Rhodium(I)-catalyzed intramolecular Pauson-Khand-type [2 + 2 + 1] cycloaddition of allenenes

Article abstract of DOI:10.1021/ol0600990

The novel [RhCl(CO)₂]₂-catalyzed [2 + 2 + 1] cycloaddition of allenenes leading to the bicyclo[4.3.0]non-1(9)-en-8-one as well as the bicyclo-[5.3.0]dec-1(10)-en-9-one skeletons has been developed. This method also provides a new pro

Full text of DOI:10.1021/ol0600990

ORGANIC
LETTERS
2006
Vol. 8, No. 6
1217-1220
Rhodium(I)-Catalyzed Intramolecular
Pauson Khand-Type [2 1]
Cycloaddition of Allenenes
−
+ 2 +
Fuyuhiko Inagaki and Chisato Mukai*
DiVision of Pharmaceutical Sciences, Graduate School of Natural Science and
Technology, Kanazawa UniVersity, Kakuma-machi, Kanazawa 920-1192, Japan
cmukai@kenroku.kanazawa-u.ac.jp
Received January 13, 2006
ABSTRACT
The novel [RhCl(CO)2]2-catalyzed [2
+ 2 + 1] cycloaddition of allenenes leading to the bicyclo[4.3.0]non-1(9)-en-8-one as well as the bicyclo-
[5.3.0]dec-1(10)-en-9-one skeletons has been developed. This method also provides a new procedure for the construction of the bicyclo[4.3.0]-
non-1(9)-en-8-one skeleton having an alkyl appendage at the ring juncture, which was hardly attained in a satisfactory yield by the Pauson
Khand reaction of the corresponding enynes.
−
The intramolecular Pauson-Khand reaction1 is a formal
metal-mediated (or -catalyzed) [2 + 2 + 1] cycloaddition
of the alkyne π-bond, the alkene π-bond, and carbon
monoxide (CO) and provides the straightforward as well as
powerful methodology for the construction of the cyclopen-
tenone-fused frameworks. This ring-closing reaction has been
almost exclusively limited to the use of the alkyne π-bond
as one of the two carbon-carbon π-bond components,
although the stepwise stoichiometric conversion2 of 1-phen-
ylhepta-1,6-diene (bis-alkene derivatives) into the carbon-
ylative bicyclo[3.3.0] compounds via the zirconacyclopentane
has been reported. Wender3 very recently reported the first
example of the [RhCl(CO)2]2-catalyzed [2 + 2 + 1]
cycloaddition of 1,3-dienes, alkenes, and CO, in which the
1,3-diene moiety served as the alkene π-bond4 instead of
the alkyne π-component. On the other hand, Itoh5 reported
an example of the [RhCl(CO)2]2-catalyzed intramolecular
[2 + 2 + 1] cycloaddition between the proximal double bond
of the allenyl moiety and a vinylsilane of (8E)-6,6-bis-
(methoxycarbonyl)-2-methyl-9-trimethylsilylnona-2,3,8-tri-
ene under 3 atm of CO resulting in the formation of
2-isopropylidenebicyclo[3.3.0]octan-3-ones. When allenenes
without a silyl group on the olefin moiety were exposed to
(1) For leading reviews, see: (a) Pauson, P. L. In Organometallics in
Organic Synthesis. Aspects of a Modern Interdisciplinary Field; de Meijere,
A., tom Dieck, H., Eds.; Springer: Berlin, 1988; pp 233-246. (b) Schore,
N. E. Chem. ReV. 1988, 88, 1081-1119. (c) Schore, N. E. Org. React.
1991, 40, 1-90. (d) Schore, N. E. In ComprehensiVe Organic Synthesis;
Trost, B. M., Ed.; Pergamon: Oxford, 1991; Vol. 5, pp 1037-1064. (e)
Schore, N. E. In ComprehensiVe Organometallic Chemistry II; Abel, E.
W., Stone, F. G. A., Wilkinson, G., Eds.; Elsevier: New York, 1995; Vol.
12, pp 703-739. (f) Fru¨hauf, H.-W. Chem. ReV. 1997, 97, 523-596. (g)
Jeong, N. In Transition Metals in Organic Synthesis; Beller, H., Bolm, C.,
Eds.; Wiley-VCH: Weinheim, 1998; Vol. 1, pp 560-577. (h) Geis, O.;
Schmalz, H.-G. Angew. Chem., Int. Ed. 1998, 37, 911-914. (i) Chung, Y.
K. Coord. Chem. ReV. 1999, 188, 297-341. (j) Brummond, K. M.; Kent,
J. L. Tetrahedron 2000, 56, 3263-3283. (k) Bon˜aga, L. V. R.; Krafft, M.
E. Tetrahedron 2004, 60, 9795-9833.
(2) Negishi, E.; Choueiry, D.; Nguyen, T. B.; Swanson, D. R.; Suzuki,
N.; Takahashi, T. J. Am. Chem. Soc. 1994, 116, 9751-9752.
(3) Wender, P. A.; Croatt, M. P.; Deschamps, N. M. J. Am. Chem. Soc.
2004, 126, 5948-5949.
(4) Wender reported that several bis-enes failed to give the [2 + 2 + 1]
products under the optimized [RhCl(CO)2]2-catalyzed conditions.3
(5) (a) Makino, T.; Itoh, K. Tetrahedron Lett. 2003, 44, 6335-6338.
(b) Makino, T.; Itoh, K. J. Org. Chem. 2004, 69, 395-405.
10.1021/ol0600990 CCC: $33.50
© 2006 American Chemical Society
Published on Web 02/23/2006

the Rh(I) catalyst, however, the ring-closing reaction pro-
ceeded in a different way to produce the seven-membered
monocyclic products instead of the Pauson-Khand-type
products.
Table 1. Rhodium(l)-Catalyzed [2 + 2 + 1] Cycloaddition
of 3a,b
Our recent interest6 in the development of the [RhCl-
(CO)2]2- or [RhCl(CO)dppp]2-catalyzed intramolecular Pau-
son-Khand-type reaction7 between the alkyne π-bond and
the allenyl π-bond of the phenylsulfonylallenynes 1 (al-
lenynes) in the presence of CO led to the easy preparation
of the bicyclo[4.3.0]nonadienone (n ) 1) as well as the
bicyclo[5.3.0]decadienone (n ) 2) frameworks 2 (Scheme
1). These observations prompted us to investigate the [RhCl-
mol CO
T
t
product
(%)
entry allenene Rh(l)
%
(atm) (°C) (h)
cis:transa
1
2
3
4
5
6
3a
3a
3a
3a
3b
3b
A
B
A
B
A
A
2.5
2.5
2.5
2.5
2.5
5
1
1
5
5
5
5
reflux 20 4a (64)b
reflux 10 4a (22)
120
120
120
120
21:79
21:79
21:79
21:79
62:38
62:38
2
4a (53)
Scheme 1
12 4a (96)
3
3
4b (74)
4b (77)
a Ratio was determined by 1H NMR. b The starting material 3a was
recovered in 30% yield.
(CO)2]2- or [RhCl(CO)dppp]2-catalyzed cyclocarbonylation
between the alkene π-bond and the allenyl π-bond of 1
(allenenes). We report herein the preliminary results of the
Rh(I)-catalyzed [2 + 2 + 1] cycloaddition of the alkene
π-bond, the distal π-bond of the allenyl moiety, and CO
resulting in the preparation of the bicyclo[4.3.0]nonenone
and bicyclo[5.3.0]decenone skeletons.
Our initial evaluation for the Rh(I)-catalyzed cyclocar-
bonylation of a phenylsulfonylallenene was carried out using
compounds 3a8 and 3b9 (Table 1). According to the
previously reported conditions6 for the Pauson-Khand-type
reaction of substrates 1 (allenynes), a solution of 3a in
toluene was refluxed for 20 h in the presence of 2.5 mol %
of [RhCl(CO)dppp]2 under an atmosphere of CO to afford
the desired 2-phenylsulfonylbicyclo[4.3.0]nonenone 4a in
64% yield as a mixture of the cis-4a and trans-4a10 in a
ratio of 21:79 (entry 1).11
improvement (4a, 96%) was observed when the ring-closing
reaction of 3a was carried out in the presence of [RhCl-
(CO)2]2 under 5 atm of CO at 120 °C (entry 4). [RhCl(CO)-
dppp]2 furnished 4a in 53% yield under 5 atm of CO (entry
3).12 The ring-closing reaction of 3b under 5 atm of CO with
a catalytic amount of [RhCl(CO)2]2 also proceeded as
expected to produce 4b in 74% yield (entry 5). Increase of
the loading amounts of [RhCl(CO)2]2 from 2.5 to 5 mol %
provided 4b in a similar yield (entry 6). The formation of 4
can be rationalized in terms of the intermediacy of the
initially formed 2-phenylsulfonylbicyclo[4.3.0]non-1-en-8-
one derivative 5, which should immediately isomerize to the
R,â-unsaturated ketones.
We next investigated the scope of the [RhCl(CO)2]2-
catalyzed ring-closing reaction under 5 atm of CO using
several 1,2,7-octatrienes 6. These results are summarized in
Table 2. The allenenes 6a,b, having a heteroatom on the alkyl
tether, consistently produced the corresponding bicyclic
compounds 7a,b in good yields (entries 1 and 2). The
6-alkylbicyclo[4.3.0]nonenone frameworks 7c-e could be
constructed from the 1,1-dialkylalkene derivatives 6c-e in
acceptable yields (entries 3-5), respectively. Similarly,
compound 6g with a trisubstituted allenyl moiety produced
7g in 51% yield along with its double bond isomer 9 (36%)
(entry 7). Whereas the Pauson-Khand reaction of the 2-alkyl
(or phenyl)-1-hepten-6-ynes are well-known to efficiently
afford the 5-alkyl (or phenyl) bicyclo[3.3.0]oct-1-en-3-
An alternative catalyst, [RhCl(CO)2]2, gave the ring-closed
products 4a in a rather lower yield (entry 2). A significant
(6) (a) Mukai, C.; Nomura, I.; Yamanishi, K.; Hanaoka, M. Org. Lett.
2002, 4, 1755-1758. (b) Mukai, C.; Nomura, I.; Kitagaki, S. J. Org. Chem.
2003, 68, 1376-1385. (c) Mukai, C.; Inagaki, F.; Yoshida, T.; Kitagaki, S.
Tetrahedron Lett. 2004, 45, 4117-4121. (d) Mukai, C.; Inagaki, F.; Yoshida,
T.; Yoshitani, K.; Hara, Y.; Kitagaki, S. J. Org. Chem. 2005, 70, 7159-
7171. (e) Mukai, C.; Hirose, T.; Teramoto, S.; Kitagaki, S. Tetrahedron
2005, 61, 10983-10994.
(7) Brummond independently developed the [RhCl(CO)2]2-catalyzed
Pauson-Khand-type [2 + 2 + 1] cycloaddition of allenynes. See: (a)
Brummond, K. M.; Chen, H.; Fisher, K. D.; Kerekes, A. D.; Rickards, B.;
Sill, P. C.; Geib, S. J. Org. Lett. 2002, 4, 1931-1934. (b) Brummond, K.
M.; Gao, D. Org. Lett. 2003, 5, 3491-3494. (c) Brummond, K. M.; Mitasev,
B. Org. Lett. 2004, 6, 2245-2248. (d) Brummond, K. M.; Curran, D. P.;
Mitasev, B.; Fischer, S. J. Org. Chem. 2005, 70, 1745-1753.
(8) Padwa, A.; Filipkowski, M. A.; Meske, M.; Watterson, S. H.; Ni, Z.
J. Am. Chem. Soc. 1993, 115, 3776-3777.
(9) The preparation and characterization of the unknown allenenes are
described in SI.
(12) During our investigations6 of the intramolecular Pauson-Khand-
type [2 + 2 + 1] cycloaddition of allenynes under an atmosphere of CO,
we found that [RhCl(CO)dppp]2 generally more efficiently catalyzed the
ring-closing reaction than [RhCl(CO)2]2, whereas the latter is much a more
effective catalyst compared to the former when the reaction was carried
out under CO pressure (5-10 atm). A similar behavior was observed in
the ring-closing reaction of 3.
1
(10) The relative stereochemistry was determined by H NMR spectral
considerations, in particular, by an NOE analysis.
(11) The ring-closing reaction of allenenes, having the other substituent
instead of a phenylsulfonyl group on the allenyl moiety, has not been
examined yet. The effect of a phenylsulfonyl group in this reaction will be
investigated in due course.
1218
Org. Lett., Vol. 8, No. 6, 2006

Table 2. [RhCl(CO)2]2-Catalyzed [2 + 2 + 1] Cycloaddition
of 1,2,7-Trienes
Table 3. [RhCl(CO)2]2-Catalyzed [2 + 2 + 1] Cycloaddition
of 1,2,8-Trienes
1
a Ratio was determined by H NMR. b Isolated as a single isomer.
a Ratio was determined by 1H NMR. b Isolated as a single isomer.
c Compound 9 was also obtained in 36% yield. d Starting material 6h was
recovered in 50% yield.
tion of allenenes, the formation of 817 would be interpreted
by the thermal [2 + 2] cycloaddition between the proximal
π-bond of the allenyl moiety and the terminal olefin. In fact,
(13) For selected references, see: (a) Jeong, N.; Hwang, S. H.; Lee, Y.;
Chung, Y. K. J. Am. Chem. Soc. 1994, 116, 3159-3160. (b) Pagenkopf,
B. L.; Livinghouse, T. J. Am. Chem. Soc. 1996, 118, 2285-2286. (c) Koga,
Y.; Kobayashi, T.; Narasaka, K. Chem. Lett. 1998, 249-250. (d) Sugihara,
T.; Yamaguchi, M. J. Am. Chem. Soc. 1998, 120, 10782-10783. (e) Hicks,
F. A.; Kablaoui, N. M.; Buchwald, S. L. J. Am. Chem. Soc. 1999, 121,
5881-5898. (f) Krafft, M. E. Bonaga, L. V. R.; Hirosawa, C. Tetrahedron
Lett. 1999, 40, 9171-9175. (g) Hiroi, K.; Watanabe, T.; Kawagishi, R.;
Abe, I. Tetrahedron Asymmetry 2000, 11, 797-808. (h) Fletcher, A. J.;
Christie, S. D. R. J. Chem. Soc., Perkin Trans. 1 2000, 1657-1668. (i)
Krafft, M. E.; Wright, J. A.; Bon˜aga, L. V. R. Synlett 2005, 71-74. (j)
Tang, Y.; Deng, L.; Zhang, Y.; Dong, G.; Chen, J.; Yang, Z. Org. Lett.
2005, 7, 593-595.
(14) Bolton obtained the azabicyclo[4.3.0]nonenone derivative, having
a methyl group at the ring juncture, in a less than 5% yield, whereas Ishizaki
and Hoshino prepared the bicyclo[4.3.0]nonenone derivative, having a
methyl group at the ring juncture, in 28% yield. See: (a) Bolton, G. L.;
Hodges, J. C.; Rubin, J. R. Tetrahedron 1997, 53, 6611-6634. (b) Ishizaki,
M.; Satoh, H.; Hoshino, O. Chem. Lett. 2002, 1040-1041. (c) Ishizaki,
M.; Satoh, H.; Hoshino, O.; Nishitani, K.; Hara, H. Heterocycles 2004, 63,
827-844.
ones,1,13 there are only two examples14 that described the
low yield formation of the one-carbon-homologated bicyclo-
[4.3.0] skeletons, possessing an alkyl appendage at the ring
juncture, from the acyclic enynes.15 Thus, the newly devel-
oped Pauson-Khand-type [2 + 2 + 1] cycloaddition of
allenenes would provide an efficient and general way for
preparing the bicyclo[4.3.0] skeletons, possessing an alkyl
group at the ring juncture. In sharp contrast to the alkyl
derivatives 6c-e, the phenyl congener 6f was transformed
into a different product, the bicyclo[3.2.0]heptane derivative
8, in 68% yield (entry 6). Based on Padwa’s extensive
studies8,16 on the thermal intramolecular [2 + 2] cycloaddi-
Org. Lett., Vol. 8, No. 6, 2006
1219

compound 8 was obtained by simply heating in toluene at
120 °C without the Rh(I)-catalyst. The tetrasubstituted allene
derivative 6h was found to be an inadequate substrate for
this ring-closing reaction, and the starting material was
recovered in 50% yield (entry 8).
instead of the carbonylative 7-methylbicyclo[5.3.0]decenone
derivative (entry 9). Interestingly, compound 12 was not
obtained when 10f was heated for a prolonged time without
the Rh(I) catalyst. Thus, the formation of 12 would tenta-
tively be rationalized by the first isomerization of the double
bond of 10f, followed by the thermal [2 + 2] cycloaddition.16
Coordination of the Rh(I) catalyst with the olefin moiety
would accelerate the conversion of the terminal olefin into
the internal one.
In summary, we have described the novel [RhCl(CO)2]2-
catalyzed intramolecular [2 + 2 + 1] cycloaddition of
3-phenylsulfonyl-1,2,7-octatrienes leading to the formation
of the bicyclo[4.3.0]non-1(9)-en-8-one, in which the distal
double-bond of the allenyl moiety exclusively served as a
π-component. This method not only was shown to be
applicable to the construction of the one-carbon homologated
bicyclo[5.3.0]dec-1(10)-en-9-one skeleton but also provided
a new entry for the construction of the bicyclo[4.3.0]non-
1(9)-en-8-one skeleton having an alkyl appendage at the ring
juncture, which was hardly attained in a satisfactory yield
by the Pauson-Khand reaction of the corresponding enynes.
Determining the scope and limitations of this method as well
as application to the synthesis of natural products are now
in progress.
The application of the newly developed [RhCl(CO)2]2-
catalyzed Pauson-Khand-type [2 + 2 + 1] cycloaddition
of allenenes for the synthesis of the bicyclo[5.3.0]decenones
was the next subject. Exposure of the 1,2,8-nonatriene 10a
to the standard ring-closing conditions (2.5 mol % of [RhCl-
(CO)2]2, 5 atm of CO, 120 °C in toluene) afforded the
bicyclo[5.3.0]decenone derivative 11a in 49% yield as a
mixture10 of the cis- and trans-isomers in the ratio 15:85
(Table 3, entry 1). Increasing both the loading amounts of
the Rh(I) catalyst (5 mol %) and CO pressure (10 atm)
produced an improvement in the chemical yield (73%) (entry
2). Furthermore, 10 mol % of the Rh(I) catalyst under 10
atm of CO provided 11a in 82% yield (entry 3). Compound
10b also furnished the ring-closed product 11b in moderate
yields (entries 4 and 5). However, the simpler 3-phenylsul-
fonylnona-1,2,8-triene (10c) gave the ring-closed product 11c
in a rather low yield (entry 6). The nitrogen atom containing
substrate 10d afforded the corresponding azabicyclo[5.3.0]-
decenone 11d in 73% yield (entry 7), while the oxabicyclo
congener 11e was formed in a low yield (entry 8). The low
yields for compounds 10c,e might be attributable to the loss
of the Thorpe-Ingold-type effects18 compared to those of
other substrates. The 1,1-dialkylalkene derivative 10f unex-
pectedly produced the bicyclo[4.2.0]nonene framework 1219
Acknowledgment. This work was supported in part by
a Grant-in Aid for Scientific Research from the Ministry of
Education, Culture, Sports, Science and Technology, Japan,
for which we are thankful.
Supporting Information Available: General procedures
for the [2 + 2 + 1] cycloaddtion and preparation of
sulfonylallenenes, characterization data for all new com-
(15) A few precedents dealing with the construction of the more
complexed ring-fused cyclic compounds (including a bicyclo[4.3.0]nonenone
framework) from enynes are available. See: (a) Corlay, H.; Fouquet, E.;
Magnier, E.; Motherwell, W. B. Chem. Commun. 1999, 183-184. (b)
Ishizaki, M.; Iwahara, K.; Niimi, Y.; Satoh, H.; Hoshino, O. Tetrahedron
2001, 57, 2729-2738. (c) Magnus, P.; Fielding, M. R.; Wells, C.; Lynch,
V. Tetrahedron Lett. 2002, 43, 947-950.
(16) (a) Padwa, A.; Meske, M.; Murphree, S.; Watterson, S. H.; Ni, Z.
J. Am. Chem. Soc. 1995, 117, 7071-7080. (b) Padwa, A.; Lipka, H.;
Watterson, S. H.; Murphee, S. S. J. Org. Chem. 2003, 68, 6238-6250.
(17) No bicyclo[3.2.0] compounds, such as compound 8, could be
detected except during the reaction of 6f.
1
pounds, and H and 13C NMR spectra for compounds 6d,e,
7b,d,e,g, 10c,e,f, and 11e. This material is available free of
charge via the Internet at http://pubs.acs.org.
OL0600990
(19) Padwa16a reported that the thermolysis of 5,5-bis(methoxycarbonyl)-
3-phenylsulfonylnona-1,2,8-triene and 3,5,5-tris(phenylsulfonyl)nona-1,2,8-
triene in refluxing xylene afforded the monocyclic eight-membered products
in high yields instead of the bicyclo[5.2.0]nonenes.
(18) For a recent review, see: Jung, M. E.; Piizzi, G. Chem. ReV. 2005,
105, 1735-1766.
1220
Org. Lett., Vol. 8, No. 6, 2006