A concise synthesis of pyrrolo- and pyrrolidino[1,2-a]quinolin-1-ones via Diels-Alder reactions of N-acyliminium cations with olefins

Article abstract of DOI:10.1055/s-2006-942372

A concise and efficient synthesis of pyrrolo- and pyrrolidino[1,2-a] quinolin-1-ones has been developed. New members of this family can thus be generated via Diels-Alder reactions of olefins with N-acyliminium cations produced, in the presence of BF₃

Full text of DOI:10.1055/s-2006-942372

PAPER
2053
A Concise Synthesis of Pyrrolo- and Pyrrolidino[1,2-a]quinolin-1-ones via
Diels–Alder Reactions of N-Acyliminium Cations with Olefins
Diels–Alder
Reactions
o
e
f
N
-Acylim
i
inium Cation
Z
s
w
ith Olefins hang,* Limin Huang, Junpu Wang
State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P. R. of China
Fax +86(931)8625657; E-mail: zhangwei6275@lzu.edu.cn
Received 12 December 2005; revised 20 January 2006
N-Acyliminium cations are known to be important inter-
mediates for the construction of nitrogen-containing
heterocycles,7 and intramolecular cyclization of N-acyl-
iminium cations have been extensively used in the synthe-
Abstract: A concise and efficient synthesis of pyrrolo- and pyrroli-
dino[1,2-a]quinolin-1-ones has been developed. New members of
this family can thus be generated via Diels–Alder reactions of ole-
fins with N-acyliminium cations produced, in the presence of
BF3·Et2O, from 5-hydroxy-1-arylpyrrol-2-ones and 5-hydroxy-1- sis of natural alkaloid products.7,8 However,
arylpyrrolidin-2-ones in moderate to high yields at ambient temper-
ature.
investigations on intermolecular cycloadditions are rare
and no report has been found dealing with the synthesis of
Key Words: N-acyliminium cation, Diels–Alder reaction, alkenes,
5-hydroxy-1-arylpyrrol-2-one, pyrrolo[1,2-a]quinolin-1-one
pyrrolo[1,2-a]quinolinones by the intermolecular cy-
cloaddition reaction of N-acyliminium cations with ole-
fins. In connection with our studies on the synthesis of
biologically active heterocycles,10 we wish to report here-
Pyrrolo- and pyrrolidino[1,2-a]quinolinone derivatives in a concise and efficient synthesis of pyrrolo- and pyrro-
are endowed with an array of biological activities,1–4 such lidino-[1,2-a]quinolin-1-ones via intermolecular Diels–
as antileukemic, antiallergic and antibacterial activities. Alder reactions of N-acyliminium cations with olefins.
Pyrrolo[1,2-a]quinolinones are also used as versatile key The cations used in this study were generated from 5-hy-
intermediates in the synthesis of alkaloid gephyrotoxins.5 droxy-1-arylpyrrol-1-ones (1a–d) or 5-hydroxy-1-
Therefore, a variety of synthetic methodologies for the arylpyrrolidin-1-ones (2a–c) in the presence of BF3·OEt2,
preparation of pyrrolo[1,2-a]quinolinone derivatives have while the olefins chosen – styrene (3a), a-methylstyrene
been developed. Such approaches include Lewis acid cat- (3b), anethole (3c) and indene (3d) – indicate the scope of
alyzed ring-opening and rearrangement of aryl ep- the reaction (Scheme 1 and Scheme 2). The conciseness
oxyazides;6a Reformatsky reaction between diethyl comes about through the ready availability of the precur-
bromomalonate and N-arylpyrrolidine-2-thiones and cy- sor anilines, which can be easily converted to cyclic imi-
clization of the resulting enaminone;3a intramolecular des and then selectively reduced with sodium borohydride
Friedel–Crafts reaction of pyrrolidin-2-one-5-acetyl to give the starting materials (1a–d) and (2a–d).
chlorides;4 condensation of anilines with diethyl 3-oxo-
The reactions between 1a–d or 2a–d with 3a–d were
completely regioselective and stereoselective, giving only
the endo and exo isomers depicted in Scheme 1 and
hexanedioate followed by cyclization of the resulting
b-anilinoacrylate;6b ring-opening of diphenylcycloprope-
none and subsequent [3+2] cycloaddition reaction with
Scheme 2. Moreover, the reactions were quick and effi-
cyclic amidines6c and photochemical cyclization of 2-azi-
cient, affording the products 4a–l or 5a–j in high yields
(Tables 1 and 2). The endo and exo isomers could be sep-
dophenylethylfurancarboxylate, followed by acid-cata-
lyzed hydrolysis.6d Most of these methods, however,
arated and their configurations assigned by 1H, 13C and 2D
require multi-step reactions and are often unsatisfactory
NMR spectroscopy with confirmation by NOESY corre-
both in yield and generality.
lation (Figure 1).
O
O
O
R4
R3
BF3⋅OEt2
R1
R2
N
R
N
R
N
R
+
+
CH2Cl2
r.t.
H
R2
H
OH
R3
R4
R1
R1
R4
R3
R2
1a–d
exo-4a–l
endo-4a–l
3a–d
Scheme 1
SYNTHESIS 2006, No. 12, pp 2053–2063
x
x.
x
x
.
2
0
0
6
Advanced online publication: 05.05.2006
DOI: 10.1055/s-2006-942372; Art ID: F21005SS
© Georg Thieme Verlag Stuttgart · New York

2054
W. Zhang et al.
PAPER
Table 1 Reaction of 5-Hydroxy-1-arylpyrrol-1-ones (1a–d) with Olefins (3a–d)
Entry
Substrates
Time
(min)
Product
Yield (%)a
endo:exo
R
R1
H
R2
R3
Ph
Ph
Bn
R4
H
1
2
1a
1a
1a
1a
1b
1b
1b
1c
1c
1c
1d
1d
H
3a
3b
3c
3d
3a
3c
3d
3b
3c
3d
3a
3c
H
30
30
30
30
30
30
30
30
30
30
30
30
4a
4b
4c
4d
4e
4f
47:43
50:43
50:35
52:35
51:40
53:33
54:26
52:43
61:23
58:31
48:42
45:38
H
H
H
Me
H
3
H
Me
H
H
4
H
-CH2C6H4-
H
5
Me
Me
Me
OMe
OMe
OMe
Cl
H
H
Ph
H
6
Me
H
H
Bn
H
7
-CH2C6H4-
H
4g
4h
4i
8
H
H
Ph
Me
H
9
Me
H
H
Bn
10
11
12
-CH2C6H4-
H
4j
H
H
H
Ph
H
4k
4l
Cl
Me
Bn
H
a Isolated yields of endo- and exo-isomers
For example, the cis-configuration at C-3a and C-5 in C-5 was assigned by the large vicinal coupling constants
endo-4a was assigned by the large vicinal coupling con- J3a–4ax = 10.5 Hz, J5–4ax = 12.0 Hz and strong NOESY cor-
stants J3a–4ax = 12.3 Hz and J5–4ax = 12.3 Hz since these in- relation between H-3a and H-5, similar to that of endo-4a.
dicated that the C-4 axial proton had an anti axial-axial While in exo-4c, the apparent singlet for H-5 at d = 4.07
orientation to both the protons at C-3 and C-5. The trans- ppm and the double doublet with smaller coupling con-
configuration of C-3a and C-5 in exo-4a, on the other stants J3a–4 = 6.0, 1.8 Hz for H-3a at 4.43 ppm indicated
hand, was characterized by a similarly large vicinal cou- there was no anti axial-axial orientation of adjacent pro-
pling constant J3a–4ax = 12.9 Hz, indicative of an axial ori- tons present at C-3a, C-4 and C-5. The lack of any NOE-
entation of H-3a, but with a significantly smaller vicinal SY correlation between C-3a and C-5 supported this cis-
coupling constant between H-5 and H-4 of J4–5 = 5.4 Hz, assignment, as did the observed NOESY correlation be-
typical of a gauche conformation. These assignments tween C-3a and C-4 and the correlation between the C-5
were confirmed by NOESY correlation as depicted in proton and the protons of methyl group at C-4 (Figure 1).
Figure 1.
For the reaction of 2a–d with 3a–d, similar patterns of
In the reactions of 1a–d with 3c, though three stereoiso- products were obtained to those from reactions of 1a–d
mers were produced, two predominated. The two major with 3a–d. For example, the reactions of 2a with 3b af-
products seemed to be derived from the exo- and endo- forded a mixture of endo-5a and exo-5a. In the exo-5a, the
Diels–Alder reaction of 3c with the N-acyliminium cation. axial orientation of H-3a could be deduced from the triplet
The configurations of these products, for example endo- of H-4ax and the large vicinal coupling constant J3a–4ax
=
1
4c and exo-4c, were also assigned by H and 2D NMR 2.6 Hz indicative of the anti axial-axial orientation of H-
spectroscopy and confirmed by NOESY correlation 3a with H-4ax. A strong NOESY correlation between H-3a
(Figure 1). In endo-4c, the cis configuration of C-3a and and H-2¢ of phenyl at C-5 and no NOESY correlation be-
O
O
O
R4
R3
BF3⋅OEt2
R1
R2
N
R
N
R
N
R
+
+
CH2Cl2
H
R2
H
OH
R3
r.t.
R4
R1
R1
R4
R3
endo-5a–k
R2
exo-5a–k
2a–d
3a–d
Scheme 2
Synthesis 2006, No. 12, 2053–2063 © Thieme Stuttgart · New York

PAPER
Diels–Alder Reactions of N-Acyliminium Cations with Olefins
2055
Table 2 Reaction of 5-Hydroxy-1-arylpyrrolidin-1-ones (2a–d) with Olefins (3a–d)
Entry
Substrates
Time
(min)
Product
Yield (%)a
endo:exo
R
R1
H
R2
R3
Ph
R4
Me
H
1
2
2a
2a
2b
2b
2b
2b
2c
2c
2d
2d
2d
H
3b
3d
3a
3b
3c
3d
3b
3c
3a
3c
3d
H
30
30
30
30
30
30
30
30
30
30
30
5a
5b
5c
5d
5e
5f
51:42
57:30
43:46
57:34
51:32
58:25
57:32
52:28
45:38
47:36
54:32
H
H
-CH2C6H4-
3
Me
Me
Me
Me
OMe
OMe
Cl
H
H
Ph
Ph
Bn
H
4
H
H
Me
H
5
Me
H
H
6
-CH2C6H4-
H
7
H
H
Ph
Bn
Ph
Bn
Me
H
5g
5h
5i
8
Me
H
H
9
H
H
10
11
Cl
Me
H
H
H
5j
Cl
-CH2C6H4-
H
5k
a Isolated yields of endo- and exo-isomers
tween H-3a and protons of methyl at C-5 indicated that the certain that the Diels–Alder reaction of N-acyliminium
phenyl group was positioned in an axial orientation. The cation with olefins is not a concerted, but a two-step addi-
cis-configuration of endo-5a could only be assigned by tion reaction. A plausible mechanism is depicted in
NOESY correlation as depicted in Figure 1.
Scheme 3. The initial dehydroxylation produces an
N-acyliminium cation followed by electrophilic attack on
the olefin, leading to a carbocation. Subsequent intramo-
lecular Friedel–Crafts reaction of the cation then affords
the 1,3a,4,5-tetrahydropyrrolo[1,2-a]quinolin-1-one.
As carbocation intermediates are involved in the forma-
tion of 1,3a,4,5-tetrahydropyrrolo[1,2-a]quinolin-1-ones
and 1,2,3,3a,4,5-hexahydro[1,2-a]quinolin-1-ones, and
considering that three steroisomers were observed in the
reaction of N-acyliminium cation with anethole (3c), it is
O
O
O
H
O
H
CH3
H
N
H
N
H
N
H
N
H
H
H
H
H
H3C
H
H
H
H
H
H
H
H
OCH3
H
H
H
OCH3
exo-4c
exo-4a
endo-4c
endo-4a
O
O
O
H
H
H
N
H
H
H
H
N
H
N
N
H
H
H
H
H
O
H
H
CH3
H
H
H
H
H
CH3
H
endo-5b
exo-5a
exo-5b
endo-5a
Figure 1 NOESY correlations of the endo-4a, exo-4a, endo-4c, exo-4c, endo-5a, exo-5a, endo-5b and exo-5b.
Synthesis 2006, No. 12, 2053–2063 © Thieme Stuttgart · New York

2056
W. Zhang et al.
PAPER
O
Pyrrolo[1,2-a]quinolin-1-ones and Pyrrolidino[1,2-a]quinolin-
1-ones; General procedure
BF3⋅OEt2
+
3a
1a
N
To a solution of 5-hydroxy-1-arylpyrrol-2-one (1a–d) or 5-hy-
droxy-1-arylpyrrolidin-2-one 2a–d (2.0 mmol) and the olefin (2.5
mmol) in anhyd CH2Cl2 (50 mL) was added BF3·OEt2 (2.1 mmol)
in one portion, at r.t., with stirring. The reaction was stirred for 0.5
h then quenched with aq Na2CO3 (0.1 M, 50 mL). The organic phase
was taken, washed with H2O (2 × 50 mL) and dried over Na2SO4.
The solvent was removed under reduced pressure and the residue
was purified either by column chromatography (CHCl3–hexane,
1:2) or by repeated preparative thin plate chromatography. Recrys-
tallization from ethanol gave the products 3a–l and 4a–k as summa-
rized in Tables 1 and 2.
O
N
O
+
+
N
Ph
Ph
4a
endo-1,3a,4,5-Tetrahydro-5-phenylpyrrolo[1,2-a]quinolin-1-
one (endo-4a)
Scheme 3
Colorless needles; mp 155–157 °C.
1H NMR (CDCl3): d = 1.69 (q, J = 12.9 Hz, 1 H, H-4), 2.58 (dt,
J = 12.9, 3.3 Hz, 1 H, H-4), 4.23 (dd, J = 12.6, 5.7 Hz, 1 H, H-3a),
4.52 (d, J = 11.7 Hz, 1 H, H-5), 6.33 (d, J = 5.3 Hz, 1 H, H-2), 6.80
(d, J = 7.8 Hz, 1 H, H-8), 6.95 (t, J = 7.5 Hz, 1 H, H-7), 7.03 (d,
J = 6.9 Hz, 1 H, H-6), 7.17 (d, J = 7.2 Hz, 2 H, H-2¢), 7.27–7.33 (m,
In summery, a concise and efficient approach to the syn-
thesis of a variety of pyrrolo[1,2-a]quinolin-1-ones and
pyrrolidino[1,2-a]quinolin-1-ones has been developed.
To our knowledge, this is the first reported synthesis of
these compounds via Diels–Alder reaction of N-acylimin- 4 H, H-3¢, H-4¢, H-3), 8.39 (d, J = 8.1 Hz, 1 H, H-1).
13C NMR (CDCl3): d = 37.1 (C-4), 45.1 (C-5), 61.5 (C-3a), 119.5
(C-9), 123.6 (C-7), 126.7 (C-5a), 127.0 (C-2), 127.3 (C-4¢), 128.5
(C-8), 128.6 (2C, C-2¢), 128.8 (2C, C-3¢), 129.7 (C-6), 136.0 (C-9a),
144.5 (C-1¢), 146.3 (C-3), 168.7 (C-1).
MS (EI): m/z (%) = 261 (100) [M+], 232 (40), 217 (9), 206 (14), 182
(69), 165 (20), 156 (74), 128 (23).
ium cations with olefins. Extension of this strategy to oth-
er substrates is under the way in this laboratory.
All the reactions were monitored by TLC over silica gel coated TLC
plates. Silica gel 230–400 mesh was used for column chromatogra-
phy. EI-MS were recorded with a HP 5988 A mass spectrometer. 1H
and 13C NMR spectra were recorded on a Bruker AM-400 NMR or
a Bruker DRX-300 NMR spectrometers in CDCl3 with TMS as an
internal standard. Melting points were determined on a Yanagimoto
melting point apparatus and are uncorrected. Elementary analyses
were carried out on a PERKIN-ELMER 2400 II analyzer. All sol-
vents were dried and distilled before use.
Anal. Calcd for C18H15NO: C, 82.73; H, 5.79; N 5.36. Found: C,
82.68; H, 5.82; N 5.32.
exo-1,3a,4,5-Tetrahydro-5-phenylpyrrolo[1,2-a]quinolin-1-one
(exo-4a)
Dense oil.
1H NMR (CDCl3): d = 1.83 (dt, J = 12.9, 5.7 Hz, 1 H, H-4ax), 2.28
(d, J = 12.9 Hz, 1 H, H-4eq), 4.21 (d, J = 12.3 Hz, 1 H, H-3a), 4.53
(d, J = 5.1 Hz, 1 H, H-5), 6.19 (dd, J = 6.0, 1.5 Hz, 1 H, H-3), 6.94–
7.10 (m, 4 H), 7.20–7.30 (m, 5 H), 8.52 (d, 1 H, J = 8.1 Hz, H-9).
13C NMR (CDCl3): d = 34.8 (C-4), 42.4 (C-5), 56.2 (C-3a), 119.0
(C-9), 123.4 (C-7), 125.9 (C-5a), 126.3 (C-4¢), 127.3 (C-2), 128.1
(2C, C-2¢), 128.3 (2C, C-3¢), 128.4 (C-8), 130.1 (C-6), 136.3 (C-9a),
145.1 (C-1¢), 147.0 (C-3), 168.7 (C-1).
5-Hydroxy-1-arylpyrrol-2-ones (1a–d) and 5-Hydroxy-1-aryl-
pyrrolidin-2-ones (2a–b,2d); General Procedure11a
Method A: Sodium borohydride (0.022 mol) was added in portions
to a stirred mixture of 1-arylpyrrole-2,5-dione (0.02 mol) or
1-arylpyrrolidine-2,5-dione (0.02 mol) and CeCl3·6H2O (0.022
mol) in anhyd MeOH (100 mL) at 0 °C. After the CeCl3·6H2O was
all dissolved and no imides were detected, the mixture was poured
into CH2Cl2 (50 mL) and H2O (100 mL) was added. The organic
phase was washed with H2O (2 × 50 mL) and dried over Na2SO4.
The solvent was removed at reduced pressure to give the products
1a–d and 2a–b, 2d.
MS (EI): m/z (%) = 261 (100) [M+], 232 (64), 217 (13), 206 (18),
184 (38), 170 (23), 156 (30), 128 (27).
Anal. Calcd for C18H15NO: C, 82.73; H, 5.79; N, 5.36. Found: C,
82.66; H, 5.85; N, 5.28.
5-Hydroxy-1-arylpyrrolidin-2-ones (2a–d); General
Procedure11b
endo-1,3a,4,5-Tetrahydro-5-methyl-5-phenylpyrrolo[1,2-
a]quinolin-1-one (endo-4b)
Colorless needles; mp 188–189 °C.
Method B: Sodium borohydride (9.0 mmol) was added in portions
to a stirred solution of 1-arylpyrrolidine-2,5-diones (3.0 mmol) in
anhyd EtOH (250 mL) at –21 °C over 5 h. At regular intervals (15
min), 2–3 drops of HCl (2 N in EtOH) was added until the solution
reached pH 3. The mixture was then poured into H2O (250 mL) and
extracted with CHCl3 (2 × 50 mL). The organic phase was then tak-
en, washed with H2O (2 × 50 mL) and dried over Na2SO4. The sol-
vent was removed at reduced pressure and the residue was purified
by column chromatography (CHCl3–acetone, 4:1) to give the 5-
ethoxy-1-arylpyrrolidin-2-ones. A solution of 5-ethoxy-1-arylpyr-
rolidin-2-one (5 mmol) in a mixture of dioxane and H2O (70 mL,
5:2) with silica-alumina catalyst (10 mmol) was refluxed for 5 h
then poured into H2O (100 mL). The mixture was extracted with
CH2Cl2 (2 × 50 mL) and the organic phase was washed with H2O
(2 × 50 mL) and dried over Na2SO4. Removal of solvent afforded
the product 2a–d.
1H NMR (CDCl3): d = 1.77 (t, J = 12.9 Hz, 1 H, H-4ax), 1.80 (s, 3 H,
CH3), 2.22 (dd, J = 12.9, 2.4 Hz, 1 H, H-4eq), 4.54 (d, J = 12.3 Hz,
1 H, H-3a), 6.27 (d, J = 6.0 Hz, 1 H, H-2), 6.77 (d, J = 8.1 Hz, 1 H,
H-6), 6.91 (t, J = 7.8 Hz, 1 H, H-8), 7.11 (d, J = 6.0 Hz, 1 H, H-3),
7.14–7.24 (m, 6 H, Ph, H-7), 8.34 (d, J = 8.4 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 28.5 (CH3), 42.4 (C-5), 44.1 (C-4), 58.4 (C-
3a), 119.6 (C-9), 123.7 (C-7), 125.9 (C-5a), 126.1 (C-4¢), 126.6 (C-
2), 127.0 (2C, C-2¢), 128.1 (2C, C-3¢), 128.5 (C-8), 129.5 (C-6),
134.8 (C-9a), 146.9 (C-1¢), 149.2 (C-3), 168.4 (C-1).
MS(EI) : m/z (%) = 275 (M+, 89), 260 (100), 246 (40), 232 (19), 198
(14), 182 (30).
Synthesis 2006, No. 12, 2053–2063 © Thieme Stuttgart · New York

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Diels–Alder Reactions of N-Acyliminium Cations with Olefins
2057
Anal. Calcd for C19H17NO: C, 82.88; H, 6.22; N, 5.09. Found: C,
82.83; H, 6.25; N, 5.04.
J = 5.7, 1.5 Hz, 1 H, H-2), 6.97–7.19 (m, 4 H), 7.26 (d, J = 9.0 Hz,
1 H), 7.39–7.52 (m, 3 H), 8.18 (d, J = 8.1 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 30.4 (CH2), 41.4 (C-5), 45.5 (C-4), 61.3 (C-
3a), 119.5 (C-9), 124.0 (C-7), 124.5 (CH), 124.7 (CH), 126.1 (C-
5a), 126.7 (CH), 127.2 (CH), 127.9 (CH), 128.6 (CH), 128.9 (C-7),
134.7 (C-9a), 141.4 (C), 145.2 (C), 145.6 (C-3), 168.6 (C-1).
MS (EI): m/z (%) = 273 (18) [M+], 244 (9), 233 (23), 219 (2), 191
(6), 173 (13), 135 (7), 119 (38), 43 (100).
exo-1,3a,4,5-Tetrahydro-5-methyl-5-phenylpyrrolo[1,2-a]quin-
olin-1-one (exo-4b)
Colorless needles; mp 146–147 °C.
1H NMR (CDCl3): d = 1.73 (t, J = 12.9 Hz, 1 H, H-4ax), 1.84 (s, 3 H,
CH3), 2.42 (dd, J = 12.9, 2.4 Hz, 1 H, H-4eq), 4.07 (dd, J = 12.9, 2.4
Hz, 1 H, H-3a), 6.24 (dd, J = 8.7, 1.8 Hz, 1 H, H-2), 6.99 (dd,
J = 7.8, 1.8 Hz, 1 H, H-6), 7.05 (d, J = 8.1 Hz, 2 H, H-2¢), 7.11–
7.30 (m, 5 H), 7.36 (t, J = 8.1 Hz, 1 H, H-7), 8.50 (d, J = 8.1 Hz,
1 H, H-9).
13C NMR (CDCl3): d = 29.9 (CH3), 42.5 (C-5), 43.8 (C-4), 57.8 (C-
3a), 119.5 (C-9), 123.9 (C-7), 126.4 (C-5a), 127.1 (2C, C-2¢), 127.4
(C-4¢), 128.2 (2C, C-3¢), 128.4 (C-2), 128.6 (C-8), 128.9 (C-6),
131.4 (C-3), 135.8 (C-9a), 147.1 (C-1¢), 148.9 (C-3), 169.0 (C-1).
Anal. Calcd for C19H15NO: C, 83.49; H, 5.53; N, 5.12. Found: C,
83.46; H, 5.58; N, 5.09.
exo-5a,5b,8,12b-Tetrahydroindeno[2,3-c]pyrrolo[1,2-a]quino-
lin-8-one (exo-4d)
Colorless needles; mp 137–138 °C.
1H NMR (CDCl3): d = 2.41 (m, 1 H, H-4), 2.93 (d, J = 16.2 Hz,
1 H), 3.27 (dd, J = 16.2, 6.3 Hz, 1 H), 3.73 (d, J = 11.7 Hz, 1 H, H-
3a), 4.41 (d, J = 6.0 Hz, 1 H, H-5), 6.26 (dd, J = 6.0, 1.5 Hz, 1 H, H-
2), 6.02–7.32 (m, 7 H), 7.48 (d, J = 7.5 Hz, 1 H, H-3), 8.36 (d,
J = 8.1 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 34.2 (CH2), 42.0 (C-5), 46.7 (C-4), 60.2 (C-
3a), 119.5 (C-9), 123.4 (C-7), 124.1 (CH), 125.3 (CH), 125.7 (C-
5a), 126.7 (CH), 127.2 (CH), 128.8 (CH), 129.8 (C-6), 134.9 (C-
9a), 139.8 (C), 143.1 (C), 146.2 (C-3), 168.4 (C-1).
MS (EI): m/z (%) = 275 (49) [M+], 260 (20), 246 (6), 232 (26), 203
(12), 198 (12), 182 (100).
Anal. Calcd for C19H17NO: C, 82.88; H, 6.22; N, 5.09. Found: C,
82.82; H, 6.28; N. 5.01.
endo-1,3a,4,5-Tetrahydro-4-methyl-5-(4-methoxyphenyl)pyr-
rolo[1,2-a]quinolin-1-one (endo-4c)
Colorless needles; mp 165–166 °C.
MS (EI): m/z (%) = 273 (24) [M+], 244 (3), 219 (2), 182 (8), 154 (5),
128 (7), 115 (10), 84 (100).
1H NMR (CDCl3): d = 1.07 (d, J = 6.8 Hz, 3 H, CH3), 1.65–1.85 (m,
1 H, H-4), 3.65 (d, J = 12.0 Hz, 1 H, H-5), 3.81 (s, 3 H, OCH3), 4.14
(d, J = 10.5 Hz, 1 H, H-3a), 6.37 (d, J = 6.0 Hz, 1 H, H-2), 6.74 (d,
J = 8.1 Hz, 1 H, H-6), 6.84–7.14 (m, 5 H), 7.24 (t, J = 8.1 Hz, 1 H,
H-7), 7.33 (d, J = 6.0, 2.0 Hz, 1 H, H-3), 8.39 (d, J = 8.7 Hz, 1 H,
H-9).
13C NMR (CDCl3): d = 16.0 (CH3), 40.8 (C-5), 52.1 (C-4), 55.2
(OCH3), 66.6 (C-3a), 114.0 (2C, C-3¢), 119.1 (C-9), 123.5 (C-7),
125.4 (C-5a), 127.0 (C-2), 129.3(C-8), 130.0 (C-6), 130.4 (2C),
135.4 (C-9a), 135.6 (C-1¢), 145.4 (C-3), 158.6 (C-4¢), 168.5 (C-1).
Anal. Calcd for C19H15NO: C, 83.49; H, 5.53; N, 5.12. Found: C,
83.42; H, 5.56; N, 5.07.
endo-1,3a,4,5-Tetrahydro-7-methyl-5-phenylpyrrolo[1,2-
a]quinolin-1-one (endo-4e)
Colorless needles; mp 154–155 °C.
1H NMR (CDCl3): d = 1.64 (q, J = 12.6 Hz, 1 H, H-4), 2.14 (s, 3 H,
CH3), 2.52 (dq, J = 12.6, 5.7, 2.4 Hz, 1 H, H-4), 4.16 (dd, J = 12.3,
5.7 Hz, 1 H, H-3a), 4.44 (d, J = 11.7 Hz, 1 H, H-5), 6.28 (d, J = 5.7
Hz, 1 H, H-3), 6.60 (s, 1 H, H-6), 7.05 (d, J = 8.7 Hz, 1 H, H-8),
7.11–7.17 (m, 3 H), 7.21–7.34 (m, 3 H), 8.26 (d, J = 8.1, 1 H, H-1).
MS (EI): m/z (%) = 305 (49) [M+], 290 (15), 276 (3), 262 (3), 223
(10), 182 (25), 170 (100).
Anal. Calcd for C20H19NO2: C, 78.66; H, 6.27; N, 4.59. Found: C,
78.63; H, 6.32; N, 4.55.
13C NMR (CDCl3): d = 34.6 (C-4), 44.7 (C-5), 60.8 (C-3a), 119.6
(C-9), 126.7 (C-5a), 127.2 (C-2), 127.5 (C-4¢), 129.1 (C-8), 128.4
(2C, C-2¢), 128.7 (2C, C-3¢), 129.3 (C-6), 131.1 (C-7), 133.8 (C-5a),
136.3 (C-9a), 146.1 (C-1¢), 146.5 (C-3), 168.9 (C-1).
MS (EI): m/z (%) = 275 (100) [M+], 246 (47), 232 (14), 220 (8), 196
(38), 182 (11), 170 (5).
exo-1,3a,4,5-Tetrahydro-4-methyl-5-(4-methoxyphenyl)pyrro-
lo[1,2-a]quinolin-1-one (exo-4c)
Colorless needles; mp 131–132 °C.
1H NMR (CDCl3): d = 0.78 (d, J = 7.0 Hz, 3 H, CH3), 2.35–2.44 (m,
1 H, H-4), 3.76 (s, 3 H, OCH3), 4.11 (s, 1 H, H-5), 4.43 (dd, J = 6.0,
1.8 Hz, 1 H, H-3a), 6.27 (dd, J = 6.0, 1.8 Hz, 1 H, H-2), 6.78–6.94
(m, 5 H), 7.04–7.08 (m, 2 H, H-6, H-8), 7.32 (dd, J = 6.0, 2.0 Hz,
1 H, H-3), 8.58 (d, J = 8.1 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 13.4 (CH3), 37.6 (C-5), 50.0 (C-4), 55.3
(OCH3), 59.5 (C-3a), 113.9 (2C), 118.7 (C-9), 123.9 (C-7), 124.9
(C-5a), 127.6 (C-2), 129.3 (C-8), 129.4 (2C), 131.4 (C-6), 136.3 (C-
9a), 137.7 (C-1¢), 146.4 (C-3), 158.3 (C-4¢), 169.8 (C-1).
Anal. Calcd for C19H17NO: C, 82.88; H, 6.22; N, 5.09. Found: C,
82.80; H, 6.28; N, 5.02.
exo-1,3a,4,5-Tetrahydro-7-methyl-5-phenylpyrrolo[1,2-a]quin-
olin-1-one (exo-4e)
Dense oil.
1H NMR (CDCl3) d = 1.88 (td, J = 12.9, 6.0 Hz, 1 H, H-4ax), 2.27
(s, 3 H, CH3), 2.30 (dt, J = 12.9, 3.9, 2.1 Hz, 1 H, H-4eq), 4.25 (dd,
J = 12.3, 2.4 Hz, 1 H, H-3a), 4.43 (d, J = 5.4 Hz, 1 H, H-5), 6.24
(dd, J = 6.0, 1.5 Hz, 1 H, H-3), 6.89 (d, J = 1.2 Hz, 1 H, H-6), 6.98
(dd, J = 6.0, 1.5 Hz, 1 H, H-2), 7.03 (d, J = 8.7 Hz, 2 H), 7.14 (dd,
J = 8.1, 1.8 Hz, 1 H, H-8), 7.22–7.31 (m, 3 H), 8.40 (d, J = 9.0 Hz,
1 H, H-9).
MS (EI): m/z (%) = 305 (47) [M+], 290 (8), 276 (9), 262 (12), 246
(12), 197 (31), 182 (100).
Anal. Calcd for C20H19NO2: C, 78.66; H, 6.27; N, 4.59. Found: C,
78.64; H, 6.33; N, 4.52.
13C NMR (CDCl3): d = 20.8 (CH3), 35.4 (C-4), 42.8 (C-5), 56.6 (C-
3a), 119.2 (C-9), 126.0 (C-8), 126.6 (C-2), 128.5 (4C, C-2¢, C-3¢),
128.9 (C-4¢), 129.0 (C-6), 130.8 (C-7), 133.5 (C-5a), 134.3 (C-9a),
145.6 (C-1¢), 146.9 (C-3), 169.0 (C-1).
MS (EI): m/z (%) = 275 (100) [M+], 246 (42), 232 (11), 220 (11),
196 (50), 182 (26), 170 (8).
endo-5a,5b,8,12b-Tetrahydroindeno[2,3-c]pyrrolo[1,2-a]quino-
lin-8-one (endo-4d)
Colorless needles; mp 184–185 °C.
1H NMR (CDCl3): d = 2.50 (m, 2 H), 3.20–3.30 (m, 1 H, H-4), 4.42
(d, J = 8.1 Hz, 1 H, H-3a), 4.60 (d, J = 1.5 Hz, 1 H, H-5), 6.26 (dd,
Synthesis 2006, No. 12, 2053–2063 © Thieme Stuttgart · New York

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W. Zhang et al.
PAPER
Anal. Calcd for C19H17NO: C, 82.88; H, 6.22; N, 5.09. Found: C,
82.78; H, 6.25; N, 5.05.
J = 6.0, 1.8 Hz, 1 H, H-2), 7.13–7.32 (m, 7 H), 8.26 (d, J = 8.4 Hz,
1 H, H-9).
13C NMR (CDCl3): d = 21.1 (CH3), 34.5 (CH2), 42.4 (C-5), 47.0 (C-
4), 60.4 (C-3a), 119.5 (C-9), 124.3 (C-8), 125.3 (CH), 125.5 (CH),
126.8 (C-2), 127.1 (CH), 128.1 (CH), 129.2 (C-6), 130.3 (C-7),
132.6 (C-5a), 133.0 (C-9a), 140.0 (C), 143.4 (C), 145.8 (C-3), 168.4
(C-1).
MS (EI): m/z (%) = 287 (56) [M+], 272 (11), 258 (26), 244 (12), 232
(26), 217 (21), 196 (86), 115 (42), 43 (100).
endo-1,3a,4,5-Tetrahydro-4,7-dimethyl-5-(4-methoxyphe-
nyl)pyrrolo[1,2-a]quinolin-1-one (endo-4f)
Colorless needles; mp 176–177 °C.
1H NMR (CDCl3): d = 1.03 (d, J = 6.3 Hz, 3 H, CH3), 1.66–1.75 (m,
1 H, H-4), 2.13 (s, 3 H, CH3), 3.58 (d, J = 11.1 Hz, 1 H, H-5), 3.80
(s, 3 H, OCH3), 4.06 (d, 1 H, J = 10.8 Hz, H-3a), 6.33 (dd, J = 6.0,
1.5 Hz, 1 H, H-2), 6.52 (s, 1 H, H-6), 6.85 (d, J = 8.4 Hz, 2 H, H-2¢),
6.89 (d, J = 8.4 Hz, 1 H, H-8), 7.01 (t, J = 8.4 Hz, 2 H, H-3¢), 7.28
(dd, J = 6.0, 1.5 Hz, 1 H, H-3), 8.39 (d, J = 8.0 Hz, 1 H, H-9).
Anal. Calcd for C20H17NO: C, 83.60; H, 5.96; N, 4.87. Found: C,
83.55; H, 6.01; N, 4.83.
13C NMR (CDCl3): d = 16.0 (CH3), 20.8 (CH3), 40.8 (C-5), 52.0 (C-
4), 55.1 (OCH3), 66.5 (C-3a), 113.9 (2C), 118.8 (C-9), 127.6 (C-2),
129.1 (C-8), 129.1 (C-6), 130.3 (2C), 130.9 (C-1¢), 132.9 (C-7),
134.7 (C-5a), 135.3 (C-9a), 145.2 (C-3), 158.4 (C-4¢), 168.2 (C-1).
MS (EI): m/z (%) = 319 (61) [M+], 304 (25), 290 (11), 276 (7), 196
(48), 184 (100).
endo-1,3a,4,5-Tetrahydro-7-methoxy-5-methyl-5-phenylpyrro-
lo[1,2-a]quinolin-1-one (endo-4h)
Colorless needles; mp 180–181 °C.
1H NMR (CDCl3): d = 1.78 (t, J = 13.2 Hz, 1 H, H-4ax), 1.80 (s, 3 H,
CH3), 2.21 (dd, J = 12.9, 2.7 Hz, 1 H, H-4eq), 3.61 (s, 3 H, OCH3),
4.52 (dd, J = 12.9, 2.7 Hz, 1 H, H-3a), 6.27 (d, J = 9.0 Hz, 1 H, H-
8), 6.32 (d, J = 3.0 Hz, 1 H, H-6), 6.79 (dd, J = 6.0, 3.0 Hz, 1 H, H-
3), 7.11 (d, J = 7.5 Hz, 1 H, H-2), 7.15–7.36 (m, 5 H, Ph), 8.26 (d,
J = 9.0 Hz, 1 H, H-9).
Anal. Calcd for C21H21NO2: C, 78.97; H, 6.63; N, 4.39. Found: C,
78.96; H, 6.69; N, 4.34%.
exo-1,3a,4,5-Tetrahydro-4,7-dimethyl-5-(4-methoxyphe-
nyl)pyrrolo[1,2-a]quinolin-1-one (exo-4f)
Colorless needles; mp 141–142 °C.
1H NMR (CDCl3): d = 0.75 (d, J = 7.0 Hz, 3 H, CH3), 2.22 (s, 3 H,
CH3), 2.32–2.37 (m, 1 H, H-4), 3.72 (s, 3 H, OCH3), 4.05 (s, 1 H,
H-5), 4.40 (s, 1 H, H-3a), 6.21 (dd, J = 5.8, 1.5 Hz, 1 H, H-2), 6.79
(d, J = 8.7 Hz, 2 H, H-2¢), 6.86–6.91 (m, 4 H), 7.11 (d, J = 6.0 Hz,
1 H, H-2), 8.48 (d, J = 8.4 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 13.0 (CH3), 20.4 (CH3), 37.3 (C-5), 49.6 (C-
4), 54.8 (OCH3), 59.2 (C-3a), 113.5 (2C), 118.2 (C-9), 124.4 (C-8),
127.9 (C-2), 128.9 (C-6), 129.1 (2C), 131.3 (C-7), 132.8 (C-5a),
133.6 (C-9a), 137.4 (C-1¢), 146.0 (C-3), 157.9 (C-4¢), 169.3 (C-1).
13C NMR (CDCl3): d = 24.1 (CH3), 42.4 (C-5), 44.6 (C-4), 56.3
(OCH3), 58.3 (C-3a), 121.3 (2C, C-9, C-8), 125.0 (C-6), 125.6 (C-
2), 127.3 (2C, C-2¢), 128.4 (C-4¢), 128.8 (2C, C-3¢), 132.1 (C-5a),
133.2 (C-9a), 139.7 (C-1¢), 143.8 (C-3), 151.6(C-7), 167.2 (C-1).
MS (EI): m/z (%) = 305 (75) [M+], 290 (35), 276 (6), 262 (17), 248
(6), 228 (10), 212 (18), 188 (100).
Anal. Calcd for C20H19NO2: C, 78.66; H, 6.27; N, 4.59. Found: C,
78.62; H, 6.28; N, 4.56.
exo-1,3a,4,5-Tetrahydro-7-methoxy-5-methyl-5-phenylpyrro-
lo[1,2-a]quinolin-1-one (exo-4h)
Colorless needles; mp 117–118 °C.
MS (EI): m/z (%) = 319 (15) [M+], 304, 290 (2), 276 (2), 211 (33),
196 (100).
1H NMR (CDCl3): d = 1.69 (t, J = 12.9 Hz, 1 H, H-4ax), 1.82 (s, 3 H,
CH3), 2.40 (d, J = 12.9 Hz, 1 H, H-4eq), 3.76 (s, 3 H, OCH3), 4.03
(d, J = 12.3 Hz, 1 H, H-3a), 6.21 (d, J = 6.0 Hz, 1 H, H-3), 6.79 (d,
J = 8.1 Hz, 1 H, H-6), 6.91–6.96 (m, 2 H, H-8, H-4¢), 7.06 (d,
J = 7.5 Hz, 2 H, H-2¢), 7.16–7.28 (m, 3 H, H-3¢, H-2), 8.43 (d,
J = 8.7 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 29.8 (CH3), 42.7 (C-5), 43.8 (C-4), 55.3 (C-
3a), 57.7 (OCH3), 112.6 (C-8), 113.7 (C-6), 120.5 (C-9), 126.3 (C-
2), 127.0 (2C, C-2¢), 128.2 (2C, C-3¢), 128.6 (C-4¢), 129.6 (C-5a),
132.8 (C-9a), 146.5 (C-3), 148.7 (C-1¢), 155.7 (C-7), 168.6 (C-1).
Anal. Calcd for C21H21NO2: C, 78.97; H, 6.63; N, 4.39. Found: C,
78.92; H, 6.70; N, 4.33.
endo-5a,5b,8,12b-Tetrahydro-11-methylindeno[2,3-c]pyrro-
lo[1,2-a]quinolin-8-one (endo-4g)
Colorless needles; mp 178–179 °C.
1H NMR (CDCl3): d = 2.25 (s, 3 H, CH3), 2.52–2.55 (m, 2 H), 3.30
(dq, J = 1.8, 3.6, 8.1 Hz, 1 H, H-4), 4.43 (d, J = 8.1 Hz, 1 H, H-3a),
4.66 (d, J = 3.6 Hz, 1 H, H-5), 6.29 (dd, J = 6.0, 1.8 Hz, 1 H, H-3),
6.97 (d, J = 8.4 Hz, 1 H, H-8), 7.05–7.20 (m, 4 H), 7.26 (s, 1 H, H-
6), 7.54 (d, J = 7.8 Hz, 1 H), 8.07 (d, J = 8.1 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 21.0 (CH3), 30.6 (CH2), 41.8 (C-5), 45.7 (C-
4), 61.6 (C-3a), 119.6 (C-9), 124.6 (C-7), 124.8 (CH), 124.7 (CH),
126.7 (CH), 127.3 (CH), 127.7 (CH), 129.0 (C-7), 129.36 (C-6),
131.8 (C-5a), 133.6 (C-9a), 141.5 (C), 145.2 (C), 145.4 (C-3), 168.5
(C-1).
MS (EI): m/z (%) = 305 (87) [M+], 290 (34), 276 (10), 262 (29), 248
(10), 228 (20), 212 (100).
Anal. Calcd for C20H19NO2: C, 78.66; H, 6.27; N, 4.59. Found: C,
78.61; H, 6.33; N, 4.52.
endo-1,3a,4,5-Tetrahydro-7-methoxy-4-methyl-5-(4-meth-
oxy)phenylpyrrolo[1,2-a]quinolin-1-one (endo-4i)
Colorless needles; mp 163–164 °C.
1H NMR (CDCl3): d = 1.05 (d, J = 6.6 Hz, 3 H, CH3), 1.62–1.75 (m,
1 H, H-4), 2.17 (d, J = 2.1 Hz, 1 H, H-5), 3.62 (s, 3 H, OCH3), 3.81
(s, 3 H, OCH3), 4.09 (d, J = 2.7 Hz, 1 H, H-6), 6.27 (d, J = 6.0, 1.5
Hz, 1 H, H-6), 6.35 (dd, J = 5.7, 1.8 Hz, 1 H, H-2), 6.80 (dd, J = 9.0,
2.7 Hz, 1 H, H-8), 6.85 (d, J = 8.7 Hz, 2 H, H-2¢), 7.02 (d, J = 8.7
Hz, 2 H, H-3¢), 7.28 (dd, J = 6.0, 1.5 Hz, 1 H, H-3), 8.31 (d, J = 9.0
Hz, 1 H, H-9).
MS (EI): m/z (%) = 287 (77) [M+], 272 (7), 258 (26), 244 (10), 232
(23), 217 (16), 189 (20), 115 (30), 86 (100).
Anal. Calcd for C20H17NO: C, 83.60; H, 5.96; N, 4.87. Found: C,
83.65; H, 6.02; N, 4.85%.
exo-5a,5b,8,12b-Tetrahydro-11-methylindeno[2,3-c]pyrro-
lo[1,2-a]quinolin-8-one (exo-4g)
Colorless needles; mp 144–145 °C.
13C NMR (CDCl3): d = 16.0 (CH3), 40.5 (C-5), 52.1 (C-4), 55.2
(OCH3), 55.3 (OCH3), 66.5 (C-3a), 113.8 (2C, C-2¢), 115.9 (C-9),
116.1 (C-6), 120.3 (C-9), 126.8 (C-2), 128.7 (C-5a), 130.3 (2C, C-
1H NMR (CDCl3): d = 2.43 (s, 3 H, CH3), 2.45–2.53 (m, 1 H, H-4),
2.97 (d, J = 16.5 Hz, 1 H), 3.34 (dd, J = 16.5, 6.3 Hz, 1 H), 3.80 (d,
J = 11.7 Hz, 1 H, H-3a), 4.45 (d, J = 5.7 Hz, 1 H, H-5), 6.30 (dd,
Synthesis 2006, No. 12, 2053–2063 © Thieme Stuttgart · New York

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Diels–Alder Reactions of N-Acyliminium Cations with Olefins
2059
3¢), 133.1 (C-9a), 135.6 (C-1¢), 145.1 (C-3), 155.4 (C-7), 158.6 (C-
4¢), 168.3 (C-1).
MS (EI): m/z (%) = 335 (46) [M+], 320 (9), 306 (6), 292 (8), 276 (2),
endo-1,3a,4,5-Tetrahydro-7-chloro-5-phenylpyrrolo[1,2-
a]quinolin-1-one (endo-4k)
Colorless needles; mp 167–168 °C.
212 (33), 200 (22), 55 (100).
1H NMR (CDCl3): d = 1.65 (q, J = 12.8 Hz, 1 H, H-4), 2.58 (dq,
J = 12.8, 3.0 Hz, 1 H, H-4), 4.17 (dd, J = 12.4, 5.4 Hz, 1 H, H-3a),
4.47 (d, J = 12.4 Hz, 1 H, H-5), 6.31 (d, J = 6.0 Hz, 1 H, H-3), 6.79
(d, J = 1.0 Hz, 1 H, H-6), 7.04–7.35 (m, 7 H), 8.38 (d, J = 8.8 Hz,
1 H, H-1).
13C NMR (CDCl3): d = 36.4 (C-4), 44.8 (C-5), 61.1 (C-3a), 120.5
(C-9), 127.1 (C-8), 127.8 (C-5a), 128.4 (C-2), 128.4 (2C, C-2¢),
128.8 (2C, C-2¢), 128.8 (2C, C-3¢), 129.2 (C-6), 130.7 (C-7), 134.4
(C-9a), 143.3 (C-1¢), 146.4 (C-3), 168.5 (C-1).
Anal. Calcd for C21H21NO3: C, 75.20; H, 6.31; N, 4.18. Found: C,
75.15; H, 6.33; N, 4.15.
exo-1,3a,4,5-Tetrahydro-7-methoxy-4-methyl-5-(4-meth-
oxy)phenylpyrrolo[1,2-a]quinolin-1-one (exo-4i)
Dense oil.
1H NMR (CDCl3): d = 0.78 (d, J = 7.0 Hz, 3 H, CH3), 2.33–2.40 (m,
1 H, H-4), 3.73 (s, 3 H, OCH3), 3.77 (s, 3 H, OCH3), 4.08 (s, 1 H,
H-5), 4.41 (d, J = 1.8 Hz, 1 H, H-3a), 6.26 (dd, J = 6.3, 1.8 Hz, 1 H,
H-2), 6.61 (d, J = 3.0 Hz, 1 H, H-6), 6.82 (d, J = 9.0 Hz, 2 H, H-2¢),
6.88–6.92 (m, 4 H), 8.51 (d, J = 9.0 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 13.4 (CH3), 37.8 (C-5), 50.3 (C-4), 55.2
(OCH3), 55.3 (OCH3), 59.5 (C-3a), 113.8 (C-8), 113.5 (2C, C-2¢),
115.8 (C-6), 119.9 (C-9), 126.3 (C-2), 129.4 (2C, C-2¢), 129.6 (C-
5a), 130.1 (C-9a), 137.5 (C-1¢), 145.7 (C-3), 155.8 (C-7), 158.3 (C-
4¢), 169.2 (C-1).
MS (EI): m/z (%) = 297 (26) [M + 2]+, 295 (8) [M+], 275 (2), 268
(9), 266 (30), 218 (14), 192 (23), 190 (62), 88 (33), 86 (100).
Anal. Calcd for C18H14ClNO: C, 73.10; H, 4.77; N, 4.74. Found: C,
73.07; H, 4.82; N, 4.72.
exo-1,3a,4,5-Tetrahydro-7-chloro-5-phenylpyrrolo[1,2-a]quin-
olin-1-one (exo-4k)
Colorless needles; mp 154–155 °C.
MS (EI): m/z (%) = 335 (216) [M+], 320 (2), 306 (3), 292 (2), 226
(24), 212 (100).
1H NMR (CDCl3): d = 1.88 (dt, J = 12.8, 5.6 Hz, 1 H, H-4ax), 2.34
(d, J = 12.8 Hz, 1 H, H-4eq), 4.28 (d, J = 12.6 Hz, 1 H, H-3a), 4.46
(d, J = 4.8 Hz, 1 H, H-5), 6.279 (dd, J = 5.8, 1.6 Hz, 1 H, H-3),
7.03–7.09 (m, 4 H), 7.25–7.42 (m, 4 H), 8.52 (d, J = 9.0 Hz, 1 H, H-
9).
Anal. Calcd for C21H21NO3: C, 75.20; H, 6.31; N, 4.18. Found: C,
75.16; H, 6.37; N, 4.12.
endo-5a,5b,8,12b-Tetrahydro-11-methoxyindeno[2,3-c]pyrro-
lo[1,2-a]quinolin-8-one (endo-4j)
Colorless needles; mp 173–174 °C
13C NMR (CDCl3): d = 34.8 (C-4), 42.6 (C-5), 56.2 (C-3a), 120.5
(C-9), 126.8 (C-8), 127.6 (C-2), 127.9 (C-5a), 128.3 (C-4¢), 128.5
(4C, C-2¢, C-3¢), 129.1 (C-7), 129.9 (C-6), 135.1 (C-9a), 144.6 (C-
1¢), 147.2 (C-3), 169.0 (C-1).
MS (EI): m/z (%) = 297 (2) [M + 2]+, 295 (6) [M+], 275 (1), 266 (2),
218 (4), 216 (2), 209 (6), 207 (16), 86 (66), 84 (100).
1H NMR (CDCl3): d = 2.52–2.55 (m, 2 H), 3.30 (dq, J = 8.1, 3.6,
1.8 Hz, 1 H, H-4), 3.75 (s, 3 H, OCH3), 4.44 (d, J = 7.8 Hz, 1 H, H-
3a), 4.69 (s, 1 H, H-5), 6.31 (dd, J = 6.0, 1.8 Hz, 1 H, H-3), 6.74 (d,
J = 8.7 Hz, 1 H, H-8), 7.02 (s, 1 H, H-6), 7.07–7.20 (m, 4 H), 7.53
(d, J = 6.6 Hz, 1 H), 8.12 (d, J = 8.7 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 30.6 (CH2), 41.7 (C-5), 45.9 (C-4), 55.3
(OCH3), 61.5 (C-3a), 120.0 (C-8), 114.2 (C-8), 120.8 (C-9), 124.5
(CH), 124.8 (CH), 126.7 (C-2), 127.4 (CH), 128.4 (C-5a), 129.3
(CH), 129.4 (C-9a), 141.5 (C), 145.1 (C), 145.2 (C-3), 155.9 (C-7),
168.5 (C-1).
Anal. Calcd for C18H14ClNO: C, 73.10; H, 4.77; N, 4.74. Found: C,
73.05; H, 4.81; N, 4.65.
endo-1,3a,4,5-Tetrahydro-7-chloro-4-methyl-5-(4-methoxyphe-
nyl)pyrrolo[1,2-a]quinolin-1-one (endo-4l)
Colorless needles; mp 176–177 °C.
1H NMR (CDCl3): d = 1.04 (d, J = 6.4 Hz, 3 H, CH3), 1.64–1.82 (m,
1 H, H-4), 3.58 (d, J = 11.0 Hz, 1 H, H-5), 3.82 (s, 3 H, OCH3), 4.09
(d, J = 11.0 Hz, 1 H, H-3a), 6.36 (dd, J = 6.2, 1.8 Hz, 1 H, H-2),
6.70 (d, J = 2.0 Hz, 1 H, H-6), 6.88 (d, J = 8.6 Hz, 2 H, H-2¢), 7.01
(d, J = 8.6 Hz, 2 H, H-3¢), 7.19 (dd, J = 8.8, 2.0 Hz, 1 H, H-8), 7.32
(dd, J = 6.2, 2.0 Hz, 1 H, H-3), 8.36 (d, J = 8.8 Hz, 1 H, H-9).
MS (EI): m/z (%) = 303 (22) [M+], 288 (4), 274 (6), 263 (5), 248 (4),
205 (28), 149 (18), 134 (17), 84 (100).
Anal. Calcd for C20H17NO2: C, 79.19; H, 5.65; N, 4.62. Found: C,
79.18; H, 5.70; N, 4.58.
exo-5a,5b,8,12b-Tetrahydro-11-methoxyindeno[2,3-c]pyrro-
lo[1,2-a]quinolin-8-one (exo-4j)
Colorless needles; mp 160–161 °C.
13C NMR (CDCl3): d = 15.8 (CH3), 40.2 (C-5), 51.8 (C-4), 55.1
(OCH3), 66.4 (C-3a), 114.1 (2C), 120.2 (C-9), 127.0 (C-2, C-3¢),
128.4 (C-7), 128.9 (C-8), 129.1 (C-5a), 129.6 (C-6), 130.2 (2C, C-
2¢), 134.1 (C-9a), 135.6 (C-1¢), 145.6 (C-3), 158.6 (C-4¢), 168.3 (C-
1).
MS (EI): m/z (%) = 341 (84) [M + 2]+, 339 (24) [M+], 326 (1), 324
(6), 310 (2), 296 (2), 267 (9), 218 (12), 216 (20), 206 (8), 204 (21),
135 (87), 43 (100).
1H NMR (CDCl3): d = 2.43–2.55 (m, 1 H, H-4), 2.97 (d, J = 16.2
Hz, 1 H, CHH), 3.33 (dd, J = 16.2, 6.2 Hz, 1 H, CHH), 3.78 (d,
J = 11.8 Hz, 1 H, C-5), 3.88 (s, 3 H, OCH3), 4.46 (d, J = 6.0 Hz,
1 H, H-3a), 6.31 (d, J = 5.8 Hz, 1 H, H-2), 6.90 (dd, J = 2.8, 9.0 Hz,
1 H, H-8), 7.07 (d, J = 2.8 Hz, 1 H, H-6), 7.18–7.31 (m, 5 H, ArH,
H-3), 8.29 (d, J = 9.0 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 34.4 (CH2), 42.5 (C-5), 47.3 (C-4), 55.5
(OCH3), 60.5 (C-3a), 112.4 (C-8), 115.5 (C-6), 120.7 (C-9), 124.2
(CH), 125.4 (CH), 126.9 (C-2), 127.2 (C-5a), 127.8 (CH), 128.6 (C-
9a), 129.2 (CH), 140.0 (C), 143.1 (C), 145.6 (C-3), 155.5 (C-7),
168.2 (C-1).
Anal. Calcd for C20H18ClNO2: C, 70.69; H, 5.34; N, 4.12. Found: C,
70.66; H, 5.38; N, 4.07.
exo-1,3a,4,5-Tetrahydro-7-chloro-4-methyl-5-(4-methoxyphe-
nyl)pyrrolo[1,2-a]quinolin-1-one (exo-4l)
Colorless needles; mp 127–128 °C.
MS (EI): m/z (%) = 303 (21) [M+], 288 (3), 274 (4), 260 (3), 248 (3),
212 (27), 115 (9), 86 (68), 84 (100).
1H NMR (CDCl3): d = 0.75 (d, J = 7.4 Hz, 3 H, CH3), 2.39 (q,
J = 6.0 Hz, 1 H, H-4), 3.76 (s, 3 H, OCH3), 4.07 (s, 1 H, H-5), 4.42
(s, 1 H, H-3a), 6.26 (dd, J = 6.0, 1.8 Hz, 1 H, H-2), 6.80–6.98 (m,
5 H), 7.08 (d, J = 2.0 Hz, 1 H, H-6), 7.9 (dd, J = 6.0, 2.0 Hz, 1 H, H-
3), 8.57 (d, J = 9.0 Hz, 1 H, H-9).
Anal. Calcd for C20H17NO2: C, 79.19; H, 5.65; N, 4.62. Found: C,
79.15; H, 5.58; N, 4.55.
Synthesis 2006, No. 12, 2053–2063 © Thieme Stuttgart · New York

2060
W. Zhang et al.
PAPER
exo-5a,5b,6,7,8,12b-Hexahydroindeno[2,3-c]pyrrolo[1,2-
a]quinolin-8-one (exo-5b)
Colorless needles; mp 138–139 °C.
1H NMR (CDCl3): d = 1.84–2.09 (m, 1 H), 2.24–2.35 (m, 1 H),
2.57–2.70 (m, 2 H), 2.89–2.94 (m, 2 H), 3.14–3.22 (m, 1 H, H-4),
4.31 (dt, J = 7.5, 3.0 Hz, 1 H, H-3a), 4.48 (d, J = 8.1 Hz, 1 H, H-5),
7.06 (t, J = 7.8 Hz, 1 H, H-7), 7.12–7.23 (m, 5 H), 7.49 (d, J = 7.8
Hz, 1 H, CH), 7.56 (d, J = 7.5 Hz, 1 H, CH), 8.46 (d, J = 8.1 Hz,
1 H, H-9).
13C NMR (CDCl3): d = 21.4 (C-3), 30.6 (CH2), 31.8 (C-2), 44.9 (C-
5), 46.3 (C-4), 57.6 (C-3a), 119.8 (C-9), 124.4 (C-7), 124.9 (CH),
125.0 (CH), 126.7 (CH), 126.7 (CH), 127.3 (C-8), 128.3 (C-5a),
128.9 (C-6), 135.7 (C-9a), 141.6 (C), 145.5 (C), 173.7 (C-1).
13C NMR (CDCl3): d = 13.2 (CH3), 37.2 (C-5), 49.8 (C-4), 55.1
(OCH3), 59.2 (C-3a), 113.8 (2C), 119.8 (C-9), 126.7 (C-2, C-2¢),
127.5 (C-8), 128.8 (C-7), 129.0 (C-6), 129.4 (2C, C-3¢), 130.8 (C-
5a), 134.1(C-1¢), 136.7 (C-9a), 146.4 (C-3), 158.3 (C-4¢), 169.6 (C-
1).
MS (EI): m/z (%) = 341 (4) [M + 2]+, 339 (9) [M+], 324 (1), 319 (2),
233 (8), 231 (24), 218 (24), 216 (69), 209 (31), 207 (100), 86 (61),
84 (94).
Anal. Calcd for C20H18ClNO2: C, 70.69; H, 5.34; N, 4.12. Found: C,
70.64; H, 5.36; N, 4.06.
endo-1,2,3,3a,4,5-Hexahydro-5-methyl-5-phenylpyrrolo[1,2-
a]quinolin-1-one (endo-5a)
Colorless needles; mp 157–158 °C.
MS (EI): m/z (%) = 275 (15) [M+], 258 (4), 246 (1), 230 (1), 220 (7),
218 (8), 184 (7), 176 (10), 129 (9), 93 (100).
1H NMR (CDCl3): d = 1.62–1.74 (m, 1 H), 1.77 (s, 3 H, CH3), 2.07–
2.10 (m, 2 H), 2.25–2.32 (m, 1 H, H-4), 2.51–2.72 (m, 2 H, H-2),
4.12–4.22 (m, 1 H, H-3a), 6.78 (d, J = 7.8 Hz, 1 H, H-8), 6.96 (t,
J = 7.5 Hz, 1 H, H-7), 7.17–7.32 (m, 6 H), 8.68 (d, J = 8.1 Hz, 1 H,
H-9).
13C NMR (CDCl3): d = 25.1 (C-3), 29.6 (CH3), 32.4 (C-2), 42.7 (C-
5), 48.3 (C-4), 54.3 (C-3a), 119.2 (C-9), 123.9 (C-7), 125.6 (C-5a),
126.8 (C-4¢), 127.2 (2C, C-3¢), 128.2 (2C, C-2¢), 128.8 (C-8), 130.0
(C-6), 136.0 (C-9a), 149.9 (C-1¢), 173.4 (C-1).
Anal. Calcd for C19H17NO: C, 82.88; H, 6.22; N, 5.09. Found: C,
82.81; H, 6.24; N, 5.05.
endo-1,2,3,3a,4,5-Hexahydro-7-methyl-5-phenylpyrrolo[1,2-
a]quinolin-1-one (endo-5c)
Colorless needles; mp 150–151 °C.
1H NMR (CDCl3): d = 1.61–1.72 (m, 1 H, H-3), 2.02–2.18 (m, 3 H),
2.24 (s, 3 H, CH3), 2.43–2.64 (m, 2 H, H-2), 3.81 (dq, J = 10.2, 3.0
Hz, 1 H, H-3a), 4.30 (d, J = 4.8 Hz, 1 H, H-5), 6.88 (d, J = 1.8 Hz,
1 H, H-6), 6.99 (d, J = 7.8 Hz, 2 H, H-2¢), 7.09 (dd, J = 8.4, 1.8 Hz,
1 H, H-8), 7.20 (t, J = 7.5 Hz, 1 H, H-4¢), 7.28 (t, J = 7.8 Hz, 2 H,
H-3¢), 8.76 (d, J = 8.1 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 20.7 (CH3), 25.4 (C-3), 32.3 (C-2), 37.3 (C-
4), 42.7 (C-5), 52.6 (C-3a), 118.6 (C-8), 126.3 (C-8), 126.4 (C-4¢),
128.3 (C-6), 128.3 (2C, C-3¢), 128.6 (2C, C-2¢), 130.9 (C-7), 133.1
(C-5a), 134.9 (C-9a), 140.4 (C-1¢), 173.5 (C-1).
MS (EI): m/z (%) = 277 (60) [M+], 262 (100), 244 (1), 222 (9), 206
(15), 200 (18), 184 (22).
Anal. Calcd for C19H19NO: C, 82.28; H, 6.90; N, 5.05. Found: C,
82.25; H, 6.95; N, 4.98.
exo-1,2,3,3a,4,5-Hexahydro-5-methyl-5-phenylpyrrolo[1,2-
a]quinolin-1-one (exo-5a)
Colorless needles; mp 105–106 °C.
1H NMR (CDCl3): d = 1.60–1.66 (m, 1 H, H-3), 1.81 (s, 3 H, CH3),
1.95 (t, J = 12.6 Hz, 1 H, H-4ax), 2.03–2.14 (m, 1 H, H-2), 2.28 (dd,
J = 13.5, 1.8 Hz, 1 H, H-4eq), 2.46–2.52 (m, 2 H, H-2), 3.58–3.65
(m, 1 H, H-3a), 7.02 (d, J = 7.5 Hz, 2 H, H-2¢), 7.12 (t, J = 7.8 Hz,
1 H, H-8), 7.19 (d, J = 7.2 Hz, 1 H, H-6), 7.24–7.29 (m, 3 H), 7.32
(t, J = 7.5 Hz, 1 H, H-7), 8.88 (d, J = 8.1 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 25.2 (C-3), 30.2 (CH3), 32.2 (C-2), 42.1 (C-
5), 46.3 (C-4), 53.5 (C-3a), 118.9 (C-9), 123.8 (C-7), 126.1 (C-5a),
127.2 (2C, C-3¢), 127.4 (C-4¢), 128.1 (2C, C-2¢), 128.6 (C-8), 129.4
(C-6), 137.3 (C-9a), 149.9 (C-1¢), 173.5 (C-1).
MS (EI): m/z (%) = 277 (100) [M+], 262 (16), 222 (55), 206 (12),
198 (21), 178 (16), 144 (37).
Anal. Calcd for C19H19NO: C, 82.28; H, 6.90; N, 5.05. Found: C,
82.31; H, 6.92; N, 4.95.
exo-1,2,3,3a,4,5-Hexahydro-7-methyl-5-phenylpyrrolo[1,2-
a]quinolin-1-one (exo-5c)
Colorless needles; mp: 122–123 °C.
1H NMR (CDCl3): d = 1.66–1.80 (m, 1 H, H-3), 1.89 (q, J = 12.3
Hz, 1 H), 2.14 (s, 3 H, CH3), 2.24–2.39 (m, 2 H), 2.48–2.71 (m,
2 H), 4.03–4.10 (m, 1 H, H-3a), 4.16 (dd, J = 12.6, 5.7 Hz, 1 H, H-
5), 6.57 (s, 1 H, H-6), 7.02 (d, J = 8.1 Hz, 1 H, H-8), 7.17 (d, J = 7.8
Hz, 2 H, H-2¢), 7.24–7.38 (m, 3 H, H-8, H-3¢), 8.58 (d, 1 H, J = 8.7
Hz, H-9).
13C NMR (CDCl3): d = 20.8 (CH3), 25.0 (C-3), 32.0 (C-2), 40.5 (C-
5), 44.9 (C-4), 57.6 (C-3a), 118.9 (C-9), 126.7 (C-8), 127.8 (C-4¢),
128.5 (2C, C-3¢), 128.9 (2C, C-2¢), 129.2 (C-6), 130.1 (C-7), 133.1
(C-5a), 134.4 (C-9a), 145.1 (C-1¢), 173.1 (C-1).
MS (EI): m/z (%) = 277 (44) [M+], 262 (20), 248 (25), 220 (14), 206
(8), 198 (35), 184 (100).
Anal. Calcd for C19H19NO: C, 82.28; H, 6.90; N, 5.05. Found: C,
82.22; H, 6.97; N, 4.95.
endo-5a,5b,6,7,8,12b-Hexahydroindeno[2,3-c]pyrrolo[1,2-
a]quinolin-8-one (endo-5b)
Colorless needles; mp 167–168 °C.
1H NMR (CDCl3): d = 1.73–1.86 (m, 1 H, H-3), 2.30–2.41 (m, 1 H,
H-3), 2.47–2.60 (m, 2 H), 2.82 (d, J = 15.9 Hz, 1 H, H-2), 3.28 (dd,
J = 15.9, 6.6 Hz, 1 H, H-2), 3.37–3.46 (m, 1 H, H-3a), 4.39 (d,
J = 5.7 Hz, 1 H, H-5), 7.12–7.33 (m, 6 H), 7.22 (d, J = 7.5 Hz, 1 H),
8.64 (d, J = 8.4 Hz, 1 H, H-9).
MS (EI): m/z (%) = 277 (19) [M+], 262 (4), 222 (7), 198 (30), 144
(9), 84 (100).
Anal. Calcd for C19H19NO: C, 82.28; H, 6.90; N, 5.05. Found: C,
82.24; H, 6.83; N, 5.96.
13C NMR (CDCl3): d = 23.6 (C-3), 31.8 (CH2), 34.0 (C-2), 44.1 (C-
5), 46.7 (C-4), 56.3 (C-3a), 119.6 (C-9), 123.6 (C-7), 124.0 (CH),
125.3 (CH), 126.1 (C-5a), 126.6 (CH), 126.9 (CH), 127.2 (C-8),
130.2 (C-6), 135.9 (C-9a), 140.1 (C), 144.7 (C), 173.7 (C-1).
MS (EI): m/z (%) = 275 (42) [M+], 258 (9), 246 (2), 230 (3), 220
(13), 218 (24), 204 (9), 184 (100).
endo-1,2,3,3a,4,5-Hexahydro-5,7-dimethyl-5-phenylpyrro-
lo[1,2-a]quinolin-1-one (endo-5d)
Colorless needles; mp 170–171 °C.
1H NMR (CDCl3): d = 1.61–1.71 (m, 1 H, H-3), 1.75 (s, 3 H, CH3),
1.99–2.05 (m, 2 H, H-4), 2.15 (s, 3 H, CH3), 2.22–2.26 (m, 1 H, H-
3), 2.37 (dd, J = 13.2, 2.0 Hz, 1 H, H-2), 2.49–2.66 (m, 1 H, H-2),
4.09–4.17 (m, 1 H, H-3a), 6.57 (d, J = 1.6 Hz, 1 H, H-6), 7.00 (dd,
Anal. Calcd for C19H17NO: C, 82.88; H, 6.22; N, 5.09. Found: C,
82.85; H, 6.26; N, 5.02.
Synthesis 2006, No. 12, 2053–2063 © Thieme Stuttgart · New York

PAPER
Diels–Alder Reactions of N-Acyliminium Cations with Olefins
2061
J = 8.4, 1.6 Hz, 1 H, H-8), 7.17–7.29 (m, 5 H, ArH), 8.56 (d, J = 8.0
Anal. Calcd for C21H23NO: C, 78.47; H, 7.21; N, 4.36. Found: C,
Hz, 1 H, H-9).
78.42; H, 7.22; N, 4.27.
13C NMR (CDCl3): d = 20.7 (CH3), 24.9 (C-3), 29.4 (CH3), 31.8 (C-
2), 42.5 (C-5), 48.4 (C-4), 54.1(C-3a), 119.0 (C-9), 125.9 (C-4¢),
127.0 (2C, C-3¢), 127.4 (C-8), 128.0 (2C, C-2¢), 128.2 (C-6), 133.0
(C-7), 133.6 (C-5a), 134.9 (C-9a), 149.9 (C-1¢), 172.9 (C-1).
MS (EI): m/z (%) = 291 (63) [M+], 276 (100), 248 (4), 236 (8), 220
(21), 214 (150), 198 (22).
endo-5a,5b,6,7,8,12b-Hexahydro-11-methylindeno[2,3-c]pyrro-
lo[1,2-a]quinolin-8-one (endo-5f)
Colorless needles; mp 156–157 °C.
1H NMR (CDCl3): d = 1.92–2.02 (m, 1 H), 2.26 (s, 3 H, CH3), 2.20–
2.32 (m, 1 H), 2.55–2.69 (m, 2 H), 2.86–2.90 (m, 2 H), 3.10–4.15
(m, 1 H, H-4), 4.25 (dt, J = 7.8, 2.7 Hz, 1 H, H-3a), 4.41 (d, J = 7.8
Hz, 1 H, H-5), 6.97 (d, J = 8.7 Hz, 1 H, H-8), 7.15–7.21 (m, 3 H),
7.26 (s, 1 H, H-6), 7.55 (d, J = 7.8 Hz, 1 H, CH), 8.34 (d, J = 8.7 Hz,
1 H, H-9).
13C NMR (CDCl3): d = 21.0 (CH3), 21.3 (C-3), 30.5 (CH2), 31.7 (C-
2), 44.9 (C-5), 46.2 (C-4), 57.2 (C-3a), 119.6 (C-9), 124.8 (C-8),
125.0 (CH), 126.6 (CH), 127.2 (CH), 127.4 (CH), 128.0 (C-6),
129.2 (C-7), 133.2 (C-5a), 133.8 (C-9a), 141.7 (C), 145.6 (C), 173.3
(C-1).
Anal. Calcd for C20H21NO: C, 82.44; H, 7.26; N, 4.81. Found: C,
82.41; H, 7.35; N, 4.74.
exo-1,2,3,3a,4,5-Hexahydro-5,7-dimethyl-5-phenylpyrrolo[1,2-
a]quinolin-1-one (exo-5d)
Colorless needles; mp 137–138 °C.
1H NMR (CDCl3): d = 1.58–1.69 (m, 1 H, H-3), 1.79 (s, 3 H, CH3),
1.92 (t, J = 12.8 Hz, 1 H, H-4ax), 2.01–2.09 (m, 1 H, H-2), 2.24 (dd,
J = 12.8, 2.8 Hz, 1 H, H-4eq), 2.29 (s, 3 H, CH3), 2.39–2.59 (m, 2 H,
H-2), 3.56–3.59 (m, 1 H, H-3a), 7.05 (d, J = 7.6 Hz, 2 H, H-2¢), 7.05
(s, 1 H, H-6), 7.11 (dd, J = 8.0, 1.6 Hz, 1 H, H-8), 7.17 (t, J = 7.6
Hz, 1 H, H-4¢), 7.25 (t, J = 7.6 Hz, 2 H, H-3¢), 8.75 (d, J = 8.4 Hz,
1 H, H-9).
MS (EI): m/z (%) = 289 (56) [M+], 272 (12), 244 (3), 232 (21), 217
(20), 198 (100), 144 (15), 115 (34), 91 (54).
Anal. Calcd for C20H19NO: C, 83.01; H, 6.62; N, 4.84. Found: C,
82.95; H, 6.65; N, 4.77.
13C NMR (CDCl3): d = 21.0 (CH3), 25.1 (C-3), 30.1 (CH3), 32.1 (C-
2), 42.0 (C-5), 46.5 (C-4), 53.6 (C-3a), 118.7 (C-9), 126.0 (C-4¢),
127.2 (2C, C-3¢), 128.1 (2C, C-2¢), 128.1 (C-8), 128.9 (C-6), 131.5
(C-7), 133.1 (C-5a), 134.3 (C-9a), 150.0 (C-1¢), 173.3 (C-1).
MS (EI): m/z (%) = 291 (70) [M+], 276 (35), 248 (5), 234 (12), 220
(21), 212 (100), 198 (74).
exo-5a,5b,6,7,8,12b-Hexahydro-11-methylindeno[2,3-c]pyrro-
lo[1,2-a]quinolin-8-one (exo-5f)
Dense oil.
1H NMR (CDCl3): d = 1.74–1.84 (m, 1 H), 2.17 (s, 3 H, CH3), 2.30–
2.39 (m, 1 H), 2.49–2.58 (m, 3 H), 2.82 (d, J = 16.5 Hz, 1 H, H-
2equ), 3.27 (d, J = 16.5, 6.3 Hz, 1 H, H-2ax), 3.36–4.42 (m, 1 H, H-
3a), 4.33 (d, J = 6.0 Hz, 1 H, H-5), 7.11 (d, J = 8.7 Hz, 1 H, H-8),
7.15–7.31 (m, 5 H), 8.53 (d, J = 8.7 Hz, 1 H, H-9).
Anal. Calcd for C20H21NO: C, 82.44; H, 7.26; N, 4.81. Found: C,
82.37; H, 7.31; N, 4.72.
13C NMR (CDCl3): d = 21.0 (C-3), 31.7 (CH2), 33.9 (C-2), 44.2 (C-
5), 46.6 (C-4), 56.3 (C-3a), 119.4 (C-9), 124.0 (C-8), 125.3 (CH),
126.0 (CH), 126.6 (CH), 126.9 (CH), 127.9 (C-6), 130.5 (C-7),
133.0 (C-5a), 133.4 (C-9a), 139.9 (C), 144.7 (C), 173.3 (C-1).
MS (EI): m/z (%) = 289 (34) [M+], 272 (8), 244 (1), 232 (32), 217
(12), 198 (67), 144 (15), 115 (100).
endo-1,2,3,3a,4,5-Hexahydro-4,7-dimethyl-5-(4-methoxy)phe-
nylpyrrolo[1,2-a]quinolin-1-one (endo-5e)
Colorless needles; mp 195–197 °C.
1H NMR (CDCl3): d = 0.86 (d, J = 6.0 Hz, 3 H, CH3), 1.69–1.88 (m,
2 H, H-3), 2.12 (s, 3 H, CH3), 2.27–2.33 (m, 1 H, H-4), 2.47–2.69
(m, 2 H, H-4, H-2), 3.56 (d, J = 11.4 Hz, 1 H, H-5), 3.61 (dd,
J = 10.5, 3.9 Hz, 1 H, H-3a), 3.82 (s, 3 H, OCH3), 6.50 (s, 1 H, H-
6), 6.87 (d, J = 8.7 Hz, 2 H, H-2¢), 6.97–7.03 (m, 3 H, H-8, H-3¢),
8.63 (d, J = 9.0 Hz, 1 H, H-9).
Anal. Calcd for C20H19NO: C, 83.01; H, 6.62; N, 4.84. Found: C,
82.98; H, 6.68; N, 4.80%.
endo-1,2,3,3a,4,5-Hexahydro-7-methoxy-5-methyl-5-phe-
nylpyrrolo[1,2-a]quinolin-1-one (endo-5g)
Colorless needles; mp 158–159 °C.
1H NMR (CDCl3): d = 1.62–1.72 (m, 1 H), 1.76 (s, 3 H, CH3), 2.05–
2.11 (m, 2 H), 2.24–2.33 (m, 1 H), 2.50–2.73 (m, 2 H, H-2), 3.63 (s,
3 H, OCH3), 4.12–4.17 (m, 1 H, H-3a), 6.30 (d, J = 2.7 Hz, 1 H, H-
6), 6.77 (dd, J = 9.0, 2.7 Hz, 1 H, H-8), 7.18–7.31 (m, 5 H, ArH),
8.61 (d, J = 9.0 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 24.8 (C-3), 29.4 (CH3), 31.8 (C-2), 42.8 (C-
5), 48.2 (C-4), 54.1 (C-3a), 55.1 (OCH3), 111.8 (C-8), 115.1 (C-6),
120.3 (C-9), 126.0 (C-4¢), 127.0 (2C, C-3¢), 128.0 (2C, C-2¢), 129.6
(C-5a), 136.8 (C-9a), 149.5 (C-1¢), 155.3 (C-7), 172.6 (C-1).
13C NMR (CDCl3): d = 14.9 (CH3), 20.8 (CH3), 24.3 (C-3), 32.2 (C-
2), 42.1 (C-5), 51.4 (C-4), 55. 1 (OCH3), 62.5 (C-3a), 113.8 (2C, C-
2¢), 118.2 (C-9), 127.5 (C-8), 129.9 (C-6), 130.2 (2C, C-3¢), 130.4
(2C), 130.4 (C-7), 132.8 (C-5a), 134.0 (C-9a), 135.8 (C-1¢), 158.2
(C-4¢), 173.3 (C-1).
MS (EI): m/z(%) = 321 (12) [M+], 306 (1), 292 (1), 264 (1), 250 (2),
237 (3), 224 (3), 198 (100).
Anal. Calcd for C21H23NO: C, 78.47; H, 7.21; N, 4.36. Found: C,
78.45; H, 7.15; N, 4.31.
exo-1,2,3,3a,4,5-Hexahydro-4,7-dimethyl-5-(4-methoxy)phe-
nylpyrrolo[1,2-a]quinolin-1-one (exo-5e)
Colorless needles; mp 148–149 °C.
MS (EI): m/z (%) = 307 (100) [M+], 292 (70), 277 (2), 264 (4), 252
(15), 236 (13).
1H NMR (CDCl3): d = 0.99 (d, J = 6.9 Hz, 3 H, CH3), 1.81–1.90 (m,
2 H), 2.01–2.09 (m, 1 H), 2.23 (s, 3 H, CH3), 2.48–2.61 (m, 2 H),
3.75 (s, 3 H, OCH3), 3.93–3.40 (m, 2 H, H-3a, H-5), 6.78–6.89 (m,
5 H), 7.08 (d, J = 8.4 Hz, 1 H, H-8), 8.69 (d, J = 8.4 Hz, 1 H, H-9).
Anal. Calcd for C20H21NO2: C, 78.15; H, 6.89; N, 4.56. Found: C,
78.12; H, 6.96; N, 4.52%.
exo-1,2,3,3a,4,5-Hexahydro-7-methoxy-5-methyl-5-phenylpyr-
rolo[1,2-a]quinolin-1-one (exo-5g)
Colorless needles; mp 137–138 °C.
1H NMR (CDCl3): d = 1.55–1.71 (m, 1 H, H-3), 1.78 (s, 3 H, CH3),
1.92 (t, J = 12.3 Hz, 1 H, H-4ax), 1.99–2.08 (m, 1 H, H-2), 2.24 (dd,
J = 12.3, 1.8 Hz, 1 H, H-4equal), 2.39–2.58 (m, 2 H, H-2), 3.56–3.62
13C NMR (CDCl3): d = 13.1 (CH3), 20.5 (C-3), 32.0 (C-2), 37.3 (C-
5), 50.1 (C-4), 54.7 (OCH3), 55.0 (C-3a), 113.4 (C-3¢), 118.3 (C-9),
125.0 (C-8), 128.0 (C-6), 129.5(C-2¢), 131.6 (C-7), 133.5 (C-5a),
134.3 (C-9a), 138.4 (C-1¢), 157.8 (C-4¢), 173.8 (C-1).
MS (EI): m/z (%) = 321 (64) [M+], 306 (8), 292 (12), 266 (6), 250
(6), 237 (9), 224 (16), 198 (100).
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W. Zhang et al.
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(m, 1 H, H-3a), 3.75 (s, 3 H, OCH3), 6.76 (d, J = 2.7 Hz, 1 H, H-6),
6.87 (dd, J = 8.7, 2.7 Hz, 1 H, H-8), 7.01 (d, J = 7.8 Hz, 2 H, H-2¢),
7.16 (t, J = 7.8 Hz, 1 H, H-3¢), 7.25 (t, J = 7.8 Hz, 2 H, H-3¢), 8.81
(d, J = 9.3 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 25.0 (C-3), 30.1 (CH3), 32.1 (C-2), 42.3 (C-
5), 46.5 (C-4), 53.5 (C-3a), 55.3 (OCH3), 112.5 (C-8), 113.8 (C-6),
120.0 (C-9), 126.1 (C-4¢), 127.1 (2C, C-3¢), 128.1 (2C, C-2¢), 130.4
(C-5a), 133.3 (C-9a), 149.6 (C-1¢), 155.5 (C-7), 173.0 (C-1).
MS (EI): m/z (%) = 299 (28) [M + 2]+, 297 (100) [M+], 244 (22),
242 (87), 220 (8), 218 (20), 164 (11), 166 (54), 86 (8), 88 (27).
Anal. Calcd for C18H16ClNO: C, 72.60; H, 5.42; N, 4.70. Found: C,
72.62; H, 5.46; N, 4.62.
exo-1,2,3,3a,4,5-Hexahydro-7-chloro-5-phenylpyrrolo[1,2-
a]quinolin-1-one (exo-5i)
Colorless needles; mp 131–132 °C.
MS (EI): m/z (%) = 307 (100) [M+], 292 (27), 264 (5), 252 (11), 236
(14), 228 (61).
1H NMR (CDCl3): d = 1.61–1.76 (m, 1 H, H-3), 1.99–2.20 (m, 3 H),
2.42–2.64 (m, 2 H), 3.76–3.83 (m, 1 H, H-3a), 4.29 (d, J = 5.1 Hz,
1 H, H-5), 6.97 (d, J = 7.8 Hz, 2 H, H-2¢), 7.05 (d, J = 1.8 Hz, 1 H,
H-6), 7.23–7.31 (m, 4 H), 8.85 (d, J = 9.0 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 25.3 (C-3), 32.2 (C-2), 37.0 (C-5), 42.6 (C-
4), 52.5 (C-3a), 120.1 (C-9), 126.6 (C-4¢), 127.3 (C-8), 127.7 (C-6),
128.3 (C-7), 128.5 (4C, C-2¢, C-3¢), 130.2 (C-5a), 135.9 (C-9a),
145.5 (C-1¢), 173.6 (C-1).
Anal. Calcd for C20H21NO2: C, 78.15; H, 6.89; N, 4.56. Found: C,
78.08; H, 6.92; N, 4.49.
endo-1,2,3,3a,4,5-Hexahydro-7-methoxy-4-methyl-5-(4-meth-
oxy)phenylpyrrolo[1,2-a]quinolin-1-one (endo-5h)
Colorless needles; mp 160–161 °C.
1H NMR (CDCl3): d = 0.99 (d, J = 6.9 Hz, 3 H, CH3), 1.76–1.92 (m,
2 H), 2.02–2.09 (m, 1 H), 2.49–2.62 (m, 2 H, H-2), 3.71 (s, 3 H,
OCH3), 3.76 (s, 3 H, OCH3), 3.94–3.99 (m, 2 H, H-3a, H-5), 6.58
(d, J = 1.5 Hz, 1 H, H-6), 6.80 (d, J = 8.1 Hz, 2 H, H-2¢), 6.85 (dd,
J = 7.8, 1.5 Hz, 1 H, H-8), 6.88 (d, J = 8.7 Hz, 2 H, H-3¢), 8.73 (d,
J = 8.7 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 13.1 (CH3), 20.5 (C-3), 32.0 (C-2), 37.5 (C-
5), 50.4 (C-4), 54.8 (OCH3), 55.1 (OCH3), 113.1 (C-8), 113.5 (2C,
C-3¢), 115.7 (C-6), 119.9 (C-9), 126.8 (C-5a), 129.6 (2C, C-2¢),
130.5 (C-9a), 138.2 (C-1¢), 155.6 (C-7), 157.9 (C-4¢), 173.5 (C-1).
MS (EI): m/z (%) = 299 (14) [M + 2]+, 297 (58) [M+], 284 (3), 282
(7), 244 (8), 242 (28), 220 (29), 218 (100), 84 (18), 86 (57).
Anal. Calcd for C18H16ClNO: C, 72.60; H, 5.42; N, 4.70. Found: C,
72.56; H, 5.43; N, 4.67.
endo-1,2,3,3a,4,5-Hexahydro-7-chloro-4-methyl-5-(4-methoxy-
phenyl)pyrrolo[1,2-a]quinolin-1-one (endo-5j)
Colorless needles; mp 174–175 °C.
1H NMR (CDCl3): d = 0.85 (d, J = 6.9 Hz, 3 H, CH3), 1.63–1.91 (m,
2 H, H-3), 2.25–2.37 (m, 1 H, H-4), 2.49–2.73 (m, 2 H, H-4, H-2),
3.56 (d, J = 11.7 Hz, 1 H, H-5), 3.66 (dt, J = 9.9, 6.6 Hz, 1 H, H-3a),
3.82 (s, 3 H, OCH3), 6.66 (d, J = 1.8 Hz, 1 H, H-6), 6.87 (d, J = 8.7
Hz, 2 H, H-2¢), 7.01 (d, J = 8.7 Hz, 2 H, H-3¢), 7.13 (dd, J = 8.7, 1.8
Hz, 1 H, H-8), 8.74 (d, J = 9.0 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 14.8 (CH3), 24.3 (C-3), 32.0 (C-2), 41.6 (C-
5), 51.5 (C-4), 55.2 (OCH3), 62.6 (C-3a), 114.2 (2C), 119.7(C-9),
126.9 (C-8), 128.5 (C-7), 129.8 (C-6), 130.2 (2C), 132.1 (C-5a),
134.7 (C-9a), 135.1 (C-1¢), 158.6 (C-4¢), 173.6 (C-1).
MS (EI): m/z (%) = 337 (100) [M+] , 322 (8), 308 (6), 294 (2), 266
(5), 228 (9), 214 (42), 57 (27).
Anal. Calcd for C21H23NO3: C, 74.75; H, 6.87; N, 4.15. Found: C,
74.72; H, 6.95; N, 4.10%.
exo-1,2,3,3a,4,5-Hexahydro-7-methoxy-4-methyl-5-(4-meth-
oxy)phenylpyrrolo[1,2-a]quinolin-1-one (exo-5h)
Dense oil.
1H NMR (CDCl3): d = 0.87 (d, J = 6.3 Hz, 3 H, CH3), 1.68–1.92 (m,
2 H), 2.26–2.38 (m, 1 H), 2.48–2.72 (m, 2 H, H-2), 3.61 (s, 3 H,
OCH3), 3.66–3.77 (m, 2 H, H-3a, H-5), 3.81 (s, 3 H, OCH3), 6.23
(d, J = 1.5 Hz, 1 H, H-6), 6.75 (dd, J = 8.1, 1.5 Hz, 1 H, H-6), 6.86
(d, J = 8.7 Hz, 2 H, H-2¢), 7.02 (d, J = 8.7 Hz, 2 H, H-3¢), 8.69 (d,
J = 8.7 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 14.9 (CH3), 24.3 (C-3), 32.2 (C-2), 42.1 (C-
5), 51.7 (C-4), 55.2 (2C, 2CH3), 62.6 (C-3a), 111.7 (C-8), 113.9
(2C, C-3¢), 115.6 (C-6), 119.6 (C-9), 130.2 (2C, C-2¢), 130.9 (C-5a),
131.8 (C-9a), 135.5 (C-1¢), 155.3 (C-7), 158.4 (C-4¢), 173.0 (C-1).
MS (EI): m/z (%) = 343 (8) [M + 2]+, 341 (22) [M+], 312 (3), 286
(3), 246 (2), 244 (7), 234 (6), 232 (12), 220 (34), 218 (100).
Anal. Calcd for C20H20ClNO2: C, 70.27; H, 5.90; N, 4.10. Found: C,
70.24; H, 5.96; N, 4.02.
exo-1,2,3,3a,4,5-Hexahydro-7-chloro-4-methyl-5-(4-methoxy-
phenyl)pyrrolo[1,2-a]quinolin-1-one (exo-5j)
Colorless needles; mp 95–97 °C.
1H NMR (CDCl3): d = 0.99 (d, J = 6.9 Hz, 3 H, CH3), 1.79–2.07 (m,
2 H, H-3), 2.08 (q, J = 6.9 Hz, 1 H), 2.47–2.61 (m, 2 H, H-4, H-2),
3.77 (s, 3 H, OCH3), 3.98 (s, 2 H, H-3a, H-5), 6.83 (d, J = 8.7 Hz,
4 H, H-2¢, H-3¢), 7.05 (d, J = 8.4 Hz, 1 H, H-6), 7.24 (dd, J = 8.7,
2.4 Hz, 1 H, H-8), 8.79 (d, J = 9.0 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 13.1 (CH3), 24.7 (C-3), 32.1 (C-2), 37.1 (C-
5), 50.2 (C-4), 54.8 (OCH3), 55.2 (C-3a), 113.7 (C-3¢), 119.9 (C-9),
127.3 (C-8), 127.4 (C-6), 128.7 (C-6), 129.5 (C-2¢), 130.9 (C-5a),
135.5 (C-9a), 137.6 (C-1¢), 158.2 (C-4¢), 174.2 (C-1).
MS (EI): m/z (%) = 337 (58) [M+], 322 (4), 308 (3), 294 (2), 266 (6),
228 (11), 214 (91), 57 (100).
Anal. Calcd for C21H23NO3: C, 74.75; H, 6.87; N, 4.15. Found: C,
74.69; H, 6.88; N, 4.08.
endo-1,2,3,3a,4,5-Hexahydro-7-chloro-5-phenylpyrrolo[1,2-
a]quinolin-1-one (endo-5i)
Colorless needles; mp 152–153 °C.
MS (EI): m/z (%) = 343 (3) [M + 2]+, 341 (8) [M+], 312 (3), 272 (7),
270 (14), 246 (1), 244 (3), 234 (5), 232 (10), 220 (35), 218 (100).
1H NMR (CDCl3): d = 1.65–1.80 (m, 1 H, H-3), 1.89 (q, J = 12.6
Hz, 1 H, H-4), 2.26–2.38 (m, 2 H), 2.46–2.68 (m, 2 H), 4.01–4.10
(m, 1 H, H-3a), 4.13 (dd, J = 12.3, 5.7 Hz, 1 H, H-5), 6.73 (d,
J = 1.8 Hz, 1 H, H-6), 7.12–7.17 (m, 3 H, H-4¢, H-2¢), 7.25–7.39 (m,
3 H, H-6, H-3¢), 8.70 (d, J = 9.0 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 25.0 (C-3), 32.0 (C-2), 39.7 (C-5), 44.9 (C-
4), 57.5 (C-3a), 120.3 (C-9), 127.1 (C-4¢), 127.6 (C-8), 128.6 (2C,
C-3¢), 128.9 (C-7), 129.3 (2C, C-2¢), 129.5 (C-6), 131.3 (C-5a),
135.4 (C-9a), 143.9 (C-1¢), 173.4 (C-1).
Anal. Calcd for C20H20ClNO2: C, 70.27; H, 5.90; N, 4.10. Found: C,
70.22; H, 5.94; N, 4.05.
endo-5a,5b,6,7,8,12b-Hexahydro-11-chloroindeno[2,3-c]pyrro-
lo[1,2-a]quinolin-8-one (endo-5k)
Colorless needles; mp 176–177 °C.
1H NMR (CDCl3): d = 1.91–2.07 (m, 1 H), 2.21–2.30 (m, 1 H),
2.58–2.67 (m, 2 H), 2.83–2.90 (m, 2 H), 3.07–3.18 (m, 1 H, H-4),
4.24 (dt, J = 7.8, 3.0 Hz, 1 H, H-3a), 4.34 (d, J = 7.8 Hz, 1 H, H-5),
Synthesis 2006, No. 12, 2053–2063 © Thieme Stuttgart · New York

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Diels–Alder Reactions of N-Acyliminium Cations with Olefins
2063
7.10 (dd, J = 9.0, 2.4 Hz, 1 H, H-8), 7.16–7.26 (m, 3 H, ArH), 7.40
(d, J = 2.4 Hz, 1 H, H-6), 7.52 (d, J = 6.9 Hz, 1 H, ArH), 8.45 (d,
J = 9.0 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 21.4 (C-3), 30.5 (CH2), 31.7 (C-5), 44.6 (C-
2), 46.2 (C-4), 57.4 (C-3a), 121.0 (C-9), 124.9 (C-8), 125.0 (CH),
126.7 (CH), 127.0 (CH), 127.6 (CH), 128.7 (C-6), 129.3 (C-7),
130.1 (C-5a), 134.5 (C-9a), 141.6 (C), 144.8 (C), 173.6 (C-1).
MS (EI): m/z (%) = 311 (6) [M + 2]+, 309 (17), 294 (1), 292 (3), 256
(3), 254 (11), 220 (3), 218 (12), 211 (7), 209 (22), 129 (11), 127
(50), 86 (29), 55 (100).
Ger. Offen. DE 4032090, 1991; Chem. Abstr. 1991, 115,
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Fang, W. J. Org. Chem. 2000, 65, 7158. (c) Pearson, W. H.;
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Org. Lett. 2003, 5, 3655. (b) Deady, L. W.; Werden, D. M.
J. Org. Chem. 1987, 52, 3930. (c) Eicher, T.; Rohde, R.
Synthesis 1985, 619. (d) Yakushijin, K.; Tsuruta, T.;
Furukawa, H. Chem. Pharm. Bull. 1982, 30, 140.
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The Alkaloids, Vol. 32; Brossi, A., Ed.; Academic Press:
New York, 1988, 271. (c) Hiemstra, H.; Speckamp, W. N.
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Fleming, I., Eds.; Pergamon: Oxford, 1991, 1047–1082.
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1988, 227.
Anal. Calcd for C19H16ClNO: C, 73.66; H, 5.21; N, 4.52. Found: C,
73.65; H, 5.24; N, 4.47.
exo-5a,5b,6,7,8,12b-Hexahydro-11-chloroindeno[2,3-c]pyrro-
lo[1,2-a]quinolin-8-one (exo-5k)
Colorless needles; mp 132–133 °C.
1H NMR (CDCl3): d = 1.73–1.85 (m, 1 H), 2.29–2.41 (m, 1 H),
2.46–2.57 (m, 2 H), 2.82 (d, J = 16.2 Hz, 1 H, CHH), 3.28 (dd,
J = 16.2, 6.6 Hz, 1 H, CHH), 3.35–3.43 (m, 1 H, H-3a), 4.34 (d,
J = 6.0 Hz, 1 H, H-5), 7.16–7.29 (m, 5 H, ArH), 7.48 (d, J = 2.4 Hz,
1 H, H-6), 8.63 (d, J = 9.0 Hz, 1 H, H-9).
13C NMR (CDCl3): d = 23.7 (CH2), 31.7 (CH2), 34.0 (C-5), 43.9 (C-
2), 46.6 (C-4), 56.2 (C-3a), 120.9 (C-9), 123.8 (CH), 125.5 (C-8),
126.8 (CH), 127.2 (CH), 127.9 (C-7), 128.5 (C-5a), 129.7 (C-6),
134.5 (C-9a), 139.8 (C), 144.0 (C), 173.6 (C-1).
MS (EI): m/z (%) = 311 (13) [M + 2]+, 309 (34), 294 (2), 292 (3),
276 (2), 274 (7), 256 (5), 254 (18), 220 (8), 218 (23), 192 (9), 190
(27), 88 (6), 86 (22), 55 (100).
Anal. Calcd for C19H16ClNO: C, 73.66; H, 5.21; N, 4.52. Found: C,
73.61; H, 5.26; N, 4.42.
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Acknowledgment
We thank the National Natural Science Foundation of China
(20472027 and QT Program) for financial support.
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Synthesis 2006, No. 12, 2053–2063 © Thieme Stuttgart · New York