Copper(II)-mediated oxidative coupling of 2-aminonaphthalene homologues. Competition between the straight dimerization and the formation of carbazoles

Article abstract of DOI:10.1021/jo005691w

Whereas the Cu(II)-mediated oxidative coupling of 2-aminonaphthalenes 7a and 7b results in the clean formation of 1,1′-binaphthyls 13a and 13b, respectively, their higher homologues and congeners 8 - 12 have been found to exhibit a different reaction pattern. Thus, 2-aminoanthracene (8) gave a ～1:1 mixture of the expected bianthryl derivative 15 and the carbazole 16, whereas the 9-aminophenanthrene (10), 3-phenyl-1-aminonaphthalene (11), and 2-aminochrysene (12) produced almost exclusively the corresponding carbazoles 19, 20, and 21, respectively. By contrast, the isomeric 3-aminophenanthrene (9) gave rise to the azo compound 17 as a result of the preferential oxidation on the nitrogen. The carbazoles have been shown to arise directly from the coupling reactions rather than from the primarily formed binaphthyls. Alternatively, carbazole 19 can also be prepared from 1b on reaction with hydrazine. On the other hand, treatment of 3a with hydrazine resulted in the formation of a ～2:7 mixture of amine 11 and arylhydrazine 22. 2,2′-Diamino-1,1′-bianthryl (15) has been resolved into enantiomers via Cocrystallization with (-)-N-benzylcinchonidinium chloride and shown to have (R)-(-)-15 configuration by X-ray crystallography.

Full text of DOI:10.1021/jo005691w

J . Org. Chem. 2001, 66, 1359-1365
1359
Cop p er (II)-Med ia ted Oxid a tive Cou p lin g of 2-Am in on a p h th a len e
Hom ologu es. Com p etition betw een th e Str a igh t Dim er iza tion a n d
th e F or m a tion of Ca r ba zoles)
Sˇteˇpa´n Vyskocˇil,*,†,‡ Martin Smrcˇina,X,§ Miroslav Lorenc,X Iva Tisˇlerova´,X Robin D. Brooks,|
J anusz J . Kulagowski, Vratislav Langer,∇ Louis J . Farrugia,† and Pavel Kocˇovsky´*,†,|,4
Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K., Department of Organic
Chemistry, Charles University, Hlavova 2030, 128 40 Prague 2, Czech Republic, Department of
Chemistry, University of Leicester, Leicester, LE1 7RH, U.K., Neuroscience Research Centre, Merck Sharp
& Dohme, Terlings Park, Harlow CM20 2QR, U.K., and Department of Inorganic Environmental
Chemistry, Chalmers University of Technology, 41296 Go¨teborg, Sweden
P.Kocovsky@chem.gla.ac.uk
Received October 20, 2000
Whereas the Cu(II)-mediated oxidative coupling of 2-aminonaphthalenes 7a and 7b results in the
clean formation of 1,1′-binaphthyls 13a and 13b, respectively, their higher homologues and
congeners 8-12 have been found to exhibit a different reaction pattern. Thus, 2-aminoanthracene
(8) gave a ∼1:1 mixture of the expected bianthryl derivative 15 and the carbazole 16, whereas the
9-aminophenanthrene (10), 3-phenyl-1-aminonaphthalene (11), and 2-aminochrysene (12) produced
almost exclusively the corresponding carbazoles 19, 20, and 21, respectively. By contrast, the
isomeric 3-aminophenanthrene (9) gave rise to the azo compound 17 as a result of the preferential
oxidation on the nitrogen. The carbazoles have been shown to arise directly from the coupling
reactions rather than from the primarily formed binaphthyls. Alternatively, carbazole 19 can also
be prepared from 1b on reaction with hydrazine. On the other hand, treatment of 3a with hydrazine
resulted in the formation of a ∼2:7 mixture of amine 11 and arylhydrazine 22. 2,2′-Diamino-1,1′-
bianthryl (15) has been resolved into enantiomers via cocrystallization with (-)-N-benzylcin-
chonidinium chloride and shown to have (R)-(-)-15 configuration by X-ray crystallography.
In tr od u ction
thyl (13a )1 have been shown to exhibit good to excellent
enantioselectivities in a number of asymmetric reactions.
Thus, for example, diamine 13a and its derivatives have
been employed as ligands for the enantioselective reduc-
tion of ketones,6a hydrogenation of R-acylaminoacrylic
acids,6b and other transformations.1,6c-i
Both the symmetrically and nonsymmetrically 2,2′-
disubstituted-1,1′-binaphthyls are widely used as chiral
ligands in asymmetric synthesis.1 In particular, BINOL,1
BINAP,1 MOP,2 NOBIN,3-5 and 2,2′-diamino-1,1′-binaph-
The classical approach to the binaphthyl skeleton
(Scheme 1) largely relies on the oxidative coupling of
2-naphthol (1a ) to give BINOL (4a ). A number of mild
oxidants have been reported to facilitate this reaction,
in particular, Cu(II), Fe(III), and Mn(III) salts.3,7 Other
methods involve melting the reactant8 or its ball-milling
in the presence of FeCl3‚6H2O.9 Oxidative coupling of
* Corresponding author.
) Dedicated to Dr. Zˇelim´ır Procha´zka on the occasion of his 80th
birthday.
† University of Glasgow.
‡ On leave from Charles University, Prague. E-mail: stepanv@natur.
cuni.cz.
X Charles University.
§ Current address: Aventis, 1580 East Hanley Blvd., Tucson, AZ
85737.
| University of Leicester.
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Merck Sharp & Dohme.
∇ Chalmers University of Technology.
4 Current address: University of Glasgow.
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(1) For recent reviews on binaphthyls, see: (a) Rosini, C.; Franzini,
L.; Raffaelli, A.; Salvadori, P. Synthesis 1992, 503. (b) Putala, M.
Enantiomer 1999, 4, 243. See also: (c) Noyori, R. Asymmetric Catalysis
in Organic Synthesis; Wiley & Sons: New York, 1994. (d) Ojima, I.
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(3) Smrcˇina, M.; Lorenc, M.; Hanusˇ, V.; Kocˇovsky´, P. Synlett 1991,
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Sˇ.; Kocˇovsky´, P. J . Org. Chem. 1993, 58, 4543. (d) Smrcˇina, M.;
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H.; Harper, K.; Claxton, T. A.; Kocˇovsky´, P. J . Am. Chem. Soc. 1996,
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dron: Asymmetry 1997, 8, 537. (g) Vyskocˇil, Sˇ.; Smrcˇina, M.; Kocˇovsky´,
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Commun. 1998, 585.
10.1021/jo005691w CCC: $20.00 © 2001 American Chemical Society
Published on Web 01/31/2001

1360 J . Org. Chem., Vol. 66, No. 4, 2001
Vyskocˇil et al.
Sch em e 1
Ch a r t 1
Sch em e 2
2-naphthol homologues has also been reported, such as
that of 9-phenanthrol (1b), furnishing 10,10′-dihydroxy-
9,9′-biphenanthryl (4b ),3c,10 and the dimerization of
3-phenanthrol (2), producing 4,4′-dihydroxy-3,3′-biphenan-
thryl (5).11,12 The synthesis of “vaulted” biaryls 6a and
6b has been effected by melting the corresponding
phenolic derivatives 3a and 3b, respectively.8 In all these
cases, the chiral axis was constructed in the position
vicinal to the hydroxyl group (marked by bold arrow in
Scheme 1). Herein, we report on the analogous coupling
of arylamines 8-12 (Chart 1) and demonstrate the wider
Ta ble 1. Cop p er (II)-Med ia ted Oxid a tive Cou p lin g of
Am in es 7-12
entry substrate diamine (%)a carbazole (%)a other (%)a
(7) Cu (II): (a) Ferringa, B.; Wynberg, H. Tetrahedron Lett. 1977,
4447. (b) Ferringa, B.; Wynberg, H. Bioorg. Chem. 1978, 7, 397. (c)
Kushioka, K. J . Org. Chem. 1983, 48, 4948. (d) Yamamoto, K.;
Fukushima, H.; Nakazaki, M. J . Chem. Soc., Chem. Commun. 1984,
1490. (e) Brussee, J .; Groenendijk, J . L. G.; te Koppele, J . M. J ansen,
A. C. A. Tetrahedron 1985, 41, 3313. (f) Sakamoto, T.; Yonehara, H.;
Pac, C. J . Org. Chem. 1994, 59, 6859. Cu (II)/O2: (g) Noji, M.;
Nakajima, M.; Koga, K. Tetrahedron Lett. 1994, 35, 7983. (h) Nakajima,
M.; Miyoshi, I.; Kanayama, K.; Hashimoto, S.; Noji, M.; Koga, K. J .
Org. Chem. 1999, 64, 2264. (i) Lipshutz, B. H.; J ames, B.; Vance, S.;
Carrico, I. Tetrahedron Lett. 1997, 38, 753. F e(III): ref 3h and the
following: (j) Pummerer, R.; Rieche, A. Chem. Ber. 1926, 59. (k) Toda,
F.; Tanaka, K.; Iwata, S. J . Org. Chem. 1989, 54, 3007 and references
therein. (l) Ding, K.; Wang, Y.; Zhang, L.; Wu, Y.; Matsuura, Y.
Tetrahedron 1996, 52, 1005. (m) Ding, K.; Xu, Q.; Wang, Y.; Liu, J .;
Yu, Z.; Du, B.; Wu, Y.; Koshima, H.; Matsuura, T. Chem. Commun.
1997, 693. Mn (III): (n) Dewar, M. J . S.; Nakaya, T. J . Am. Chem.
Soc. 1968, 90, 7134. (o) Yamamoto, K.; Fukushima, H.; Okamoto, Y.;
Hatada, K.; Nakazaki, M. J . Chem. Soc., Chem. Commun. 1984, 1111.
(p) Diederich, F.; Hester, M. R.; Uyeki, M. Angew. Chem., Int. Ed. Engl.
1988, 27, 1705.
1
2
3
4
5
6
7
8
7a
7b
7c
8
13a (58)b
13b (45)b
13c (26)b
15 (43)
-
14a (∼1)c
14b (3)
14c (21)
16 (39)
-
-
-
-
-
9
17 (87)
10
11
12
18 (2)
-
19 (78)d
20 (25)
21 (85)
-
-
-
-
a
d
Isolated by chromatography. b See ref 13. c GC yield. Starting
material was recovered (10%).
variability of the reaction course that contrasts with the
uniform behavior of their phenolic counterparts.
Resu lts a n d Discu ssion
Cou p lin g of Am in on a p h th a len es. By analogy to the
naphthols, arylamines 7-12 can also be anticipated to
undergo a preferential coupling in the electron-rich13
position marked by a bold arrow (Chart 1). Indeed, we
have recently reported on the Cu(II)-mediated oxidative
coupling reactions of 2-aminonaphthalenes 7a -c to
produce, as predicted, the binaphthyls 13a -c (Scheme
2) in good yields (Table 1, entries 1-3).3,13 While 7c gave
a substantial amount of the corresponding carbazole 14c
as a byproduct (entry 3), 7a and 7b reacted more
selectively, with only minute amounts of the carbazoles
14a and 14b detected (entries 1 and 2).3,13
(8) Bao, J .; Wulff, W. D. J . Am. Chem. Soc. 1993, 115, 3814. (b) Bao,
J .; Wulff, W. D.; Dominy, J . B.; Fumo, M. J .; Grant, E. B.; Rob, A. C.;
Whitcomb, M. C.; Yeung, S. M.; Ostrander, R. L.; Rheingold, A. L. J .
Am. Chem. Soc. 1996, 118, 3392. (c) Antilla, J . C.; Wulff, W. D. J . Am.
Chem. Soc. 1999, 121, 5099. (d) Antilla, J . C.; Wulff, W. D. Angew.
Chem., Int. Ed. 2000, 39, 4581.
(9) Rasmussen, M. O.; Axelson, O.; Tanner, D. Synth. Commun.
1997, 27, 4027.
(10) Yamamoto, K.; Fukushima, H.; Okamoto Y.; Hatada K.; Na-
kazaki M. J . Chem. Soc., Chem. Commun. 1984, 1111. (b) Yamamoto,
K.; Fukushima, H.; Nakazaki, M. J . Chem. Soc., Chem. Commun. 1984,
1490.
(11) Yamamoto, K.; Noda, K.; Okamoto, Y. J . Chem. Soc., Chem.
Commun. 1985, 1065.
(12) Interestingly, the originally proposed configuration for 511 has
been corrected to (R)-(-): (a) Koike, N.; Hatori, T.; Miyano, S.
Tetrahedron: Asymmetry 1994, 5, 1899. (b) Hayashi, T.; Iwamura, H.;
Uozumi, M.; Matsumoto, Y.; Ozawa, T. Synthesis 1994, 526. (c) Dore,
A.; Fabbri, D.; Gladiali, S. Tetrahedron: Asymmetry 1995, 6, 779.
(13) Smrcˇina, M.; Vyskocˇil Sˇ.; Ma´ca, B.; Pola´sˇek, M.; Claxton, T.
A.; Abbott, A. P.; Kocˇovsky´, P. J . Org. Chem. 1994, 59, 2156.

Oxidative Coupling of 2-Aminonaphthalene Homologues
J . Org. Chem., Vol. 66, No. 4, 2001 1361
Sch em e 3
Cou p lin g of Am in on a p h th a len e Hom ologu es. Al-
though the coupling procedures developed for 2-amino-
naphthalenes 7 were successful,3,13 analogous processes
have not been studied for homologous aromatic amines.
To explore the scope of this methodology, we set out to
investigate the coupling reactions of arylamines 8-12
using a complex of CuCl2 and benzylamine, which proved
to be the reagent of choice in our previous studies.3 While
the ultimate environment of the candidate positions for
coupling in 8, 10, and 12 resembles that of 7a (Chart 1),
more steric hindrance can be anticipated for 11 and, in
particular, for 9. Differences can also be identified in the
steric hindrance of individual amino groups. Thus, in 8,
9, and 12, the NH2 seems to be as free as that in 7a ,
whereas in the case of 7c, 10, and 11 it is hindered by
neighboring groups (the ester functionality and the peri-
substituents, respectively). Although the corresponding
hydroxy derivatives 1 and 2 exhibited little influence of
the steric congestion on the efficiency of the coupling
reactions, we envisaged that the same picture may not
necessarily be obtained with the amines.
The reaction of 2-aminoanthracene (8) with CuCl2-
PhCH2NH2 (MeOH, rt, 24 h; Scheme 2) afforded a
mixture of diamine 15 (43%)14 and carbazole 16 (39%,
entry 4),15 a result similar to that obtained for 7c (entry
3).13 The couplings of 9-aminophenanthrene (10), 3-phen-
yl-1-aminonaphthalene (11),16 and 2-aminochrysene (12)
turned out to give mainly the carbazoles 19,17 20, and
21 (Scheme 3), respectively (entries 6-8); the corre-
sponding diamines were either formed in minute quanti-
ties (2% of 18;18 entry 6), or not at all (entries 7 and 8).
The structure of carbazole 20 has been confirmed by
single-crystal X-ray crystallography. In contrast to these
reactions, the attempted self-coupling of 3-aminophenan-
threne (9) gave the azo compound 1719 as the main
product (entry 5).
Apparently, increasing the steric hindrance around the
amino group is detrimental to the formation of the
diamines but not to the biaryl coupling itself: while 7a
and 7b give the corresponding diamines 13a and 13b in
high yields, a ∼1:1 mixture of the diamine and the
carbazole is formed in the case of 7c, and a practically
exclusive formation of the carbazole was found for 10 and
11. However, electronic factors must also play a role,
since 8, having a similar steric environment to that in
7a , afforded a ∼1:1 mixture, and the chrysene homologue
12 produced the carbazole exclusively. Steric hindrance
at the expected coupling position, as in 9 or 11, led to a
low yield of the expected carbazole (15% yield in 11 f
20), or even precluded the coupling and, instead, pro-
moted oxidation on the nitrogen (9 f 17).
The actual mechanism for the formation of the carba-
zoles is not clear. Control experiments revealed that the
diamines (e.g., 13c or 15) are inert to prolonged treat-
ment (24 h) under the conditions of the coupling reaction.
Hence, the carbazoles must arise directly from the
starting amines in a competing reaction rather than via
a secondary transformation of the diamines.20
(14) The preparation of 15 has also been reported from the corre-
sponding 2,2′-dicarboxylic acid via the Curtius rearrangement: (a)
Lauer, K.; Oda, R.; Miyawaki, M. J . Prakt. Chem. 1937, 148, 310. (b)
Bell F.; Waring D. H. J . Chem. Soc. 1949, 1579. For the chiroptical
properties of this material, and a tentative assignment of absolute
configuration for 15, see: (c) Fitts, D. D.; Siegel, M.; Mislow, K. J . Am.
Chem. Soc. 1958, 80, 480. (d) Our synthetic procedure resulted in the
formation of a compound that has a distinctly different mp and
somewhat lower [R]D compared to the literature data14a,b (see the
Experimental Section for details). Furthermore, one report14b described
the alleged 15 as “white crystals” whereas according to the other
report14a it formed a “red-yellow solution in benzene or chloroform with
green fluorescence”. The latter description is certainly closer to our
own observation (a yellow material). The single-crystal X-ray analysis
(vide infra) proved the structure 15 for our product and also established
the absolute configuration (both from the Flack factor and through
the relation to the cinchonidine derivative in the crystal); chiral HPLC
demonstrated its enantiopurity. We have no explanation for the
discrepancy in data except that, perhaps, the other authors mixed up
the appearance of the free amine with that of its hydrochloride and
the melting point for the enantiomerically pure compound with that
of the racemate.
(15) For an alternative preparation of carbazole 16, see: (a) Zander,
M.; Franke, W. H. Chem. Ber. 1966, 99, 2449. (b) Brandt, J .; Fauth,
G.; Franke, W. H.; Zander, M. Chem. Ber. 1971, 104, 519.
(16) Prepared from 3a 8 via Bucherer reaction in 56% yield: Selvaraj,
S.; Ramakrishnan, P. S.; Arumugam, N. Recl. Trav. Chim. Pays-Bas
1989, 108, 36.
(19) (a) This reaction involves two oxidation steps (the C-C coupling
itself and the N-N bond oxidation). The standard procedure using 1
equiv of Cu(II) lead to an inseparable mixture of 17 and the corre-
sponding hydrazo derivative, as revealed by GCMS. Therefore, to run
the reaction to completion, 2 equiv of CuCl2 were employed. (b) The
azo derivative 17 is assumed to be a trans-isomer in view of the
generally higher stability of trans-azo compounds. Thus, for instance,
cis-azo-2,2′-naphthalene has been reported to isomerize to the trans-
isomer with τ1/2 ) 150 min at 29 °C: Frankel, M.; Wolovsky, R.; Fischer,
E. J . Chem. Soc. 1955, 3441.
(17) Carbazole 19 has been prepared previously by the iodine-
mediated oxidation of 10 at 260 °C or by photolysis of the aziridine
derived from phenanthrene: Weitzberg M.; Avnir D.; Aizenshtat Z.;
Blum J . J . Heterocycl. Chem. 1983, 20, 1019.
(18) Diamine 18 also has been synthesized by the Zn-KOH reduc-
tion of the corresponding dinitro derivative, which, in turn, was
obtained via the Cu-mediated dimerization of 9-nitro-10-bromophenan-
threne: Hughes, A. N.; Prankprakma, V. Tetrahedron 1966, 22, 2053.

1362 J . Org. Chem., Vol. 66, No. 4, 2001
Vyskocˇil et al.
Sch em e 4
Sch em e 5a
Since the preparation of the diamines from 10 and 11
failed, another approach was attempted, based on the
analogy with 2-naphthol (1a ), which can be readily
converted into the diamine 13a on heating with hydra-
zine hydrate in an autoclave.21,22 However, under the
same conditions (190 °C, 48 h), 1b afforded, again, the
carbazole 19 (58%) rather than the expected diamine.
This experiment shows that the carbazole formation is
not associated with the presence of the oxidizing agent
but, rather, with the nature of the skeleton. Interestingly,
3a produced, under the same conditions (Scheme 4), a
mixture of amine 11 (9%), identical with the compound
prepared from 3a via Bucherer reaction,16 and hydrazine
derivative 22 (30%).
Comparison of the reactivity of the phenolic substrates
1-3 with that of the amines 7-12 shows that there must
be a fundamental difference in the mechanism of the
dimerization. Whereas 1-3 readily afford the corre-
sponding diols (Scheme 1), the amines exhibit greater
variability, affording diamines, carbazoles, or even the
product of N,N-dimerization (Schemes 2 and 3). We
believe that the mechanistic rationale can be found in
the oxidation of 9, which differs most dramatically from
the coupling of its oxygen analogue 2. An exclusive
formation of the azo derivative 17 on the oxidation of 9
suggests that the oxidative N,N-dimerization represents
a competing pathway for the amines. Under normal
circumstances, the C-C coupling prevails but if the
candidate position is more hindered (as in 9), the
alternative reaction becomes relatively less costly in
energy and the azo derivative 17 is formed, presumably
via the corresponding hydrazo intermediate.19a,23 Note
that this pathway is not available for the phenolic
derivatives (e.g., 2), as it would generate an unstable
peroxide intermediate. Hence, assuming the two compet-
ing pathways a and b (Scheme 5) for the Cu(II)-facilitated
reaction of amines, exemplified by 7, path a would lead
directly to the diamine 13, whereas path b would gener-
ate the hydrazo species 23, which is also believed to be
the intermediate in the reaction of, e.g., 2-naphthol (1a )
with hydrazine.21,22,24 Rearrangement of 23 would then
generate 24, which can either be stabilized by tautomer-
ization to produce diamine 13 (path c) or undergo an
intramolecular attack on one of the imino groups (path
d); elimination of ammonia from the intermediate 25 thus
a
X ) H or CO2Me.
formed would then give rise to the carbazole 14. The
latter mechanism is further supported by the reaction of
1b with hydrazine, which gives carbazole 19 (vide supra),
showing that for the carbazole formation from 23, Cu-
(II) is not required. The competition between pathways
c and d is apparently influenced by steric and electronic
factors; control experiments have demonstrated that path
c is irreversible under the reaction conditions.20,25 The
sterically congested hydrazo intermediate (analogous to
23), arising from 9, is further oxidized to produce 17 in
preference to the C-C bond-forming rearrangement.
Resolu tion a n d Absolu te Con figu r a tion of 2,2′-
Dia m in o-1,1′-bia n th r yl (15). Diamine (()-15 was re-
solved via the method developed by Toda26 and further
improved by the Merck group27 for the resolution of
BINOL:27,28 Racemic 15 was cocrystallized with (-)-N-
benzylcinchonidinium chloride (-)-26 from acetonitrile
to produce a 1:1 inclusion complex (or molecular crystal28)
(25) Note that while 2-naphthol readily reacts with hydrazine,
BINOL is inert, which demonstrates that the keto form is not available
in the latter case. Similarly, generating the imino form 23 from amine
13 can be regarded as unlikely, lending further credence to our
mechanistic argument.
(26) Tanaka, K.; Okada, T.; Toda, F. Angew. Chem., Int. Ed. Engl.
1993, 32, 1147. (b) Toda, F.; Tanaka, K.; Stein, Z.; Goldberg, I. J . Org.
Chem. 1994, 59, 5748.
(27) The original Toda’s method suffered from lower enantioselec-
tivity. A simple switching of the solvent employed for crystallization
from methanol to acetonitrile dramatically improved the resolution of
BINOL: (a) Cai, D.; Hughes, D. L.; Verhoeven. T. R.; Reider, P. J .
Tetrahedron Lett. 1995, 36, 7991. For other recent applications of this
method, see: (b) Reeder, J .; Castro, P. P.; Knobler, C. B.; Martinbor-
ough, E.; Owens, L.; Diederich, F. J . Org. Chem. 1994, 59, 3151. (c)
Wipf, P.; J ung, J .-K. J . Org. Chem. 2000, 65, 6319. (d) Wang, Y.; Sun,
J .; Ding, K. L. Tetrahedron 2000, 56, 4447.
(28) This method has recently been applied to the resolution of
NOBIN with acetone as the preferred solvent: Ding, K.; Wang, Y.;
Yun, H.; Liu, J .; Wu, Y.; Terada, M.; Okubo, Y.; Mikami, K. Chem.
Eur. J . 1999, 5, 1734.
(20) On the other hand, pyrolysis of the hydrochloride of 13a or
refluxing 13a in 2 N H2SO4 are known to produce carbazole 14a ,
apparently owing to the conversion of the NH2 into a good leaving
group by protonation: (a) Meisenheimer, J .; Witte, K. Chem. Ber. 1903,
36, 4153. (b) Banthorpe, D. V. J . Chem. Soc. 1962, 2407 and 2413. (c)
Bridger, R. F.; Law, D. A.; Bowman, D. F.; Middleton, B. S.; Ingold, K.
U. J . Org. Chem. 1968, 33, 4329.
(21) Miyano, S.; Nawa, M.; Mori, A.; Hashimoto, H. Bull. Chem. Soc.
J pn. 1984, 57, 2171.
(22) Shine, H. J .; Gruszecka, E.; Subotkowski, W.; Brownawell, M.;
San Filippo, J ., J r. J . Am. Chem. Soc. 1985, 107, 3218.
(23) Traces of the corresponding hydrazo compound could be de-
tected by EI MS (direct inlet) analysis of the reaction mixture.
(24) Shine, H. J .; Trisler, J . C. J . Am. Chem. Soc. 1960, 82, 4054.
(b) Shine, H. J .; Huang, F.-T.; Snell, R. L. J . Org. Chem. 1961, 26,
380. (c) Banthorpe, D. V.; Hughes, E. D.; Ingold, C. J . Chem. Soc. 1962,
2418 and refs cited therein.

Oxidative Coupling of 2-Aminonaphthalene Homologues
J . Org. Chem., Vol. 66, No. 4, 2001 1363
Ch a r t 2
that was diastereoisomerically enriched by 73% (de) as
shown by chiral HPLC (Chart 2). A single crystallization
of the latter complex from a dichloromethane-diethyl
ether mixture furnished a diastereoisomerically pure
species (i.e., 15 of ∼100% ee). This material was char-
acterized by single-crystal X-ray crystallography (Figure
1) that revealed not only the (R)-configuration of 15 but
also an interesting fit of the molecule of (R)-15 into the
cleft created by the quinoline nucleus and the vinyl group
of the alkaloid on one side and the insertion of the benzyl
group of (-)-26 into the cleft of another molecule of (R)-
15.29 Another interesting structural feature is the forma-
tion of an infinite 3D-network of hydrogen bonds with
the chloride ion as their acceptor; both amino groups of
15 and the hydroxy group of 25 are involved. Together
with three other contacts (C3A of 15 and C8C and C11C
of 26), a distorted square bipyramid of hydrogen contacts
around the Cl- ion is thus formed.
F igu r e 1. ORTEP diagram of the inclusion complex (R)-(-)-
15‚(-)-26 showing the atom labeling scheme. Displacement
parameters are shown at the 30% probability level. H atoms
are omitted for clarity and their positions are indicated by thin
lines.
solutions at 25 °C. 2D NMR techniques (COSY, HSQC, and
HMBC) and DEPT were used for signal assignment. The IR
spectra were measured in chloroform. The high-resolution
mass spectra were measured on a double focusing spectrometer
(70 eV, 3 kV) using a direct inlet and the lowest temperature
enabling evaporation; the accuracy was e5 ppm. All the
solvents used for the reactions or for crystallization experi-
ments were degassed by purging with argon (20 min; 60 mL
Ar/min). Petroleum ether refers to the fraction boiling in the
range 40-60 °C. Yields are given in milligrams of isolated
product showing one spot on a chromatographic plate and no
impurities detectable in the NMR spectra. Crystal data for
carbazole 20: C32H21N, M ) 419.52. Crystals (pale yellow) were
obtained from a CH2Cl2 solution into which hexane slowly
diffused at ∼0 °C over a period of 2 weeks; they are orthor-
hombic of space group Pcab, a ) 13.6545(3) Å, b ) 15.2033(3)
Å, c ) 20.1647(5) Å. Data were collected at 150 K on a Nonius
KappaCCD diffractometer, running under Nonius-Collect
software, and using graphite monochromated X-radiation (λ
) 0.71073 Å). Precise unit cell dimensions were determined
by refinement of the setting angles of 5221 reflections. Lorentz-
polarization corrections were then applied to the reflection
data. The data were averaged using SORTAV and an empirical
absorption correction was applied.32 The structure was solved
by direct methods (SHELXS-9733). All non-H atoms were
allowed anisotropic thermal motion. Aromatic C-H hydrogen
atoms were included at calculated positions, with C-H ) 0.96
Å, and were refined with a riding model and with Uiso set to
1.2 times that of the attached C-atom. The H atom of nitrogen
was found from a difference map and was refined without
constraints. Refinement (SHELXL97-233) was performed by
full-matrix least-squares on F2, using all the unique data and
the weighting scheme w ) [σ2(Fo)2 +(AP)2 + BP]-1 where P )
[Fo2/3 + 2Fc2/3] and A ) 0.0644 B ) 0.0. Neutral atom
scattering factors, coefficients of anomalous dispersion, and
absorption coefficients were obtained from ref 34. Calculations
using PLATON35 indicated that there were no voids in the
lattice capable of containing any solvent molecules. Thermal
ellipsoid plots were obtained using the program ORTEP-3 for
Windows.36 All calculations were carried out using the WinGX
package37 of crystallographic programs. The estimated error
in the bond distances is 0.002 Å. Crystal data for the molecular
crystal (R)-(-)-15‚(-)-26: C27H29ClN4O, M ) 805.44. Crystals
Dissolving the crystal in dichloromethane, followed by
a chromatographic separation of the desired product from
benzylcinchonidinium chloride, afforded a laevorotatory
material. Therefore, 2,2′-diamino-1,1′-bianthryl can be
assigned the (R)-(-)-15 configuration.30
Con clu sion
We have prepared the bianthryl diamine (R)-(-)-15 as
a potential new ligand for asymmetric synthesis.31 Fur-
ther investigation has led to defining the scope of the
oxidative coupling of aromatic amines, in particular, of
the extent of the formation of carbazoles and other
byproducts. In the case of 10, 11, and 12, this protocol
can be used as a reliable synthetic route to the corre-
sponding carbazoles 19, 20, and 21. Two competing
mechanisms have been proposed for the coupling of
amines (Scheme 5), one leading directly to the C-C bond
formation (7 f 13), the other to the N-N coupling (7 f
23); the latter pathway can branch either to diamine (13),
carbazole (14), or azo-derivative (17) as the product.
Exp er im en ta l Section
Ma ter ia ls a n d Equ ip m en t. Optical rotations were mea-
sured with an error of < ( 0.1; the [R]D values are given in
1
10-1 deg cm2 g-1. H NMR spectra were recorded on a 400 or
250 MHz instrument (FT mode) for CDCl3 solutions at 25 °C
with TMS as internal reference. The 13C NMR spectra were
recorded at 101 MHz (FT mode) for CDCl3 or acetone-d6
(29) The importance of the vinyl group for the resolution process is
further demonstrated by our failure to resolve (()-15 with benzylcin-
choninium chloride, a diastereoisomer of benzylcinchonidinium chlo-
ride, where the vinyl group is not available in the right position.
(30) This assignment confirms that made tentatively by Mislow.14c
However, see the comments on the reported structure (ref 14d).
(31) The cost of 8 as starting material for 15 might be viewed as a
deterrent (5 g at £ 33.40 according to the latest Aldrich catalogue).
However, 8 can be readily prepared on a large scale in an economically
viable way by reduction of 2-aminoanthraquinone (500 g at £ 22.40)
with zinc in aqueous NaOH solution: Ruggli, P.; Henzi, E. Helv. Chim.
Acta 1930, 13, 409.
(32) Blessing, R. H. Acta Crystallogr. 1995, A51, 33.
(33) SHELX-97 Programs for crystal structure analysis: Sheldrick,
G. M. University of Go¨ttingen, Germany, 1997, Release 97-2.
(34) Tables 4.2.4.2, 4.2.6.8, 6.1.1.4 from International Tables for
Crystallography, Volume C Mathematical, Physical and Chemical
Tables; Kluwer: Dordrecht, 1995.
(35) PLATON: Spek, A. L. Acta Crystallogr. 1990, A46, C34.
(36) Farrugia, L. J . J . Appl. Crystallogr. 1997, 30, 565.
(37) Farrugia, L. J . J . Appl. Crystallogr. 1999, 32, 837.

1364 J . Org. Chem., Vol. 66, No. 4, 2001
Vyskocˇil et al.
were obtained by a slow crystallization from acetonitrile
solution; they are monoclinic, of space group P21, a ) 13.4647-
(6) Å, b ) 10.5784(4) Å, c ) 15.5742(6) Å, â ) 101.796(1). Data
were collected at -85 °C on a Siemens SMART CCD diffrac-
tometer using Mo KR radiation (λ ) 0.71073 Å), a graphite
monochromator, and ω scan mode at four different φ orienta-
tions, covering thus the entire reciprocal sphere up to 0.73 Å
resolution. A total of 28054 reflections were measured, from
which 11610 were unique (Rint ) 0.0388), with 8382 observed
data having I > 2σI. All reflections were used in the structure
refinement based on F2 by full-matrix least-squares technique
with hydrogen atoms calculated into theoretical positions,
riding during refinement on the respective pivot atom (592
parameters). Final R-factors: R1 ) 0.0455 for the observed
data and 0.0768 for all data; wR2 ) 0.0998, S ) 1.010. Flack
x parameter ) -0.0447 with esd 0.0432; expected values are
0 (within 3 esd’s) for the correct and +1 for inverted absolute
structure and thus there is no doubt about the absolute
structure determination. The estimated error in the bond
distances is in the interval 0.002 to 0.004 Å. All calculations
were performed using SHELXTL software [SHELXTL (version
5.10), Structure Determination Software Programs, Bruker
AXS Inc., Madison, WI, 1997].
Gen er a l P r oced u r e for th e Cou p lin g. A solution of
benzylamine (4.28 g; 40 mmol) in degassed methanol (50 mL)
was added to a stirred solution of CuCl2‚2H2O (1.7 g; 10 mmol)
in degassed methanol (150 mL). The solution was purged with
argon for 5 min, a solution of the arylamine (10 mmol) in
degassed anisole (50 mL) was added, and the mixture was
stirred at room temperature for 24 h under argon. The reaction
mixture was then first acidified with concd HCl (50 mL),
stirred for 5 min, and then treated with concd ammonia (100
mL) for another 5 min and finally diluted with water (1 L).
The resulting suspension was extracted with CHCl3 (3 × 100
mL), and the organic extract was dried with Na2SO4 and
evaporated.
in Et2O (10 mL) and evaporated under reduced pressure. The
residue was chromatographed on a column of silica gel (20 g)
with a 1:1 mixture of hexane and ethyl acetate to elute amine
11 (20 mg; 9%) followed by the hydrazine derivative 22 (70
mg, 30%). Amine 11 was identical with the product obtained
from the Bucherer reaction (method A).
Oxid a tive Cou p lin g of 8. The oxidative coupling was
carried out as described in the general procedure, using 8 (1.93
g). After workup, the residue was chromatographed on silica
(300 g) using toluene as eluent to give diamine 15 (820 mg,
43%) and carbazole 16 (710 mg, 39%).
2,2′-Dia m in o-1,1′-bia n th r yl (15): mp 160-3 °C (toluene),
165-8 °C (benzene-ethanol; lit.14b gives 233 °C for the
compound crystallized from benzene-ethanol);1H NMR (400
MHz, CDCl3) δ 3.76 (br s, 4 H, NH2), 7.19-7.31 (m, 6 H), 7.53
(dd, J ) 8.4 and 0.8 Hz, 2 H), 7.34 (s, 2 H), 7.92 (dd, J ) 8.2
and 0.8 Hz, 2 H), 8.06 (dd, J ) 9.6 and 0.8 Hz, 2 H), 8.40 (s,
2 H); 13C NMR δ 110.12 (s), 120.14 (d), 121.21 (d), 123.99 (d),
125.20 (d), 126.84 (d), 127.93 (d), 127.94 (d), 128.26 (s), 129.61
(s), 130.01 (d), 131.93 (s), 132.64 (s), 141.98 (s); IR (CHCl3) ν
3390 and 3486 (NH) cm-1; MS (EI) m/z (%) 384 ([M]+•, 100),
383 (14), 368 (24), 367 (C28H17N, 37), 192 (M2+, 8), 190 (8),
183.5 (13), 183 (11), 182.5 (17), 176 (10), 169.5 (14); HRMS
for C28H20N2 calcd 384.1626 found 384.1629.
Resolu tion of (()-15. A solution of racemic 15 (384 mg, 1
mmol) and (-)-N-benzylcinchonidinium chloride (210 mg, 0.5
mmol) in acetonitrile (5 mL) was heated at 70 °C for 4 h. The
mixture was then cooled, and the crystals formed were washed
with acetonitrile (1 mL) and isolated with suction to give the
inclusion complex (345 mg). Chiral chromatography on a Daicel
Chiralpak AD column with a 68:22:10 hexane-methanol-2-
propanol mixture as eluent (flow rate 1 mL/min, UV detection
at 256 nm) showed that the crystals contained (R)-15 enriched
in 73% ee (tR ) 8.6 min, tS ) 12.4 min). The crystals were then
dissolved in dichloromethane (1 mL), and the solution was
covered with a layer of diethyl ether (5 mL) and allowed to
slowly crystallize. The crystals (240 mg) thus formed contained
the enantiomerically pure (R)-(-)-15, as revealed by chiral
chromatography: mp 240-242 °C. Dissolving these crystals
in dichloromethane followed by chromatography on silica gel
with CH2Cl2 afforded pure (R)-(-)-15 (132 mg, 34%): mp
253-5 °C (benzene-ethanol; lit.14b gives 182-4 °C from the
same solvent or 174-5 °C from an unidentified solvent14a); [R]D
-302 (c 4, CHCl3) [lit. [R]D -384 (c 4, CHCl3)14b or -336.7
(CHCl3)14a]. The mother liquor from the first resolution step
was evaporated under a reduced pressure to give an amor-
phous material (240 mg) that contained (S)-(+)-15 enriched
in 72% ee.
3-P h en yl-1-a m in on a p h th a len e (11). Meth od A. A mix-
ture of 3a 8b,38 (855 mg; 3,87 mmol), NaHSO3 (5 g), 30% aqueous
ammonia (40 mL), and water (10 mL) was heated in a sealed
tube at 200 °C for 48 h. The mixture was then cooled, treated
with 10% aqueous KOH (40 mL), and extracted with ether.
Gaseous HCl was then passed through this ethereal solution,
and the solid hydrochloride was collected by filtration. The
hydrochloride was dissolved in water (50 mL), the solution was
alkalized with a 10% aqueous NaOH, and the free base was
extracted with ether. Evaporation of the ethereal solution
followed by crystallization from petroleum ether afforded solid
11 (358 mg; 42%), which decomposed at g100 °C before
melting; hydrochloride 11‚HCl had mp 124-6 °C (methanol-
8H-Din a p h th o[2,3-c:2′,3′-g]ca r ba zole (16): mp 274-7 °C
1
(toluene; lit.15 gives 264-6 °C); H NMR (400 MHz, CDCl3) δ
1
dichloromethane); H NMR (400 MHz, CDCl3) δ 4.26 (br s, 2
7.50-7.61 (m, 4 H), 7.70 (d, J ) 9.0 Hz, 2 H), 7.99 (d, J ) 9.0
Hz, 2 H), 8.10 (dd, J ) 9.2 Hz, J ) 0.9 Hz, 2 H), 8.18 (dd, J )
9.2 Hz, J ) 0.9 Hz, 2 H), 8.61 (s, 2 H), 8.94 (s, 1 H), 9.94 (s, 2
H); 13C NMR δ 114.01 (d), 117.24 (s), 122.95 (d), 124.79 (d),
125.75 (d), 127.01 (d), 127.46 (d), 127.80 (s), 127.92 (d), 128.06
(d), 129.83 (s), 130.06 (s), 131.28 (s), 134.69 (s); IR (CHCl3) ν
3462 (NH) cm-1; MS (EI) m/z (%) 367 ([M]+•, 100), 366(17),
364 (10), 183.5 (M2+, 9), 182.5 (9), 181.5 (10), 169.5 (10); HRMS
for C28H17N calcd 367.1361 found 367.1363.
H, NH2), 7.05 (d, J ) 1.7 Hz, 1 H, 2-H), 7.35 (tt, J ) 7.8 and
1.5 Hz, 1 H, 4′-H), 7.44 (m, 1 H, 7-H), 7.45 (m, 2 H, 3′-H and
5′-H), 7.47 (m, 1 H, 6-H), 7.52 (br s, 1 H, 4-H), 7.67-7.71 (m,
2 H, 2′-H and 6′-H), 7.82 (m, 1 H, 8-H), 7.84 (m, 1 H, 5-H); 13
C
NMR δ 109.19 (d, C-2), 117.06 (d, C-4), 120.67 (d, C-8), 122.88
(s, C-9), 124.84 (d, C-7), 126.23 (d, C-6), 127.19 (d, C-4′), 127.26
(2 × d, C-2′ and C-6′), 128.65 (2 × d, C-3′ and C-5′), 128.80 (d,
C-5), 134.63 (s, C-10), 139.09 (s, C-3), 141.36 (s, C-1′), 142.45
(s, C-1); IR (CHCl3) ν 3481 and 3397 (NH), 1626 and 1596 (Cd
C arom) cm-1; MS m/z (%) 219 ([M]+•, 100), 217 (9.8), 202 (2.5),
191 (6.3), 165 (3.3), 140 (2.2), 115 (2.6), 109 (5.5).
Meth od B. A mixture of 3-phenyl-1-naphthol 3a 8b,38 (220
mg, 1 mmol) and a 100% hydrazine hydrate (250 mg, 5 mmol)
was heated in a sealed tube at 200 °C for 24 h. The reaction
mixture was poured in water (10 mL) and extracted with Et2O
(3 × 10 mL). The organic phase was dried with anhydrous
MgSO4 and filtered. A solution of HCl in THF (2 mL of 1 M
solution) was then added, and the precipitate that contained
hydrochlorides of 11 and 22 was filtered off. The etheric phase,
containing mainly the unreacted naphthol 3a , was discarded.
The mixture of hydrochlorides was treated with satd ammonia
Oxid a tive Cou p lin g of 9. The oxidative coupling was
carried out as described in the general procedure, using 9 (1.93
g, 10 mmol) and a complex of copper(II) chloride dihydrate (3.4
g, 20 mmol) with benzylamine (5.56 g, 80 mmol); note that, in
this case, 2 equiv of Cu(II) were required (one for the coupling
and one for the N,N-oxidation). After workup, the residue was
chromatographed on a column of silica gel (200 g) using a
toluene-petroleum ether mixture (1:1) as eluent to give the
azo compound 17 (1.66 g, 87%).
1
Azo-3,3′-p h en a n th r en e (17): mp 266-9 °C (toluene); H
NMR (400 MHz, CDCl3) δ 7.68 (ddd, J ) 8.0 Hz, J ) 6.9 Hz,
J ) 1.2 Hz, 2 H), 7.77 (ddd, J ) 8.3 Hz, J ) 6.9 Hz, J ) 1.4
Hz, 2 H) 7.84 (bd, J ) 9.2 Hz, 2 H), 7.87 (bd, J ) 9.2 Hz, 2 H)
7.96 (dd, J ) 7.8 Hz, J ) 1.4 Hz, 2 H), 8.05 (d, J ) 8.6 Hz, 2
H), 8.29 (dd, J ) 8.5 Hz, J ) 1.8 Hz, 2 H), 8.91 (dm, J ) 8.2
Hz, 2 H), 9.40 (d, J ) 1.8 Hz, 2 H); 13C NMR δ 118.34 (d),
(38) Kipping, C.; Schiffer, H.; Scho¨nfelder, K. J . Prakt. Chem. 1973,
315, 887.

Oxidative Coupling of 2-Aminonaphthalene Homologues
J . Org. Chem., Vol. 66, No. 4, 2001 1365
121.80 (d), 123.06 (d), 126.57 (d), 127.10 (2 × d), 128.73 (d),
128.79 (d), 129.67 (d), 130.84 (s), 130.91(s), 132.30 (s), 133.93
(s), 151.01 (s); IR (CHCl3) ν 1612 and 1602 (CdC arom); MS
m/z (%) 382 ([M]+•, 32), 354 (5), 352 (7), 191 (4), 177 (100), 176
(18), 151 (9); HRMS for C28H18N2 calcd 382.1470 found
382.1476.
(d), 125.54 (d), 125.58 (d), 126.38 (d), 128.12 (2 × d), 128.37 (2
× d), 128.81 (d), 131.66 (s), 135.15 (s), 136.90 (s), 143.04 (s);
IR (CHCl3) ν 3488 (NH), 1600 (CdC arom) cm-1; MS (EI) m/z
(%) 419 ([M]+•, 100), 341 (16), 209.5 (M2+, 4), 170.5 (30); HRMS
for C32H21N calcd 419.1674 found 419.1672.
Oxid a tive Cou p lin g of 12. The oxidative coupling was
carried out as described in the general procedure, using 12
(2.43 g). After workup, the residue was chromatographed on
a column of silica gel (50 g) using toluene as eluent to give
carbazole 21 (2.06 g, 85%).
Oxid a tive Cou p lin g of 10. The oxidative coupling was
carried out as described in the general procedure, using 10
(1.93 g). After workup, the residue was chromatographed on
a column of silica gel (50 g) using toluene as eluent to give
carbazole 19 (1.43 g, 78%) and a mixture of unreacted 10 and
diamine 18. The latter mixture was separated using a semi-
preparative HPLC (Magnum 9 column, Whatman) with a
petroleum ether-ethyl acetate mixture (4:1) as eluent to give
diamine 18 (40 mg, 2%) and unreacted 10 (190 mg, 10%).
10,10′-Dia m in o-9,9′-bip h en a n th r yl (18):18 1H NMR (400
MHz, CDCl3) δ 4.17 (bs, 4 H), 7.20 (dd, J ) 8.2 Hz, J ) 1.2
Hz, 2 H), 7.26-7.31 (m, 2 H), 7.42-7.47 (m, 2 H), 7.68-7.80
(m, 4 H), 8.02 (dd, J ) 8.2 Hz, J ) 1.2 Hz, 2 H), 8.71 (dd, J )
8.4 Hz, J ) 0.4 Hz, 2 H), 8.86 (dd, J ) 8.4 Hz, J ) 0.4 Hz, 2
H); 13C NMR δ 110.91 (s), 121.77 (d), 122.64 (d), 123.43 (d),
123.53 (d), 124.78 (d), 125.05 (s), 126.35 (s), 126.57 (d), 127.01
(d), 127.43 (d), 131.26 (s), 132.29 (s), 138.84 (s); IR (CHCl3) ν
3477 and 3678 (NH) cm-1; MS (EI) m/z (%) 384 ([M]+•, 100),
368 (25), 367 (53), 366 (18), 365 (23), 190 (10), 184 (10), 183.5
(34), 183 (23), 182.5 (40), 176 (20); HRMS for C28H20N2 calcd
384.1626 found 384.1620.
9H-Tetr a ben zo[a ,c,g,i]ca r ba zole (19). Meth od A (Oxi-
d a tive Cou p lin g): mp 257-8 °C (toluene; lit.17 gives 242-4
°C); 1H NMR (400 MHz, acetone-d6) δ 7.62-7.68 (m, 2 H),
7.69-7.78 (m, 6 H), 8.74 (dd, J ) 8 Hz, J ) 1.2 Hz, 2 H), 8.91
(d, J ) 8.4 Hz, 4 H), 9.09 (d, J ) 8 Hz, 2 H), 12.08 (bs, 1 H);
13C NMR (101 MHz, CDCl3) δ 115.33 (s), 122.58 (d), 123.34
(s), 124.15 (d), 124.61 (d), 124.67 (d), 125.18 (d), 126.37 (d),
126.42 (d), 127.46 (d), 127.69 (s), 128.98 (s), 129.34 (s), 133.38
(s); MS (EI) m/z (%) 367 ([M]+•, 100); HRMS for C28H17N calcd
367.1361 found 367.1357.
9H-Dip h en a n th r o[1,2-c:2′,1′-g]ca r ba zole (21): mp >320
°C (dec); 1H NMR (400 MHz, CDCl3) δ 6.32 (ddd, J ) 8.3, 6.7,
and 1.5 Hz, 2 H), 7.12 (ddd, J ) 8.0, 6.9, and 1.2 Hz, 2 H),
7.57 (d, J ) 8.4 Hz, 2 H), 7.77-7.86 (m, 6 H), 8.00 (d, J ) 8.7
Hz, 2 H), 8.52 (dd, J ) 8.4 and 1.6 Hz, 2 H), 8.86 (d, J ) 8.7
Hz, 2 H), 8.96 (dd, J ) 8.1 and 1.5 Hz, 2 H), 10.17 (bs, 1 H,
NH); 13C NMR δ 115.94 (s), 120.41 (d), 120.75 (d), 122.02 (s),
123.33 (d), 124.35 (d), 124.53 (s), 125.06 (d), 125.73 (d), 126.09
(d), 126.29 (d), 126.61 (d), 127.07 (s), 128.63 (d), 129.60 (s),
130.61 (s), 131.19 (s), 133.28 (s); IR (CHCl3) ν 3467 cm-1; MS
(ES) m/z (%) 466 ([M]+ - 1, 100).
3-P h en yl-1-h yd r a zin on a p h th a len e (22) was obtained
along with 11 on reaction of 3a with hydrazine hydrate: mp
(hydrochloride) 136-8 °C; 1H NMR δ 4.59 (m, 2 H, NH2), 6.02
(m, 1 H, NH), 7.25 (bs, 1 H, 2-H), 7.38 (tt, J ) 7.5 and 1.5 Hz,
4′-H), 7.45 (m, 1 H, 7-H), 7.48 (m, 2 H, 3′-H and 5′-H), 7.49
(m, 1 H, 6-H), 7.54 (bs, 1 H, 4-H), 7.74 (m, 2 H, 2′-H and 6′-H),
7.78 (dm, J ) 8.1 Hz, 1 H, 8-H), 7.87 (dm, J ) 8.1 Hz, 1 H,
5-H); 13C NMR δ 104.19 (d, C-2), 117.44 (d, C-4), 119.50 (d,
C-8), 121.81 (s, C-9), 125.16 (d, C-7), 126.41 (d, C-6), 127.31
(d, C-4′), 127.37 (2 × d, C-2′ and C-6′), 128.71 (2 × d, C-3′ and
C-5′), 128.91 (d, C-5), 134.35 (s, C-10), 139.11 (s, C-3), 141.73
(s, C-1′), 146.54 (s, C-1); IR (CHCl3) ν 3417, 3394 and 3343
(NH), 1628 and 1596 (CdC arom) cm-1; MS (EI) m/z (%) 234
([M]+•, 100), 218 (M - NH2, 36.9), 204 (M - N2H3, 16.3), 191
(M - CN2H3, 56.3), 189 (16.0), 176 (2.9), 165 (8.8), 140 (3.4),
117 (3.5).
Meth od B. A mixture of 9-phenanthrol (5.00 g) and 80%
aqueous hydrazine hydrate (0.8 mL) was heated in a sealed
tube at 180 °C for 24 h. The mixture was cooled and dissolved
in dichloromethane, and the solution was worked up. Chro-
matography on silica gel (50 g) with toluene gave 19 (2.88 g,
58%), which had identical MS and NMR spectra as those
obtained for the product resulting from Method A.
Oxid a tive Cou p lin g of 11. The oxidative coupling was
carried out as described in the general procedure, using 11
(2.19 g). After workup, the residue was chromatographed on
a column of silica gel (50 g) using toluene as eluent to give
carbazole 20 (505 mg, 25%).
6,7-Diph en yl-13H-diben zo[a ,i]car bazole (20): mp 294-6
°C (sublim); 1H NMR (400 MHz, CDCl3) δ 6.95-7.00 (m, 6 H),
7.15-7.20 (m, 4 H), 7.41 (s, 2 H), 7.54 (ddd, J ) 8.2, 7.0, and
1.2 Hz, 2 H), 7.64 (ddd, J ) 8.2, 7.0, and 1.4 Hz, 2 H), 7.96
(dm, J ) 8.1 Hz, 2 H), 8.33 (dm, J ) 8.2 Hz, 2 H), 9.76 (bs, 1
H, NH); 13C NMR δ 117.34 (s), 119.90 (d), 120.26 (s), 123.31
Ack n ow led gm en t. We thank the Grant Agency of
the Czech Republic for grant No. 203/00/0601, the Grant
Agency of the Charles University for grant No 18/98,
the Ministry of Education of the Czech Republic for
grants No. VS 96140 and LB 98233, and the EPSRC
and Merck Sharp & Dohme for a CASE award (to
R.D.B.).
Su p p or tin g In for m a tion Ava ila ble: Details of the crys-
tallographic analysis with fully labeled ORTEP diagram for
20, atomic coordinates, selected bond lengths and angles,
anisotropic displacement parameters, and hydrogen coordi-
nates. This material is available free of charge via the Internet
at http://pubs.acs.org.
J O005691W