Palladium-catalyzed cross-benzannulation of aminoenynes with diynes. Highly regioselective synthesis of polysubstituted anilines

Article abstract of DOI:10.1021/jo000171m

Polysubstituted anilines were prepared by the palladium-catalyzed cross- benzannulation of conjugated aminoenynes 1-4 with diynes 8. The reaction proceeded in a highly regioselective manner under mild conditions, and the anilines were obtained as single regioisomers. Our method complements the well-known precedures for the preparation of polysubstituted anilines which are widely used in organic synthesis.

Full text of DOI:10.1021/jo000171m

4338
J . Org. Chem. 2000, 65, 4338-4341
P a lla d iu m -Ca ta lyzed cr oss-Ben za n n u la tion of Am in oen yn es w ith
Diyn es. High ly Regioselective Syn th esis of P olysu bstitu ted
An ilin es
Shinichi Saito,† Naoyuki Uchiyama,‡ Vladimir Gevorgyan,‡ and Yoshinori Yamamoto*,‡
Institute for Chemical Reaction Science, Tohoku University, Sendai, 980-8578, J apan, and Department of
Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, J apan
Received February 7, 2000
Polysubstituted anilines were prepared by the palladium-catalyzed cross-benzannulation of
conjugated aminoenynes 1-4 with diynes 8. The reaction proceeded in a highly regioselective
manner under mild conditions, and the anilines were obtained as single regioisomers. Our method
complements the well-known precedures for the preparation of polysubstituted anilines which are
widely used in organic synthesis.
The preparation of polysubstituted anilines has been
mainly achieved by classic synthetic methods such as
electrophilic nitration followed by the reduction of the
resulting nitro group (eq 1).1 However, the usefulness of
common characteristic in that the reaction proceeds in a
highly regiocontrolled manner, and only a single isomer
has been isolated in most examples. In our continuing
study on benzannulation reactions, it occurred to us that
the use of aminoenynes must lead to the formation of
polysubstituted anilines. In this paper we report that the
regioselective synthesis of polysubstituted anilines is
accomplished by the cross-benzannulation reaction of
aminoenynes with diynes (eq 4)
the reaction is limited by the severe reaction conditions
required for the nitration in many examples. An alterna-
tive synthetic method is the nucelophilic amination of
the aromatic ring.2 This method has been restricted by
the fact that the reaction proceeds only with electron-
deficient benzenes. This restriction has been removed by
the recent excellent development of the transition metal-
catalyzed amination of halobenzenes (eq 2).2,3
Recently, we discovered palladium-catalyzed homo-
benzannulation of conjugated enynes4 and cross-benzan-
nulation of conjugated enynes and diynes (eq 3),5 and
these new reactions have been applied to the synthesis
of polysubstituted aromatic compounds as well as cyclo-
phanes and phenols.6 These reactions have a notable
Resu lts a n d Discu ssion
P r ep a r a tion of Am in oen yn es. The aminoenynes
were prepared by the procedure described in Schemes 1
and 2. Thus, compound 6 was prepared from L-serine in
four steps,6,7 and 6 was treated with 4 equiv of n-BuLi
to yield 7. Dianion 7 was protonated to give the 2-ami-
noenyne 1 in good yield (64% from 6).8 Though we
expected that the monomethylation of 7 would proceed
in a highly chemoselective manner in the presence of 1
equiv of iodomethane, the methylation did not proceed
† Institute for Chemical Reaction Science.
‡ Department of Chemistry.
(1) March, J . Advanced Organic Chemistry; Wiley: New York, 1992;
pp 1216-1217.
(2) Review: Belfield, A. J .; Brown, G. R.; Foubister, A. J . Tetrahe-
dron 1999, 55, 11399-11428, and references therein.
(3) Reviews: (a) Hartwig, J . Synlett 1997, 329-340. (b) Hartwig, J .
Angew. Chem., Int. Ed. 1998, 37, 2046-2067. (c) Wolfe, J . P.; Wagaw,
S.; Marcoux, J .-F.; Buchwald, S. L. Acc. Chem. Res. 1998, 31, 805-
818. (d) Yang, B. H.; Buchwald, S. L. J . Organomet. Chem. 1999, 576,
125-146.
(4) Saito, S.; Salter, M. M.; Gevorgyan, V.; Tsuboya, N.; Tando, K.;
Yamamoto, Y. J . Am. Chem. Soc. 1996, 118, 3970-3971.
(5) (a) Gevorgyan, V.; Takeda, A.; Yamamoto, Y. J . Am. Chem. Soc.
1997, 119, 11313-11314. (b) Gevorgyan, V.; Takeda, A.; Homma, M.;
Sadayori, N.; Radhakrishnan, U.; Yamamoto, Y. J . Am. Chem. Soc.
1999, 121, 6391-6402.
(7) (a) Garner, P.; Park, J . M. Organic Syntheses; Wiley: New York,
1998; Collect. Vol. IX, pp 300-305. (b) Garner, P. Tetrahedron Lett.
1984, 25, 5855-5858.
(8) The formation of this compound has been briefly mentioned in
the literature. See: Reginato, G.; Mordini, A.; Degl’Innocenti, A.;
Caracciolo, M. Tetrahedron Lett. 1995, 36, 8275-8278.
(6) Reviews: Gevorgyan, V.; Yamamoto, Y. J . Organomet. Chem.
1999, 576, 232-247. Saito, S.; Yamamoto, Y. Chem. Rev., in press.
10.1021/jo000171m CCC: $19.00 © 2000 American Chemical Society
Published on Web 06/17/2000

Aminoenyne-Diyne Pd-Catalyzed cross-Benzannulation
J . Org. Chem., Vol. 65, No. 14, 2000 4339
Ta ble 1. Syn th esis of P olysu bstitu ted An ilin es
Sch em e 1
aminoenyne
R1 R2
1 H
diyne
R3
isolated
condition product yield (%)
entry
1
2
3
4
5
6
7
H
n-Bu (8a ) rt, 1.5 ha
9a
9b
9c
10a
11a
11b
12a
53
37
60
40
62
64
59
Ph (8b)
rt, 1.5 ha
Me (8c) rt, 1.5 ha
n-Bu (8a ) 60 °C, 46 h
n-Bu (8a ) 60 °C, 80 h
2 Me H
3 Me Me
Ph (8b)
rt, 68 h
Sch em e 2
4 b
N(Bn)Ts n-Bu (8a ) 100 °C, 15 h
a
A solution of aminoenyne was added dropwise (1.5 h) to a
b
solution of the catalyst. For the structure of 4, see Scheme 2.
Ta ble 2. Dep r otection of Eth yn yl An ilin es
as we expected and the yield of 2 was low (9%): N,4-
dimethyl-2-aminoenyne 3 was isolated as the major
product (25%). Compound 3 was prepared in 55% yield
when 7 was treated with 2 equiv of iodomethane. We also
prepared diaminoenyne 4 by palladium(II)-catalyzed
dimerization9 of alkyne 5, which was recently prepared
from N-benzyl-p-toluenesulfonamide by Witulski et al.10
These conjugated enynes were subjected to the cross-
benzannulation reaction with conjugated diynes.
ethynyl-
aniline
isolated
yield (%)
entry
R1
R2
R3
Ph
n-Bu
Ph
product
Ben za n n u la tion of Am in oen yn es w ith Diyn es.
Though the homo-benzannulation (cyclodimerization) of
the aminoenyne 1 did not proceed in the presence of
palladium catalyst, we found that some aminoenynes
reacted with diynes smoothly in the presence of a Pd(0)
catalyst. The results of the reactions of aminoenynes with
diynes are summarized in Table 1. Thus, aminoenyne 1
reacted with diynes 8 in the presence of Pd2(dba)3‚CHCl3
(5 mol %) and (o-tolyl)3P (40 mol %) in toluene at rt to
give the 1,3,4-trisubstituted anilines in good yields (Table
1, entries 1-3). It was necessary to add the enyne slowly
to the solution, since the decomposition of 1 was observed
in the presence of Pd(0) catalyst. The isolated yield of
9b was lower (entry 2), probably because of the lower
reactivity of diphenylbutadiyne 8b compared to that of
dialkylbutadiynes (8a and 8c, entries 1 and 3). The
reactions of polysubstitued aminoenynes 2-3 were car-
ried out simply by heating a mixture of aminoenyne,
diyne, Pd2(dba)3‚CHCl3 (5 mol %), and (o-tolyl)3P (40 mol
%) in toluene; the substituted aminoenynes were more
stable compared to 1. However, the reactivity of these
enynes was lower, and it was necessary to carry out the
reaction at higher temperatures or for a longer time
(Table 1, entries 4-6). The decreased reactivity of 2,4-
disubstituted enynes compared to that of 2-substituted
enynes in the benzannulation reaction has already been
reported,5b and our present results are in agreement with
1
2
3
9b
11a
11b
H
Me
Me
H
Me
Me
13
14
15
78
79
52
the previous findings. The reaction of diaminoenyne 4
with diyne also proceeded at elevated temperatures (100
°C) in the presence of Pd(PPh3)4 (5 mol %) and TDMPP
(tris(2,6-dimethoxyphenyl)phosphine, 20 mol %)11 to give
polysubstituted diaminobenzene 12a in good yield (59%,
entry 7). It is possible to explain the lower reactivity of
4 in terms of the incresed steric bulkiness of the sub-
strate. In all examples, only a single regioisomer was
obtained as the product and no isomeric anilines were
isolated.
We also succeeded in the deprotection of the Boc group
attached to the amino group. Though the deprotection
of the Boc group was unsuccessful when the anilines were
treated with HCl or TFA, we succeded in removing the
Boc group by simply heating 9b at elevated temperature
(185 °C) in diphenyl ether (Table 2, entry 1).12 Other
substituents attached to the benzene ring were inert
under this reaction condition. The deprotection of other
anilines such as 11a and 11b also proceeded smoothly
at this temperature, and the corresponding deprotected
anilines were isolated in good yields (entries 2 and 3).
(11) Gevorgyan, V.; Sadayori, N.; Yamamoto, Y. Tetrahedron Lett.
1997, 38, 8603-8604.
(12) (a) Wasserman, H. H.; Berger, G. D.; Cho, K. R. Tetrahedron
Lett. 1982, 23, 465-468. (b) Rawal, V. H.; J ones, R. J .; Caba, M. P. J .
Org. Chem. 1987, 52, 19-28.
(9) Trost, B. M.; Sorum, M. T.; Chan, C.; Harms, A. E.; Ru¨hter, G.
J . Am. Chem. Soc. 1997, 119, 698-708.
(10) Witulski, B.; Stengel, T. Angew. Chem., Int. Ed. 1998, 37, 7,
489-492.

4340 J . Org. Chem., Vol. 65, No. 14, 2000
Saito et al.
2H, J ) 8.3 Hz), 7.56 (d, 2H, J )8.3 Hz), 7.28-7.19 (m, 12H),
7.07-7.03 (m, 4H), 5.47 (s, 1H), 5.25 (s, 1H), 4.27 (s, 2H), 4.20
(s, 2H), 2.43 (s,3H), 2.37 (s, 3H); 13C NMR 144.8, 143.5, 135.9,
135.8, 134.6, 134.0, 129.7, 129.5, 129.4, 128.49, 128.46, 128.2,
127.7, 127.6, 127.4, 125.5, 125.0, 84.0, 66.7, 55.3, 51.4, 21.7,
Con clu sion
We developed palladium-catalyzed cross-benzannula-
tion of aminoenynes with diynes. This reaction proceeded
with high regioselectivity under relatively mild reaction
conditions. Our method complements the well-known
precedures for the preparation of polysubstituted anilines
which are widely used in organic synthesis.
21.6 (one signal is missing); IR (KBr) 2237, 1618, 1595 cm-1
HRMS calcd for C32H30N2O4S2 570.1647, found 570.1622.
;
Cr oss-Ben za n n u la tion of Con ju ga ted En yn es w ith
Diyn es. Gen er a l P r oced u r e. To a solution of diyne (0.1
mmol), Pd2dba3‚CHCl3 (5.2 mg, 5 mol %), and (o-tolyl)3P (12
mg, 40 mol %) in dry toluene (0.1 mL) was slowly added a
solution of enyne (0.1 mmol) in toluene (0.1 mL). After the
addition was complete, the reaction mixture was passed
through a short silica gel column, followed by purification of
the residue by column chromatography (eluent: hexane:AcOEt
) 20:1).
ter t-Bu t yl 3-m et h yl-4-(1-p r op yn yl)p h en ylca r b a m a t e
(9a ): light yellow wax; 1H NMR 7.20 (d, 1H, J ) 8.3 Hz), 7.19
(d, 1H, J ) 2.0 Hz), 6.98 (dd, 1H, J ) 8.3, 2.0 Hz), 6.36 (s,
1H), 2.31 (s, 3H), 2.00 (s, 3H), 1.44 (s, 9H); 13C NMR 152.5,
141.0, 137.5, 132.5, 119.0, 118.3, 115.4, 88.5, 80.7, 78.3, 28.3,
20.9, 4.4; IR (KBr) 3325, 1692, 1655, 1585, 1522 cm-1; HRMS
calcd for C15H19NO2 245.1415, found 245.1400.
Exp er im en ta l Section
Gen er a l In for m a tion . The dry solvents were purchased
from Wako chemicals (J apan) and used as such. Reactions
were performed under Ar in oven-dried apparatus. (R)-(-)-
2,2-Dimethyl-3-tert-butoxycarbonyl-4-(â,â-dibromovinyl)oxazo-
lidine 56,7 and 1-benzyl-1-ethynyltosylamide 1610 were pre-
pared according to the literature.
2-ter t-Bu toxyca r bon yla m in o-1-bu ten -3-yn e (1). To a
solution of 5 (3.85 g, 10 mmol) in dry THF (100 mL) was slowly
n
added a 1.56 M solution of BuLi in hexane (26 mL, 4 equiv)
at -78 °C under Ar, and the mixture was kept stirring at -78
°C for 30 min. The temperature of the mixture was slowly
raised to rt, and water was added. The mixture was extracted
with ether, and the combined organic layer was washed with
brine, dried over MgSO4, and evaporated. The crude product
was further purified by column chromatography to give the
pure compound as a light yellow wax (1.07 g, 64%): 1H NMR
δ 5.96 (s, 1H), 5.77 (s, 1H), 5.00 (s, 1H), 2.83 (s, 1H), 1.44 (s,
9H); 13C NMR δ 152.2, 123.0, 106.3, 80.8, 80.2, 75.4, 28.2; IR
(neat) 3298, 2108, 1728, 1616, 1504 cm-1; HRMS calcd for
C9H13NO2 167.0946, found 167.0908.
ter t-Bu tyl 3-bu tyl-4-(1-h exyn yl)p h en ylca r ba m a te (9b):
1
colorless oil; H NMR 7.20 (d, 1H J ) 8.3 Hz), 7.14 (d, 1H, J
) 2.0 Hz), 7.00 (dd, 1H J ) 8.2, 2.0 Hz), 6.40 (s, 1H), 2.64 (t,
2H J ) 7.9 Hz), 2.36 (t, 2H, J ) 6.8 Hz), 1.57-1.18 (m, 8H),
1.44 (s, 9H), 0.87 (t, 3H J ) 7.0 Hz), 0.86 (t, 3H, J ) 7.3 Hz);
13C NMR 152.5, 145.8, 137.6, 132.7, 118.2, 117.9, 115.4, 92.6,
80.5, 79.0, 34.6, 32.8, 31.0, 28.3, 22.6, 22.0, 19.2, 14.0, 13.6;
IR (neat) 3333, 1732, 1703, 1611, 1583 cm-1; HRMS calcd for
C
21H31NO2 329.2353, found 329.2350.
2-ter t-Bu toxyca r bon yla m in o-1-p en ten -3-yn e (2). To a
solution of 5 (1.93 g, 5 mmol) in dry THF (12.8 mL) was slowly
added a 1.56 M solution of nBuLi in hexane (12.8 mL, 4 equiv)
at -78 °C under Ar, and the mixture was kept stirring at -78
°C for 30 min. The temperature of the mixture was raised to
-15 °C, and MeI (0.312 mL, 1 equiv) was slowly added to the
mixture, which was kept sitrring for 1 night. Water was added,
and the mixture was extracted with ether. The combined
organic layer was washed with brine, dried over MgSO4, and
evaporated. The crude product was further purified by flash
column chromatography to give the pure compound as a white
solid (80 mg, 9%). Dimethylated compound 8 (243 mg, 1.25
mmol, 25%) was also isolated. Compound 7: 1H NMR δ 5.91
ter t-Bu tyl 3-p h en yl-4-(p h en yleth yn yl)p h en ylca r ba m -
1
a te (9c): colorless oil; H NMR 7.57-7.14 (m, 13H), 6.61 (s,
1H), 1.42 (s, 9H); 13C NMR 152.4, 144.8, 140.2, 138.5, 133.6,
131.1, 129.3, 128.2, 127.8 (overlap?), 127.5, 123.6, 119.0, 116.9,
115.9, 91.3, 89.4, 80.9, 28.3; IR (neat) 3302, 1697 1589, 1574
cm-1; HRMS calcd for C25H23NO2 369.1729, found 369.1721.
ter t-Bu t yl 3-b u t yl-4-(1-h exyn yl)-5-m et h ylp h en ylca r -
ba m a te (10a ): colorless oil; 1H NMR 7.06 (s, 1H), 7.00 (s, 1H),
6.39 (s, 1H), 2.71 (t, 2H, J ) 7.9 Hz), 2.48 (t, 2H, J ) 6.8 Hz),
2.38 (s, 3H), 1.62-1.26 (m, 8H), 1.51(s, 9H), 0.95 (t, 3H, J )
7.0 Hz), 0.93(t, 3H, J ) 7.1 Hz); 13C NMR 152.5, 145.8, 141.1,
136.8 118.0, 116.5, 115.7, 97.1, 80.4, 77.7, 34.9, 32.8, 31.2, 28.4,
22.7, 22.0, 21.3, 19.4, 14.0, 13.6; IR (neat) 3337, 1730, 1701,
1607, 1589 cm-1; HRMS calcd for C22H33NO2 343.2501, found
343.2495.
(s, 1H), 5.68 (s, 1H), 4.84 (s, 1H), 1.92 (s, 3H), 1.47 (s,9H); 13
C
NMR 1523, 124.1, 103.5, 83.8, 80.5, 76.7, 28.3, 3.9; IR (neat)
3329, 2243, 1719, 1618, 1508, 1458 cm-1; HRMS calcd for
ter t-Bu tyl [3-bu tyl-4-(1-h exyn yl)-5-m eth ylp h en yl]-N-
m eth ylca r ba m a te (11a ): colorless oil; 1H NMR 6.89 (s, 1H),
6.87 (s, 1H), 3.22 (s, 3H), 2.73 (t, 2H, J ) 7.9 Hz), 2.49 (t, 2H,
J ) 6.9 Hz), 2.39 (s, 3H), 1.63-1.57 (m, 4H), 1.51 (m, 2H),
1.44 (s, 9H), 1.38 (q, 2H, J ) 7.7 Hz), 0.96 (t, 3H, J ) 7.7 Hz),
0.94 (t, 3H, J ) 7.7 Hz); 13C NMR 154.6, 145.1, 142.2, 140.4,
123.3, 122.9, 120.3, 97.9, 80.1, 77.6, 37.2, 34.7, 32.7, 31.0, 28.2,
C
10H15NO2 181.1103, found 181.1111.
2-(N-ter t-Bu toxyca r bon yl-N-m eth yla m in o)-1-p en ten -3-
yn e (3). To a solution of 5 (1.93 g, 5 mmol) in dry THF (12.8
mL) was slowly added a 1.56 M solution of nBuLi in hexane
(12.8 mL, 4 equiv) at -78 °C under Ar, and the mixture was
kept stirring at -78 °C for 30 min. The temperature of the
mixture was raised to -15 °C, and MeI (0.624 mL, 2 equiv)
was slowly added to the mixture, which was kept sitrring for
1 night. Water was added, and the mixture was extracted with
ether. The combined organic layer was washed with brine,
dried over MgSO4, and evaporated. The crude product was
further purified by flash column chromatography to give the
pure compound as a light yellow wax (0.538 g, 55%): 1H NMR
5.22 (d, 2H, J ) 5.4 Hz), 3.06 (s, 3H), 1.96 (s, 3H), 1.48 (s,
9H); 13C NMR 154.0, 130.7, 114.7, 85.0, 80.2, 76.5, 35.4, 28.1,
22.6, 21.9, 21.2, 19.3, 13.9, 13.6; IR (neat) 1701, 1603 cm-1
.
Anal. Calcd for C23H35NO2: C, 77.27; H, 9.87; N, 3.92. Found:
C, 77.53; H, 10.02; N, 3.89.
ter t-Bu tyl [3-m eth yl-5-p h en yl-4-(p h en yleth yn yl)p h e-
n yl]-N-m eth ylca r ba m a te (11b): colorless oil; 1H NMR 7.62
(d, 2H, J ) 7.5 Hz), 7.45-7.19 (m, 8H), 7.14 (d, 2H, J ) 5.0
Hz), 3.27 (s, 3H), 2.57 (s, 3H), 1.48 (s, 9H); 13C NMR 154.4,
144.5, 143.1, 141.1, 140.7, 131.0, 129.3, 128.1, 127.9, 127.7,
127.4, 124.8, 123.6,123.5, 118.3, 96.4, 87.7, 80.5, 37.0, 28.3,
3.9; IR (neat) 2239, 1701, 1616 cm-1; HRMS calcd for C11H17
NO2 195.1258, found 195.1264.
-
21.4; IR (neat) 1701, 1595, 1566 cm-1; HRMS calcd for C27H27
NO2 397.2042, found 397.2052.
-
2,4-Bis(N-p-tolu en esu lfon yl-N-ben zyla m in o)-1-p en ten -
3-yn e (4). To a mixture of Pd(OAc)2 (8.1 mg, 36 µmol) and
TDMPP (16 mg, 36 µmol) in dry benzene (1.8 mL) was added
a solution of 1-benzyl-1-ethynyltosylamide 16 (0.514 g, 1.8
mmol) in dry benzene (3.6 mL) at rt under Ar, and the mixture
was kept stirring at rt for one night. The mixture was passed
through a short silica gel column (basic), and the eluent was
evapoated to give the crude product. The product was further
purified by silica gel column chromatography (basic) to give 4
(0.257 g, 50%): white solid: mp 99-105 °C; 1H NMR 7.67 (d,
1,3-Bis[b en zylt osyla m in o]-4-(1-h exyn yl)-5-b u t ylb en -
zen e (12a ): colorless oil; H NMR 7.42 (d, 2H, J ) 8.3 Hz),
1
7.40(d, 2H J ) 8.1 Hz), 7.26-7.08 (m, 14H), 6.70 (d, 1H J )
2.2 Hz), 6.66 (d, 1H, J ) 2.2 Hz), 4.77 (s, 2H), 4.52 (s, 2H),
2.47 (t, 2H, J ) 7.6 Hz), 2.43 (s, 3H), 2.41 (s, 3H), 2.18 (t, 2H,
J ) 6.5 Hz), 1.45-1.36 (m, 4H), 1.28-1.18 (m, 2H), 1.07-0.97
(m, 2H), 0.92 (t, 3H, J ) 7.1 Hz), 0.81 (t, 3H, J ) 7.2 Hz); 13
C
NMR 146.6, 143.4, 142.9, 139.8, 137.3, 136.9, 136.3, 135.4,
135.2, 129.9, 129.6, 129.2, 129.0, 128.8, 128.24, 128.20, 128.1,
127.7, 127.6, 127.5, 127.4, 123.6, 100.4, 75.4, 54.0, 53.8, 34.1,

Aminoenyne-Diyne Pd-Catalyzed cross-Benzannulation
J . Org. Chem., Vol. 65, No. 14, 2000 4341
32.1, 30.5, 22.1, 21.9, 21.62, 21.55, 19.4, 14.0, 13.6; IR (neat)
1599 cm-1; HRMS calcd for C44H48N2O4S2 732.3056, found
732.3063.
2H, J ) 6.8 Hz), 2.34 (s, 3H), 1.65-1.32 (m, 8H), 0.94 (t, 3H,
J ) 7.2 Hz), 0.93 (t, 3H, J ) 7.3 Hz); 13C NMR 148.1, 146.1,
141.3, 112.1, 110.8, 110.1, 95.2, 78.3, 35.0, 32.9, 31.3, 30.6, 22.8,
22.0, 21.4, 19.4, 14.0, 13.6; IR (neat) 3414, 1609 cm-1; HRMS
calcd for C18H27N 257.2143, found 257.2137.
3,N-Dim eth yl-5-p h en yl-4-(p h en yleth yn yl)a n ilin e (13):
colorless oil; 1H NMR 7.64 (m, 2H), 7.46-7.34 (m, 3H), 7.23-
7.20 (m, 5H), 6.48 (d, 1H, J ) 3.6 Hz), 6.47 (d, 1H, J ) 2.2
Hz), 3.88 (s, 1H), 2.87 (s, 3H), 2.53 (s, 3H); 13C NMR 148.8,
145.7, 142.2, 141.6, 130.7, 129.4, 128.1, 127.6, 127.2, 127.1,
124.5, 112.3, 110.7, 110.1, 94.3, 89.2, 30.4, 21.6; IR (neat) 3420,
2203, 1607 cm-1; HRMS calcd for C22H19N 297.1517, found
297.1497.
3-P h en yl-4-(p h en yleth yn yl)a n ilin e (15): colorless oil; 1H
NMR 7.59-7.56 (m, 2H), 7.39-7.15 (m, 9H), 6.64 (d, 1H, J )
2.4 Hz), 6.57 (dd, 1H, J ) 8.5, 2.4 Hz), 3.80 (s, 2H); 13C NMR
146.7, 145.3, 140.7, 134.2, 131.0, 129.2, 128.1, 127.8, 127.4,
124.1, 115.7, 113.7, 111.2, 90.1, 90.0 (one signal will be
overlapped); IR (neat) 3476, 3383, 3213, 2205, 1620, 1595 cm-1
HRMS calcd for C20H15N 269.1204, found 269.1206.
;
5,N-Dim eth yl-3-bu tyl-4-(1-h exyn yl)a n ilin e (14): color-
less oil; 1H NMR 6.27 (d, 1H, J ) 2.2 Hz), 6.25 (d, 1H, J ) 2.3
Hz), 3.63 (s, 1H), 2.80 (s, 3H), 2.68 (t, 2H, J ) 7.8 Hz), 2.46 (t,
J O000171M