Photochemical reactions of N-(2-halogenoalkanoyl) derivatives of anilines

Article abstract of DOI:10.1002/1522-2675(20000705)83:7<1475::AID-HLCA1475>3.0.CO;2-Y

The photochemical reactions of 2-substituted N-(2-halogenoalkanoyl) derivatives 1 of anilines and 5 of cyclic amines are described. Under irradiation, 2-bromo-2-methylpropananilides 1a-e undergo exclusively dehydrobromination to give N-aryl-2-methylprop-2-enamides (= methacrylanilides) 3a-e (Scheme 1 and Table 1). On irradiation of N-alkyl- and N-phenyl-substituted 2-bromo-2-methylpropananilides 1f-m, cyclization products, i.e. 1,3-dihydro-2H-indol-2-ones (= oxindoles) 2f-m and 3,4- dihydroquinolin-2(1H)-ones (= dihydrocarbostyrils) 4f-m, are obtained, besides 3f-m. On the other hand, irradiation of N-methyl-substituted 2- chloro-2-phenylacetanilides 1o-q and 2-chloroacetanilide 1r gives oxindoles 2o-r as the sole product, but in low yields (Scheme 3 and Table 2). The photocyclization of the corresponding N-phenyl derivatives 1s-v to oxindoles 2s-v proceeds smoothly. A plausible mechanism for the formation of the photoproducts is proposed (Scheme 4). Irradiation of N-(2-halogenoalkanoyl) derivatives of cyclic amines 5a-c yields the cyclization products, i.e. five- membered lactams 6a, b, and/or dehydrohalogenation products 7a,c and their cyclization products 8a,c, depending on the ring size of the amines (Scheme 5 and Table 3).

Full text of DOI:10.1002/1522-2675(20000705)83:7<1475::AID-HLCA1475>3.0.CO;2-Y

Helvetica Chimica Acta ± Vol. 83 (2000)
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Photochemical Reactions of N-(2-Halogenoalkanoyl) Derivatives
of Anilines
by Takehiko Nishio*a), Hidenori Asaib), and Takenori Miyazakib)
a) Department of Chemistry and
b) Graduate School of Environmental Sciences, University of Tsukuba, Tsukuba-shi, Ibaraki, 305-8571 Japan
The photochemical reactions of 2-substituted N-(2-halogenoalkanoyl) derivatives 1 of anilines and 5 of
cyclic amines are described. Under irradiation, 2-bromo-2-methylpropananilides 1a ± e undergo exclusively
dehydrobromination to give N-aryl-2-methylprop-2-enamides (ˆ methacrylanilides) 3a ± e (Scheme 1 and
Table 1). On irradiation of N-alkyl- and N-phenyl-substituted 2-bromo-2-methylpropananilides 1f ± m,
cyclization products, i.e. 1,3-dihydro-2H-indol-2-ones (ˆoxindoles) 2f ± m and 3,4-dihydroquinolin-2(1H)-ones
(ˆdihydrocarbostyrils) 4f ± m, are obtained, besides 3f ± m. On the other hand, irradiation of N-methyl-
substituted 2-chloro-2-phenylacetanilides 1o ± q and 2-chloroacetanilide 1r gives oxindoles 2o ± r as the sole
product, but in low yields (Scheme 3 and Table 2). The photocyclization of the corresponding N-phenyl
derivatives 1s ± v to oxindoles 2s ± v proceeds smoothly. A plausible mechanism for the formation of the
photoproducts is proposed (Scheme 4). Irradiation of N-(2-halogenoalkanoyl) derivatives of cyclic amines 5a ± c
yields the cyclization products, i.e. five-membered lactams 6a,b, and/or dehydrohalogenation products 7a,c and
their cyclization products 8a,c, depending on the ring size of the amines (Scheme 5 and Table 3).
1. Introduction. ± Amide compounds in which the N-atom deactivates the carbonyl
group are photochemically much less reactive than carbonyl compounds [1], although
the photochemical cyclization of N-(halogenoacetyl) derivatives of aromatic amino
acid and pharmacodynamic amines with a C2- to C5-alkane moiety between the
aromatic group and the halogenoacetamide function for the syntheses of many
medium-sized lactams has been reported by several groups [2][3]. There is only one
report by Yonemitsu and co-workers on the photocyclization of 2-chloroacetanilides,
where two functional groups (chloroacetamide and aromatic ring) are directly
conjugated [3b]: the photocyclization yielding five-membered lactams, i.e. oxindoles,
involved N-alkyl-N-(chloroacetyl)anisidines having electron-donating substituents at
the benzene ring and N-(chloroacetyl)-N-methylaniline [3b]. However, the photo-
chemical reactions of 2-substituted N-(2-halogenoalkanoyl) derivatives of various
amines have received little attention. Herein we report the photochemical cyclization
and dehydrohalogenation of N-(2-halogenoalkanoyl) derivatives 1 and 5 of various
anilines and cyclic amines, respectively.
2. Results and Discussion. ± 2.1. Photochemical Reactions of N-(2-Halogenoalka-
noyl) Derivatives 1 of Anilines. Irradiation of N-(2-bromo-2-methylpropanoyl)
derivatives 1a ± e of anilines having electron-withdrawing and -donating substituents
Y such as chloro, ethoxycarbonyl, and methoxy at the benzene ring, in MeCN with a
high-pressure mercury lamp through a Pyrex filter under Ar at room temperature,
gave exclusively the N-aryl-2-methylprop-2-enamides (ˆ methacrylanilides) 3a ± e

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Helvetica Chimica Acta ± Vol. 83 (2000)
(Scheme 1 and Table 1). The latter were formed in moderate-to-good yields by
elimination of HBr at the side chain, and no evidence for any cyclized products was
found. The structures of the photoproducts 3a ± e were established by spectroscopic
1
data, particularly by H-NMR spectra (d 5.40 ± 5.47 and 5.76 ± 5.82 for CH2ˆ) and
microanalyses.
Scheme 1a)
a) For R and Y, see Table 1.
Table 1. Yield of Photoproducts 2 ± 4
Entry
1
Yield [%] a)
R
H
Y
H
2
3
4
1
2 b)
3 c)
4
5
6
1a
±
±
±
±
±
±
±
64
29
53
54
40
84
76
10
12
14
5
25
25
16
31
36
28
±
±
±
±
±
±
±
13
15
19
5
26
56
21
34
34
17
1b
1c
1d
1e
1f
H
H
H
H
4-Cl
4-CO2Et
4-MeO
2,4-(MeO)2
H
7
8
Me
21
29
33
13
19
9 d)
10 e)
11
12
13
14
15
16
17
1g
1h
1i
1j
1k
1l
Me
Me
Me
Me
Et
4-Me
4-Cl
4-CO2Et
4-MeO
H
f
)
12
17
18
34
PhCH2
Ph
H
H
1m
a) Yield of isolated product. b) In the presence of 2 mol-equiv. of 2,6-di(tert-butyl)phenol. c) In the presence of 2
mol-equiv. of triphenylmethane. d) In benzene. e) In MeOH. f) Traces.
Irradiation of N-alkyl- and N-phenyl-substituted N-(2-bromo-2-methylpropanoyl)
derivatives of anilines 1f ± m under the same conditions as described for 1a ± e yielded
as cyclization products the 1,3-dihydro-2H-indol-2-ones (ˆoxindoles) 2f ± m and the
3,4-dihydroquinolin-2(1H)-ones (ˆdihydrocarbostyrils) 4f ± m, and as dehydrobromi-
nation products the methacrylanilides 3f ± m (Scheme 1 and Table 1). Similar results
were obtained when 1f was irradiated in benzene or MeOH (Entries 9 and 10 in
1
Table 1). H-NMR Monitoring of the irradiation of 1m showed that the yield of
dihydrocarbostyril 4m increased, while that of methacrylanilide 3m decreased, with
irradiation time. Upon irradiation of the isolated methacrylanilides 3f ± g and 3k ± m
under similar conditions, the dihydrocarbostyrils 4f ± g and 4k ± m were obtained. The

Helvetica Chimica Acta ± Vol. 83 (2000)
1477
formation of 4 can be explained in terms of an electrocyclic ring closure of the 6 p-
electron conjugated enamides 3 [4] (see below).
Owing to mesomerism, which confers to the amide group a partial double-bond
character, N-(2-halogenoacyl)anilides 1a ± e (R ˆ H) exist almost exclusively in the
trans form with respect to the aromatic moiety and the halogenoalkyl group (see
Scheme 2). On the other hand, in unsymmetrically N,N-disubstituted (2-halogeno-
acyl)anilides 1f ± m (R ˆ alkyl, Ph), the prefered isomer has the halogenoalkyl group
cis to the aromatic moiety [3b]. Therefore, on irradiation, 1a ± e (R ˆ H) could not
cyclize to oxindoles 2a ± e but underwent dehydrobromination to the methacrylanilides
3a ± e, while 1f ± m cyclized to oxindoles 2f ± m.
Scheme 2
Irradiation in MeCN of N-methyl-substituted 2-chloro-2-phenylacetanilide 1q,
which has no alkyl substituent at C(2), gave a cyclization product, the oxindole 2q, as
the sole product, though in only 9% yield (Scheme 3 and Table 2). Similarly, the 2-
chloro-2-phenylacetanilides 1n ± p having electron-donating or electron-withdrawing
groups were cyclized in poor yields to oxindoles 2n ± p. Irradiation of the N-methyl-
substituted 2-chloroacetyl derivative 1r of p-anisidine (ˆ4-methoxybenzenamine) in
MeCN or in MeCN/H2O gave the oxindole 2r in low yield (Entries 5 ± 7 in Table 2)
[3b]. On the other hand, photocyclization under similar conditions of N-phenyl-
substituted 2-halogenoacetanilides 1s ± v possessing the bulky Ph substituent at the N-
atom proceeded smoothly to yield oxindoles 2s ± v in 26 ± 60% yields.
Scheme 3a)
a) For R, R1, X, and Y, see Table 2.
Irradiation of 1a in the presence of a radical quencher such as 2,6-di(tert
butyl)phenol or triphenylmethane resulted in a decrease of the dehydrohalogenation
to methacrylanilide 3a (Entries 2 and 3 in Table 1). The yield of the cyclization product
2v was slightly increased by the addition of magnesium perchlorate to the photo-
reaction of 1v (Entry13 in Table 2) [5a]. The addition of silver trifluoromethanesulfate
on irradiation of 1u also affected the yield of the cyclization product 2u (Entry11 in
Table 2) [5b].

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Helvetica Chimica Acta ± Vol. 83 (2000)
Table 2. Yield of Oxindoles 2n ± v
Entry
1
Yield [%] a)
R
R1
X
Y
1
2
3
4
5
6 b)
7 c)
8
1n
1o
1p
1q
1r
H
Ph
Ph
Ph
Ph
H
Cl
Cl
Cl
Cl
Cl
2,4-(MeO)2
4-MeO
4-Cl
H
4-MeO
19
15
6
9
6
Me
Me
Me
Me
10
7
1s
1t
1u
Ph
Ph
Ph
H
H
Ph
Cl
Br
Cl
H
H
H
39
26
60
70
26
30
9
10
11 d)
12
13 e)
1v
Ph
Me
Cl
H
a) Yield of isolated product. b) In MeCN/H2O 6 : 1. c) In MeCN/H2O 3 : 4. d) In the presence of 1 mol-equiv. of
CF3SO3Ag. e) In the presence of 1 mol-equiv. of Mg(ClO4)2.
From these results, a plausible mechanism for the formation of photoproducts 2 ± 4
can be deduced (Scheme 4). Excitation of the N-(2-halogenoalkanoyl) derivative 1 of
aniline leads to the formation of the exciplex or the biradical ion intermediate A by an
intramolecular electron transfer between the aromatic chromophore and the halogen-
oalkanoyl moiety, which readily cyclizes to the oxindole 2 with loss of a proton when R
is an alkyl or phenyl substituent (Path a). The methacrylanilide 3 might be formed by a
C-halogen bond homolysis (! B), followed by dehydrohalogenation (Path b), and the
formation of dihydrocarbostyril 4 can be best explained in terms of the conjugated 6-p-
electron photocyclization of the enamide 3 [4b ± c]. A possible alternative intermedi-
ate, the a-lactam C, is precluded since when 1r was irradiated in MeCN/H2O, no
hydrolysis products of C could be detected [3b].
2.2. Photochemical Reactions of N-(2-Halogenoalkanoyl) Derivatives 5 of Cyclic
Amines. Irradiation of N-(2-bromo-2-methylpropanoyl)tetrahydroquinoline 5a in
MeCN under the same conditions as described for 1a ± e gave the cyclization product
6a, N-methacroyltetrahydroquinoline 7a, and tricyclic lactam 8a in 51, 13, and 8% yield,
respectively, whereas the N-(2-chloro-2-phenylacetyl)tetrahydroquinoline 5b furnished
cyclization product 6b in 37% yield (Scheme 5 and Table 3). Under similar conditions,
N-(2-bromo-2-methylpropanoyl)indoline 5c did not cyclize, probably due to ring strain;
only the dehydrohalogenation product 7c (27%) and the tricyclic lactam 8c (36%) were
isolated. Longer irradiation of 5c led to an increased yield (51%) of 8c. The formation
of the tricyclic lactams 8 can be understood in terms of a photochemical electrocyclic
ring closure of enamides 7 [4], the latter being produced by photochemical elimination
of hydrogen halide at the side chain of 5.

Helvetica Chimica Acta ± Vol. 83 (2000)
1479
Scheme 4
Scheme 5a)
a) For R1, R2, and X, see Table 3.

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Helvetica Chimica Acta ± Vol. 83 (2000)
Table 3. Yield of Photoproducts 6 ± 8
5
Yield [%] a)
n
R1
R2
X
6
7
8
5a
2
2
1
1
Me
Ph
Me
Me
Me
H
Me
Me
Br
Cl
Br
Br
51
37
±
13
±
27
13
8
5b
±
5c b)
5c c)
36
51
±
a) Yield of isolated product. b) Irradiation time 5 h. c) Irradiation time 10 h.
Experimental Part
General. Chromatography: silica gel Wakogel C-300 and Merck 60 for flash chromatography (FC). M.p.
and b.p.: Yanaco micro melting-point apparatus (MP-J3) and Shibata glass tube oven distillation apparatus
(GTO-350RD), resp.; uncorrected. IR Spectra: Jasco-FT/IR-300 spectrophotometer; in cmÀ1. 1H- and 13C-NMR
Spectra: Jeol-JNM-EX-270 (270 MHz) or Varian-Gemini-200 (200 MHz); in CDCl3 with Me4Si as an internal
standard; d in ppm, J in Hz.
Irradiation of N-(2-Halogenoalkanoyl) Derivatives 1 and 5: General Procedure. A soln. of 1 or 5 (1 ±
2 mmol) in MeCN (70 ml), unless otherwise noted, was irradiated in a Pyrex tube with a high-pressure Hg lamp
(Halos EHP 500 W, Eikosha) under Ar for 4 ± 15 h at r.t. After evaporation, the residue was chromatographed
(silica gel, toluene/AcOEt 50 :1 ! 4 :1) to yield products 2 ± 4 and 6 ± 8. The structures of 2f,k ± m,q,s ± v were
confirmed by direct comparison of their spectral data with those of previously described samples [5].
Irradiation of the methacrylanilide derivatives 3f ± g,k ± m (1 mmol) in benzene or MeCN (70 ml) under
the same conditions gave the dihydrocarbostyrils 4f ± g,k ± m in 20 ± 50% yield.
2-Methyl-N-phenylprop-2-enamide (ˆ Methacrylanilide; 3a). M.p. 84.5 ± 86.58 ([4a]): 868). IR (KBr): 3292,
1
1656, 1619, 1595, 1491, 1439, 759, 696. H-NMR: 2.04 (d, J ˆ 0.7, 3 H); 5.44 (br. s, 1 H); 5.78 (d, J ˆ 0.7, 1 H);
7.08 ± 7.14 (m, 1 H); 7.25 ± 7.36 (m, 1 H); 7.54 ± 7.60 (m, 2 H); 7.65 (br. s, 1 H). 13C-NMR: 18.8; 119.8; 120.1; 124.4;
129.0; 137.8; 140.9; 166.7.
N-(4-Chlorophenyl)-2-methylprop-2-enamide (3b). B.p. 1808/3 Torr. IR (film): 3440, 1682, 1630, 1592, 1511,
1493, 790, 735. 1H-NMR: 2.04 (br. s, 3 H); 5.46 (br. s, 1 H); 5.78 (s, 1 H); 7.28 (d, J ˆ 8.6, 2 H); 7.51 (d, J ˆ 8.6,
2 H); 7.63 (br. s, 1 H). 13C-NMR: 18.7; 120.2; 121.3; 129.0; 136.4; 140.6; 166.6. Anal. calc. for C10H10ClNO
(195.65): C 61.38, H 5.12, N 7.16; found: C 61.42, H 5.03, N 6.89.
4-[(2-Methyl-1-oxoprop-2-enyl)amino]benzoic Acid Ethyl Ester (3c). M.p. 98 ± 998. IR (KBr): 3386, 1685,
1615, 1596, 1525, 1281, 852, 770. 1H-NMR: 1.37 (t, J ˆ 7.3, 3 H); 2.04 (s, 3 H); 4.34 (q, J ˆ 7.3, 2 H); 5.47 (d, J ˆ
1.3, 1 H); 5.82 (s, 1 H); 7.69 (d, J ˆ 8.6, 2 H); 7.96 ± 8.01 (m, 2 H); 8.19 (br. s, 1 H). 13C-NMR: 14.2; 18.6; 60.8;
119.1; 120.4; 125.8; 130.5; 140.5; 142.0; 166.1; 166.9. Anal. calc. for C13H15NO3 (233.26): C 66.93, H 6.48, N 6.01;
found: C 66.91, H 6.53, N 5.81.
N-(4-Methoxyphenyl)-2-methylprop-2-enamide (3d). M.p. 86 ± 878. IR (KBr): 3313, 1654, 1625, 1514, 1251,
826. 1H-NMR: 2.02 (s, 3 H); 3.77 (s, 3 H); 5.40 (s, 1 H); 5.76 (s, 1 H); 6.83 (d, J ˆ 8.9, 2 H); 7.45 (d, J ˆ 8.9, 2 H);
7.72 (br. s, 1 H). 13C-NMR: 18.7; 55.3; 114.0; 119.6; 122.0; 130.9; 140.7; 156.4; 166.6. Anal. calc. for C11H13NO2
(191.22): C 69.09, H 6.85, N 7.33; found: C 68.89, H 6.91, N 7.21.
N-(2,4-Dimethoxyphenyl)-2-methylprop-2-enamide (3e). M.p. 49.5 ± 518. IR (KBr): 3338, 1657, 1617, 1534,
1500, 1214, 830. 1H-NMR: 2.06 (d, J ˆ 1.0, 3 H); 3.79 (s, 3 H); 3.86 (s, 3 H); 5.42 (br. s, 1 H); 5.81 (d, J ˆ 1.0, 1 H);
6.47 ± 6.50 (m, 2 H); 8.02 (br. s, 1 H); 8.30 (dd, J ˆ 1.0, 9.2, 1 H). 13C-NMR: 18.6; 55.5; 55.7; 98.5; 103.7; 119.6;
120.5; 121.2; 140.8; 149.3; 156.3; 165.8. Anal. calc. for C12H15NO3 (221.25): C 65.14, H 6.84, N 6.33; found:
C 65.13, H 6.83, N 6.11.
N,2-Dimethyl-N-phenylprop-2-enamide (3f). M.p. 54 ± 558. IR (KBr): 1655, 1627, 1594, 1496, 1242, 783, 708.
1H-NMR: 1.76 (br. s, 3 H); 3.35 (s, 3 H); 5.00 (d, J ˆ 1.0, 1 H); 5.03 (br. s, J ˆ 1.0); 7.12 ± 7.16 (m, 2 H); 7.24 ± 7.40
(m, 3 H). 13C-NMR: 20.1; 37.5; 119.4; 126.5; 126.9; 129.2; 140.7; 144.6; 172.0. Anal. calc. for C11H13NO (175.22):
C 75.40, H 7.48, N 7.99; found: C 75.18, H 7.58, N 8.08.
3,4-Dihydro-1,3-dimethylquinolin-2(1H)-one (4f). B.p. 1758/3 Torr. IR (film): 1673, 1603, 1498, 1472, 1375,
1267, 755, 735, 688. 1H-NMR: 1.25 (d, J ˆ 6.6, 3 H); 2.60 ± 2.73 (m, 2 H); 2.88 ± 2.96 (m, 1 H); 3.35 (s, 3 H);

Helvetica Chimica Acta ± Vol. 83 (2000)
1481
6.94 ± 7.03 (m, 2 H); 7.21 ± 7.28 (m, 1 H); 7.13 ± 7.17 (m, 1 H). 13C-NMR: 15.7; 29.8; 33.3; 35.3; 114.4; 122.6; 125.7;
127.3; 127.8; 140.4; 173.2. Anal. calc. for C11H13NO (175.22): C 75.40, H 7.48, N 7.99; found: C 75.11, H 7.24,
N 8.05.
1,3-Dihydro-1,3,3,5-tetramethyl-2H-indol-2-one (2g). M.p. 57 ± 588. IR (KBr): 1709, 1618, 1507, 1381, 1349,
1
800. H-NMR: 1.35 (s, 6 H); 2.34 (s, 3 H); 3.19 (s, 3 H); 6.73 (d, J ˆ 7.5, 1 H); 7.04 (d, J ˆ 7.5, 2 H). 13C-NMR:
21.1; 24.4; 26.2; 44.2; 107.7; 123.1; 127.8; 131.9; 135.9; 140.2; 181.3. Anal. calc. for C12H15NO (189.25): C 76.15,
H 7.99, N 7.40; found: C 75.89, H 8.08, N 7.21.
N,2-Dimethyl-N-(4-methylphenyl)prop-2-enamide (3g). B.p. 1958/2 Torr. IR (film): 1713, 1651, 1615, 1505,
1366, 1279, 809. 1H-NMR: 1.76 (s, 3 H); 2.35 (s, 3 H); 3.32 (s, 3 H); 4.99 (br. s, 1 H); 5.02 (br. s, 1 H); 7.02 (d, J ˆ
7.9, 1 H); 7.14 (d, J ˆ 7.9, 2 H). 13C-NMR: 20.3; 20.9; 37.6; 119.1; 126.2; 129.7; 136.7; 140.7; 141.9; 172.0. Anal.
calc. for C12H15NO (189.25): C 76.15, H 7.99, N 7.40; found: C 76.48, H 7.99, N 7.41.
3,4-Dihydro-1,3,6-trimethylquinolin-2(1H)-one (4g). M.p. 38 ± 398. IR (KBr) 1673, 1615, 1508, 1473, 1366,
1278, 812. 1H-NMR: 1.24 (d, J ˆ 6.6, 3 H); 2.30 (s, 3 H); 2.59 ± 2.70 (m, 2 H); 2.83 ± 2.91 (m, 1 H); 3.33 (s, 3 H);
6.85 (d, J ˆ 8.3, 1 H); 6.97 ± 7.15 (m, 3 H). 13C-NMR: 15.7; 20.6; 29.8; 33.3; 35.6; 114.4; 127.7; 128.6; 129.5; 132.2;
136.9; 173.1. Anal. calc. for C12H15NO (189.25): C 76.15, H 7.99, N 7.40; found: C 76.39, H 8.01, N 7.27.
5-Chloro-1,3-dihydro-1,3,3-trimethyl-2H-indol-2-one (2h). M.p. 88 ± 898. IR (KBr): 1708, 1610, 1491, 1344,
813. 1H-NMR: 1.37 (s, 6 H); 3.21 (s, 3 H); 6.76 (d, J ˆ 8.2, 1 H); 7.17 ± 7.27 (m, 2 H). 13C-NMR: 24.3; 26.3; 44.5;
108.9; 122.9; 127.6; 127.9; 137.5; 141.2; 180.8. Anal. calc. for C11H12ClNO (209.67): C 63.01, H 5.77, N 6.68; found:
C 62.95, H 5.84, N 6.59.
N-(4-Chlorophenyl)-N,2-dimethylprop-2-enamide (3h). M.p. ca. 378. IR (KBr): 1739, 1651, 1590, 1494,
1455, 1380, 1229, 839. 1H-NMR: 1.78 (d, J ˆ 1.0, 3 H); 3.34 (s, 3 H); 4.99 (br. s, 1 H); 5.08 (br. s, 1 H); 7.09 (d, J ˆ
8.6, 2 H); 7.33 (d, J ˆ 8.6, 2 H). 13C-NMR: 20.2; 37.6; 119.7; 127.7; 129.3; 132.5; 140.3; 143.1; 171.8. Anal. calc. for
C11H12ClNO (209.67): C 63.01, H 5.77, N 6.68; found: C 63.38, H 5.90, N 6.39.
6-Chloro-3,4-dihydro-1,3-dimethylquinolin-2(1H)-one (4h). M.p. 53 ± 548. IR (KBr): 1682, 1598, 1495, 1471,
1
1422, 1361, 1268, 812. H-NMR: 1.25 (d, J ˆ 6.6, 3 H); 2.57 ± 2.72 (m, 2 H); 2.85 ± 2.93 (m, 1 H); 3.33 (s, 3 H);
6.88 (d, J ˆ 8.6, 1 H); 7.13 ± 7.28 (m, 2 H). Anal. calc. for C11H12ClNO (209.67): C 63.01, H 5.77, N 6.68; found:
C 63.04, H 5.94, N 6.58.
4-[Methyl(2-methyl-1-oxoprop-2-enyl)amino]benzoic Acid Ethyl Ester (3i). B.p. 1758/3 Torr. IR (film):
1714, 1568, 1631, 1603, 1509, 1366, 1276, 1105, 775, 707. 1H-NMR: 1.40 (t, J ˆ 6.3, 3 H); 1.81 (d, J ˆ 1.7, 3 H); 3.38
(s, 3 H); 4.34 ± 4.44 (m, 2 H); 4.99 (br. s, 1 H); 5.00 (br. s, 1 H); 7.21 (d, J ˆ 8.6, 2 H); 8.03 (d, J ˆ 8.6, 2 H).
13C-NMR: 14.1; 20.0; 37.2; 61.0; 119.9; 125.7; 128.4; 130.5; 140.2; 148.5; 165.6; 171.6. Anal. calc. for C14H17NO3
(247.28): C 67.99, H 6.93, N 5.66; found: C 67.72, H 6.93, N 5.63.
1,2,3,4-Tetrahydro-1,3-dimethyl-2-oxoquinoline-6-carboxylic Acid Ethyl Ester (4i). M.p. 78 ± 798. IR (KBr):
1
1710, 1639, 1607, 1497, 1366, 1284, 1187, 1120, 1027, 769. H-NMR: 1.27 (d, J ˆ 6.6, 3 H); 1.40 (t, J ˆ 7.3, 3 H);
2.60 ± 2.76 (m, 2 H); 2.96 ± 3.04 (m, 1 H); 3.39 (s, 3 H); 4.37 (q, J ˆ 7.3, 2 H); 6.99 (d, J ˆ 8.6, 1 H); 7.85 (br. s,
1 H); 7.95 (dd, J ˆ 2.0, 8.6, 1 H). 13C-NMR: 14.3; 15.6; 29.9; 33.0; 35.3; 60.8; 114.0; 124.6; 125.3; 129.1; 129.3;
144.2; 166.1; 173.2. Anal. calc. for C14H17NO3 (247.28); C 67.99, H 6.93, N 5.66; found: C 67.89, H 6.90, N 5.65.
1,3-Dihydro-5-methoxy-1,3,3-trimethyl-2H-indol-2-one (2j). Oil. IR (film): 1713, 1602, 1503, 1470, 1434,
1
1289, 1218, 1066, 805, 695. H-NMR: 1.37 (s, 6 H); 3.20 (s, 3 H); 3.80 (s, 3 H); 6.73 ± 6.84 (m, 3 H). 13C-NMR:
24.3; 26.2; 44.6; 55.7; 108.2; 110.0; 111.5; 115.8; 137.2; 156.0; 181.0. Anal. calc. for C12H15NO2 (205.25): C 70.22,
H 7.37, N 6.82; found: C 70.14, H 7.54, N 6.58.
N-(4-Methoxyphenyl)-N,2-dimethylprop-2-enamide (3j). B.p. 1908/3 Torr. IR (film): 1651, 1632, 1513, 1454,
1366, 1290, 1248, 838. 1H-NMR: 1.74 (s, 3 H); 3.30 (s, 3 H); 3.80 (s, 3 H); 4.99 (br. s, 1 H); 5.03 (be. s, 1 H); 6.85
(d, J ˆ 6.9, 2 H); 7.05 (d, J ˆ 6.9, 2 H). 13C-NMR: 20.4; 37.8; 55.4; 114.4; 118.9; 127.8; 137.4; 140.9; 158.3; 172.1.
Anal. calc. for C12H15NO2 (205.25): C 70.22, H 7.37, N 6.82; found: C 70.57, H 7.54, N 6.73.
3,4-Dihydro-6-methoxy-1,3-dimethylquinolin-2(1H)-one (4j). Oil. IR (film): 1667, 1591, 1506, 1473, 1433,
1
1374, 1297, 1244, 1034, 807. H-NMR: 1.24 (d, J ˆ 6.3, 3 H); 2.58 ± 2.71 (m, 2 H); 2.82 ± 2.91 (m, 1 H); 3.33 (s,
3 H); 3.71 (s, 3 H); 6.72 ± 6.90 (m, 3 H). Anal. calc. for C12H15NO2 (205.25): C 70.22, H 7.37, N 6.82; found:
C 70.47, H 7.54, N 6.73.
N-Ethyl-2-methyl-N-phenylprop-2-enamide (3k). B.p. 1758/3 Torr. IR (film): 1650, 1625, 1595, 1495, 1455,
1
1394, 1227, 766, 699. H-NMR: 1.15 (t, J ˆ 7.2, 3 H); 1.75 (br. s, 3 H); 3.38 (q, J ˆ 7.3, 2 H); 4.89 ± 5.0 (m, 2 H);
7.02 ± 7.13 (m, 2 H); 7.19 ± 7.39 (m, 3 H). 13C-NMR: 12.9; 20,4; 44.6; 119.0; 127.1; 127.6; 129.2; 141.1; 142.9; 171.6.
Anal. calc. for C12H15NO (189.25): C 76.15, H 7.99, N 7.40; found: C 76.39, H 7.94, N 7.43.
1-Ethyl-3,4-dihydro-3-methylquinolin-2(1H)-one (4k). B.p. 1908/2 Torr. IR (film): 1665, 1601, 1493, 1460,
1
1384, 1243, 819, 756. H-NMR: 1.25 (t, J ˆ 6.9, 3 H); 1.25 (d, J ˆ 6.6, 3 H); 2.57 ± 2.68 (m, 2 H); 2.87 ± 2.94 (m,

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Helvetica Chimica Acta ± Vol. 83 (2000)
1 H); 3.88 ± 4.06 (m, 2 H); 6.95 ± 7.02 (m, 2 H); 7.14 ± 7.27 (m, 2 H). Anal. calc. for C12H15NO (189.25): C 76.15,
H 7.99, N 7.40; found: C 76.15, H 7.84, N 7.37.
N-Benzyl-2-methyl-N-phenylprop-2-enamide (3l). M.p. 49 ± 508. IR (KBr): 1647, 1619, 1595, 1491, 1455,
1389, 756, 697. 1H-NMR: 1.78 (s, 3 H); 4.97 (s, 2 H); 5.00 ± 5.05 (m, 2 H); 6.97 (dd, J ˆ 1.3, 7.6, 2 H); 7.19 ± 7.30
(m, 7 H). 13C-NMR: 20.4; 53.2; 119.4; 127.3; 127.4; 128.4; 129.0; 137.8; 140.7; 143.2; 171.8. Anal. calc. for
C17H17NO (251.31): C 81.24, H 6.84, N 5.57; found: C 81.13, H 6.84, N 5.53.
1-Benzyl-3,4-dihydro-3-methylquinolin-2(1H)-one (4l). B.p. 2058/2 Torr. IR (film): 1679, 1599, 1495, 1454,
1
1389, 1263, 1225, 756, 695. H-NMR: 1.33 (d, J ˆ 6.6, 3 H); 2.72 ± 2.82 (m, 2 H); 2.94 ± 3.01 (m, 1 H); 5.15 (AB
(ꢀqꢁ), J ˆ 6.2, 14.4, 2 H); 6.85 (d, J ˆ 8.3, 1 H); 6.92 ± 6.98 (m, 1 H); 7.01 ± 7.36 (m, 8 H). 13C-NMR: 15.7, 33.4;
35.6; 46.5; 115.4; 122.8; 125.7; 126.3; 127.0; 127.4; 128.0; 128.7; 137.2; 139.7; 173.3. Anal. calc. for C17H17NO
(251.31): C 81.24, H 6.84, N 5.57; found: C 81.59, H 6.63, N 5.60.
2-Methyl-N,N-diphenylprop-2-enamide (3m). The products 3m and 4m could not be completely separated
by FC. Amide 3m was prepared independently by the reaction of diphenylamine and methacryloyl chloride in
the presence of Et3N. M.p. 101 ± 1028. IR (KBr): 1658, 1625, 1590, 1490, 1340, 1229, 759, 693. 1H-NMR: 1.84 (br.
s, 3 H); 5.17 (br. s, 1 H); 5.23 (d, J ˆ 1.0, 1 H); 7.13 ± 7.36 (m, 10 H). 13C-NMR: 19.8; 120.9; 126.5; 127.1; 127.4;
129.0; 129.5; 141.1; 143.4; 171.9. Anal. calc. for C16H15NO (237.29): C 80.98, H 6.37, N 5.90; found: C 81.09,
H 6.23, N 5.84.
3,4-Dihydro-3-methyl-1-phenylquinolin-2(1H)-one (4m). M.p. (3m/4m 1:1) 77 ± 808. IR (KBr): 1686, 1662,
1620, 1590, 1491, 1458, 1328, 1268, 758, 696. 1H-NMR: 1.33 (d, J ˆ 6.6, 3 H); 2.76 ± 2.91 (m, 2 H); 2.97 ± 3.09 (m,
1 H); 6.33 (dd, J ˆ 1.0, 7.6, 1 H); 6.92 ± 7.05 (m, 2 H); 7.13 ± 7.51 (m, 6 H). 13C-NMR: 15.5; 33.5; 35.9; 172.9;
signals for arom. and olef. C-atoms. Anal. (3m/4m) calc. for C16H15NO (237.29): C 80.78, H 6.35, N 5.92; found:
C 81.09, H 6.23, N 5.84.
1,3-Dihydro-5,7-dimethoxy-3-phenyl-2H-indol-2-one (2n). B.p. 1758/3 Torr. IR (film): 3640, 1700, 1507.
1H-NMR: 3.75 (s, 3 H); 3.77 (s, 3 H); 5.11 (s, 1 H); 6.35 ± 6.53 (m, 2 H); 7.24 ± 7.59 (m, 5 H); 8.61 (br. s, 1 H).
13C-NMR: 55.4; 55.7; 74.6; 98.6; 103.6; 120.4; 126.7; 128.5; 128.7; 139.4; 149.6; 156.6; 168.7.
1,3-Dihydro-5-methoxy-1-methyl-3-phenyl-2H-indol-2-one (2o). M.p. 118 ± 1198. IR (KBr): 1730, 1601,
1
1495, 1455, 696. H-NMR: 3.22 (s, 3 H); 3.75 (s, 3 H); 4.64 (s, 1 H); 6.77 ± 6.88 (m, 3 H); 7.13 ± 7.53 (m, 5 H).
13C-NMR: 26.7; 52.6; 58.9; 172.5; signals for arom. C-atoms. Anal. calc. for C16H15NO2 (253.29): C 75.88, H 5.97,
N 5.53; found: C 75.50, H 5.89, N 5.40.
5-Chloro-1,3-dihydro-1-methyl-3-phenyl-2H-indol-2-one (2p). M.p. 131 ± 1328. IR (KBr): 1701, 1601, 1490,
1350, 1341, 1099, 815, 728, 699. 1H-NMR: 3.23 (s, 3 H); 4.59 (s, 1 H); 6.81 (d, J ˆ 8.6, 1 H); 7.13 ± 7.21 (m, 3 H);
7.25 ± 7.38 (m, 4 H). 13C-NMR: 26.7; 52.0; 109.0; 125.4; 127.8; 128.0; 128.3; 128.6; 129.0; 130.4; 135.8; 143.0;
175.4. Anal. calc. for C15H13ClNO (258.73): C 69.90, H 4.46, N 5.44; found: C 69.61, H 4.72, N 5.44.
1,3-Dihydro-5-methoxy-1-methyl-2H-indol-2-one (2r). M.p. 458. IR (KBr): 1701, 1560, 1457, 752, 705.
1H-NMR: 3.17 (s, 3 H); 3.49 (s, 2 H); 3.78 (s, 3 H); 6.69 ± 7.11 (m, 3 H). 13C-NMR: 26.1; 36.0; 55.4; 108.1; 111.8;
112.0; 122.8; 138.1; 138.7; 155.7; 174.6.
5,6-Dihydro-1,1-dimethyl-4H-pyrrolo[3,2,1-ij]quinolin-2(1H)-one (6a). B.p. 1858/2 Torr. IR (film): 1712,
1
1627, 1603, 1485, 1387, 1352, 1240, 1169, 752. H-NMR: 1.37 (s, 6 H); 2.03 (quint., J ˆ 5.9, 2 H); 2.78 (t, J ˆ 5.9,
2 H); 3.71 (t, J ˆ 5.9, 2 H); 6.90 ± 7.05 (m, 3 H). 13C-NMR: 21.1; 24.0; 24.5; 38.7; 45.4; 119.9; 120.0; 121.8; 126.3;
134.2; 138.2; 180.2. Anal. calc. for C13H15NO (201.26): C 77.58, H 7.51, N 6.96; found: C 77.27, H 7.50, N 6.67.
1,2,3,4-Tetrahydro-1-(2-methyl-1-oxoprop-2-enyl)quinoline (7a). B.p. 1678/2 Torr. IR (film): 1650, 1493,
1452, 1381, 1294, 1224, 765. 1H-NMR: 1.87 (br. s, 3 H); 1.98 (quint., J ˆ 6.6, 2 H); 2.76 (t, J ˆ 6.6, 2 H); 3.80 (t,
J ˆ 6.6, 2 H); 5.14 (br. s, 1 H); 5.18 (br. s, 1 H); 7.02 ± 7.28 (m, 4 H). 13C-NMR: 19.8; 23.9; 26.7; 43.9; 119.0; 124.1;
124.7; 125.8; 128.3; 131.3; 138.9; 141.2; 171.4. Anal. calc. for C13H15NO (201.26): C 77.58, H 7.51, N 6.96; found:
C 77.45, H 7.48, N 6.75.
1,2-Dihydro-2-methyl-3H,5H-pyrido[3,2,1-ij]quinolin-3-one (8a). M.p. 49 ± 508. IR (KBr): 1667, 1596, 1474,
1380, 1256, 761. 1H-NMR: 1.26 (d, J ˆ 6.3, 3 H); 1.90 ± 2.00 (m, 2 H); 2.65 ± 2.75 (m, 2 H); 2.78 ± 2.96 (m, 1 H);
3.66 ± 3.81 (m, 2 H); 3.98 ± 4.08 (m, 2 H); 6.88 ± 7.08 (m, 3 H). 13C-NMR: 15.7; 21.5; 27.2; 33.2; 35.2; 41.1; 122.2;
124.9; 125.0; 125.8; 127.6; 135.9; 172.4. Anal. calc. for C13H15NO (201.26): C 77.58, H 7.51, N 6.96; found: C 77.86,
H 7.26, N 7.05.
5,6-Dihydro-1-phenyl-4H-pyrrolo[3,2,1-ij]quinolin-2(1H)-one (6b). M.p. 124 ± 1258. IR (KBr): 1706, 1625,
1600, 1480, 1345, 1240, 767. 1H-NMR: 2.04 (dd, J ˆ 0.9, 7.8, 2 H); 2.81 (t, J ˆ 5.3, 2 H); 3.66 ± 3.86 (m, 2 H); 4.61
(s, 1 H); 6.91 ± 7.39 (m, 8 H). 13C-NMR: 21.2; 24.6; 39.1; 52.9; 120.2; 122.1; 122.7; 127.3; 127.4; 128.4; 128.8; 136.5;
140.33; 174.9. Anal. calc. for C17H15NO (249.30): C 81.90, H 6.06, N 5.62; found: C 81.76, H 6.16, N 5.39.
2,3-Dihydro-1-(2-methyl-1-oxoprop-2-enyl)-1H-indole (7c). M.p. 66.5 ± 678. IR (KBr): 1655, 1631, 1594,
1482, 1449, 1415, 1392, 1254, 772. 1H-NMR: 2.04 (br. s, 3 H); 3.10 (t, J ˆ 8.3, 2 H); 4.09 (t, J ˆ 8.3, 2 H); 5.25 (br.

Helvetica Chimica Acta ± Vol. 83 (2000)
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s, 1 H); 5.33 (d, J ˆ 1.3, 1 H); 6.98 ± 7.05 (m, 1 H); 7.15 ± 7.27 (m, 3 H). 13C-NMR: 19.8; 27.9; 49.7; 116.7; 123.9;
124.9; 127.3; 132.4; 141.8; 142.3; 169.9. Anal. calc. for C12H13NO (187.23): C 76.97, H 7.00, N 7.48; found: C 76.75,
H 7.05, N 7.34.
1,2,5,6-Tetrahydro-5-methyl-4H-pyrrolo[3,2,1-ij]quinolin-4-one (8c). B.p. 1708/2 Torr. IR (film): 1667, 1595,
1485, 1393, 764. 1H-NMR: 1.29 (d, J ˆ 6.6, 3 H); 2.63 ± 2.77 (m, 2 H); 2.97 ± 3.09 (m, 1 H); 3.14 ± 3.22 (m, 2 H);
3.97 ± 4.17 (m, 2 H); 6.88 ± 7.08 (m, 3 H). 13C-NMR: 16.2; 27.7; 32.5; 36.3; 45.2; 119.8; 123.0; 123.1; 125.3; 128.6;
‡
141.0; 170.6. MS: 187 (100, M ), 172 (14), 159 (23), 144 (35), 130 (21), 117 (12). Anal. calc. for C12H13NO
(187.23): C 76.97, H 7.00, N 7.48; found: C 76.82, H 7.16, N 7.25.
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Received March 18, 2000