Catalytic activation of C-H and C-C bonds of allylamines via olefin isomerization by transition metal complexes

Article abstract of DOI:10.1021/ol990357b

(matrix presented) The metal-catalyzed reaction of olefins with allylamines bearing coordination sites (2-pyridyl groups) was studied. With Ru₃(CO)₁₂ as catalyst, activation of C-H bonds led to the formation of ketimines that were hydrolyzed to give asymmetric ketones. With [(C₈H₁₄)₂RhCl]₂, both C-H and C-C bonds were activated and symmetric ketones were formed on hydrolysis. The reaction involves double bond migration of the allylamine to form an aldimine.

Full text of DOI:10.1021/ol990357b

ORGANIC
LETTERS
1999
Vol. 1, No. 13
2161-2164
Catalytic Activation of C−H and C−C
Bonds of Allylamines via Olefin
Isomerization by Transition Metal
Complexes
Chul-Ho Jun,* Hyuk Lee, Jae-Bum Park, and Dae-Yon Lee
Department of Chemistry, Yonsei UniVersity, Seoul 120-749, Korea
junch@alchemy.yonsei.ac.kr
Received November 12, 1999
ABSTRACT
The metal-catalyzed reaction of olefins with allylamines bearing coordination sites (2-pyridyl groups) was studied. With Ru3(CO)12 as catalyst,
activation of C−H bonds led to the formation of ketimines that were hydrolyzed to give asymmetric ketones. With [(C H ) RhCl]2, both C−H
8
14 2
and C−C bonds were activated and symmetric ketones were formed on hydrolysis. The reaction involves double bond migration of the allylamine
to form an aldimine.
Catalytic activation of C-H1,2 and C-C3,4 bonds has a broad
impact in organometallic chemistry because of its applica-
tions in organic synthesis. Aldehydic C-H bond activation5
and chelation-assisted hydroacylation6 were described earlier.
In particular, the use of 2-amino-3-picoline avoids decar-
bonylation effectively.7 Activation of the C-C bond in
ketones bearing â-hydrogen using chelation assistance has
also been documented.8 Aldimines and ketimines are pos-
tulated intermediates for these C-H and C-C bond activa-
tions. Catalytic activation of aromatic aldehydes with
2-amino-3-picoline is more efficient than activation of
aliphatic aldehydes.7a,9 The formation of aminal side products
during the reaction with aliphatic aldehydes reduces the
yields. Double bond migration of allylamines in the presence
of transition metal complexes provides a versatile approach
to the preparation of aldimines of the aliphatic alkyl group.10
(1) For recent reviews, see: (a) Ryabov, A. D. Chem. ReV. 1990, 90,
403-424. (b) Shilov, A. E.; Shul’pin, G. B. Chem. ReV. 1997, 97, 2879-
2932. (c) Dyker, G. Angew. Chem., Int. Ed. 1999, 38, 1698-1712.
(2) (a) Jun, C.-H.; Hwang, D.-C.; Na, S.-J. Chem. Commun. 1998, 1405-
1406. (b) Lim, Y.-G.; Kang, J.-B.; Kim, Y. H. J. Chem. Soc., Perkin Trans.
1 1998, 699-707. (c) Fukuyama, T.; Chatani, N.; Tatsumi, J.; Kakiuchi,
F.; Murai, S. J. Am. Chem. Soc. 1998, 120, 11522-11523. (d) Niu, S.;
Hall, M. B. J. Am. Chem. Soc. 1998, 120, 6169-6170. (e) Chatani, N.;
Ishii, Y.; Ie, Y.; Kakiuchi, F.; Murai, S. J. Org. Chem. 1998, 63, 5129-
5136. (f) Sonoda, M.; Kakiuchi, F.; Chatani, N.; Murai, S. Bull. Chem.
Soc. Jpn. 1997, 70, 3117-3128 and references therein.
(5) For intermolecular hydroacylation: (a) Legens, C. P.; White, P. S.;
Brookhart, M. J. Am. Chem. Soc. 1998, 120, 6965-6979. (b) Kondo, T.;
Hiraishi, N.; Morisaki, Y.; Wada, K.; Watanabe, Y.; Mitsudo, T. Organo-
metallics 1998, 17, 2131-2134. (c) Legens, C. P.; Brookhart, M. J. Am.
Chem. Soc. 1997, 119, 3165-3166. (d) Kondo, T.; Akazome, M.; Tsuji,
Y.; Watanabe, Y. J. Org. Chem. 1990, 55, 1286-1291. (e) Tetsuo, T.; Kiyoi,
T.; Saegusa, T. J. Org. Chem. 1990, 55, 2554-2558. (f) Kokubo, K.;
Matsumasa, K.; Miura, M.; Nomura, M. J. Org. Chem. 1997, 62, 4564-
4565. (g) Marder, T. B.; Roe, D. C.; Milstein, D. Organometallics 1988, 7,
1451-1453 and references therein.
(6) Jun, C.-H.; Hong, J.-B.; Lee, D.-Y. Synlett 1999, 1-12.
(7) (a) Jun, C.-H.; Lee, H.; Hong, J.-B. J. Org. Chem. 1997, 62, 1200-
1201. (b) Jun, C.-H.; Lee, D.-Y.; Hong, J.-B. Tetrahedron Lett. 1997, 38,
6673-6676. (c) Jun, C.-H.; Huh, C.-W.; Na, S.-J. Angew. Chem., Int. Ed.
1998, 37, 145-147. (d) Jun, C.-H.; Hong, J.-B. Org. Lett. 1999, 1, 887-
889.
(3) For a review on C-C bond activation, see: Rybtchinski, B.; Milstein,
D. Angew. Chem., Int. Ed. 1999, 38, 870-883.
(4) For catalytic C-C bond activation: (a) Kondo, T.; Kodoi, K.;
Nishinaga, E.; Okada, T.; Morisaki, Y.; Watanabe, Y.; Mitsudo, T. J. Am.
Chem. Soc. 1998, 120, 5587-5588. (b) Murakami, M.; Itahashi, T.; Amii,
H.; Takahashi, K.; Ito, Y. J. Am. Chem. Soc. 1998, 120, 9949-9950. (c)
Liou, S.-Y.; van der Boom, M. E.; Milstein, D. Chem. Commun. 1998,
687-688. (d) Murakami, M.; Takahashi, K.; Amii, H.; Ito, Y. J. Am. Chem.
Soc. 1997, 119, 9307-9308. (e) Harayama, H.; Kuroki, T.; Kimura, M.;
Tanaka, S.; Tamaru, Y. Angew. Chem., Int. Ed. Engl. 1997, 36, 2352-
2354. (f) Lin, M.; Hogan, T.; Sen. A. J. Am. Chem. Soc. 1997, 119, 6048-
6053. (g) Murakami, M.; Amii, H.; Shigeto, K.; Ito, Y. J. Am. Chem. Soc.
1996, 118, 8285-8290 and references therein.
(8) Jun, C.-H.; Lee, H. J. Am. Chem. Soc. 1999, 121, 880-881.
(9) Suggs, J. W. J. Am. Chem. Soc. 1979, 101, 489.
10.1021/ol990357b CCC: $18.00 © 1999 American Chemical Society
Published on Web 12/10/1999

In this report, we describe synthesis of ketones from
allylamines via catalytic activation of C-H and C-C bonds
using organotransition metal complexes Ru3(CO)12 and
[(C8H14)2RhCl]2. The products of these reactions are hydro-
lyzed under acidic conditions to form asymmetric and/or
symmetric ketones.
Two plausible mechanisms for the conversion of 1a to 4a
are illustrated in Scheme 1. Path A represents a well-known
Scheme 1
The reaction is exemplified by the synthesis of ketone 5a
(eq 1). N-(3-Methyl-2-pyridyl)-N-[(E)-3-phenyl-2-propenyl]-
organotransition metal catalyzed double bond migration10 of
1a to form aldimine 6 followed by hydroiminoacylation of
2a.
Path B involves allylic alkylation of 1a by 1-hexene (2a)
and subsequent double bond migration of 7. In a very recent
paper, we reported a similar type of alkylation of benzyl-
amine with 1-alkenes through benzylic C-H bond activation
catalyzed by Ru(0).2a To distinguish between the two
mechanisms, we tested both tertiary amine 8 and homo-
allylamine 9 under the reaction conditions. When treated with
amine (1a) was first converted to the corresponding ketimine
4a. The reaction was performed in toluene at 130 °C with 3
equiv of 1-hexene (2a) and catalytic amount of Ru3(CO)12
(3a) and gave a 90% yield. Acid hydrolysis of this product
afforded 1-phenyl-3-nonanone (5a) in an 84% yield based
upon 1a.
To establish the scope of this reaction, allylamines 1a (R1
) phenyl), 1b (R1 ) methyl), and 1c (R1 ) H) were allowed
to react with various 1-alkenes under identical conditions.
They gave the corresponding ketones, and Table 1 sum-
marizes the products and yields from these substrates.
Table 1. Reaction of Allylamines 1 with 1-Alkene (2) in the
Presence of Ru3(CO)12
2a in the presence of 3a, tertiary amine 8 did not undergo
alkylation. However, exposure of 9 to 2a followed by
hydrolysis generated 5d in 85% yield.11 This suggested path
A, double bond migration followed by hydroiminoacylation,
as the likely mechanism.
When water was present in the reaction of 1a and 2a, in
situ hydrolysis of 4a occurred and ketone 5a was obtained
in 74% yield (eq 2). This suggests that the intermediate
aldimine undergoes hydroiminoacylation much faster than
(10) (a) Jardine F. H. The Use of Organometallic Compounds in Organic
Synthesis. In The Chemistry of the Metal-Carbon Bond; Hartley, F. R.,
Ed.; John Wiley & Sons: New York, 1987; pp 736-740. (b) Inoue, S.;
Takaya, H.; Tani, K.; Otuska, S.; Sato, T.; Noyori, R. J. Am. Chem. Soc.
1990, 112, 4897-4905. (c) Noyori, R.; Takaya, H. Acc. Chem. Res. 1990,
23, 345-350. (d) Tani, K.; Yamagata, T.; Akutagawa, S.; Kumobayashi,
H.; Taketomi, T.; Takaya, H.; Miyashita, A.; Noyori, R.; Otsuka, S. J. Am.
Chem. Soc. 1984, 106, 5208-5217.
2162
Org. Lett., Vol. 1, No. 13, 1999

Table 2. Reactions of 1a with Various 1-Alkenes (2) in the Presence of [(C8H14)2RhCl]2
hydrolysis and that H2O participates only in the hydrolysis
of ketimine 4a.
6 which reacts with [(C8H14)2RhCl]2 and Cy3P to form
iminoacylrhodium(III) hydride 12.13 The hydroiminoacylation
When the coupling reaction of 1a and 2a (10 equiv of
1a) was carried out at 170 °C in the presence of 3 mol % of
[(C8H14)2RhCl]2 (3b) and 6 mol % of tricyclohexylphosphine
(Cy3P) without solvent,12 ketimines 10a was obtained along
with a small amount of 4a (10a:4a ) 96:4). After acid
hydrolysis, 11a and 5a were isolated in 91% and 3% yields,
respectively (eq 3).
of 1-hexene (2a) with 12 gives ketimine 4a. Probably, anti-
syn isomerization of the imine14 that occurs easily under the
reaction conditions may lead to the formation of ketimine
13. The C-C bond activation of 13 followed by hydroimino-
acylation of 2a generates ketimine 10a. Among the various
catalytic systems examined, the [(C8H14)2RhCl]2 and Cy3P
system has proven to be most effective.15
The rate of alkylation of 1a with various 1-alkenes was
also measured. Table 2 summarizes the products and yields.
With sterically hindered olefin such as 3,3-dimethyl-1-butene
(2b), the reaction was completed within 15 min (Table 2,
entry 3). Activations of C-C bond using other catalytic
systems require much longer exposure times (9-48 h).4 After
1a disappeared completely, prolonged reaction times increase
the 11b to 5b ratio from 85/15 to 95/5 (entries 3-5). Alkenes
2c-e reacted with 1a and yielded the corresponding sym-
metric (11) and asymmetric (5) ketones upon hydrolysis
(Table 2, entries 6-8).
The sequence of the events in this reaction appears to be
as follows: Double bond migration of 1a generates aldimine
(11) Double bond migration of homoallylamine is not common for the
metal catalyzed reaction. However, the coordination by 2-pyridyl group in
9 might provide a directing effect for this isomerization.
(12) When the reaction was carried out in toluene, a mixture of 4a and
10a was obtained in a 20:80 ratio.
Org. Lett., Vol. 1, No. 13, 1999
2163

In conclusion, allylamines bearing coordination sites such
as the 2-pyridyl group can react with olefins in the presence
of Ru(0) to give asymmetric ketones. However, Rh(I)
catalysis of these coupling reactions provided the corre-
sponding symmetric ketones as well. These results indicate
that Ru(0) complexes activate the C-H bond selectively and
Rh(I) complexes activate both C-H and C-C bonds.
Acknowledgment. This work was supported by the
Korean Science and Engineering Foundation (97-05-01-05-
01-3).
(13) This intermediate was formed and isolated in a control reaction in
which 1a reacted with 3b and Cy3P in the absence of 2a at 100 °C for 2 h.
12: 1H NMR (500 MHz, CDCl3) δ (ppm) 9.11 (d, J ) 4.5 Hz, 1H, 6-H in
picoline group), 7.48 (d, J ) 7.5 Hz, 4-H in picoline group), 7.30-7.16
(m, 5Hs, 2,3,4,5,6-Hs in phenyl group), 6.89 (t, J ) 6.3 Hz, 1H, 5-H in
picoline group), 3.28 (t, J ) 7.1 Hz, 2Hs, R-CH2 to CdN), 3.21 (t, J ) 7.0
Hz, 2Hs, â-CH2 to CdN), 2.50 (s, 3Hs, CH3- in picoline group), -13.54
(overlapping d of t, J ) 14.5 Hz, J ) 14.5 Hz, 1H, H-Rh); 13C NMR (125
MHz, CDCl3) δ (ppm) 232.11 (d, J ) 124 Hz, CdN); IR spectrum (KBr)
3024, 2921, 2850, 2659, 2129, 2025, 1591, 1447, 1406, 1270, 1001, 847,
734 cm-1; HRMSFAB calcd for C51H82ClN2P2Rh (M+) 922.4664, found
922.4694.
(14) Wettermark, G. In The Chemistry of Carbon-Nitrogen Double
Bond; Patai, S., Ed.; Interscience Publisher: London, 1970; pp 574-582.
(15) Other ligands such as triphenylphosphine, tri(p-toly)phosphine, tri-
(p-methoxyphenyl)phosphine, tributylphosphine, and dicyclohexylphenyl-
phosphine were tested in this reaction with 3b but were not as efficient as
Cy3P.
Supporting Information Available: Experimental pro-
cedures for the preparation of allylamine derivatives 1a-c,
8, and 9, catalytic C-H bond activation of 1a with 1-hexene
by Ru3(CO)12 and the same reaction adding H2O, and
catalytic C-H bond and C-C bond activation of 1a with
1-hexene by [(C8H14)2RhCl]2 and Cy3P, including the char-
acterization data for 1a-c, 4a, 5b, 5e, 8, 9, and 10a. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OL990357B
2164
Org. Lett., Vol. 1, No. 13, 1999