Carbon-carbon bond formation reaction of zirconacyclopentadienes with alkynes in the presence of Ni(II)-complexes

Article abstract of DOI:10.1021/ja990750c

Zirconacyclopentadienes, prepared from two alkynes or a diyne, reacted with the alkyl-, trimethylsilyl-, or alkoxy-substituted third alkyne as well as an alkyne with an electron-withdrawing group in the presence of a stoichiometric amount of NiBr₂(PPh₃)₂ to give benzene derivatives in good yields. Heteroatom-containing diynes such as dipropargylbenzylamine and propargyl-homopropargylbenzylamine gave isoindoline and tetrahydroisoquinoline derivatives in good to high yields. This procedure was also used for the selective preparation of benzene derivatives from three different alkynes. The use of trimethylsilyl-substituted alkyne as the first, second or third alkyne afforded desilylated benzene derivatives. The reaction of zirconacyclopentadienes with allenes gave benzene derivatives as a mixture of two isomers.

Full text of DOI:10.1021/ja990750c

J. Am. Chem. Soc. 1999, 121, 11093-11100
11093
Carbon-Carbon Bond Formation Reaction of
Zirconacyclopentadienes with Alkynes in the Presence of
Ni(II)-complexes
Tamotsu Takahashi,* Fu-Yu Tsai, Yanzhong Li, Kiyohiko Nakajima,† and Martin Kotora
Contribution from the Catalysis Research Center and Graduate School of Pharmaceutical Sciences,
Hokkaido UniVersity, Kita-ku, Sapporo 060-0811Japan, and CREST, Science and Technology Corporation
(JST), Sapporo 060-0811, Japan
ReceiVed March 8, 1999
Abstract: Zirconacyclopentadienes, prepared from two alkynes or a diyne, reacted with the alkyl-, trimethylsilyl-,
or alkoxy-substituted third alkyne as well as an alkyne with an electron-withdrawing group in the presence of
a stoichiometric amount of NiBr2(PPh3)2 to give benzene derivatives in good yields. Heteroatom-containing
diynes such as dipropargylbenzylamine and propargyl-homopropargylbenzylamine gave isoindoline and
tetrahydroisoquinoline derivatives in good to high yields. This procedure was also used for the selective
preparation of benzene derivatives from three different alkynes. The use of trimethylsilyl-substituted alkyne
as the first, second or third alkyne afforded desilylated benzene derivatives. The reaction of zirconacyclopen-
tadienes with allenes gave benzene derivatives as a mixture of two isomers.
Introduction
Transition-metal-catalyzed or -mediated coupling of three
alkynes to give benzene derivatives has been well established
in organic synthesis.1,2 Despite intense research in this area, the
problem of the selective intermolecular coupling of three alkynes
has remained virtually unsolved. Recently, we have reported
that this problem can be overcome by the reaction of zircona-
cyclopentadienes, which can be selectively prepared from two
different alkynes,3 with alkynes bearing electron-withdrawing
groups in the presence of a stoichiometric amount of CuCl (eq
1).4 This method was the first example of the one-pot formation
of benzene derivatives from three different alkynes in high yields
(83-95%) with excellent selectivities.4a However, the critical
limitation of this method is that at least one electron-withdrawing
group is required for the third alkyne, since the major reaction
step of this method is Michael addition of the dienylcopper
species to the third alkyne. Therefore, consequently, an alkyne
with electron-donating groups such as alkyl, trimethylsilyl, and
alkoxy groups cannot be used for this reaction.
One reasonable approach to overcome this difficulty is
development of an insertion reaction of the third alkyne into a
dienylmetal and such insertion reaction can be expected for the
late transition-metal compounds such as nickel. Therefore, we
have investigated a novel and general reaction system using
zirconacyclopentadienes and the late transition-metal com-
pounds. In this paper we would like to report a novel reaction
of zirconacyclopentadienes with the third alkynes which have
electron-donating groups as well as an electron-withdrawing
group in the presence of Ni(II)-complexes to afford benzene
derivatives (eq 2). This can be a general one-pot procedure for
the selectiVe synthesis of benzene deriVatiVes by intermolecular
coupling of alkynes or by intramolecular coupling of diynes.
† Department of Chemistry, Aichi University of Education, Igaya, Kariya,
448-8542, Japan, and CREST, Science and Technology Corporation (JST),
Kariya 448-8542, Japan
(1) (a) Lautens, M.; Klute, W.; Tam, W. Chem. ReV. 1996, 96, 49-92.
(b) Grotjahn, D. B. ComprehensiVe Organometallic Chemistry II; Abel, E.
W., Stone, F. G. A., Wilkinson, G., Eds.; Elsevier Science Ltd: Oxford,
1995; Vol 12; pp 741-770. (c) Schore, N. E. ComprehensiVe Organic
Synthesis; Trost, B. M., Fleming, I., Eds; Pergamon Press Ltd: Oxford,
1991; Vol. 5; pp 1129-1162. (d) Harrington, P. J. Transition Metals in
Total Synthesis, John Wiley & Sons: New York, 1990; pp 200-240. (e)
Schore, N. E. Chem. ReV. 1988, 88, 1081-1119. (f) Vollhardt, K. P. C.
Angew. Chem., Int. Ed. Engl. 1984, 23, 539-556.
(2) (a) Boese, R.; Van Sickle, A. P.; Vollhardt, K. P. C. Synthesis 1994,
1374-1382. (b) Saa, C.; Crotts, D. D.; Hsu, G.; Vollhardt, K. P. C. Synlett
1994, 487-489. (c) Lecker, S. H.; Nguyen, N. H.; Vollhardt, K. P. C. J.
Am. Chem. Soc. 1986, 108, 856-858. (d) Hillard, R. L., III; Parnell, C. A.;
Vollhardt, K. P. C. Tetrahedron 1983, 39, 905-911. (e) Funk, R. L.;
Vollhardt, K. P. C. J. Am. Chem. Soc. 1980, 102, 5253-5261. (f) Wakatsuki,
Y.; Kuramitsu, T.; Yamazaki, H. Tetrahedron Lett. 1974, 4549-4552.
(3) (a) Xi, Z.; Hara, R.; Takahashi, T. J. Org. Chem. 1995, 60, 4444-
4447. (b) Takahashi, T.; Xi, Z.; Rousset, C. J.; Suzuki, N. Chem. Lett. 1993,
1001-1002. For other methods see: (c) Takahashi, T.; Swanson, D. R.;
Negishi, E. Tetrahedron Lett. 1987, 28, 623-626. (d) Buchwald, S. L.;
Nielsen, R. B. J. Am. Chem. Soc. 1989, 111, 2870-2874. (e) Wagenen, B.
C. V.; Livinghouse, T. Tetrahedron Lett. 1989, 30, 3495-3498. (f)
Takahashi, T.; Kageyama, V.; Denisov, V.; Hara, R.; Negishi, E. Tetra-
hedron Lett. 1993, 34, 687-690.
(4) For formation of benzene derivatives from three different alkynes
via transmetalation of zirconacyclopentadienes to organocopper, see (a)
Takahashi, T.; Xi, Z.; Yamazaki, A.; Liu, Y.; Nakajima, K.; Kotora, M. J.
Am. Chem. Soc. 1998, 120, 1672-1680. (b) Takahashi, T.; Kotora, M.; Xi,
Z. J. Chem. Soc., Chem. Commun. 1995, 361-362. For other examples of
transmetalations of zirconacycles to organocopper compounds, see: (c)
Takahashi, T.; Kotora, M.; Kasai, K.; Suzuki, N.; Nakajima, K. Organo-
metallics 1994, 13, 4183-4185. (d) Kasai, K.; Kotora, M.; Suzuki, N.;
Takahashi, T.; J. Chem. Soc., Chem. Commun. 1995, 109-110. (e)
Takahashi, T.; Kotora, M.; Xi, Z. J. Chem. Soc., Chem. Commun. 1995,
1503-1504. (f) Takahashi, T.; Hara, R.; Nishihara, Y.; Kotora, M. J. Am.
Chem. Soc. 1996, 118, 5154-5155. (g) Takahashi, T.; Xi, Z.; Kotora, M.;
Xi, C.; Nakajima, K. Tetrahedron Lett. 1996, 37, 7521-7524. (h) Takahashi,
T.; Nishihara, Y.; Hara, R.; Huo, S.; Kotora, M. Chem. Commun. 1997,
1599-1600. (i) Kotora, M.; Umeda, C.; Ishida, T.; Takahashi, T. Tetra-
hedron Lett. 1997, 38, 8355-8358. (j) Kotora, M.; Xi, C.; Takahashi, T.
Tetrahedron Lett. 1998, 39, 4321-4324. (k) Takahashi, T.; Sun, W.-H.;
Liu, Y.; Nakajima, K.; Kotora, M. Organometallics 1998, 17, 3841-3843.
10.1021/ja990750c CCC: $18.00 © 1999 American Chemical Society
Published on Web 11/19/1999

11094 J. Am. Chem. Soc., Vol. 121, No. 48, 1999
Takahashi et al.
Table 1. Ni-Complex-Mediated Reaction of
Zirconacyclopentadienes with Alkyl-, Aryl-, or
Trimethylsilyl-Substituted Alkynes
Transmetalation of zirconacycles to other organometallic
compounds has been used for further C-C bond formations.
In particular, transmetalation from zirconacycles to copper or
lithium has been intensively investigated by our group and
others.4-6 The transmetalation reaction of zirconacycles to nickel
compounds has not been reported yet, although the coupling
reaction of alkenylzirconocene with organic halides or Michael
addition to R,â-enones in the presence of nickel compounds is
known.7
Results and Discussion
Reaction of Zirconacyclopentadienes with Alkyl-, Aryl-,
Trimethylsilyl-, or Alkoxy-Substituted Alkynes. Addition of
1 equiv of NiBr2(PPh3)2 to a mixture of tetraethylzirconacy-
clopentadiene 1a and 3-hexyne in THF at 20 °C resulted in the
formation of hexaethylbenzene 3a in 1 h in 73% yield (eq 3)
along with the precipitation of metallic nickel. It is in sharp
contrast to the reaction of 1a in the presence of CuCl where
3-hexyne does not react with 1a.
This result encouraged us to investigate the reactions of both
mono- and bicyclic zirconacyclopentadienes with alkyl-, aryl-,
trimethylsilyl-, or alkoxy-substituted alkynes. The results are
summarized in Table 1. The reaction of tetraethylzirconacyclo-
pentadiene with 4-octyne (entry 1) gave 3b as a single product.
The reaction of bicyclic zirconacyclopentadienes gave the
corresponding indan (entries 2-4) and tetrahydronaphthalene
derivatives (entry 5). It is interesting to note that terminal alkynes
could be used as well (entries 6 and 7). In the case of CuCl-
mediated coupling reaction, the use of terminal alkynes did not
give a satisfactory result even with an electron-withdrawing
a GC yields. Isolated yields are given in parentheses.
group. The reaction with trimethylsilylpropyne (entry 8) afforded
the desired product; however, it was rather unstable and
underwent desilylation during the isolation by column chroma-
tography. Desilylated compound 3i was obtained as a pure
product in 53% yield. It is noteworthy that in all cases the
formation of homotrimerization products of the third alkynes
was not observed.
(5) (a) Lipshutz, B. H.; Segi, M. Tetrahedron 1995, 51, 4407-4420. (b)
Honda, T.; Mori, M. Organometallics 1996, 15, 5464-5466. (c) Dekura,
F.; Honda, T.; Mori, M. Chem. Lett. 1997, 825-826.
(6) For the reaction of zirconacyclopentadienes with organolithium,
see: (a) Takahashi, T.; Huo, S.; Hara, R.; Noguchi, Y.; Nakajima, K.; Sun,
W.-H. J. Am. Chem. Soc. 1999, 121, 1094-1095. For the reaction of
zirconacyclopentanes with organolithium compounds, see: (b) Luker, T.;
Whitby, R. J. Tetrahedron Lett. 1994, 35, 785-788. (c) Luker, T.; Whitby,
R. J. Tetrahedron Lett. 1994, 35, 9465-9469. (d) Luker, T.; Whitby, R. J.
Tetrahedron Lett. 1995, 36, 4109-4112. (e) Gordon, G. J.; Whitby, R. J.
Synlett 1995, 77. (f) Fillery, S.; Gordon, G. J.; Luker, T.; Whitby, R. J.
Pure Appl. Chem. 1997, 69, 639-644. (g) Kondakov, D. Y.; Negishi, E. J.
Chem. Soc., Chem. Commun. 1996, 963.
As far as nickel complexes were concerned, NiBr2(PPh3)2
gave the best result. The use of other nickel complexes such as
NiCl2(dppe), NiBr2(dppb), and NiBr2 did not give benzene
derivatives due to the poor solubility of the Ni complexes. NiCl2-
(dppe), NiBr2(dppb), and NiBr2 were not soluble in THF at room
temperature. In a mixture of THF and CH2Cl2, use of NiBr2-
(dppb) gave 3a in 39% yield. NiCl2(dppe) afforded precipitated
solid at reflux in THF (vide infra).
(7) For transmetalations of organozirconium compounds to organonickel
compounds, see: (a) Loots, M. J.; Schwartz, J J. Am. Chem. Soc. 1977,
99, 8045-8046. (b) Negishi, E.; Van Horn, D. E. J. Am. Chem. Soc. 1977,
99, 3168-3170. (c) Negishi, E.; Okukado, N.; King, A. O.; Van Horn, D.
E.; Speigel, B. I. J. Am. Chem. Soc. 1978, 100, 2254-2256. (d) Schwartz,
J.; Loots, M. J.; Kosugi, H. J. Am. Chem. Soc. 1980, 102, 1333-1340. (e)
Dayrit, F. M.; Gladkowski, D. E.; Schwartz, J. J. Am. Chem. Soc. 1980,
102, 3976-3978. (f) Dayrit, F. M.; Schwartz, J. J. Am. Chem. Soc. 1981,
103, 4466-4473. (g) Coffen, D. L.; Manchand, P. S.; Truesdale, L. K.
Eur. Patent Appl. Ep 153689, 1985; Chem. Abstr. 1986, 104, 186231v. (h)
Negishi, E.; Takahashi, T.; Baba, S.; Van Horn, D. E.; Okukado, N. J. Am.
Chem. Soc. 1987, 109, 2393-2401. (i) Hauske, J. R.; Dorff, P.; Julin, S.;
Martinelli, G.; Bussolari, J. Tetrahedron Lett. 1992, 33, 3715-3716. (j)
Hauske, J. R.; Dorff, P.; Julin, S.; DiBrino, J.; Spencer, R.; Williams, R. J.
Med. Chem. 1992, 35, 4284-4296. (k) Sun, R. C.; Okabe, M.; Coffen, D.
L.; Schwartz, J. Org. Synth. 1993, 71, 83-88.
To know the generality of this reaction, we investigated the
reactions of 1a with alkynes with an electron-withdrawing group
such as COOEt and COMe groups and with an electron-donating
group such as EtO and BuO groups. The results are shown in
Table 2. In all cases the yields were comparable. The reaction
of 1a with both ethoxycarbonyl- and methylcarbonyl-substituted
alkynes (entries 3 and 4) completed in much shorter reaction
time when compared with the procedure using CuCl.3a Conju-
gated alkyne such as 3,5-octadiyne also gave the desired product,
1-pentaethylphenyl-1-butyne 3n in 69% yield. Further reaction
of 3n with 1a was not observed. The formation of arenes was
also possible by the reaction with conjugated diynes (entry 5).

C-C Bond Formation in Zirconacyclopentadienes
J. Am. Chem. Soc., Vol. 121, No. 48, 1999 11095
Table 2. Ni-complex-Mediated Reaction of
Zirconacyclopentadienes with Functionalized Alkynes
Figure 1.
of two regioisomers 4h and 4i in a 1:1 ratio (eq 6). This is
a GC yields. Isolated yields are given in parentheses.
Formation of Isoindolines and Tetrahydroisoquinoline.
This Ni-mediated formation of arenes was applied to the
synthesis of highly substituted benzo-type heterocycles with a
5-, 6-, and 7-membered ring (eq 4).8 Some representative
because the terminal alkyne could not recognize the difference
between the phenyl group and the propyl group of the
zirconacyclopentadienes by this system. Compound 4i was
isolated as crystals, and its single-crystal X-ray analysis was
performed to confirm the structure (Figure 1). The problem of
the regioselectivity of the reaction with a terminal alkyne can
be circumvented by the preparation of unsymmetrical trimeth-
ylsilyl-substituted zirconacyclopentadienes followed by desilyla-
tion. It is well-known that trimethylsilylacetylene affords unsym-
metrical zirconacyclopentadienes by the reaction with other
alkynes such as 3-hexyne and 4-octyne with an excellent regio-
selectivity. These zirconacyclopentadienes were converted into
benzene derivatives with the third alkynes in the presence of a
nickel compound. These products upon isolation underwent
facile desilylation to give the corresponding pentasubstituted
benzenes 4f and 4g (eq 7) as single products.
examples are given in Table 3. Isoindoline 3o-3r (entries 1-4),
tetrahydroisoquinoline 3s and 3t (entries 5 and 6), and benzop-
erhydroazepine 3u (entry 7) derivatives were prepared.
Preparation of Benzenes from Three Different Alkynes.
One attractive target of intermolecular coupling of three alkynes
is the preparation of benzene derivatives from three different
alkynes. We have already reported the zirconacyclopentadienes/
CuCl system as mentioned above. However, the system with
nickel compounds reported here is more general and useful for
the preparation of benzene derivatives from three different
alkynes (eq 5). This reaction can be done in one-pot.
Reaction with Allenes. The nickel-mediated reaction pro-
ceeds also with allenes; however, in this case a mixture of
compounds 5 and 6 was obtained as shown (eq 8). The
Results are summarized in Table 4. For example, the
preparation of benzene having methyl, ethyl, and propyl groups
4c (entry 3) was achieved in good yield (63%) in a simple
reaction sequence. On the other hand, the reaction of unsym-
metrically substituted zirconacyclopentadiene with a terminal
acetylene such as tert-butylacetylene resulted in the formation
formation of 5 arises from the attack to the internal double bond
of the allene moiety, and the formation of 6 arises from the
attack to the terminal double bond of the allene moiety.
Reaction Mechanism. Monitoring the reaction by 1H NMR
did not show any significant intermediate except the formation
of zirconocene dibromide. However, the following two reaction
(8) Transition-metal-mediated formation of benzo-type nitrogen-contain-
ing heterocycles from diynes, for Rh, see: (a) Muller, E. Synthesis 1974,
761. For Ni, see: (b) Chiusoli, G. P.; Pallini, L.; Terenghi, G. Transition
Met. Chem. 1983, 8, 189. For Co, see: (c) ref 2d.

11096 J. Am. Chem. Soc., Vol. 121, No. 48, 1999
Takahashi et al.
Table 3. Ni-complex-Mediated Formation of Benzoheterocycles from Zirconacyclopentadienes
a NMR yields. Isolated yields are given in parentheses.
Table 4. Formation of Arenes from Three Alkynes
Scheme 1
mechanisms, path A and path B, are plausible (Scheme 1). In
path A, one of the Zr-C bonds transmetalates to give a
bimetallic intermediate 7 in which one alkyne inserts into the
C-Ni bond giving a bimetallic triene intermediate 8. Intramo-
lecular transmetalation of the second Zr-C bond affords the
nickelacycloheptatriene 9 and zirconocene dibromide. Reductive
coupling of 9 gives the benzene derivatives. In path B, both
Zr-C bonds transmetalate simultaneously to give nickelacy-
clopentadiene 10 and zirconocene dibromide. The insertion of
an alkyne into one of the C-Ni bonds affords the nickelacy-
cloheptatriene 9. Then compound 9 undergoes reductive elimi-
nation to give benzene derivatives 3-4 and a Ni0-complex that
decomposes to metallic nickel and free ligands.
When tetraphenylzirconacyclopentadiene 1b was treated with
NiCl2(dppe) at reflux in THF for 24 h, brick-red solid 10b was
precipitated along with the formation of Cp2ZrCl2 in 94% NMR
yield as shown in Scheme 2. IR spectrum of the red solid
showed the characteristic resonance at 1585 cm-1 which was
consistent with that observed for tetraphenylnickelacyclopen-
tadiene 10b which has been prepared by the reaction of NiCl2-
a GC yields. Isolated yields are given in parentheses.

C-C Bond Formation in Zirconacyclopentadienes
J. Am. Chem. Soc., Vol. 121, No. 48, 1999 11097
(t, J ) 7.5 Hz, 6H), 2.0-2.1 (m, 2H), 2.61 (q, J ) 7.5 Hz, 4H), 2.66
(q, J ) 7.5 Hz, 4H), 2.89 (t, J ) 7.5 Hz, 4H); 13C NMR (CDCl3, Me4-
Si) δ 14.67 (2C), 16.17 (2C), 21.78 (2C), 23.58 (2C), 24.41, 31.73
(2C), 135.68 (2C), 137.79 (2C), 140.41 (2C); HRMS calcd for C17H26
230.2033; found 230.2037.
Scheme 2
4,7-Diethyl-5,6-dipropylindan (3d): Colorless oil. GC yield: 81%.
1
Isolated yield: 67%. H NMR (CDCl3, Me4Si) δ 1.26 (t, J ) 7.3 Hz,
6H), 1.34 (t, J ) 7.5 Hz, 6H), 1.71-1.74 (m, 4H), 2.20-2.27 (m, 2H),
2.74-2.78 (m, 4H), 2.79 (q, J ) 7.5 Hz, 4H), 3.08 (t, J ) 7.4 Hz,
4H); 13C NMR (CDCl3, Me4Si) δ 14.65 (2C), 15.04 (2C), 23.71 (2C),
24.40, 25.31 (2C), 31.62 (2C), 31.74 (2C), 135.73 (2C), 136.67 (2C),
140.30 (2C); HRMS calcd for C19H30 258.2346; found 258.2340.
4-Butyl-5,6-diethyl-7-phenylindan (3e): Pale yellow oil. GC
1
yield: 90%. Isolated yield: 76%. H NMR (CDCl3, Me4Si) δ 0.94 (t,
J ) 7.5 Hz, 3H), 0.99 (t, J ) 7.5 Hz, 3H), 1.21 (t, J ) 7.5 Hz, 3H),
1.47-1.56 (m, 4H), 1.89-1.96 (m, 2H), 2.45-2.53 (m, 4H), 2.61-
2.65 (m, 2H), 2.71 (q, J ) 7.5 Hz, 2H), 2.92 (t, J ) 7.5 Hz, 2H),
7.19-7.22 (m, 2H), 7.25-7.29 (m, 1H), 7.33-7.37 (m, 2H); 13C NMR
(CDCl3, Me4Si) δ 13.97, 15.97, 16.18, 21.91, 22.89, 23.52, 24.51, 30.59,
32.08, 32.78, 32.98, 126.24, 127.94 (2C), 129.28 (2C), 136.15, 136.56,
137.72, 138.05, 140.13, 140.51, 141.85; HRMS calcd for C23H30
306.2346; found 306.2351.
4,7-Diethyl-5,6-dipropyltetrahydronaphthalene (3f): Colorless oil.
GC yield: 66%. Isolated yield: 46%. 1H NMR (CDCl3, Me4Si) δ 1.26
(t, J ) 7.3 Hz, 6H), 1.34 (t, J ) 7.5 Hz, 6H), 1.70-1.80 (m, 4H),
1.95-2.10 (m, 4H), 2.72-2.78 (m, 4H), 2.81 (q, J ) 7.5 Hz, 4H),
2.90-2.97 (m, 4H); 13C NMR (CDCl3, Me4Si) δ 14.49 (2C), 15.12
(2C), 21.86 (2C), 23.26 (2C), 25.05 (2C), 27.08 (2C), 31.90 (2C),
132.95 (2C), 136.16 (2C), 138.05 (2C); HRMS calcd for C20H32
272.2502; found 272.2503.
(dppe) with 1,4-dilithio-1,2,3,4-tetraphenyl-1,3-butadiene.9 Treat-
ment of the red solid 10b with acetic acid gave 1,2,3,4-tetra-
phenyl-1,3-butadiene quantitatively and the reaction with 4-
octyne afforded the corresponding 1,2-dipropyl-3,4,5,6-tetraphe-
nylbenzene in 54% isolated yield as expected.10
This result clearly suggests that zirconacyclopentadienes
reacted with nickel complexes to form nickelacyclopentadienes
and Cp2ZrX2 and strongly supports the path B in Scheme 1.
However, the existence of the path A cannot be ruled out.
Experimental Section
General Information. All reactions involving air- or moisture-
sensitive organometallic reagents were carried out under dry nitrogen.
THF was distilled from sodium benzophenone ketyl. Zirconocene
dichloride was purchased from Aldrich Chemical Co., Inc. Butyllithium
(1.6 M solution in hexane) was purchased from Kanto Chemical Co.
Ltd. Alkynes were purchased from TCI Co. Ltd. Nickel(II) complexes,10a
phenylpropadiene, and 1,2-octadiene11 were prepared according to the
previously published procedure.
1,2,3,4-Tetraethyl-5-propylbenzene (3 g): Colorless oil. GC
1
yield: 70%. Isolated yield: 60%. H NMR (CDCl3, Me4Si) δ 1.01 (t,
J ) 7.3 Hz, 3H), 1.15 (t, J ) 7.5 Hz, 6H), 1.17 (t, J ) 7.5 Hz, 3H),
1.22 (t, J ) 7.5 Hz, 3H), 1.60-1.66 (m, 2H), 2.53-2.59 (m, 2H), 2.59-
2.70 (m, 8H), 6.86 (s, 1H); 13C NMR (CDCl3, Me4Si) δ 14.53, 15.59
(2C), 15.67, 15.93, 21.74, 21.81, 22.06, 24.79, 25.65, 35.26, 127.35,
137.36, 137.47, 138.10, 139.24, 139.76; HRMS calcd for C17H28
232.2190; found 232.2187.
1H and 13C NMR spectra were recorded for CDCl3 or C6D6
(containing 1% TMS) solutions at 25 °C on Bruker NMR spectrometer.
GC analysis was performed on Shimadzu GC-14A equipped with fused
silica capillary column Shimadzu CBP1-M25-O25 and Shimadzu
C-R6A-Chromatopac integrator.
5-Phenyl-4,7-diethylindan (3h): Pale yellow oil. GC yield: 78%.
1
Isolated yield: 64%. H NMR (CDCl3, Me4Si) δ 1.00 (t, J ) 7.5 Hz,
3H), 1.21 (t, J ) 7.6 Hz, 3H), 2.08-2.15 (m, 2H), 2.53 (q, J ) 7.5
Hz, 2H), 2.59 (q, J ) 7.6 Hz, 2H), 2.91 (t, J ) 7.4 Hz, 2H), 2.95 (t,
J ) 7.4 Hz, 2H), 6.88 (s, 1H), 7.28-7.37 (m, 5H); 13C NMR (CDCl3,
Me4Si) δ 14.23, 14.62, 23.62, 24.85, 26.19, 31.19, 31.69, 126.37,
127.62, 127.80 (2C), 129.39 (2C), 134.85, 136.73, 140.23, 141.58,
142.69, 142.84; HRMS calcd for C19H22 250.1720; found 250.1717.
4,7-Diethyl-5-methyltetrahydronaphthalene (3i): Pale yellow oil.
Typical experimental procedure. To a solution of zirconacyclo-
pentadiene 1 (1.0 mmol)4,12 in 20 mL THF were added the third alkyne
(1.5 mmol) and NiBr2(PPh3)2 (0.74 g, 1.0 mmol) at room temperature.
The mixture was stirred for 1 h, quenched with 3N HCl, and extracted
with hexane. The combined organic extracts were dried (MgSO4) and
concentrated in vacuo. Column chromatography on silica gel (hexane)
afforded products. For the isolation of the following compounds
mixtures of hexane/Et2O were used: 3j, 3l, and 3m (19/1); 3o, 3q,
and 3r (4/1); 3p and 3s (6/1); 3t and 3u (5/1).
1
Isolated yield: 53%. H NMR (CDCl3, Me4Si) δ 1.05 (t, J ) 7.6 Hz,
3H), 1.14 (t, J ) 7.6 Hz, 3H), 1.71-1.74 (m, 4H), 2.24 (s, 3H), 2.49
(q, J ) 7.6 Hz, 2H), 2.56 (q, J ) 7.6 Hz, 2H), 2.60-2.65 (m, 2H),
2.68-2.73 (m, 2H), 6.80 (s, 1H); 13C NMR (CDCl3, Me4Si) δ 13.32,
14.30, 19.41, 21.81, 22.95, 23.30, 25.41, 26.46, 26.87, 127.38, 132.64,
132.68, 134.75, 138.06, 139.33; HRMS calcd for C15H22 202.1720;
found 202.1716.
Hexaethylbenzene (3a): White solid. GC yield: 73%. Isolated
1
yield: 57%. H and 13C NMR were in agreement with the published
data.13
1,2,3,4-Tetraethyl-5,6-dipropylbenzene (3b). White solid. GC
yield: 70%. Isolated yield: 49%. 1H NMR, (CDCl3, Me4Si) δ 1.05 (t,
J ) 7.2 Hz, 6H), 1.18 (t, J ) 7.3 Hz, 12H), 1.52-1.58 (m, 4H), 2.49-
1-Ethoxy-2,3,4,5-tetraethylbenzene (3j): Pale yellow oil. GC
2.65 (m, 4H), 2.61 (q, J ) 7.1 Hz, 4H), 2.63 (q, J ) 7.0 Hz, 4H); 13
C
1
yield: 64%. Isolated yield: 32%. H NMR (CDCl3, Me4Si) δ 1.13 (t,
NMR (CDCl3, Me4Si) δ 15.19 (2C), 15.75 (4C), 22.17 (2C), 22.31
(2C), 24.88 (2C), 32.08 (2C), 136.79 (2C), 137.74 (2C), 137.90 (2C).
Anal. Calcd for C20H34: C, 87.52; H, 12.48. Found: C, 87.38; H, 12.55.
4,5,6,7-Tetraethylindan (3c): Colorless oil. GC yield: 76%. Isolated
yield: 63%. 1H NMR (CDCl3, Me4Si) δ 1.15 (t, J ) 7.5 Hz, 6H), 1.18
J ) 7.5 Hz, 6H), 1.16 (t, J ) 7.5 Hz, 3H), 1.22 (t, J ) 7.4 Hz, 3H),
1.39 (t, J ) 7.0 Hz, 3H), 2.58-2.69 (m, 8H), 4.00 (q, J ) 7.0 Hz,
2H), 6.56 (s, 1H); 13C NMR (CDCl3, Me4Si) δ 14.74, 15.10, 15.68,
15.83, 15.85, 19.52, 21.40, 22.10, 26.09, 63.31, 109.60, 128.55, 131.58,
140.02, 140.90, 155.05. Anal. Calcd for C16H26O: C, 81.99; H, 11.18.
Found: C, 81.85; H, 11.09.
(9) Eisch, J. J.; Galle, J. E.; Aradi, A. A.; Boleslawski, M. P. J.
Organomet. Chem. 1986, 312, 399.
(10) (a) Venanzi, L. M. J. Chem. Soc. 1958, 719-724. (b) Hoberg, H.;
Richter, W. J. Organomet. Chem. 1980, 195, 355. (c) Eisch, J. J.; Galle, J.
E.; J. Organomet. Chem. 1975, 96, C23.
(11) Allenes were prepared according to the known procedure: Brands-
ma, L, Verkruijsse, H. D. Synthesis of Acetylenes, Allenes and Cumulenes;
Elsevier: Amsterdam, 1981.
1-Butoxy-2,3,4,5-tetraethyl-6-hexylbenzene (3k): Colorless oil. GC
1
yield: 66%. Isolated yield: 50%. H NMR (CDCl3, Me4Si) δ 0.90 (t,
J ) 7.0 Hz, 3H), 1.00 (t, J ) 7.4 Hz, 3H), 1.14-1.19 (m, 12H), 1.31-
1.36 (m, 4H), 1.40-1.44 (m, 2H), 1.50-1.57 (m, 4H), 1.76-1.80 (m,
2H), 2.53-2.55 (m, 2H), 2.57-2.65 (m, 8H), 3.76 (t, J ) 6.5 Hz, 2H);
13C NMR (CDCl3, Me4Si) δ 14.05, 14.08, 15.70, 15.87, 15.90, 15.96,
19.39, 20.18, 22.04 (2C), 22.16, 22.72, 27.45, 30.26, 31.47, 31.74,
32.76, 73.48, 132.10, 133.19, 135.61, 138.85, 139.01, 154.21; HRMS
calcd for C24H42O 346.3234; found 346.3264.
(12) Negishi, E.; Cederbaum, F. E.; Takahashi, T. Tetrahedron Lett. 1986,
27, 2829-2832.
(13) Jhingan, A. K.; Maier, W. F. J. Org. Chem. 1987, 52, 1161-1165.

11098 J. Am. Chem. Soc., Vol. 121, No. 48, 1999
Takahashi et al.
Ethyl 2-phenyl-3,4,5,6-tetraethylbenzene carboxylate (3l): White
solid. GC yield: 78%. Isolated yield: 54%. 1H and 13C NMR were in
agreement with the published data.4a
16.01, 20.89, 22.81, 28.50, 29.76, 50.19, 51.74 (2C), 54.48, 58.23,
130.50, 131.18, 132.67, 136.06, 136.59, 137.00, 169.21, 169.23; HRMS
calcd for C20H29NO4 347.20947, found 347.2088.
Pentaethylacetophenone (3m):14 White solid. GC yield: 68%.
N-Butyl-6,7,8,9-tetraethyl-3-benzoperhydroazepine (3u): Yellow
oil. NMR yield: 66%. Isolated yield: 58%. 1H NMR (C6D6, Me4Si) δ
0.92 (t, J ) 7.2 Hz, 3H), 1.09 (t, J ) 7.5 Hz, 6H), 1.15 (t, J ) 7.5 Hz,
6H), 1.25-1.40 (m, 2H), 1.4-1.5 (m, 2H), 2.30 (t, J ) 7.3 Hz, 2H),
2.5-2.55 (m, 4H), 2.64 (q, J ) 7.3 Hz, 4H), 2.66 (q, J ) 7.4 Hz, 4H),
2.9-3.0 (m, 4H); 13C NMR (C6D6, Me4Si) δ 14.34, 16.14 (2C), 16.31
(2C), 21.02, 22.79 (2C), 23.07 (2C), 29.73, 30.97 (2C), 56.05 (2C),
59.08, 136.98 (2C), 137.27 (2C), 139.38 (2C); HRMS calcd for C22H37N
315.29241, found 315.2917.
Representative Procedure from the Preparation of Benzenes
from Three Different Alkynes. Formation of 1,2-Dimethyl-3,4-
dipropyl-5,6-diphenylbenzene (4a). To solution of diethylzirconocene
(1.25 mmol) in THF (5 mL) was added diphenylacetylene (178 mg, 1
mmol), and the reaction mixture was stirred at 0 °C for 3 h. After the
addition of 2-butyne (108 mg, 2 mmol), the reaction mixture was
warmed to room temperature for 1 h, followed by the removal of the
solvent and unreacted 2-butyne. Then fresh THF (10 mL), 4-octyne
(165 mg, 1.5 mmol), and NiBr2(PPh3)2 (0.74 g, 1.0 mmol) were added
at room temperature. The mixture was stirred for 1 h, quenched with
3 N HCl, and extracted with hexane. The combined organic extracts
were dried (MgSO4) and concentrated in vacuo. Column chromatog-
raphy on silica gel (hexane) afforded the title compound as a colorless
oil. GC yield: 80%. Isolated yield: 62%. 1H NMR (CDCl3, Me4Si) δ
0.70 (t, J ) 7.4 Hz, 3H), 1.08 (t, J ) 7.4 Hz, 3H), 1.36-1.41 (m, 2H),
1.62-1.66 (m, 2H), 1.98 (s, 3H), 2.32 (s, 3H), 2.34-2.38 (m, 2H),
2.70-2.74 (m, 2H), 6.89-6.97 (m, 6H), 6.98-7.03 (m, 4H); 13C NMR
(CDCl3, Me4Si) δ 14.76, 14.93, 16.34, 18.36, 23.95, 24.85, 32.68, 33.27,
125.47, 125.52, 126.91 (2C), 127.15 (2C), 130.28 (2C), 130.48 (2C),
132.23, 134.18, 136.23, 138.22, 139.45, 139.64, 141.69, 142.02; HRMS
calcd for C26H30 342.2346, found 342.2345.
1
Isolated yield: 55%. H NMR (CDCl3, Me4Si) δ 1.14 (t, J ) 7.5 Hz,
6H), 1.17 (t, J ) 7.5 Hz, 9H), 2.40-2.50 (m, 4H), 2.51 (s, 3H), 2.61-
2.70 (m, 6H); 13C NMR (CDCl3, Me4Si) δ 15.67 (2C), 15.72, 16.24
(2C), 21.48 (2C), 21.95, 23.54 (2C), 33.25, 133.68 (2C), 138.24 (2C),
140.77, 141.50, 209.24.
1-(Butyn-1-yl)-2,3,4,5-pentaethylbenzene (3n): Pale yellow oil. GC
1
yield: 69%. Isolated yield: 63%. H NMR (CDCl3, Me4Si) δ 1.19 (t,
J ) 7.6 Hz, 3H), 1.21 (t, J ) 7.5 Hz, 6H), 1.25 (t, J ) 7.5 Hz, 3H),
1.51 (t, J ) 7.5 Hz, 6H), 2.47 (q, J ) 7.5 Hz, 2H), 2.61-2.67 (m,
6H), 2.84 (q, J ) 7.5 Hz, 4H); 13C NMR (CDCl3, Me4Si) δ 13.42,
14.19, 14.87 (2C), 15.79 (2C), 15.82, 22.23 (2C), 22.25, 24.82 (2C),
78.37, 96.97, 121.40, 137.19 (2C), 139.71, 142.04 (2C); HRMS calcd
for C20H30 270.2346, found 270.2340.
N-Benzyl-4,5,6,7-tetraethylisoindoline (3o): Colorless oil. NMR
yield: 88%. Isolated yield: 70%. 1H NMR (C6D6, Me4Si) δ 0.98 (t, J
) 7.6 Hz, 6H), 1.12 (t, J ) 7.5 Hz, 6H), 2.37 (q, J ) 7.6 Hz, 4H),
2.61 (q, J ) 7.5 Hz, 4H), 3.82 (s, 2H), 3.93 (s, 4H), 7.1-7.6 (m, 5H);
13C NMR (C6D6, Me4Si) δ 15.23 (2C), 16.57 (2C), 22.01 (2C), 23.71
(2C), 58.90 (2C), 60.79, 127.27, 128.73 (2C), 128.81 (2C), 134.17 (2C),
137.28 (2C), 138.30 (2C), 140.51; HRMS calcd for C23H31N 321.2455,
found 321.2453.
N-Butyl-4,5,6,7-tetraethylisoindoline (3p): Colorless oil. NMR
yield: 92%. Isolated yield: 68%. 1H NMR (C6D6, Me4Si) δ 0.96 (t, J
) 7.3 Hz, 3H), 1.06 (t, J ) 7.6 Hz, 6H), 1.14 (t, J ) 7.5 Hz, 6H),
1.35-1.48 (m, 2H), 1.50-1.65 (m, 2H), 2.47 (q, J ) 7.6 Hz, 4H),
2.63 (q, J ) 7.5 Hz, 4H), 2.65 (t, J ) 7.3 Hz, 2H), 3.92 (s, 4H); 13C
NMR (C6D6, Me4Si) δ 14.10, 14.99 (2C), 16.35 (2C), 20.71, 21.79
(2C), 23.54 (2C), 31.32, 56.12, 58.74 (2C), 133.83 (2C), 137.01 (2C),
138.02 (2C); HRMS calcd for C20H33N 287.2611, found 287.2619.
N-Butyl-5-carboxyethyl-6-phenyl-4,7-diethylisoindoline (3q): Col-
1,2-Diethyl-3,4-dipropyl-5,6-diphenylbenzene (4b): White solid.
GC yield: 74%. Isolated yield: 60%. 1H NMR (CDCl3, Me4Si) δ 0.69
(t, J ) 7.4 Hz, 3H), 0.92 (t, J ) 7.4 Hz, 3H), 1.09 (t, J ) 7.3 Hz, 3H),
1.28 (t, J ) 7.3 Hz, 3H), 1.35-1.37 (m, 2H), 1.64-1.68 (m, 2H), 2.31-
2.35 (m, 2H), 2.44 (q, J ) 7.3 Hz, 2H), 2.65-2.69 (m, 2H), 2.76 (q,
J ) 7.3 Hz, 2H), 6.93-7.00 (m, 6H), 7.01-7.05 (m, 4H); 13C NMR
(CDCl3, Me4Si) δ 14.83, 15.19, 15.68, 15.96, 22.45, 23.46, 24.71, 25.12,
32.14, 33.14, 125.40, 125.42, 126.83 (2C), 126.86 (2C), 130.50 (2C),
130.55 (2C), 136.62, 137.49, 138.12, 139.23, 139.77, 139.90, 141.77
(2C): Anal. Calcd for C28H34: C, 90.75; H, 9.25. Found: C, 90.68; H,
9.42.
1
orless oil. NMR yield: 90%. Isolated yield: 66%. H NMR (C6D6,
Me4Si) δ 0.72 (t, J ) 7.1 Hz, 3H), 0.84 (t, J ) 7.6 Hz, 3H), 0.98 (t,
J ) 7.3 Hz, 3H), 1.21 (t, J ) 7.6 Hz, 3H), 1.40-1.50 (m, 2H), 1.50-
1.65 (m, 2H), 2.30 (q, J ) 7.4 Hz, 2H), 2.60 (q, J ) 7.4 Hz, 2H), 2.65
(t, J ) 7.2 Hz, 2H), 3.82 (q, J ) 7.1 Hz, 2H), 3.90 (s, 2H), 3.92 (s,
2H), 6.95-7.25 (m, 3H) 7.25-7.45 (m, 2H); 13C NMR (C6D6, Me4Si)
δ 13.80, 14.32, 14.67, 15.17, 20.87, 23.95, 24.94, 31.52, 56.10, 58.33,
58.71, 60.28, 127.15, 127.79(2C), 130.45(2C), 132.57, 134.24, 134.37,
138.33, 138.97, 139.99, 140.61, 169.43; HRMS calcd for C25H33NO2
379.2510, found 379.2511.
1,2-Dimethyl-3,4-diethyl-5,6-dipropylbenzene (4c): Colorless oil.
GC yield: 63%. Isolated yield: 55%. 1H NMR (CDCl3, Me4Si) δ 1.04
(t, J ) 7.3 Hz, 3H), 1.05 (t, J ) 7.3 Hz, 3H), 1.13 (t, J ) 7.5 Hz, 3H),
1.17 (t, J ) 7.5 Hz, 3H), 1.47-1.56 (m, 4H), 2.20 (s, 3H), 2.21 (s,
3H), 2.53-2.58 (m, 4H), 2.64 (q, J ) 7.5 Hz, 2H), 2.68 (q, J ) 7.5
Hz, 2H); 13C NMR (CDCl3, Me4Si) δ 14.84, 14.89, 15.06, 15.94, 16.13,
16.32, 22.51, 22.93, 23.94, 25.08, 32.22, 32.68, 132.64, 132.78, 136.17,
136.96, 137.30, 137.94. Anal. Calcd for C18H30: C, 87.73; H, 12.27.
Found: C, 87.61; H, 12.41.
1,2-Dimethyl-3,4-diethyl-5,6-diphenylbenzene (4d): Colorless solid.
GC yield: 76%. Isolated yield: 58%. 1H NMR (CDCl3, Me4Si) δ 0.96
(t, J ) 7.4 Hz, 3H), 1.25 (t, J ) 7.4 Hz, 3H), 1.99 (s, 3H), 2.34 (s,
3H), 2.46 (q, J ) 7.4 Hz, 2H), 2.82 (q, J ) 7.4 Hz, 2H), 6.90-6.92
(m, 2H), 6.96-6.99 (m, 4H), 7.03-7.05 (m, 4H); 13C NMR (CDCl3,
Me4Si) δ 14.84, 15.82, 16.13, 18.34, 22.99, 23.61, 125.48, 125.56,
126.96 (2C), 127.16 (2C), 130.26 (2C), 130.50 (2C), 132.31, 134.15,
137.18, 139.32, 139.37, 139.71, 141.65, 141.98. Anal. Calcd for
C24H26: C, 91.67; H, 8.33. Found: C, 91.45; H, 8.42.
1,2-Dimethyl-3,4-diethyl-5,6-dibutylbenzene (4e): Colorless oil.
GC yield: 65%. Isolated yield: 44%. 1H NMR (CDCl3, Me4Si) δ 0.97
(t, J ) 7.0 Hz, 3H), 0.98 (t, J ) 7.0 Hz, 3H), 1.13 (t, J ) 7.4 Hz, 3H),
1.17 (t, J ) 7.4 Hz, 3H), 1.45-1.51 (m, 8H), 2.20 (s, 3H), 2.21 (s,
3H), 2.55-2.61 (m, 4H), 2.64 (q, J ) 7.4 Hz, 2H), 2.68 (q, J ) 7.4
Hz, 2H); 13C NMR (CDCl3, Me4Si) δ 13.87, 13.90, 14.85, 15.93, 16.14,
16.30, 22.46, 22.93, 23.47, 23.60, 29.47, 29.98, 32.84, 33.96, 132.60,
132.74, 136.17, 136.99, 137.30, 137.92; HRMS calcd for C20H34
274.2659; found 274.2659.
N-Butyl-5,6-diphenyl-4,7-diethylisoindoline (3r): Colorless oil.
NMR yield: 78%. Isolated yield: 60%. 1H NMR (C6D6, Me4Si) δ 0.94
(t, J ) 7.5 Hz, 6H), 1.00 (t, J ) 7.3 Hz, 3H), 1.45-1.55 (m, 2H),
1.55-1.65 (m, 2H), 2.40 (q, J ) 7.4 Hz, 4H), 2.70 (t, J ) 7.2 Hz,
2H), 4.03 (s, 4H), 6.80-7.20 (m, 10H); 13C NMR (C6D6, Me4Si) δ
14.35, 14.96 (2C), 20.94, 24.68 (2C), 31.60, 56.30, 58.93(2C), 126.19
(2C), 127.51 (4C), 130.86 (4C), 133.94 (2C), 138.71 (2C), 140.50 (2C),
141.40 (2C); HRMS calcd for C28H33N 383.2611, found 383.2614.
N-Butyl-1,2,3,4-tetrahydro-6,7,8-triethyl-5-methylisoquinoline (3s):
Colorless oil. NMR yield: 78%. Isolated yield: 65%. 1H NMR (C6D6,
Me4Si) δ 0.94 (t, J ) 7.4 Hz, 3H), 1.09 (t, J ) 7.5 Hz, 3H), 1.11 (t,
J ) 7.5 Hz, 3H), 1.15 (t, J ) 7.5 Hz, 3H), 1.3-1.48 (m, 2H), 1.5-
1.65 (m, 2H), 2.03 (s, 3H), 2.44 (t, J ) 7.2 Hz, 4H), 2.48-2.58 (m,
4H), 2.61-2.68 (m, 4H), 3.64 (s, 2H); 13C NMR (C6D6, Me4Si) δ 14.33,
14.74, 15.07, 15.27, 16.43, 21.00, 21.56, 22.26, 22.92, 29.14, 29.99,
51.33, 55.43, 58.74, 131.17, 131.71, 131.73, 135.68, 136.71, 137.98;
HRMS calcd for C20H33N 287.2611, found 287.2616.
N-Butyl-1,2,3,4-tetrahydro-6,7-dicarboxymethyl-8-ethyl-5-meth-
ylisoquinoline (3t): Yellow oil. NMR yield: 64%. Isolated yield: 55%.
1H NMR (C6D6, Me4Si) δ 0.94 (t, J ) 7.3 Hz, 3H), 1.17 (t, J ) 7.5
Hz, 3H), 1.25-1.4 (m, 2H), 1.4-1.55 (m, 2H), 2.09 (s, 3H), 2.35 (t,
J ) 7.3 Hz, 3H), 2.40 (s, 3H), 2.59 (q, J ) 7.5 Hz, 2H), 3.47 (s, 2H),
3.56 (s, 3H), 3.57 (s, 3H); 13C NMR (C6D6, Me4Si) δ 14.28, 15.01,
(14) (a) Hopff, H.; Wick, A. K. HelV. Chim. Acta 1960, 43, 1473-1480.
(b) Downton, P. A.; Mailvaganam, B.; Frampton, C. S.; Sayer, B. G.;
McGlinchey, M. J. J. Am. Chem. Soc. 1990, 112, 27-32.

C-C Bond Formation in Zirconacyclopentadienes
J. Am. Chem. Soc., Vol. 121, No. 48, 1999 11099
1-Methyl-3,4-diethyl-5,6-dipropylbenzene (4f): Pale yellow oil.
Isolated yield: 43%. H NMR (CDCl3, Me4Si) δ 1.03 (t, J ) 7.5 Hz,
2H), 2.70 (q, J ) 7.4 Hz, 4H), 2.73 (q, J ) 7.5 Hz, 2H), 7.16-7.18
(m, 2H), 7.29-7.31 (m, 1H), 7.35-7.39 (m, 2H); 13C NMR (CDCl3,
Me4Si) δ 14.59, 15.67, 15.93, 15.96, 17.39, 22.16, 22.31, 22.91, 23.51,
126.14, 127.98 (2C), 129.70 (2C), 132.00, 137.27, 137.77, 138.02,
139.09, 140.50, 142.85. Anal. Calcd for C21H28: C, 89.94; H, 10.06.
Found: C, 90.03; H, 10.16. 6a: 1H NMR (CDCl3, Me4Si) δ 1.08 (t, J
) 7.5 Hz, 3H), 1.15-1.20 (m, 9H), 2.57-2.64 (m, 4H), 2.67-2.70
(m, 4H), 3.99 (s, 2H), 6.79 (s, 1H), 7.12-7.18 (m, 3H), 7.24-7.27
(m, 2H); 13C NMR (CDCl3, Me4Si) δ 15.25, 15.59 (2C), 15.97, 21.76,
21.98, 22.18, 25.56, 39.18, 125.69, 128.24 (2C), 128.72 (2C), 128.75
(2C), 135.83, 138.09, 138.12, 140.18, 141.59.
5,6,7,8-Tetrahydro-2-pentyl-1,4-diethylnaphthalene (5b) and 5,6,7,8-
tetrahydro-2-hexyl-1,4-diethylnaphthalene (6b): A 1:1 mixture of
5b and 6b. Colorless liquid. Combined isolated yield: 62%. 5b: 1H
NMR (CDCl3, Me4Si) δ 0.92 (t, J ) 7.1 Hz, 3H), 1.09-1.15 (m, 6H),
1.38-1.48 (m, 6H), 1.75-1.78 (m, 4H), 2.26 (s, 3H), 2.56-2.66 (m,
6H), 2.71-2.75 (m, 4H); 13C NMR (CDCl3, Me4Si) δ 13.45, 14.09,
14.59, 15.07, 21.93, 22.36, 22.53, 23.29, 23.31, 27.11, 27.20, 30.00,
30.38, 32.69, 131.38, 132.63, 132.66, 136.73, 137.70, 138.51. 6b: 1H
NMR (CDCl3, Me4Si) δ 0.90 (t, J ) 6.8 Hz, 3H), 1.12 (t, J ) 7.3 Hz,
3H), 1.20 (t, J ) 7.5 Hz, 3H), 1.30-1.34 (m, 4H), 1.37-1.42 (m, 2H),
1.53-1.61 (m, 2H), 1.75-1.78 (m, 4H), 2.52-2.58 (m, 4H), 2.61 (q,
J ) 7.5 Hz, 2H), 2.67-2.70 (m, 2H), 2.74-2.77 (m, 2H), 6.85 (s,
1H); 13C NMR (CDCl3, Me4Si) δ 14.12, 14.28, 14.42, 21.26, 22.69,
22.93, 23.30, 25.50, 26.49, 26.97, 29.76, 31.82, 32.04, 33.06, 126.42,
132.62, 134.95, 137.47, 137.65, 139.36; HRMS calcd for C20H32
272.2502, found 272.2498.
X-ray Crystallographic Analysis of 1,2-dipropyl-3-tert-butyl-5,6-
diphenylbenzene (4i). A single crystal of approximate dimensions of
0.24 × 0.26 × 0.40 mm3 was cut out from the large crystal, placed on
a glass fiber with epoxy resin, and mounted on an Enraf-Nonius CAD4
diffractometer. The cell parameters were obtained from the least-squares
refinement of the setting angles of 25 carefully centered reflections.
Crystallographic data: fw ) 370.58, monoclinic, space group P21/n
(No. 14), Z ) 4, a ) 10.125(2) Å, b ) 24.829(2) Å, c ) 10.138(2) Å,
â ) 114.56(2)°, V ) 2318.0(8) Å3, Dx ) 1.06 g cm-3, and µ(Cu KR)
) 4.1 cm-1. The diffraction data were collected at room temperature
by using graphite-monochromated Cu KR radiation (λ ) 1.54184 Å).
A total of 4984 reflections (2Θ ) 148.52°) were measured, of which
3658 reflections were unique with |Fo| > 3σ(|Fo|). The structure was
solved by direct methods (SHELX-86)15 and subsequently completed
by Fourier recycling. All of the non-hydrogen atoms were refined
anisotropically by full-matrix least-squares techniques using the Xtal
3.216 crystallographic software package. All of the hydrogen atoms were
located at the calculated positions with isototropic displacement
parameters of their parent carbon atoms. Refinement of positional and
thermal parameters converged at R ) 0.053, Rw ) 0.068, and GOF )
2.66.
1
3H), 1.05 (t, J ) 7.5 Hz, 3H), 1.14 (t, J ) 7.4 Hz, 3H), 1.21 (t, J )
7.4 Hz, 3H), 1.49-1.53 (m, 4H), 2.27 (s, 3H), 2.51-2.63 (m, 8H),
6.84 (s, 1H); 13C NMR (CDCl3, Me4Si) δ 14.93, 15.01, 15.63, 15.74,
19.83, 21.83, 23.68, 25.10, 25.57, 31.78, 32.14, 128.46, 133.59, 136.98,
137.56, 138.63, 139.21; HRMS calcd for C17H28 232.2190; found
232.2190.
1-Methyl-2,3-diethyl-4,5-dipropylbenzene (4 g): Colorless oil.
1
Isolated yield: 50%. H NMR (CDCl3, Me4Si) δ 1.00 (t, J ) 7.3 Hz,
3H), 1.04 (t, J ) 7.4 Hz, 3H), 1.13 (t, J ) 7.5 Hz, 3H), 1.16 (t, J )
7.5 Hz, 3H), 1.46-1.53 (m, 2H), 1.56-1.63 (m, 2H), 2.27 (s, 3H),
2.49-2.57 (m, 4H), 2.63 (q, J ) 7.5 Hz, 2H), 2.65 (q, J ) 7.5 Hz,
2H), 6.83 (s, 1H); 13C NMR (CDCl3, Me4Si) δ 14.55, 14.58, 14.95,
15.94, 19.66, 22.14, 22.44, 24.77, 24.87, 31.39, 35.20, 129.20, 133.31,
136.33, 137.99, 138.15, 139.89; HRMS calcd for C17H28 232.2190;
found 232.2191.
1,2-Dipropyl-4-tert-butyl-5,6-diphenylbenzene (4h) and 1,2-
Dipropyl-3-tert-butyl-5,6-diphenylbenzene (4i). Column chromatog-
raphy afforded 4h as a colorless liquid (23%), 4i as a colorless solid
(34%), and the mixture of 4h and 4i (10%). 4h: 1H NMR (CDCl3,
Me4Si) δ 0.62 (t, J ) 7.3 Hz, 3H), 1.03 (t, J ) 7.3 Hz, 3H), 1.12 (s,
9H), 1.24-1.28 (m, 2H), 1.66-1.71 (m, 2H), 2.17-2.21 (m, 2H), 2.60-
2.64 (m, 2H), 6.79-7.07 (m, 10H), 7.34 (s, 1H); 13C NMR (CDCl3,
Me4Si) δ 14.60, 14.73, 24.31, 24.79, 32.63, 32.87 (3C), 35.52, 36.46,
125.25, 125.52, 126.12 (2C), 126.66 (2C), 126.85, 130.54 (2C), 132.24
(2C), 136.21, 138.73, 139.00, 141.69, 142.68, 143.46, 144.58. 4i: 1H
NMR (CDCl3, Me4Si) δ 0.78 (t, J ) 7.4 Hz, 3H), 1.13 (t, J ) 7.4 Hz,
3H), 1.33-1.38 (m, 2H), 1.54 (s, 9H), 1.68-1.74 (m, 2H), 2.55-2.59
(m, 2H), 2.92-2.96 (m, 2H), 7.07-7.19 (m, 10H), 7.33 (s, 1H); 13C
NMR (CDCl3, Me4Si) δ 14.84, 14.93, 24.83, 25.81, 32.36 (3C), 32.41,
33.43, 36.18, 125.56, 125.92, 126.00, 127.21 (2C), 127.28 (2C), 129.88
(2C), 130.87 (2C), 138.79, 138.96, 139.11, 141.15, 141.19, 143.01,
146.52. Anal. Calcd for C28H34: C, 90.75; H, 9.25. Found: C, 90.86;
H, 9.45.
Ethyl 2,4-dimethyl-3-trimethylsilyl-5,6-diethylbenzene carboxy-
late (4j) and ethyl 2,5-dimethyl-3,4-diethyl-6-trimethysilylbenzene
carboxylate (4k). A 1:1 mixture of 4j and 4k. Colorless liquid.
Combined GC yield: 50%. Isolated yield 43%. One isomer: 1H NMR
(CDCl3, Me4Si) δ 0.27 (s, 9H), 1.00-1.20 (m, 6H), 1.25-1.40 (m,
3H), 2.15 (s, 3H), 2.37 (s, 3H), 2.45-2.70 (m, 4H), 4.20-4.35 (m,
2H); 13C NMR δ 1.69 (3C), 14.17, 14.31, 15.68, 15.91, 16.30, 21.67,
22.55, 23.97, 60.71, 129.27, 132.07, 133.84, 137.85, 138.71, 141.20.
The other isomer: 1H NMR (CDCl3, Me4Si) δ 0.34 (s, 9H), 1.00-
1.20 (m, 6H), 1.25-1.40 (m, 3H), 2.27 (s, 3H), 2.35 (s, 3H), 2.45-
2.70 (m, 4H), 4.20-4.35 (m, 2H); 13C NMR δ 4.00 (3C), 14.20, 14.39,
15.75, 16.02, 20.80, 22.37, 22.60,24.21, 60.68, 129.30, 133.80, 136.73,
137.87, 138.77, 141.44; HRMS calcd for C18H30O2Si 306.2015; found
306.2017.
Reaction of Tetraphenylzirconacyclopentadiene with NiCl2-
(dppe). Formation of Tetraphenylnickelacyclopentadiene and
Cp2ZrCl2. To a solution of tetraphenylzirconacyclopentadiene 1b (2.0
mmol) in 20 mL THF was added NiCl2(dppe) (2.0 mmol, 1.06 g). The
mixture was refluxed under N2 for 24 h, and a brick-red solid
precipitated along with the formation of Cp2ZrCl2 in 94% NMR yield.
After filtration the solid was washed several times with dry diethyl
ether until the color of the filtrate disappeared. The brick-red solid 10b
was dried under vacuo to give the product in 78% (1.26 g) yield. IR
Ethyl 2-phenyl-3-trimethylsilyl-4-methyl-5,6-dipropylbenzene cor-
boxylate (4l) and ethyl 2-phenyl-3,4-dipropyl-5-methyl-6-trimeth-
ylsilylbenzene carboxylate (4m): A 1:1 mixture of 4l and 4m.
Colorless liquid. Combined GC yield: 45%. Isolated yield 40%. One
isomer: 1H NMR (CDCl3, Me4Si) δ -0.01 (s, 9H), 0.48(t, J ) 7.1
Hz, 3H), 0.53(t, J ) 7.1 Hz, 3H), 0.70-0.80(m, 4H), 1.16-1.30(m,
4H), 2.15(s, 3H), 2.18-2.31(m, 4H), 3.35(q, J ) 7.2 Hz, 2H), 6.85-
6.99(m, 5H); 13C NMR δ 1.97 (3C), 13.29, 14.70, 14.82, 21.11, 23.34,
24.36, 24.84, 32.80, 60.36, 127.28(2C), 130.01, 130.09(2C), 136.82,
137.01, 139.98, 140.18, 140.44, 141.92, 142.41, 170.87. The other
isomer: 1H NMR (CDCl3, Me4Si) δ -0.43(s, 9H), 0.34-0.39(m, 6H),
0.60-0.70(m, 4H), 0.93-1.0(m, 4H), 1.16-1.30(m, 2H), 1.95-2.00-
ν
Ni-C)C 1585 cm-1; MS m/z 813. The hydrolysis of this brick-red solid
10b by acetic acid resulted in the formation of 1,2,3,4-tetraphenyl-1,3-
butadiene in quantitative GC yield.
Reaction of Tetraphenylnickelacyclopentadiene 10b with 4-Oc-
tyne. Formation of 1,2-Dipropyl-3,4,5,6-tetraphenylbenzene. To a
mixture of 20 mL of toluene and 10b prepared from 1.0 mmol of NiCl2-
(dppe) as described above was added 4-octyne (4.0 mmol, 0.58 mL).
After refluxing in toluene for 12 h, the resulting mixture was diluted
with 100 mL of a 1/1 (v/v) mixture of benzene and hexane and then
(m, 2H), 2.14(s, 3H), 3.50(q, J ) 7.1 Hz, 2H), 6.85-6.99(m, 5H); 13
C
NMR δ 2.52(3C), 13.63, 14.97, 15.07, 21.59, 23.28, 31.68, 32.16, 33.62,
60.36, 126.72(2C), 127.15, 130.49(2C), 132.19, 133.55, 134.20, 136.24,
138.31, 138.80, 143.93, 170.57; HRMS calcd for C25H36O2Si 396.2483,
found 396.2489.
1-Phenyl-2,3,4,5-tetraethyl-6-methylbenzene (5a) and 1-benzyl-
2,3,4,5-tetraethylbenzene (6a): A 2.5:1 mixture of 5a and 6a. Colorless
liquid. Combined isolated yield: 53%. 5a: 1H NMR (CDCl3, Me4Si)
δ 0.90 (t, J ) 7.3 Hz, 3H), 1.18 (t, J ) 7.6 Hz, 3H), 1.22 (t, J ) 7.5
Hz, 3H), 1.25 (t, J ) 7.4 Hz, 3H), 1.89 (s, 3H), 2.36 (q, J ) 7.5 Hz,
(15) Sheldrick, G. M. SHELXS-86, Program for Crystal Structure
Determination; University of Gottingen: Germany, 1986.
(16) Hall, S. R.; Flack, H. D.; Stewart, J. M. Xtal 3.2, Program for X-ray
Crystal Structure Analysis; Universities of Western Australia, Geneva, and
Maryland, 1992.

11100 J. Am. Chem. Soc., Vol. 121, No. 48, 1999
Takahashi et al.
filtrated. Evaporation and column chromatography on silica gel
(benzene/hexane ) 1/3) afforded the product as a white solid in 54%
yield. 1H NMR (CDCl3, Me4Si) δ 0.75 (t, J ) 7.2 Hz, 6H), 1.43-1.49
(m, 4H), 2.49-2.53 (m, 4H), 6.71-6.75 (m, 10H), 7.04-7.22 (m, 10H);
13C NMR (CDCl3, Me4Si) δ 14.86, 24.67, 33.16, 124.81, 125.75,
126.26, 127.04, 130.59, 131.19, 138.28, 138.79, 140.94, 140.96, 141.27;
HRMS calcd for C36H34 466.2661; found 466.2675.
supported by the Ministry of Education, Science, Sport and
Culture, Japan (09440212).
Supporting Information Available: Tables of crystal-
lographic data, atomic coordinates, thermal parameters and bond
lengths and angles for 4i (PDF). This material is available free
of charge via the Internet at http://pubs.acs.org.
Acknowledgment. We thank the Inoue Foundation for an
Inoue fellowship to support F.-Y. Tsai. A part of this work was
JA990750C