CuI/4-hydro-L-proline as a more effective catalytic system for coupling of aryl bromides with N-boc hydrazine and aqueous ammonia

Article abstract of DOI:10.1021/jo9006738

(Chemical Equation Presented) CuI/4-hydroxy-L-proline-catalyzed coupling of aryl bromides and N-Boc hydrazine takes place in DMSO at 80°C to give N-aryl hydrazides. When aryl iodides are employed, this reaction completes at 50°C and no ligand is required. Under the catalysis of CuI/4-hydroxy-L- proline, the coupling reaction of aqueous ammonia with aryl bromides proceeds smoothly at 50°C to afford primary arylamines. In this case K ₂CO₃ is found as a better base than Cs₂CO ₃. These processes allow assembly of N-aryl hydrazides and primary arylamines that bear a wide range of functional groups including hydroxyl, amine, trifluoromethyl, ester, nitro, and ketone.

Full text of DOI:10.1021/jo9006738

CuI/4-Hydro-L-proline as a More Effective Catalytic System for
Coupling of Aryl Bromides with N-Boc Hydrazine and Aqueous
Ammonia
Liqin Jiang,† Xu Lu,‡ Hui Zhang,‡ Yongwen Jiang,† and Dawei Ma*,†
State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic
Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China, and Department of
Chemistry, Shanghai UniVersity, Shanghai 200444, China
madw@mail.sioc.ac.cn
ReceiVed April 8, 2009
CuI/4-hydroxy-L-proline-catalyzed coupling of aryl bromides and N-Boc hydrazine takes place in DMSO
at 80 °C to give N-aryl hydrazides. When aryl iodides are employed, this reaction completes at 50 °C
and no ligand is required. Under the catalysis of CuI/4-hydroxy-L-proline, the coupling reaction of aqueous
ammonia with aryl bromides proceeds smoothly at 50 °C to afford primary arylamines. In this case
K2CO3 is found as a better base than Cs2CO3. These processes allow assembly of N-aryl hydrazides and
primary arylamines that bear a wide range of functional groups including hydroxyl, amine, trifluoromethyl,
ester, nitro, and ketone.
Introduction
give poor yields in cases of electron-rich substrates.5,6 As a
continuing effort on exploring amino acid-promoted Ullmann-
type reactions,1e,7 we found that using 4-hydroxy-L-proline as
a ligand could solve the above problems, leading to coupling
Recently, great progress has been made in copper-catalyzed
C-N bond formation between aryl halides and N-containing
nucleophiles.1 The use of special ligands makes this transforma-
tion work under significantly milder conditions compared with
those for the traditional Ullmann reaction.2 This progress has
greatly expanded the reaction scope because more N-containing
nucleophiles could be employed as coupling partners. For
example, Buchwald3 and Kwong4 subsequently reported that
coupling of hydrazides with aryl iodides took place under the
catalysis of CuI/1,10-phenanthroline or CuI/picolinic acid to
afford N-aryl hydrazides, while Chang5 described that am-
monium salts and aqueous NH3 could be used for coupling with
aryl halides to deliver primary arylamines. However, in their
reports, aryl bromides were not examined3,4 or were found to
(2) For selected examples on ligand-promoted Ullmann-type amination, see:
(a) Ma, D.; Zhang, Y.; Yao, J.; Wu, S.; Tao, F. J. Am. Chem. Soc. 1998, 120,
12459. (b) Ma, D.; Xia, C. Org. Lett. 2001, 3, 2583. (c) Klapars, A.; Antilla,
J. C.; Huang, X.; Buchwald, S. L. J. Am. Chem. Soc. 2001, 123, 7727. (d)
Gujadhur, R. K.; Bates, C. G.; Venkataraman, D. Org. Lett. 2001, 3, 4315. (e)
Antilla, J. C.; Klapars, A.; Buchwald, S. L. J. Am. Chem. Soc. 2002, 124, 11684.
(f) Kwong, F. Y.; Buchwald, S. L. Org. Lett. 2003, 5, 793. (g) Ma, D.; Cai, Q.;
Zhang, H. Org. Lett. 2003, 5, 2453. (h) Cristau, H.-J.; Cellier, P. P.; Spindler,
J.-F.; Taillefer, M. Chem.sEur. J. 2004, 10, 5607. (i) Zhang, H.; Cai, Q.; Ma,
D. J. Org. Chem. 2005, 70, 5164. (j) Rao, H.; Jin, Y.; Fu, H.; Jiang, Y.; Zhao,
Y. Chem.sEur. J. 2006, 12, 3636. (k) Shafir, A.; Buchwald, S. L. J. Am. Chem.
Soc. 2006, 128, 8742. (l) Kantam, M. L.; Yadav, J.; Laha, S.; Sreedhar, B.; Jha,
S. AdV. Syn. Catal. 2007, 349, 1938. (m) Ma, H.; Jiang, X. J. Org. Chem. 2007,
72, 8943. (n) Chen, W.; Zhang, Y.; Zhu, L.; Lan, J.; Xie, R.; You, J. J. Am.
Chem. Soc. 2007, 129, 13879. (o) Zou, B.; Yuan, Q.; Ma, D. Angew. Chem.,
Int. Ed. 2007, 46, 2598. (p) Zou, B.; Yuan, Q.; Ma, D. Org. Lett. 2007, 9, 4291.
(q) Mao, J.; Guo, J.; Song, H.; Ji, S. Tetrahedron 2008, 64, 2471. (r) Maheswaran,
H.; Krishna, G. G.; Prasanth, K. L.; Srinivas, V.; Chaitanya, G. K.; Bhanuprakash,
K. Tetrahedron 2008, 64, 2471.
† Chinese Academy of Sciences.
‡ Shanghai University.
(1) For reviews, see: (a) Ley, S. V.; Thomas, A. W. Angew. Chem., Int. Ed.
2003, 42, 5400. (b) Beletskaya, I. P.; Cheprakov, A. V. Coord. Chem. ReV. 2004,
248, 2337. (c) Monnier, F.; Taillefer, M. Angew. Chem., Int. Ed. 2008, 47, 3096.
(d) Evano, G.; Blanchard, N.; Toumi, M. Chem. ReV. 2008, 108, 3054. (e) Ma,
D.; Cai, Q. Acc. Chem. Res. 2008, 41, 1450.
(3) Wolter, M.; Klapars, A.; Buchwald, S. L. Org. Lett. 2001, 3, 3803.
(4) Lam, M. S.; Lee, H. W.; Chen, A. S. C.; Kwong, F. Y. Tetrahedron
Lett. 2008, 49, 6192.
(5) Kim, J.; Chang, S. Chem. Commun. 2008, 3052.
4542 J. Org. Chem. 2009, 74, 4542–4546
10.1021/jo9006738 CCC: $40.75 2009 American Chemical Society
Published on Web 05/11/2009

CuI/4-Hydroxy-L-proline-Catalyzed Coupling of Bromides
TABLE 1. CuI-Catalyzed Coupling of 4-Bromoanisole with N-Boc
TABLE 2. CuI/4-Hydroxy-L-proline-Catalyzed Coupling of Aryl
Hydrazine in the Presence of Different Ligandsa
Bromides with N-Boc Hydrazinea
entry
ligand
yield (%)
1
2
3
4
5
1,10-phenanthroline
picolinic acid
L-proline
N,N-dimethylglycine
4-hydroxy-L-proline
49
67
80
71
88
a Reaction conditions: 1a (1 mmol), 2a (2 mmol), CuI (0.1 mmol),
ligand (0.2 mmol), Cs2CO3 (2 mmol), DMSO (1 mL), 80 °C, 24 h.
of aryl bromides with N-Boc hydrazine, and aqueous ammonia
proceeded smoothly to afford N-arylation products in good
yields. Herein, we wish to report our results.
Results and Discussion
As indicated in Table 1, we began our studies by conducting
a CuI-catalyzed coupling reaction of 4-bromoanisole with N-Boc
hydrazine in the presence of different ligands. It was found that
at 80 °C after 24 h 1,10-phenanthroline gave the coupling
product 3a in 49% yield (entry 1). Improved yields were
observed by changing the ligand to picolinic acid, L-proline,
and N,N-dimethylglycine (entries 2-4), while the best result
was obtained when 4-hydroxy-L-proline was employed
(entry 5).
The combination of CuI and 4-hydroxy-L-proline was then
examined with different aryl bromides to explore the reaction
scope (Table 2). Generally, both electron-rich and electron-
deficient aryl bromides worked well, providing the correspond-
ing coupling products in good to excellent yields. Several
functional groups including hydroxyl, amine, trifluoromethyl,
ester, and aromatic heterocycles were found to tolerate our
conditions, thereby giving N-aryl hydrazides in good diversity.
The yields for formation of 3n-p (entries 13-15) are superior
to those reported by Buchwald3 and Kwong4 with aryl iodides.
In the case of methyl 4-bromobenzoate as substrate, the reaction
completed at 50 °C and two N-arylation regioisomers 3g and
4a (Figure 1) were isolated in a ratio of about 1:1 (entry 6).
The poor selectivity might result from the two nitrogen species
of N-Boc hydrazine having similar reactivity toward the coupling
with more reactive aryl bromide. This result is inconsistent to
that observed in CuI/1,10-phenanthroline-catalyzed N-arylation,3
indicating that this copper-catalyzed coupling process could
dramatically change under different reaction conditions.
The encouraging results from aryl bromides prompted us to
check if the coupling of aryl iodides with N-Boc hydrazine could
work at relatively low reaction temperatures under the action
of the CuI/amino acid catalytic system. We were pleased to
find that the CuI/4-hydroxy-L-proline catalyzed coupling reaction
a Reaction conditions: 1a (1 mmol), 2a (2 mmol), CuI (0.1 mmol),
ligand (0.2 mmol), Cs2CO3 (2 mmol), DMSO (1 mL), 80 °C, 24 h. b 3g
and 4a were isolated in a ratio of about 9:11.
(6) During the preparation of this paper, an efficient procedure for coupling
of aryl bromides with aqueous ammonia (catalyzed by Cu(acac)2 and
CH3COCH2COCH3) was reported, see: Xia, N.; Taillefer, M. Angew. Chem.,
Int. Ed. 2009, 48, 337.
(7) For recent progress, see: (a) Liu, F.; Ma, D. J. Org. Chem. 2007, 72,
4844. (b) Chen, Y.; Xie, X.; Ma, D. J. Org. Chem. 2007, 72, 9329. (c) Chen,
Y.; Wang, Y.; Sun, Z.; Ma, D. Org. Lett. 2008, 10, 625. (d) Wang, B.; Lu, B.;
Jiang, Y.; Zhang, Y.; Ma, D. Org. Lett. 2008, 10, 2761. (e) Yuan, Q.; Ma, D. J.
Org. Chem. 2008, 73, 5159. (f) Li, L.; Wang, M.; Zhang, X.; Jiang, Y.; Ma, D.
Org. Lett. 2009, 11, 1309.
FIGURE 1. Structures of compounds 4a and 4b.
of 4-iodoanisole with N-Boc hydrazine proceeded smoothly to
give 3a in 92% yield after 2.5 h (Table 3, entry 1). Further
evaluation indicated that 4-hydroxy-L-proline was useless for
this transformation (compare entries 1 and 2). With CuI alone
as a catalyst, a number of para- and meta-substituted aryl iodides
J. Org. Chem. Vol. 74, No. 12, 2009 4543

Jiang et al.
TABLE 3. CuI-Catalyzed Coupling of Aryl Iodides with N-Boc
TABLE 4. CuI-Catalyzed Coupling of 4-Bromoanisole with
Aqueous Ammonia under Different Conditionsa
Hydrazinea
entry
reaction conditions
yield (%)
1
2
3
4
5
Cs2CO3/50 °C/24 h
Cs2CO3/70 °C/24 h
K2CO3/50 °C/24 h
K2CO3/50 °C/36 h
K2CO3/50 °C/36 h
48
71b
81
85
74c
a Reaction conditions: 1a (1 mmol), aqueous ammonia (28%, 1 mL),
CuI (0.2 mmol), 4-hydroxy-L-proline (0.4 mmol), base (3 mmol),
DMSO (2 mL). b 0.1 mmol CuI and 0.2 mmol 4-hydroxy-L-proline were
c
used. L-Proline was used as a ligand.
18), indicating that steric hindrance plays an important role for
this coupling reaction. Noteworthy is that Buchwald and co-
workers have mentioned that without addition of the 1,10-
phenanthroline ligand, the coupling reaction of aryl iodides with
N-Boc hydrazine occurred in some cases but slightly low yields
were observed.3 Our results demonstrated that DMSO is a better
solvent than DMF for this N-arylation.
Since 4-hydroxy-L-proline performed better than L-proline for
promoting CuI-catalyzed N-arylation,8 we next tried its applica-
tion in the coupling of aryl bromides with aqueous ammonia.
Accordingly, we chose the coupling of 4-bromoanisole and
aqueous ammonia as a model reaction to explore the optimized
reaction conditions. We were pleased to find that this reaction
proceeded at 50 °C to give 4-methoxybenzenamine in 48% yield
(Table 4, entry 1). Raising the reaction temperature to 70 °C
while reducing catalytic loading gave a better yield (entry 2).
Surprisingly, switching base to K2CO3 also improved the
reaction conversion dramatically (entry 3). Further improvement
could be achieved by prolonging the reaction time (entry 4).
Under the same conditions L-proline gave only 74% yield (entry
5), indicating that 4-hydroxy-L-proline is a more suitable ligand
for this transformation.
The established optimized reaction conditions were then tested
by varying aryl bromides and the results were summarized in
Table 5. It was found that both electron-donating and electron-
withdrawing substituents, no matter at the para-, meta- or ortho-
positions, are tolerated under these conditions. Remarkably,
several sterically hindered aryl bromides also afforded the
coupling products in good yields although the reaction temper-
ature should be increased to 70 °C to ensure the satisfactory
conversion (entries 9-14). When 1,4-dibromo-2-methylbenzene
was used, regioselective monoamination could be achieved as
is evident from 6p being isolated in 63% yield (entry 15).
In conclusion, we have revealed that 4-hydroxy-L-proline is
a powerful promoter for CuI-catalyzed N-arylation of aryl
bromides with N-Boc hydrazine and aqueous ammonia, leading
to reactions complete at 50-80 °C. A wide range of aryl
bromides bearing both electron-donating and electron-withdraw-
ing substituents were found applicable to these two coupling
reactions. In addition, coupling of aryl iodides with N-Boc
hydrazine was found to proceed well at 50 °C in DMSO in the
absence of any ligands. These new reaction conditions provide
more general procedures for assembly of N-aryl hydrazides and
primary arylamines from aryl halides. Considering that the
a Reaction conditions: 5 (1 mmol), 2 (1.2 mmol), CuI (0.05 mmol),
Cs2CO3 (1.5 mmol), DMSO (1 mL), 50 °C, 2.5-4 h. b 3n and 4b were
isolated in a ratio of about 3:1.
were examined and they generally worked well to afford
coupling products with a great diversity. When methyl 4-iodo-
benzoate was used, 3g was obtained as a single product in 90%
yield (entry 7), in contrast to the case of the corresponding
bromide as a substrate. Regioselectivity could be reached for
4-bromoiodobenzene, as is evident from 3s being isolated in
76% yield (entry 10). Poor yield was observed in the case of
4-iodonitrobenzene because some unidentified side products
were detected (entry 11). However, 3-iodonitrobenzene gave
the desired product in good yield (entry 15). When 2-iodotoluene
was used, a mixture of 3n and 4b (Figure 1) was obtained (entry
(8) This ligand has showed some advantages in our previous studies, see:
Xie, X.; Chen, Y.; Ma, D. J. Am. Chem. Soc. 2006, 128, 16050, and ref 2o.
4544 J. Org. Chem. Vol. 74, No. 12, 2009

CuI/4-Hydroxy-L-proline-Catalyzed Coupling of Bromides
TABLE 5. CuI/4-Hydroxy-L-proline-Catalyzed Coupling of Aryl
Bromides with Aqueous Ammoniaa
Experimental Section
General Procedure for the CuI/4-Hydroxy-L-proline-Catalyzed
Coupling Reaction of Aryl Bromides with N-Boc Hydrazide. A
mixture of aryl bromide (1 mmol), N-Boc hydrazine (2 mmol),
Cs2CO3 (2 mmol), CuI (0.1 mmol), and 4-hydroxy-L-proline (0.2
mmol) in 1 mL of DMSO was heated at 80 °C until the bromide
was consumed as indicated by TLC. The cooled mixture was
partitioned between water and ethyl acetate. The organic layer was
separated, and the aqueous layer was extracted with ethyl acetate.
The combined organic layers were washed with brine, dried over
Na2SO4, and concentrated in vacuo. The residual oil was loaded
on a silica gel column and eluted with 1:8 to 1:2 ethyl acetate/
petroleum ether to afford the corresponding N-aryl hydrazide.
tert-Butyl 1-(4-fluorophenyl)hydrazinecarboxylate (3f): pale
1
yellow oil; H NMR (300 MHz, CDCl3) δ 7.41-7.37 (m, 2H),
7.02-6.95 (m, 2H), 4.19 (br s, 2H), 1.48 (s, 9H); 13C NMR (100
MHz, CDCl3) δ 160.0 (d, J ) 242.4 Hz), 155.4, 139.4 (d, J ) 3.0
Hz), 125.5 (d, J ) 7.7 Hz, 2C), 115.0 (d, J ) 22.4 Hz, 2C), 82.1,
28.4 (3C); EI-MS m/z 226 (M+), 170, 153, 126, 110, 95, 83, 77,
57; EI-HRMS for C11H15FN2O2 (M+) requires 226.1118, found
226.1116.
tert-Butyl 1-(3-methylphenyl)hydrazinecarboxylate (3i): pale
1
yellow oil; H NMR (300 MHz, CDCl3) δ 7.27-7.15 (m, 3 H),
6.92 (d, J ) 6.9 Hz, 1H), 4.45 (br s, 2H), 2.30 (s, 3H), 1.47 (s,
9H); 13C NMR (100 MHz, CDCl3) 155.4, 143.3, 138.1, 128.2, 125.7,
124.4, 120.9, 81.8, 28.4 (3C), 21.7; EI-MS m/z 222 (M+), 166,
149, 133, 122, 106, 91, 77, 65, 57; EI-HRMS for C12H18N2O2 (M+)
requires 222.1368, found 222.1367.
General Procedure for the CuI-Catalyzed Coupling Reaction
of Aryl Iodides with N-Boc Hydrazide. A mixture of aryl iodide
(1 mmol), N-Boc hydrazine (1.2 mmol), Cs2CO3 (1.5 mmol), and
CuI (0.05 mmol) in 1 mL of DMSO was heated at 50 °C until the
iodide disappeared monitored by TLC. The cooled mixture was
partitioned between water and ethyl acetate. The organic layer was
separated, and the aqueous layer was extracted with ethyl acetate.
The combined organic layers were washed with brine, dried over
Na2SO4, and concentrated in vacuo. The residue was purified via
chromatography (eluting with 1:8 to 1:2 ethyl acetate/petroleum
ether) to afford the corresponding N-aryl hydrazide.
tert-Butyl 1-(3-fluorophenyl)hydrazinecarboxylate (3m): pale
1
yellow oil; H NMR (300 MHz, CDCl3) δ 7.34-7.19 (m, 3H),
6.81-6.75 (m, 1H), 4.42 (br s, 2H), 1.52 (s, 9H); 13C NMR (100
MHz, CDCl3) δ 162.7 (d, J ) 242.4 Hz), 154.9, 144.9 (d, J )
10.5 Hz), 129.2 (d, J ) 8.9 Hz), 118.4 (d, J ) 3.2 Hz), 111.1 (d,
J ) 20.9 Hz), 110.3 (d, J ) 28.6 Hz), 82.6, 28.4 (3C); EI-MS m/z
226 (M+), 170, 153, 137, 126, 111, 95, 83, 75, 57; EI-HRMS for
C11H15FN2O2 (M+) requires 226.1118, found 226.1116.
a Reaction conditions: aryl bromide (1 mmol), aqueous ammonia
(28%, 1 mL), CuI (0.2 mmol), 4-hydroxy-L-proline (0.4 mmol), K2CO3
(3 mmol), DMSO (2 mL), 50 °C, 24 h. b Reaction was carried out at 70
°C. c Reaction was carried out for 36 h.
tert-Butyl 1-(3-nitrophenyl)hydrazinecarboxylate (3v): yellow
present catalytic system is inexpensive and could be easily
removed by simple washing with water, our results may find
applications in the synthesis of related N-aryl compounds.9,10
1
oil; H NMR (300 MHz, CDCl3) δ 8.50 (s, 1 H), 7.98-7.89 (m,
2H), 7.44 (t, J ) 8.1 Hz, 1H), 4.49 (br s, 2H), 1.55 (s, 9H); 13C
NMR (100 MHz, CDCl3) δ 154.6, 148.3, 144.5, 128.9, 128.1, 118.7,
117.5, 83.4, 28.5 (3C); EI-MS m/z 253 (M+), 180, 166, 153, 136,
123, 105, 90, 77, 63, 57; EI-HRMS for C11H15N3O4 (M+) requires
253.1063, found 253.1066.
(9) (a) Peters, M. V.; Goddard, R.; Hecht, S. J. Org. Chem. 2006, 71, 7846.
(b) Kang, H.-M.; Lim, Y.-K.; Shin, I.-J.; Kim, H.-Y.; Cho, C.-G. Org. Lett.
2006, 8, 2047. (c) Schmidt, A. M.; Eilbracht, P. Org. Biomol. Chem. 2005, 3,
2333. (d) Lim, Y.-K.; Cho, C.-G. Tetrahedron Lett. 2004, 45, 1857. (e) Reich,
M. F.; Fabio, P. F.; Lee, V. J.; Kuck, N. A.; Testa, R. T. J. Med. Chem. 1989,
32, 2474. For other examples about coupling of aryl halides with hydrazines,
see: (f) Chae, J.; Buchwald, S. L. J. Org. Chem. 2004, 69, 3336. (g) Vin˜a, D.;
Olmo, E.; Lo´pez-Pe´rez, J. L.; Feliciano, A. S. Org. Lett. 2007, 9, 525. (h)
Hasegawa, K.; Kimura, N.; Arai, S.; Nishida, A. J. Org. Chem. 2008, 73, 6363.
(10) For other studies on the preparation of primary arylamines via metal-
catalyzed coupling reactions, see: (a) Lang, F.; Zewge, D.; Houpis, I. N.; Volante,
R. P. Tetrahedron Lett. 2001, 42, 3251. (b) Shen, Q.; Hartwig, J. F. J. Am.
Chem. Soc. 2006, 128, 10028. (c) Surry, D. S.; Buchwald, S. L. J. Am. Chem.
Soc. 2007, 129, 10354. (d) Gao, X.; Fu, H.; Qiao, R.; Jiang, Y.; Zhao, Y. J.
Org. Chem. 2008, 73, 6864. (e) Tao, C.-Z.; Li, J.; Fu, Y.; Liu, L.; Guo, Q.-X.
Tetrahedron Lett. 2008, 49, 70. (f) Gaillard, S.; Elmkaddem, M. K.; Fischmeister,
C.; Thomas, C. M.; Renaud, J.-C. Tetrahedron Lett. 2008, 49, 3471.
General Procedure for CuI/4-Hydroxy-L-proline-Catalyzed
Coupling of Aryl Bromides with Ammonia. A mixture of aryl
bromide (1 mmol), ammonia (28%, 1 mL), CuI (38 mg, 0.2 mmol),
trans-4-hydroxy-L-proline (52.4 mg, 0.4 mmol), and K2CO3 (414
mg, 3 mmol) in 2 mL of DMSO was heated at 50 °C until the
bromide was consumed as monitored by TLC. The cooled mixture
was partitioned between water and ethyl acetate. The organic layer
was separated, and the aqueous layer was extracted with ethyl
acetate. The combined organic layers were washed with brine, dried
over Na2SO4, and concentrated in vacuo. The residue was purified
by chromatography on silicon gel to provide the corresponding
primary aryl amine.
J. Org. Chem. Vol. 74, No. 12, 2009 4545

Jiang et al.
Biphenyl-4-amine (6f): 1H NMR (300 MHz, CDCl3) δ 7.55 (d,
J ) 7.2 Hz, 2H), 7.43-7.37 (m, 4H), 7.29-7.24 (m, 1H), 6.78 (d,
J ) 8.4 Hz, 2H), 3.72 (br s, 2H); EI-MS m/z 169 (M+), 152, 141,
128.
Aknowledgement. The authors are grateful to the Chinese
Academy of Sciences and the National Natural Science Founda-
tion of China (grant nos. 20621062 and 20872156) for their
financial support.
4-Methoxy-2-methylaniline (6m): 1H NMR (300 MHz, CDCl3)
δ 6.67 (m, 1H), 6.62 (m, 2H), 3.74 (s, 3H), 3.20 (br s, 2H), 2.17
(s, 3H); 13C NMR (300 MHz, CDCl3) δ 152.6, 138.2, 124.0, 116.3,
116.0, 112.0, 55.6, 17.6; EI-MS m/z 137 (M+), 122, 94, 77.
Naphthalen-1-amine (6o): 1H NMR (300 MHz, CDCl3) δ
7.84-7.79 (m, 2H), 7.49-7.43 (m, 2H), 7.34-7.25 (m, 2H), 6.79
(dd, J ) 1.5, 6.6 Hz, 1H), 4.16 (br s, 2H). EI-MS m/z 143 (M+),
140, 126, 115.
Supporting Information Available: The analytical data and
copies of 1H NMR and 13C NMR spectra for coupling products.
This material is available free of charge via the Internet at
http://pubs.acs.org.
JO9006738
4546 J. Org. Chem. Vol. 74, No. 12, 2009