Gold(I)-catalyzed tandem transformation: A simple approach for the synthesis of pyrrolo/pyrido[2,1- a ][1,3]benzoxazinones and pyrrolo/pyrido[2,1- a ]quinazolinones

Article abstract of DOI:10.1021/jo100228u

We have developed a simple method for the synthesis of pyrrolo/pyrido[2,1- a][1,3]benzoxazinones and pyrrolo/pyrido[2,1-a]quinazolinones from 2-amino benzoic acids and 2-amino benzamides via a gold(I)-catalyzed tandem coupling/cyclization process. The tricyclic or polycyclic molecular architectures were constructed in one pot with the formation of three new bonds.

Full text of DOI:10.1021/jo100228u

pubs.acs.org/joc
Gold(I)-Catalyzed Tandem Transformation: A Simple Approach for the
Synthesis of Pyrrolo/Pyrido[2,1-a][1,3]benzoxazinones and
Pyrrolo/Pyrido[2,1-a]quinazolinones
Enguang Feng, Yu Zhou, Dengyou Zhang, Lei Zhang, Haifeng Sun,
Hualiang Jiang, and Hong Liu*
State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica,
Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
hliu@mail.shcnc.ac.cn
Received February 17, 2010
We have developed a simple method for the synthesis of pyrrolo/pyrido[2,1-a][1,3]benzoxazinones
and pyrrolo/pyrido[2,1-a]quinazolinones from 2-amino benzoic acids and 2-amino benzamides via
a gold(I)-catalyzed tandem coupling/cyclization process. The tricyclic or polycyclic molecular archi-
tectures were constructed in one pot with the formation of three new bonds.
Introduction
gold-catalyzed reactions emerged as a powerful tool and were
applied in broad reactions, such as the nucleophilic addition,1
Friedel-Crafts reaction,2 C-H activation,3 hydrogenation,4
oxidation,5 and so on. Heterocyclic compounds, especially
some fused heterocycles, are considered as “privileged struc-
tures”6 and play very important roles in the pharmaceutical
and agrochemical industries. Therefore, the development
of new and effective strategies for the synthesis of these
fused heterocycles is being actively pursued for obtaining novel
Gold catalysts are considered to be attractive reagents in
organic synthesis for converting simple starting materials
into diverse and valuable synthetic products. In recent years,
(1) For selected examples of gold-catalyzed nucleophilic addition, see:
(a) Gorin, D. J.; Davis, N. R.; Toste, F. D. J. Am. Chem. Soc. 2005, 127,
11260. (b) Morita, N.; Krause, N. Org. Lett. 2004, 6, 4121. (c) Zhang, Z. B.;
Bender, C. F.; Widenhoefer, R. A. Org. Lett. 2007, 9, 2887. (d) Nishina, N.;
Yamamoto, Y. Angew. Chem., Int. Ed. 2006, 45, 3314. (e) Nishina, N.;
Yamamoto, Y. Synlett 2007, 1767.
(2) For selected examples of gold-catalyzed Friedel-Crafts reaction, see:
(a) Hashmi, A. S. K.; Schwarz, L.; Choi, J. H.; Frost, T. M. Angew. Chem.,
Int. Ed. 2000, 39, 2285. (b) Hashmi, A. S. K.; Blanco, M. C. Eur. J. Org.
Chem. 2006, 4340. (c) Nguyen, R. V.; Yao, X. Q.; Li, C. J. Org. Lett. 2006, 8,
2397. (d) Reich, N. W.; Yang, C. G.; Shi, Z. J.; He, C. Synlett 2006, 1278.
(3) Forselectedexamplesofgold-catalyzedC-H activation, see: (a) Hashmi,
A. S. K.; Schafer, S.; Wolfle, M.; Gil, C. D.; Fischer, P.; Laguna, A.; Blanco,
M. C.; Gimeno, M. C. Angew. Chem., Int. Ed. 2007, 46, 6184. (b) Wei, C. M.; Li,
C. J. J. Am. Chem. Soc. 2003, 125,9584. (c)Yao, X. Q.;Li, C.J.Org. Lett. 2006, 8,
1953. (d) Skouta, R.; Li, C. J. Angew. Chem., Int. Ed. 2007, 46, 1117.
(4) For selected examples of gold-catalyzed hydrogenation, see: (a) Zhang,
X.; Shi, H.; Xu, B. Q. Angew. Chem., Int. Ed. 2005, 44, 7132. (b) Comas-Vives,
A.; Gonzalez-Arellano, C.; Corma, A.; Iglesias, M.; Sanchez, F.; Ujaque, G.
J.Am. Chem. Soc. 2006, 128, 4756. (c) Astruc, D.; Lu, F.;Aranzaes,J. R. Angew.
Chem., Int. Ed. 2005, 44, 7852.
(5) For selected examples of gold-catalyzed oxidation, see: (a) Haruta,
M. Nature 2005, 437, 1098. (b) Hughes, M. D.; Xu, Y. J.; Jenkins, P.;
McMorn, P.; Landon, P.; Enache, D. I.; Carley, A. F.; Attard, G. A.;
Hutchings, G. J.; King, F.; Stitt, E. H.; Johnston, P.; Griffin, K.; Kiely,
C. J. Nature 2005, 437, 1132. (c) Nijhuis, T. A. R.; Visser, T.; Weckhuysen,
B. M. Angew. Chem., Int. Ed. 2005, 44, 1115. (d) Christensen, C. H.; Jorgensen,
B.; Rass-Hansen, J.; Egeblad, K.; Madsen, R.; Klitgaard, S. K.; Hansen, S. M.;
Hansen, M. R.; Andersen, H. C.; Riisager, A. Angew. Chem., Int. Ed. 2006, 45,
4648. (e) Gonzalez-Arellano, C.; Corma, A.; Iglesias, M.; Sanchez, F. Chem.
Commun. 2005, 1990.
(6) For selected reviews, see: (a) Clement, N. D.; Cavell, K. J. Angew.
Chem., Int. Ed. 2004, 43, 3845. (b) Nakamura, I.; Yamamoto, Y. Chem. Rev.
2004, 104, 2127. (c) Patil, N. T.; Yamamoto, Y. Chem. Rev. 2008, 108, 3395.
(d) Evano, G.; Blanchard, N.; Toumi, M. Chem. Rev. 2008, 108, 3054.
3274 J. Org. Chem. 2010, 75, 3274–3282
Published on Web 04/28/2010
DOI: 10.1021/jo100228u
r
2010 American Chemical Society

Feng et al.
JOCArticle
SCHEME 1. Proposed One-Pot Synthesis of Pyrrolo/
Pyrido[1,2-a][3,1]benzoxazinones
TABLE 1. Optimization of Reaction Conditions of the Tandem
Synthesis of 3Aaa
entry
catalyst system
temp (°C)
solvent
yield (%)
1
2
3
4
5
6
7
8
AuCl3
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
100
DCE
DCE
DCE
DCE
DCE
DCE
DCE
toluene
DME
DCM
DMF
H2O
dioxane
THF
DCE
DCE
DCE
DCE
DCE
DCE
56
0
50
30
56
60
AuBr3
AuI
AuCl(PPh3)
Au1 catalyst
Au2 catalyst
Au2 catalyst
Au2 catalyst
Au2 catalyst
Au2 catalyst
Au2 catalyst
Au2 catalyst
Au2 catalyst
Au2 catalyst
AgSbF6
95/95b
86b
71b
85b
30b
0b
9
10
11
12
13
14
15
16
17
18
19
20
64b
75b
85c
41d/85e
93b
92b
80f
75b
bioactive lead compounds.7 To this end, transition-metal-cat-
alyzed domino reactions, which allow the formation or cleavage
of multiple bonds in one synthetic operation, have been used
for the preparation of various compounds. However, the
majority of reported gold-catalyzed cascade sequences involve
the intramolecular reaction of a single starting compound that
contains multiple functional groups strategically positioned
along a chain, terminating with alkyne functionality. In addi-
tion, the rapid and convenient synthesis of complex and diverse
organic molecules in a one-pot operation/reaction remains one
of the most important concerns of the chemistry community.8
Recently, we successfully achieved the gold-catalyzed tan-
dem transformation of pyrrolo[1,2-a]quinolin-1(2H)-ones9
and pyrrolo/pyrido[2,1-b]benzo[d][1,3]oxazin-1-ones.10 Herein,
we describe a simple and efficient one-pot gold-catalyzed
cascade coupling/cyclization reaction for the synthesis of pyrrolo/
pyrido[2,1-a][1,3]benzoxazinones and pyrrolo/pyrido[2,1-a]-
quinazolinones by a gold-catalyzed cascade coupling/cyclization
process. To the best of our knowledge, this is the first report
of the formation of pyrrolo/pyrido[2,1-a][1,3]benzoxazinones
and pyrrolo/pyrido[2,1-a]quinazolinones via a transition-
metal-catalyzed domino reaction.
Au2 catalyst/AgSbF6
Au2 catalyst/TFA
Au2 catalyst
Au2 catalyst
aReaction conditions: 1A (0.1 mmol), 2a (0.15 mmol), and Au catalyst
(1.5 mol %) in solvent (2.0 mL), oil bath for 12 h under argon protection.
Au1 catalyst=[Au{P(t-Bu)2(o-biphenyl)}]Cl; Au2 catalyst=[Au{P(t-Bu)2-
(o-biphenyl)} {CH3CN}]SbF6. bReaction performed without argon pro-
tection. cReaction performed in the presence of 0.5 mol % Au2 catalyst
and without argon protection. dReaction performed in the presence of
1.5 mol % AgSbF6. eReaction performed in the presence of 10 mol %
AgSbF6. fReaction performed for 6 h without argon protection.
activated enol-lactone intermediate A.11 Subsequently, the
amino group of 2-amino benzoic acids 1 attacks this inter-
mediate to form ammonolysis products. In the presence of
an appropriate gold catalyst, the resulting ketoamide B
might be converted into the transition-state complex C via
N-acyliminium ion formation/cyclization.12 Finally, nucleo-
philic attack by the hydroxyl group could yield the final
product 3.
Our proposed approach is summarized in Scheme 1. Alkynoic
acids are first activated by a gold(I) catalyst to afford cyclic
Results and Discussion
In the preliminary experiments, we selected 2-amino ben-
zoic acid 1A and 4-pentynoic acid 2a as the model substrates.
The initial reactions were carried out in dichloroethane (DCE)
using AuCl3 (1.5 mol %) as the catalyst at 120 °C in a sealed
tube under argon atmosphere. The starting materials were
completely consumed, and the expected product 3Aa was
obtained in a moderate yield after 12 h (Table 1, entry 1),
whereas the reaction did not proceed in the absence of gold
catalysts (Table 1, entry 2). [Au{P(t-Bu)2(o-biphenyl)}{CH3-
CN}]SbF6 (Au2 catalyst) turned out to be better than the other
gold catalysts, such as AuI, AuBr3, AuCl(PPh3), and [Au-
{P(t-Bu)2(o-biphenyl)}]Cl(Au1 catalyst) (Table 1, entries 3-7).
Furthermore, unlike the air- and water-sensitive AuI and
AuBr3, the reaction carried out with Au2 catalyst afforded
(7) For selected examples, see: (a) Murata, Y.; Yamashita, D.; Kitahara,
K.; Minasako, Y.; Nakazaki, A.; Kobayashi, S. Angew. Chem., Int. Ed. 2009,
48, 1400. (b) Barluenga, J.; Mendoza, A.; Rodriguez, F.; Fananas, F. J.
Angew. Chem., Int. Ed. 2009, 48, 1644. (c) Zhao, Y. B.; Mariampillai, B.;
Candito, D. A.; Laleu, B.; Li, M. Z.; Lautens, M. Angew. Chem., Int. Ed.
2009, 48, 1849. (d) Bender, C. F.; Yoshimoto, F. K.; Paradise, C. L.;
De Brabander, J. K. J. Am. Chem. Soc. 2009, 131, 11350. (e) Wu, X. X.;
Zhou, J. Y.; Snider, B. B. Angew. Chem., Int. Ed. 2009, 48, 1283.
(8) For selected reviews, see: (a) Enders, D.; Grondal, C.; Huttl, M. R. M.
Angew. Chem., Int. Ed. 2007, 46, 1570. (b) Tietze, L. F. Chem. Rev. 1996, 96,
115.
(9) Zhou, Y.; Feng, E. G.; Liu, G. N.; Ye, D. J.; Li, J.; Jiang, H. L.; Liu, H.
J. Org. Chem. 2009, 74, 7344.
(10) Zhou, Y.; Zhai, Y.; Ji, X.; Liu, G. N.; Feng, E. G.; Ye, D. J.; Zhao,
L. X.; Jiang, H. L.; Liu, H. Adv. Synth. Catal. 2010, 352, 373.
(11) (a) Genin, E.; Toullec, P. Y.; Antoniotti, S.; Brancour, C.; Genet, J. P.;
Michelet, V. J. Am. Chem. Soc. 2006, 128, 3112. (b) Harkat, H.; Weibel, J.-M.;
Pale, P. Tetrahedron Lett. 2006, 47, 6273. (c) Muratore, M. E.; Holloway, C. A.;
Pilling, A. W.; Storer, R. I.; Trevitt, G.; Dixon, D. J. J. Am. Chem. Soc. 2009, 131,
10796.
(12) Liu, X. Y.; Che, C. M. Angew. Chem., Int. Ed. 2008, 47, 3805.
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SCHEME 2. Reaction of the Enol-lactone Intermediate A with
2-Amino Benzoic acid 1A
Subsequently, we investigated whether the protocol can be
extended to the reaction of 2-amino benzamides 4 with
alkynoic acids 2. As shown in Table 3, the desired products,
pyrrolo/pyrido[2,1-a]quinazolinones 5, were obtained in good
yields. Alkyl- and aryl-substituted 2-amino benzamides, which
were prepared from the corresponding 2-amino benzoic acids,13
were efficiently converted into their corresponding products in
high yields (Table 3, entries1-4). As shown in Table 2, sub-
stituents with both electron-donating groups (5-OCH3, 5-CH3)
and electron-withdrawing groups (5-Cl) were successfully con-
verted to the products (Table 3, entries 5-8). Similarly, good
yields were obtained when 4-pentynoic acid was replaced with
5-hexynoic acid (2b) (Table 3, entries 9, 10, 12, and 13).
However, steric effect was significant when 2-amino-N-(sec-
butyl) benzamide (4C) was treated with 5-hexynoic acid (2b)
(Table 3, entry 11). The substitution of an alkyl group (n-hexyl
group) at the alkynoic acid chain was also tolerated, and
excellent yields were obtained (Table 3, entries 14-17).
3Aa in high yield even without argon protection. This con-
firmed that the reaction system was not sensitive to air and
moisture at low catalyst loadings (Table 1, entry 7). Subse-
quently, probing solvent effect revealed that DCE was supe-
rior to the others (Table 1, entries 8-14). However, the product
yield obtained with 0.5 mol % Au2 catalyst was slightly lower
than that obtained with 1.5 mol % Au2 catalyst (Table 1,
entry 15). A lower yield was obtained when AgSbF6 (1.5 mol %)
was tested for this reaction, and the yield increased to 85%
when 10 mol % AgSbF6 was used (Table 1, entry 16). Further-
more, it was determined whether acids such as AgSbF6 and
trifluoroacetic acid (TFA), respectively, could be used as
cocatalysts to increase the speed of the reaction; however,
reactions carried out using these acids as the cocatalyst did
not give better results than that using Au2 catalyst only
(Table 1, entries 17 and 18). Finally, reducing the reaction
time (6 h) or decreasing the reaction temperature led to worse
results (Table 1, entries 19 and 20). Briefly, the optimum
results were obtained when 2-amino benzoic acid (0.1 mmol,
1A) and 4-pentynoic acid (0.15 mmol, 2a) in DCE were
treated with 1.5 mol % of Au2 catalyst in a sealed tube at
120 °C for 12 h.
Conclusion
In summary, a facile and practical protocol for the synthe-
sis of pyrrolo/pyrido[2,1-a][1,3]benzoxazinones and pyrrolo/
pyrido[2,1-a]quinazolinones was developed via a gold(I)-
catalyzed tandem coupling/cyclization. Three new bonds
were formed from two simple starting materials in this trans-
formation. A plausible reaction mechanism based on the results
was also described. Using this method, a variety of products
could be conveniently synthesized in good to excellent yields.
We expect these novel molecules to find several applications
in medicinal chemistry and/or agrochemistry.
To further explore the proposed mechanism, we have
treated one of the commercially available intermediates A
(R-angelica lactone) from Scheme 1 with 2-amino benzoic
acid 1A under the above optimal reaction conditions, and the
desired product 3Aa was obtained in 91% yield (Scheme 2).
With the optimal conditions established, we then investi-
gated the scope of this method. First, we examined the reac-
tions of various substituted 2-amino benzoic acids 1 with 2a
(Table 2, entries 1-14). 2-Amino benzoic acids bearing both
electron-withdrawing (4-F, 6-F, 4-Cl, 5-Cl, and 5-NO2) and
electron-donating groups (3-CH3 and 5-CH3, 4,5-dimethoxy,
3,4-dimethyl) appeared to be reactive and afforded the pro-
ducts in good to excellent yields (Table 2, entries 2-11). It is
worthwhile to note that the unprotected phenolic hydroxyl
group was also tolerated in the reaction (Table 2, entry 9).
Substitution at the 5-position of 2-amino benzoic acids
helped achieve high yields of the product. However, treat-
ment of 3-amino-2-naphthoic acid (1M) resulted in a de-
crease of yield (65%), and more reaction time (24 h) was
required (Table 2, entry 13). In addition, owing to the poor
solubility of 2-amino nicotinic acid (1N) in DCE, the product
was obtained in a low yield even when the reaction time was
extended to 24 h (Table 2, entry 14). Furthermore, the
replacement of 4-pentynoic acid with 5-hexynoic acid (2b)
also achieved good yields (Table 2, entries15-17). Substitu-
tion of an alkyl group (n-hexyl group) with an alkynoic acid
chain afforded the product in excellent yields (Table 2,
entries 18-20). The product 3Ha was recrystallized from a
component solvent of petroleum ether and ethyl acetate and
characterized with crystallography (see Supporting Informa-
tion for details).
Experimental Section
General Procedure for Synthesis of Pyrrolo/Pyrido[2,1-a][1,3]-
benzoxazinones and Pyrrolo/Pyrido[2,1-a]quinazolinones. To a
solution of 2-amino benzoic acids or 2-amino benzamides (0.1 mmol)
and alkynoic acids (0.15 mmol) in DCE (2.0 mL) was added Au2
catalyst ([Au{P(t-Bu)2(o-biphenyl)}{CH3CN}]SbF6, 1.5 mol %).
The vial was sealed, and this mixture was then heated in an oil
bath and stirred at 120 °C for 12-24 h. After the starting mate-
rials were consumed monitored with TLC, the cold mixture was
concentrated in a vacuum, and the resulting residue was purified
by flash column chromatography (petroleum ether (PE)/ethyl
acetate (EA)=4:1 to 1:1) to afford the expected tricyclic hetero-
cyclic products. For a selected example, compound 3Aa, the
characterization data obtained are as follows: white solid, mp
115-117 °C. 1H NMR (CDCl3, 300 MHz) δ 1.66 (s, 3H), 2.40-
2.73 (m, 4H), 7.29 (td, J=7.8 Hz, 0.9 Hz, 1H), 7.86 (td, J=7.8 Hz,
0.9 Hz, 1H), 8.01 (d, J=7.8 Hz, 1H), 8.06 (dd, J=7.8 Hz, 1.2
Hz, 1H); 13C NMR (CDCl3, 100 MHz) δ 24.6, 29.3, 32.2, 95.2,
116.1, 120.9, 125.6, 130.2, 135.2, 136.0, 161.5, 171.5; ESI-MS
m/z [M þ H]þ 217.9; HRMS (ESI) calcd for C12H11NO3Na
[M þ Na]þ 240.0637, found 240.0648.
6-Fluoro-3a-methyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Ba). Compound 3Ba was obtained as a
white solid after the purification by flash chromatography (PE/
EA=4:1), mp 139-140 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.73 (s, 3H), 2.42-2.78 (m, 4H), 7.07 (t, J=9 Hz, 1H), 7.66 (td,
J=8.4 Hz, 5.1 Hz, 1H), 7.88 (d, J=8.4 Hz, 1H); 13C NMR (100
MHz, CDCl3, ppm) δ 24.6, 27.5, 32.1, 95.2, 114.0 (d, 20.9 Hz,),
117.1 (d, 3.8 Hz), 136.5 (d, 112 Hz), 137.3, 161.4, 164.1, 171.7;
(13) Mizutani, T.; Nagase, T.; Ito, S.; Miyamoto, Y.; Tanaka, T.;
Takenaga, N.; Tokita, S.; Sato, N. Bioorg. Med. Chem. Lett. 2008, 18, 6041.
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TABLE 2. One-Pot Tandem Synthesis of 3 from 2-Amino Benzoic Acids 1 and Alkynoic Acids 2a
aReaction conditions: 1(0.1 mmol), 2(0.15 mmol) and Au2 catalyst(1.5mol%) inDCE(2.0mL) at120°C for 12 h. bThe reaction time was prolonged to 24 h.
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TABLE 3. One-Pot Tandem Synthesis of 5 from 2-Amino Benzamides 4 and Alkynoic Acids 2a
aReaction conditions: 1 (0.1 mmol), 2 (0.15 mmol) and Au2 catalyst (1.5 mol %) in DCE (2.0 mL) at 120 °C for 12 h.
ESI-MS m/z [M þ H]þ 235.9; HRMS (ESI) calcd for C12H10-
FNO3Na [M þ Na]þ 258.0542, found 258.0549.
(PE/EA=4:1), mp 51-53 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.69 (s, 3H), 2.44-2.75 (m, 4H), 7.00 (td, J = 8.1 Hz, 2.4 Hz,
1H), 7.84 (dd, J=9.6 Hz, 2.4 Hz, 1H), 8.11 (dd, J=8.7 Hz, 6 Hz,
1H); 13C NMR (100 MHz, CDCl3, ppm) δ 24.6, 29.4, 32.3, 95.3,
108.2 (d, 26.8 Hz), 112.1, 113.4 (d, 22.3 Hz), 133.1 (d, 10.4 Hz),
8-Fluoro-3a-methyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Ca). Compound 3Ca was obtained
as a white solid after purification by flash chromatography
3278 J. Org. Chem. Vol. 75, No. 10, 2010

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138.0 (d, 12.6 Hz), 160.8, 166.8(d, 255.9 Hz), 171.3; MS (EI) m/e
235; HRMS (EI) m/e (Mþ) calcd for C12H10FNO3 235.0645,
found 235.0636.
29.5, 32.2, 56.1, 56.4, 95.3, 103.3, 107.8, 110.7, 131.5, 146.8,
154.9, 161.6, 171.4; ESI-MS m/z [M þ H]þ 277.9; HRMS (ESI)
calcd for C14H15NO5Na [M þ Na]þ 300.0848, found 300.0835.
3a,8,9-Trimethyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Ka). Compound 3Ka was obtained as a
white solid after purification by flash chromatography (PE/
EA=4:1), mp 158-159 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.64 (s, 3H), 2.22 (s, 3H), 2.35-2.42 (m, 1H), 2.40 (s, 3H),
2.63-2.77 (m, 3H), 7.23 (d, J=7.8 Hz, 1H), 7.85 (d, J=7.8 Hz,
1H); 13C NMR (100 MHz, CDCl3, ppm) δ 15.1, 20.9, 25.1, 28.9,
31.7, 96.9, 118.1, 127.4, 128.9, 133.4, 135.2, 145.9, 162.7, 174.9;
ESI-MS m/z [M þ H]þ 245.9; HRMS (ESI) calcd for
C14H15NO2Na [M þNa]þ 268.0950, found 268.0942.
7-Chloro-3a-methyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Da). Compound 3Da was obtained as a
white solid after purification by flash chromatography (PE/
EA=4:1), mp 117-118 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.70 (s, 3H), 2.44-2.77 (m, 4H), 7.64 (dd, J = 8.7 Hz, 3 Hz,
1H), 8.06 (d, J=8.7 Hz, 1H), 8.09 (d, J=2.4 Hz, 1H); 13C NMR
(100 MHz, CDCl3, ppm) δ 24.7, 29.4, 32.3, 95.5, 117.5, 122.5,
130.0, 131.4, 134.6, 135.5, 160.5, 171.5; ESI-MS m/z [M þ H]þ
251.9; HRMS (ESI) calcd for C12H10ClNO3Na [M þ Na]þ
274.0247, found 274.0242.
8-Chloro-3a-methyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Ea). Compound 3Ea was obtained
as a white solid after purification by flash chromatography
(PE/EA = 4:1), mp 158-160 °C. 1H NMR (300 MHz, CDCl3,
ppm) δ 1.70 (s, 3H), 2.44-2.78 (m, 4H), 7.31 (dd, J=8.1 Hz, 2.4
Hz, 1H), 8.04 (d, J=8.1 Hz, 1H), 8.13 (d, J=2.4 Hz, 1H); 13C
NMR (100 MHz, CDCl3, ppm) δ 24.7, 29.4, 32.3, 95.4, 114.3,
121.0, 126.2, 131.6, 136.9, 142.0, 160.9, 171.4; MS (EI) m/e 251
HRMS (EI) m/e (Mþ) calcd for C12H10ClNO3 251.0349, found
251.0343.
9-Bromo-3a,7-dimethyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-
b][1,3]oxazine-1,5(2H)-dione (3La). Compound 3La was obta-
ined as a white solid after purification by flash chromatography
(PE/EA = 4:1), mp 208-209 °C. 1H NMR (300 MHz, CDCl3,
ppm) δ 1.64 (s, 3H), 2.35-2.46 (m, 1H), 2.40 (s, 3H), 2.61-2.74
(m, 3H), 7.71 (d, J =0.9 Hz, 1H), 7.85 (d, J = 0.9 Hz, 1H);13C
NMR (100 MHz, CDCl3, ppm) δ 20.7, 24.8, 28.6, 31.5, 97.3,
119.3, 122.0, 129.5, 133.8, 139.2, 139.6, 161.4, 173.9; ESI-MS
m/z [M þ H]þ 309.8; HRMS (ESI) calcd for C13H12BrNO3Na
[M þ Na]þ 331.9898, found 331.9896.
3a-Methyl-7-nitro-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Fa). Compound 3Fa was obtained
as a white solid after purification by flash chromatography
(PE/EA = 4:1), mp 177-179 °C. 1H NMR (300 MHz, CDCl3,
ppm) δ 1.73 (s, 3H), 2.52-2.82 (m, 4H), 8.38 (d, J = 9 Hz, 1H),
8.52 (dd, J=9 Hz, 2.4Hz, 1H), 8.98 (d, J=2.7Hz, 1H);13C NMR
(100 MHz, CDCl3, ppm) δ 24.8, 29.5, 32.4, 92.3, 116.2, 121.3,
126.3, 130.2, 140.7, 144.5, 159.6, 171.3; MS (EI) m/e 262 HRMS
(EI) m/e (Mþ) calcd for C12H10N2O5 262.0590, found 262.0587.
3a,7-Dimethyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Ga). Compound 3Ga was obtained as
a white solid after purification by flash chromatography (PE/
EA=4:1), mp 135-136 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.68 (s, 3H), 2.38-2.47 (m, 4H), 2.66-2.76 (m, 3H), 7.49 (dd,
J=8.4 Hz, 1.8 Hz, 1H), 7.90 (d, J=1.8 Hz, 1H), 7.93 (d, J=8.4Hz,
1H); 13C NMR (100 MHz, CDCl3, ppm) δ 20.9, 24.7, 29.4, 32.3,
95.4, 116.1, 121.0, 130.4, 133.7, 135.8, 136.3, 161.9, 171.6; ESI-
MS m/z [MþH]þ 231.9; HRMS (ESI) calcd for C13H13NO3Na
[M þNa]þ 254.0793, found 254.0795.
3a-Methyl-3,3a-dihydro-1H-naphtho[2,3-d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Ma). Compound 3Ma was obtained as
a white solid after purification by flash chromatography (PE/
EA=4:1), mp 244-245 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.72 (s, 3H), 2.44-2.51 (m, 1H), 2.62-2.81 (m, 3H), 7.51-7.67
(m, 2H), 7.89-7.97 (m, 2H), 8.44 (s, 1H), 8.72 (s, 1H); 13C NMR
(100 MHz, CDCl3, ppm) δ 25.5, 29.4, 32.1, 95.5, 115.5, 119.3,
126.7, 127.8, 129.6, 129.7, 130.3, 130.9, 133.0, 136.5, 162.1,
171.5; MS (EI) m/e 267 HRMS (EI) m/e (Mþ) calcd for
C16H13NO3 267.0895, found 267.0891.
6a-Methyl-7,8-dihydro-5H-pyrido[2,3-d]pyrrolo[2,1-b][1,3]-
oxazine-5,9(6aH)-dione (3Na). Compound 3Na was obtained as
a white solid after purification by flash chromatography (PE/
EA=4:1), mp 196-197 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.72 (s, 3H), 2.42-2.51 (m, 1H), 2.59-2.69 (m, 1H), 2.73-2.82
(m, 2H), 7.36 (dd, J=7.8 Hz, 2.4 Hz, 1H), 8.42 (d, J=7.5 Hz,
1H), 8.82 (d, J = 4.8 Hz, 1H); 13C NMR (100 MHz, CDCl3,
ppm) δ 25.2, 29.6, 32.1, 95.9, 112.8, 121.8, 139.3, 148.9, 155.0,
161.2, 171.4; ESI-MS m/z [M þ H]þ 218.9; HRMS (ESI) calcd
for C11H10N2O3Na [M þNa]þ 241.0589, found 241.0594.
4a-Methyl-2,3,4,4a-tetrahydrobenzo[d]pyrido[2,1-b][1,3]oxazine-
1,6-dione (3Ab). Compound 3Ab was obtained as a white solid
after purification by flash chromatography (PE/EA=4:1), mp
3a,9-Dimethyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Ha). Compound 3Ha was obtained as a
white solid after purification by flash chromatography (PE/
EA=4:1), mp 140-142 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.63 (s, 3H), 2.33-2.43 (m, 1H), 2.35 (s, 3H), 2.62-2.76 (m,
3H), 7.33 (t, J=7.8 Hz, 1H), 7.54 (d, J=7.8 Hz, 1H), 7.92 (d, J=
7.8 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm) δ 18.2, 25.0,
28.8, 31.7, 96.8, 120.4, 127.2, 127.6, 134.8, 135.4, 137.0, 162.5,
174.7; ESI-MS m/z [M þ H]þ 232.0; HRMS (ESI) calcd for
C13H13NO3Na [M þ Na]þ 254.0793, found 254.0802.
1
66-68 °C. H NMR (300 MHz, CDCl3, ppm) δ 1.61 (s, 3H),
1.84-1.90 (m, 1H), 2.10-2.17 (m, 2H), 2.39-2.43 (m, 1H),
2.60-2.65 (m, 2H), 7.35 (t, J=7.5 Hz, 1H), 7.64 (t, J=7.5 Hz,
1H), 7.78 (d, J=7.5 Hz, 1H), 8.06 (d, J=7.5 Hz, 1H); 13C NMR
(100 MHz, CDCl3, ppm) δ 16.6, 26.7, 33.4, 36.0, 92.4, 120.3,
126.2, 126.3, 129.3, 134.1, 138.5, 162.5, 169.4; ESI-MS m/z
[M þ Na]þ 231.9; HRMS (ESI) calcd for C13H13NO3Na [M þ
Na]þ 254.0793, found 254.0785.
7-Hydroxy-3a-methyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b]-
[1,3]oxazine-1,5(2H)-dione (3Ia). Compound 3Ia was obtained
as a white solid after purification by flash chromatography (PE/
EA=4:1), mp 173-174 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.67 (s, 3H), 2.40-2.75 (m, 4H), 7.19 (dd, J = 9 Hz, 2.4 Hz,
1H), 7.56 (d, J=2.4 Hz, 1H), 7.83 (d, J=9 Hz, 1H); 13C NMR
(100 MHz, CDCl3, ppm) δ 24.7, 29.3, 32.1, 96.1, 115.8, 117.5,
123.0, 126.4, 128.7, 154.5, 162.2, 172.2; ESI-MS m/z [M þ H]þ
233.9; HRMS (ESI) calcd for C12H11NO4Na [M þ Na]þ
256.0586, found 256.0598.
8-Chloro-4a-methyl-2,3,4,4a-tetrahydrobenzo[d]pyrido[2,1-b]-
[1,3]oxazine-1,6-dione (3Db). Compound 3Db was obtained as a
white solid after purification by flash chromatography (PE/
EA=4:1), mp 102-103 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.64 (s, 3H), 1.85-1.91 (m, 1H), 2.07-2.22 (m, 2H), 2.40-2.47
(m, 1H), 2.61-2.67 (m, 2H), 7.60 (dd, J =8.7 Hz, 1.8 Hz, 1H),
7.77 (d, J=8.7 Hz, 1H), 8.04 (d, J=2.1 Hz, 1H); 13C NMR (100
MHz, CDCl3, ppm) δ 16.5, 26.7, 33.4, 35.9, 92.7, 127.6, 129.0,
132.0, 134.1, 137.0, 161.5, 169.4, 171.4; MS (EI) m/e 265; HRMS
(EI) m/e (Mþ) calcd for C13H12ClNO3 265.0506, found 265.0502.
4a,8-Dimethyl-2,3,4,4a-tetrahydrobenzo[d]pyrido[2,1-b][1,3]-
oxazine-1,6-dione (3Gb). Compound 3Gb was obtained as a white
solid after purification by flash chromatography (PE/EA = 4:1),
mp 119-121 °C. 1H NMR (300 MHz, CDCl3, ppm) δ 1.60 (s, 3H),
7,8-Dimethoxy-3a-methyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b]-
[1,3]oxazine-1,5(2H)-dione (3Ja). Compound 3Ja was obtained
as a white solid after purification by flash chromatography (PE/
EA=4:1), mp 146-147 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.66 (s, 3H), 2.38-2.72 (m, 4H), 3.90 (s, 3H), 3.96 (s, 3H), 7.45
(s, 1H), 7.58 (s, 1H); 13C NMR (100 MHz, CDCl3, ppm) δ 24.3,
J. Org. Chem. Vol. 75, No. 10, 2010 3279

Feng et al.
JOCArticle
1.82-1.88 (m, 1H), 2.04-2.20 (m, 2H), 2.32-2.44 (m, 1H), 2.40 (s,
3H), 2.58-2.64 (m, 2H), 7.44 (dd, J=8.4 Hz, 2.1 Hz, 1H), 7.66 (d,
J= 8.4 Hz, 1H), 7.85 (d, J= 2.1 Hz, 1H); 13C NMR (100 MHz,
CDCl3, ppm) δ 16.6, 20.9, 26.7, 33.4, 36.0, 92.4, 120.0, 125.9, 129.4,
135.0, 136.1, 136.3, 162.8, 169.4; ESI-MS m/z [M þ H]þ 245.9;
HRMS (ESI) calcd for C14H15NO3Na [MþNa]þ 268.0950, found
268.0966.
22.5, 26.1, 27.1, 29.0, 31.6, 31.8, 38.2, 40.6, 94.6, 117.5, 122.3,
130.2, 133.9, 136.0, 136.1, 162.3, 175.4; ESI-MS m/z [M þ H]þ
316.0; HRMS (ESI) calcd for C19H25NO3Na [MþNa]þ 338.1732,
found 338.1730.
3a-Methyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-1,5-
dione (4Aa). Compound 4Aa was obtained as a white solid after
purification by flash chromatography (PE/EA=1:1), mp 165-
167 °C. 1H NMR (300 MHz, CDCl3, ppm) δ 1.67(s, 3H),
2.37-2.42 (m, 2H), 2.68-2.74 (m, 2H), 7.28 (td, J = 7.8 Hz,
0.9 Hz, 1H), 7.60 (td, J=7.8 Hz, 1.8 Hz, 1H), 8.06 (dd, J=7.8
Hz, 1.8 Hz, 1H), 8.16 (d, J = 7.8 Hz, 1H), 8.28 (br, 1H); 13C
NMR (100 MHz, CDCl3, ppm) δ 26.9, 30.0, 32.9, 74.5, 119.5,
120.7, 125.0, 128.3, 133.8, 135.8, 163.5, 171.7; ESI-MS m/z
[M þ H]þ 217.0; HRMS (ESI) calcd for C12H12N2O2Na [M þ
Na]þ 239.0796, found 239.0796.
3a,4-Dimethyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-1,5-
dione (4Ba). Compound 4Ba was obtained as a white solid after
purification by flash chromatography (PE/EA = 1:1), mp 96-
97 °C. 1H NMR (300 MHz, CDCl3, ppm) δ 1.45 (s, 3H),
2.25-2.32 (m, 1H), 2.38-2.49 (m, 1H), 2.63-2.9 (m, 2H), 3.06
(s, 3H), 7.24 (t, J=7.5 Hz, 1H), 7.53 (t, J=7.5 Hz, 1H), 8.07 (d,
J=7.8 Hz, 1H), 8.25 (d, J=7.8 Hz, 1H);13C NMR (100 MHz,
CDCl3, ppm) δ 21.6, 27.6, 30.1, 32.2, 78.4, 119.2, 119.5, 124.8,
128.4, 133.2, 135.0, 161.9, 171.1; ESI-MS m/z [M þ H]þ 230.9;
HRMS (ESI) calcd for C13H14N2O2Na [M þ Na]þ 253.0953,
found 253.0958.
4-(sec-Butyl)-3a-methyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quina-
zoline-1,5-dione (4Ca). Compound 4Ca was obtained as a white
wax solid after purification by flash chromatography (PE/EA=
1:1), mp <50 °C, and the two diastereomers were inseparable by
chromatography. 1H NMR (300 MHz, CDCl3, ppm) δ 0.93 (q,
J = 7.5 Hz, 3H), 1.48-155 (m, 6H), 1.81-1.90 (m, 1H), 1.99-
2.07 (m, 1H), 2.30-2.50 (m, 2H), 2.61-2.66 (m, 2H), 3.14-3.23
(m, 1H), 7.22 (t, J=8.4 Hz, 1H), 7.50 (t, J=8.4 Hz, 1H), 8.00
(t, J=7.2 Hz, 1H), 8.20 (dd, J=8.1 Hz, 15 Hz, 1H); 13C NMR
(100 MHz, CDCl3, ppm) δ 12.0, 12.5, 18.0, 18.5, 24.3, 24.4, 27.5,
27.8, 30.0, 30.2, 32.2, 32.7, 54.5, 79.4, 119.2, 119.4, 121.0, 124.7,
124.8, 128.0, 128.1, 132.7, 132.8, 134.5, 134.7, 161.2, 171.0,
171.1; ESI-MS m/z [M þ H]þ 273.0; HRMS (ESI) calcd for
C16H20N2O2Na [M þNa]þ 295.1422, found 295.1406.
2-Hexyl-3a-methyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b][1,3]-
oxazine-1,5(2H)-dione (3Ac). Compound 3Ac was obtained after
purification by flash chromatography (PE/EA=4:1), and the two
diastereomers were separable by chromatography (dr = 1.4:1).
Diastereomer 1: white wax solid, mp <50 °C. 1H NMR (300 MHz,
CDCl3, ppm) δ 0.87-0.92 (m, 3H), 1.31-1.51 (m, 8H), 1.52-1.55
(m, 1H), 1.69 (s, 3H), 1.97-2.04 (m, 1H), 2.21-2.28 (m, 1H),
2.58-2.71 (m, 2H), 7.32 (td, J=8,7 Hz, 0.9 Hz, 1H), 7.69 (td, J=
8.1 Hz, 1.5 Hz, 1H), 8.11 (dd, J=8.1 Hz, 1.8 Hz, 1H), 8.17 (d, J=
8.4 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm) δ 14.0, 22.6, 24.4,
26.9, 29.0, 30.4, 31.6, 39.2, 40.7, 93.5, 115.6, 120.4, 125.4, 130.4,
135.5, 136.2, 161.6, 173.2; ESI-MS m/z [M þ H]þ 302.0; HRMS
(ESI) calcd for C18H23NO3Na [M þ Na]þ 324.1576, found
324.1584. Diastereomer 2: white wax solid, mp <50 °C. 1H NMR
(300 MHz, CDCl3, ppm) δ 0.88-0.92 (m, 3H), 1.32-1.57 (m, 9H),
1.72 (s, 3H), 1.97-2.16 (m, 2H), 2.80-2.85 (m, 2H), 7.37 (td, J=
7.8 Hz, 0.9 Hz, 1H), 7.71 (td, J=7.8 Hz, 1.5 Hz, 1H), 7.86 (d, J=
7.8 Hz, 1H), 8.02 (dd, J=7.8 Hz, 1.2 Hz, 1H); 13C NMR (100 MHz,
CDCl3, ppm) δ14.0, 22.5, 26.3, 27.2, 29.0, 31.6, 31.8, 38.2, 40.6, 94.6,
117.7, 122.5, 126.1, 130.2, 135.3, 136.3, 162.1, 175.4; ESI-MS m/z
[MþH]þ 302.0; HRMS (ESI) calcd for C18H23NO3Na [MþNa]þ
324.1576, found 324.1581.
7-Chloro-2-hexyl-3a-methyl-3,3a-dihydro-1H-benzo[d]pyrrolo-
[2,1-b][1,3]oxazine-1,5(2H)-dione (3Dc). Compound 3Dc was obta-
ined after purification by flash chromatography (PE/EA = 4:1),
and the two diastereomers were separable by chromatography
1
(dr = 1.5:1). Diastereomer 1: white wax solid, mp <50 °C. H
NMR (300 MHz, CDCl3, ppm) δ 0.85-0.90 (m, 3H), 1.25-1.55
(m, 9H), 1.67 (s, 3H), 1.95-2.02 (m, 1H), 2.19-2.26 (m, 1H),
2.57-2.72 (m, 2H), 7.61 (dd, J=8.4 Hz, 2.4 Hz, 1H), 8.05 (d, J=
2.4 Hz, 1H), 8.13 (d, J=8.7 Hz, 1H); 13C NMR (100 MHz, CDCl3,
ppm) δ 14.0, 22.5, 24.3, 26.8, 29.0, 30.3, 31.5, 39.2, 40.7, 93.6, 116.8,
121.7, 129.9, 130.8, 134.6, 135.4, 160.4, 173.0; ESI-MS m/z [M þ
H]þ 335.9; HRMS (ESI) calcd for C18H22ClNO3Na [M þ Na]þ
358.1186, found 358.1191. Diastereomer 2: white wax solid, mp
<50 °C. 1H NMR (300 MHz, CDCl3, ppm) δ 0.87-0.90 (m, 3H),
1.26-1.56 (m, 9H), 1.71 (s, 3H), 1.93-2.15 (m, 2H), 2.76-2.83 (m,
2H), 7.64 (dd, J=8.4 Hz, 2.4 Hz, 1H), 7.84 (d, J=8.4 Hz, 1H), 8.07
(d, J = 2.7 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm) δ 14.0,
22.5, 26.2, 27.1, 28.9, 31.5, 31.7, 38.1, 40.5, 94.7, 118.9, 123.9, 129.9,
131.8, 134.8, 135.2, 160.9, 175.3; ESI-MS m/z [M þ H]þ 335.9;
HRMS (ESI) calcd for C18H22ClNO3Na [M þ Na]þ 358.1186,
found 358.1190.
3a-Methyl-4-phenyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-
1,5-dione (4Da). Compound 4Da was obtained as a white solid
after purification by flash chromatography (PE/EA=1:1), mp
223-224 °C. 1H NMR (300 MHz, CDCl3, ppm) δ 1.77 (s, 3H),
1.80-1.86 (m, 1H), 2.28-2.39 (m, 1H), 2.59-2.65 (m, 2H),
7.25-7.33 (m, 3H), 7.39-7.51 (m, 3H), 7.61 (td, J=8.1 Hz, 1.5
Hz, 1H), 8.13 (dd, J=7.3 Hz, 1.2 Hz, 1H), 8.27 (d, J=8.4 Hz,
1H); 13C NMR (100 MHz, CDCl3, ppm) δ 25.4, 30.2, 31.7, 79.3,
120.0, 125.0, 128.5, 129.0, 129.4, 129.6, 133.6, 135.4, 137.0,
162.2, 171.5; ESI-MS m/z [MþNa]þ 314.9; HRMS (ESI) calcd
for C18H16N2O2Na [M þNa]þ 315.1109, found 315.1112.
4-Benzyl-7-methoxy-3a-methyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]-
quinazoline-1,5-dione (4Ea). Compound 4Ea was obtained as a
white solid after purification by flash chromatography (PE/
EA=1:1), mp 126-128 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.47 (s, 3H), 2.04-2.21 (m, 1H), 2.38-2.61 (m, 3H), 3.86 (s,
3H), 4.30 (d, J = 15.9 Hz, 1H), 5.24 (d, J = 15.9 Hz, 1H), 7.14
(dd, J=9 Hz, 3 Hz, 1 H), 7.25-7.35 (m, 5H), 7.65 (d, J=3 Hz,
1H), 8.17 (d, J=9 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm)
δ 23.3, 30.0, 31.1, 45.5, 55.6, 79.1, 111.4, 120.5, 120.8, 121.3,
126.8, 127.3, 128.7, 128.8, 137.8, 156.6, 162.4, 170.9; ESI-MS
m/z [M þ H]þ 337.0; HRMS (ESI) calcd for C20H20N2O3Na
[M þ Na]þ 359.1372, found 359.1394.
2-Hexyl-3a,7-dimethyl-3,3a-dihydro-1H-benzo[d]pyrrolo[2,1-b]-
[1,3]oxazine-1,5(2H)-dione (3Gc). Compound 3Gc was obtained
after purification by flash chromatography (PE/EA=4:1), and
the two diastereomers were separable by chromatography (dr=
1.2:1). Diastereomer 1: white wax solid, mp <50 °C. 1H NMR
(300 MHz, CDCl3, ppm) δ 0.86-0.91 (m, 3H), 1.29-1.56 (m,
9H), 1.66 (s, 3H), 1.95-2.02 (m, 1H), 2.19-2.26 (m, 1H), 2.40 (s,
3H), 2.55-2.69 (m, 2H), 7.49 (dd, J=8.4 Hz, 2.1 Hz, 1H), 7.90
(d, J = 0.9 Hz, 1H), 8.03 (d, J = 8.4 Hz, 1H); 13C NMR (100
MHz, CDCl3, ppm) δ 14.0, 20.9, 22.5, 24.3, 26.8, 29.0, 30.4, 31.6,
39.2, 40.7, 93.5, 115.4, 120.2, 130.3, 133.7, 135.3, 136.3, 161.8,
173.1; ESI-MS m/z [M þ H]þ 316.0; HRMS (ESI) calcd for
C19H25NO3Na [M þ Na]þ 338.1732, found 338.1732. Diaster-
1
eomer 2: white solid, mp 117-118 °C. H NMR (300 MHz,
7-Methoxy-3a,4-dimethyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]-
quinazoline-1,5-dione (4Fa). Compound 4Fa was obtained as
a white solid after purification by flash chromatography (PE/
EA=1:1), mp 116-118 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.41(s, 3H), 2.23-2.46 (m, 2H), 2.59-2.65 (m, 2H), 3.04 (s, 3H),
CDCl3, ppm) δ 0.87-0.91 (m, 3H), 1.25-1.55 (m, 9H), 1.69 (s,
3H), 1.94-2.12 (m, 2H), 2.40 (s, 3H), 2.75-2.81 (m, 2H), 7.49
(dd, J=8.4 Hz, 2.1 Hz, 1H), 7.72 (d, J=8.1 Hz, 1H), 7.90 (d, J=
1.2 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm) δ 14.0, 20.9,
3280 J. Org. Chem. Vol. 75, No. 10, 2010

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3.82 (s, 3H), 7.07 (dd, J=8.7 Hz, 3 Hz, 1H), 7.54 (d, J=3 Hz,
1H), 8.13 (d, J = 8.7 Hz, 1H); 13C NMR (100 MHz, CDCl3,
ppm) δ 21.4, 27.7, 30.0, 32.1, 55.5, 78.4, 111.2, 120.3, 120.4,
121.1, 128.5, 156.5, 161.7, 170.7; ESI-MS m/z [M þ H]þ 260.9;
HRMS (ESI) calcd for C14H16N2O3Na [M þ Na]þ 283.1059,
found 283.1048.
3a,4,7-Trimethyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-
1,5-dione (4Ga). Compound 4Ga was obtained as a white solid
after purification by flash chromatography (PE/EA=1:1), mp
130-132 °C. 1H NMR (300 MHz, CDCl3, ppm) δ 1.42 (s, 3H),
2.23-2.30 (m, 1H), 2.36 (s, 3H), 2.40-2.43 (m, 1H), 2.61-2.67
(m, 2H), 3.05 (s, 3H), 7.33 (dd, J=8.4 Hz, 2.1 Hz, 1H), 7.86 (d,
J=2.1 Hz, 1H), 8.12 (d, J=8.4 Hz, 1H);13C NMR (100 MHz,
CDCl3, ppm) δ 20.9, 21.5, 27.6, 30.1, 32.2, 78.3, 119.0, 119.4,
128.5, 132.6, 133.9, 134.6, 162.1, 170.9; ESI-MS m/z [M þ H]þ
245.0; HRMS (ESI) calcd for C14H16N2O2Na [MþNa]þ 267.1109,
found 267.1114.
7-Chloro-3a-methyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-
1,5-dione (4Ha). Compound 4Ha was obtained as a white solid
after purification by flash chromatography (PE/EA=1:1), mp
217-218 °C. 1H NMR (300 MHz, CDCl3, ppm) δ 1.55 (s, 3H),
2.38-2.43 (m, 2H), 2.67-2.73 (m, 2H), 7.53 (dd, J=8.7 Hz, 2.7
Hz, 1H), 8.01 (d, J=2.4 Hz, 1H), 8.13 (d, J=8.7 Hz, 1H), 8.96
(br, 1H); 13C NMR (100 MHz, CDCl3, ppm) δ 26.8, 29.9, 32.7,
74.4, 120.8, 122.1, 128.0, 130.5, 122.7, 134.2, 162.5, 171.7; ESI-
MS m/z [MþH]þ 250.9; HRMS (ESI) calcd for C12H11ClN2O2
[M - H]- 249.0431, found 249.0431.
4a-Methyl-3,4,4a,5-tetrahydro-1H-pyrido[1,2-a]quinazoline-
1,6(2H)-dione (4Ab). Compound 4Ab was obtained as a white
solid after purification by flash chromatography (PE/EA=1:1),
mp 201-203 °C. 1H NMR (300 MHz, CDCl3, ppm) δ 1.51 (s,
3H), 1.89-1.95 (m, 1H), 2.02-2.06 (m, 1H), 2.17-2.20 (m, 2H),
2.60-2.66 (m, 2H), 7.31 (t, J=7.5 Hz, 1H), 7.56 (t, J=7.5 Hz,
1H), 7.77 (d, J=7.5 Hz, 1H), 7.78 (br, 1H), 8.01 (d, J=7.5 Hz,
1H); 13C NMR (100 MHz, CDCl3, ppm) δ 17.0, 28.6, 33.5, 36.2,
71.4, 123.1, 125.7, 126.3, 127.3, 132.5, 138.1, 164.1, 169.0; ESI-
MS m/z [MþH]þ 231.0; HRMS (ESI) calcd for C13H14N2O2Na
[M þNa]þ 253.0953, found 253.0966.
127.8, 131.3, 132.5, 136.6, 163.3, 169.0; ESI-MS m/z [M þ H]þ
264.9; HRMS (ESI) calcd for C13H13ClN2O2Na [M þ Na]þ
287.0563, found 287.0562.
2-Hexyl-3a-methyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-
1,5-dione (4Ac). Compound 4Ac was obtained after purification
by flash chromatography (PE/EA=1:1), and the two diastereo-
mers were separable by chromatography (dr=1.3:1). Diastereo-
mer 1: white solid, mp 98-101 °C. 1H NMR (300 MHz, CDCl3,
ppm) δ 0.85-0.89 (m, 3H), 1.25-1.49 (m, 9H), 1.54 (s, 3H),
1.98-2.10 (m, 2H), 2.54-2.72 (m, 2H), 7.26 (t, J=7.8 Hz, 1H),
7.58 (td, J = 8.1 Hz, 1.8 Hz, 1H), 8.07 (dd, J =7.8 Hz, 0.9 Hz,
1H), 8.24 (d, J = 8.1 Hz, 1H), 8.78 (br, 1H); 13C NMR (100
MHz, CDCl3, ppm) δ 14.0, 22.5, 26.4, 26.9, 29.0, 30.3, 31.5, 39.9,
40.9, 72.5, 119.1, 120.1, 124.6, 128.2, 133.7, 135.8, 163.4, 173.5;
ESI-MS m/z [M þ H]þ 301.0; HRMS (ESI) calcd for C18H24-
N2O2Na [MþNa]þ 323.1735, found 323.1721. Diastereomer 2:
white solid, mp 122-123 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 0.88-0.92 (m, 3H), 1.31-1.57 (m, 9H), 1.60 (s, 3H), 1.97-2.08
(m, 2H), 2.60-2.67 (m, 1H), 2.73-2.79 (m, 1H), 7.32 (t, J=7.8
Hz, 1H), 7.61 (td, J=9 Hz, 1.5 Hz, 1H), 7.89 (d, J=8.1 Hz, 1H),
8.07 (d, J = 8.1 Hz, 1H), 8.76 (br, 1H); 13C NMR (100 MHz,
CDCl3, ppm) δ 14.0, 22.5, 27.3, 29.0, 29.4, 31.6, 32.0, 38.1, 41.2,
73.2, 120.9, 122.6, 125.4, 128.0, 133.5, 136.1, 164.3, 175.4; ESI-
MS m/z [MþH]þ 301.0; HRMS (ESI) calcd for C18H24N2O2Na
[M þ Na]þ 323.1735, found 323.1728.
2-Hexyl-3a,4-dimethyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quina-
zoline-1,5-dione (4Bc). Compound 4Bc was obtained after puri-
fication by flash chromatography (PE/EA = 1:1), and the two
diastereomers were separable by chromatography (dr =1.3:1).
Diastereomer 1: white wax solid, mp <50 °C.1H NMR (300 MHz,
CDCl3, ppm) δ 0.85-0.89 (m, 3H), 1.23-1.43 (m, 9H), 1.45 (s,
3H), 2.00-2.08 (m, 2H), 2.42-2.48 (m, 1H), 2.62-2.68 (m, 1H),
3.06 (s, 3H), 7.22 (t, 7.8 Hz, 1H), 7.51 (t, J=7.8 Hz, 1H), 8.06 (d,
J= 8.4 Hz, 1H), 8.27 (d, J= 8.7 Hz, 1H); 13C NMR (100 MHz,
CDCl3, ppm) δ 14.0, 21.5, 22.5, 26.9, 27.6, 29.1, 30.0, 31.6, 39.3,
40.9, 76.5, 119.1, 119.4, 124.6, 128.4, 133.2, 135.1, 161.9, 173.0;
ESI-MS m/z [MþH]þ 315.0; HRMS (ESI) calcd for C19H26N2O2-
Na [M þ Na]þ 337.1892, found 337.1907. Diastereomer 2: white
wax solid, mp <50 °C. 1H NMR (300 MHz, CDCl3, ppm) δ0.86-
0.90 (m, 3H), 1.24-1.53 (m, 9H), 1.49 (s, 3H), 1.96-2.00 (m, 2H),
2.66-.277 (m, 2H), 3.07 (s, 3H), 7.26 (t, J=7.8 Hz, 1H), 7.54 (t, J=
4a,5-Dimethyl-3,4,4a,5-tetrahydro-1H-pyrido[1,2-a]quinazoline-
1,6(2H)-dione (4Bb). Compound 4Bb was obtained as a white
solid after purification by flash chromatography (PE/EA=1:1),
mp 139-141 °C. 1H NMR (300 MHz, CDCl3, ppm) δ 1.39
(s, 3H), 1.86-1.96 (m, 2H), 2.09-2.18 (m, 1H), 2.35-2.73 (m,
3H), 3.12 (s, 3H), 7.30 (td, J=8.1 Hz, 1.5 Hz, 1H), 7.51 (td, J=
8.1 Hz, 1.5 Hz, 1H), 7.63 (dd, J=7.5 Hz, 1.2 Hz, 1H), 8.02 (dd,
J = 7.8 Hz, 1.5 Hz, 1H);13C NMR (100 MHz, CDCl3, ppm) δ
16.7, 24.3, 27.3, 33.5, 34.2, 75.3, 123.7, 125.8, 126.0, 127.6, 131.8,
137.1, 163.4, 169.2; ESI-MS m/z [M þH]þ 245.0; HRMS (ESI)
calcd for C14H16N2O2Na [MþNa]þ 267.1109, found 267.1121.
8-Methoxy-4a,5-dimethyl-3,4,4a,5-tetrahydro-1H-pyrido[1,2-a]-
quinazoline-1,6(2H)-dione (4Fb). Compound 4Fb was obtained
as a white solid after purification by flash chromatography (PE/
EA=1:1), mp 140-142 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.37 (s, 3H), 1.83-1.93 (m, 2H), 2.06-2.15 (m, 1H), 2.33-2.41
(m, 1H), 2.51-2.69 (m, 2H), 3.10 (s, 3H), 3.83 (s, 3H), 7.05 (m,
1H), 7.49 (d, J=3 Hz, 1H), 7.52 (d, J=8.7 Hz, 1H); 13C NMR
(100 MHz, CDCl3, ppm) δ 16.7, 24.2, 27.4, 33.4, 34.1, 55.6, 75.3,
110.1, 119.2, 124.6, 127.3, 130.3, 157.2, 163.2, 169.2; ESI-MS
m/z [M þ H]þ 275.0; HRMS (ESI) calcd for C15H18N2O3Na
[M þNa]þ 297.1215, found 297.1214.
7.8 Hz, 1H), 8.02 (d, J=7.8 Hz, 1H), 8.06 (d, J=7.8 Hz, 1H); 13
C
NMR (100 MHz, CDCl3, ppm) δ 14.0, 22.5, 25.3, 27.7, 28.1, 28.9,
31.5, 32.2, 36.3, 41.2, 77.5, 120.4, 121.1, 125.2, 128.3, 133.0, 135.1,
162.3, 174.5; ESI-MS m/z [MþH]þ 315.0; HRMS (ESI) calcd for
C19H26N2O2Na [M þNa]þ 337.1892, found 337.1902.
2-Hexyl-7-methoxy-3a,4-dimethyl-2,3,3a,4-tetrahydropyrrolo-
[1,2-a]quinazoline-1,5-dione (4Fc). Compound 4Fc was obtained
after purification by flash chromatography (PE/EA = 1:1),
and the two diastereomers were separable by chromatography
(dr=4:1). Diastereomer 1: white solid, mp 83-85 °C. 1H NMR
(300 MHz, CDCl3, ppm) δ 0.84-0.90 (m, 3H), 1.29-1.48 (m,
12H), 1.99-2.07 (m, 2H), 2.41-2.48 (m, 1H), 2.58-2.67 (m, 1H),
3.07 (s, 3H), 3.85 (s, 3H), 7.09 (dd, J=8.7 Hz, 3 Hz, 1H), 7.56 (d,
J = 3 Hz, 1H), 8.18 (d, J = 8.7 Hz, 1H); 13C NMR (100 MHz,
CDCl3, ppm) δ 14.0, 21.4, 22.5, 27.0, 27.7, 29.1, 30.1, 31.6, 39.3,
40.8, 55.6, 76.5, 111.2, 120.3, 120.4, 121.0, 128.7, 156.4, 172.6;
ESI-MS m/z [M þ H]þ 345.0; HRMS (ESI) calcd for C20H28-
N2O3Na [M þ Na]þ 367.1998, found 367.1986. Diastereomer 2:
white solid, mp 72-73 °C. 1H NMR (300 MHz, CDCl3, ppm) δ
0.87-0.92 (m, 3H), 1.25-1.53 (m, 12H), 1.95-2.00 (m, 2H),
2.66-2.77 (m, 2H), 3.07 (s, 3H), 3.85 (s, 3H), 7.11 (dd, J=9.3 Hz,
8-Chloro-4a-methyl-3,4,4a,5-tetrahydro-1H-pyrido[1,2-a]quina-
zoline-1,6(2H)-dione (4Hb). Compound 4Hb was obtained as
a white solid after purification by flash chromatography (PE/
EA=1:1), mp 187-189 °C. 1H NMR (300 MHz, CDCl3, ppm)
δ 1.52 (s, 3H), 1.89-2.07 (m, 2H), 2.15-2.25 (m, 2H), 2.60-2.66
(m, 2H), 7.51 (dd, J=8.7 Hz, 2.7 Hz, 1H), 7.75 (d, J=8.7 Hz,
1H), 7.99 (d, J = 2.7 Hz, 1H), 8.48 (br, 1H); 13C NMR (100
MHz, CDCl3, ppm) δ 16.9, 28.6, 33.5, 35.9, 71.5, 124.5, 127.0,
3 Hz, 1H), 7.57 (d, J=3 Hz, 1H), 7.92 (d, J =9.3 Hz, 1H); 13
C
NMR (100 MHz, CDCl3, ppm) δ 14.0, 22.6, 25.2, 27.7, 28.3, 29.0,
31.6, 32.3, 36.4, 41.1, 55.7, 77.6, 111.3, 120.2, 121.7, 122.8, 128.6,
157.0, 162.3, 174.4; ESI-MS m/z [M þ H]þ 345.0; HRMS
(ESI) calcd for C20H28N2O3Na [M þ Na]þ 367.1998, found
367.1989.
J. Org. Chem. Vol. 75, No. 10, 2010 3281

Feng et al.
JOCArticle
7-Chloro-2-hexyl-3a-methyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]-
quinazoline-1,5-dione (4Hc). Compound 4Hc was obtained after
purification by flash chromatography (PE/EA = 1:1), and the
two diastereomers were separable by chromatography (dr =
29.0, 29.4, 31.6, 32.0, 38.1, 41.2, 73.3, 122.2, 124.0, 127.9, 131.1,
133.5, 134.5, 163.2, 175.4; ESI-MS m/z [MþH]þ 334.9; HRMS
(ESI) calcd for C18H23ClN2O2Na [M þ Na]þ 357.1346, found
357.1352.
1
1.2:1). Diastereomer 1: white solid, mp 148-150 °C. H NMR
(300 MHz, CDCl3, ppm) δ 0.85-0.89 (m, 3H), 1.24-1.48 (m,
9H), 1.54 (s, 3H), 1.98-2.09 (m, 2H), 2.55-2.71 (m, 2H), 7.52
(dd, J=6.6 Hz, 2.1 Hz, 1H), 8.02 (d, J=1.8 Hz, 1H), 8.21 (d, J=
6.9 Hz, 1H), 8.82 (br, 1H); 13C NMR (100 MHz, CDCl3, ppm)
δ 14.0, 22.5, 26.5, 26.9, 29.1, 30.3, 31.6, 39.9, 41.0, 72.6, 120.5,
121.7, 128.0, 130.2, 133.7, 134.3, 162.4, 173.4; ESI-MS m/z [Mþ
H]þ 334.9; HRMS (ESI) calcd for C18H23ClN2O2Na [MþNa]þ
357.1346, found 357.1356. Diastereomer 2: white solid, mp
Acknowledgment. We gratefully acknowledge financial
support from the National Natural Science Foundation of
China (Grants 20721003 and 20872153), International Colla-
boration Projects (Grants 20720102040), the 863 Hi-Tech
Program of China (Grants 2006AA020602 and 2006AA-
10A201), and National S&T Major Projects (2009ZX09301-
001, 2009ZX09501-001 and 2009ZX09501-010).
1
141-142 °C. H NMR (300 MHz, CDCl3, ppm) δ 0.87-0.91
(m, 3H), 1.25-1.57 (m, 9H), 1.59 (s, 3H), 1.96-2.10 (m, 2H),
2.59-2.67 (m, 1H), 2.74-2.79 (m, 1H), 7.56 (dd, J=8.7 Hz, 2.4
Hz, 1H), 7.87 (d, J=8.4 Hz, 1H), 8.03 (d, J=2.4 Hz, 1H), 8.92
(br, 1H); 13C NMR (100 MHz, CDCl3, ppm) δ 14.0, 22.5, 27.3,
Supporting Information Available: Experimental details,
general information and 1H and 13C NMR spectra for all pro-
ducts, and crystallographic file in CIF format of 3Ha. This mate-
rial is available free of charge via the Internet at http://pubs.acs.org.
3282 J. Org. Chem. Vol. 75, No. 10, 2010