Ruthenium-catalyzed allylic substitution of cyclic allyl carbonates with nucleophiles. Stereoselectivity and scope of the reaction

Article abstract of DOI:10.1021/om990533k

CpRuCl(cod)/NH₄PF₆ (Cp = cyclopentadienyl, cod = 1,5-cyclooctadiene) is an effective catalyst system for the allylic substitution of cyclic allyl carbonates with nucleophiles. This catalyst system enables the first investigation of t

Full text of DOI:10.1021/om990533k

4742
Organometallics 1999, 18, 4742-4746
Ru th en iu m -Ca ta lyzed Allylic Su bstitu tion of Cyclic Allyl
Ca r bon a tes w ith Nu cleop h iles. Ster eoselectivity a n d
Scop e of th e Rea ction
Yasuhiro Morisaki, Teruyuki Kondo,* and Take-aki Mitsudo*
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering,
Kyoto University, Sakyo-ku, Kyoto 606-8501, J apan
Received J uly 12, 1999
CpRuCl(cod)/NH4PF6 (Cp ) cyclopentadienyl, cod ) 1,5-cyclooctadiene) is an effective
catalyst system for the allylic substitution of cyclic allyl carbonates with nucleophiles. This
catalyst system enables the first investigation of the stereochemical course of the ruthenium-
catalyzed allylic substitution reaction, in which the reaction proceeds with an overall
retention of configuration. The stoichiometric reaction of trans-5-(methoxycarbonyl)cyclohex-
2-enyl chloride with Cp*RuCl(cod) (Cp* ) pentamethylcyclopentadienyl) gave the unexpected
complex Cp*Ru(η6-C6H5CO2Me)+ by the rapid dehydrohalogenation/dehydrogenation of the
desired Cp*RuCl2(η3-C6H8CO2Me) complex.
In tr od u ction
lective allylic substitution of acyclic allyl carbonates
with carbon5 and nitrogen nucleophiles,6 in which
substitution exclusively occurred at the more-substi-
tuted allylic terminus in η3-allylruthenium intermedi-
ates. Essential to the use of this process in organic
synthesis is control of the stereochemical course of the
reaction, as well as the regiochemistry. Although ru-
thenium complexes often show interesting catalytic
activity and product selectivity, which are quite different
from those with palladium and other transition-metal
complexes,7 the appropriate matching and tuning of the
ruthenium catalysts with the substrates, ligands, and
solvents used are always important.6,8 For example,
catalysts such as Ru(cod)(cot)5 (cod ) 1,5-cyclooctadiene,
cot ) 1,3,5-cyclooctatriene) and Cp*RuCl(cod)6 (Cp* )
pentamethylcyclopentadienyl), which were highly active
for the allylic substitution of acyclic allyl carbonates,
were totally ineffective for the allylic substitution of
cyclic allyl carbonates. Thus, we have been continuing
our efforts to improve and modify the ruthenium
catalyst system. After many trials, we finally found that
CpRuCl(cod)/NH4PF6 (Cp ) cyclopentadienyl) is a highly
effective catalyst system for the allylic substitution of
cyclic allyl carbonates (eq 1). We report here the
The transition-metal-complex-catalyzed substitution
reaction of allylic alcohol derivatives with nucleophilic
reagents is now a well-established methodology in
organic synthesis and is widely used to construct
complex organic molecules.1 Most of the work in this
field has been devoted to palladium complexes for the
design of chemo-, regio-, stereo-, and enantioselective
catalyst systems,2 and a wide range of transition-metal
complexes has recently been used for the reaction.3
However, a general use of ruthenium catalysts has not
been forthcoming,4 and examples are strictly limited to
our reports on the ruthenium-catalyzed highly regiose-
(1) (a) Harrington, P. J . In Transition Metals in Total Synthesis;
Wiley: New York, 1990; p 25. (b) Godleski, S. A. In Comprehensive
Organic Synthesis; Trost, B. M., Ed.; Pergamon: Oxford, U.K., 1991;
Vol. 4, p 585. (c) Hegedus, L. S. In Transition Metals in the Synthesis
of Complex Organic Molecules; University Science Books: Mill Valley,
CA, 1994; p 261. (d) Tsuji, J . In Palladium Reagents and Catalysts;
Wiley: New York, 1995; p 290. (e) Harrington, P. J . In Comprehensive
Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson,
G., Eds.; Pergamon: Oxford, U.K., 1995; Vol. 12, p 797. (f) Heumann,
A. In Transition Metals for Organic Synthesis; Beller, M., Bolm, C.,
Eds.; Wiley-VCH: New York, 1998; Vol. 1, p 251. For a review, see:
(g) Trost, B. M. Tetrahedron 1977, 33, 2615. (h) Trost, B. M. Acc. Chem.
Res. 1980, 13, 385. (i) Tsuji, J . Pure Appl. Chem. 1982, 54, 197. (j)
Tsuji, J .; Minami, I. Acc. Chem. Res. 1987, 20, 140.
(2) (a) Trost, B. M. Pure Appl. Chem. 1981, 53, 2357. (b) Ba¨ckvall,
J .-E. Acc. Chem. Res. 1983, 16, 335. (c) Ba¨ckvall, J .-E. Pure Appl. Chem.
1983, 55, 1669. (d) Tsuji, J . Tetrahedron 1986, 42, 4361. (e) Trost, B.
M. Angew. Chem., Int. Ed. Engl. 1989, 28, 1173. (f) Consiglio, G.;
Waymouth, R. Chem. Rev. 1989, 89, 257. (g) Frost, C. G.; Howarth, J .;
Williams, J . M. J . Tetrahedron: Asymmetry 1992, 3, 1089. (h) Trost,
B. M. Pure Appl. Chem. 1996, 68, 779. (i) Trost, B. M.; Van Vranken,
D. L. Chem. Rev. 1996, 96, 395. (j) J ohannsen, M.; J ørgensen, K. A.
Chem. Rev. 1998, 98, 1689.
(3) For lead references, see the following. (a) Fe: Enders, D.;
J andeleit, B.; Raabe, G. Angew. Chem., Int. Ed. Engl. 1994, 33, 1949.
(b) Co: Bhatia, B.; Reddy, M. M.; Iqbal, J . Tetrahedron Lett. 1993, 34,
6301. (c) Ni: Bricout, H.; Carpentier, J .-F.; Mortreux, A. J . Chem. Soc.,
Chem. Commun. 1995, 1863. (d) Rh: Evans, P. A.; Nelson, J . D. J .
Am. Chem. Soc. 1998, 120, 5581. (e) Ir: Takeuchi, R.; Kashio, M. J .
Am. Chem. Soc. 1998, 120, 8647. (f) Pt: Brown, J . M.; MacIntyre, J .
E. J . Chem. Soc., Perkin Trans. 2 1985, 961. (g) Mo: Trost, B. M.;
Hachiya, I. J . Am. Chem. Soc. 1998, 120, 1104. (h) W: Lloyd-J ones,
G. C.; Pfaltz, A. Angew. Chem., Int. Ed. Engl. 1995, 34, 462 and
pertinent references therein.
development of this new catalyst system, which has
enabled the first investigation of the stereochemical
course of the ruthenium-catalyzed allylic substitution
reaction.
(4) The catalytic activity of RuH2(PPh3)4 for the allylic alkylation
reaction has been reported briefly: Minami, I.; Shimizu, I, Tsuji, J . J .
Organomet. Chem. 1985, 296, 269.
(5) Zhang, S.-W.; Mitsudo, T.; Kondo, T.; Watanabe, Y. J . Orga-
nomet. Chem. 1993, 450, 197.
(6) Kondo, T.; Ono, H.; Satake, N.; Mitsudo, T.; Watanabe, Y.
Organometallics 1995, 14, 1945.
10.1021/om990533k CCC: $18.00 © 1999 American Chemical Society
Publication on Web 10/13/1999

Ru-Catalyzed Substitution of Cyclic Allyl Carbonates
Organometallics, Vol. 18, No. 23, 1999 4743
Ta ble 1. Effects of th e Ca ta lyst a n d th e Solven t on
th e Syn th esis of 3a by th e Rea ction of 1a w ith 2a a
Ta ble 2. Cp Ru Cl(cod )/NH4P F 6-Ca ta lyzed Allylic
Su bstitu tion of Cyclic Allyl Ca r bon a tes w ith
Nu cleop h ilesa
catalyst
additiveb
solvent
yield (%)c
Ru(cod)(cot)
Ru3(CO)12
decane
decane
4
0
RuH2(PPh3)4
RuCl2(PPh3)3
Cp*RuCl(cod)
CpRuCl(cod)
CpRuCl(cod)
CpRuCl(cod)
CpRuCl(cod)
CpRuCl(cod)
CpRuCl(PPh3)2
decane
decane
decane
decane
8
10
0
27
86
75
18
15
55
NH4PF6
NH4PF6
NH4PF6
NH4PF6
NH4PF6
decane
N-methylpiperidine
1,4-dioxane
mesitylene
decane
a
A mixture of 1a (1.0 mmol), 2a (2.0 mmol), Ru complex (0.050
mmol), and solvent (2.0 mL) in a 20-mL Pyrex flask was heated
b
at 100 oC for 24 h under an argon atmosphere. NH4PF6 (0.10
mmol) was used. c GLC yield based on the amount of 1a charged.
Resu lts a n d Discu ssion
We initially examined the catalytic activity of several
ruthenium complexes in the reaction of cyclohex-2-enyl
methyl carbonate (1a ) with piperidine (2a ), and the
results are summarized in Table 1. The reaction of 1a
(1.0 mmol) with 2a (2.0 mmol) in the presence of a
catalytic amount of CpRuCl(cod) (5 mol %) and NH4-
PF6 (10 mol %) in decane (2.0 mL) at 100 °C for 24 h
under an argon atmosphere gave the corresponding
cyclic allylamine, N-(cyclohex-2-enyl)piperidine (3a ), in
86% yield. Other ruthenium catalysts, such as Ru(cod)-
(cot),5 Ru3(CO)12, RuH2(PPh3)4,4 RuCl2(PPh3)3, and
Cp*RuCl(cod),6 were totally ineffective in the present
reaction. Although the catalytic activity of CpRuCl(cod)
itself was low, the concomitant use of NH4PF6 dramati-
cally increased the catalytic activity, probably due to
the formation of a coordinatively unsaturated cationic
ruthenium species,9 which is needed to overcome the
steric hindrance of cyclic allyl carbonates. The PPh3
ligand showed a negative effect in the reaction using
the catalyst system of CpRuCl(PPh3)2/NH4PF6. The
present reaction was also affected by the solvent, and
the yield of 3a drastically decreased in mesitylene and
1,4-dioxane. The best result was obtained in decane.
The results obtained from the CpRuCl(cod)/NH4PF6-
catalyzed allylic substitution of several cyclic allyl
carbonates with nucleophiles are summarized in Table
2. Both acyclic primary and secondary amines, repre-
sented by benzylamine (2b) and dipropylamine (2c),
were smoothly allylated with 1a to give the correspond-
ing cyclic allylamines, 3b and 3c, in high isolated yields.
Five-membered and seven-membered cyclic allyl car-
bonates, 1b and 1c, also reacted with 2a to give the
corresponding cyclic allylamines, 3d and 3e, in good
yields. In the case of 1d , substitution predominantly
a
Conditions: cyclic allylic carbonate (1.0 mmol), nucleophile (2.0
mmol), CpRuCl(cod) (0.050 mmol), NH4PF6 (0.10 mmol), decane
b
(2.0 mL) at 100 °C for 24 h under an argon atmosphere. Based
on the amount of allyl carbonate charged. c 3f/3f′ ) 77:23.
occurred at the less-substituted allylic carbon to give a
mixture of regioisomers, 3f and 3f′, in a total isolated
yield of 88% with a ratio of 77:23. The regiochemistry
is quite different from that observed in our previous
study on acyclic allyl carbonates,5,6 probably due to the
higher steric hindrance of 1d and relatively severe
reaction conditions. Allylic alkylation of a stabilized
C-nucleophile, dimethyl sodiomalonate (4a ), with 1a
also proceeded smoothly to give 5a in an isolated yield
of 92%.
The development of this new catalyst system enables
the first investigation of the stereochemical course of
the ruthenium-catalyzed allylic substitution reaction.
First, we chose cis-5-(methoxycarbonyl)cyclohex-2-enyl
methyl carbonate (cis-1e) as a substrate because it has
been extensively used to examine the stereochemical
course of palladium-10 and molybdenum-catalyzed11
allylic substitution reactions. Treatment of cis-1e with
piperidine (2a ) in the presence of 5 mol % CpRuCl(cod)
(7) For a recent example, see: (a) Kondo, T.; Suzuki, N.; Okada, T.;
Mitsudo, T. J . Am. Chem. Soc. 1997, 119, 6187. (b) Suzuki, N.; Kondo,
T.; Mitsudo, T. Organometallics 1998, 17, 766. (c) Kondo, T.; Ue-
noyama, S.; Fujita, K.; Mitsudo, T. J . Am. Chem. Soc. 1999, 121, 482.
(d) Mitsudo, T.; Suzuki, T.; Zhang, S.-W.; Imai, D.; Fujita, K.; Manabe,
T.; Shiotsuki, M.; Watanabe, Y.; Wada, K.; Kondo, T. J . Am. Chem.
Soc. 1999, 121, 1839 and references therein. For a review, see: Naota,
T.; Takaya, H.; Murahashi, S. Chem. Rev. 1998, 98, 2599.
(8) For example, see: (a) Kondo, T.; Hiraishi, N.; Morisaki, Y.; Wada,
K.; Watanabe, Y.; Mitsudo, T. Organometallics 1998, 17, 2131. (b)
Kondo, T.; Kodoi, K.; Nishinaga, E.; Okada, T.; Morisaki, Y.; Watanabe,
Y.; Mitsudo, T. J . Am. Chem. Soc. 1998, 120, 5587.
(10) (a) Trost, B. M.; Verhoeven, T. R. J . Am. Chem. Soc. 1980, 102,
4730. (b) Granberg, K. L.; Ba¨ckvall, J .-E. J . Am. Chem. Soc. 1992, 114,
6858.
(11) (a) Trost, B. M.; Lautens, M. J . Am. Chem. Soc. 1987, 109, 1469.
(b) Trost, B. M.; Merlic, C. A. J . Am. Chem. Soc. 1990, 112, 9590.
(9) (a) Davies, S. D.; McNally, J . P.; Smallridge, A. J . Adv. Orga-
nomet. Chem. 1990, 30, 1. (b) For catalytic reactions, see: Trost, B.
M. Chem. Ber. 1996, 129, 1313 and references therein.

4744 Organometallics, Vol. 18, No. 23, 1999
Morisaki et al.
and 10 mol % NH4PF6 in decane at 100 °C for 20 h
predominantly gave cis-3g (total yield of 3g 67%, cis-
3g:trans-3g ) 95:5) (eq 2).12 The reactivity of trans-5-
(methoxycarbonyl)cyclohex-2-enyl methyl carbonate
(trans-1e) was higher than that of cis-1e, and the
reaction of trans-1e with 2a at 50 °C for 6 h gave trans-
3g almost exclusively (total yield of 3g 98%, trans-3g:
cis-3g ) 98:2) (eq 3). The selective formation of trans-
exchanged complex [Cp*Ru(η6-C6H5CO2Me)]+[BPh4]-
(8) (Figure 1).15 A similar reaction sequence has already
been reported in the reaction of CpRuBr(cod) with
3-bromocyclohexene by Singleton and co-workers.16
Thus, our attempt to determine the stereochemistry of
the oxidative addition of allylic compounds to ruthenium
was in vain.
Although little work has been done to determine the
stereochemical course of the reaction of (η3-allyl)ruthe-
nium complexes with nucleophiles, Harman and co-
workers recently reported that the reaction with soft
nucleophiles exclusively proceeded via an anti mecha-
nism,17 as in the reaction of most (η3-allyl)palladium
complexes.10,18 The observations described here together
with information in the literature allow us to suggest
that the ruthenium-catalyzed allylic substitution reac-
tion proceeds via a double-inversion (anti-anti) mech-
anism.19,20 The higher reactivity of trans-1e compared
to that of cis-1e in the present reaction was explained
5b from the reaction of trans-1e with a stabilized
C-nucleophile (4a ) was also observed (total yield of 5b
99%, trans-5b:cis-5b ) 97:3), where the addition of NH4-
PF6 as a cocatalyst was not needed (eq 4). Consequently,
the ruthenium-catalyzed allylic substitution proceeded
with an overall retention of configuration, since inter-
conversion of cis-3g and trans-3g was not observed in
any of these reactions.
(15) Crystal data for 8: C42H43O2BRu, mol wt ) 691.68, yellow
crystals, prismatic (0.10 × 0.10 × 0.20 mm), orthorhombic, space group
P212121 (No. 19), a ) 14.82(1) Å, b ) 14.96(1) Å, c ) 31.85(1) Å, V )
7061(7) Å3, Z ) 8, Dcalcd ) 2.602 g/cm3, F000 ) 5760.00, µ(Mo KR) )
9.57 cm-1, data collection temperature 23.0 °C, scan type ω (8.0°/min),
2θmax ) 55.0°, 8864 reflections measured, 4708 reflections observed (I
> 3.00σ(I)), R ) 0.056, Rw ) 0.060, GOF ) 1.04.
(16) (a) Albers, M. O.; Liles, D. C.; Robinson, D. J .; Shaver, A.;
Singleton, E. J . Chem. Soc., Chem. Commun. 1986, 645. (b) Albers,
M. O.; Liles, D. C.; Robinson, D. J .; Shaver, A.; Singleton, E. Organo-
metallics 1987, 6, 2347.
(17) Spera, M. L.; Chin, R. M.; Winemiller, M. D.; Lopez, K. W.;
Sabat, M.; Harman, W. D. Organometallics 1996, 15, 5447.
(18) (a) Trost, B. M.; Weber, L. J . Am. Chem. Soc. 1975, 97, 1611.
(b) Trost, B. M.; Weber, L.; Strege, P. E.; Fullerton, T. J .; Dietsche, T.
J . J . Am. Chem. Soc. 1978, 100, 3416. (c) Trost, B. M.; Verhoeven, T.
R. J . Am. Chem. Soc. 1978, 100, 3435. (d) Collins, D. J .; J ackson, W.
R.; Timms, R. N. Aust. J . Chem. 1977, 30, 2167. (e) A° kermark, B.;
Ba¨ckvall, J .-E.; Lo¨wenborg, A.; Zetterberg, K. J . Organomet. Chem.
1979, 166, C33. (f) A° kermark, B.; J utand, A. J . Organomet. Chem.
1981, 217, C41.
(19) For a mechanism with double inversion of configuration in
palladium-catalyzed allylic alkylation reactions, see: (a) Hayashi, T.;
Hagihara, T.; Konishi, M.; Kumada, M. J . Am. Chem. Soc. 1983, 105,
7767. (b) Hayashi, T.; Konishi, M.; Kumada, M. J . Chem. Soc., Chem.
Commun. 1984, 107. (c) Hayashi, T.; Yamamoto, A.; Hagihara, T. J .
Org. Chem. 1986, 51, 723. (d) Fiaud, J .-C.; Legros, J .-Y. J . Org. Chem.
1987, 52, 1907.
To investigate the stereochemistry of the first oxida-
tive-addition step of allylic compounds to ruthenium, a
stoichiometric reaction of Cp*RuCl(cod) with trans-6a
was examined.13 The reaction proceeded smoothly in
ethanol at 50 °C for 5 h to give an unexpected [Cp*Ru-
(η6-C6H5CO2Me)]+Cl- complex (7) as the sole product,
which would be obtained by rapid dehydrohalogenation/
dehydrogenation14 of the desired Cp*RuCl2(η3-C6H8CO2-
Me) complex (eq 5). The molecular structure of 7 was
established by X-ray structure analysis of the anion-
(12) The effect of the concentration of CpRuCl(cod) catalyst (5, 10,
25, and 50 mol %) was also examined in the reaction of cis-1e with 2a .
The best stereoselectivity of product 3g was observed in eq 2 (5 mol %
CpRuCl(cod), cis-3g/trans-3g ) 95/5). While the increase of the
concentration of CpRuCl(cod) catalyst slightly decreased the stereo-
selectivity of 3g, the stereoselectivity was constant in the range from
10 mol % to 50 mol % CpRuCl(cod) catalyst (10 mol %, cis-3g/trans-3g
) 86/14; 25 mol %, cis-3g/trans-3g ) 88/12; 50 mol %, cis-3g/trans-3g
) 87/13). For a related reference, see: Ward, Y. D.; Villanueva, L. A.;
Allred, G. D.; Liebeskind, L. S. J . Am. Chem. Soc. 1996, 118, 897.
(13) Since no reaction occurred between Cp*RuCl(cod) and an allylic
carbonate, trans-1e, under the stoichiometric reaction conditions, the
reaction with a more reactive allylic halide, trans-6a , was examined.
(14) The formation of (η6-arene)ruthenium(II) complexes by dehy-
drogenation of cyclohexadienes with ruthenium(III) trichloride has
been reported: Bennet, M. A.; Smith, A. K. J . Chem. Soc., Dalton
Trans. 1974, 233.
(20) A mechanism with double retention of configuration is unlikely
in the present reaction, but cannot be completely ruled out: (a) Faller,
J . W.; Linebarrier, D. Organometallics 1988, 7, 1670. (b) Dvorˇa´k, D.;
Stary´, I.; Kocˇovsky´, P. J . Am. Chem. Soc. 1995, 117, 6130.

Ru-Catalyzed Substitution of Cyclic Allyl Carbonates
Organometallics, Vol. 18, No. 23, 1999 4745
PF6 and Ru3(CO)12 were obtained commercially and used
without further purification. Ru(cod)(cot),24 RuH2(PPh3)4,25
RuCl2(PPh3)3,26 Cp*RuCl(cod),27 CpRuCl(cod),28 and CpRuCl-
29
(PPh3)2 were prepared as described in the literature.
Gen er a l P r oced u r e. A mixture of cyclic allylic carbonate
(1) (1.0 mmol), N-nucleophile (2) or C-nucleophile (4a ) (2.0
mmol), CpRuCl(cod) (15.5 mg, 0.050 mmol), NH4PF6 (16.3 mg,
0.10 mmol), and decane (2.0 mL) was placed in a two-necked
20-mL Pyrex flask equipped with a magnetic stirring bar and
a reflux condenser under a flow of argon. The mixture was
magnetically stirred at 100 °C for 24 h. After the reaction
mixture was cooled, the products were analyzed by GLC and
isolated by column chromatography (Florisil (60-100 mesh),
eluent Et2O), followed by Kugelrohr distillation.
The spectral and analytical data of 3a ,30 3c,31 3d ,32 5a ,33
trans-5b,10 and cis-5b10 have already been reported. All of the
new compounds are characterized below.
3-Meth ylcycloh ex-2-en yl Meth yl Ca r bon a te (1d ). Color-
less liquid. Bp: 60-65 °C (1.0 mmHg, Kugelrohr). IR (neat):
1672, 1749 cm-1. 1H NMR (CDCl3, 270 MHz): δ 1.61-1.64 (m,
1H), 1.71 (s, 3H), 1.75-1.79 (m, 3H), 1.94-1.96 (m, 2H), 3.77
(s, 3H), 5.08 (br, 1H), 5.53 (br, 1H). 13C NMR (CDCl3, 67.5
MHz): δ 18.4, 23.3, 27.6, 29.6, 54.0, 72.2, 119.1, 141.3, 155.2.
MS (EI): m/z 170 (M+). Anal. Calcd for C9H14O3: C, 63.51; H,
8.29. Found: C, 63.75; H, 8.49.
F igu r e 1. ORTEP drawing of 8 with 30% thermal el-
lipsoids. Only one of the two independent molecules is
shown for clarity. Hydrogen atoms and the counterion
(BPh4-) are also omitted for clarity.
N-(Cycloh ex-2-en yl)d ip r op yla m in e (3b). Colorless liq-
uid. Bp: 50-55 °C (1.0 mmHg, Kugelrohr). IR (neat): 724,
as follows. trans-1e should always react faster, since the
leaving group is pseudoaxial, so that the alignment of
the π system with the σ* orbital is easily attained in
contrast to cis-1e, where the leaving group is pseu-
doequatorial.21
In conclusion, we developed a novel ruthenium cata-
lyst system for allylic substitution of cyclic allyl carbon-
ates. The development of this new catalyst system
provides some insight into the stereochemistry of the
ruthenium-catalyzed allylic substitution reaction, and
we believe that this finding broadens the applicability
of the ruthenium catalyst to organic synthesis using a
transition-metal-catalyzed allylic substitution reaction.
1656 cm-1 1H NMR (CDCl3, 300 MHz): δ 0.85 (t, 3H, J )
.
7.34 Hz), 1.26 (br, 2H), 1.42 (m, 4H), 1.76-1.80 (m, 2H), 1.95
(br, 2H), 2.27-2.46 (m, 4H), 3.34 (br, 1H), 5.59-5.62 (m, 1H),
5.70-5.80 (m, 1H). 13C NMR (CDCl3, 75 MHz): δ 11.9, 22.0,
22.4, 23.9, 25.4, 53.0, 57.1, 129.2, 131.3. MS (EI): m/z 181 (M+).
Anal. Calcd for C12H23N: C, 79.49; H, 12.78. Found: C, 79.36;
H, 12.88.
N-(Cycloh ep t-2-en yl)p ip er id in e (3e). Colorless liquid.
Bp: 60-70 °C (1.0 mmHg, Kugelrohr). IR (neat): 1650 cm-1
.
1H NMR (CDCl3, 300 MHz): δ 1.24-1.34 (m, 2H), 1.34-1.47
(m, 3H), 1.50-1.63 (m, 4H), 1.63-1.70 (m, 1H), 1.82-1.86 (m,
1H), 1.90-2.20 (m, 3H), 2.42-2.55 (m, 4H), 3.20 (br, 1H),
5.72-5.85 (m, 2H). 13C NMR (CDCl3, 75 MHz): δ 24.7, 26.4,
26.6, 28.3, 28.9, 29.2, 49.5, 65.4, 130.4, 135.1. MS (EI): m/z
179 (M+). Anal. Calcd for C12H21N: C, 80.38; H, 11.80. Found:
C, 80.10; H, 11.65.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. GLC analyses were performed
on a Shimadzu GC-8A gas chromatograph with a glass column
(3 mm i.d. × 3 m) packed with Silicone SE-30 (5% on
Chromosorb W(AW-DMCS), 80-100 mesh) and a Shimadzu
GC-14A gas chromatograph with a capillary column (Shi-
madzu capillary column HiCap-CBP10-M25-025 (polarity
N-(3-Meth ylcycloh ex-2-en yl)p ip er id in e (3f). Colorless
liquid. Bp: 60-70 °C (1.0 mmHg, Kugelrohr). IR (neat): 1687
cm-1. 1H NMR (CDCl3, 300 MHz): δ 1.35-1.50 (m, 2H), 1.50-
1.61 (m, 6H), 1.67 (s, 3H), 1.71-1.82 (m, 2H), 1.82-1.95 (m,
2H), 2.42-2.61 (m, 4H), 3.12 (m, 1H), 5.38 (br, 1H). 13C NMR
(CDCl3, 75 MHz): δ 22.4, 23.7, 24.8, 25.0, 26.5, 30.1, 49.7, 61.3,
124.3, 136.6. MS (EI): m/z 179 (M+). Exact mass: calcd for
1
similar to OV-1701): 0.22 mm i.d. × 25 m). The H (270, 300,
and 400 MHz) and 13C NMR spectra (67.5, 75, and 100 MHz)
were obtained on J EOL GSX-270, AL-300, and EX-400 spec-
trometers, respectively. Samples were analyzed in CDCl3, and
the chemical shift values are expressed relative to Me4Si as
an internal standard. IR spectra were obtained on a Nicolet
Impact 410 spectrometer. High-resolution mass spectra (HRMS)
were obtained on a J EOL J MS-SX102A mass spectrometer.
Elemental analyses were performed at the Microanalytical
Center of Kyoto University.
C
12H21N, 179.1675; found, 179.1673.
N-(1-Meth ylcycloh ex-2-en yl)p ip er id in e (3f′). Colorless
liquid. Bp: 60-70 °C (1.0 mmHg, Kugelrohr). IR (neat): 737,
1
1673 cm-1. H NMR (CDCl3, 300 MHz): δ 1.17 (s, 3H), 1.35-
1.50 (m, 2H), 1.50-1.61 (m, 6H), 1.71-1.82 (m, 2H), 1.82-
1.95 (m, 2H), 2.42-2.61 (m, 4H), 5.50 (d, J ) 10.28 Hz, 1H),
5.67 (dt, J ) 10.28, 3.76 Hz, 1H). 13C NMR (CDCl3, 75 MHz):
(24) Itoh, K.; Nagashima, H.; Oshima, T.; Oshima, N.; Nishiyama,
H. J . Organomet. Chem. 1984, 272, 179.
(25) Young, R.; Wilkinson, G. Inorg. Synth. 1977, 17, 75.
(26) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth.
1970, 12, 237.
(27) Oshima, N.; Suzuki, H.; Moro-oka, Y. Chem. Lett. 1984, 1161.
(28) Albers, M. O.; Robinson, J . D.; Shaver, A.; Singleton, E.
Organometallics 1986, 5, 2199.
(29) Bruce, M. I.; Windsor, N. J . Aust. J . Chem. 1977, 30, 1601.
(30) Tamura, R.; Kai, Y.; Kakihana, M.; Hayashi, K.; Tsuji, M.;
Nakamura, T.; Oda, D. J . Org. Chem. 1986, 51, 4375.
(31) Guy, A.; Barbetti, J . F. Synth. Commun. 1992, 22, 853.
(32) Khvostenko, V. I.; Galkin, E. G.; Dzhemilev, U. M.; Tolstikov,
G. A.; Yakupova, A. Z.; Rafikov, S. R. Dokl. Akad. Nauk SSSR 1977,
235, 417.
Ma ter ia ls. The reagents used in this study were dried and
purified before use by standard procedures. Cyclic allyl
carbonates (1a -e) were prepared from the corresponding
alcohols and methyl chloroformate according to the reported
procedure.22 cis- and trans-5-(Methoxycarbonyl)cyclohex-2-en-
1-ol and trans-5-(methoxycarbonyl)cyclohex-2-enyl chloride
(trans-6a ) were prepared as described in the literature.23 NH4-
(21) Farthing, C. N.; Kocˇovsky´, P. J . Am. Chem. Soc. 1998, 120,
6661.
(22) Tsuji, J .; Sato, K.; Okamoto, H. J . Org. Chem. 1984, 49, 1341.
(23) Ba¨ckvall, J .-E.; Granberg, K.; Heumann, A. Isr. J . Chem. 1991,
31, 17.
(33) Laidig, G. J .; Hegedus, L. S. Synthesis 1995, 5, 527.

4746 Organometallics, Vol. 18, No. 23, 1999
Morisaki et al.
δ 20.4, 21.9, 24.9, 25.5, 26.8, 28.0, 46.9, 56.7, 126.7, 135.5. MS
(EI): m/z 179 (M+). These spectral data were obtained for a
77:23 mixture of 3f and 3f′.
was recrystallized from CH2Cl2/Et2O to give 103.2 mg (0.15
mmol, 83%) of [Cp*Ru(η6-C6H5CO2Me)]+[BPh4]- (8) as orange
crystals. Mp: 175.6-179.0 °C dec. IR (KBr): 1730 cm-1 1H
.
Meth yl cis-5-P iper idin ylcycloh ex-3-en ecar boxylate (cis-
3g). Colorless liquid. Bp: 100-110 °C (1.0 mmHg, Kugelrohr).
NMR (270 MHz, CD2Cl2): δ 1.83 (s, 15H), 3.96 (s, 3H), 5.49-
5.54 (m, 3H), 6.14 (d, J ) 6.24 Hz, 2H), 6.87 (t, J ) 7.16 Hz,
4H), 7.02 (t, J ) 7.43 Hz, 8H), 7.31 (m, 8 H). 13C NMR (CDCl3,
67.5 MHz): δ 10.5, 53.9, 87.1, 87.9, 88.6, 98.4, 122.2, 125.9,
126.0, 136.3, 163.3, 164.0, 164.6, 164.7, 165.4.
IR (neat): 1736 cm-1 1H NMR (CDCl3, 400 MHz): δ 1.41-
.
1.46 (m, 2H), 1.54-1.60 (m, 4H), 1.63 (q, J ) 7.81 Hz, 1H),
2.08-2.11 (m, 1H), 2.19-2.23 (m, 2H), 2.47-2.50 (m, 2H),
2.54-2.62 (m, 3H), 3.36 (m, 1H), 3.70 (s, 3H), 5.66-5.69 (m,
1H), 5.75-5.77 (m, 1H). 13C NMR (CDCl3, 100 MHz): δ 24.7,
25.0, 26.5, 27.9, 39.4, 49.5, 51.7, 61.3, 127.1, 130.6, 175.9. MS
(EI): m/z 223 (M+). Anal. Calcd for C13H21NO2: C, 69.92; H,
9.48. Found: C, 69.87; H, 9.26.
Meth yl tr a n s-5-P ip er id in ylcycloh ex-3-en eca r boxyla te
(tr a n s-3g). Colorless liquid. Bp: 100-110 °C (1.0 mmHg,
Kugelrohr). IR (neat): 1736 cm-1. 1H NMR (CDCl3, 400 MHz);
δ 1.41-1.46 (m, 2H), 1.51-1.62 (m, 4H), 1.76 (ddd, J ) 5.86,
9.72, 13.67 Hz, 1H), 2.06 (td, J ) 4.40, 13.67 Hz, 1H), 2.22-
2.26 (m, 2H), 2.43-2.50 (m, 2H), 2.54-2.61 (m, 2H), 2.72-
2.79 (m, 1H), 3.13-3.14 (m, 1H), 3.69 (s, 3H), 5.68-5.75 (m,
1H), 5.82-5.87 (m, 1H). 13C NMR (CDCl3, 100 MHz): δ 24.6,
25.0, 26.4, 27.1, 36.9, 49.2, 50.5, 57.5, 127.5, 128.4, 175.6. MS
(EI): m/z 223 (M+). Anal. Calcd for C13H21NO2: C, 69.92; H,
9.48. Found: C, 69.85; H, 9.21.
X-r a y Str u ctu r a l Deter m in a tion of [Cp *Ru (η6-
C6H5CO2Me)]+[BP h 4]- (8). Crystal data, data collection, and
refinement parameters for [Cp*Ru(η6-C6H5CO2Me)]+[BPh4]-
(8) are summarized in the X-ray structure report (see the
Supporting Information). A single crystal of [Cp*Ru(η6-C6H5-
CO2Me)]+[BPh4]- (8) was mounted and placed on a Rigaku
AFC-7R diffractometer. The unit cell was determined by the
automatic indexing of 20 centered reflections and confirmed
by the examination of axial photographs. Intensity data were
collected using graphite-monochromated Mo KR X-radiation
(λ ) 0.710 69 Å). Check reflections were measured every 150
reflections; the data were scaled accordingly and corrected for
Lorentz, polarization, and absorption effects. The structure
was determined using Patterson and standard difference map
techniques on an O2 computer using SHELX97.34 Systematic
absences were uniquely consistent with the space group
P212121 (No. 19).
P r ep a r a tion of [Cp *Ru (η6-C6H5CO2Me)]+[Cl]- (7) a n d
[Cp*Ru (η6-C6H5CO2Me)]+[BP h 4]- (8). A mixture of Cp*RuCl-
(cod) (75.9 mg, 0.20 mmol), trans-6a (0.50 mmol), and ethanol
(5.0 mL) was placed in a two-necked 20-mL Pyrex flask
equipped with a magnetic stirring bar under a flow of argon.
The mixture was magnetically stirred at 50 °C for 5 h. After
the mixture was cooled, the solvent was evaporated and the
orange residue was washed with pentane (10 mL × 2), followed
by drying in vacuo to give 73.4 mg (0.18 mmol, 90%) of [Cp*Ru-
(η6-C6H5CO2Me)]+[Cl]- (7) as an orange powder. Mp: 277.2-
Ack n ow led gm en t. This work was supported in part
by a Grant-in-Aid for Scientific Research from the
Ministry of Education, Science, Sports and Culture of
J apan. Y.M. appreciates Research Fellowships from the
J apan Society for the Promotion of Science for Young
Scientists.
279.5 °C dec. IR (KBr): 1726 cm-1 1H NMR (270 MHz,
.
CD2Cl2): δ 2.16 (s, 15H), 4.06 (s, 3H), 6.72 (br, 2H), 7.26-
7.31 (br, 2H), 7.70-7.71 (br, 1H).
A mixture of complex 7 (73.4 mg, 0.18 mmol), NaBPh4 (68.4
mg, 0.20 mmol), and acetone (2.0 mL) was placed in a two-
necked 20-mL Pyrex flask equipped with a magnetic stirring
bar under a flow of argon. The mixture was magnetically
stirred at room temperature. After 2 h, the white precipitate
(NaCl) was filtered off and washed with acetone (5 mL × 2).
The combined filtrate was evaporated, and the orange residue
Su p p or tin g In for m a tion Ava ila ble: Tables giving crys-
tal data and refinement details, positional and thermal
parameters, and bond distances and angles for [Cp*Ru(η6-
C6H5CO2Me)]+[BPh4]- (8). This material is available free of
charge via the Internet at http://pubs.acs.org.
OM990533K
(34) Sheldrick, G. M. Program for the Solution of Crystal Structures,
University of Go¨ttingen, Go¨ttingen, Germany, 1997.