Carbonylative [5 + 1] cycloaddition of cyclopropyl imines catalyzed by ruthenium carbonyl complex

Full text of DOI:10.1021/jo000795s

9230
J . Org. Chem. 2000, 65, 9230-9233
Sch em e 1
Ca r bon yla tive [5 + 1] Cycloa d d ition of
Cyclop r op yl Im in es Ca ta lyzed by
Ru th en iu m Ca r bon yl Com p lex
Akihito Kamitani, Naoto Chatani,
Tsumoru Morimoto,† and Shinji Murai*
Department of Applied Chemistry, Faculty of Engineering,
Osaka University, Suita, Osaka 565-0871, J apan
are rare examples of catalytic carbonylative cycloaddi-
tions to give six-membered carbonyl compounds.11 A [5
+ 1] mode, which involves the ring-opening of cyclopro-
pane, would be of great potential for the construction of
six-membered carbonyl compounds. Wender extensively
studied catalytic cycloaddition reactions which involve
the opening of a cyclopropane ring.12 We expected that
cyclopropyl imines might function as a five-assembling
unit on their ring-opening. We report herein the Ru3-
(CO)12-catalyzed carbonylative [5 + 1] mode of cycload-
dition of cyclopropyl imines leading to six-membered
unsaturated lactams (Scheme 1).
The reaction of the cyclopropyl imine 1a (anti/syn )
3.3/1, 1 mmol), which was derived from cyclopropyl
phenyl ketone and tert-butylamine, with CO (initial
pressure 2 atm at 25 °C) in toluene (3 mL) in the presence
of a catalytic amount of Ru3(CO)12 (0.02 mmol) at 160 °C
for 20 h gave 3,4-dihydro-1-(1,1-dimethylethyl)-6-phenyl-
2(1H)-pyridinone (2a )13 in 57% isolated yield after silica
gel column chromatography (eq 1). No other carbonyla-
tion products could be detected. Prolongation of the
reaction time (60 h) resulted in complete consumption
of 1a , and the yield increased to 76%. When the reaction
was carried out at 140 or 180 °C, only traces of 2a were
formed in both cases. A higher pressure (10 atm) at 160
°C also gave only trace amounts of 2a . Of the solvents
examined (dioxane 26% yield, CH3CN 0%, cyclohexane
30%), toluene (57%) was the solvent of choice when the
reaction was run at 160 °C under 2 atm of CO for 20 h.
Changing the substituent on the imine nitrogen to
PhCH2, p-MeOC6H4, or OMe resulted in no detectable
corresponding product formation. However, the use of a
cyclohexyl group as the N-substituent, such as in 1b, gave
a comparable yield (61%) of the corresponding γ-lactam
2b. The N-substituent of choice is dependent on the
structure of substrates used (vide infra).
murai@chem.eng.osaka-u.ac.jp
Received J uly 21, 2000
Transition-metal-catalyzed cycloaddition reactions which
use carbon monoxide as a one-carbon unit represent one
of the attractive methods for the preparation of cyclic
carbonyl compounds.1-4 Of the carbonylative cycloaddi-
tion reactions, a [2 + 2 + 1] cycloaddition reaction, which
leads to the construction of five-membered carbonyl
compounds, is the most popular. We recently reported
the first use of a ruthenium complex4 in the catalytic
Pauson-Khand-type reaction,3 which can be used for the
[2 + 2 + 1] cycloaddition of alkynes, alkenes, and carbon
monoxide leading to the formation of R,â-unsaturated
cyclopentenones. A [2 + 2 + 1] cycloaddition of alkynes
(or alkenes), aldehydes (or ketones), and carbon monoxide
leading to γ-butyrolactone derivatives was achieved by
the use of a ruthenium complex5-8 or titanium complex.9
We also reported the Ru-catalyzed [4 + 1] cycloaddition
of R,â-unsaturated imines with carbon monoxide, which
gives γ-butyrolactams.10 It is also noteworthy that there
* To whom correspondence should be addressed.
† Present address: Graduate School of Materials Science, Nara
Institute of Scientific and Technology (NAIST), Takayama, Ikoma,
Nara 630-0101, J apan.
(1) For general reviews on transition-metal-catalyzed cycloaddition
reactions, see: Lautens, M.; Klute, W.; Tam, W. Chem. Rev. 1996, 96,
49. Ojima, I.; Tzamarioudaki, M.; Li, Z.; Donovan, R. J . Chem. Rev.
1996, 96, 635.
(2) For recent papers on carbonylative cycloaddition reactions see
the following. [2 + 2 + 1]: Suzuki, N.; Kondo, T.; Mitsudo, T.
Organometallics 1998, 17, 766. [4 + 1]: Murakami, M.; Itami, K.; Ito,
Y. J . Am. Chem. Soc. 1999, 121, 4130. [4 + 4 + 1]: Murakami, M.;
Itami, K.; Ito, Y. Angew. Chem., Int. Ed. Engl. 1998, 37, 3418.
(3) For a recent review on the Pauson-Khand type reaction, see:
Chung, Y. K. Coord. Chem. Rev. 1999, 188, 297. For recent papers on
the catalytic Pauson-Khand type reaction, see: Koga, Y.; Kobayashi,
T.; Narasaka, K. Chem. Lett. 1998, 249. J eong, N.; Lee, S.; Sung, B.
K. Organometallics 1998, 17, 3642. Belanger, D. B.; Livinghouse, T.
Tetrahedron Lett. 1998, 39, 7641. Sugihara, T.; Yamaguchi, M. J . Am.
Chem. Soc. 1998, 120, 10782. Kraft, M. E.; Hirosawa, C.; Bonaga, L.
V. R. Tetrahedron Lett. 1999, 40, 9177. Hicks, F. A.; Buchwald, S. L.
J . Am. Chem. Soc. 1999, 121, 7026. Hiroi, K.; Watanabe, T.; Kawagishi,
R.; Abe, I. Tetrahedron Lett. 2000, 41, 891. Kim, S.-W.; Son, S. U.;
Lee, S. I.; Hyeon, T.; Chung, Y. K. J . Am. Chem. Soc. 2000, 122, 1550.
(4) Morimoto, T.; Chatani, N.; Fukumoto, Y.; Murai, S. J . Org. Chem.
1997, 62, 3762. A similar transformation was reported after our report
appeared. Kondo, T.; Suzuki, N.; Okada, T.; Mitsudo, T. J . Am. Chem.
Soc. 1997, 119, 6187.
(5) Chatani, N.; Morimoto, T.; Fukumoto, Y.; Murai, S. J . Am. Chem.
Soc. 1998, 120, 5335.
(6) Chatani, N.; Morimoto, T.; Kamitani, A.; Fukumoto, Y.; Murai,
S. J . Organomet. Chem. 1999, 579, 177.
(7) Chatani, N.; Tobisu, M.; Asaumi, T.; Fukumoto, Y.; Murai, S. J .
Am. Chem. Soc. 1999, 121, 7160.
(8) Chatani, N.; Tobisu, M.; Asaumi, T.; Murai, S. Synthesis 2000,
925.
(9) Kablaoui, N. M.; Hicks, F. A.; Buchwald, S. L. J . Am. Chem. Soc.
1996, 118, 5818. Kablaoui, N. M.; Hicks, F. A.; Buchwald, S. L. J . Am.
Chem. Soc. 1997, 119, 4424.
(10) Morimoto, T.; Chatani, N.; Murai, S. J . Am. Chem. Soc. 1999,
121, 1758.
No reaction was observed when other transition metal
complexes, such as Cp*RuCl(cod), Ru(CO)2(PPh3)3, RuH2-
10.1021/jo000795s CCC: $19.00 © 2000 American Chemical Society
Published on Web 12/01/2000

Notes
J . Org. Chem., Vol. 65, No. 26, 2000 9231
Ta ble 1. Ru 3(CO)12-Ca ta lyzed Rea ction of Cyclop r op yl
Im in es w ith COa
derived from cyclopropyl methyl ketone and tert-buty-
lamine, under the same reaction conditions as in eq 1
for 20 h gave the corresponding lactam 5a in 25% yield.
The use of additional catalyst (0.05 mmol) and a longer
reaction time (40 h) led to a slight increase in the yield
of 5a to a 34% yield (entry 1). The replacement of the
tert-butyl group in 4a with a cyclohexyl group as the
N-protecting group, as in 4b, gave 5b in 71% yield (entry
2). Cyclopropyl aldimine 6 was also used in this present
cyclocarbonylation reaction (entry 3). The reaction of 8
gave 9 in 27% yield, along with 61% of the starting 8
which was recovered as the corresponding ketone after
column chromatography on silica gel (entry 4). Use of
additional catalyst (0.05 mmol) and a prolonged reaction
time (40 h) did not result in an increased yield of 9,
although 8 was completely consumed. In the case of
substrates 8 and 10 (entries 4 and 5), the replacement
of the tert-butyl group by a cyclohexyl group had no effect
on the product yields (not shown). The introduction of a
methyl group at the 1-position (R to the imine carbonyl
carbon) of the cyclopropane ring, as in 12, resulted in the
formation of the corresponding lactam 13 in good yield
(entry 6).
In contrast to 12, cyclopropyl phenyl ketimines which
contain a methyl or phenyl group at the 2-position on
the cyclopropane ring could not be used in the present
reaction. In these cases, complex mixtures were obtained
and it was not possible to isolate the corresponding
lactams in a pure form. In the case of the reaction of
aldimine 14, a mixture of the expected lactams 15 and
16 was obtained in a total yield of 30% and the aldehyde
17 in 10%, along with 23% of the imine being recovered
as trans-2-phenylcyclopropancarboxaldehyde (eq 3). We
propose that aldehyde 17 is formed from the same key
intermediate, leading to 16. The course of the reaction
in which aldehyde 17 is formed will be discussed below.
a
Reaction conditions: imine (1 mmol), CO (2 atm at 25 °C),
b
Ru3(CO)12 (0.05 mmol) in toluene (3 mL) at 160 °C. Ru3(CO)12
(0.02 mmol).
(CO)(PPh3)3, Ru(acac)3, [RuCl2(CO)3]2, Co2(CO)8, IrCl-
(CO)(PPh3)2, and [IrCl(CO)3]n, were used as catalysts.
When the reaction was run in the presence of [RhCl-
(CO)2]2 as the catalyst, no carbonylation products were
obtained, but instead, the pyrrole derivative 3 was formed
in 49% yield (eq 2). Product 3 was formed by the
dehydrogenation of dihydropyrrole, which would be formed
by an aza-version of the vinylcyclopropane rearrange-
ment.
The results of the reaction of some cyclopropyl imines15
with CO are shown in Table 1. The reaction of imine 4a ,
(11) [5 + 1]: Murakami, M.; Itami, K.; Ubukata, M.; Tsuji, I.; Ito,
Y. J . Org. Chem. 1998, 63, 4. For a paper on Fe(CO)5-mediated [5 + 1]
cycloaddition of vinylcyclopropane and CO, see: Sarel, S.; Felzenstein,
A.; Victor, R.; Yovell, J . J . Chem. Soc., Chem. Commun. 1974, 1025.
(12) Wender, P. A.; Glorius, F.; Husfeld, C. O.; Langkopf, E.; Love,
J . A. J . Am. Chem. Soc. 1999, 121, 5348 and references therein.
(13) All new compounds were characterized by NMR, IR, mass
spectral data and by elemental analyses or high-resolution mass
spectra. See Supporting Information.
A proposed mechanism for the reaction is shown in
Scheme 2. The coordination of a nitrogen to ruthenium
facilitates the conversion to metallacycle A via an oxida-
tive cyclization of the cyclopropyl imine.16 The insertion
(14) Ben-Shoshan, R.; Sarel, S. Chem. Commun. 1996, 883.
(15) Ketimines were used as a syn and anti mixture.

9232 J . Org. Chem., Vol. 65, No. 26, 2000
Notes
Sch em e 2
of CO in A gives the acyl complex B,17 which undergoes
a reductive elimination to give the lactam. Compared
with the carbonylative [4 + 1] cycloaddition of R,â-
unsaturated imines which leads to the formation of
unsaturated γ-butyrolactams reported previously,10 the
efficiency of the present reaction is relatively low. The
reason for this may be the formation of aldehydes as
byproducts. The latter are probably formed via a â-hy-
dride elimination from A. The presence of a substituent
at the 2-position on the cyclopropane ring facilitates the
â-hydride elimination from A because the resulting
alkene complex C is more stable than that derived from
the nonsubstituted substrate. In contrast, there is no
â-hydrogen available for elimination in a similar metal-
lacycle complex derived from R,â-unsaturated imines.
When a rhodium complex is used as the catalyst, the
pyrrole 3 is formed (eq 2) by reductive elimination from
the Rh complex corresponding to A, followed by dehy-
drogenation and subsequent aromatization.
bath at 160 °C. After 60 h had elapsed, the autoclave was
removed from the oil bath and cooled for 1 h, followed by release
of the CO. The contents were transferred to a round-bottomed
flask with ether and the volatiles removed in vacuo. The residue
was subjected to column chromatography on silica gel (eluent,
hexane/Et2O ) 3/1) to give 3,4-dihydro-1-(1,1-dimethylethyl)-6-
phenyl-2(1H)-pyridinone (2a ) (175 mg, 76% yield) as a white
solid.
3,4-Dih yd r o-1-(1,1-d im eth yleth yl)-6-p h en yl-2(1H)-p yr i-
d in on e (2a ). White solid; mp 78-80 °C (hexane); Rf 0.14
(hexane/ether ) 3/1); 1H NMR (CDCl3) δ 1.35 (s, 9H), 2.17-2.24
(m, 2H), 2.44-2.49 (m, 2H), 5.69 (t, J ) 5.7 Hz, 1H), 7.25-7.35
(m, 5H); 13C NMR (CDCl3) δ 19.8, 30.3, 37.3, 59.9, 119.1, 125.6,
127.2, 128.2, 141.3, 145.3, 176.2; IR (KBr) 1688 s, 1598 m; MS
m/z (relative intensity, %) 229 (M+, 7), 173 (100); exact mass
calcd for C15H19NO 229.1467, found 229.1473.
1-Cycloh exyl-3,4-dih ydr o-6-ph en yl-2(1H)-pyr idin on e (2b).
White solid; mp 106-108 °C (hexane); Rf 0.16 (hexane/ether )
3/1); 1H NMR (CDCl3) δ 0.84-1.67 (m, 8H), 2.23-2.38 (m, 4H),
2.47-2.53 (m, 2H), 3.09 (tt, J ) 3.2 Hz, J ) 12.2 Hz, 1H), 5.34
(t, J ) 4.9 Hz, 1H), 7.27-7.37 (m, 5H); 13C NMR (CDCl3) δ 19.9,
25.2, 26.5, 29.9, 34.2, 59.7, 111.5, 127.1, 127.9, 128.2, 137.5,
144.4, 172.3; IR (KBr) 1674 s; MS m/z (relative intensity, %) 255
(M+, 20), 173 (100); exact mass calcd for C17H21NO 255.1623,
found 255.1625.
1-Bu tyl-3,4-Dih ydr o-6-ph en yl-2(1H)-pyr idin on e (2c). White
solid; mp 64-65 °C (hexane); Rf 0.09 (hexane/ether ) 3/1); 1H
NMR (CDCl3) δ 0.74 (t, J ) 7.3 Hz, 3H), 1.04-1.18 (m, 2H),
1.26-1.36 (m, 2H), 2.30-2.37 (m, 2H), 2.54-2.59 (m, 2H), 3.54
(t, J ) 7.3 Hz, 2H), 5.36 (t, J ) 4.9 Hz, 1H), 7.24-7.38 (m, 5H);
13C NMR (CDCl3) δ 13.7, 19.7, 19.9, 30.7, 32.3, 42.3, 110.4, 127.6,
128.0, 128.1, 136.1, 142.8, 171.4; IR (KBr) 1662 s; MS m/z
(relative intensity, %) 229 (M+, 47), 158 (100); exact mass calcd
for C15H19NO 229.1467, found 229.1463.
1-(1,1-Dim eth yleth yl)-2-p h en yl-(1H)-p yr r ole (3). White
solid; mp 57-59 °C (hexane); Rf 0.67 (hexane/ether ) 3/1); 1H
NMR (CDCl3) δ 1.43 (s, 9H), 6.01 (dd, J ) 3.2 Hz, J ) 1.9 Hz,
1H), 6.14 (dd, J ) 3.2 Hz, J ) 3.0 Hz, 1H), 6.91 (dd, J ) 3.0 Hz,
J ) 1.9 Hz, 1H), 7.31-7.41 (m, 5H); 13C NMR (CDCl3) δ 31.9,
57.1, 105.6, 111.7, 118.7, 127.2, 127.4, 131.7, 133.9, 137.2; IR
(KBr) 1693 w, 1628 w; MS m/z (relative intensity, %) 199 (M+,
11), 143 (100); exact mass calcd for C14H17N 199.1361, found
199.1365.
3,4-Dih yd r o-1-(1,1-d im eth yleth yl)-6-m eth yl-2(1H)-p yr i-
d in on e (5a ). Colorless oil; Rf 0.14 (hexane/ether ) 3/1); 1H NMR
(CDCl3) δ 1.50 (s, 9H), 1.92-1.99 (m, 2H), 2.00 (d, J ) 1.4 Hz,
3H), 2.31 (t, J ) 6.8 Hz, 2H), 5.40 (dt, J ) 1.4 Hz, J ) 4.9 Hz,
1H); 13C NMR (CDCl3) δ 19.4, 23.0, 30.3, 37.6, 57.4, 115.4, 139.1,
175.5; IR (neat) 1672 s; MS m/z (relative intensity, %) 167 (M+,
10), 83 (100); exact mass calcd for C10H17NO 167.1310, found
167.1311.
1-Cycloh exyl-3,4-dih ydr o-6-m eth yl-2(1H)-pyr idin on e (5b).
Colorless oil; Rf 0.06 (hexane/ether ) 3/1); 1H NMR (CDCl3) δ
1.18-1.77 (m, 8H), 1.93 (d, J ) 1.4 Hz, 3H), 2.04-2.07 (m, 2H),
2.27-2.44 (m, 4H), 3.56 (tt, J ) 3.2 Hz, J ) 11.9 Hz, 1H), 5.01
(dt, J ) 1.4 Hz, J ) 4.3 Hz, 1H); 13C NMR (CDCl3) δ 19.3, 19.9,
25.3, 26.5, 32.3, 33.7, 56.3, 106.8, 137.1, 171.5; IR (neat) 1675 s,
1626 m; MS m/z (relative intensity, %) 193 (M+, 16), 111 (100);
exact mass calcd for C12H19NO 193.1466, found 193.1470.
In summary, we have demonstrated a new Ru-
catalyzed [5 + 1] cycloaddition of cyclopropyl imines with
carbon monoxide leading to γ,δ-unsaturated six-mem-
bered lactam derivatives. Catalytic carbonylative cyclo-
coupling holds considerable promise for the preparation
of cyclic carbonyl compounds.
Exp er im en ta l Section
Ma ter ia ls. Toluene, dioxane, CH3CN, and cyclohexane were
distilled from CaH2. Ru3(CO)12 and [RhCl(CO)2]2 were purchased
from Aldrich Chemical Co. and used after recrystallization from
hexane. Ketimines 1, 4, 8, 10, and 12 were prepared by the
treatment of the corresponding ketones with amines in the
presence of TiCl4.18 Aldimines 6 and 13 were prepared by the
treatment of the corresponding aldehydes with amines in the
presence of MgSO4.19
Typical P r ocedu r e. A 50-mL stainless autoclave was charged
with cyclopropyl phenyl N-(1,1-dimethylethyl) ketimine (1a ) (1
mmol, 201 mg), toluene (3 mL), and Ru3(CO)12 (0.02 mmol, 13
mg). The system was flushed with 10 atm of CO three times,
after which it was pressurized to 2 atm and immersed in an oil
(16) We have developed the ruthenium carbonyl-catalyzed carbo-
nylation reactions in which the coordination of an sp2-nitrogen atom
to a ruthenium is proposed to be a key step. Ie, Y.; Chatani, N.; Ogo,
T.; Marshall, D. R.; Fukuyama, T.; Kakiuchi, F.; Murai, S. J . Org.
Chem. 2000, 65, 1475 and references therein.
(17) We do not know whether CO insertion takes place into a Ru-C
bond or Ru-N bond in complex A. A stoichiometric reaction of related
complexes involved CO insertion into an Fe-N bond has been reported.
Freiken, N.; Schreuder, P.; Siebenlist, R.; Fru¨hauf, H.-W.; Vrieze, K.;
Kooijman, H.; Veldman, N.; Spek, A. L.; Fraanje, J .; Goubitz, K.
Organometallics 1996, 15, 2148.
(18) Kimpe, N. D.; Smaele, D. D.; Hofkens, A.; Dejaegher, Y.;
Kesteleyn, B. Tetrahedron 1997, 53, 10803.
(19) Sulmon, P.; Kimpe, N. D.; Verhe, R.; Buyck, L. D.; Schamp, N.
Synthesis 1986, 192.

Notes
1-Cycloh exyl-3,4-d ih yd r o-2(1H)-p yr id in on e (7). White
J . Org. Chem., Vol. 65, No. 26, 2000 9233
29.6, 33.5, 59.0, 117.1, 127.5, 128.0, 129.5, 135.9, 136.6, 171.2;
IR (KBr) 1602 m; MS m/z (relative intensity, %) 269 (M+, 24),
172 (100). Anal. Calcd for C18H23NO: C, 80.26; H, 8.60; N, 5.20.
Found: C, 80.11; H, 8.61; N, 5.19.
solid; mp 46-47 °C (hexane); Rf 0.11 (hexane/ether ) 3/1); 1H
NMR (CDCl3) δ 0.95-1.77 (m, 10H), 2.17-2.24 (m, 2H), 2.45 (t,
J ) 8.1 Hz, 2H), 4.36-4.46 (m, 1H), 5.10 (dt, J ) 4.1 Hz, J )
8.1 Hz, 1H), 6.08 (dt, J ) 1.4 Hz, J ) 8.1 Hz, 1H); 13C NMR
(CDCl3) δ 19.8, 25.4, 25.7, 30.9, 31.8, 51.0, 105.9, 125.2, 168.5;
IR (KBr) 1659 s; MS m/z (relative intensity, %) 179 (M+, 23), 97
(100). Anal. Calcd for C11H17NO: C, 73.69; H, 9.56; N, 7.82.
Found: C, 73.53; H, 9.54; N, 7.79.
1-Cycloh exyl-3,4-dih ydr o-3-ph en yl-2(1H)-pyr idin on e (15)
a n d 1-Cycloh exyl-3,4-d ih yd r o-4-p h en yl-2(1H)-p yr id in on e
(16). The 1H and 13C NMR spectra and IR data were obtained
as a 1.3:1 mixture of 15 and 16: yellow solid; mp 75-77 °C
1
(hexane); Rf 0.19-0.23 (hexane/ether ) 3/1); H NMR (CDCl3)
3,4-Dih yd r o-1-(1,1-d im eth yleth yl)-6-(2-th ien yl)-2(1H)-p y-
r id in on e (9). White solid; mp 91-93 °C (hexane); Rf 0.19
(hexane/ether ) 3/1); 1H NMR (CDCl3) δ 1.42 (s, 9H), 2.12-2.23
(m, 2H), 2.44-2.49 (m, 2H), 5.84 (t, J ) 3.2 Hz, 1H), 6.92-6.99
(m, 2H), 7.16 (dd, J ) 4.9 Hz, J ) 1.4 Hz, 1H); 13C NMR (CDCl3)
δ 19.9, 30.2, 37.4, 60.3, 119.4, 123.5, 123.6, 126.8, 138.7, 144.1,
176.0; IR (KBr) 1672 s, 1626 s; MS m/z (relative intensity, %)
235 (M+, 8), 179 (100); exact mass calcd for C13H17NOS 235.1029,
found 235.1030.
3,4-Dih yd r o-1-(1,1-d im eth yleth yl)-6-(4-m eth oxyp h en yl)-
2(1H)-p yr id in on e (11). White solid; mp 124-125 °C (hexane);
Rf 0.14 (hexane/ether ) 3/1); 1H NMR (CDCl3) δ 1.34 (s, 9H),
2.14-2.21 (m, 2H), 2.42-2.47 (m, 2H), 3.81 (s, 3H), 5.61 (t, J )
5.7 Hz, 3H), 6.85 (d, J ) 8.6 Hz, 2H), 7.22 (d, J ) 8.6 Hz, 2H);
13C NMR (CDCl3) δ 19.8, 30.4, 37.5, 55.3, 59.8, 113.6, 117.7,
126.9, 133.9, 144.9, 158.8, 176.3; IR (KBr) 1673 s, 1636 m; MS
m/z (relative intensity, %) 259 (M+, 5), 203 (100). Anal. Calcd
for C16H21NO2: C, 74.10; H, 8.16; N, 5.40. Found: C, 74.08; H,
8.19; N, 5.31.
δ 1.12-1.58 (m, 10H), 2.55-2.89 (m, 2H), 3.69-3.75 (m, 1H),
4.48-4.50 (m, 1H), [5.20 (dt, J ) 4.3 Hz, J ) 7.8 Hz, 15), 5.27
(dt, J ) 1.4 Hz, J ) 7.8 Hz, 16), 1H], [6.20 (dt, J ) 1.6 Hz, J )
7.8 Hz, 15), 6.29 (dt, J ) 1.9 Hz, J ) 7.8 Hz, 16), 1H], 7.12-
7.34 (m, 5H); 13C NMR (CDCl3) δ 25.5, 25.8, 28.0, 31.0, 31.1,
40.3, 47.2, 51.2, 51.8, [105.2 (15), 109.0 (16)], 125.4, 126.7, 126.9,
127.7, 128.3, 128.6, 139.7, 142.8, 167.5, 169.1; IR (KBr) 1670 s;
MS m/z (relative intensity, %) [255 (M+, 12), 118 (100), 15], [255
(M+, 42), 55 (100), 16]. Anal. Calcd for C17H21NO: C, 79.96; H,
8.29; N, 5.49. Found: C, 79.70; H, 8.40; N, 5.26.
Ack n ow led gm en t. This work was supported, in
part, by grants from Monbusho. We also acknowledge
the Instrumental Analysis Center, Faculty of Engineer-
ing, Osaka University, for assistance in obtaining
HRMS and elemental analyses.
Su p p or tin g In for m a tion Ava ila ble: Full characteriza-
tion of all the new compounds obtained including 1H NMR
spectra for all previously unknown starting materials and
cycloaddition products 2, 3, 5, and 9. This material is available
free of charge via the Internet at http://pubs.acs.org.
1-Cycloh exyl-3,4-d ih yd r o-5-m eth yl-6-p h en yl-2(1H)-p yr i-
d in on e (13). White solid; mp 79-81 °C (hexane); Rf 0.10
(hexane/ether ) 3/1); 1H NMR (CDCl3) δ 0.73-1.58 (m, 8H), 1.61
(s, 3H), 2.13-2.27 (m, 4H), 2.46-2.51 (m, 2H), 2.96 (tt, J ) 3.5
Hz, J ) 11.9 Hz, 1H), 7.18 (dd, J ) 1.9 Hz, J ) 7.8 Hz, 2H),
7.28-7.40 (m, 3H); 13C NMR (CDCl3) δ 19.4, 25.2, 26.4, 27.0,
J O000795S