Breaking of the C-C bond of cyclobutanones by rhodium(I) and its extension to catalytic synthetic reactions

Article abstract of DOI:10.1021/ja9604525

A study of rhodium(I)-catalyzed synthetic transformations involving selective breaking of the C-C bond α to the carbonyl group of cyclobutanones is described. Decarbonylation took place on treatment of a cyclobutanone with an equimolar amount of (Ph₃

Full text of DOI:10.1021/ja9604525

J. Am. Chem. Soc. 1996, 118, 8285-8290
8285
Breaking of the C-C Bond of Cyclobutanones by Rhodium(I)
and Its Extension to Catalytic Synthetic Reactions
Masahiro Murakami,* Hideki Amii, Kunji Shigeto, and Yoshihiko Ito*
Contribution from the Department of Synthetic Chemistry and Biological Chemistry,
Kyoto UniVersity, Yoshida, Kyoto 606-01, Japan
ReceiVed February 12, 1996X
Abstract: A study of rhodium(I)-catalyzed synthetic transformations involving selective breaking of the C-C bond
R to the carbonyl group of cyclobutanones is described. Decarbonylation took place on treatment of a cyclobutanone
with an equimolar amount of (Ph3P)3RhCl at reflux in toluene to afford the corresponding cyclopropane. The formation
of the cyclopropane suggests that Rh(I) undergoes an insertion into the bond between the carbonyl carbon and the
R-carbon in the initial step. Catalytic decarbonylation of cyclobutanone was also achieved. The mode and rate of
the reaction depended greatly on the ligands of the rhodium(I) complex. When a cyclobutanone bearing a hydrogen
atom at the 3-position was used, appropriate choice of the catalyst system led to the selective formation of either a
cyclopropane or an alkene. Breaking of the carbon-carbon bond was next combined with hydrogenolysis. When
cyclobutanone was treated under hydrogen pressure with a catalytic amount of a rhodium(I) complex having a bidentate
diphosphine ligand like 1,2-bis(diphenylphosphino)ethane, a ring-opened alcohol was produced in good yield. Selective
breaking of C-C bonds by a soluble transition metal complex is achieved in these practical synthetic processes.
Introduction
consequence, the problem of C-C bond breaking has been
rarely addressed from the viewpoint of synthetic chemistry5d
and remains a challenging topic of considerable scientific and
technological interest. We present here new synthetic processes
which involve selective breaking of the C-C single bond R to
the carbonyl group of cyclobutanones by soluble rhodium(I)
catalysts.8
The use of transition metals has provided a wide repertoire
of transformations in organic synthesis and has recently been
extended into the area of manipulation of considerably inert
organic functionalities.1 For example, aromatic and olefinic
C-H bonds are catalytically cleaved by late transition metal
complexes in synthetic processes.2 Carbon-carbon bonds are
generally even more inert toward transition metals, and hence
activation of C-C bonds has gained intensified interest in the
field of organometallic chemistry. In the petroleum industry,
breaking of C-C bonds has been carried out in the presence of
a heterogeneous catalyst at high temperature. Cleavage, how-
ever, is totally non-selective; long-chain hydrocarbons are cut
into smaller pieces. Under homogeneous conditions, C-C bond
cleavage by a process of insertion of transition metals has been
mostly observed in stoichiometric reactions,3 with substrates
which are designed for this purpose,4 with highly strained
substrates like cyclopropane and cubane,5 or with unsaturated
ketones.6,7 Direct observation of thermodynamically stable
C-C cleaved complexes also has been reported.3f,g,4b,h,5e
However, only a few are catalytic rections.3f,4c,5d,f,7c,e As a
X Abstract published in AdVance ACS Abstracts, August 15, 1996.
(1) For review, see: Crabtree, R. H. Chem. ReV. 1985, 85, 245.
(2) (a) Murai, S.; Kakiuchi, F.; Sekine, S.; Tanaka, Y.; Kamatani, A.;
Sonoda, M.; Chatani, N. Nature 1993, 366, 529. (b) Kakiuchi, F.; Sekine,
S.; Tanaka, Y.; Kamatani, A.; Sonoda, M.; Chatani, N.; Murai, S. Bull.
Chem. Soc. Jpn. 1995, 68, 62. (c) Kakiuchi, F.; Tanaka, Y.; Sato, T.;
Chatani, N.; Murai, S. Chem. Lett. 1995, 679. (d) Kakiuchi, F.; Yamamoto,
Y.; Chatani, N.; Murai, S. Chem. Lett. 1995, 681. (e) Lim, Y.-G.; Kim, Y.
H.; Kang, J.-B. J. Chem. Soc., Chem. Commun. 1994, 2267. (f) Williams,
N. A.; Uchimaru, Y.; Tanaka, M. J. Chem. Soc., Chem. Commun. 1995,
1129. (g) Trost, M.; Imi, K.; Davies, I. W. J. Am. Chem. Soc. 1995, 117,
5371 and references therein.
Results and Discussion
Rhodium-Mediated Decarbonylation of Cyclobutanones.
Cyclobutanone 1 was treated with an equimolar amount of
(Ph3P)3RhCl at reflux in toluene for 41 h. Decarbonylation took
place to afford quantitatively the corresponding cyclopropane
4 along with trans-[Rh(CO)Cl(PPh3)2] (5).9 The formation of
4 and 5 suggests that Rh(I) undergoes an insertion into the bond
between the carbonyl carbon and the R-carbon, giving the
(4) (a) Suggs, J. W.; Cox, S. D. J. Organomet. Chem. 1981, 221, 199.
(b) Suggs, J. W.; Jun, C.-H. J. Am. Chem. Soc. 1984, 106, 3054. (c) Suggs,
J. W.; Jun, C.-H. J. Chem. Soc., Chem. Commun. 1985, 92. (d) Suggs, J.
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Nature 1994, 370, 42. (g) Liou, S.-Y.; Gozin, M.; Milstein, D. J. Chem.
Soc., Chem. Commun. 1995, 1965. (h) Liou, S.-Y.; Gozin, M.; Milstein,
D. J. Am. Chem. Soc. 1995, 117, 9774.
(5) (a) Bishop, K. C. Chem. ReV. 1976, 76, 461. (b) Tipper, C. F. H. J.
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R. G. J. Am. Chem. Soc. 1986, 108, 7346. (f) Fujimura, T.; Aoki, S.;
Nakamura, E. J. Org. Chem. 1991, 56, 2809 and references therein.
(6) Alkynyl ketones: Mu¨ller, E.; Segnitz, A. Liebigs Ann. Chem. 1973,
1583.
(7) Diketones: (a) Kolomnikov, I. S.; Svoboda, P.; Vol’pin, M. E. IzV.
Akad. Nauk. Ser. SSSR 1972, 2818; Chem. Abstr. 1973, 78, 97789k. (b)
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1991, 113, 2771. (f) Huffman, M. A.; Liebeskind, L. S. Organometallics
1992, 11, 255.
(3) (a) Schott, A.; Schott, H.; Wilke, G.; Brandt, J.; Hoberg, H.;
Hoffmann, E. G. Liebigs Ann. Chem. 1973, 508. (b) Crabtree, R. H.; Dion,
R. P. J. Chem. Soc., Chem. Commun. 1984, 1260. (c) Crabtree, R. H.;
Dion, R. P.; Gibboni, D. J.; McGrath, D. V.; Holt, E. M. J. Am. Chem.
Soc. 1986, 108, 7222. (d) Hartwig, J. F.; Anderson, R. A.; Bergman, R.
G. J. Am. Chem. Soc. 1989, 111, 2717. (e) Bennett, M. A.; Nicholls, J. C.;
Rahman, A. K. F.; Redhouse, A. D.; Spencer, J. L.; Willis, A. C. J. Chem.
Soc., Chem. Commun. 1989, 1328. (f) Perthuisot, C.; Jones, W. D. J. Am.
Chem. Soc. 1994, 116, 3647. (g) Suzuki, H.; Takaya, Y.; Takemori, T. J.
Am. Chem. Soc. 1994, 116, 10779. (h) Jun, C.-H.; Kang, J.-B.; Lim, Y.-
G. Tetrahedron Lett. 1995, 36, 277.
(8) A preliminary communication: Murakami, M.; Amii, H.; Ito, Y.
Nature 1994, 370, 540.
(9) (a) Evans, D.; Osborn, J. A.; Wilkinson, G. Inorg. Synth. 1968, 11,
99. (b) Tsuji, J.; Ohno, K. Tetrahedron Lett. 1965, 3969.
S0002-7863(96)00452-0 CCC: $12.00 © 1996 American Chemical Society

8286 J. Am. Chem. Soc., Vol. 118, No. 35, 1996
Murakami et al.
most frequently used as a stoichiometric decarbonylation
reagent. Due to the high cost of rhodium, however, a catalytic
reaction would be genuinely more useful.7c,11
In contrast to the reactions of acyl halides and aldehydes,
examples of transition metal-mediated decarbonylation of
ketones have been limited to alkynyl ketones,6 diketones,7c or
ketones used as solvent.12 This is probably due to the increased
difficulty of insertion of a transition metal into the R C-C bond.
We next examined the rhodium catalyst in detail in order to
make the present decarbonylation reaction catalytic in rhodium.
Catalytic Decarbonylation of Cyclobutanones. A model
cyclobutanone (12), carrying a hydrogen atom at the 3-position,
was heated in xylene in the presence of 5 mol % of a variety of
rhodium(I) complexes listed in Table 1. Although very slowly,
decarbonylation occurred on treatment of 12 with trans-[Rh-
(CO)Cl(PPh3)2] in refluxing xylene (137-144 °C), yielding a
decarbonylated cyclopropane (13) together with a ring-opened
alkene (14) (runs 1 and 2). It is likely that expulsion of carbon
monoxide from rhodium occurred at the refluxing temperature
of xylene to regenerate an active rhodium species with a vacant
coordination site. When neutral Rh(I) complexes prepared in
situ by mixing a dinuclear complex [Rh2(cod)2Cl2] (cod ) 1,5-
cyclooctadiene) with bidentate diphosphines like Ph2P(CH2)3-
PPh2 (dppp) and Ph2P(CH2)4PPh2 (dppb) in a molar ratio of
1:2 were used, a significant increase in the rate of decarbony-
lation was observed, and moreover, alkene formation was
exclusively favored (runs 3 and 4). It may be assumed that cis
chelation gives the rhodium better chance to undergo insertion
into the R-bond of 12. The cationic complex [Rh(dppe)2]Cl
(dppe ) Ph2P(CH2)2PPh2), an especially active catalyst for
decarbonylation of aldehydes,11b was not as effective for
cyclobutanone (12), probably due to steric reasons (run 5).
Another cationic complex having one dppb ligand per rhodium,
[Rh(cod)(dppb)]BF4, caused not only decarbonylation, but
further double bond migration of the terminal alkene (14) to an
inner one (15) (run 6). On the contrary, the formation of the
alkene (14) was suppressed by replacing phosphine ligands of
a neutral rhodium complex with arsine ligands. Decarbonylation
of 12 proceeded gradually with a high cyclopropane/alkene ratio
(run 7). Thus, appropriate choice of the catalyst system led to
the selective formation of either a cyclopropane or an alkene.
The two catalytic systems for decarbonylation were applied
to other cyclobutanones which also bore a hydrogen atom at
the 3-position. Whereas a neutral complex prepared in situ from
[Rh2(cod)2Cl2] and dppp effected selective conversion of the
cyclobutanone (16) to the alkene (18), the Rh-AsPh3 system
favored the formation of the cyclopropane (17). Cyclopropane
4 was analogously produced from the bicyclic substrate 1 by
the use of a catalytic amount of rhodium. However, no alkene
formation was observed even with use of the Rh-dppb system.
It seems that â elimination with the hydrogen at a bridgehead
carbon is unfavorable.
5-membered cyclic acylrhodium 2 in the initial step. Then, the
carbonyl group is extruded from the 5-membered ring, with the
carbon atom next to the carbonyl carbon migrating onto rhodium
to furnish the contracted 4-membered rhodacycle 3. Subsequent
reductive elimination gives rise to cyclopropane 4 together with
the rhodium carbonyl complex 5. When 10 mol % of (Ph3P)3-
RhCl was used, only 10% of cyclopropane 4 was obtained. The
decarbonylation reaction failed to occur on treatment with trans-
[Rh(CO)Cl(PPh3)2] at reflux in toluene. It is likely that the
binding of carbon monoxide to rhodium in trans-[Rh(CO)Cl-
(PPh3)2] is so strong that regeneration of an active rhodium
species possessing a vacant coordination site by CO expulsion
fails to occur at the refluxing temperature of toluene (Vide infra).
Cyclobutanone (6) underwent an analogous decarbonylation
on treatment with an equimolar amount of (Ph3P)3RhCl to afford
cyclopropane 7 in 80% yield.
Cyclopentanone (8) which is much less strained than cy-
clobutanone (1) also underwent the rhodium-mediated decar-
bonylation to give cyclobutane (9), although less efficiently.
Decarbonylation of cyclododecanone (10) required higher
temperature by the use of benzonitrile as the solvent. These
results disclose the potential reactivity of rhodium(I) to insert
into the C-C single bond R to the carbonyl group of cyclic
ketones.
Next, decarbonylation of a cyclobutanone (19), lacking the
possibility of â-hydride elimination due to the absence of a
Thus, cyclic ketones were decarbonylated by the action of a
stoichiometric amount of RhCl(PPh3)3. In organic reactions, a
carbonyl functionality acts as an activating and/or directing
group. Elaboration of an organic molecule is often carried out
on the basis of a carbonyl group, which may ultimately be
removed from the carbon skeleton. In this context, decarbon-
ylation reactions are of synthetic value. Decarbonylation of acyl
halides and aldehydes has been known to occur under homo-
geneous conditions, affording the corresponding alkyl halides
and alkanes, respectively.9b,10 The first step is considered to
involve insertion of a transition metal into the carbon-halogen
or carbon-hydrogen bond. Wilkinson’s complex is by far the
(10) (a) Colquhoun, H. M.; Thompson, D. J.; Twiggs, M. V. Carbony-
lation: Direct Synthesis of Carbonyl Compounds; Plenum: New York, 1991;
pp 205-225. (b) Tkatchenko, T. In ComprehensiVe Organometallic
Chemistry; Wilkinson, S. G. R., Stone, F. G. A., Abel, E. W., Eds.;
Pergamon: Oxford, 1981; Vol. 8, pp 214-219. (c) Bates, R. W. In
ComprehensiVe Organometallic Chemistry II; Abel, E. W., Stone, F. G.
A., Wilkinson, G., Eds.; Pergamon: Oxford, 1995; Vol. 12 (Hegedus, L.
S., Vol. Ed.); pp 373-378.
(11) For catalytic decarbonylation, see: (a) Ohno, K.; Tsuji, J. J. Am.
Chem. Soc. 1968, 90, 99. (b) Doughty, D. H.; Pignolet, L. H. J. Am. Chem.
Soc. 1978, 100, 7083. (c) Grunewald, G. L.; Davis, D. P. J. Org. Chem.
1978, 43, 3074. (d) O’Connor, J. M.; Ma, J. J. Org. Chem. 1992, 57, 5075.
(e) Obora, Y.; Tsuji, Y.; Kawamura, T. J. Am. Chem. Soc. 1995, 117, 9814.
(12) Rusina, A.; Vlcˇek, A. Nature 1965, 208, 295.

Breaking of the C-C Bond of Cyclobutanones by Rh(I)
Table 1. Rh(I)-Catalyzed Decarbonylation of Cyclobutanone 12
J. Am. Chem. Soc., Vol. 118, No. 35, 1996 8287
a Isolated yield unless specified. b Approximate yield based on reactant-products distribution determined by GC analysis.
from the 5-membered cyclic acylrhodium or regenerated via
insertion of rhodium into the produced cyclopropane. The latter
possibility was confirmed by the reaction of the isolated
cyclopropane (13) with a catalytic amount of [Rh(cod)(dppb)]-
BF4.
hydrogen atom at the 3-position, was examined using cationic
complexes, which were expected to loosen a coordinating CO
ligand more easily than neutral complexes owing to decreased
Rh-CO back-bonding. Interestingly, the activity depended
greatly on the type of phosphine ligand; bidentate ligands dppb
and dppp were far superior to dppe and PPh3. The wider bite
angles ( P-Rh-P) of dppb and dppp than that of dppe might
favor the expulsion of carbon monoxide from rhodium.13
Treatment of 19 with [Rh(cod)(dppb)]BF4 or [Rh(cod)(dppp)]-
BF4 in refluxing xylene for 24 h produced cyclopropane 20
quantitatively. Cyclobutanone (21) was also catalytically de-
carbonylated, giving cyclopropane 22 in 77% yield. Catalytic
decarbonylation of other strain-free cycloalkanones like cyclo-
pentanone has been unsuccessful so far.
There are two possible routes from a 5-membered cyclic
acylrhodium to an alkene. â-Hydride elimination can take place
with a 5-membered cyclic acylrhodium or a rhodacyclobutane
intermediate. The rhodacyclobutane may be directly formed
(13) The ligand flexibility has been proposed to be responsible for the
rate acceleration with dppp as compared with dppe.11b

8288 J. Am. Chem. Soc., Vol. 118, No. 35, 1996
Murakami et al.
Table 2. Rhodium-Catalyzed Hydrogenolysis of 1a
Hydrogenolysis of Cyclobutanones. Selective carbon-
carbon bond breaking at the R-position of a carbonyl group by
a soluble rhodium complex is a key feature of the decarbony-
lation reaction mentioned above. We next explored a synthetic
reaction wherein the carbonyl carbon is retained in the final
product, and thus, breaking of a carbon-carbon bond was
combined with a process of hydrogenolysis.14 When cyclo-
butanone 1 was treated under a hydrogen atmosphere (20 atm)
with 1 equiv of (Ph3P)3RhCl at 130 °C for 5 days in toluene in
an autoclave, alcohol 24 was produced in 47% yield together
with cyclopropane 4 (35%) and a ring-opened hydrocarbon 25
(15%). It is likely that the aldehyde 23 is primarily formed
run
bidentate diphosphine
24, %
4 + 25, %
1
2
3
4
5
dppm
dppe
dppp
dppb
dppf
23
87
82
20
31
5
10
10
40
18
a A mixture of cyclobutanone 1 [Rh2(cod)2Cl2] (5 mol %) and a
bidentate diphosphine (12 mol %) in toluene under H2 (50 atom) was
heated at 140 °C for 2 days. Then, the reaction mixture was reduced
with NaBH4.
after reducing the reaction mixture with NaBH4 (runs 2 and 3).
Other bidentate ligands like bis(diphenylphosphino)methane
(dppm), dppb, and 1,1′-bis(diphenylphosphino)ferrocene (dppf)
afforded less active catalysts and produced a significant amount
of decarbonylated compounds (4 and 25). It was also found
that the hydrogenolysis proceeded slightly faster in THF than
in toluene.
By the use of a catalytic amount of a Rh(I) complex prepared
in situ from [Rh2(cod)2Cl2] and dppe, various cyclobutanones
underwent hydrogenolysis of the C-C single bond R to the
carbonyl group (Table 3). In runs 2-4, a mixture of an alcohol
and an aldehyde was obtained and subsequently treated with
NaBH4 to obtain the product as the alcohol. Alcohols including
synthetically useful compounds like 3-methylundecanol 30 (a
synthetic building block of an insect pheromone)15 and 2-methyl-
1,4-butanediol derivative 31 (a bifunctional isoprenoid building
block)16 were isolated in good yields. Cyclobutanones pos-
sessing a substituent at the 2- and 3-positions underwent facile
hydrogenolysis. Although the reaction proceeded also with 3,3-
disubstituted cyclobutanone (runs 8 and 9), hydrogenolysis of
2,2-disubstituted cyclobutanone was sluggish, probably due to
steric reasons (run 10). The bond to the less-substituted R
carbon atom was selectively cleaved in the reactions of
unsymmetric cyclobutanones (runs 7, 8, and 10). Ether, ester,
and Cl-arene functionalities were compatible with the present
reaction conditions. Thus, catalytic hydrogenolysis of C-C
single bonds is accomplished via Rh(I)-mediated breaking of
the C-C bond under a hydrogen atmosphere. The addition of
dihydrogen together with relief of the structural strain of the
cyclobutanone skeleton may make a large contribution to the
driving force of this catalytic reaction.
through the addition of dihydrogen to a 5-membered cyclic
acylrhodium and the subsequent reductive elimination. The
following second addition of dihydrogen to 23 gives the alcohol
24. The ring-opened hydrocarbon 25 is formed presumably by
hydrogenation of the rhodacyclobutane. The formation of
cyclobutanol 26 was not observed, indicating that breaking of
the C-C bond proceeds faster than direct hydrogenation of the
carbonyl group under the present conditions. Moreover, there
was no formation of alcohol 27. These results show that the
insertion of rhodium(I) took place selectively into the less-
substituted C-C bond R to the carbonyl group of 1. During
this hydrogenolysis, the original carbonyl group 1 is retained
as a hydroxymethyl group in the product 24.
The effect of phosphine ligands was examined in order to
make the reaction catalytic. The use of trialkylphosphine instead
of triphenylphosphine gave inferior results in terms of reaction
rate as well as product distribution. The rhodium(I) complexes
prepared in situ from [Rh2(cod)2Cl2] and bidentate diphosphine
ligands were found to be more effective catalysts. As listed in
Table 2, the chain length between the two diphenylphosphino
groups was important. When dppe or dppp was used as the
ligand, the ring-opened alcohol (24) was obtained in good yield
Conclusion
A number of excellent methods are currently available for
the synthesis of cyclobutanones.17 In particular, [2 + 2]
cycloaddition reaction of alkenes with ketene derivatives
provides a simple and general approach to those compounds,
often with control of the regio- and stereochemistry of ring
substituents. Therefore, if coupled with the preparation of
cyclobutanones from alkenes, the synthetic processes described
herein achieve selective manipulations of C-C double bonds
as formulated below; the internal sp2 carbon of a terminal olefin
is regioselectively methylated by preparation of a cyclobutanone
(15) Larcheveque, M.; Sanner, C.; Azerad, R.; Buisson, D. Tetrahedron
1988, 44, 6407.
(16) Schmid, R.; Hansen, H.-J. HelV. Chim. Acta 1990, 73, 1258.
(17) (a) Hyatt, J. A.; Raynolds, P. W. In Organic Reactions; Joyce, R.
M., Ed.; Wiley: New York, 1994; Vol. 45, Chapter 2. (b) Krepski, L. R.;
Hassner, A. J. Org. Chem. 1978, 43, 2879. (c) Bak, D. A.; Brady, W. T.
J. Org. Chem. 1979, 44, 107. (d) Gadwood, R. C.; Mallick, I. M.; DeWinter,
A. J. J. Org. Chem. 1987, 52, 774. (e) Trost, B. M. In Topics in Current
Chemistry, Vol. 133: Small Ring Compounds in Organic Synthesis I; de
Meijere, A., Ed.; Springer-Verlag: Berlin, 1986; pp 3-82. (f) Salau¨n, J.
R. Y. In Topics in Current Chemistry, Vol. 144: Small Ring Compounds in
Organic Synthesis III; de Meijere, A., Ed.; Springer-Verlag: Berlin, 1988;
pp 1-71 and references therein.
(14) Hydrogenolysis of the C-C bond of a ring-strained bicyclic â-lactam
occurs in the presence of heterogeneous Pd: Konosu, T.; Oida, S. Chem.
Pharm. Bull. 1992, 40, 609.

Breaking of the C-C Bond of Cyclobutanones by Rh(I)
J. Am. Chem. Soc., Vol. 118, No. 35, 1996 8289
Table 3. Rhodium(I)-Catalyzed Hydrogenolysis of Cyclobutanones
insertion of rhodium(I) into the R C-C bond, the reactions
described here present examples of practical synthetic trans-
formations involving selective breaking of C-C bonds by
transition metal complexes under homogeneous conditions. The
present study suggests that the insertion of a transition metal
into the C-C bond R to a carbonyl group may be a kinetically
feasible, fundamental process. Fine-tuning of the ligand set,
the most favorable feature of homogeneous catalysts, and
designing a reaction to gain a thermodynamic driving force
would lead to the development of various kinds of transforma-
tions, hopefully including those which can be applied to natural
product syntheses.
Experimental Section
General. Column chromatography was performed with silica gel
(Wakogel C-200). Preparative thin-layer chromatography (TLC) was
performed with silica gel 60 PF254 (E. Merck, Darmstadt). 1H and 13
C
NMR spectra were acquired in chloroform-d at 200 and 50 MHz,
respectively. Na2SO4 was used to dry organic layers after extraction.
Materials were obtained from commercial sources unless otherwise
noted. THF was distilled from sodium diphenylketyl, toluene from
LiAlH4, and xylene (an isomers mixture) from CaH2. Cyclobutanones
were prepared by [2 + 2] cycloaddition of alkenes with dichloroketene
and the following dechlorination with zinc.17a
2-Phenylbicyclo[4.1.0]heptane (4). A toluene solution (2 mL) of
(Ph3P)3RhCl (23.2 mg, 25 µmol) and 1 (5.0 mg, 25 µmol) was heated
at reflux for 41 h under an argon atmosphere. The cooled reaction
mixture was filtered through a pad of florisil and the filtrate was purified
by preparative thin layer chromatography of silica gel (hexane) to afford
4 (4.3 m, 99%) as a colorless oil: 1H NMR δ 0.14-0.30 (m, 1 H),
0.60-0.80 (m, 1 H), 0.80-1.40 (m, 4 H), 1.40-1.80 (m, 2 H), 1.80-
2.00 (m, 2 H), 2.75-2.90 (m, 1 H), 7.10-7.40 (m, 5 H); 13C NMR δ
10.4, 10.6, 16.1, 18.7, 23.2, 31.9, 42.2, 125.6, 127.6, 128.2, 149.1;
HRMS calcd for C13H16 (m/z) 172.1248, found 172.1242.
Octylcyclopropane (7). By a procedure similar to that for 4 (column
chromatography, hexane), the title compound (6.1 mg, 80%) was
obtained from 6 (9.0 mg, 50 µmol) and (Ph3P)3RhCl (46.3 mg, 50
µmol).
2-Phenylbicyclo[4.2.0]octane (9). By a procedure similar to that
for 4 (thin layer chromatography, hexane:AcOEt ) 5:1), the title
compound (10.6 mg, 57%) was obtained as a colorless oil from 8 (21.4
mg, 100 µmol) and (Ph3P)3RhCl (92.4 mg, 100 µmol). 1H NMR δ
1.2-2.0 (m, 10 H), 2.1-2.4 (m, 2 H), 2.6-2.8 (m, 1 H), 7.1-7.4 (m,
5 H); 13C NMR δ 20.7, 21.3, 24.2, 25.0, 32.0, 33.0, 39.0, 47.1, 125.8,
127.8, 128.3, 148.5; HRMS calcd for C14H18 (m/z) 184.1404, found
184.1404.
Cycloundecane (11). A benzonitrile solution (1 mL) of (Ph3P)3-
RhCl (27.7 mg, 30 µmol) and 7 (5.5 mg, 30 µmol) was heated at 150
°C for 3 days under an argon atmosphere. A workup procedure similar
to that for 4 (column chromatography, hexane) afforded 11 (1.0 mg,
22%). 1H NMR δ 1.42 (s, 22 H); 13C NMR δ 26.3; HRMS calcd for
C11H22 (m/z) 154.1716, found 154.1722.
a Isolated yield. b After hydrogenolysis, the reaction mixture was
treated with NaBH4. c Toluene was used as the solvent.
and the following decarbonylation. Analogously, the rhodium-
catalyzed hydrogenolysis accomplished regio- and stereoselec-
tive syn 1,2-addition of methyl and hydroxymethyl groups to
C-C double bonds.
Hexadecylcyclopropane (13). A xylene solution (2 mL) of
[Rh2(cod)2Cl2] (1.2 mg, 2.5 µmol), AsPh3 (3.1 mg, 10 µmol), and 12
(29.4 mg, 0.10 mmol) was heated at reflux for 7 days under an argon
atmosphere. A workup procedure similar to that for 4 (column
chromatography, hexane) afforded a mixture of 13 and 14 (18.6 mg,
13:14 ) 97:3) as a colorless oil. The following NMR data are those
for 13: 1H NMR δ -0.06-0.04 (m, 2 H), 0.32-0.45 (m, 2 H), 0.55-
0.74 (m, 1 H), 0.89 (t, J ) 6.5 Hz, 3 H), 1.10-1.50 (m, 30 H); 13C
NMR δ 4.3, 10.9, 14.1, 22.7, 29.3, 29.5, 29.7, 31.9, 34.8. Anal. Calcd
for C19H38: C 85.63; H, 14.37. Found: C, 85.36; H, 14.21.
2-Methyl-1-octadecene (14). A xylene solution (1 mL) of [Rh2(cod)2-
Cl2] (1.2 mg, 2.5 µmol), dppp (2.5 mg, 6 µmol), and 12 (29.4 mg,
0.10 mmol) was heated at reflux for 10 h under an argon atmosphere.
A workup procedure similar to that for 4 (column chromatography,
hexane) afforded 14 (27.0 mg, 99%) as a colorless oil: 1H NMR δ
0.88 (t, J ) 6.5 Hz, 3 H), 1.10-1.40 (m, 28 H), 1.71 (s, 3 H), 2.00 (t,
J ) 7.4 Hz, 2 H), 4.60-4.70 (m, 2 H); 13C NMR δ 14.1, 22.4, 22.7,
Although we have no experimental or theoretical result to
provide a basis for an argument for the mechanism of the

8290 J. Am. Chem. Soc., Vol. 118, No. 35, 1996
Murakami et al.
27.7, 29.4, 29.6, 31.9, 37.9, 109.5, 146.4; IR (neat) 1654 cm-1. Anal.
Calcd for C19H38: C, 85.63; H, 14.37. Found: C, 85.64; H, 14.65.
4-Cyclopropylbutyl Benzoate (17). By a procedure similar to that
for 13, the title compound (30.6 mg, 70%) was obtained from 16 (49.2
mg, 0.20 mmol), [Rh2(cod)2Cl2] (2.5 mg, 5 µmol), and AsPh3 (7.3 mg,
24 µmol): 1H NMR δ -0.01-0.10 (m, 2 H), 0.26-0.50 (m, 2 H),
0.58-0.80 (m, 1 H), 1.20-1.40 (m, 2 H), 1.50-1.70 (m, 2 H), 1.70-
1.90 (m, 2 H), 4.32 (t, J ) 6.6 Hz, 2 H), 7.40-7.60 (m, 3 H), 8.00-
8.10 (m, 2 H); 13C NMR δ 4.4, 10.7, 26.1, 28.6, 34.3, 65.1, 128.3,
60.9, 128.3, 128.5, 131.6, 145.3; HRMS calcd for C10H13OCl (m/z)
184.0652, found 186.0662.
3-Methyl-1-undecanol (30). A THF solution (3 mL) of [Rh2(cod)2-
Cl2] (4.9 mg, 10 µmol), dppe (9.6 mg, 24 µmol), and 3-octylcyclo-
butanone (36 mg, 0.2 mmol) under a hydrogen atmosphere (50 atm)
in an autoclave was heated at 140 °C for 3 days. A workup procedure
similar to that for 29 (column chromatography, hexane:Et2O ) 2:1)
afforded 30 (29.5 mg, 80%) as a colorless oil.
3-Methyl-4-phenoxy-1-butanol (31). A toluene solution (5 mL)
of [Rh2(cod)2Cl2] (14.8 mg, 30 µmol), dppe (28.6 mg, 72 µmol), and
3-(phenoxymethyl)cyclobutanone (106 mg, 0.60 mmol) under a hy-
drogen atmosphere (50 atm) in an autoclave was heated at 140 °C for
42 h. A workup procedure similar to that for 29 (thin layer
chromatography, hexane:AcOEt ) 2:1) afforded 31 (76.9 mg, 71%)
as a pale yellow oil: 1H NMR δ 1.07 (d, J ) 6.8 Hz, 3 H), 1.5 (br s,
1 H), 1.5-1.7 (m, 1 H), 1.7-1.9 (m, 1 H), 2.1-2.3 (m, 1 H), 3.7-3.9
(m, 2 H), 3.83 (d, J ) 6.4 Hz, 2 H), 6.8-7.0 (m, 3 H), 7.2-7.4 (m, 2
H); 13C NMR δ 17.2, 30.3, 36.9, 60.8, 73.0, 114.5, 120.6, 129.4, 158.9.
Anal. Calcd for C11H16O2: C, 73.30; H, 8.95. Found: C, 73.02; H,
9.07.
129.5, 130.5, 132.8, 166.7; IR (neat) 1724 cm-1
. Anal. Calcd for
C14H18O2: C, 77.03; H, 8.31. Found: C, 76.86; H, 8.38.
5-Methyl-5-hexenyl Benzoate (18). By a procedure similar to that
for 14, the title compound (18.8 mg, 86%) was obtained from 16 (24.6
mg, 0.10 mmol), [Rh2Cl2(cod)2] (1.2 mg, 2.5 µmol), and dppp (2.5
mg, 6 µmol): 1H NMR δ 1.50-1.90 (m, 4 H), 1.73 (s, 3 H), 2.10 (t,
J ) 7.3 Hz, 2 H), 4.34 (t, J ) 6.4 Hz, 2 H), 4.71 (s, 1 H), 4.73 (s, 1
H), 7.35-7.60 (m, 3 H), 7.95-8.10 (m, 2 H); 13C NMR δ 22.3, 23.9,
28.3, 37.3, 64.9, 110.2, 128.3, 129.5, 130.4, 137.8, 145.4, 166.7; IR
(neat) 1724 cm-1
. Anal. Calcd for C14H18O2: C, 77.03, H, 8.31.
Found: C, 77.13; H, 8.28.
1,1-Dibenzylcyclopropane (20). A xylene solution (1 mL) of [Rh-
(cod)(dppb)]BF4 (3.6 mg, 5 µmol) and 19 (25.0 mg, 0.10 mmol) was
heated at reflux for 24 h under an argon atmosphere. A workup
procedure similar to that for 4 (column chromatography, hexane)
afforded 20 (22.2 mg, 99%) as a colorless oil: 1H NMR δ 0.53 (s, 4
H), 2.57 (s, 4 H), 7.10-7.40 (m, 10 H); 13C NMR δ 10.7, 20.8, 41.6,
126.0, 128.0, 129.5, 140.1. Anal. Calcd for C17H18: C, 91.84; H, 8.16.
Found: C, 91.96; H, 8.34.
3-Methyl-5-phenoxypentanol (32). A THF solution (3 mL) of
[Rh2(cod)2Cl2] (2.5 mg, 5.0 µmol), dppe (12.0 mg, 10 µmol), and 3-(2-
phenoxyethyl)cyclobutanone (19.0 mg, 0.10 mmol) under a hydrogen
atmosphere (50 atm) in an autoclave was heated at 140 °C for 60 h. A
workup procedure similar to that for 24 (thin layer chromatography,
hexane:AcOEt ) 2:1) afforded 32 (16.1 mg, 83%) as a colorless oil:
1H NMR δ 0.99 (d, J ) 6.5 Hz, 3 H), 1.4-2.0 (m, 6 H), 3.6-3.8 (m,
2 H), 3.9-4.1 (m, 2 H), 6.8-7.0 (m, 3 H), 7.2-7.4 (m, 2 H); 13C
NMR δ 19.7, 26.8, 36.2, 39.8, 61.0, 65.9, 114.5, 120.6, 129.4, 160.0.
Anal. Calcd for C12H18O2: C, 79.14; H, 9.34. Found: C, 74.04; H,
9.50.
7-Hydroxy-5-methylheptyl Benzoate (33). A THF solution (1 mL)
of [Rh2(cod)2Cl2] (1.3 mg, 2.6 µmol), dppe (2.4 mg, 6.0 µmol), and
3-[4-(benzoyloxy)butyl]cyclobutanone (24.6 mg, 0.10 mmol) under a
hydrogen atmosphere (50 atm) in an autoclave was heated at 140 °C
for 48 h. A workup procedure similar to that for 24 (thin layer
chromatography, hexane:AcOEt ) 2:1) afforded 33 (17.8 mg, 71%)
as a colorless oil: 1H NMR δ 0.91 (d, J ) 6.5 Hz, 3 H), 1.1-2.0 (m,
10 H), 3.55-3.80 (m, 2 H), 4.32 (t, J ) 6.6 Hz, 2 H), 7.3-7.6 (m, 3
H), 7.9-8.0 (m, 2 H); 13C NMR δ 19.5, 23.4, 28.9, 29.4, 36.7, 39.8,
61.1, 65.0, 128.3, 129.5, 130.5, 132.8, 166.7. Anal. Calcd for
C15H22O3: C, 71.97; H, 8.86. Found: C, 72.08; H, 8.96.
2,2-Dimethyl-1-(hydroxymethyl)cyclohexane (34). A toluene solu-
tion (5 mL) of [Rh2(cod)2Cl2] (12.3 mg, 25 µmol), dppe (23.9 mg, 60
µmol), and 1-methyl-cis-bicyclo[4,2,0]octan-7-one (138 mg, 1.0 mmol)
under a hydrogen atmosphere (50 atm) in an autoclave was heated at
140 °C for 3 days. A workup procedure similar to that for 24 (column
chromatography, hexane:Et2O ) 1:1) afforded 34 (104 mg, 74%) as a
colorless oil.
3-Benzyl-3-methyl-4-phenyl-1-butanol (35). A toluene solution
(5 mL) of [Rh2(cod)2Cl2] (4.9 mg, 19 µmol), dppe (9.6 mg, 24 µmol),
and 3,3-dibenzylcyclobutanone (100 mg, 0.4 mmol) under a hydrogen
atmosphere (50 atm) in an autoclave was heated at 140 °C for 42 h. A
workup procedure similar to that for 24 (thin layer chromatography,
hexane:AcOEt ) 2:1) afforded 35 (85 mg, 84%) as a colorless oil: 1H
NMR δ 0.90 (s, 3 H), 1.56 (t, J ) 7.7 Hz, 2 H), 1.6 (br s, 1 H), 2.65
(s, 4 H), 3.83 (t, J ) 7.7 Hz, 2 H), 7.1-7.4 (m, 10 H); 13C NMR δ
24.0, 37.2, 40.7, 46.8, 59.5, 126.0, 127.8, 130.7, 138.5. Anal. Calcd
for C18H22O: C, 84.99; H, 8.72. Found: C, 84.83; H, 8.75.
2,2-Dimethyl-3-phenyl-1-butanol (36). A THF solution (4 mL)
of [Rh2(cod)2Cl2] (6.2 mg, 13 µmol), dppe (12.0 mg, 30 µmol), and
2,2-dimethyl-3-phenylcyclobutanone (87.0 mg, 0.50 mmol) under a
hydrogen atmosphere (50 atm) in an autoclave was heated at 140 °C
for 60 h. A workup procedure similar to that for 24 (thin layer
chromatography, hexane:AcOEt ) 2:1) afforded 36 (8.2 mg, 9%) as a
colorless oil.
2,2-Dimethyl-1-(phenoxymethyl)cyclopropane (22). By a proce-
dure similar to that for 20 (thin layer chromatography, hexane:Et2O )
10:1), the title compound (17.5 mg, 77%) was obtained from 21 (25.6
mg, 0.10 mmol) and [Rh(cod)(dppb)]BF4 (3.6 mg, 5 µmol): 1H NMR
δ 0.20-0.30 (m, 1 H), 0.60 (dd, J ) 8.6, 4.6 Hz, 1 H), 1.00-1.10 (m,
1 H), 1.12 (s, 6 H), 3.84 (dd, J ) 10.2, 8.3 Hz, 1 H), 4.07 (dd, J )
10.2, 6.5 Hz, 1 H), 6.86-7.00 (m, 3 H), 7.20-7.34 (m, 2 H); 13C NMR
δ 16.2, 18.5, 19.9, 23.2, 27.1, 69.3, 114.7, 120.5, 129.4, 159.2. Anal.
Calcd for C12H16O: C, 81.77; H, 9.15. Found: C, 81.37; H, 9.12.
(1R*,2S*,3R*)-1-(Hydroxymethyl)-2-methyl-3-phenylcyclohex-
ane (24). A toluene solution (4 mL) of [Rh2(cod)2Cl2] (3.7 mg, 7.5
µmol), dppe (6.0 mg, 15 µmol), and 1 (30 mg, 150 µmol) under a
hydrogen atomsphere (50 atm) in an autoclave was heated at 140 °C
for 42 h. The cooled reaction mixture was filtered through a pad of
florisil and the filtrate was purified by preparative thin layer chroma-
tography of silica gel (hexane:AcOEt ) 2:1) to afford 24 (26.5 mg,
87%) as a colorless oil: 1H NMR δ 0.72 (d, J ) 6.3 Hz, 3 H), 1.2-
2.0 (m, 9 H), 2.1-2.3 (m, 1 H), 3.64 (dd, J ) 11.3, 5.2 Hz, 1 H), 3.78
(dd, J ) 11.3, 2.1 Hz, 1 H), 7.1-7.4 (m, 5 H); 13C NMR δ 17.1, 26.2,
29.8, 35.8, 38.2, 46.5, 52.2, 65.9, 125.8, 127.6, 128.3, 146.7. Anal.
Calcd for C14H20O: C, 82.30; H, 9.87. Found: C, 82.24; H, 10.16.
3-Phenyl-1-butanol (28). A THF solution (4 mL) of [Rh2(cod)2-
Cl2] (4.9 mg, 10 µmol), dppe (9.6 mg, 24 µmol), and 3-phenylcyclo-
butanone (29 mg, 0.20 mmol) under a hydrogen atmosphere (50 atm)
in an autoclave was heated at 140 °C for 48 h. A workup procedure
similar to that for 24 (thin layer chromatography, hexane:AcOEt )
2:1) afforded 28 (25.1 mg, 84%) as a colorless oil.
3-(4-Chlorophenyl)-1-butanol (29). A THF solution (5 mL) of
[Rh2(cod)2Cl2] (6.2 mg, 12.5 µmol), dppe (12.0 mg, 30 µmol), and
3-(4-chlorophenyl)cyclobutanone (90 mg, 0.50 mmol) under a hydrogen
atmosphere (50 atm) in an autoclave was heated at 140 °C for 44 h.
The cooled reaction mixture was filtered through a pad of florisil and
the filtrate was condensed under reduced pressure. The residue was
dissolved in MeOH (1 mL) and treated with NaBH4 (19 mg, 0.50
mmol). The mixture was diluted with aqueous HCl (1 N), extracted
with ether, dried, and purified by preparative thin layer chromatography
of silica gel (hexane:AcOEt ) 2:1) to afford 29 (75 mg, 81%) as a
colorless oil: 1H NMR δ 1.25 (d, J ) 7.0 Hz, 3 H), 1.4 (br s, 1 H),
1.7-1.9 (m, 2 H), 2.88 (sextet, J ) 7.0 Hz, 1 H), 3.40-3.65 (m, 2 H),
7.05-7.20 (m, 2 H), 7.20-7.35 (m, 2 H); 13C NMR δ 22.3, 35.8, 40.8,
JA9604525