Chromium(III) octaethylporphyrinato tetracarbonylcobaltate: A highly active, selective, and versatile catalyst for epoxide carbonylation

Article abstract of DOI:10.1021/ja051874u

The development of a highly active and selective porphyrin-based epoxide carbonylation catalyst, [(OEP)Cr(THF)₂][Co(CO)₄] (1; OEP = octaethylporphyrinato; THF = tetrahydrofuran), is detailed. Complex 1 is a separated ion pair compose

Full text of DOI:10.1021/ja051874u

Published on Web 07/16/2005
Chromium(III) Octaethylporphyrinato Tetracarbonylcobaltate:
A Highly Active, Selective, and Versatile Catalyst for Epoxide
Carbonylation
Joseph A. R. Schmidt,1 Emil B. Lobkovsky, and Geoffrey W. Coates*
Contribution from the Department of Chemistry and Chemical Biology, Baker Laboratory,
Cornell UniVersity, Ithaca, New York 14853-1301
Received March 24, 2005; E-mail: gc39@cornell.edu
Abstract: The development of a highly active and selective porphyrin-based epoxide carbonylation catalyst,
[(OEP)Cr(THF)2][Co(CO)4] (1; OEP ) octaethylporphyrinato; THF ) tetrahydrofuran), is detailed. Complex
1 is a separated ion pair composed of a tetracarbonylcobaltate anion and an octahedral chromium porphyrin
complex axially ligated by two THF ligands. Regarding the carbonylation of epoxides to â-lactones, catalyst
1 exhibits excellent turnover numbers (up to 10 000) and turnover frequencies (up to 1670 h-1), with
regioselective carbonyl insertion occurring between the oxygen and the sterically less hindered carbon of
the epoxide substrate. Complex 1 is highly tolerant of nonprotic functional groups, carbonylating an array
of aliphatic and cycloaliphatic epoxides, as well as epoxides with pendant ethers, esters, and amides. With
careful control of reaction conditions in the carbonylation of glycidyl esters, the exclusive production of
either the â- or γ-lactone isomer was achieved. Through analysis of reaction stereochemistry, a mechanism
for the formation of γ-lactone products was proposed. Overall, a broad array of synthetically useful lactones
has been synthesized in a rapid and selective fashion by catalytic carbonylation using [(OEP)Cr(THF)2]-
[Co(CO)4].
currently are produced through fermentation routes15 and
possibly in transgenic plants,16 are targeted as substitutes for
Introduction
The catalytic synthesis of â-lactones is of great interest due
to the broad utility of these molecules in organic2 and polymer
chemistry,3 as well as in natural product synthesis.4,5 The
energetically favored ring opening of four-membered lactones
fuels a wide selection of subsequent reactions.2 For example,
nucleophilic attack at the carbonyl moiety results in cleavage
of the acyl oxygen bond, which can then be trapped by an
electrophile to attach two functional groups in one ring-opening
reaction.2 Reaction at the â-carbon of the lactone can be
achieved using organometallic nucleophiles, providing for the
synthesis of a range of carboxylic acids derived from carbon-
oxygen bond scission.6-8 Additional organic reaction pathways
include syn-decarboxylation and enolate reactions.2 The ring-
opening polymerization of â-lactones by metal alkoxide catalysts
gives high molecular weight poly(hydroxyalkanoate)s with
narrow polydispersity.9-14 These biodegradable polymers, which
petroleum-derived materials.3,17 The presence of the â-lactone
moiety in numerous natural products and pharmaceuticals4
demands the development of effective routes for its installation
into complicated, highly functionalized molecules.
An attractive route to synthetically valuable â-lactones is the
ring-expansive carbonylation of epoxides. The catalytic carbo-
nylation of cyclic ethers has been studied for over half a century.
Reppe first reported the carbonylation of tetrahydrofuran in the
presence of water to give adipic acid.18 Eisenmann et al., as
well as Heck, reported the carboxymethylation of epoxides using
cobalt catalysts in the presence of CO and alcohols.19,20 Recent
efforts in this field derive from the milestone achievements
(10) Kurcok, P.; Kowalczuk, M.; Hennek, K.; Jedlinski, Z. Macromolecules
1992, 25, 2017-2020.
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(1) Present address: Department of Chemistry MS 602, The University of
Toledo, 2801 W. Bancroft St., Toledo, OH 43606-3390.
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Microbiol. 1995, 41, 274-281.
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Soc. 2002, 124, 15239-15248.
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J. AM. CHEM. SOC. 2005, 127, 11426-11435
10.1021/ja051874u CCC: $30.25 © 2005 American Chemical Society

Chromium(III) Octaethylporphyrinato Tetracarbonylcobaltate
A R T I C L E S
Scheme 1. Postulated Mechanism of Epoxide Carbonylation
reported by Drent and Kragtwijk in 1994, involving the use of
Co2(CO)8 and 3-hydroxypyridine to effect the carbonylation of
epoxides to form â-lactones and polyester oligomers21 under
high pressures of carbon monoxide.22,23 Alper and co-workers
have shown that by the combination of BF3‚OEt2, a neutral
Lewis acid, with [PPN][Co(CO)4] (PPN ) Ph3PdN+dPPh3)
in dimethoxyethane, substantial rate enhancements could be
achieved.24 Alper applied this system to the carbonylation of a
number of simple epoxides, providing the first demonstration
of the versatility of this reaction. More recently, contributions
from Rieger and co-workers have focused on empirical and
theoretical studies employing a number of simple Lewis acids,
with experimental observations limited to the carbonylation of
propylene oxide.25-27 Exploration of the energies of the ground-
and transition-state structures using density functional theory
(DFT) has helped to confirm the mechanism of epoxide
carbonylation.26 In the last three years, we have developed well-
defined catalysts of the form [Lewis acid][Co(CO)4] for the
carbonylation of epoxides and aziridines with high activity and
excellent selectivity.28-31 Recently, we reported the porphyrin-
based catalyst [(TPP)Cr(THF)2][Co(CO)4] (TPP ) tetraphe-
nylporphyrinato), a highly active and selective epoxide carbo-
nylation catalyst that was also effective for the carbonylation
of cycloaliphatic epoxides.30
Using [LnM][Co(CO)4] Catalysts
catalytic reactions of epoxides that preserve chirality are highly
valued in these continued synthetic efforts. In previous reports,
we have shown that [Lewis acid][Co(CO)4] complexes catalyze
the carbonylation of epoxides and aziridines to form â-lactones
and â-lactams in a stereospecific fashion (Scheme 1).28-31
Herein, we present a new chromium(III) porphyrin-derived
carbonylation catalyst that displays activities significantly higher
than those reported in all previous studies, while maintaining
the high yields and purity that have characterized this class of
[Lewis acid][Co(CO)4] catalysts. In addition, a comprehensive
study exploring the range of epoxides amenable to this carbo-
nylation reaction is reported. As such, epoxides with ether, ester,
and amide functionality can now be carbonylated rapidly and
selectively, as detailed below.
The hydrolytic kinetic resolution of epoxides, as developed
by Jacobsen and co-workers, has provided a facile route to
enantiomerically pure epoxides with side chains containing
halogen, ether, ester, ketone, carbamate, aryl, vinyl, and alkynyl
groups.32-35 The availability of chiral-functionalized epoxides
(and their corresponding diols) has led to shorter and more
efficient syntheses of various natural products.36-40 Subsequent
(21) Direct copolymerization of CO and epoxides to give polyesters has been
met with some success: (a) Furukawa, J.; Iseda, Y.; Saegusa, T.; Fujii, H.
Makromol. Chem. 1965, 89, 263-268. (b) Jia, L.; Ding, E.; Anderson, W.
R. Chem. Commun. 2001, 1436-1437. (c) Takeuchi, D.; Sakaguchi, Y.;
Okasada, K. J. Polym. Sci., Part A: Polym. Chem. 2002, 40, 4530-4537.
(d) Allmendinger, M.; Eberhardt, R.; Luinstra, G.; Rieger, B. J. Am. Chem.
Soc. 2002, 124, 5646-5647. (e) Allmendinger, M.; Eberhardt, R.; Luinstra,
G.; Rieger, B. Macromol. Chem. Phys. 2003, 204, 564-569. (f) Lee, J. T.;
Alper, H. Macromolecules 2004, 37, 2417-2421. For a recent interesting
advance in CO/aziridine copolymerization, see: (g) Jia, L.; Sun, H.; Shay,
J. T.; Allgeier, A. M.; Hanton, S. D. J. Am. Chem. Soc. 2002, 124, 7282-
7283 and references therein.
Results and Discussion
Catalyst Synthesis. The porphyrin-based catalyst [(OEP)-
Cr(THF)2][Co(CO)4] (1; OEP ) octaethylporphyrinato; THF
) tetrahydrofuran; Figure 1) was generated by the metathesis
of NaCo(CO)4 with (OEP)CrCl. The byproduct NaCl was
removed by filtration, and 1 was isolated as a red crystalline
solid. This paramagnetic complex has a magnetic susceptibility
of 3.70 µB, indicating that three unpaired electrons are present
at the chromium center.41 IR spectroscopy reveals a strong band
at 1885 cm-1 for the [Co(CO)4-] anion, as observed in various
related compounds.30,42,43 Additionally, the crystalline [(OEP)-
Cr(THF)2][Co(CO)4] is quite robust, showing no decomposition
at temperatures as high as 250 °C.
Solid-State Structure of 1. X-ray quality crystals of 1 were
obtained by slow diffusion of pentane into a saturated THF
solution.44 The solid-state structure of 1 reveals a well-separated
ion pair (Figure 2).45 In the cationic unit, a tetradentate
porphyrinato ligand and two molecules of axially coordinated
THF provide for pseudo-octahedral coordination to the chro-
(22) Drent, E.; Kragtwijk, E. (Shell Internationale Research Maatschappij B,
V., Neth.) Eur. Pat. Appl. EP 577206; Chem. Abstr. 1994, 120, 191517c.
(23) Hinterding, K.; Jacobsen, E. N. J. Org. Chem. 1999, 64, 2164-2165.
(24) Lee, J. T.; Thomas, P. J.; Alper, H. J. Org. Chem. 2001, 66, 5424-5426.
(25) Allmendinger, M.; Eberhardt, R.; Luinstra, G. A.; Molnar, F.; Rieger, B.
Z. Anorg. Allg. Chem. 2003, 629, 1347-1352.
(26) Molnar, F.; Luinstra, G. A.; Allmendinger, M.; Rieger, B. Chem.sEur. J.
2003, 9, 1273-1280.
(27) Allmendinger, M.; Zintl, M.; Eberhardt, R.; Luinstra, G. A.; Molnar, F.;
Rieger, B. J. Organomet. Chem. 2004, 689, 971-979.
(28) Mahadevan, V.; Getzler, Y. D. Y. L.; Coates, G. W. Angew. Chem., Int.
Ed. 2002, 41, 2781-2784.
(29) Getzler, Y. D. Y. L.; Mahadevan, V.; Lobkovsky, E. B.; Coates, G. W. J.
Am. Chem. Soc. 2002, 124, 1174-1175.
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Org. Lett. 2004, 6, 373-376.
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Pure Appl. Chem. 2004, 76, 557-564.
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B.; Gould, A. E.; Furrow, M. E.; Jacobsen, E. N. J. Am. Chem. Soc. 2002,
124, 1307-1315.
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(41) Spin-only magnetic moment: µeff ) {N(N + 2)}1/2 with N ) 3, µeff
)
3.87.
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Am. Chem. Soc. 2004, 126, 1360-1362.
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2563-2567.
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G.; Bergman, R. G. J. Am. Chem. Soc. 1984, 106, 7451-7461.
(44) X-ray data: formula ) C48H60CoCrN4O6; formula weight ) 899.94;
triclinic; P1h; a ) 9.828 Å; b ) 18.793 Å; c ) 25.558 Å; R ) 75.083°; â
) 86.603°; γ ) 80.683°; V ) 4501 Å3; T ) -100 °C.; Z ) 4; R ) 0.064;
Rw ) 0.137; GOF ) 0.948.
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(38) Colby, E. A.; O’Brien, K. C.; Jamison, T. F. J. Am. Chem. Soc. 2004, 126,
998-999.
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A R T I C L E S
Schmidt et al.
psi), 60 °C, and 6 h. Since optimized reactions reached
completion at the end of the 6 h run, qualitative rate data could
be obtained from the optimized substrate/catalyst loadings,
assuming the absence of trace impurities that might impede
reactions at low catalyst loadings. Once optimized, the scope
of 1 was investigated by applying it to the carbonylation of
numerous epoxides with subsidiary functionality tethered to the
oxirane ring. The observed functional group tolerance of 1
further demonstrates the potential utility of this catalyst in
organic, polymer, and natural product synthesis.
Figure 1. Cr(III) porphyrin-based epoxide carbonylation catalysts.
Optimized substrate/catalyst loadings for the carbonylation
of simple hydrocarbon-based epoxides with 1 are listed in Table
1. The observed catalytic activities of 1 for the carbonylation
of 1,2-epoxyalkanes (C4-C12) greatly surpass all previously
reported catalysts, with turnover frequencies (TOFs) as high as
1670 h-1 (Table 1, entries 1-4). Interestingly, reactivity rates
parallel chain length for these epoxides, with longer side chains
resulting in faster carbonylation. Since the electronic properties
vary only slightly in these substrates, we attribute this trend to
solvent polarity effects, as these reactions are carried out in neat
substrate. Sterically bulky epoxides can also be carbonylated
effectively by 1, as evidenced by the rapid carbonylation of
tert-butyloxirane (11, entry 5). The use of unsaturated epoxides,
such as 1,2-epoxy-5-hexene (13), impacts the carbonylation
reaction minimally (entry 6). A comparison of saturated and
unsaturated epoxides derived from the same carbon framework
(entries 2 and 6) reveals only a slight reduction in reaction rate
for the alkene. Importantly, the pendant alkene does not appear
to insert into the postulated Co alkyl or acyl species (Scheme
1). Finally, internal epoxides can be carbonylated, as demon-
strated with trans-2,3-epoxybutane (15, entry 7). To prevent
product oligomerization, it was necessary to dilute this epoxide
slightly (25 wt % added toluene). The formation of the cis-
lactone (16) from trans-2,3-epoxybutane (15) with catalyst 1 is
consistent with our previous studies of [Lewis acid][Co(CO)4]
catalysts, suggesting a similar mechanism (Scheme 1).28-31
Applying standard reaction conditions to cis-2,3-epoxybutane
resulted in rapid oligomerization, limiting lactone formation.
Overall, a 6- to 22-fold increase in reactivity rate was observed
when comparing 1 with the previously reported 2.30
Figure 2. ORTEP view of 1 drawn with 50% thermal ellipsoids.
mium center. The anionic unit is comprised of tetrahedral
[Co(CO)4]-. The bond lengths and angles at the chromium
center are similar to those observed in other chromium porphyrin
complexes.46-51 The [Co(CO)4]- anion is structurally the same
as that found in related structures52-55 and shows no covalent
interactions with the chromium center (Co-Cr distance ) 6.52
Å).
Epoxide Carbonylation. Catalyst 1 was initially screened
for epoxide carbonylation activity with the substrate/catalyst
loadings that proved optimal for the related catalyst, [(TPP)-
Cr(THF)2][Co(CO)4] (2, Figure 1).30 While retaining the high
selectivity observed in our previous systems,28-30 catalyst 1
exhibited substantially increased carbonylation activity. For most
substrates, 1 was more than an order of magnitude faster than
had been observed with 2, the catalyst we previously reported
to be the most active and selective.30 At the current time, the
origin of this difference is not clear, but we suspect the higher
solubility and more electron-releasing ligand of 1 are respon-
sible, in part, for the increased activity. Following the initial
screening, substrate/catalyst loadings were optimized for catalyst
1, generating >99% yield of lactone for a range of epoxides.
All activities were determined by employing the standard
conditions developed in our laboratory: neat substrate, CO (900
A wide selection of glycidyl ethers can be successfully
carbonylated, yielding substituted hydroxymethyl lactone de-
rivatives, as shown in Table 2. The carbonylation of alkyl
glycidyl ethers exhibited faster reactivity with increased alkyl
chain length, as was observed with the 1,2-epoxyalkanes (Table
2, entries 1 and 2). A glycidyl silyl ether was also carbonylated
with high activity (Table 2, entry 3), while ethers containing
unsaturated groups (benzyl, furfuryl, and allyl) reacted with
moderate activities (entries 4-6). In the case of allyl glycidyl
ether (27), the product lactone (28), a viscous oil, necessitated
the addition of solvent (25 wt % toluene) to reach high
conversion. The yield of 28 was limited to ∼55% when carried
out with neat epoxide. Comparing the activities of catalysts 1
and 2 for the carbonylation of glycidyl ethers showed an increase
in reactivity rate of 12-fold (entry 2) and 4-fold (entry 3),
respectively.30 The overall tolerance of catalyst 1 to a wide array
of glycidyl ethers allows for the synthesis of protected and
functionalized hydroxymethyl-â-propiolactone derivatives.
(46) Inamo, M.; Hoshino, M.; Nakajima, K.; Aizawa, S. I.; Funahashi, S. Bull.
Chem. Soc. Jpn. 1995, 68, 2293-2303.
(47) Inamo, M.; Nakaba, H.; Nakajima, K.; Hoshino, M. Inorg. Chem. 2000,
39, 4417-4423.
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(49) Nichols, P. J.; Fallon, G. D.; Moubaraki, B.; Murray, K. S.; West, B. O.
Polyhedron 1993, 12, 2205-2213.
(50) Oyaizu, K.; Haryono, A.; Nishimura, Y.; Yamamoto, K.; Tsuchida, E. Bull.
Chem. Soc. Jpn. 1999, 72, 1781-1784.
(51) Balch, A. L.; Latosgrazynski, L.; Noll, B. C.; Olmstead, M. M.; Zovinka,
E. P. Inorg. Chem. 1992, 31, 1148-1151.
(52) Klufers, P. Z. Kristallogr. 1983, 165, 217-226.
(53) Klufers, P. Z. Kristallogr. 1984, 167, 253-260.
(54) Klufers, P. Z. Kristallogr. 1984, 167, 275-286.
(55) Klufers, P. Z. Kristallogr. 1984, 166, 143-151.
The catalytic carbonylation of cycloaliphatic epoxides was
first achieved for 8- and 12-membered hydrocarbon rings in
9
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Chromium(III) Octaethylporphyrinato Tetracarbonylcobaltate
A R T I C L E S
Table 1. Carbonylation of Aliphatic Epoxides Using [(OEP)Cr(THF)2][Co(CO)4] (1)a
1
a Conditions: neat epoxide, 60 °C, 6 h, 900 psi CO. b Determined by H NMR spectroscopy. c With 25 wt % toluene added.
our previous report employing catalyst 2.30 The optimized
substrate/catalyst ratios for carbonylation of these epoxides using
catalyst 1 are presented in Table 3. Though previously unin-
vestigated with 2, cyclopentene oxide (29) was found to
carbonylate slowly (100 equiv in 24 h) to form the cis-lactone
product (30, Table 3, entry 1).56 This was unexpected, as the
generally accepted mechanism for carbonylation with [Lewis
acid][Co(CO)4] systems predicts the formation of the trans-
lactone product due to an SN2 attack of the activated epoxide
by [Co(CO)4]- (Scheme 1). We calculated a difference of about
45 kcal/mol between the isomeric cis- and trans-lactone products
(AM1 level: -18.7 kcal/mol (trans) vs -63.2 kcal/mol (cis)).57
The high relative energy of the trans isomer helps to explain
why only the cis-lactone product was generated under our
reaction conditions. We propose that the carbonylation of
cyclopentene oxide proceeds via a cationic mechanism (Scheme
2), allowing access to the cis-lactone product that cannot be
produced with an SN2 mechanism. In this modified mechanism,
coordination of the Lewis acid to the epoxide results in the
formation of a ring-opened, secondary carbocation. Trapping
of the cation by [Co(CO)4]- yields a cobalt alkyl complex with
cis stereochemistry that can insert CO and ring-close to form
cis-lactone (30). We have tentatively discounted the presence
of â-H isomerization mechanisms due to the absence of
cyclopentenol or cyclopentanone byproducts.
Larger cycloaliphatic epoxides were carbonylated in the usual
manner, with cis-epoxides forming trans-lactones and vice versa.
The reaction rates for cyclooctene derivatives with catalyst 1
were comparable to those obtained with catalyst 2 (Table 3,
entries 2 and 3).30 Both cyclooctene oxide (31) and 1,5-
cyclooctadiene monoepoxide (33) were carbonylated to form
exclusively trans-lactones. The larger cyclododecane rings,
however, showed a modest rate enhancement when using
catalyst 1 (entries 4 and 5). In the case of cyclododecene oxide
(66% cis, 35), carbonylation of the cis-epoxide is favored,
allowing for the formation of almost exclusively trans-lactone
(36, Table 3, entry 4). Additionally, trans-1,2-epoxy-trans-5-
trans-9-cyclododecadiene (37) was carbonylated to the cis-
lactone (38), albeit slowly (Table 3, entry 5).
The superior activities observed with 1 led us to investigate
its substrate functionality tolerance, with a focus on the
carbonylation of epoxides containing stronger Lewis basic side
chains, such as esters, amides, and carbonates. To our surprise,
carbonylation of glycidyl esters (39, 41, and 43) under standard
reaction conditions (60 °C, 6 h) yielded a mixture of isomeric
â- and γ-lactones. We postulated that the â-isomer was formed
initially, as depicted in Scheme 1, followed by a slow isomer-
ization to the γ-lactone. Reduction of the substrate/catalyst ratio
for the carbonylation of these esters produced more γ-lactone,
supporting this assertion. Lowering the reaction temperature to
40 °C resulted in the exclusive formation of the desired
â-lactones. Optimized reaction conditions for the carbonylation
of glycidyl acetate (39), butyrate (41), and benzoate (43) to form
(56) Vaughan, W. R.; Cartwright, W. F.; Henzi, B. J. Am. Chem. Soc. 1972,
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A R T I C L E S
Schmidt et al.
Table 2. Carbonylation of Glycidyl Ethers Using [(OEP)Cr(THF)2][Co(CO)4] (1)a
1
a Conditions: neat epoxide, 60 °C, 6 h, 900 psi CO. b Determined by H NMR spectroscopy. c With 25 wt % toluene added.
the corresponding â-lactones are given in Table 4 (entries 1-3).
These products were readily isolated by column chromatography
(silica gel, CHCl3) without degradation. Using (R)-glycidyl
butyrate ((R)-41), the corresponding chiral â-lactone ((R)-â-
(butyroxymethyl)-â-propiolactone; (R)-42) was also prepared.
In a control experiment, â-(butyroxymethyl)-â-propiolactone
(42) was found to isomerize readily to the γ-lactone (46) using
MgBr2 as a Lewis acid catalyst. The corresponding γ-lactones
were obtained in high yields by extending reaction times to 24
h at the normal reaction temperature of 60 °C (Table 4, entries
4-6). This demonstrates that, for glycidyl esters, epoxide
carbonylation and Lewis acid-catalyzed ring expansion can be
coupled in one-pot syntheses of â-hydroxy-γ-butyrolactone
esters without the formation of undesirable side products. This
constitutes an effective new route to the formation of γ-buty-
rolactone derivatives, potentially useful in the synthesis of
pharmaceuticals and natural products based on this frame-
work.58-60
for the formation of γ-lactones from the ester-functionalized
â-lactones using 1 is shown in Scheme 3. In the first step,
coordination of the lactone carbonyl to the Lewis acid activates
the â-carbon, increasing its susceptibility to attack by the
carbonyl oxygen of the ester side chain (Scheme 3, A). This
forms a resonance-stabilized carbocation within a 1,3-dioxolane
framework (Scheme 3, B).66,67 Reopening of the dioxolane ring
to restore the ester side chain proceeds through carboxylate
attack at the methylene to give the observed ring-expanded
product. The net result of these two steps is a ring-expansive
isomerization with inversion of stereochemistry at the stereo-
genic carbon of the reactant â-lactone. To provide experimental
evidence for this mechanism, (R)-glycidyl butyrate ((R)-41) was
carbonylated to form the γ-lactone. As noted above, carbony-
lation initially proceeds to form the â-lactone with retention of
configuration at the chiral center, yielding (R)-â-butyroxy-
methyl-â-propiolactone ((R)-42). Subsequent isomerization of
(R)-42 yielded (S)-â-butyroxy-γ-butyrolactone ((S)-46), con-
sistent with the mechanism detailed in Scheme 3. This product
was confirmed by comparison of its optical rotation with a
The ring expansion of â-lactones to yield γ-lactones has been
observed previously with magnesium halides as Lewis acid
catalysts.61-65 Two related mechanisms have been proposed.
The first involves a dyotropic (concerted) ring expansion,62-65
while the second invokes a transient, zwitterionic species
coupled to rapid stepwise migration.61 A reasonable mechanism
(61) Metzger, C.; Borrmann, D.; Wegler, R. Chem. Ber. 1967, 100, 1817-
1823.
(62) Mulzer, J.; Bruntrup, G. Angew. Chem., Int. Ed. Engl. 1979, 18, 793-794.
(63) Black, T. H.; Fields, J. D. Synth. Commun. 1988, 18, 125-130.
(64) Thompson, K. L.; Chang, M. N.; Chiang, Y. C. P.; Yang, S. S.; Chabala,
J. C.; Arison, B. H.; Greenspan, M. D.; Hanf, D. P.; Yudkovitz, J.
Tetrahedron Lett. 1991, 32, 3337-3340.
(65) Reetz, M. T.; Schmitz, A.; Holdgrun, X. Tetrahedron Lett. 1989, 30, 5421-
5424.
(66) Winstein, S.; Buckles, R. E. J. Am. Chem. Soc. 1942, 64, 2780-2786.
(67) Pigman, W.; Horton, D., Eds. The Carbohydrates: Chemistry and
Biochemistry; 2nd ed.; Academic Press: New York, 1972; Vol. 1A.
(58) Brown, S. P.; Bal, B. S.; Pinnick, H. W. Tetrahedron Lett. 1981, 22, 4891-
4894.
(59) Ikan, R.; Weinstein, V.; Ravid, U. Org. Prep. Proced. Int. 1981, 13, 59-
70.
(60) Koch, S. S. C.; Chamberlin, A. R. Stud. Nat. Prod. Chem. 1995, 16, 687-
725.
9
11430 J. AM. CHEM. SOC. VOL. 127, NO. 32, 2005

Chromium(III) Octaethylporphyrinato Tetracarbonylcobaltate
A R T I C L E S
Table 3. Carbonylation of Alicyclic Epoxides Using [(OEP)Cr(THF)2][Co(CO)4] (1)a
1
a Conditions: neat epoxide, 60 °C, 6 h, 900 psi CO. b Determined by H NMR spectroscopy. c Reaction time: 24 h.
Scheme 2. Proposed Mechanism for Cyclopentene Oxide
Carbonylation Using 1
caused little or no inhibition of the carbonylation reaction. The
lack of γ-lactone formation for these substrates is most likely
a result of the inaccessibility of the larger carbocationic rings
necessitated by the proposed isomerization mechanism. Ad-
ditional support for the ring-expansion mechanism illustrated
in Scheme 3 is provided by the carbonylation of propyl 4,5-
epoxypentanoate (52, Table 4, entry 9). Although this substrate
is isomeric with the two-carbon-linked epoxide (48), a substan-
tial reduction in rate was observed (see Table 4, entries 7 and
9). This can be attributed to the formation of a cyclic carbocation
that has no available isomerization pathway. Instead, the
carbocation is forced to revert to the â-lactone product (53),
amounting to a net increase in coordination to the Lewis acid
catalyst with no further reactivity.
Epoxides with pendant amides and carbonates were also
probed as substrates for carbonylation. When functionalized with
a long-chain amide (Table 4, entry 10), the epoxide reactivity
rate was substantially reduced (TOF ) 12 h-1). The amide-
tethered â-lactone, however, was still produced in quantitative
yield. Reversible coordination of the amide to [(OEP)Cr]+ is
likely the cause of the severe inhibition observed. Carbonylation
of allyl glycidyl carbonate (56) proved unsuccessful, yielding
only an allyloxymethyl-substituted cyclic carbonate (57) as a
result of a Lewis acid-mediated isomerization (Scheme 4). This
product was identified spectroscopically by comparison with
sample of known configuration, synthesized by the reaction of
(S)-â-hydroxy-γ-butyrolactone with butyryl chloride.
Epoxides with butyryl groups attached through 2- and
3-carbon linkers (48, 50) were synthesized and found to
carbonylate rapidly to the corresponding â-lactones (Table 4,
entries 7 and 8). The observed activities were on the order of
those for 1,2-epoxyalkanes, indicating that the pendant esters
9
J. AM. CHEM. SOC. VOL. 127, NO. 32, 2005 11431

A R T I C L E S
Schmidt et al.
Table 4. Carbonylation of Glycidyl Carboxylates Using [(OEP)Cr(THF)2][Co(CO)4] (1)a
1
a Conditions: neat epoxide, 900 psi CO. b Determined by H NMR spectroscopy.
previous reports68 and was produced in quantitative yield with
a moderate rate (TOF ) 60 h-1).
Effect of CO Pressure. Although epoxide carbonylation by
catalyst 1 proceeded rapidly with high selectivity, a moderate
pressure dependence was observed. Reduction of the CO
pressure to 200 psi resulted in little or no loss in catalyst activity
for most substrates, as evidenced by the carbonylation of
glycidyl tert-butyldimethylsilyl ether (21) with 98% conversion
to the corresponding lactone (22) (epoxide/catalyst ) 1800, CO
(200 psi), 60 °C, 6 h). Further reduction of the CO pressure to
100 psi resulted in a substantial drop-off in activity, although
the corresponding lactones still comprised the primary products
in these reactions. In contrast to the reactions at higher pressure,
small amounts (∼5%) of the isomeric (noncarbonylated) ketones
were observed. Product lactones were isolated cleanly via
distillation, easily removing this byproduct. Although somewhat
(68) Baba, A.; Nozaki, T.; Matsuda, H. Bull. Chem. Soc. Jpn. 1987, 60, 1552-
1554.
9
11432 J. AM. CHEM. SOC. VOL. 127, NO. 32, 2005

Chromium(III) Octaethylporphyrinato Tetracarbonylcobaltate
A R T I C L E S
from TCI America. 1,2-Epoxyheptane (7),69 tert-butyl oxirane (11),70
glycidyl acetate (39),71 glycidyl butyrate (41),71 glycidyl benzoate (43),72
N,N-dimethyl-10,11-epoxyundecylamide (54),73 allyl glycidyl carbonate
(56),74 and NaCo(CO)475 were synthesized as previously reported. Full
characterization of the remaining epoxides can be found below. All
liquid epoxides were dried over CaH2 and vacuum distilled prior to
use; solids were used as received. Carbon monoxide was purchased
from Matheson and used without further purification. NMR chemical
shifts are given relative to residual CHCl3 (1H δ 7.26) and CDCl3 (13C
δ 77.23). The 1H NMR spectra of product lactones were identified by
comparison with published spectra for â-valerolactone (4),76 â-hep-
tanolactone (6),77 â-octanolactone (8),78 â-tridecalactone (10),77 4-tert-
butyl-2-propiolactone (12),79 4-(but-3-enyl)-2-propiolactone (14),24 cis-
3,4-dimethyl-2-propiolactone (16),28 4-(butyloxymethyl)-2-propiolactone
(20),30 4-(tert-butyldimethylsiloxymethyl)-2-propiolactone (22),30 4-(ben-
zyloxymethyl)-2-propiolactone (24),80 cis-6-oxabicyclo[3.2.0]heptan-
7-one (30),56 trans-9-oxabicyclo[6.2.0]decan-10-one (32),81 trans-9-
oxabicyclo[6.2.0]dec-4-en-10-one (34),82 trans-13-oxabicyclo[10.2.0]tetra-
decan-14-one (36),30 cis,trans-13-oxabicyclo[10.2.0]tetradeca-trans-4-
trans-8-dien-14-one (38),30 and â-acetoxy-γ-butyrolactone (45).83 1H
and 13C NMR spectra for the remaining lactones are given below.
Melting points were acquired in sealed capillary tubes under nitrogen
and are uncorrected. Optical rotations were measured on a Perkin-Elmer
241 digital polarimeter with a sodium lamp and are reported with
format: [R]TD r (c, solvent), where T ) temperature in °C, D refers to
the sodium D line (589 nm), r is the measured rotation, and c is the
concentration in g/100 mL. IR spectra were measured on a Mattson
Research Series FTIR. High-resolution mass spectra were obtained from
the Mass Spectrometry Laboratory, School of Chemical Sciences,
University of Illinois, employing electron impact conditions. Magnetic
susceptibility was measured in THF-d8 using Evans’ NMR method.84
Elemental analyses were carried out by Desert Analytics in Tucson,
Arizona.
Scheme 3. Proposed Mechanism for Ring-Expansion of
Ester-Functionalized â-Lactones
Scheme 4. Isomerization of Allyl Glycidyl Carbonate with 1
slower, the general success of epoxide carbonylation at lower
pressures provides access to functionalized lactones in any
general synthetic laboratory.
Conclusions
We have demonstrated the synthesis and utility of a new
carbonylation catalyst, [(OEP)Cr(THF)2][Co(CO)4] (1). For most
substrates, carbonylation rates using this catalyst were more than
an order of magnitude faster than previously reported catalysts.
The range of epoxides amenable to this reaction pathway has
been expanded to include those containing ester and amide side
chains. Due to this broad applicability, 1 is an ideal catalyst for
the carbonylation of epoxides, with possible applications ranging
from bulk organic syntheses to pharmaceutical and fine-chemical
production. The unprecedented turnover frequencies of 1 allow
for minimal catalyst loadings, simplifying product isolation and
removal of trace metals. Overall, the high activities and broad
substrate tolerance of 1 mark it as a highly versatile epoxide
carbonylation catalyst. Future work will focus on the conclusive
determination of the mechanism operable in these systems and
the development of new catalysts for enantioselective epoxide
carbonylation.
[(OEP)Cr(THF)2][Co(CO)4] (1). Under an atmosphere of nitrogen,
a solution of NaCo(CO)4 (160 mg, 0.820 mmol) in THF (20 mL) was
added to a flask containing (OEP)CrCl (498 mg, 0.803 mmol) and THF
(20 mL). The dark-red solution was stirred for 24 h and then allowed
to stand and settle. The resulting material was filtered, and the residual
solid was washed with several portions of THF (totaling 40 mL) to
maximize product recovery. After concentrating to 20 mL in vacuo,
the solution was layered with pentane (40 mL) for crystallization by
slow diffusion. Red crystals were isolated by filtration and dried under
vacuum. The supernatant liquid was concentrated and layered with fresh
pentane to yield a second crop of product (537 mg total, 74%); mp
>250 °C; µeff ) 3.70 µB; IR (Nujol, KCl) νCO ) 1885 cm-1. Anal.
(69) Weijers, C.; Botes, A. L.; van Dyk, M. S.; de Bont, J. A. M. Tetrahedron:
Asymmetry 1998, 9, 467-473.
Experimental Section
(70) Mischitz, M.; Kroutil, W.; Wandel, U.; Faber, K. Tetrahedron:Asymmetry
1995, 6, 1261-1272.
General Considerations. Standard Schlenk line and glovebox
techniques were used in the synthesis and reactions of catalyst 1. All
organic reactions were carried out under ambient atmosphere. The
product lactones are air stable and can be handled under ambient
atmosphere. Pentane and tetrahydrofuran (THF) were purified by
passage through commercial solvent purification columns and degassed
prior to use. (OEP)CrCl was purchased from Mid-Century Chemicals
and used as received. 1,2-Epoxybutane (3), 1,2-epoxyhexane (5), 1,2-
epoxydodecane (9), 1,2-epoxy-5-hexene (13), trans-2,3-epoxybutane
(15), glycidyl methyl ether (17), glycidyl n-butyl ether (19), glycidyl
tert-butyldimethylsilyl ether (21), benzyl glycidyl ether (23), furfuryl
glycidyl ether (25), cyclopentene oxide (29), cyclooctene oxide (31),
1,5-cyclooctadiene monoepoxide (33), cyclododecene oxide (66% cis,
35), (R)-glycidyl butyrate ((R)-41), 3-buten-1-ol, 4-penten-1-ol, tri-
ethylamine, butyryl chloride, 4-pentenoyl chloride, m-chloroperoxy-
benzoic acid, and (S)-â-hydroxy-γ-butyrolactone were purchased from
Aldrich. 1,2-Epoxy-trans-5-trans-9-cyclododecadiene (96% trans, 37)
was purchased from Lancaster. Allyl glycidyl ether (27) was purchased
(71) Davies, A. G.; Hawari, J. A. A.; Muggleton, B.; Tse, M. W. J. Chem.
Soc., Perkin Trans. 2 1981, 1132-1137.
(72) Kam, S. T.; Matier, W. L.; Mai, K. X.; Barcelon-Yang, C.; Borgman, R.
J.; O’Donnell, J. P.; Stampfli, H. F.; Sum, C. Y.; Anderson, W. G.;
Gorczynski, R. J.; Lee, R. J. J. Med. Chem. 1984, 27, 1007-1016.
(73) Glushko, L. P.; Petukhova, E. I.; Klebanskii, E. O. Zh. Organich. Khim.
1997, 33, 1527-1531.
(74) Berlin, A. A.; Popova, G. L.; Makarova, T. A. Vysokomol. Soedin. 1959,
1, 962-965.
(75) Edgell, W. F.; Lyford, J. Inorg. Chem. 1970, 9, 1932-1933.
(76) Noels, A. F.; Herman, J. J.; Teyssie, P. J. Org. Chem. 1976, 41, 2527-
2531.
(77) Romo, D.; Harrison, P. H. M.; Jenkins, S. I.; Riddoch, R. W.; Park, K.;
Yang, H. W.; Zhao, C.; Wright, G. D. Bioorg. Med. Chem. 1998, 6, 1255-
1272.
(78) Peres, R.; Lenz, R. W. Macromolecules 1993, 26, 6697-6701.
(79) Sakai, N.; Ageishi, S.; Isobe, H.; Hayashi, Y.; Yamamoto, Y. J. Chem.
Soc., Perkin Trans. 1 2000, 71-77.
(80) Yang, H. W.; Zhao, C. X.; Romo, D. Tetrahedron 1997, 53, 16471-16488.
(81) Crandall, J. K.; Machlede, W. H.; Sojka, S. A. J. Org. Chem. 1973, 38,
1149-1154.
(82) Stille, J. K.; James, D. E. J. Organomet. Chem. 1976, 108, 401-408.
(83) Tiecco, M.; Testaferri, L.; Tingoli, M.; Bartoli, D. Tetrahedron 1990, 46,
7139-7150.
(84) Evans, D. F. J. Chem. Soc. 1959, 2003-2005.
9
J. AM. CHEM. SOC. VOL. 127, NO. 32, 2005 11433

A R T I C L E S
Schmidt et al.
Calcd for C48H60CoCrN4O6: C, 64.06; H, 6.72; N, 6.23. Found: C,
63.75; H, 6.69; N, 6.21.
and brine (3 × 400 mL). The organic phase was dried over MgSO4
and the solvent removed in vacuo, leaving behind the product as a
crude oil. Purification by distillation under reduced pressure (10 mmHg)
yielded the desired product as a colorless liquid (16.2 g, 46%): 1H
NMR (CDCl3, 300 MHz) δ 4.135 (t, 2H, 3J ) 6 Hz), 2.919 (dddd, 1H,
Crystallography of 1. X-ray quality crystals were grown by
diffusion of pentane into a saturated solution of 1 in THF at room
temperature. A dark-red crystal (0.40 × 0.30 × 0.20 mm) was mounted
on a glass capillary using Paratone-N hydrocarbon oil, transferred to a
Siemens SMART85 1000 diffractometer/CCD area detector, and cooled
to a temperature of -100 °C using a calibrated nitrogen-flow low-
temperature apparatus. A primitive triclinic unit cell was determined
from a least-squares refinement on data from 60 sample frames. An
arbitrary hemisphere of data was collected using 0.3° ω-scans that were
collected for a total of 30 s per frame. The data were integrated by
SAINT86 to a maximum 2θ value of 46.5°, and the final unit cell
parameters were determined by a least-squares analysis of 6781
reflections with I > 2σ(I). The data were corrected for Lorentz and
polarization effects, but no correction for crystal decay was applied.
3
3
3
2
3J ) 6 Hz, J ) 5 Hz, J ) 4 Hz, J ) 3 Hz), 2.690 (dd, 1H, J ) 5
3
2
3
Hz, J ) 4 Hz), 2.417 (dd, 1H, J ) 5 Hz, J ) 3 Hz), 2.209 (t, 2H,
3J ) 7 Hz), 1.837 (dtd, 1H, 2J ) 14 Hz, 3J ) 6 Hz, 3J ) 5 Hz), 1.720
2
3
3
(dq, 1H, J ) 14 Hz, J ) 6 Hz), 1.566 (sext, 2H, J ) 7 Hz), 0.860
(t, 3H, J ) 7 Hz); 13C NMR (CDCl3, 75 MHz) δ 173.6, 61.2, 49.7,
3
46.9, 36.2, 32.1, 18.5, 13.8; IR (neat, KCl) νCO ) 1738 cm-1; HRMS
(EI) m/z calcd (C8H14O3) 158.0943, found 158.0937.
4,5-Epoxypentyl Butyrate (50). Procedure analogous to that of 3,4-
1
epoxybutyl butyrate, substituting 4-penten-1-ol for 3-buten-1-ol: H
3
4
NMR (CDCl3, 300 MHz) δ 4.025 (td, 2H, J ) 6 Hz, J ) 1.5 Hz),
2
3
2.843 (mult, 1H), 2.662 (dd, 1H, J ) 5 Hz, J ) 4 Hz), 2.385 (dd,
1H, 2J ) 5 Hz, 3J ) 3 Hz), 2.186 (t, 2H, 3J ) 8 Hz), 1.707 (mult, 2H),
1.63-1.43 (mult, 2H), 1.553 (sext, 2H, 3J ) 8 Hz), 0.850 (t, 3H, 3J )
8 Hz); 13C NMR (CDCl3, 75 MHz) δ 173.6, 63.7, 51.7, 47.0, 36.2,
29.1, 25.2, 18.5, 13.7; IR (neat, KCl) νCO ) 1737 cm-1; HRMS (EI)
m/z calcd (C9H16O3 + H+) 173.1178, found 173.1179.
An absorption correction was performed using SADABS87 (Tmax
0.879, Tmin ) 0.778).
)
Of the 31 499 reflections that comprised the hemisphere, 12 902 were
unique (Rint ) 0.097), and the equivalent reflections were averaged.
The structure was solved by direct methods88 and expanded using
Fourier techniques,89 using SHELX 97.90 Within the two molecules of
1 that make up the asymmetric unit, two THF ligands and one ethyl
group were disordered. Excluding the disordered carbon atoms, the non-
hydrogen atoms were refined anisotropically. Hydrogen atoms were
included as fixed atoms but not refined. The final cycle of full-matrix
least squares refinement was based on 12 902 observed reflections and
1277 variable parameters and converged with final residuals:91 R )
0.064, Rw ) 0.137, and GOF ) 0.948. The analytical forms of the
scattering factor tables for the neutral atoms were used,92 and all
scattering factors were corrected for both the real and imaginary
components of anomalous dispersion.93
Propyl 4,5-Epoxypentanoate (52). Procedure analogous to that of
3,4-epoxybutyl butyrate, substituting n-propanol for 3-buten-1-ol and
4-pentenoyl chloride for butyryl chloride: 1H NMR (CDCl3, 300 MHz)
3
3
δ 3.979 (t, 2H, J ) 7 Hz), 2.921 (mult, 1H), 2.698 (dd, 1H, J ) 5
Hz, 3J ) 4 Hz), 2.442 (dd, 1H, 3J ) 5 Hz, 3J ) 2.4 Hz), 2.400 (t, 2H,
3J ) 8 Hz), 1.907 (mult, 1H), 1.712 (sext, 1H, 3J ) 7 Hz), 1.588 (sext,
2H, 3J ) 7 Hz), 0.876 (t, 3H, 3J ) 7 Hz); 13C NMR (CDCl3, 75 MHz)
δ 173.1, 66.3, 51.4, 47.2, 30.6, 27.8, 22.1, 10.5; IR (neat, KCl) νCO
)
1736 cm-1; HRMS (EI) m/z calcd (C8H14O3 + H+) 159.1021, found
159.1017.
General Procedure for the Carbonylation of Epoxides. Carb-
onylations were carried out with 150-500 mg of epoxide. Substrate:
catalyst ratios are accurate to within 5%. Under nitrogen at room
temperature, a 4-mL glass vial equipped with a stir bar was charged
with catalyst followed by epoxide. This was immediately transferred
to a custom-built, 6-well, high-pressure reactor.30 The reactor was
pressurized to 900 psi with CO and heated to 60 °C with stirring. The
temperature was held constant for 6 h, at which point the reactor was
submerged in dry ice for 15 min. After careful venting of excess CO,
the glass vial was removed and product yield determined by 1H NMR.
Pure lactones were isolated by careful vacuum distillation, unless noted
below.
3,4-Epoxybutyl Butyrate (48). A 500 mL round-bottomed flask
was charged with 3-buten-1-ol (16.2 g, 225 mmol), toluene (150 mL),
and triethylamine (35 mL). After cooling to 0 °C, butyryl chloride (25
mL, 25.5 g, 238 mmol) was added dropwise via an addition funnel.
The reaction mixture was stirred at 0 °C for 2 h and then allowed to
warm to ambient temperature overnight. After filtration, the toluene
solution was washed three times with H2O (100 mL) and twice with
brine (100 mL). After drying over MgSO4, the solvent was removed
under vacuum to yield 3-butenyl butyrate as a crude oil. This oil was
placed in a 2 L round-bottomed flask and dissolved in CH2Cl2 (700
mL). After cooling to 0 °C, m-chloroperoxybenzoic acid (77% purity
(Aldrich), 81 g, 360 mmol) was added in portions over 20 min. The
ice bath was removed after 1 h, and the reaction was left to stir
overnight. Excess peroxide was quenched by the slow addition of 10%
NaHSO3(aq) (400 mL) at 0 °C, followed by slow addition of NaHCO3-
(aq) (sat.) until bubbling ceased. The product was extracted three times
with CH2Cl2 (200 mL) and washed with NaHCO3(aq) (sat., 400 mL)
Characterization of Lactones. 4-(Methoxymethyl)-2-propiolac-
tone (18): 1H NMR (CDCl3, 300 MHz) δ 4.644 (dddd, 1H, 3J ) 6 Hz,
3J ) 5 Hz, 3J ) 5 Hz, 3J ) 3 Hz), 3.739 (dd, 1H, 2J ) 11 Hz, 3J ) 3
2
3
2
Hz), 3.635 (dd, 1H, J ) 11 Hz, J ) 5 Hz), 3.463 (dd, 1H, J ) 16
Hz, 3J ) 6 Hz), 3.431 (s, 3H), 3.379 (dd, 1H, 2J ) 16 Hz, 3J ) 5 Hz);
13C NMR (CDCl3, 75 MHz) δ 167.9, 72.1, 69.6, 59.8, 39.7; IR (neat,
KCl) νCO ) 1827 cm-1; HRMS (EI) m/z calcd (C5H8O3) 116.0473,
found 116.0476.
(85) SMART: Area-Detector Software Package; Siemens Industrial Automation,
Inc.: Madison, WI, 1995.
4-(Furfuryloxymethyl)-2-propiolactone (26): 1H NMR (CDCl3, 300
MHz) δ 7.416 (dd, 1H, 3J ) 1.5 Hz, 3J ) 1.5 Hz), 6.351 (d, 2H, 3J )
(86) SAINT: SAX Area-Detector Integration Program, version 4.024; Siemens
Industrial Automation, Inc.: Madison, WI, 1995.
3
3
3
3
(87) SADABS: Siemens Area Detector ABSorption Correction Program; George
Sheldrick, 1996.
1.5 Hz), 4.634 (dddd, 1H, J ) 6 Hz, J ) 5 Hz, J ) 5 Hz, J ) 3
Hz), 4.575 (d, 1H, 2J ) 13 Hz), 4.516 (d, 1H, 2J ) 13 Hz), 3.812 (dd,
(88) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Guagliardi, A. J. Appl.
Crystallogr. 1993, 26, 343-350.
2
3
2
3
1H, J ) 12 Hz, J ) 3 Hz), 3.711 (dd, 1H, J ) 12 Hz, J ) 5 Hz),
3.448 (dd, 1H, 2J ) 16 Hz, 3J ) 6 Hz), 3.363 (dd, 1H, 2J ) 16 Hz, 3J
) 5 Hz); 13C NMR (CDCl3, 75 MHz) δ 167.8, 151.1, 143.2, 110.5,
110.1, 69.4, 69.2, 65.5, 39.9; IR (neat, KCl) νCO ) 1826 cm-1; HRMS
(EI) m/z calcd (C9H10O4) 182.0579, found 182.0578.
(89) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.; Garcia-
Granda, S.; Gould, R. O.; Smits, J. M. M.; Smykalla, C. The DIRDIF
Program System, Technical Report of the Crystallography Laboratory;
University of Nijmegen: The Netherlands, 1992.
(90) Sheldrick, G. M. SHELX 97; Universita¨t Go¨ttingen: Go¨ttingen, Germany,
1997.
1
(91) R ) Σ ||Fo| - |Fc||/Σ |Fo|, Rw ) [(Σ w(|Fo| - |Fc|)2/Σ w Fo2)]1/2, GOF )
[Σ w(|Fo| - |Fc|)2/(No - Nv)]1/2, where No ) number of observations and
Nv ) number of variables, and the weight w ) 4 Fo2/σ2(Fo)2 ) [σ2(Fo) +
(pFo/2)2]-1 and p is the factor used to lower the weight of intense reflections.
(92) Cromer, D. T.; Waber, J. T. In International Tables for X-ray Crystal-
lography; The Kynoch Press: Birmingham, England, 1974; Vol. IV, Table
2.2A.
4-(Allyloxymethyl)-2-propiolactone (28): H NMR (CDCl3, 300
3
3
3
MHz) δ 5.885 (ddt, 1H, J ) 17 Hz, J ) 10 Hz, J ) 6 Hz), 5.286
(ddt, 1H, 3J ) 17 Hz, 2J ) 1.5 Hz, 4J ) 1.5 Hz), 5.213 (ddt, 1H, 3J )
2
4
3
3
10 Hz, J ) 1.5 Hz, J ) 1.5 Hz), 4.655 (dddd, 1H, J ) 6 Hz, J )
5 Hz, 3J ) 5 Hz, 3J ) 3 Hz), 4.068 (mult, 2H), 3.790 (dd, 1H, 2J ) 12
Hz, 3J ) 3 Hz), 3.688 (dd, 1H, 2J ) 12 Hz, 3J ) 5 Hz), 3.472 (dd, 1H,
(93) Ibers, J. A.; Hamilton, W. C. Acta Crystallogr. 1964, 17, 781-782.
9
11434 J. AM. CHEM. SOC. VOL. 127, NO. 32, 2005

Chromium(III) Octaethylporphyrinato Tetracarbonylcobaltate
A R T I C L E S
3
2
3
2J ) 16 Hz, J ) 6 Hz), 3.398 (dd, 1H, J ) 16 Hz, J ) 5 Hz); 13C
NMR (CDCl3, 75 MHz) δ 167.9, 134.1, 117.7, 72.7, 69.5, 69.3, 39.7;
IR (neat, KCl) νCO ) 1827 cm-1; HRMS (EI) m/z calcd (C7H10O3 +
H+) 143.0708, found 143.0706.
4-(2-Butyroxyethyl)-2-propiolactone (49): 1H NMR (CDCl3, 300
MHz) δ 4.584 (dtd, 1H, J ) 8 Hz, J ) 6 Hz, J ) 4.5 Hz), 4.24-
3
3
3
2
3
4.08 (mult, 2H), 3.540 (dd, 1H, J ) 17 Hz, J ) 6 Hz), 3.124 (dd,
2
3
3
1H, J ) 17 Hz, J ) 4.5 Hz), 2.235 (t, 2H, J ) 7 Hz), 2.105 (mult,
2H), 1.588 (sext, 2H, 3J ) 7 Hz), 0.888 (t, 3H, 3J ) 7 Hz); 13C NMR
(CDCl3, 75 MHz) δ 173.6, 167.9, 68.7, 60.1, 43.5, 36.2, 34.0, 18.5,
13.8; IR (neat, KCl) νCO ) 1828 (lactone), 1735 (butyryl) cm-1; HRMS
(EI) m/z calcd (C9H14O4 + H+) 187.0970, found 187.0966.
4-(Acetoxymethyl)-2-propiolactone (40): Isolated by column chro-
matography (silica/CHCl3): 1H NMR (CDCl3, 300 MHz) δ 4.698 (dddd,
1H, J ) 6 Hz, J ) 5 Hz, J ) 4 Hz, J ) 3 Hz), 4.449 (dd, 1H, J
) 13 Hz, J ) 3 Hz), 4.203 (dd, 1H, J ) 13 Hz, J ) 5 Hz), 3.525
(dd, 1H, J ) 16 Hz, J ) 6 Hz), 3.296 (dd, 1H, J ) 16 Hz, J ) 4
Hz), 2.066 (s, 3H); 13C NMR (CDCl3, 75 MHz) δ 170.7, 167.2, 67.9,
63.6, 40.3, 20.8; IR (neat, KCl) νCO ) 1832 (lactone), 1743 (acetyl)
cm-1; HRMS (EI) m/z calcd (C6H8O4 + H+) 145.0501, found 145.0504.
4-(Butyroxymethyl)-2-propiolactone (42): Isolated by column
chromatography (silica/CHCl3): 1H NMR (CDCl3, 400 MHz) δ 4.711
3
3
3
3
2
3
2
3
2
3
2
3
4-(3-Butyroxypropyl)-2-propiolactone (51): 1H NMR (CDCl3, 300
MHz) δ 4.535 (dtd, 1H, 3J ) 8 Hz, 3J ) 6 Hz, 3J ) 4 Hz), 4.113 (td,
2H, J ) 6 Hz, J ) 2 Hz), 3.538 (dd, 1H, J ) 16 Hz, J ) 6 Hz),
3.079 (dd, 1H, J ) 16 Hz, J ) 4 Hz), 2.276 (t, 2H, J ) 7 Hz),
1.93-1.72 (mult, 4H), 1.639 (sext, 2H, 3J ) 7 Hz), 0.935 (t, 3H, 3J )
7 Hz); 13C NMR (CDCl3, 75 MHz) δ 173.8, 168.2, 70.9, 63.4, 43.2,
36.3, 31.7, 24.6, 18.6, 13.9; IR (neat, KCl) νCO ) 1828 (lactone), 1732
(butyryl) cm-1; HRMS (EI) m/z calcd (C10H16O4 + H+) 201.1127, found
201.1122.
3
4
2
3
2
3
3
3
3
3
3
(dddd, 1H, J ) 6 Hz, J ) 5 Hz, J ) 4 Hz, J ) 3 Hz), 4.497 (dd,
2
3
2
3
1H, J ) 13 Hz, J ) 3 Hz), 4.241 (dd, 1H, J ) 13 Hz, J ) 5 Hz),
3.537 (dd, 1H, 2J ) 16 Hz, 3J ) 6 Hz), 3.317 (dd, 1H, 2J ) 16 Hz, 3J
) 4 Hz), 2.335 (t, 2H, 3J ) 7 Hz), 1.644 (sext, 2H, 3J ) 7 Hz), 0.931
Propyl 3-(4-oxo-oxetan-2-yl)propionate (53): 1H NMR (CDCl3,
300 MHz) δ 4.584 (dddd, 1H, 3J ) 7 Hz, 3J ) 6 Hz, 3J ) 5 Hz, 3J )
(t, 3H, J ) 7 Hz); 13C NMR (CDCl3, 75 MHz) δ 173.3, 166.9, 67.9,
3
3
2
3
63.3, 40.4, 36.0, 18.5, 13.8; IR (neat, KCl) νCO ) 1831 (lactone), 1738
(butyryl) cm-1; HRMS (EI) m/z calcd (C8H12O4 + H+) 173.0814, found
173.0809.
(R)-4-(Butyroxymethyl)-2-propiolactone ((R)-42): Isolated by
column chromatography (silica/CHCl3): [R]21 -38.4° (c ) 1.14,
4 Hz), 4.045 (t, 2H, J ) 7 Hz), 3.551 (dd, 1H, J ) 16 Hz, J ) 6
Hz), 3.111 (dd, 1H, 2J ) 16 Hz, 3J ) 4 Hz), 2.497 (dd, 1H, 3J ) 7 Hz,
2J ) 4 Hz), 2.471 (dd, 1H, J ) 7 Hz, J ) 4 Hz), 2.162 (dtd, 1H, J
3
2
2
3
3
2
3
) 22 Hz, J ) 7 Hz, J ) 5 Hz), 2.075 (dq, 1H, J ) 22 Hz, J ) 7
3
D
Hz), 1.648 (sext, 2H, 3J ) 7 Hz), 0.933 (t, 3H, J ) 7 Hz); 13C NMR
CHCl3).
(CDCl3, 75 MHz) δ 172.5, 167.9, 70.3, 66.7, 43.2, 30.2, 29.8, 22.1,
10.6; IR (neat, KCl) νCO ) 1828 (lactone), 1731 (butyryl) cm-1; HRMS
(EI) m/z calcd (C9H14O4 + H+) 187.0970, found 187.0972.
4-(Benzoyloxymethyl)-2-propiolactone (44): Isolated by column
chromatography (silica/CHCl3): 1H NMR (CDCl3, 300 MHz) δ 8.035
(d, 2H, 3J ) 8 Hz), 7.589 (t, 1H, 3J ) 8 Hz), 7.451 (t, 2H, 3J ) 8 Hz),
4.866 (dddd, 1H, 3J ) 6 Hz, 3J ) 5 Hz, 3J ) 4 Hz, 3J ) 3 Hz), 4.726
N,N-Dimethyl-9-(4-oxo-oxetan-2-yl)nonamide (55): 1H NMR
3
3
3
(CDCl3, 300 MHz) δ 4.496 (dtd, 1H, J ) 7 Hz, J ) 6 Hz, J ) 4
2
3
2
3
2
3
2
(dd, 1H, J ) 13 Hz, J ) 3 Hz), 4.540 (dd, 1H, J ) 13 Hz, J ) 5
Hz), 3.502 (dd, 1H, J ) 16 Hz, J ) 6 Hz), 3.048 (dd, 1H, J ) 16
2
3
2
Hz, 3J ) 4 Hz), 2.997 (s, 3H), 2.936 (s, 3H), 2.296 (t, 2H, 3J ) 8 Hz),
Hz), 3.630 (dd, 1H, J ) 17 Hz, J ) 6 Hz), 3.439 (dd, 1H, J ) 17
Hz, J ) 4 Hz); 13C NMR (CDCl3, 75 MHz) δ 167.0, 166.2, 133.8,
3
1.9-1.7 (mult, 2H), 1.617 (pent, 2H, 3J ) 8 Hz), 1.313 (br, 10H); 13
C
130.0, 129.3, 128.8, 68.0, 64.0, 40.5; IR (neat, KCl) νCO ) 1833
(lactone), 1723 (benzoyl) cm-1; HRMS (EI) m/z calcd (C11H10O4)
206.0579, found 206.0584.
â-Butyroxy-γ-butyrolactone (46):94 1H NMR (CDCl3, 300 MHz)
NMR (CDCl3, 75 MHz) δ 173.4, 168.7, 71.5, 43.1, 37.5, 35.5, 34.8,
33.5, 29.6, 29.5, 29.4, 29.3, 25.3, 25.1; IR (neat, KCl) νCO ) 1812
(lactone), 1644 (amide) cm-1; HRMS (EI) m/z calcd (C14H25NO3)
255.1834, found 255.1839.
3
3
2
δ 5.404 (dd, 1H, J ) 7 Hz, J ) 5 Hz), 4.481 (dd, 1H, J ) 11 Hz,
Isomerization of Allyl Glycidyl Carbonate (56). Under nitrogen
at room temperature, a 4-mL glass vial equipped with a stir bar was
charged with 1 (3 mg, 4.0 µmol) followed by allyl glycidyl carbonate
(56, 157 mg, 0.99 mmol, 250 equiv). This was immediately transferred
to a custom-built, 6-well, high-pressure reactor.30 The reactor was
pressurized to 900 psi with CO and heated to 60 °C with stirring. The
temperature was held constant for 6 h, at which point the reactor was
submerged in dry ice for 15 min. After careful venting of excess CO,
the glass vial was removed. 1H NMR confirmed quantitative conversion
to 4-allyloxymethyl-1,3-dioxolan-2-one (57) by comparison with previ-
ously reported spectroscopy.68
3J ) 5 Hz), 4.313 (d, 1H, 2J ) 11 Hz), 2.837 (dd, 1H, 2J ) 18 Hz, 3J
2
3
) 7 Hz), 2.553 (d, 1H, J ) 18 Hz), 2.282 (t, 2H, J ) 7 Hz), 1.616
(sext, 2H, 3J ) 7 Hz), 0.913 (t, 3H, 3J ) 7 Hz); 13C NMR (CDCl3, 75
MHz) δ 174.9, 173.2, 73.4, 69.8, 36.0, 34.8, 18.4, 13.8; IR (neat, KCl)
νCO ) 1789 (lactone), 1738 (butyryl) cm-1; HRMS (EI) m/z calcd
(C8H12O4 + H+) 173.0814, found 173.0812.
(S)-â-Butyroxy-γ-butyrolactone ((S)-46): Method a. Synthesized
as previously reported, by reaction of butyryl chloride with (S)-â-
hydroxy-γ-butyrolactone;94 [R]21D -77.8° (c ) 1.02, CHCl3). Method
b. Carbonylation of (R)-glycidyl butyrate ((R)-41) using catalyst 1;
[R]21 -78.8° (c ) 0.99, CHCl3).
D
Acknowledgment. G.W.C. gratefully acknowledges a Pack-
ard Foundation Fellowship in Science and Engineering and an
Arnold and Mabel Beckman Foundation Young Investigator
Award, as well as funding from the NSF (CHE-0243605) and
Metabolix, Inc.
â-Benzoyloxy-γ-butyrolactone (47): Isolated by recrystallization
from ethanol at -30 °C: 1H NMR (CDCl3, 300 MHz) δ 8.021 (d, 2H,
3
3
3
3J ) 7 Hz), 7.603 (t, 1H, J ) 7 Hz), 7.458 (dd, 2H, J ) 7 Hz, J )
7 Hz), 5.686 (ddt, 1H, 3J ) 7 Hz, 3J ) 5 Hz, 3J ) 1.5 Hz), 4.622 (dd,
1H, 2J ) 11 Hz, 3J ) 5 Hz), 4.521 (dd, 1H, 2J ) 11 Hz, 3J ) 1.5 Hz),
2.978 (dd, 1H, 2J ) 18 Hz, 3J ) 7 Hz), 2.776 (dd, 1H, 2J ) 18 Hz, 3J
) 1.5 Hz); 13C NMR (CDCl3, 75 MHz) δ 174.8, 166.1, 134.0, 130.0,
129.1, 128.8, 73.4, 70.5, 34.9; IR (Nujol, KCl) νCO ) 1771 (lactone),
1716 (benzoyl) cm-1; HRMS (EI) m/z calcd (C11H10O4) 206.0579, found
206.0576.
Supporting Information Available: Table of product distri-
butions for various substrate/catalyst ratios in the carbonylation
of cyclododecene oxide and crystallographic data for 1. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(94) The synthesis, IR spectrum, boiling point, and refractive index of 46 have
previously been reported: van Tamelen, E. E.; Strong, F. M.; Quarck, U.
C. J. Am. Chem. Soc. 1959, 81, 750-751.
JA051874U
9
J. AM. CHEM. SOC. VOL. 127, NO. 32, 2005 11435