Different reactivity patterns of trimethylsilyl- and phenyl-substituted propargylallenes: Fe2(CO)9- and [Ag]+-promoted cyclizations

Article abstract of DOI:10.1021/om9009872

Thermolytic rearrangement of the diphenyl-propargylallene [3,3-(biphenyl-2,2′-diyl)-1-phenyl-1{9-[(phenylethynyl]-9H-fluorenyl} allene], 9, yields the bis-fluorenyliden-bis-allene 10, which undergoes electrocyclization to form 3,4-di(fluorenyliden)-1,2-diphenylcyclobutene, 12, in which the overlapping fluorenylidenes give rise to C₂ symmetry. The propargylallene 9 reacts with iron carbonyls to form 15, in which an (η⁵-fiuorenyl)Fe(CO)₂ moiety is linked both directly and via a bridging =C(Ph)-C(=O)linkage to a cyclobutene ring possessing a phenyl group and a spiro-bonded fluorenyl substituent. The diphenyl-propargylallene 9 and its bis(trimethylsilyl)propargylallene analogue, 2, each react with Co ₂(CO)₈ to furnish the corresponding alkyne-Co ₂(CO)₆ complexes 14 and 13, respectively. Treatment of the diphenyl-propargylallene 9 or the mono(trimethylsilyl)propargylallene 25 with silver nitrate in methanol or water effects cyclization of the aliene onto the alkyne to furnish a cyclopentadiene that bears a 9-methoxy- or 9-hydroxy-fluorenyl substituent and is also spiro-bonded to a second fluorenyl moiety. The reaction of 3,3-(biphenyl-2,2′-diyl)-l-bromo-l-phenylallene with Fe₂(CO)₉ yields the novel bicyclo[3.2.0]heptadienone 21, which possesses two phenyl groups and is also spiro-linked to two fluorenyl fragments. All new compounds were characterized by NMR spectroscopy and X-ray crystallography.

Full text of DOI:10.1021/om9009872

676 Organometallics 2010, 29, 676–686
DOI: 10.1021/om9009872
Different Reactivity Patterns of Trimethylsilyl- and Phenyl-Substituted
Propargylallenes: Fe2(CO)9- and [Ag]þ-Promoted Cyclizations
ꢀ
Pascal Oulie, Lena Altes, Sandra Milosevic, Romain Bouteille, Helge Muller-Bunz, and
€
Michael J. McGlinchey*
School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
Received November 12, 2009
Thermolytic rearrangement of the diphenyl-propargylallene [3,3-(biphenyl-2,20-diyl)-1-phenyl-1-
{9-[(phenylethynyl]-9H-fluorenyl}allene], 9, yields the bis-fluorenyliden-bis-allene 10, which undergoes
electrocyclization to form 3,4-di(fluorenyliden)-1,2-diphenylcyclobutene, 12, in which the overlapping
fluorenylidenes give rise to C2 symmetry. The propargylallene 9 reacts with iron carbonyls to form 15, in
which an (η5-fluorenyl)Fe(CO)2 moiety is linked both directly and via a bridging dC(Ph)-C(dO)-
linkage to a cyclobutene ring possessing a phenyl group and a spiro-bonded fluorenyl substituent.
The diphenyl-propargylallene 9 and its bis(trimethylsilyl)propargylallene analogue, 2, each react with
Co2(CO)8 to furnish the corresponding alkyne-Co2(CO)6 complexes 14 and 13, respectively. Treatment
of the diphenyl-propargylallene 9 or the mono(trimethylsilyl)propargylallene 25 with silver nitrate in
methanol or water effects cyclization of the allene onto the alkyne to furnish a cyclopentadiene that bears
a 9-methoxy- or 9-hydroxy-fluorenyl substituent and is also spiro-bonded to a second fluorenyl moiety.
The reaction of 3,3-(biphenyl-2,20-diyl)-1-bromo-1-phenylallene with Fe2(CO)9 yields the novel bicyclo-
[3.2.0]heptadienone 21, which possesses two phenyl groups and is also spiro-linked to two fluorenyl
fragments. All new compounds were characterized by NMR spectroscopy and X-ray crystallography.
Introduction
reactivity of propargylallenes bearing trimethylsilyl or phenyl
substituents. Our initial investigations5 on the conversion
of fluorenylidene-allenes, via a series of isomeric 1,2-dialky-
lidenecyclobutanes, to electroluminescent tetracenes promp-
ted us to pursue the chemistry of other allenes, including
those bearing ferrocenyl,6 phosphino,7 or silyl8 substituents,
each of which led to unexpected results.
Thus, treatment of the trimethylsilyl-bromoallene, 1, with
half an equivalent of butyllithium furnished the propargyl-
allene 2, the product of head-to-tail coupling, which,
when thermolyzed, yielded the disilyl-diallene 3. However,
attempted electrocyclization to the 3,4-bis(fluorenyliden)-
cyclobutene 4 led instead to the novel dihydrotetrabenzo-
quatercyclopentadiene 5.9 Moreover, removal of the bulky
trimethylsilyl groups in 3 also did not result in cyclization;
instead the molecule underwent isomerization to form the
hexa-1,5-dien-3-yne 6, which had previously been prepared
via a different multistep route.10
The number of conceivable isomers of C6H6 is 218! Of
course, the chemistry of benzene-and even of its Dewar,
prismane, and benzvalene isomers-has been comprehen-
sively investigated.1 However, the majority of this enormous
number of potential molecules will never be capable of
existence under normal conditions because of the intrinsic
strain imposed by the presence of triple bonds or allene units
in small rings or of bridgehead double bonds that would
violate Bredt’s rule.
There are only 15 acyclic isomers of C6H6; these include
diynes, dienynes, and tetraenes, and their existence owes
much to the pioneering investigations of Hopf and his
colleagues.2 Most importantly, we note his synthesis of
hexa-1,2-dien-5-yne (C6H6), the parent propargylallene.3
Nevertheless, the chemistry of propargylallenes, in parti-
cular their organometallic chemistry, remains underexploited.
We here focus on the syntheses, structures, and reactivity of
several propargylallenes, their organic and organometallic
derivatives, and their rearrangement behavior.
(5) (a) Harrington, L. E.; Britten, J. F.; McGlinchey, M. J. Org. Lett.
2004, 6, 787–790. (b) Banide, E. V.; Ortin, Y.; Seward, C. M.; Harrington,
L. E.; M€uller-Bunz, H.; McGlinchey, M. J. Chem.-Eur. J. 2006, 12, 3275–
3286.
In continuation of our studies on the organic and organo-
metallic chemistry of fluorenylidene-containing allenes and
their dimers,4 we here describe the syntheses, structures, and
(6) Banide, E. V.; Ortin, Y.; Chamiot, B.; Cassidy, A.; Niehaus, J.;
€
Moore, A.; Seward, C. M.; Muller-Bunz, H.; McGlinchey, M. J.
Organometallics 2008, 27, 4173–4182.
(7) Banide, E. V.; Grealis, J. P.; Muller-Bunz, H.; Ortin, Y.; Casey,
€
M.; Mendicute-Fierro, C.; Lagunas, M. C.; McGlinchey, M. J.
*Corresponding author. Phone: þ353-1-716-2880. Fax: þ353-1-716-1178.
E-mail: michael.mcglinchey@ucd.ie.
(1) Hopf, H. Classics in Hydrocarbon Chemistry; Wiley-VCH:
Weinheim, 2000.
(2) Maurer, H.; Hopf, H. Eur. J. Org. Chem. 2005, 2702–2707.
(3) Hopf, H. Chem. Ber. 1971, 104, 3087–3095.
ꢀ
(4) Banide, E. V.; Oulie, P.; McGlinchey, M. J. Pure Appl. Chem.
J. Organomet. Chem. 2008, 693, 1759–1770.
(8) Banide, E. V.; Molloy, B. C.; Ortin, Y.; Muller-Bunz, H.;
€
McGlinchey, M. J. Eur. J. Org. Chem. 2007, 2611–2622.
ꢀ
€
(9) Banide, E. V.; Oulie, P.; Muller-Bunz, H.; McGlinchey, M. J.
Organometallics 2008, 27, 5657–5664.
2009, 81, 1–17.
(10) Fischer, H.; Fischer, H. Tetrahedron 1965, 25, 955–958.
r
pubs.acs.org/Organometallics
Published on Web 01/07/2010
2010 American Chemical Society

Article
Treatment of either the bis(trimethylsilyl)propargylallene 2
Organometallics, Vol. 29, No. 3, 2010 677
or the disilyl-diallene 3with di-iron nonacarbonyl led initially to
the cyclized product 7, whereby the (η5-fluorenyl)Fe(CO)2
moiety is linked both directly and via a bridging carbonyl to
a cyclopentadiene ring bearing two trimethylsilyl substituents
and a spiro-bonded fluorenyl fragment. This observation
suggests the existence of an equilibrium between the propargyl-
allene, 2, and the bis-allene, 3. Furthermore, when the complex
7 was allowed to stand in chloroform at room temperature, it
gradually decomposed with loss of metal to yield the lactone 8,
a previously unknown bicyclo[3.3.0]oxa-octadienone system.9
Results and Discussion
Figure 1. Molecular structure of the diphenyl propargylallene
9. Thermal ellipsoids are at 30%.
Syntheses and Reactivity of Propargylallenes. In light of the
results gained with the bis(trimethylsilyl)propargylallene 2
and the bis(trimethylsilyl)diallene 3, it was decided to pre-
pare and study the reactivity of the corresponding diphenyl
systems 9 and 10, respectively. Incorporation of a planar aryl
group in place of a bulky three-dimensional trimethylsilyl
substituent would be expected to reduce the steric hindrance
in 9 relative to 2. However, the available literature on these
molecules is rather confusing, and we describe here our
attempt to clarify the situation. In 1965, Kuhn and Rewicki
reported that when 9-phenylethynylfluoren-9-ol was treated
with TiCl3-EtOH and trisodium citrate at 70-80 °C, a
colorless, light-sensitive hydrocarbon, C42H26, “presumably
3,4-diphenyl-1,6-bis(biphenylene)-1,2,4,5-hexatetraene”, 10,
mp 268-270 °C, turning brown-red from 180 °C, was
isolated in 20% yield. Interestingly, this product absorbed
only 3 molar equiv of H2.11 Subsequently, in 1975, Toda and
Takehira claimed that the CuCl-mediated coupling of the
phenyl-bromoallene 11 in DMF at room temperature furni-
shed 10, mp 173.5-174 °C.12 Since melting points are some-
times the only viable historical link to assignments made
prior to the ready availability of modern spectroscopic or
X-ray diffraction techniques,13 we wished to correlate our
observations with the original data.
Figure 2. Structure of the difluorenylidene-cyclobutene 12.
Thermal ellipsoids are at 50%.
In our hands, treatment of the phenylbromoallene 11 with
half an equivalent of butyllithium delivered the diphenyl-
propargylallene 9 as pale yellow crystals, mp 284-286 °C, in
43% yield. When 9 was heated at reflux in toluene for 5 h, an
orange product, mp 266-268 °C, was unambiguously identi-
fied as 3,4-di(9-fluorenyliden)-1,2-diphenylcyclobutene, 12.
One might surmise that the product reported by Toda was in
fact the diallene 10 (mp 174 °C), as was the molecule
described by Kuhn as turning brown-red from 180 °C; how-
ever, the melting point of Kuhn’s ultimate product indicates
that electrocyclization must have occurred to form the
cyclobutene 12. The X-ray crystal structures of the diphe-
nylpropargylallene 9 and the cyclobutene 12 are shown in
Figures 1 and 2, respectively. In 9, the carbon-carbon
distances in the allenyl and alkynyl units are within the
normal ranges (C(9)-C(10) 1.315(2) A, C(10)-C(11)
1.303(2) A, C(13)-C(14) 1.198(2) A), and the angle C(9)-
C(10)-C(11) is 176.3°. In 12, the bond distances around
the cyclobutene ring are C(9)-C(10) 1.360(3), C(10)-
C(100) 1.496(4), C(10)-C(11) 1.476(3), and C(11)-C(110)
Figure 3. Space-filling representation of 12, emphasizing the
overlap of the fluorenylidenes.
As with the 1,2-difluorenylidene-cyclobutanes reported
previously,4,5,8 their large wingspans (∼8.8 A) cause severe
overlap of the fluorenylidenes in the cyclobutene 12, such
that the molecule adopts C2 symmetry with a dihedral angle
of 51.3° between the fluorenylidene planes. The phenyls and
fluorenylidenes are twisted out of the cyclobutene plane by
32° and 35°, respectively, as depicted in the space-filling
representation in Figure 3. It is also noteworthy that the
direction of helicity of the fluorenylidenes is opposed to that
of the phenyls. This matches the thermodynamically favored
orientation found in the corresponding 1,2-difluorenyliden-
3,4-diphenylcyclobutanes.4
ꢀ
1.392(4) A.
Reactions with Cobalt and Iron Carbonyls. The Pauson-
Khand reaction of an alkyne, an alkene, and a source of CO
(commonly Co2(CO)8) to form a cyclopentenone continues
to attract attention, not merely as a powerful and versatile
(11) Kuhn, R.; Rewicki, D. Chem. Ber. 1965, 98, 2611–2618.
(12) Toda, F.; Takehira, Y. J. Chem. Soc., Chem. Commun. 1975, 174.
€
(13) Grealis, J. P.; Muller-Bunz, H.; Casey, M.; McGlinchey, M. J.
Tetrahedron Lett. 2008, 49, 1527–1530.

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Oulie et al.
678 Organometallics, Vol. 29, No. 3, 2010
Scheme 1. Reactions of the Bis(trimethylsilyl)propargylallene 2 and of the Bis(trimethylsilyl)diallene 3
Scheme 2. Reactions of Propargylallenes with Cobalt and Iron Carbonyls
synthetic approach,14 but also to clarify the mechanistic
details.15 Thus, we recently reported the first structurally
characterized example of a (μ-alkyne)(η2-alkene)penta-
carbonyldicobalt complex,16 the first intermediate in the proposed
mechanism of the PKR.17 Although intramolecular Pauson-
Khand reactions of allenynes connected through aromatic
rings have been described,18 we are unaware of any correspond-
ing reports on propargylallenes.
As shown in Scheme 2, the disilyl- and diphenylpropargyl-
allenes 2 and 9, respectively, react readily with dicobalt
octacarbonyl to form the tetrahedral alkyne-dicobalt hexa-
carbonyl clusters 13 and 14, respectively, and their structures
are shown in Figures 4 and 5. In both cases, the bulkiness of
the alkynyl-Co2(CO)6 cluster causes a bending of the allene
moiety away from linearity (167.3° in 13, 171.6° in 14), but
(14) For reviews of the Pauson-Khand reaction see: (a) Jeong, N.
Comprehensive Organometallic Chemistry III; Crabtree, R. H.; Mingos,
D. M. P. Eds.; Elsevier: Oxford, U.K., 2006; Vol. 11, pp 335-366, and
references therein. (b) Laschat, S.; Becheanu, A.; Bell, T.; Baro, A. Synlett
2005, 2547–2570. (c) Gibson, S. E.; Mainolfi, N. Angew. Chem., Int. Ed.
2005, 44, 3022–3037. (d) Bonaga, L. V. R.; Krafft, M. E. Tetrahedron 2004,
60, 9795–9833.
~
(15) (a) Yamanaka, M.; Nakamura, E. J. Am. Chem. Soc. 2001, 123,
1703–1708. (b) Robert, F.; Milet, A.; Gimbert, Y.; Konya, D.; Greene, A. E.
J. Am. Chem. Soc. 2001, 123, 5396–5400.
(17) (a) Magnus, P.; Principe, L.-M. Tetrahedron Lett. 1985, 26,
4851–4854. (b) La Belle, B. E.; Knudsen, M. J.; Olmstead, M. M.; Hope,
H.; Yanuck, M. D.; Schore, N. E. J. Org. Chem. 1985, 50, 5215-5222.
€
(16) (a) Banide, E. V.; Muller-Bunz, H.; Manning, A. R.; Evans, P.;
McGlinchey, M. J. Angew. Chem., Int. Ed. 2007, 46, 2907–2910.
€
ꢀ ꢀ ~
(18) Gonzales-Gomez, A.; Anorhbe, L.; Poblador, A.; Domınguez,
´
(b) Brusey, S. A.; Banide, E. V.; Dorrich, S.; O'Donohue, P.; Ortin, Y.;
ꢀ
M€uller-Bunz, H.; Long, C.; Evans, P.; McGlinchey, M. J. Organometallics
2009, 28, 6308–6319.
G.; Perez-Castells, J. Eur. J. Org. Chem. 2008, 1370-1377, and references
therein.

Article
Organometallics, Vol. 29, No. 3, 2010 679
Figure 6. Structure of the (η5-fluorenyl)iron complex 15. Ther-
mal ellipsoids are at 50%. Selected bond lengths (A): Fe(1)-
C(9) 2.070(3), Fe(1)-C(9a) 2.143(3), Fe(1)-C(4a) 2.202(3),
Fe(1)-C(4b) 2.244(3), Fe(1)-C(8a) 2.207(3), C(9)-C(10)
1.455(4), C(10)-C(11) 1.360(4), C(11)-C(12) 1.542(4), C(12)-
C(13) 1.556(4), C(13)-C(14) 1.338(4).
Figure 4. X-ray structure of dicobalt cluster 13. Thermal ellip-
ꢀ
soids are at 50%. Selected bond lengths (A): C(9)-C(10)
ꢀ
1.324(2), C(10)-C(11) 1.299(2), C(11)-C(12) 1.531(2), C(12)-
C(13) 1.520(2), C(13)-C(14) 1.333(2), Co(1)-Co(2) 2.4465(4),
Co(1)-C(14) 2.005(2), Co(1)-C(13) 1.988(2), Co(2)-C(14)
1.988(2), Co(2)-C(13) 1.996(2).
1965, and 1649 cm-1. This difference could indicate that the
organic carbonyl function in 15 is part of a more extended π-
system.
The structure of 15 was unambiguously determined by
X-ray crystallography and revealed that, as in 7, it possesses
an (η5-fluorenyl)iron-dicarbonyl moiety and also a second
fluorenyl substituent but now spiro-bonded to a cyclo-
butene. This four-membered ring is bonded directly to C(9)
of the complexed fluorenyl system and is also attached to the
iron atom via a dC(Ph)-C(dO)- linkage. The iron atom in
15 is not symmetrically bonded to the central ring of the
ꢀ
fluorenyl ligand, with distances ranging from 2.070(3) A, for
ꢀ
Fe(1)-C(9), to 2.244(3) A for Fe(1)-C(4b). The fluorenyl
ligand is not planar, but rather is slightly arced such that the
interplanar angle between the six-membered rings is 7°. The
iron-to-acyl-carbon distance, Fe(1)-C(35), is slightly longer
Figure 5. Structure of dicobalt cluster 14. Thermal ellipsoids
ꢀ
are at 50%. Selected bond lengths (A): C(9)-C(10) 1.320(2),
C(10)-C(11) 1.309(2), C(11)-C(12) 1.548(2), C(12)-C(13)
1.520(2), C(13)-C(14) 1.342(2), Co(1)-Co(2) 2.4530(3),
Co(1)-C(14) 1.990(2), Co(1)-C(13) 1.955(2), Co(2)-C(14)
1.953(2), Co(2)-C(13) 1.970(2).
ꢀ
ꢀ
(2.008(3) A) than the corresponding distance (1.997(5) A) in
7. Although 15 is not actually mirror-symmetric in the solid
state, NMR data indicate time-averaged Cs symmetry in
solution. To the best of our knowledge, apart from 7, there is
only one previous report of a crystallographically characteri-
zed molecule possessing an (η5-fluorenyl) unit coordinated
to iron;19 thus, 15 is only the third example of this type.
A mechanistic rationale is presented in Scheme 3, whereby
initial coordination of an Fe(CO)3 fragment was followed
either (i) by rearrangement of the (propargyl-allene)Fe-
(CO)3, 16a (R = TMS), into a silyl-vinylidene complex, 17,
that underwent cyclization to 18 and then to 7 or (ii) in the
phenyl case, 16b, by direct rearrangement to the cyclobutene
19; subsequent migration onto a terminal carbonyl group
yields the observed product, 15. Evidently, the formation of
the cyclopentadiene or cyclobutene ring depends on whether
the alkynyl substituent can migrate to form the vinylidene
intermediate, 17, as is known for trimethylsilylalkyne com-
plexes of Ru, Rh, and Ir.20
there is no evidence of loss of a carbonyl ligand, even when
heated at reflux in toluene. In the free diphenylpropargylal-
lene 9 (Figure 1) the two fluorenyl fragments are close to
parallel (dihedral angle of 7.7°), but when complexed to
Co2(CO)6 in 14 this opens up to 34.6°; in contrast, in the
disilyl-dicobalt propargylallene 13, these planes maintain
their relative orientation (dihedral angle of 4.6°).
Although 2 and 9 react with dicobalt octacarbonyl in
identical fashion, their reactions with diiron nonacarbonyl
are strikingly different. As noted already in Scheme 1, the
silyl system 2 yields a novel complex, 7, in which an
(η5-fluorenyl)Fe(CO)2 moiety is linked both directly and
via a bridging carbonyl to a cyclopentadiene ring possessing
two trimethylsilyl groups and a spiro-bonded fluorenyl sub-
stituent.9 The product, 15, from the reaction of the diphenyl
propargylallene 9 with Fe2(CO)9 (or better with Fe(CO)5 and
1
morpholine N-oxide) likewise exhibited H and 13C NMR
(19) Kirillov, E.; Kahlal, S.; Roisnel, T.; Georgelin, T.; Saillard, J.-Y.;
Carpentier, J.-F. Organometallics 2008, 27, 387–393.
spectra indicating the presence of two different fluorenyl
groups and two nonequivalent phenyl substituents, as well as
terminal and bridging Fe-13CO NMR resonances at 212.8
and 249.3 ppm, respectively. In the infrared spectrum, νCO
absorptions were found at 2017, 1961, and 1604 cm-1. In
comparison, complex 7 derived from the disilyl-propargyl-
allene 2 and iron carbonyl exhibited νCO absorptions at 2017,
(20) (a) Schneider, D.; Werner, H. Angew. Chem., Int. Ed. Engl. 1991,
30, 700–702. (b) Werner, H.; Baum, M.; Schneider, D.; Windm€uller, B.
Organometallics 1994, 13, 1089–1097. (c) Baum, M.; Windm€uller, B.;
Werner, H. Z. Naturforsch. B 1994, 49, 859–869. (d) Werner, H.; Lass,
R. W.; Gevert, O.; Wolf, J. Organometallics 1997, 16, 4077–4088. (e) Braun,
T.; M€unch, G.; Windm€uller, B.; Gevert, O.; Laubender, M.; Werner, H.
Chem.;Eur. J. 2003, 9, 2516–2530. (f) Konkol, M.; Steinborn, D.
J. Organomet. Chem. 2006, 691, 2839–2845.

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680 Organometallics, Vol. 29, No. 3, 2010
Scheme 3. Mechanisms of Reactions of Propargylallenes with Iron Carbonyl
Reaction of Fe2(CO)9 with the Phenylbromoallene 11. Since
bromoallenes are known to dimerize in the presence of metal
salts such as Cu(I),12 and allyl bromides undergo coupling
reactions with iron carbonyls,21 we decided to investigate the
reaction of the phenylbromoallene 11 with di-iron nona-
carbonyl to see whether allenyl coupling or any other pro-
cesses could be elucidated. Moreover, diallenes can cyclize
and undergo carbonyl insertions to form highly fluorescent
2,5-dialkylidene-3-cyclopentenones in the presence of iron or
cobalt carbonyls.22 By analogy, we had anticipated the for-
mation of mirror-symmetric 2,5-di(fluorenylidene)-3-cyclopen-
tenone, 20, and indeed one of the several products did have the
molecular formula C43H26O and fluoresced strongly. More-
1
over, the presence in its H and 13C NMR spectra of eight
Figure 7. Structure of the bicyclo[3.2.0]heptadienone 21. Thermal
ellipsoids are at 30%.
fluorenyl CH units, two phenyl rings, and a 13CdO resonance
at 203 ppm, together with an infrared absorption at 1704 cm-1
,
indicated 20 to be a possible product whereby the “inner” and
“outer” benzo rings would each exhibit two doublets and two
triplets. However, X-ray crystallography (Figure 7) revealed
the true answer! The molecule does indeed possess a molecular
mirror plane, but not the one anticipated. The product is the
bicyclo[3.2.0]heptadienone 21, in which two nonequivalent
spiro-bonded fluorenyls are positioned orthogonal to the
planar bicyclic system, and so each exhibits only four CH
environments. The angles at the three unsaturated carbons in
the cyclobutene ring are C(5)-C(4)-C(3) 92°, C(4)-C(3)-
C(6) 94.9°, and C(3)-C(6)-C(5) 90.9°, but the angle contain-
ing the spirofluorenyl moiety, C(4)-C(5)-C(6), is only 82.2°.
The sequence C(4)-C(3)-C(6)-C(7) is a 1,3-butadiene fragment,
and the relevant bond distances are C(4)-C(3) 1.361(2) A,
C(3)-C(6) 1.418(2) A, and C(6)-C(7) 1.356(2) A; thus, the
central bond that is common to both rings is markedly shorter
than the value of ∼1.48 A, which is more typical of a butadiene
fragment.
Scheme 4. Possible Route to 21 via a Reductive Elimination
mechanism for the formation of the bicycloheptadienone 21
must remain speculative, it could conceivably arise simply by
reductive elimination from 15, as in Scheme 4. However, the
observed long-term thermal stability of 15 at room temperature
may militate against such a process.
The bicyclic system in 21 has been reported only very
rarely, and we are unaware of any structural studies: pyroly-
sis of [perchloro-3,4-di(methylene)cyclobutene]Fe(CO)3, 22,
is reported to yield a ketone formulated as either 23a or 23b
only on the basis of its UV spectrum.23 Moreover, the
The major product of the reaction of the bromoallene 11 and
Fe2(CO)9 is the diphenylpropargylallene 9, formally derivable by
the head-to-tail coupling of 9-(phenylethynyl)fluorenyl radicals.
However, complex 15, the above-mentioned product of reaction
of 9 with iron carbonyl, was not detectable. While any proposed
(21) Davies, S. G. Organotransition Metal Chemistry: Applications to
Organic Synthesis; Pergamon Press: Oxford, 1982; pp 238-245, and
references therein.
(22) (a) Sigman, M. S.; Eaton, B. E. J. Am. Chem. Soc. 1996, 118,
11783–11788. (b) Kaldis, J. H.; McGlinchey, M. J. Tetrahedron Lett. 2002,
43, 4049–4053.
(23) Matsukura, T.; Mano, K.; Fujino, A. Bull. Chem. Soc. Jpn. 1975,
48, 2464–2469.

Article
Organometallics, Vol. 29, No. 3, 2010 681
Scheme 5. Previously Reported Bicyclo[3.2.0]heptadienones
molecule 24, an isomer of tropone, C7H6O, and formally the
“parent” compound of 23b, has been characterized in solu-
tion by NMR and can be trapped as a Diels-Alder adduct
with diphenylisobenzofuran (Scheme 5).24
Reactions of Propargylallenes with Silver Nitrate. The use
of coinage metals to promote inter- and intramolecular coupling
processes is a burgeoning area in organic/organometallic chem-
istry. Indeed, an entire recent issue of Chemical Reviews was
devoted to this important theme.25 In particular, cyclizations
of alkynyl-allenes have been effected by treatment with gold
or platinum salts, notably by Malacria’s group26-29 and more
recently by others.30 Within the past few years, the intramole-
cular coupling of alkene and alkyne units has provided direct
one-step routes to vinylcyclopentenols,26 aryl steroids,31 and
methylene-cyclopentenones,32 as well as a range of small-ring
heterocycles.33 We here describe the reactions of propargylal-
lenes with AgNO3 in the presence of methanol or water.
When the disilylpropargylallene 2 was treated with silver
nitrate in methanol at ambient temperature overnight, the
terminal trimethylsilyl substituent was eliminated, thus
forming the monosilylated propargylallene 25, whose struc-
ture is shown in Figure 8. The carbon-carbon distances in
the allenyl and alkynyl units are C(9)-C(10) 1.325(3) A,
C(10)-C(11) 1.298(3) A, and C(13)-C(14) 1.161(4) A, and
the angle C(9)-C(10)-C(11) is 173.1°.
Figure 8. Molecular structure of propargylallene 25. Thermal
ellipsoids are at 20%.
methanol together with silver nitrate, they underwent cyclization
of the allene onto the alkyne to furnish the cyclopentadienes 26
and 27, respectively, each spiro-linked to a fluorenyl and also
possessing a 9-methoxy-[9H]-fluorenyl substituent (see Figure 9).
In 27, the phenyls at C(11) and C(14) adopt torsional angles of
78.9° and 85.3°, respectively, with the cyclopentadiene ring.
Mechanistically, one can envisage initial coordination of Agþ
to the alkyne, cyclization to form the cationic five-membered
ring system, 28, and finally nucleophilic attack by methanol.
1
The H NMR spectrum of 27 reveals that, although the
As depicted in Scheme 6, when the monosilyl- and diphenyl-
propargylallenes 25 and 9 were heated at ∼50 °C for 24 h in
fluorenyl resonances between 7.6 and 7.1 ppm are clearly
resolved, the ortho and meta positions of both phenyl rings
are markedly broadened at ambient temperature (see Figure 10);
evidently the phenyls are in sterically encumbered sites and
exhibit slowed rotation on the NMR time-scale. This severe
steric hindrance (see Figure 11) may account for the fact that
the incoming nucleophile attacks the diphenyl cation 28b at
the fluorenyl C(9) position when one might have assumed
that positive charge would be better localized at the benzylic
center rather than forming an antiaromatic fluorenyl cation.
The reactions of 25 and 9 with AgNO3 in aqueous acetone,
to give 29 and 30, respectively, proceed analogously in that
the products contain a 9-hydroxy-9H-fluorenyl group
bonded to a cyclopentadiene bearing a spiro-bonded fluo-
rene. However, in the diphenyl system, quenching of the
intermediate cation, 28b, with water, rather than methanol,
yields the alcohol 30 (Figure 12a) only as a minor product;
the major product (Figure 12b) is the (dispirofluorenyl)-
dihydrobenzpentalene 31, resulting from Friedel-Crafts
alkylation of the adjacent phenyl ring.
(24) Breslow, R.; Oda, M.; Sugimoto, T. J. Am. Chem. Soc. 1974, 96,
1639–1640.
(25) Special Issue: Coinage Metals in Organic Synthesis. (a) Silver:
Weibel, J.-M.; Blanc, A.; Pale, P. Chem. Rev. 2008, 108, 3149–3173.
ꢀ
~
(b) Gold: Jimenez-Nꢀunez, E.; Echavarren, A. M. Chem. Rev. 2008, 108,
3326–3350.
(26) Zriba, R.; Gandon, V.; Aubert, C.; Fensterband, L.; Malacria,
M. Chem.;Eur. J. 2008, 14, 1482–1491.
(27) Aubert, C.; Buisine, O.; Malacria, M. Chem. Rev. 2002, 102,
813–834.
(28) Cadran, N.; Cariou, K.; Herve, G.; Aubert, C.; Fensterbank, L.;
Malacria, M.; Marco-Contelles, J. J. Am. Chem. Soc. 2004, 126,
3408–3409.
(29) Llerena, D.; Buisine, O.; Aubert, C.; Malacria, M. Tetrahedron
1998, 54, 9373–9392.
(30) (a) Marion, N.; Nolan, S. P. Angew. Chem., Int. Ed. 2007, 46,
2750–2752. (b) Hashmi, A. S. K.; Rudolph, M.; Heck, J.; Frey, W.;
ꢀ
Bats, J. W.; Hamzic, M. Angew. Chem., Int. Ed. 2009, 48, 5848–5852. (c)
ꢀ
~
Jimenez-Nꢀunez, E.; Raducan, M.; Lauterbach, T.; Molawi, K.; Solario, C. R.;
Echavarren, A. M. Angew. Chem., Int. Ed. 2009, 48, 6152–6155.
(31) Petit, M.; Aubert, C.; Malacria, M. Tetrahedron 2006, 62, 10582–
10593.
(32) Kato, K.; Kobayashi, T.; Fujinami, T.; Motodate, S.; Kusakabe,
T.; Mochida, T.; Akita, H. Synlett 2008, 1081–1085.
(33) Alcaide, B.; Almendros, P.; Aragoncillo, C. Chem.-Eur. J. 2002,
8, 1719–1729.
To conclude, the proximity of the allenyl and alkynyl
moieties in the trimethylsilyl- or phenyl-substituted propar-
gylallenes 2, 25, and 9 facilitates metal-mediated interactions

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Oulie et al.
682 Organometallics, Vol. 29, No. 3, 2010
Figure 9. Molecular structures of the 9-(methoxyfluorenyl)(trimethylsilyl)cyclopentadiene 26 and the 9-(methoxyfluorenyl)diphenyl-
ꢀ
cyclopentadiene 27. Thermal ellipsoids are shown at 50%. Selected bond lengths (A) for 26: C(9)-C(10) 1.506(3), C(10)-C(11)
1.353(3), C(11)-C(12) 1.535(3), C(12)-C(13) 1.510(3), C(13)-C(14) 1.321(3) C(14)-C(10) 1.474(3); for 27: C(9)-C(10) 1.508(3),
C(10)-C(11) 1.341(3), C(11)-C(12) 1.529(3), C(12)-C(13) 1.489(3), C(13)-C(14) 1.328(3) C(14)-C(10) 1.488(3), C(11)-C(23)
1.485 (3).
Figure 10. Aromatic region of the 500 MHz 1H NMR spectrum of the 9-(methoxyfluorenyl)diphenylcyclopentadiene 27, illustrating
the clearly resolved fluorenyl peaks from 7.6 to 7.1 ppm and the very broad phenyl resonances between 7.0 and 6.0 ppm.
Scheme 6. Silver-Promoted Cyclization of Propargylallenes
between these functional groups. Iron carbonyl-promoted
cyclizations to form the cyclopentadiene or cyclobutene
complex 7 or 15 are controlled by the character of the alkynyl
substituent in the initial Fe(CO)3 complex, 16, whereby the
trimethylsilyl, but not the phenyl, undergoes rearrangement
to form a vinylidene complex. Current work is focused on

Article
Organometallics, Vol. 29, No. 3, 2010 683
trapping the propargylallene metal complex prior to cycliza-
tion. Propargylallenes react with silver(I) to yield cyclo-
pentadienes and also a dihydrobenzpentalene; extension of
this to other polyalkynyl allenes is under investigation. The
preliminary study of the organometallic chemistry of bromo-
allenes demonstrates the potential for novel cyclization pro-
cesses to be uncovered and will be the subject of a future report.
solution was stirred overnight, after which time a solution of
saturated NH4Cl was added, the THF was removed, and the residue
was washed with water. The organic layer was extracted using ethyl
acetate, washed with brine, and dried over MgSO4, and the solvent
removed in vacuo. The residual solid was purified by chromato-
graphy on a silica column using dichloromethane/pentane. The
yellow-orange powder was washed once with a dichloromethane/
pentane mixture, then three times with pure pentane to give the
desired product, 9 (850 mg, 1.58 mmol; 42%), as a white-yellow
1
Experimental Section
powder, mp 284-286 °C. H NMR (600 MHz, CDCl3): δ 7.82
(pseudo t, J = 7.5 Hz, 2H, H1, H8), 7.81 (pseudo t, J = 7.5 Hz, 2H,
H15, H22), 7.79 (d, J = 7.5 Hz, 2H, H4, H5), 7.71 (d, J = 7.5 Hz, 2H,
H18, H19), 7.42-7.35 (m, 8H, H2, H3, H6, H7, H16, H17, H20, H21),
7.06 (t, J = 7.5 Hz, 1H, H32), 7.03 (t, J = 7.5 Hz, 1H, H26), 6.97 (t,
J = 7.5 Hz, 2H, H25, H27), 6.96 (t, J = 7.5 Hz, 2H, H31, H33), 6.90
(d, J = 8.0 Hz, 2H, H24, H28), 6.83 (d, J = 8.0 Hz, 2H, H30, H34).
13C NMR (151 MHz, CDCl3): δ 204.2 (C10), 146.9 (C18a, C18b),
140.5 (C12a, C22a), 139.1 (C4a, C4b), 138.1 (C8a, C9a), 133.9 (C23),
131.7 (C30, C34), 128.7, 128.3, 128.2, 127.4 (C2, C3, C6, C7, C16, C17,
C20, C21), 128.5 (C24, C28), 127.9, 127.89 (C25, C27, C31, C33), 127.8,
127.7 (C26, C32), 125.5 (C15, C22), 123.2 (C29), 123.1 (C1, C8), 120.4
(C18, C19), 120.3 (C4, C5), 118.4, 109.4 (C9, C11), 89.4 (C13), 83.00
(C14), 54.6 (C12). HRMS: calcd for C42H27 [M þ Hþ], 531.2090;
found, 531.2113. A sample for an X-ray crystal structure determina-
tion was obtained by crystallization from dichloromethane/pentane.
Preparation of 3,4-Di(fluorenyliden)-1,2-diphenylcyclobutene
(12). 3,3-(Biphenyl-2,20-diyl)-1-phenyl-1-(9-phenylethynyl)-9H-
fluorenylallene (9) (250 mg, 0.471 mmol) was dissolved in
toluene (10 mL) and heated for 5 h at reflux. The solvent was
removed in vacuo and the residual solid purified by chromato-
graphy on a silica column using dichloromethane/pentane to
yield 12 (50 mg, 0.094 mmol; 20%) as an orange powder,
mp 266-268 °C. 1H NMR (500 MHz, CDCl3): δ 7.76 (d, J =
7.5 Hz, 2H, H4), 7.70 (d, J = 7.5 Hz, 2H, H5), 7.57 (d, J =
7.8 Hz, 2H, H8), 7.37 (t, J = 7.5 Hz, 2H, H15), 7.31 (t, J = 7.5 Hz,
4H, H14, H16), 7.28 (t, J = 7.5 Hz, 2H, H3), 7.27 (d, J = 7.5 Hz, 4H,
H13, H17), 7.15 (t, J = 7.5 Hz, 2H, H6), 6.88 (t, J = 7.5 Hz, 2H, H2),
6.85(d, J=7.5Hz, 2H, H1), 6.81(t, J= 7.5 Hz, 2H, H7). 13CNMR
(125 MHz, CDCl3): δ 157.6 (C11), 145.0 (C10), 140.0 (C4b), 140.4
(C4a), 137.9 (C8a), 137.2 (C9a), 133.0 (C12), 128.7 (C8), 128.6 (C13,
C17), 128.1 (C14, C16), 127.7 (C15), 127.6 (C1), 127.6 (C9), 127.2 (C3),
127.1 (C6), 126.4 (C7), 125.6 (C2), 119.3 (C4), 119.1 (C5). HRMS:
calcd for C42H27 [Mþ Hþ], 531.2121; found, 531.2113. A sample for
an X-ray crystal structure determination was obtained by crystal-
lization from dichloromethane/pentane.
General Methods. All reactions were carried under a nitrogen
atmosphere, and solvents were dried by standard procedures. 1H
and 13C NMR spectra were recorded on Varian 300, 400, 500, or
600 MHz spectrometers. Assignments were based on standard
two-dimensional NMR techniques (1H-1H COSY, 1H-13C
HSQC, and HMBC, NOESY). Electrospray mass spectrometry
was performed on a Micromass Quattro microinstrument.
Infrared spectra were recorded on a Perkin-Elmer Paragon
1000 FT-IR spectrometer and were calibrated with polystyrene.
Merck silica gel 60 (230-400 mesh) or alumina was used for
flash chromatography. Melting points were determined on an
Electrothermal ENG instrument and are uncorrected. Elemen-
tal analyses were carried out by the Microanalytical Laboratory
at University College Dublin. 3,3-(Biphenyl-2,20-diyl)-1-tri-
methylsilyl-1-{9-[(trimethylsilyl)ethynyl]-9H-fluorenyl}allene, 2,
and 3,3-(biphenyl-2,20-diyl)-1-bromo-1-phenylallene, 11, were pre-
pared as previously described.8,9
Preparation of 3,3-(Biphenyl-2,20-diyl)-1-phenyl-1-{9-[(phenyl-
ethynyl]-9H-fluorenyl}allene (9). 3,3-(Biphenyl-2,20-diyl)-1-bromo-
1-phenylallene (11) (2.6 g, 7.5 mmol) was dissolved in dry THF
(50 mL) and then added dropwise to a solution of BuLi (2.2 mL,
1.7 M in hexane, 3.75 mmol) in dry THF (10 mL) at -78 °C. This
Preparation of [3,3-(Biphenyl-2,20-diyl)-1-trimethylsilyl-
1-{9-[(trimethylsilylethynyl]-9H-fluorenyl}allene]Co2(CO)6 (13).
Co2(CO)8 (183 mg, 0.535 mmol) was added to a solution of
bis(trimethylsilyl)propargylallene 2 (280 mg, 0.535 mmol) in
degassed pentane (50mL). The brown-yellow solutionwas stirred
Figure 11. Space-filling representation of the 9-(methoxy-
fluorenyl)diphenylcyclopentadiene 27, emphasizing the steri-
cally crowded phenyl environments.
Figure 12. Molecular structures of (a) the cyclopentadiene 30 and (b) the dihydrobenzpentalene 31. Thermal ellipsoids are shown at
ꢀ
20% and 50%, respectively. Selected bond lengths (A) for 30: C(9)-C(10) 1.515(2), C(10)-C(11) 1.343(2), C(11)-C(12) 1.533(2),
C(12)-C(13) 1.497(2), C(13)-C(14) 1.329(2), C(14)-C10 1.493(2), C(11)-C(23) 1.487(2); for 31: C(9)-C(10) 1.515(3), C(10)-C(11)
1.333(3), C(11)-C(12) 1.514(3), C(12)-C(13) 1.528(3), C(13)-C(14) 1.349(3), C(14)-C10 1.465(3), C(9)-C(24) 1.520(4), C(23)-C-
(24) 1.415(3), C(11)-C(23) 1.456(3).

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Oulie et al.
684 Organometallics, Vol. 29, No. 3, 2010
for 15 min and turned dark red. The crude was purified by
chromatography on a silica column using ether/pentane to yield
13 (410 mg, 0.51 mmol; 95%) as a dark red powder. H NMR
by chromatography on a silica column using dichloromethane/
pentane to yield 21 (34 mg, 0.06 mmol; 7%) as a bright yellow
powder. 1H NMR (500 MHz, CDCl3): δ 8.00 (d, J = 7.6 Hz, 2H,
fluorenyl-A), 7.95 (d, J = 7.6 Hz, 2H, fluorenyl-B), 7.63 (d, J =
7.5 Hz, 2H, fluorenyl-A), 7.53 (t, J = 7.6 Hz, 2H, fluorenyl-A),
7.50 (t, J = 7.6 Hz, 2H, fluorenyl-B), 7.49 (d, J = 7.6 Hz, 2H,
fluorenyl-B), 7.38 (t, J = 7.6 Hz, 2H, fluorenyl-B), 7.36 (t, J =
7.6 Hz, 2H, fluorenyl-A), 7.24 (dd, J = 7.5, 1.9 Hz, 2H, phenyl-B
o-H), 7.07 - 7.00 (m, 3H, phenyl-B m/p-H), 6.97 (t, J = 7.4 Hz,
1H, phenyl-A p-H), 6.85 (t, J = 7.7 Hz, 2H, phenyl-A m-H),
6.24 (d, J = 7.6 Hz, 2H, phenyl-A o-H). 13C NMR (75 MHz,
CDCl3): δ 203.3 (CdO), 180.2, 153.0 (C3, C6), 146.4 (phenyl-A
ipso-C), 143.5, 142.9, 142.4, 141.0 (fluorenyl C), 130.9, 130.7
(C4, C7), 129.5 (fluorenyl-A CH), 129.3 (phenyl-A p-C), 128.8
(fluorenyl-B CH), 128.7 (phenyl-A m-C), 128.5 (phenyl-B m-C),
128.3 (fluorenyl-A CH), 128.2 (fluorenyl-B CH), 127.8 (phenyl-
B p-C), 127.5 (phenyl-B o-C), 127.2 (phenyl-A o-C), 124.5
(fluorenyl-A CH), 123.6 (fluorenyl-B CH), 121.6 (phenyl-B
ipso-C), 121.0 (fluorenyl-B CH), 120.9 (fluorenyl-A CH),
68.69, 65.09 (C2, C5). IR (liquid, CH2Cl2): 1704 cm-1 (CdO).
1
(400 MHz, C6D6): δ 8.06 (d, J = 7.4 Hz, 4H), 7.66 (d, J = 7.5 Hz,
2H), 7.44 (d, J= 7.2 Hz, 2H), 7.38 (t, J = 7.2Hz, 2H), 7.26(t, J =
7.9 Hz, 2H), 7.25 (t, J = 7.4 Hz, 2H), 7.20 (td, J = 7.4, 1.0 Hz,
2H), 0.12 (s, 9H, TMS), -0.42 (s, 9H, TMS). 13C NMR (101
MHz, C6D6): δ 201.7 (C10), 200.3 (brd, Co-CO), 152.3, 141.2,
139.1, 138.8 (fluorenyl C), 129.4, 128.3, 127.9, 127.0, 126.5, 123.6,
120.9, 120.7 (fluorenyl CH), 117.7, 110.6, 108.8, 82.4 (C9, C11,
C13, C14), 62.1 (C12), 1.8 (Si(CH3)3), 0.6 (Si(CH3)3). Anal. Calcd
for C42H34Co2O6Si2: C, 62.37; H, 4.24; Co, 14.57. Found: C,
62.20; H, 4.48; Co, 14.30. A sample for an X-ray crystal struc-
ture determination was obtained by crystallization from ether/
pentane.
Preparation of [3,3-(Biphenyl-2,20-diyl)-1-phenyl-1-{9-[(phenyl-
ethynyl]-9H-fluorenyl}allene]Co2(CO)6 (14). Co2(CO)8 (900 mg,
2.6 mmol) was added to a solution of diphenyl propargylallene 9
(480 mg, 0.905 mmol) in dry degassed THF (20 mL). The black
solution was stirred overnight. The solvent was removed in vacuo
and the residual solid purified by chromatography on a silica
column using dichloromethane/pentane to yield 14 (335 mg, 0.41
mmol; 45%) as a dark red powder. 1H NMR (500 MHz, C6D6): δ
7.97 (d, J = 6.3 Hz, 2H), 7.88 (d, J = 6.0 Hz, 2H), 7.51 (d, J =
6.5 Hz, 2H), 7.46 (d, J = 6.0 Hz, 2H), 7.42 (d, J = 6.4 Hz, 2H),
7.22-7.07 (m, 8H), 6.98 (d, J = 4.6 Hz, 2H), 6.88-6.76 (m,
3H), 6.68-6.55 (m, 3H). 13C NMR (101 MHz, C6D6): δ 203.2
(C10), 197.4 (Co-CO), 149.9, 138.7, 137.7, 136.6 (fluorenyl C),
137.4, 135.8 (C23, C29), 127.9, 127.1, 126.7, 126.3, 126.1, 126.0,
125.8, 125.6, 125.2, 124.9, 121.9, 118.7, 118.4 (aromatic CH),
117.6, 109.3, 103.8, 96.7 (C9, C11, C13, C14), 61.7 (C12). Anal.
Calcd for C48H26Co2O6: C, 70.60; H, 3.21; Co, 14.43. Found: C,
70.40; H, 3.46; Co, 14.20. A sample for an X-ray crystal structure
determination was obtained by crystallization from dichloro-
methane/pentane.
Anal. Calcd for C43H26O 0.9CH2Cl2: C, 83.02; H, 4.41. Found:
3
C, 83.28; H, 4.71. A sample for an X-ray crystal structure
determination was obtained by crystallization from dichloro-
methane/pentane.
Preparation of 3,3-(Biphenyl-2,20-diyl)-1-trimethylsilyl-1-{9-
[(ethynyl]-9H-fluorenyl}allene (25). To a solution of bis(tri-
methylsilyl)propargylallene (2) (500 mg, 0.96 mmol) in degassed
ether/methanol/water (32 mL/18 mL/4 mL) was added silver
nitrate (120 mg, 0.70 mmol) as a powder at once. After stirring
overnight in the dark, water was added and the mixture was
extracted with ether. The organic layers were combined, washed
with water and brine, dried over MgSO4, filtered, and concen-
trated to give a slightly yellow powder. The powder was washed
with a small amount of ether to give 25 (350 mg, 0.77 mmol;
81%) as a white powder. 1H NMR (400 MHz, CDCl3): δ
7.86-7.76 (m, 8H), 7.50-7.45 (m, 4H), 7.44-7.38 (m, 4H),
2.05 (s, 1H, CtCH), -0.44 (s, 9H, TMS). 13C NMR (125 MHz,
CDCl3): δ 204.7 (C10), 147.2, 140.3, 138.7, 138.0 (fluorenyl C),
128.8, 128.3, 127.1, 126.9, 125.5, 122.3, 120.3, 120.2 (fluorenyl
CH), 110.7, 105.4 (C9, C11), 89.4, 84.1 (C13, C14), 70.3 (C12),
-0.1 (Si(CH3)3). IR (liquid, CH2Cl2): 3300 cm-1 (CtC), 1920
cm-1 (CdCdC). ESMS: calcd for C33H26Si [M þ Hþ], 451.19;
found, 451.21. A sample for X-ray crystal structure determina-
tion was obtained by crystallization from dichloromethane/
pentane.
Reaction of 9 with Iron Carbonyl. To a solution of
3,3-(biphenyl-2,20-diyl)-1-phenyl-1-(9-phenylethynyl)-9H-fluor-
enyl-allene (9) (0.30 g, 0.57 mmol) dissolved in dry THF (16 mL)
was added Fe(CO)5 (0.08 mL, 0.62 mmol). The solution was
cooled to -20 °C, and morpholine N-oxide (72.9 mg, 0.622
mmol) dissolved in dry THF (14 mL) was added dropwise. The
solution was stirred for 1 h at -20 °C and a further 2.5 h at room
temperature. The solvent was removed in vacuo and the residual
solid purified by chromatography on a silica column using
dichloromethane/pentane to yield 15 (49 mg, 0.073 mmol;
1
Preparation of 9-(2-Trimethylsilylspiro[cyclopenta[2,4]diene-
1,90-[9H]fluorene]-3-yl)-9-methoxy-9H-fluorene (26). AgNO3
(220 mg, 1.30 mmol) was added to a solution of bis(trimethyl-
silyl)propargylallene, 2 (500 mg, 0.956 mmol), in degassed
methanol (20 mL); the mixture was heated at 55 °C for 24 h.
After evaporation of the methanol, the residual solid was
dissolved in ether, washed with water and brine, dried over
MgSO4, and concentrated to give 26 (300 mg, 0.62 mmol; 65%)
as a yellow powder. 1H NMR (500 MHz, CDCl3): δ 7.76 (d, J =
8.0 Hz, 2H, H4, H5), 7.74 (d, J = 8.0 Hz, 2H, H18, H19), 7.55 (dd,
J = 7.2, 0.6 Hz, 2H, H1, H8), 7.47 (td, J = 7.4, 1.4 Hz, 2H, H3,
H6), 7.43 (td, J = 7.3, 1.1 Hz, 2H, H2, H7), 7.34 (td, J = 7.5, 0.8
Hz, 2H, H17, H20), 7.23 (t, J = 7.5 Hz, 2H, H16, H21), 7.04 (d,
J = 7.5 Hz, 2H, H15, H22), 5.81 (d, J = 5.0 Hz, 1H, H13), 5.36 (d,
J = 5.0 Hz, 1H, H14), 2.86 (s, 3H, OCH3), -0.17 (s, 9H, TMS).
13C NMR (126 MHz, CDCl3): δ 159.4 (C10), 145.6 (C8a, C9a),
145.3 (C13), 144.2 (C12a, C22a), 142.5 (C18a, C18b), 141.8 (C11),
141.4 (C4a, C4b), 131.5 (C14), 129.5 (C3, C6), 128.6 (C2, C7), 127.4
(C17, C20), 127.3 (C16, C21), 125.3 (C1, C8), 123.0 (C15, C22),
120.4 (C18, C19), 120.2 (C4, C5), 89.6 (C9), 76.5 (C12), 50.0
(OCH3), 1.9 (Si(CH3)3). ESMS: calcd for C34H30OSi [M -
12%) as an orange powder. H NMR (500 MHz, CDCl3): δ
8.13 (d, J = 8.4 Hz, 2H, H4, H5), 7.75 (d, J = 8.5 Hz, 2H, H1, H8),
7.68 (d, J = 8.4 Hz, 4H, H15, H18, H19, H22), 7.51 (t, J = 7.7 Hz,
2H, H2, H7), 7.46 (t, J = 7.7 Hz, 2H, H3, H6), 7.37, 7.28 (2 td, J =
7.4, 1.0 Hz, 4H, H16, H17, H20, H21), 7.20 (t, J = 7.1 Hz, 1H, H26),
7.12 (t, J = 7.7 Hz, 2H, H25, H27), 7.09 (dd, J = 8.4, 1.3 Hz, 2H,
H24, H28), 6.75 (t, J = 7.4 Hz, 1H, H32), 6.63 (t, J = 7.7 Hz, 2H,
H31, H33), 6.24(dd, J = 8.2, 1.1Hz, 2H, H30, H34). 13CNMR (126
MHz, CDCl3): δ 249.3 (Fe μ-CO), 212.8 (Fe-CO), 162.3 (C10),
154.1 (C11), 145.1, 141.2 (C12a, C18a, C18b, C22a), 135.8 (C13),
134.4 (C29), 133.8 (C14), 131.6 (C23), 129.8 (C26), 129.5 (C2, C7),
129.1 (C25, C27), 128.6 (C30, C34), 128.4, 127.7 (C16, C17, C20, C21),
127.7 (C24, C28), 126.9 (C31, C33), 126.5 (C3, C6), 126.3 (C32),
124.2 (C1, C8), 124.1 (C4, C5), 123.6, 120.3 (C15, C18, C19, C22),
108.8 (C8a, C9a), 98.2 (C4a, C4b), 67.0 (C12), 60.0 (C9). IR (liquid,
CH2Cl2): ν 2017, 1961 cm-1 (terminal CdO), 1604 cm-1
(bridging CdO). HRMS: calcd for C42H27Fe(CO)3 [M þ Hþ],
671.1332; found, 671.1310. A sample for an X-ray crystal struc-
turedeterminationwas obtainedbycrystallizationfromdichloro-
methane.
Preparation of Bicyclo[3.2.0]heptadienone (21). Diiron-non-
acarbonyl (1.93 g, 5.30 mmol) and 3,3-(biphenyl-2,20-diyl)-1-
bromo-1-phenylallene (11) (300 mg, 0.87 mmol) were dissolved
in dry THF (20 mL) and stirred for 3 days at room temperature.
The solvent was removed in vacuo and the residual solid purified
OCH3-], 451.20; found, 451.25. Anal. Calcd for C34H30OSi
3
0.5MeOH: C, 83.09; H, 6.47. Found: C, 82.72; H, 6.19. A sample
suitable for an X-ray crystal structure determination was ob-
tained by crystallization from ether/dichloromethane.

Article
Organometallics, Vol. 29, No. 3, 2010 685
Table 1. Crystallographic Data for 9, 12, 13, 14, and 15
9
12
13
14
15
formula
M
cryst syst
space group
a [A]
C42H26
530.63
triclinic
P1 (#2)
8.8808(10)
8.9416(10)
19.076(2)
87.529(2)
78.066(2)
72.726(2)
1419.9(3)
2
C42H26 CH2Cl2
3
C42H34Si2Co2O6
808.73
C48H26Co2O6
816.55
triclinic
(C45H27FeO3)2 CH2Cl2 (H2O)0.3
3
3
615.55
1430.45
orthorhombic
P212121 (#18)
14.220(2)
8.4832(12)
12.4919(18)
90
90
90
1507.0(4)
2
1.357
monoclinic
P21/n (#14)
9.2714(17)
20.869(4)
20.063(4)
90
95.647(4)
90
3862.9(12)
4
1.391
monoclinic
P21/c (#14)
25.699(2)
13.8982 (13)
19.1186(17)
90
99.035(3)
90
6736.1(11)
4
1.410
P1 (#2)
9.8101(4)
18.4399(8)
20.9994(9)
103.436(1)
93.299((1)
92.751(1)
3681.3(3)
4
1.473
100(2)
0.954
1664
b [A]
c [A]
R [deg]
β [deg]
γ [deg]
V [A3]
Z
F
T [K]
calcd [g cm-3
]
1.245
100(2)
0.071
556
100(2)
0.248
640
100(2)
0.967
1664
100(2)
0.571
2946
μ [mm-1
F(000)
]
θ range for data collection [deg]
index ranges
2.18 to 25.00
-10 e h e 10
-10 e k e 10
-22 e l e 22
22 612
4992
0.0311
4992/0/483
1.63 to 26.42
-17 e h e 17
-10 e k e 10
-15 e l e 15
13 075
3098
0.0436
3098/0/204
1.41 to 28.30
-12 e h e 12
-27 e k e 27
-26 e l e 26
38 946
9585
0.0360
9585/0/605
1.14 to 30.50
-13 e h e 13
-26 e k e 26
-29 e l e 29
86 123
22 081
0.0333
22 081/0/1217
1.61 to 22.08
-27 e h e 27
-14 e k e 14
-20 e l e 20
40 546
8285
0.0549
8285/377/920
reflns measd
indep reflns
Rint
data/restraints/params
final R values [I > 2θ(I)]:
R1
wR2
R values (all data):
0.0381
0.0907
0.0431
0.0884
0.0355
0.0868
0.0363
0.0886
0.0375
0.0853
R1
wR2
0.0448
0.0950
1.043
0.0513
0.0912
1.068
0.0439
0.0915
1.049
0.0451
0.0929
1.048
0.0471
0.0902
1.023
GOF on F2
Preparation of 9-(2,4-Diphenylspiro[cyclopenta[2,4]diene-1,90-[9H]-
fluorene]-3-yl)-9-methoxy-9H-fluorene (27). AgNO3 (170 mg,
1.00 mmol) was added to a solution of diphenylpropargylallene
9 (330 mg, 0.565 mmol) in degassed methanol (20 mL); the
mixture was heated at 45 °C for 24 h. After evaporation of the
methanol, the residual solid was dissolved in ether, washed with
water and brine, dried over MgSO4, concentrated, and recrystal-
lized from ether/dichloromethane to give 27 (125 mg, 0.22 mmol;
39%) as yellow crystals. 1H NMR (500 MHz, CDCl3): δ 7.58 (d,
J = 7.4 Hz, 2H, H1, H8), 7.54 (d, J = 7.4 Hz, 2H, H18, H19), 7.38
(d, J = 7.4 Hz, 2H, H15, H22), 7.34 (t, J = 7.3 Hz, 2H, H2, H7),
7.29 (td, J = 7.3, 1.3 Hz, 2H, H16, H21), 7.26 (td, J = 7.3, 1.3 Hz,
2H, H17, H20), 7.22 (t, J = 7.3 Hz, 2H, H3, H6), 7.11 (d, J =
7.4 Hz, 2H, H4, H5), 6.94-6.58 (m, 8H, phenyl H), 6.38-6.13 (m,
2H, phenyl H), 5.84 (s, 1H, H13), 2.22 (s, 3H, OCH3). 13C NMR
(126 MHz, CDCl3): δ 149.5, 147.7 (C10, C11), 145.4 (C8a, C9a),
142.9 (C12a, C22a), 142.6 (C18a, C18b), 142.3(C14), 142.0(C4a, C4b),
137.2 (C13), 129.0 (C3, C6), 128.9 (4C, phenyl o/m-C), 127.9 (C2,
C7), 127.6 (C17, C20), 127.2 (C16, C21), 126.4 (2C, phenyl o/m-C),
125.9 (2C, phenyl o/m-C), 125.5 (1C, phenyl p-C), 125.4 (1C,
phenyl p-C), 125.3 (C1, C8), 123.7 (C15, C22), 120.3 (C18, C19),
119.9 (C4, C5), 88.3 (C9), 72.9 (C12), 49.5 (OCH3). ESMS: calcd
for C43H30O [M - OCH3-], 531.21; found, 531.27. HRMS: calcd
for C43H30O [M þ Hþ], 563.2375; found, 563.2387. A sample
suitable for an X-ray crystal structure determination was ob-
tained by crystallization from ether/dichloromethane.
Preparation of 9-(2-Trimethylsilylspiro[cyclopenta[2,4]diene-
1,90-[9H]fluorene]-3-yl)-9H-fluoren-9-ol (29). AgNO3 (40 mg,
0.235 mmol) was added to a solution of bis(trimethylsilyl)-
propargylallene 9 (330 mg, 0.565 mmol) in a degassed water/
acetone/THF (5 mL/20 mL/2 mL) solution; the mixture was
heated at 55 °C for 24 h in the dark. After evaporation of the
solvent, the residual solid was dissolved in ether, washed with
water and brine, dried over MgSO4, and concentrated. The
residual solid was purified by chromatography on a silica
column using dichloromethane/pentane to yield 29 (60 mg,
0.13 mmol; 34%) as a yellow powder. 1H NMR (400 MHz,
CDCl3): δ 7.72 (d, J = 7.0 Hz, 2H, H18, H19), 7.71 (d,
J = 7.0 Hz, 2H, H1, H8), 7.60 (dd, J = 7.0, 0.9 Hz, 2H, H4,
H5), 7.44 (td, J = 7.4, 1.2 Hz, 2H, H2, H7), 7.41 (td, J = 7.4, 1.2
Hz, 2H, H3, H6), 7.33 (td, J = 7.5, 1.0 Hz, 2H, H17, H20), 7.22
(td, J = 7.5, 1.0 Hz, 2H, H16, H21), 7.04 (d, J = 7.5 Hz, 2H, H15,
H22), 5.81 (d, J = 5.0 Hz, 1H, H13), 5.35 (d, J = 4.9 Hz, 2H,
H14), 2.29 (s, 1H, OH), -0.16 (s, 9H, TMS). 13C NMR (101
MHz, CDCl3): δ 158.7 (C10), 149.2 (C8a, C9a), 145.5 (C13), 144.0
(C18a, C18b), 142.5 (C12a, C22a), 142.1 (C11), 140.0 (C4a, C4b),
131.7 (C14), 129.5 (C2, C7), 128.9 (C3, C6), 127.5 (C17, C20), 127.3
(C16, C21), 124.7 (C4, C5), 123.0 (C15, C22), 120.4 (C18, C19), 84.3
(C9), 76.7 (C12), 2.0 (Si(CH3)3). ESMS: calcd for C33H28OSi [M
- OH-], 451.19; found, 451.23.
Preparation of 9-(2,4-Diphenylspiro[cyclopenta[2,4]diene-
1,90-[9H]fluorene]-3-yl)-9H-fluoren-9-ol (30) and Its Correspond-
ing Dihydrobenzpentalene (31). AgNO3 (40 mg, 0.235 mmol) was
added to a solution of the diphenylpropargylallene 9 (200 mg,
0.383 mmol) in a degassed water/acetone/THF (5 mL/20 mL/
2 mL) solution; the mixture was heated at 55 °C for 24 h in the
dark. After evaporation of the solvent, the residual solid was
dissolved in ether, washed with water and brine, dried over
MgSO4, and concentrated. The residual solid was purified by
chromatography on a silica column using dichloromethane/
pentane to yield 30 (20 mg, 0.036 mmol; 10%) as a yellow
powder and its corresponding dihydrobenzpentalene, 31
(150 mg, 0.283 mmol; 74%), as a yellow powder. Data for 30:
1H NMR (400 MHz, CDCl3): δ 7.61 (d, J = 7.4 Hz, 2H, H1, H8),
7.57 (dd, J = 7.0, 1.4 Hz, 2H, H18, H19), 7.43 (d, J = 7.0 Hz, 2H,
H15, H22), 7.36 (t, J = 7.2 Hz, 2H, H2, H7), 7.35 (t, J = 7.0 Hz,
2H, H16, H21), 7.31 (td, J = 7.3, 1.4 Hz, 2H, H17, H20), 7.25 (t,
J = 7.4 Hz, 2H, H3, H6), 7.14 (d, J = 7.5 Hz, 2H, H4, H5), 7.02 -
6.94 (m, 3H, 1 phenyl p-H, 2 phenyl o/m-H), 6.94-6.83 (m, 3H,
1 phenyl p-H, 2 phenyl o/m-H), 6.68 (t, J = 6.9 Hz, 2H, phenyl
o/m-H), 6.20-6.10 (m, 2H, phenyl o/m-H), 5.90 (s, 1H, H13),
2.21 (s, 1H, OH). 13C NMR (101 MHz, CDCl3): δ 149.4 (C10 or
C11), 148.5 (C8a, C9a), 147.3 (C10 or C11), 143.1 (C14), 142.7
(C18a, C18b), 142.3 (C12a, C22a), 140.9 (C4a, C4b), 137.2 (C13),
136.0 (phenyl ipso-C), 129.2 (phenyl o/m-C), 129.0 (C3, C6),
128.9 (phenyl o/m-C), 128.1 (C2, C7), 127.9 (C17, C20), 127.4

ꢀ
Oulie et al.
686 Organometallics, Vol. 29, No. 3, 2010
Table 2. Crystallographic Data for 21, 25, 26, 27, 30, and 31
21
25
26
27
30
31
formula
M
cryst syst
space group
a [A]
C
643.56
44H26O CH2Cl2
3
C33H26Si
450.63
C34H30SiO
482.67
triclinic
C43H30
562.67
O
(C42H28O)2 CH3OH
3
C42H26
530.63
1129.33
triclinic
P1 (#2)
monoclinic
P21/n (#14)
10.8528(8)
21.7590(15)
13.7075(10)
90
90.513(2)
90
3236.8(4)
4
1.321
orthorhombic
Pnma (#62)
19.0833(15)
16.0230(12)
8.2882(6)
90
90
90
2534.3(3)
4
1.181
monoclinic
P21/n (#14)
8.4024(12)
23.421(3)
15.892(2)
90
91.641(4)
90
3126.2(8)
4
1.195
monoclinic
P21/c (#14)
22.645(4)
17.311(3)
14.296(2)
90
90.186(4)
90
5604.3(16)
8
1.258
P1 (#2)
12.1774(13)
15.1205(16)
16.2574(17)
104.410(2)
90.132(2)
112.246(2)
2667.9(5)
4
1.202
100(2)
0.113
1024
9.0716(7)
13.6689(10)
14.0514 (11)
65.498(2)
72.612(2)
86.536(2)
1508.9(2)
1
1.243
293(2)
0.074
594
b [A]
c [A]
R [deg]
β [deg]
γ [deg]
V [A3]
Z
F
T [K]
calcd [g cm-3
]
100(2)
0.236
1336
293(2)
0.111
952
293(2)
0.070
1184
100(2)
0.071
2224
μ [mm-1
F(000)
]
θ range for data collection [deg]
index ranges
1.76 to 26.44
-13 e h e 13
-27 e k e 27
-16 e l e 17
28 596
6635
0.0317
6635/0/397
2.13 to 24.10
-21 e h e 18
-18 e k e 17
-9 e l e 9
12 349
2090
0.0259
2090/0/168
1.51 to 23.29
-13 e h e 13
-16 e k e 16
-18 e l e 18
18 239
7653
0.0328
7653/0/657
1.55 to 20.86
-8 e h e 8
-23 e k e 23
-15 e l e 15
16 631
1.67 to 22.01
-9 e h e 9
-14 e k e 14
-14 e l e 14
18 707
0.90 to 24.59
-26 e h e 26
-19 e k e 20
-16 e l e 16
41 155
9131
0.0521
9131/0/758
reflns measd
indep reflns
Rint
data/restraints/params
3291
0.0242
3690
0.0218
3291/131/398a
3690/131/409a
final R values [I > 2θ(I)]:
R1
wR2
R values (all data):
0.0437
0.1052
0.0427
0.1140
0.0432
0.0978
0.0397
0.0920
0.0363
0.0916
0.0524
0.1361
R1
wR2
0.0524
0.1087
1.062
0.0496
0.1194
1.027
0.0589
0.1047
1.017
0.0496
0.0976
1.044
0.0412
0.0948
1.052
0.0613
0.1450
1.026
GOF on F2
a DELU restraints were applied to all thermal displacement parameters.
(phenyl o/m-C), 127.3 (C16, C21), 127.1 (phenyl p-C), 126.5
(phenyl o/m-C), 125.7 (phenyl p-C), 124.1 (C1, C8), 123.6 (C15,
C22), 120.5 (C18, C19), 120.4 (C4, C5), 83.7 (C9), 73.0 (C12).
ESMS: calcd for C42H28O [M-OH-], 531.21; found, 531.31.
Data for 31: 1H NMR (400 MHz, CDCl3): δ 7.90 (d, J = 7.6 Hz,
2H, H18, H19), 7.81 (d, J = 7.6 Hz, 2H, H4, H5), 7.46-7.39
(m, 2H, H17, H20), 7.35 (td, J = 7.5, 0.8 Hz, 2H, H3, H6),
7.29-7.21 (m, 4H, H15, H16, H21, H22), 7.17 (td, J = 7.4, 0.8 Hz,
2H, H2, H7), 7.07 (d, J = 7.5 Hz, 2H, H1, H8), 6.94 (t, J = 7.3
Hz, 1H, H32), 6.85 (t, J = 7.6 Hz, 2H, H31, H33), 6.81 (td, J =
7.5, 1.0 Hz, 1H, H27), 6.74 (td, J = 7.5, 1.1 Hz, 1H, H26), 6.72 (d,
J = 7.6 Hz, 2H, H30, H34), 6.48 (d, J = 7.6 Hz, 1H, H25), 6.46 (s,
1H, H13), 6.24 (d, J = 7.2 Hz, 1H, H28). 13C NMR (101 MHz,
CDCl3): δ 157.5, 155.5 (C10, C11), 153.5 (C24), 145.6 (C8a, C9a),
least-squares on F2 for all data using SHELXL-97.35 The
treatment of the hydrogen atoms varies from compound to
compound, depending on the data quality. All hydrogen atoms
in 9 and 14 were located in the difference Fourier map and
allowed to refine freely with isotropic thermal displacement
parameters. All other hydrogen atoms were added at calculated
positions and refined using a riding model. Their isotropic
temperature factors were fixed to 1.2 times (1.5 times for methyl
groups) the equivalent isotropic displacement parameters of the
carbon atom the H-atom is attached to. Anisotropic thermal
displacement parameters were used for all non-hydrogen atoms.
In 21 the solvent dichloromethane could not be located in the
unit cell. The Platon SQUEEZE procedure was used to com-
pensate for the electron density spread. In 15 the hydrogen
atoms of the water molecule could not be detected. The structure
of 31 was refined as a pseudo-orthorhombic twin. Refinement in
the other possible space group, Pbca, did not lead to a satisfactory
result. All structures are shown as Mercury36 representations.
Crystallographic data for the structures reported in this
paper have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publications nos. CCDC 752575
(9), 752577 (12), 752580 (13), 752579 (14), 752576 (15), 752585
(21), 752583 (25), 752578 (26), 752584 (27), 752581 (30), and
752582 (31).
144.8 (C14), 143.1 (C12a, C22a), 142.5 (C4a, C4b), 142.2 (C18a
C
,
18b), 138.2 (C13), 138.0 (C23), 134.2 (C29), 128.1 (C3, C6, C17,
C20), 128.0 (C2, C7), 127.9 (C16, C21, C31, C33), 127.3 (C32), 127.2
(C27), 126.7 (C30, C34), 125.5 (C26), 123.8 (C15, C22), 123.6 (C1,
C8), 122.8 (C25), 120.7 (C18, C19), 120.4 (C4, C5), 118.5 (C28),
64.6 (C12), 64.3 (C9). HRMS: calcd for C42H26 [M þ Hþ],
531.2113; found, 531.2120. Anal. Calcd for C42H26 0.5MeOH:
3
C, 93.37; H, 5.16. Found: C, 92.87; H, 5.11. A sample suitable for
an X-ray crystal structure determination was obtained by recrys-
tallization from ether/dichloromethane for both 30 and 31.
X-ray Crystallography. X-ray crystallographic data for 9,
12-15, 21, 25, 26, 27, 30, and 31 were collected using a Bruker
SMART APEX CCD area detector diffractometer and are
listed in Tables 1 and 2. A hemisphere of reciprocal space for
25 and a full sphere of reciprocal space for all the others were
scanned by phi-omega scans. Pseudoempirical absorption cor-
rection based on redundant reflections was performed by the
program SADABS.34 The structures were solved by direct
methods using SHELXS-9735 and refined by full matrix
Acknowledgment. We are grateful to Science Founda-
tion Ireland and University College Dublin for generous
financial support. L.A. (University of Hamburg) and
ꢀ
R.B. (Ecole Nationale Superieure de Chimie, Paris) thank
the Erasmus Programme for Exchange Fellowships.
Supporting Information Available: This material is available
free of charge via the Internet at http://pubs.acs.org.
(34) Sheldrick, G. M. SADABS; Bruker AXS Inc.: Madison, WI, 2001.
(35) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112–122.
(36) Mercury 1.4.2, available from http://www.ccdc.cam.ac.uk/mercury/.