz,
1 H), 7.42 (dt, J1 = 7.3 Hz, J2 = 1.0 Hz, 1 H), 7.28 (td. J1 = 8.1 Hz,
J2 = 7.6 Hz, J3 = 1.5 Hz, 1 H), 7.08 (dddd, J1 = 8.1 Hz, J2 = 7.3 Hz,
J3 = 1.5 Hz, J4 = 0.8 Hz, 1 H), 6.98 (td, J1 = 7.6 Hz, J2 = 1.0 Hz, 1
H), 6.90 (dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 6.78 (td, J1 = 7.3 Hz,
J2 = 1.0 Hz, 1 H), 6.60 (dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 5.32 (d,
J = 5.6 Hz, 1 H), 5.03 (d, J = 2.3 Hz, 1 H), 3.82 (s, 3 H), 3.58 (m, 1
H), 3.43 (td, J1 = 11.6 Hz, J2 = 2.4 Hz, 1 H), 2.33 (m, 1 H), 1.48–
1.58 (m, 3 H), 1.42 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 156.4 (C), 145.7 (C), 129.1 (C),
128.1 (CH), 127.9 (CH), 127.7 (CH), 127.1 (C), 120.2 (CH), 120.1
(CH), 118.0 (CH), 114.5 (CH), 110.3 (CH), 72.8 (CH), 60.7 (CH2),
55.3 (CH3), 52.6 (CH), 35.2 (CH), 25.6 (CH2), 18.5 (CH2).
MS: m/z = 355 (M)+, 325, 311, 297, 279, 264, 188, 167, 91, 77, 51.
HRMS (ESI): m/z [M + H] calcd for C21H26NO4: 356.1856; found:
296.1852.
MS: m/z = 295 (M)+, 264, 250, 236, 224, 209, 188, 130, 115, 91, 77,
65.
Acknowledgment
The authors thank the Fundação de Amparo à Pesquisa do Estado
de São Paulo (FAPESP), the Conselho Nacional de Desenvolvi-
mento Científico e Tecnológico (CNPq), the Coordenadoria de
Aperfeiçoamento de Pessoal do Nível Superior (CAPES) and the
Financiadora de Estudos e Projetos (FINEP) for financial support.
We also thank CBMM - Companhia Brasileira de Mineralogia e
Mineração for NbCl5 samples.
rac-(4aS,5R,10bS)-5-(2-Methoxyphenyl)-3,4,4a,5,6,10b-hexa-
hydro-2H-pyrano[3,2-c]quinoline (6o)51
IR (film): 3362, 2938, 2837, 1609, 1491, 1244, 1079, 755 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.44 (dd, H, J1 = 7.6 Hz, J2 = 1.5
Hz, 1 H), 7.25 (ddd, J1 = 8.1 Hz, J2 = 7.6 Hz, J3 = 1.5 Hz, 1 H), 7.23
(dd, J1 = 7.3 Hz, J2 = 1.5 Hz, 1 H), 7.07 (ddd, J1 = 8.1 Hz, J2 = 7.3
Hz, J3 = 1.5 Hz, 1 H), 6.96 (td, J1 = 7.6 Hz, J2 = 0.8 Hz, 1 H), 7.84
(dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 6.68 (td, J1 = 7.3 Hz, J2 = 1.0 Hz,
1 H), 6.51 (dd, J1 = 8.1 Hz, J2 = 1.0 Hz, 1 H), 5.19 (d, J = 10.1 Hz,
1 H), 4.41 (d, J = 3.0 Hz, 1 H), 4.01 (m, 1 H), 3.84 (s, 3 H), 3.68 (td,
J1 = 11.1 Hz, J2 = 2.8 Hz, 1 H), 2.13 (m, 1 H), 1.92 (m, 1 H), 1.65
(tt, J1 = 13.6 Hz, J2 = 4.1 Hz, 1 H), 1.49 (dqd, J1 = 13.6 Hz, J2 = 4.1
Hz, J3 = 1.3 Hz, 1 H), 1.35 (m, 1 H).
13C NMR (100 MHz, CDCl3): d = 157.5 (C), 145.1 (C), 130.9 (C),
130.5 (CH), 129.1 (CH), 128.4 (CH), 128.1 (CH), 120.9 (CH),
120.4 (C), 117.1 (CH), 114.0 (CH), 110.4 (CH), 74.1 (CH), 67.7
(CH2), 53.3 (CH3), 47.6 (CH), 38.2 (CH), 24.5 (CH2), 22.7 (CH2).
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