Stereoselective preparation of spirane bridged, sandwiched bisarenes

Article abstract of DOI:10.1016/j.tet.2005.02.021

Preparation of α-oxo derivatives of spiro[4.4]nonane, spiro[4.5]decane and spiro[5.5]undecane derivatives is described. An efficient method for spiroannulation by Rh(I)-catalysed intramolecular hydroacylation provides α,α′-difunctionalised spiro[4.5]decan

Full text of DOI:10.1016/j.tet.2005.02.021

Tetrahedron 61 (2005) 4129–4140
Stereoselective preparation of spirane bridged,
sandwiched bisarenes
Marit Rolandsgard, Saad Baldawi, Doina Sirbu, Vidar Bjørnstad, Christian Rømming
*
and Kjell Undheim
Department of Chemistry, University of Oslo, N-0315 Oslo, Norway
Received 8 November 2004; revised 20 January 2005; accepted 3 February 2005
Abstract—Preparation of a-oxo derivatives of spiro[4.4]nonane, spiro[4.5]decane and spiro[5.5]undecane derivatives is described. An
efficient method for spiroannulation by Rh(I)-catalysed intramolecular hydroacylation provides a,a0-difunctionalised spiro[4.5]decanes. The
a,a0-dioxo groups have been converted into vinyl triflates for arylation by Pd-catalysed cross-coupling reactions under Stille, Negishi or
Suzuki conditions depending on relative reactivities. Stereoselective saturation of the conjugated aryl olefinic bonds by catalytic
hydrogenation over Pd–carbon provides methodology for stereoselective preparation of a-aryl- and a,a0-cis,cis-diaryl spiranes, the latter
with a sandwich like structure. Single crystal X-ray analyses have been used in the structural assignments.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
and this restriction is transferred to the substituents. The
rigidity in the spirane is controlled by the size of the two
rings forming the spirane. Small-ring spiranes are very stiff.
The larger ring systems are more flexible.
The rigid framework in small-ring spiranes constitutes a
potentially useful scaffold for attachment of configuration-
ally highly oriented coordinating functions as ligands for
metal complexation, or for stereochemically controlled
attachment of pharmacophoric groups useful in medicinal
chemistry. A spirane bridged sandwich like the bisarene A
and its conformer B in Scheme 1 are reminiscent of certain
ligands for metallocenes. In these spiranes the functional
substituents R are situated in the a,a0-positions to be close to
the spirocenter. Alternative sites are the b- or g-positions or
combinations thereof.
We have initiated studies with the ultimate aim of
constructing spirobridges between functional units.
Essential intermediates are oxospiranes. A rhodium(II)-
carbenoid C–H insertion reaction has been used for
spiroannulation to provide b,b0- and a,a0-dioxospiranes.
The ring size of the carbocyclic substrate could be varied,
but spiroannulation was limited to the addition of five-
membered carbocycles.1 In a method with a potentially
wider application, functionalised spiranes were constructed
using ruthenium(II)-catalysed ring-closing metathesis. The
products were a,a0-dioxospiranes or derivatives thereof.
The substrates were appropriately substituted five-, six- and
seven-membered cycloalkanes which were spiroannulated
by five-, six and seven-membered rings, respectively.2
Nucleophilic substitutions in spiranes in the most desirable
a-position are complicated by the neo-effect from the
spirocenter, and reactions involving carbonium inter-
mediates at the a-carbon are likely to result in skeletal
rearrangements. Addition of metal hydrides or organo-
metallics to an a,a0-dioxospirane gives diols which are
sensitive to ring-opening reactions, especially when the
carbon substituent is an arene.3,4
Scheme 1.
The two rings in the spirane are interconnected through a
common ring atom. The two rings have an orthogonal
relationship. Conformational freedom is highly restricted,
Keywords: a,a0-cis,cis-Diarylspiranes; Spirane bridges; Stereoselective
hydrogenation; Rh(I)-catalysed hydroacylation.
A method for carbylation in the a-oxo position has been
found by initial formation of enol triflate and a subsequent
*
Corresponding author. Tel.: C47 22 85 55 21; fax: C47 22 85 55 07;
e-mail: kjell.undheim@kjemi.uio.no
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.02.021

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M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
Pd-mediated cross-coupling reaction.5 Full stereoselectivity
in the generation of cis,cis-a,a0-diarylspiranes has been
achieved by way of catalytic hydrogenation of the
corresponding a,a0-dienospiranes as shown in Schemes 7
and 8.
were run in the absence of a solvent. In this procedure, the
aldehyde and 5% [Rh(COD)Cl]2 were heated together with
dppe at 110 8C for 8 d. The yield of decarbonylated material
was reduced to barely 2% whereas the spiroannulated
cyclopentanone 5 was obtained in a very high yield, 90%.
The spiranedione 6 was readily available by acid hydrolysis
of the acetal 5. The spirane 6 could also be prepared from
2-allyl-2-formylcyclohexanone by the rhodium(I)-catalysed
hydridoacylation. The relatively high volatility of the
aldehyde substrate, however, made this reaction less
attractive.
2. Results and discussion
Scheme 2 outlines the preparation of a,a0-dioxospirane
intermediates. The smallest member of the dioxospirane
family in this work was spiro[4.4]nonane-1,6-dione (3),
which was available by a simple alkylation of ethyl
2-oxocyclopentanecarboxylate, and provided a subsequent
acid hydrolysis product 2 which was cyclised under acid
catalysis (Scheme 1).6 For the higher homologue 6, a new
synthetic route was developed. From the literature, it is
known that rhodium-catalysed intramolecular hydro-
acylation of 4-alkenyls constitutes a useful method for the
preparation of cyclopentanones.7 The main steps in the
catalytic hydroacylation reaction are thought to be oxidative
insertion into the aldehyde C–H bond, a subsequent olefin
insertion to furnish a rhodacycle intermediate which on
reductive elimination regenerates the catalyst and produces
a cyclopentanone.8 The synthesis of ketones from alde-
hydes, however, is complicated by decarbonylation in the
acylmetal intermediate by a rearrangement whereby the
carbonyl group becomes coordinated to the metal as carbon
monoxide leading to a less reactive catalyst complex as well
as to decarbonylation.9 In the synthesis of spiro[4.5]decane-
1,6-dione derivatives by hydroacylation of 4-pentenals,
product analysis showed extensive decarbonylation. The
reactions were run in benzonitrile.10 In our initial work we
also used benzonitrile as solvent at 110 8C with an acetal of
2-allylcyclohexanone-2-carbaldehyde 4 (Scheme 2) as
substrate. A satisfactory catalyst system was 10%
Rh(COD)(dppe)Cl. Decarbonylation, however, was signifi-
cant. The desired product was obtained together with 25%
of decarbonylated material. With nitromethane as an
alternative solvent, there was an increase in the decarbonyl-
ation, up to 33%. We then discovered that the decarbonyl-
ation could largely be avoided when the hydroacylations
The spiro[5.5]undecan-1,7-dione series was available by an
initial Ru(II)-catalysed RCM reaction of the diene 7.2 The
product was the unsaturated spiranone 8. Saturation of the
carbon–carbon double bond over 10% Pd–C, and a
subsequent acid catalysed hydrolysis of the acetal function,
furnished the 1,7-dioxospirane 10.
Scheme 3 shows the preparation of triflate reactants for the
cross-coupling carbylation reactions. For triflation at the
a-carbon, either PhNTf2 or Tf2O was used. The milder
reagent PhNTf2 was generally the better.
With LiHMDS as base and PhNTf2 for triflation, the
monotriflate 11 was isolated in 80% yield, and the ditriflate
12 in 5% yield. A second triflation to form the correspond-
ing a,a0-ditriflate in the spirane series in general has been
difficult to effect. In the case of the spiro[4.4]nonane series,
however, the ditriflate 12 was finally obtained in excellent
yield (90%) when the triflation was run with Tf2O in DMAP
using the monotriflate 11 as substrate. The reaction was
slow. Monotriflation in the spiro[4.5]decane-1,6-dione
series proceeded well with LiHMDS as base. Only one
monotriflated product was seen. The product was the five-
membered ring triflate 13, yield 64%. The a-protons in the
five-membered ring ketone are more acidic than in the six-
membered ring ketone. Direct ditriflation from the a,a0-
diketone 6, however, gave only the ditriflate 14 in a very low
yield. As experienced in the spiro[4.4]nonane series,
ditriflation could be effected in a two-step operation albeit
Scheme 2.

M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
4131
Scheme 3.
in a low 13% yield of the ditriflate 14 using triflic anhydride
in pyridine. Apparently, a H-3 proton in the five-membered
ring is abstracted preferentially rather than an a-oxo proton
in the six-membered ring.
proceeded readily to provide the triflates 17 and 18 in ca.
80% yield.
Carbon–carbon bond forming reactions by Pd-catalysis are
shown in Scheme 4. A preliminary study of ortho-
substituted organometallic reactants showed that the cross-
coupling into the shielded a-position in spiranes was
sensitive to steric interactions from the o-substituent. A
In the spiro[5.5]undecan-1,7-dione series, the monotriflated
product 15 was isolated. Further triflation was difficult
to effect. Monotriflation of the acetals 5 and 8
Scheme 4.

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M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
Scheme 5.
2-methoxy group in the organometallic reactant provided a
reasonably good yield in the cross-coupling reaction. Hence
organometallic anisole derivatives were used for the
subsequent cross-coupling reactions. Thus, the Stille
coupling between 2-(tri-n-butylstannyl)anisole and the
monotriflate 11 proceeded readily to furnish the mono-
arylated product 19 in high yield. For a further carbylation
reaction, product 19 was triflated using Tf2O in DMAP.
Stille reaction conditions provided the product 21. This
approach allows for differential carbylation in the two a,a0-
positions in spiranes. In this case the same stannyl coupling
reagent was used, thereby providing the C2-symmetric
diarylated product 21. The successful preparation of the
bistriflate 12, allowed direct Pd-catalysed dicoupling. In this
case, however, Negishi coupling conditions with an
organozinc reactant gave a better yield, 75% (Scheme 5).
The cross-coupling under Stille conditions of the acetalised
triflate of spiro[4.5]undecane 17 was not satisfactory. We
therefore effected the coupling with the appropriate
benzeneboronic acid under Suzuki conditions with sodium
carbonate as base in aqueous DME. The cross-coupled
product 22 was isolated in high yield and was subsequently
hydrolysed to ketone 23 under acidic conditions. Triflation
of the ketone 23 was effected with lithiation at low
temperature and treatment with PhNTf2 to furnish the
triflate 24. Suzuki coupling conditions as above provided
the diarylated spirane 25. Dicoupling with the ditriflate 14
(Scheme 3) as substrate had previously failed to provide the
dianisole product 25.
In the spiro[5,5]undecane series, a two-step process was
used for introduction of the two arene groups (Scheme 6).
Scheme 6.

M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
4133
Scheme 7.
With the phospine P(2-furyl)3 for ligation of palladium, the
Stille conditions in NMP as solvent provided the arylated
spirane 26 from the keto triflate 15. Triflation in the
monoaryl spirane 26 was effected with triflic anhydride in
pyridine and furnished the triflate 27 in high yield. As stated
above, this two-step process allows for differential carbyl-
ation in the two spirane rings. In this case, a 2-thienyl group
was introduced under Suzuki conditions to provide the
mixed diarylated product 28 in good yield. The coupling of
the diene acetal 18 under Stille conditions proceeded more
readily than for the ene triflate 15.
the least favourable structure of the three geometrical
isomers. For steric reasons, on heterogenous hydrogenation
the less sterically shielded face of a spirane ring becomes
associated with the metal catalyst. A subsequent transfer of
hydrogen from the metal to the double bond forces the
substituent into a cis-position. Thus both the styrene double
bonds in structures 21 and 25 were saturated over 10% Pd–
charcoal (Scheme 7). The long reaction times may reflect
steric crowding, but the reaction was fully stereoselective in
that only one product was seen, viz. the cis,cis-isomers 30
and 33. The relative configuration assigned for the latter has
been ascertained by a single crystal X-ray analysis (vide
infra). The assignment of the relative configuration of the
former is based on the established configuration of its lower
phenyl analogue.5
In the target spirane structure A in Scheme 1, the
functionalized aryl rings have a cis,cis-relationship. In the
substrates from the cross-coupling reactions, the aryl groups
are hinged to an sp2-hybridised carbon and are thus coplanar
with the orthogonal spirane rings, respectively. In a
saturated spirane, the a,a0-substituents at sp3-hybridised
carbons can have a cis,cis-, a cis,trans-, or trans,trans-
relationship. A stereoselective reduction of the double
bonds for formation of the cis- or the cis,cis-isomer is
required. The cis,cis-configuration, however, leads to a
significant repulsive interaction, and is thermodynamically
The monoarylated substrates 22 and 29 in Scheme 8 reacted
under similar conditions to provide a single reduction
product. The spiro[5.5]undecane substrate 29 is a 1,3-diene.
Stereoselectivity in the reduction furnished a single product
which was found by a single crystal X-ray analysis to be the
cis-isomer 36. The double bond in the spiro[4.5]decane
substrate 22 was saturated under similar conditions. The
Scheme 8.

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M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
semihydrolysed product 32 were isolated in 76 and 20%
respectively, after 5 d at ambient temperature.
The relative stereochemistry of compounds 33 and 36 was
determined by single crystal X-ray analyses. The ORTEP
plots of the crystal structures are shown in Figures 1 and 2.
In the crystal structure the anisole units in structure 33 have
an antiparallel arrangement corresponding to conformer B
in Scheme 1.
3. Conclusion
In conclusion, we have described a method for the
preparation of spiro[4.4]nonane, spiro[4.5]decane and
spiro[5.5]undecane a-oxo derivatives. In particular, an
efficient method for Rh-catalysed intramolecular hydro-
acylation was developed for the preparation of a,a-
difunctionalised spiro[4.5]decanes. Substitutions in the
a-positions in the spiranes has been effected from the
corresponding ketones by way of vinyl triflates and
palladium catalysed cross-coupling reactions. In most
cases, ditriflation was best effected in a step-wise manner.
To cope with different reactivities of the vinyl triflate
substituents in the spiranes, Stille, Negishi and Suzuki
conditions were all employed. Catalytic hydrogenation over
Pd–carbon provides methodology for stereoselective
preparation of a-cis-aryl- and a,a0-cis,cis-diaryl spiranes,
the latter with a sandwich like structure.
Figure 1. The ORTEP plot of compound 33. Ellipsoids are shown at 50%
probability. For clarity only the hydrogen at stereogenic centers and at
double bonds are shown.
product has tentatively been assigned the cis-structure 34 by
analogy to the formation of the cis-isomer 36 and the cis,cis-
isomers 30 and 33. The ketone 35 was available after acid
hydrolysis of the acetal 34.
In spiro-bridged sandwich-like bisarene structures with
ligand properties towards a metal in the center, the aryl
group would carry substituents with coordinating properties.
The model substituent in the present work was the
o-methoxy group (Scheme 7). The methoxy group can
also be regarded as a methyl O-protected phenolic group.
Trimethylsilyl iodide was used to cleave the methyl aryl
ether 30 to furnish the diphenol sandwich structure 31
(Scheme 7). Slow cleavage required the use of a large
excess of the silyl iodide reagent. The diol 31 and the
4. Experimental
The 1H NMR spectra were recorded at 300 or 500 MHz and
the 13C NMR spectra at 75 or 125 MHz. Chemical shifts are
given in ppm relative to the solvent CDCl3. Coupling
constants J are given in Hz. Interpretation of the NMR
spectra was helped by COSY, DEPT HETCOR and COLOC
techniques. The mass spectra were recorded at 70 eV under
electron impact conditions (EI) and are presented as m/z (rel.
int.). IR spectra were measured on a Nicolet Magna 550
spectrometer using ATR (attenuated total reflectance).
THF, toluene and diethyl ether were dried over sodium.
Dichloromethane was distilled over calcium hydride.
Solvents were degassed by bubbling argon through.
Reactions under dry conditions were run under an argon
atmosphere.
4.1. X-ray crystallographic analysis for compounds 33
and 36
X-ray data were collected on a Siemens SMART CCD
diffractometer11 using graphite monochromated Mo Ka
˚
radiation (lZ0.71073 A). Data collection method: u-scan,
range 0.68, crystal to detector distance 5 cm. Data reduction
and cell determination were carried out with the SAINT and
XPREP programs.11 Absorption corrections were applied by
the use of the SADABS program.12 The structures were
determined and refined using the SHELXTL program
package.13 The non-hydrogen atoms were refined with
anisotropic thermal parameters; hydrogen atoms were
Figure 2. The ORTEP plot of compound 36. Ellipsoids are shown at 50%
probability. For clarity only the hydrogen at stereogenic centers and at
double bonds are shown.

M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
4135
located from difference Fourier maps and refined with
isotropic thermal parameters.
(300 MHz, CDCl3) d 1.20–1.74 (12H, m, CH2), 2.15–2.47
(4H, m, CH2), 3.79–3.96 (4H, m, H2, H3); 13C NMR
(75 MHz, CDCl3) d 20.6 (CH2) 21.1 (CH2), 23.2 (CH2),
27.2 (CH2), 31.8 (CH2), 32.7 (CH2), 33.3 (CH2), 40.4 (CH2),
56.0 (C6), 64.1 (C2) 64.0 (C3), 110.9 (C5), 213.2 (C7);
MS(EI): 224 (M, 26%), 179 (52), 99 (100), 86 (38).
Structural data have been deposited at the Cambridge
Crystallographic Data Centre deposition number CCDC
250768 for compound 33, and CCDC 250769 for compound
36.
4.1.6. Spiro[5.5]undecane-1,7-dione (10). A solution of the
1,4-dioxadispiro[4.0.5.4]pentadecan-7-one (9) (500 mg,
2.2 mmol) in CH2Cl2 (10 mL) and 5 M HCl (8 mL) was
stirred overnight at ambient temperature. The mixture was
extracted with diethyl ether (2!15 mL), washed with
water, with saturated NaHCO3 solution and brine. The
solvent was evaporated and the crude product purified by
flash chromatography using hexane/EtOAc 6:1; yield 0.38 g
(95%) of a white crystalline solid, mp 49–50 8C. (Found: C,
73.30; H 8.95. Calcd for C11H16O2: C, 73.09; H, 9.04%).
HRMS: M 180.1146. Calcd for C11H16O2: 180.1150. IR
(film) n cmK1 2900 (C–H), 1686 (C]O); 1H NMR
(300 MHz, CDCl3) d 1.21–1.75 (3H, m, CH2), 2.45–3.38
(1H, m, H2, H8); 13C NMR (75 MHz, CDCl3) d 21.2 (CH2),
21.6 (CH2), 27.7 (CH2), 36.2 (CH2), 40.8 (C2, C8), 64.5
(C6), 210.9 (C1, C7). MS (EI): 180 (M, 41%), 152 (57), 124
(70), 111 (61), 67 (63), 55 (95), 41 (100).
4.1.1. Crystal data for C24H30O2 (33). MZ350.48,
˚
˚
monoclinic, P21/n, aZ8.133(1) A, bZ25.511(1) A, cZ
3
˚
˚
9.848(1) A, bZ107.84(1)8, VZ1925.3(1) A , ZZ4, DxZ
1.209 Mg mK3, mZ0.075 mmK1, TZ105(2) K, measured
27,375 reflections in 2q range 5.4–61.08, RintZ0.032. 355
parameters refined against 5859 F2, RZ0.050 for IoO2s(Io)
and 0.063 for all data.
4.1.2. Crystal data for C17H22O (36). MZ242.35,
˚
˚
monoclinic, Pca21, aZ14.367(1) A, bZ12.610(1) A, cZ
3
K3
˚
˚
7.490(1) A, VZ1356.9(1) A , ZZ4, DxZ1.186 Mg m
,
mZ0.071 mmK1, TZ105(2) K, measured 28,782 reflec-
tions in 2q range 3.2–72.88, RintZ0.026. 251 parameters
refined against 6380 F2, RZ0.033 for IoO2q(Io) and 0.039
for all data.
4.1.3. 1,4-Dioxadispiro[4.0.4.4]tetradecan-7-one (5).
6-Allyl-1,4-dioxaspiro[4.5]decane-6-carbaldehyde2 (4)
(4.929 g, 23.5 mmol), (Rh(COD)Cl)2 (0.261 g, 0.59 mmol)
and dppe (0.468 g, 1.18 mmol) were heated together at
110 8C for 8 d when GLC showed the reaction to be
complete. Excess hexane was added to the reaction mixture
to precipitate the catalyst which was removed by filtration
and the filtrate evaporated. The residual material was
subjected to flash chromatography using 30% diethyl ether
in hexane. The product was a yellow oil; yield 3.641 g
(64%). (Found: C 68.51, H 8.67. Calcd for C12H18O3: C
68.54, H 8.63%); HRMS(EI): M 210.1260. Calcd for
C12H18O3: 210.1256. IR (film) n cmK1 2935 (m), 2884
4.1.7. Trifluoromethanesulfonic acid 6-trifluoro-
methanesulfonyloxyspiro[4.4]nona-1,6-diene-1-yl ester
(12).5 A solution of trifluoromethanesulfonic acid 6-oxo-
spiro[4.4]non-1-en-1-yl ester (11) (1.5 g, 5.2 mmol) and
DMAP (708 mg, 5.8 mmol) in dry dichloromethane
(100 mL) was stirred at room temperature for 24 h before
triflic anhydride (1.12 mL, 6.76 mmol) was added and the
mixture stirred at room temperature for 6 d to complete the
reaction (TLC). The solvent was evaporated and the product
purified by flash chromatography using hexane/EtOAc 5:1;
yield 90% of a colourless oil.5
1
(m), 1732 (s); H NMR (300 MHz, CDCl3) d 1.26–1.95
4.1.8. Trifluoromethanesulfonic acid 6-oxospiro[4.5]dec-
1-en-1-yl ester (13). A solution of HMDS (0.778 g,
4.82 mmol) and nBuLi (1.85 mL, 2.77 mmol) in THF
(5 mL) was added dropwise over 20 min to a solution of
spiro[4.5]decane-1,6-dione (6) (0.401 g, 2.40 mmol) and
PhNTf2 (0.987 g, 2.77 mmol) in THF (15 mL). at K78 8C.
The mixture was allowed to reach room temperature
overnight. The reaction was quenched by the addition of
saturated aqueous NaHCO3 (20 mL) and the mixture
extracted with diethyl ether (3!20 mL). The ether extracts
were dried (MgSO4), evaporated and the residual material
subjected to flash chromatography on slica gel using 20%
EtOAc in hexane. The product was a yellow oil; yield
0.460 g (64%). (Found: C, 44.14; H, 4.74. Calcd for
C11H12O4F3S1: C, 44.29; H, 4.39%). HRMS: M 299.0570.
Calcd for C11H12O4F3S1: 299.0565. IR (film) n cmK1 2944
(m), 2867 (w), 1710 (s), 1425 (s), 1209 (s), 1148 (s), 1017
(m); 1H NMR (300 MHz, CDCl3) d 1.66–1.74 (2H, m,
CH2), 1.83–1.88 (2H, m, CH2), 1.95–2.07 (3H, m, CH2),
2.13–2.18 (1H, m, H4), 2.32–2.38 (2H, m, H7) 2.39–2.45
(2H, m, H3), 5.78 (1H, t, JZ2.1 Hz, H2); 13C NMR
(125 MHz, CDCl3) d 20.5 (C4), 24.7 (C3), 25.2 (C10), 32.2
(C11), 34.4 (C12), 38.2 (C7), 60.2 (C5), 115.9 (C2), 117.4
(q, JZ319 Hz, CF3), 148.1 (C1), 209.2 (C6); m/z (CI): M
299 (100%), 281 (85), 254 (62), 165 (89), 149 (73), 121
(46).
(11H, m, CH2), 2.14–2.24 (3H, m, CH2), 3.79–3.89 (4H, m,
H2 and H3); 13C NMR (75 MHz, CDCl3) d 18.4 (CH2), 20.3
(CH2), 23.0 (CH2), 31.1 (CH2), 32.1 (CH2), 32.5 (CH2), 39.7
(C8), 55.2 (C5), 64.3 (C2 or C3), 65.0 (C3 or C2), 110.7
(C5), 218.9 (C7); m/z (EI): 210 (M, 32%), 165 (22), 99
(100), 86 (45).
4.1.4. Spiro[4,5]decane-1,6 dione (6).14 1,4-Dioxadispiro-
[4.0.4.4]tetradecan-7-one (5) (1.242 g, 5.91 was added to
3 M HCl (10 mL) in CH2Cl2 (15 mL)and conc. HCl (3 mL)
added. The mixture was stirred at room temperature
overnight before addition of aqueous saturated NaHCO3
(20 mL). Dichloromethane (5!20 mL) extraction furnished
the diketone; yield 1.130 g (91%).
4.1.5. 1,4-Dioxadispiro[4.0.5.4]pentadecan-7-one (9). 1,4-
Dioxadispiro[4.0.5.4]pentadec-9 en-7-one (8)2 (500 mg,
2.25 mmol) in ethanol (30 mL) was hydrogenated over
10% palladium on charcoal (500 mg) at 1 atm and ambient
temperature for 2 d. The catalyst was filtered off and the
solvent evaporated. The crude product was purified by flash
chromatography using hexane/EtOAc 20:1.The product
appeared as a yellow oil; yield 0.47 g, (93%). HRMS.
Found M 224.1409. Calcd for C13H20O3: 224.1412. IR
(film) n cmK1 2938 (C–H), 1702 (C]O); 1H NMR

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M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
4.1.9. Trifluoromethylsulfonic acid 6-trifluoromethyl-
sulfonyloxyspiro[4.5]deca-1,6-dien-1-yl ester (14). Triflic
acid anhydride (0.083 mL, 0.50 mmol) was added dropwise
over 5 min to a solution of trifluoromethanesulfonic acid
6-oxospiro[4.5]dec-1-en-1-yl ester (13) (0.100 g,
0.34 mmol) and pyridine (0.040 g, 0.50 mmol) in dichloro-
methane (8 mL) at K78 8C. The temperature was allowed to
reach room temperature overnight. The reaction mixture
was stirred for 3 d at room temperature before the solvents
were distilled off and the residual material subjected to flash
chromatography on silica gel using 10% EtOAc in hexane.
The product was an oily material; yield 0.019 g, 13%.
HRMS: M 297.0413. Calcd for C11H12O4F3S1: 297.0408;
IR (film) n cmK1 2927 (s), 2861 (m), 2358 (w), 1419 (m),
5.97 (1H, t, JZ3.0 Hz, H2, H8); 13C NMR (75 MHz,
CDCl3) d 17.7 (CH2), 24.0 (CH2), 31.7 (CH2), 43.6 (C6),
116.2 (q, CF3), 120.3 (C2, C8), 148.6 (C1, C7); MS (CI):
444 (M, 100%), 445 (24), 446 (16), 311 (9), 143 (20).
4.1.12. Trifluoromethanesulfonic acid 1,4-dioxa-
dispiro[4.0.4.4]tetradec-7-en-7-yl ester (17). A solution
of HMDS (5.129 g, 31.8 mmol) and nBuLi (12.5 mL,
19.1 mmol) in THF (20 mL) was added dropwise over
20 min to a solution of 1,4-dioxadispiro[4.0.4.4]tetradecan-
7-one (5) (3.337 g, 15.9 mmol) and PhNTf2 (6.812 g,
19.1 mmol) in THF (50 mL) at K78 8C. The temperature
was allowed to reach room temperature overnight and
saturated aqueous sodium hydrogen carbonate (70 mL)
added. The mixture was extracted with diethyl ether (3!
70 mL), the solution dried (MgSO4), filtered, the filtrate
evaporated and the residual material subjected to flash
chromatograpy on silica gel using 20% Et2O in hexane. The
product was a yellow oil; yield 4.673 g (84%). HRMS (EI):
M 342.0742. Calcd for C13H17O5F3S1: 342.0749. IR (film) n
cmK1 2939 (s), 2895 (s), 2865 (s), 1655 (m), 1421 (s), 1250
(s), 1211 (s); 1H NMR (500 MHz, CDCl3) d 1.23–1.32 (1H,
m, CH2), 1.45–1.49 (1H, m, CH2), 1.52–1.66 (5H, m, CH2),
1.74–1.77 (1H, m, H10), 1.99 (1H, dt, JZ13.3, 3.7 Hz,
CH2) 2.19–2.24 (2H, m, H9, H10) 2.42–2.45 (1H, m, H9),
3.82–3.87 (2H, m, H2, H3), 3.90–3.94 (1H, m, H2 or H3),
3.96–3.98 (1H, m, H3 or H2), 5.70 (1H, t, JZ2.6 Hz, H8);
13C NMR (125 MHz, CDCl3) d 21.2 (CH2), 23.2 (CH2),
26.1 (C9), 32.3 (CH2), 32, 5 (C10), 33.6 (CH2), 54.5 (C6),
64.4 (C3 or C2), 65.1 (C2 or C3), 112.0 (C8), 118.1 (C5),
118.4 (q, JZ318 Hz, CF3), 150.9 (C7); m/z (EI): 342 (M,
1.0%), 279 (16), 209 (41), 167 (33), 149 (100), 99 (43).
1
1207 (s), 1140 (m); H NMR (500 MHz, CDCl3) d 1.56–
1.63 (1H, m, H9), 1.75–1.80 (1H, m, H10), 1.80–1.84 (1H,
m, H9), 1.91–1.94 (1H, m, H10), 1.95–1.99 (1H, m, H4),
2.20–2.25 (2H, m, H8), 2.25–2.31 (1H, m, H4), 2.35–2.41
(1H, m, H3), 2.44–2.51 (1H, m, H3), 5.81 (1H, dd, JZ2.6,
2.5 Hz, H2), 5.91 (1H, dd, JZ4.3, 4.0 Hz, H7); 13C NMR
(125 MHz, CDCl3) d 18.7 (C9), 24.2 (C8), 25.7 (C3), 33.4
(C4), 34.0 (C10), 51.0 (C5), 117.2 (C2), 118.7 (q, JZ
319 Hz, CF3), 118.8 (q, JZ319 Hz, CF3), 120.1 (C7), 148.5
(C1), 148.5 (C6); m/z (CI, NH3): 448 (MCNHC4 , 100%),
391 (9), 281 (12), 213 (16), 147 (38).
4.1.10. Trifluoromethanesulfonic acid 7-oxospiro[5.5]-
undec-1-en-1-yl ester (15). LiHMDS (2.4 mmol) in THF
(10 mL) was added dropwise to a solution of spiro[5.5]-
undecane-1,7-dione (10) (370 mg, 2.05 mmol) and PhNTf2
(900 mg, 2.46 mmol) in THF (15 mL) under argon at
K78 8C. The mixture was allowed to reach ambient
temperature overnight. When GLC showed the reaction to
be complete, diethyl ether and water were added to the cold
reaction mixture, the layers separated and the aqueous layer
extracted with diethyl ether (2!). The combined ether
extract was shaken with aqueous Na2CO3, dried (MgSO4),
and the solution evaporated to dryness. The product was
isolated from the residual material after flash chromato-
graphy using hexane/EtOAc 10:1.The product was a yellow
oil; yield 222 mg (60%). HRMS: M 313.0713. Calcd for
C12H15O4SF3: 313.0721; IR (film) n cmK1 2926, 2855
(C–H), 1710 (C]O); 1H NMR (300 MHz, CDCl3) d 1.36–
2.31 (12H, CH2), 2.30–2.60 (2H, m, H8), 5.90 (1H, t, JZ
4.2 Hz, H2); 13C NMR (75 MHz, CDCl3) d 18.1 (CH2), 20.6
(CH2), 24.4 (CH2), 26.5 (CH2), 33.4 (CH2), 34.8 (CH2), 38.5
(C8), 54.5 (C6), 86.7 (CF3), 120.7 (C2), 149.8 (C1), 209.6
(C7); MS (EI): 313 (M, 55%), 268 (31), 179 (138), 163
(100), 135 (62), 179 (38).
4.1.13. Trifluoromethanesulfonic acid 1,4-dioxadispiro-
[4.0.5.4]pentadeca-7,9-dien-7-yl ester (18). 1 M LiHMDS
(600 mg, 3.76 mmol) in THF (15 mL) was added dropwise
to a solution of 1,4-dioxadispiro[4.0.5.4]pentadec-9-en-7-
one (8) and PhNTf2 (1.36 g, 3.8 mmol) in THF (10 mL)
under argon at K78 8C. The mixture was allowed to reach
ambient temperature overnight when GLC showed the
reaction to be complete. Diethyl ether and water were added
to the cold reaction mixture, the layers separated, the
aqueous layer extracted with diethyl ether (2!), the
combined ether solutions shaken with aqueous Na2CO3,
dried over MgSO4 and the solution evaporated to dryness.
The product was isolated from the residual material after
flash chromatography using hexane/EtOAc 10:1. The
product was a yellow oil; yield 1.10 g (80%). HRMS: M
354.0731. Calcd for C14H17O5F3S: 354.0749; IR (film) n
cmK1 2950 (C–H), 1664 (C]C); 1H NMR (300 MHz,
CDCl3) d 1.51–1.71 (6H, m, CH2), 2.15 (2H, m, H15), 2.36
(2H, m, H11), 3.79–4.04 (4H, m, H2, H3), 5.7 (1H, t, JZ
3.0 Hz, H9) 5.77 (1H, q, JZ3.0 Hz, H10), 5.95 (1H, d, JZ
6.0 Hz, H8); 13C NMR (75 MHz, CDCl3) d 20.1 (CH2), 23.5
(CH2), 30.5 (CH2), 34.0 (CH2), 35.2 (CH2), 45.0 (C6), 64.7
(C2 or C3), 65.9 (C3 or C2), 117.0 (q, CF3), 118.5 (C5),
120.5 (C8), 127.8 (C9), 130.2 (C10), 151.7 (C7). MS (EI):
354 (M, 32), 353 (100), 220 (28), 99 (46).
4.1.11. Trifluoromethanesulfonic acid 7-trifluoro-
methanesulfonyloxyspiro[5.5]undeca-1,7-dien-1-yl (16).
Neat triflic anhydride (0.9 mL, 5.6 mmol) was added with
a syringe to a solution of spiro[5.5]undecane-1,7-dione (10)
(0.5 mg, 2.8 mmol) and pyridine (442 mg, 5.6 mmol) in dry
dichloromethane (40 mL) at K78 8C under argon. The
reaction mixture was allowed to reach room temperature
and stirred at room temperature for 7 d. The solvent was
evaporated and the crude product was purified by flash
chromatography on silica gel using hexane/EtOAc 5:1;
yield 0.025 mg, 5%) of a colourless oil. IR (film) n cmK1
4.1.14. 6-(2-Methoxyphenyl)spiro[4.4]non-6-en-1-one
(19). Trifluoromethanesulfonic acid 6-oxospiro[4.4]non-1-
en-1-yl) (11) (284 mg, 1 mmol) and Pd(dba)2 (28.8 mg,
0.05 mmol) were dissolved in dry NMP (10 mL) and
1
1634 (C]C), 2880 (C–H). H NMR (300 MHz, CDCl3) d
1.56–1.91 (4H, m, CH2), 2.17–2.22 (2H, m, H3, H9), 5.95–

M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
4137
2-methoxyphenyltributyltin (436 mg, 1.1 mmol) added with
a syringe after 10 min. The solution was stirred at 80 8C
until the reaction was completed after 2 h (GLC). 1 M
aqueous KF solution (1 mL) was added and the mixture
stirred for 30 min, diluted with ethyl acetate and filtered.
The filtrate was washed with water (3!), dried (MgSO4)
and evaporated. The crude product was purified by flash
chromatography using hexane/EtOAc 4:1; yield 194 mg
(80%) of a pale yellow oil. (Found: C, 79.55; H, 7.62. Calcd
for C16H18O2: C, 79.33; H, 7.43%). HRMS: M 242.1306.
Calcd for C16H18O2: 242.1306. IR (film) n cmK1 2910,
2.4 (4H, m, CH2), 3.8 (3H, s, CH3), 6.15 (1H, t, JZ2.6 Hz,
H2, H7), 6.7–7.4 (4H, m, H-Ar); 13C NMR (50 MHz,
CDCl3) d 31.1 (CH2), 36.7 (CH2), 60.0 (CH3), 63.0 (C5),
111, 120 (C2, C7), 126, 127, 129, 132, 143 (C1, C6), 158
(Ph); MS(EI): m/z 332 (M, 100%), 211 (34), 185 (15), 149
(7), 147 (11), 121 (9), 91 (28), 84 (14).
4.1.16.2. Procedure (ii). nBuLi (1.6 M in 3.75 mL of
THF) was added dropwise to a solution of 2-bromoanisole
(1 mL, 5.7 mmol) in dry THF (40 mL) under argon at
K78 8C, and the mixture was stirred at room temperature
for 2 h. A solution of dried ZnBr2 (1.35 g, 6 mmol) in dry
THF (5 mL) was added. The mixture was stirred at K78 8C
for 1 h, and the temperature allowed slowly to reach room
temperature. Another solution of 1,6-bis(trifluoromethane-
sulfonyloxy)spiro[4.4]nona-1,6-diene (1.0 g, 2.4 mmol)
(12) in dry THF (10 mL) and Pd(PPh3)4 (138.6 mg,
0.12 mmol, 5 mol%) was prepared and stirred at room
temperature for 10 min before the solution was added to the
solution containing the organozinc reagent. The resultant
mixture was stirred at room temperature for 30 min, and at
50 8C for 90 min when GLC showed the reaction to be
complete. The reaction mixture was worked up as above;
yield 75%.
1
2220, 1710, 1450, 1250, 820, 720; H NMR (300 MHz): d
1.8 (4H, m, CH2), 2.0–2.2 (1H, m, CH2), 2.2–2.5 (4H, m,
CH2), 2.5–2.8 (1H, m, CH2), 3.75 (3H, s, CH3), 6.13 (1H, t,
JZ2.5 Hz, H7), 6.8–6.95 (2H, m, H-Ar), 7.15–7.35 (2H, m,
Ph); 13C NMR (75 MHz, CDCl3) d 19.8 (CH2), 30.0 (CH2),
34.5 (CH2), 35.6 (CH2), 37.7 (CH2), 54.0 (CH3), 63.7 (C5),
110, 120 (C7), 126, 128, 130, 133, 143, 156, 219 (C1);
MS(EI) m/z 242 (M, 100), 224 (33), 186 (99), 185 (34), 171
(50), 158 (15), 128 (14), 115 (13).
4.1.15. Trifluoromethanesulfonic acid 6-(2-methoxy-
phenyl)spiro[4.4]nona-1,6-dien-1-yl ester (20). DMAP
(346 mg, 2.48 mmol) was added to a solution of 6-(2-
methoxyphenyl)spiro[4.4]non-6-en-1-one (19) (345 mg,
1.42 mmol) in dry CH2Cl2 (15 mL) at room temperature
and the mixture stirred for 20 min. A solution of triflic
anhydride (600 mg, 2.13 mmol) in CH2Cl2 (1 mL) was
added dropwise and the mixture stirred at ambient
temperature for another 20 min to complete the reaction
(TLC). The solvent was evaporated and the product isolated
after flash chromatography of the residual material using
10% EtOAc in hexane; yield 480 mg (90%) of a pale yellow
oil. (Found: C, 54.73; H, 4.80. Calcd for C17F3H17O4S: C,
54.54; H, 4.54%). HRMS: M 374.0786. Calcd for
C17F3H17O4S: 374.0799. IR (film) n cmK1 3000, 2949,
2860, 1600, 1425, 1213; 1H NMR (300 MHz, CDCl3) d 1.9–
2.6 (8H, m, CH2), 3.8 (3H, s, CH3), 5.5 (1H, t, JZ2.1 Hz,
H2), 5.95 (1H, t, JZ2.4 Hz, H7), 6.9–7.25 (4H, m, H-Ar),
7.25 (1H, d, H-Ar); 13C NMR (50 MHz, CDCl3) d 21.0
(CH2), 29.6 (CH2), 33.9 (CH2), 37.0 (CH2), 55.0 (CH3), 63.0
(C5), 112 (C2), 114 (C7), 120, 126, 128, 130, 133, 142, 154,
158; MS (EI): m/z 374 (M, 100%), 241 (34), 213 (46), 171
(41), 133 (46), 131 (45), 121 (72), 115 (50), 69 (94), 55 (80).
4.1.17. 7-(2-Methoxyphenyl)-1,4-dioxadispiro[4.0.4.4]-
tetradec-7-ene (22). Pd(PPh3)4 (0.243 g, 2.15 mmol) was
added to a mixture of trifluoromethanesulfonic acid 1,4-
dioxadispiro[4.0.4.4]tetradec-7-en-7-yl ester (17) (1.469 g,
4.30 mmol), 2-anisoleboronic acid (0.950 g, 6.45 mmol),
aqueous 2 M Na2CO3 (10 mL) and DME (30 mL), and the
mixture heated at 100 8C for 3 h. Saturated sodium
hydrogen carbonate (30 mL) was added to the cold reaction
mixture, the mixture extracted with hexane (3!30 mL), and
the dried (MgSO4) hexane solution evaporated. The residual
material was subjected to flash chromatography on silica gel
using hexane; yield 0.928 g (72%) of a white crystalline
material; mp 65–66 8C. (Found C, 75.47; H, 7.85. Calcd for
C19H24O3: C, 75.97H, 8.00%). IR (film) n cmK1 3036 (w),
2928 (s), 2966 (w), 1495 (w); 1H NMR (300 MHz, CDCl3) d
1.35–1.54 (6H, m, CH2), 1.66–1.75 (1H, m, CH2), 1.85–1.94
(1H, m, H10), 2.01–2.10 (1H, m, CH2), 2.23–2.51 (3H, m,
H9 and H10), 3.41 (1H, m, H2 or H3), 3.68 (1H, q, JZ
7.3 Hz, H2 or H3), 3.92 (2H, m, H3 or H2), 3.74 (3H, s,
CH3), 5.68 (1H, t, JZ2.4 Hz, H8), 6.84 (2H, m, H-Ar), 7.04
(1H, dd, JZ7.3, 1.6 Hz, H-Ar), 7.16 (1H, m, H-Ar); 13C
NMR (75 MHz, CDCl3) d 22.4 (CH2), 23.4 (CH2), 30.5
(C9), 31.48 (CH2), 34.3 (C10), 35.5 (CH2), 55.2 (CH3), 59.9
(C6), 63.5 (C2 or C3), 64.1 (C3 or C2), 110.4 (C-Ar), 113.2
(C5), 119.3 (C-Ar), 127.3 (C-Ar), 130.3 (C-Ar), 131.4 (C-
Ar), 133.22 (C8), 144.4 (C7), 156.9 (C-Ar); m/z (EI): 300
(M, 100%), 238 (29), 212 (95), 185 (42), 99 (37).
4.1.16. 1,6-Bis(2-methoxyphenyl)spiro[4.4]nona-1,6-
diene (21).
4.1.16.1. Procedure (i). Trifluoromethanesulfonic acid
6-(2-methoxyphenyl)spiro[4.4]nona-1,6-dien-1-yl ester
(20) (374 mg, 1 mmol) and Pd(dba)2 (28.8 mg,
0.05 mmol) were dissolved in dry NMP (15 mL).
2-Methoxyphenyltributyltin (436 mg, 1.1 mmol) was added
with a syringe after 10 min. The solution was stirred at
80 8C overnight. A solution of aqueous KF (1 M, 1.5 mL)
was added and the mixture stirred for 30 min. Dilution with
ethyl acetate, filtration, shaking the filtrate with water (3!),
drying (MgSO4) and distilling off the solvents left an oily
residue. Pure product was isolated after flash chromato-
graphy on silica gel using hexane/EtOAc 10:1; yield 55% of
a pale yellow oil. (Found: C, 83.32; H, 7.20. Calcd for
C23H24O2: C, 83.13; H, 7.22%). HRMS: M 332.1766. Calcd
for C23H24O2: 332.1776. IR (film) n cmK1 3050, 3030,
2950, 2843, 2450, 1600; 1H NMR (300 MHz, CDCl3) d 1.9–
4.1.18. 1-(2-Methoxyphenyl)spiro[4.5]dec-1-en-6-one
(23). A solution of 7-(2-methoxyphenyl)-1,4-dioxadispiro-
[4.0.4.4]tetradec-7-ene (22) (0.687 g, 2.29 mmol, 1 equiv),
3 M HCl (6 mL) in CH2Cl2 (7 mL) was stirred at room
temperature for 4 h. Saturated aqueous sodium bicarbonate
(10 mL) was added and the mixture extracted with
dichloromethane (4!10 mL). Evaporation of the dried
(MgSO4) extracts provided a white crystalline material;
yield 0.551 g (94%), mp 60–62 8C. HRMS(EI): M 256.1462.
Calcd for C17H20O2: 256.1463; IR (film) n cmK1 2937 (s),

4138
M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
2862 (s), 1741 (s), 1698 (s); 1H NMR (300 MHz, CDCl3) d
1.47–1.67 (4H, m, CH2), 1.81–1.95 (3H, m, CH2), 2.18–2.23
(1H, m, CH2), 2.31–2.37 (2H, m, H3), 2.39–2.46 (2H, m,
CH2), 3.62 (3H, s, CH3), 6.10 (1H, dd, JZ2.8, 2.3 Hz, H2),
6.75–6.84 (2H, m, H-Ar), 7.10–7.23 (2H, m, H-Ar); 13C
NMR (125 MHz, CDCl3) d 22.0 (CH2), 25.2 (CH2), 30.2
(C3), 36.7 (CH2), 39.0 (CH2), 39.2 (CH2), 54.8 (CH3), 64.3
(C-Ar), 111.0 (C-Ar), 120.5 (C-Ar), 125.8 (C-Ar), 128.3
(C-Ar), 130.7 C-Ar), 133.1 (C2), 143.7 (C1), 156.3 (C-Ar),
211.0 (C6); m/z (EI): 256 (M, 100%), 238 (48), 228 (77),
199 (86), 186 (58), 185 (95).
(1H, d, JZ8.1 Hz, H-Ar), 6.89–6.93 (2H, m, H-Ar), 7.06
(1H, dd, JZ7.6, 1.5 Hz, H-Ar), 7.05–7.15 (1H, m, H-Ar),
7.14–7.22 (1H, m, H-Ar), 7.71 (1H, dd, JZ7.7, 1.6 Hz,
H-Ar); 13C NMR (125 MHz, CDCl3) d 20.2 (CH2), 25.8
(C7), 31.3 (C2), 36.6 (CH2), 39.8 (CH2), 55.3 (CH3), 55.4
(C5 and CH3), 110.6 (C-Ar), 111.1 (CH), 119.2 (C-Ar),
119.9 (CH), 127.1 (CH), 127.3 (C1 or C6), 127.3 (CH),
127.7 (CH), 129.8 (C-Ar), 130.8 (C-Ar), 131.9 (C6 or C1),
134.0 (C-Ar), 139.4 (C-Ar), 142.3 (C-Ar), 157.5 (C-Ar),
157.8 (C-Ar); m/z (EI): 346 (M, 100%), 318 (12), 225 (18),
199 (34), 160 (14), 91 (9).
4.1.21. 7-Phenylspiro[5,5]undec-7-en-1-one (26).
Pd(dba)3$CHCl3 (13 mg, 0.03 mmol) was added to a
solution of trifluoromethanesulfonic acid 7-oxospiro[5.5]-
undec-1-yl ester (15) (130 mg, 0.42 mmol), tri(2-
furyl)phosphine (12 mg, 0.05 mmol) and LiCl (35.2 mg,
0.83 mmol) in dry NMP (7 mL). The mixture was stirred for
10 min at room temperature before phenyltributylstannane
(1.6 mL, 0.5 mmol) was added with a syringe. The solution
was stirred at 80 8C for 16 h. 1 M aqueous KF (7 mL) was
added over 30 min to the cold reaction mixture which was
diluted with ethyl acetate and filtered. The filtrate was
washed with water (10 mL), dried (MgSO4) and evaporated.
The crude product was purified by flash chromatography on
silica gel using hexane/EtOAc 10:1. The product was a
colorless oil; yield 0.08 g (60%). HRMS: M 240.1510.
Calcd for C17H20O: 240.1514; IR (film) n cmK1 2938, 2862
4.1.19. Trifluoromethanesulfonic acid 1-(2-methoxy-
phenyl)spiro[4.5]deca-1,6-dien-6-yl ester (24). A solution
of HMDS (1.009 g, 6.25 mmol) and nBuLi (1.45 mL,
2.03 mmol) in THF (2.0 mL) was added dropwise over
5 min to a solution of 1-(2-methoxyphenyl)spiro[4.5]dec-1-
en-6-one (23) (0.400 g, 1.56 mmol) and PhNTf2 (0.726 g,
2.03 mmol) in THF (20 mL) at K78 8C. The reaction
mixture was allowed to reach room temperature overnight.
Saturated aqueous NaHCO3 solution (30 mL) was added
and the mixture extracted with diethyl ether (3!30 mL).
The dried extracts were evaporated and the residual material
subjected to flash chromatography on silica gel using 10%
EtOAc in hexane. The product was a colourless oil; yield
0.438 g (72%). HRMS (EI): M 388.0948. Calcd for
C18H19F3O4S1: 388.0947; IR (film) n cmK1 2936 (m),
2867 (w), 1402 (m), 1248 (m), 1209 (s), 1140 (m), 1032
(m); 1H NMR (500 MHz, CDCl3) d 1.40–1.53 (2H, m, H9),
1.67–1.71 (1H, m, H10), 1.88–1.93 (1H, m, H10), 1.96–2.06
(2H, m, H4 and H8), 2.10–2.17 (1H, m, H8), 2.33–2.38 (1H,
m, H4), 2.41–2.47 (1H, m, H3), 2.53–2.60 (1H, m, H3), 3.74
(3H, s, CH3), 5.71 (1H, dd, JZ4.9, 3.5 Hz, H7), 6.00 (1H,
dd, JZ2.5, 2.4 Hz, H2), 6.87 (2H, m, H-Ar), 7.13 (1H, dd,
JZ7.5, 1.6 Hz, H-Ar), 7.21 (1H, m, H-Ar); 13C NMR
(125 MHz, CDCl3) d 19.3 (CH2), 24.5 (CH2), 30.8 (C3),
35.9 (C8), 37.6 (C4), 55.1 (CH3), 55.3 (C5), 110.8 (C-Ar),
115.4 (C7), 118.7 (q, JZ318 Hz, CF3), 119.9 (C-Ar), 126.0
(C-Ar), 128.3 (C-Ar), 123.0 (C-Ar), 134.4 (C2), 140.8 (C1),
153.7 (C6), 157.5 (C-Ar); m/z (EI): 388 (M, 100%), 238
(25), 207 (100), 111 (16), 121 (41).
1
(C–H), 3028 (C–H, Ar), 1700 (C]O), 1600 (C]C); H
NMR (300 MHz, CDCl3) d 1.23–1.66 (10H, m, CH2), 1.80–
1.87 (2H, m, CH2), 2.20–2.61 (2H, m, CH2), 5.94 (1H, t, JZ
6.0 Hz, H8), 7.08–7.22 (5H, m, H-Ar); 13CNMR (75 MHz,
CDCl3) d 18.1 (CH2), 20.5 (CH2). 25.6 (CH2), 26.1 (CH2),
34.4 (CH2), 37.6 (CH2), 38.5 (C7), 54.1 (C6), 126.2, 127.8,
128.5, 130.5, 141.1, 142.7, 208.7 (C1); MS (EI): 240 (M,
100%), 211 (77), 169 (31), 155 (31), 141 (38), 91 (27), 77
(15).
4.1.22. Trifluoromethanesulfonic acid 7-phenylspiro-
[5.5]undeca-1,7-dien-1-yl ester (27). Neat triflic anhydride
(110 mg, 0.39 mmol) was added with a syringe to a solution
of 7-phenylspiro[5,5]undec-7-en-1-one (26) (63 mg,
0.262 mmol) and pyridine (30.8 mg, 0.39 mmol) in dry
CH2Cl2 (6 mL) at K78 8C under argon. The reaction
mixture was allowed to reach ambient temperature over
24 h. The product was purified by flash chromatography on
silica gel using hexane/EtOAc 10:1. The product was a
yellow oil; yield 131 mg (90%). (Found: C 57.74; H, 5.65.
Calcd for C18H19O3F3S: C, 57.36; H, 5.87%). IR (film) n
cmK1 2910 (C–H), 3020 (C–H Ar), 1672 (C]C); 1H NMR
(300 MHz, CDCl3) d 1.3–2.2 (12H, m, CH2), 5.80 (1H, dd,
JZ3.0, 2.7 Hz, H8), 7.0–7.3 (H-Ar); 13C NMR (75 MHz,
CDCl3) d 16.9 (CH2), 17.3 (CH2), 23.4 (CH2), 24.4 (CH2),
31.5 (CH2), 32.8 (CH2), 42.0 (C6), 117.1 (H2), 116.9 (q,
CF3), 125.7, 126.7, 128.1, 139.7, 130.7, 140.9 (C7), 151.9
(C1); MS (EI): 372 (M, 27%), 222 (29), 130 (100), 117 (39),
91 (9).
4.1.20. 1,6-Bis-(2-methoxyphenyl)spiro[4.5]deca-1,6-
diene (25). Pd(PPh3)4 (0.072 g, 2.15 mmol) was added to
a solution of trifluoromethanesulfonic acid 1-(2-methoxy-
phenyl)spiro[4.5]deca-1,6-dien-6-yl ester (24) (0.372 g,
0.95 mmol), 2-anisoleboronic acid (0.216 g, 1.43 mmol)
and 2 M Na2CO3 (3 mL) in DME (9 mL) and the reaction
mixture heated at 100 8C for 4 h. Saturated aqueous
NaHCO3 (15 mL) was added to the cold reaction mixture
which was extracted with hexane (3!15 mL). The dried
(MgSO4) hexane extracts were evaporated and the residual
material subjected to flash chromatography on silica gel
using 30% CH2Cl2 in hexane. The product was a white
crystalline material; yield 0.201 g (61%), mp 86–89 8C.
HRMS (EI): M 346.1929. Calcd for C24H26O2 346.1933; IR
(film) n cmK1 2994 (w), 2930 (s), 2832 (s), 1595 (m), 1490
(s), 1462 (s), 1433 (s), 1244 (s), 1028 (m); 1H NMR
(500 MHz, CDCl3) d 1.45–1.51 (1H, m, CH2), 1.53–1.64
(3H, m, CH2), 1.73–1.79 (1H, m, CH2), 2.06–2.20 (4H, m,
CH2), 2.30–2.35 (1H, m, CH2), 3.69 (3H, s, CH3), 3.76 (3H,
s, CH3), 5.58 (1H, dd, JZ3.1, 3.0 Hz, H7), 6.11 (1H, dd, JZ
2.6, 2.5 Hz, H2), 6.7 (1H, dd, JZ7.6, 7.1 Hz, H-Ar), 6.81
4.1.23. 2-(7-Phenylspiro[5.5]undeca-1,7-dien-1-yl)thio-
phene (28). Pd(PPh3)4 (94 mg, 0.089 mmol) was added to
a solution of trifluoromethanesulfonic acid 7-phenyl-
spiro[5.5]undeca-1,7-dien-1-yl ester (27) (300 mg,
0.81 mmol), and 2-thiopheneboronic acid (207 mg,

M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
4139
1.61 mmol) in 1:3 2 M Na2CO3/DME (10 mL). The reaction
mixture was heated at 100 8C overnight. Ethyl acetate and
water were added. The aqueous phase was collected,
extracted with EtOAc, the combined organic extracts
washed with dilute aqueous sodium bicarbonate, brine,
and dried (MgSO4) before the solvent was distilled off.
Flash chromatography of the residual material using
hexane/EtOAc 20:1 gave the product as a colourless oil;
yield 174 mg (70%). HRMS: M 306.1430. Calcd for
C21H22S: 306.1442; IR (film) n cmK1 1618 (C]C),
(C-Ar), 125 (C-Ar), 128 (C-Ar), 136 (C-Ar), 156 (C-Ar);
MS(EI): m/z 336 (M, 100%), 202 (7), 187 (25), 174 (36),
173 (24), 134 (15), 121 (24), 91 (25), 77 (6).
4.1.26. cis,cis-1,6-Bis(2-hydroxyphenyl)spiro[4.4]nonane
(31). A flask containing a solution of cis,cis-1,6-bis(2-
methoxyphenyl)spiro[4.4]nonane (30) (336 mg, 1 mmol) in
dry dichloromethane (10 mL) under argon was protected
from light by covering with aluminium foil. TMSI
(2 equiv!5) was added at intervals and the mixture stirred
at room temperature. TLC monitoring showed that the
starting material was consumed after 5 d when the reaction
was stopped. Two new major products had been formed
after 5 d. The reaction mixture was evaporated to dryness
and the residual material subjected to flash chromatography
on silica gel using hexane/EtOAc, 12:1. The major product
was the diol 31; yield 60%. The minor product was the
monomethoxy intermediate cis/cis-1-(2-methoxyphenyl)-6-
(2-hydroxyphenyl)spiro[4.4]nonane (32); yield: 20%.
1
2824–2966 (C–H), 3072 (C–H Ar); H NMR (300 MHz,
CDCl3) d 1.27–1.74 (8H, m, CH2), 2.03–2.3 (4H, m, CH2),
6.01 (1H, t, JZ4.0 Hz, H8), 6.28 (1H, t, JZ3.0 Hz, H2),
6.87–6.90 (1H, m, H-Ar), 7.03 (1H, t, JZ3.0 Hz, H-Ar),
7.16–7.33 (6H, m, CH-Ar); 13C NMR (75 MHz, CDCl3) d
14.2 (CH2), 18.2 (CH2), 26.1 (CH2), 26.2 (CH2), 34.7 (CH2),
34.9 (CH2), 42.7 (CH2), 123.0, 124.2, 126.3, 126.9, 127.6,
128.8, 129.3, 130.6, 138.3, 143.1, 144.8, 146.3. MS (EI):
306 (M, 24%), 302 (16), 208 (100), 212 (29), 176 (12), 91
(38).
Product 31 was a white crystalline material, mp 178–180 8C
(CHCl3). HRMS: M 308.1768. Calcd for C21H24O2:
4.1.24. 7-Phenyl-1,4-dioxadispiro[4.0.5.4]pentadeca-7,9-
diene (29). Pd(dba)2 (130 mg, 0.12 mmol) was added to a
solution of trifluoromethanesulfonic acid 1,4-dioxadispiro-
[4.0.5.4]pentadeca-7,9-dien-7-yl ester (18) (860 mg,
2.43 mmol) in dry N-methylpyrrolidin-2-one (NMP,
20 mL) and the mixture stirred at room temperature for
4 h. 1 M aqueous KF solution (9 mL) was added dropwise
over 30 min, the mixture diluted with ethyl acetate and
filtered. The filtrate was washed with water (2!), dried
(MgSO4) and evaporated. The crude product was purified by
flash chromatography on silica gel using hexane/EtOAc
10:1; yield 0.64 g (75%) of a colorless oil. HRMS: M
282.1623. Calcd for C19H22O2: 282.1620. IR (film) n cmK1
1653 (C]C), 2950 (C–H), 3451 (C–H, Ar); 1H NMR
(300 MHz, CDCl3) d 1.19–1.68 (8H, m, CH2), 2.72–2.73
(2H, m, H12), 3.22–3.83 (4H, m, H2, H3), 5.71–5.78 (2H,
m, H9, H10), 5.89–5.92 (1H, m, H8), 7.11–7.25 (5H, m,
H-Ar); 13C NMR (75 MHz, CDCl3) d 19.7 (CH2), 22.3
(CH2), 29.6 (CH2), 31.1 (CH2), 33.1 (C11), 44.1 (C6), 62.3
(C2), 63.8 (C3), 112.6 (C5), 123.2 (C8), 124.2, 124.7, 125.5,
126.4, 128.6, 143.1, 143.8 (C7); MS (EI): 282 (M, 45%),
281 (44), 220 (83), 167 (79),165 (55), 128 (37), 99 (56), 73
(100).
1
308.1776. IR (film) n cmK1 3480 (br.), 2958, 1470. H
NMR (200 MHz, CDCl3) d 1.70 (1H, m, CH2), 2.03 (4H, m,
CH2), 2.15 (1H, m, CH2), 3.11 (1H, d, JZ8 Hz, H1, H6),
3.28 (1H, s, OH), 6.4–7.2 (4H, m, H-Ar);. 13C NMR
(75 MHz, CDCl3) d 22.3 (CH2), 34.2 (CH2), 40.4 (CH2),
43.8 (C1, C6), 61.8 (C5), 117 (C-Ar), 122 (C-Ar), 127
(C-Ar), 128 (C-Ar), 135 (C-Ar), 153 (C-Ar); MS(EI): m/z
308 (M,100%), 173 (37), 160 (43), 159 (44), 149 (24), 145
(25), 133 (25), 120 (25), 107 (57), 91 (29).
The second product was cis,cis-1-(2-methoxyphenyl)-6-(2-
hydroxyphenyl)spiro[4.4]nonane (32).
4.1.27.
cis,cis-1-(2-methoxyphenyl)-6-(2-hydroxy-
phenyl)spiro[4.4]nonane (32). The title compound was
obtained as a pale yellow crystalline material, mp 154 8C
(CHCl3). (Found: C, 82.20; H, 8.15. Calcd for C22H26O2: C,
81.98; H, 8.07%). HRMS: M 322.1941. Calcd for
C22H26O2: 322.1932. IR (film) n cmK1 3480 (br.), 3050,
1
2945, 2840, 1470. H NMR (300 MHz) d 1.5–1.7 (2H, m,
CH2), 1.8–2.1 (8H, m, CH2), 2.1–2.2 (2H, m, CH2), 3.1–3.3
(1H, m, H1), 3.30 (3H, s, CH3), 3.40 (1H, s, OH), 3.54 (1H,
d, JZ7.5 Hz, H6), 6.3–7.2 (8H, m, H-Ar); 13C NMR
(75 MHz, CDCl3) d 22.0 (CH2), 34.0 (CH2), 40.4 (CH2),
40.7 (CH2), 43.4 (C1), 44.0 (C6), 54.6 (CH3), 61.1 (C5), 110
(C-Ar), 116 (C-Ar), 120 (C-Ar), 121 (C-Ar), 126.1 (C-Ar),
126.5 (C-Ar), 127.5 (C-Ar), 128.0 (C-Ar), 134.5 (C-Ar),
136.0 (C-Ar), 152.5 (C-Ar), 156.5 (C-Ar); MS(EI): m/z 322
(M, 100%), 187 (17), 174 (28), 173 (34), 159 (26), 145 (17),
134 (29), 121 (43), 107 (62), 91 (70).
4.1.25. cis,cis-1,6-Bis(2-methoxyphenyl)spiro[4.4]nonane
(30). A solution of 1,6-bis-(2-methoxyphenyl)-spiro[4.4]-
nona-1,6-diene (21) (332 mg, 1 mmol) in ethanol (20 mL)
was hydrogenated over 10% palladium on charcoal
(100 mg, 0.1 mmol) at 4 atm in a Parr apparatus at room
temperature for 3 d. The catalyst was removed by filtration
through Celite. The filtrate was evaporated and the residual
product purified by flash chromatography on silica gel using
hexane/EtOAc, 12:1. Recrystallisation of the product from
diethyl ether and ethanol yielded 302 mg (90%) of a white
crystalline material, mp 131 8C. (Found: C, 82.66; H, 8.54.
Calcd for C23H28O2: C, 82.40; H, 8.33%). HRMS: M
336.2083. Calcd for C23H28O2: 336.2089. IR (film) n cmK1
3000, 2950, 2450, 1600, 1500, 1250; 1H NMR (200 MHz) d
1.7–2.2 (6H!2, m, CH2), 3.40 (3H!2, s, CH3), 3.55 (1H!
2, d, JZ7.2 Hz, H1, H6), 6.2–7.1 (4H!2, m, H-Ar); 13C
NMR (75 MHz, CDCl3) d 22.4 (CH2), 34.8 (CH2), 41.6
(CH2), 43.8 (CH2), 54.9 (CH3), 60.7 (C-5), 109 (C-Ar), 119
4.1.28. cis,cis-1,6-Bis(2-methoxyphenyl)spiro[4.5]decane
(33). 10% Pd–C (0.204 g) was added to a solution of 1,6-
bis(2-methoxyphenyl)spiro[4.5]deca-1,6-diene
(25)
(0.139 g, 0.40 mmol) in ethanol (25 mL) and the mixture
stirred under hydrogen (1 atm) for 9 h. The catalyst was
filtered off and the product isolated after flash chromato-
graphy on silica gel using 3% Et2O in hexane. The product
was a white crystalline material; yield 0.100 g (73%), mp
97–100 8C (MeOH). HRMS: M 350.2253. Calcd for
C24H30O2: 350.2246. IR (film) n cmK1 3060 (w), 2928

4140
M. Rolandsgard et al. / Tetrahedron 61 (2005) 4129–4140
(s), 2859 (s), 2836 (m); 1H NMR (500 MHz, CDCl3) d 1.32–
1.36 (1H, m, CH2), 1.41–1.48 (2H, m, CH2), 1.53–1.56 (1H,
m, CH2), 1.63–1.71 (3H, m, CH2), 1.74–1.77 (1H, m, CH2),
1.84–1.89 (2H, m, CH2), 1.94–1.97 (1H, m, CH2), 2.01–2.09
(1H, m, CH2), 2.22–2.29 (2H, m, CH2), 3.30 (1H, dd, JZ
4.3, 4.0 Hz, H6 or H1), 3.36 (3H, s, C17 CH3), 3.38 (3H, s,
CH3), 3.56 (1H, s, H1 or H6), 6.29 (1H, d, JZ8.1 Hz, CH),
6.37 (1H, d, JZ8.11 Hz, CH), 6.62–6.66 (2H, m, CH),
6.85–6.92 (2H, m, CH), 6.99 (1H, s, CH), 7.35 (1H, s, CH);
13C NMR (75 MHz, CDCl3) d 21.0 (CH2), 22.7 (CH2), 22.9
(CH2), 29.8 (CH2), 33.4 (CH2), 35.4 (CH2), 38.5 (CH2), 38.6
(C6 or C1), 51.4 (C5), 54.6, 55.0, 108.8 (CH), 109.0 (CH),
118.6 (CH), 119.5 (CH), 125.1 (CH), 125.4 (CH), 128.8 (CH),
123.0 (CH), 134.0 (C), 134.6 (C), 156.0 (C), 156.5 (C); m/z
(EI): 350 (M, 87%), 188 (28), 147 (40), 121 (100), 91 (67).
156.5 (C-Ar), 214.5 (C6); m/z (EI): 258 (M, 40%), 240 (22),
148 (100), 111 (48), 91 (16).
4.1.31. cis-7-Phenylspiro[5,5]undecan-1-one (36). A
solution of 7-phenyl-1,4-dioxadispiro[4.0.5.4]pentadeca-
7,9-diene (29) (220 mg, 0.78 mmol) in ethanol (30 mL)
was hydrogenated over 10% palladium on charcoal
(440 mg) at 1 atm and ambient temperature for 3 d. The
catalyst was filtered off through Celite and the solvent
evaporated. The crude product was purified by flash
chromatography using hexane/EtOAc 20:1. The product
was a white solid with mp 88 8C; yield 160 mg, (75%).
HRMS: M 242.1664. Calcd for C17H22O: 242.1670. IR
(film) n cmK1: 1702 (C]O), 2900 (C–H), 3030 (C–H Ar);
1H NMR (300 MHz, CDCl3) d 1.31–1.80 (12H, m, CH2),
2.00–2.40 (4H, m, CH2), 2.60–2.70 (1H, m, H7), 7.1–7.3
(5H, m, H-Ar); 13C NMR (75 MHz, CDCl3) d 20.0 (CH2),
21.1 (CH2), 25.9 (CH2), 26.4 (CH2), 29.6 (CH2), 36.8 (CH2),
38.8 (CH2), 40.1 (CH2), 52.4 (C6), 53.9 (C7), 127.6 (C-Ar),
130.4 (C-Ar), 143.6 (C-Ar), 162.3 (C-Ar), 214.5 (c1); MS
(EI): 242 (M, 100%), 129 (51), 111 (65), 98 (50), 91 (60).
4.1.29. 7-(2-Methoxyphenyl)-1,4-dioxadispiro[4.0.4.4]-
tetradecane (34). 5% Pd–C (0.212 g) was added to a
solution of 7-(2-methoxyphenyl)-1,4-dioxadispiro[4.0.4.4]-
tetradec-7-ene (22) (0.104 g, 0.35 mmol) in EtOH (20 mL)
and the mixture stirred under hydrogen (1 atm) at room
temperature for 18 h. The catalyst was filtered off through
Celite, the filtrate evaporated and the residual product
purified by flash chromatography on silica gel using 5%
EtOAc in hexane. The product was a white solid; yield
0.074 g (72%), mp 93–95 8C (MeOH). (Found: C, 75.25; H,
8.95. Calcd for C19H26O3: C, 75.46; H 8.67%). HRMS (EI):
M 302.1881. Calcd for C19H26O3: 302.1882. IR (film) n
References and notes
1. (a) Aburel, P. S.; Undheim, K. J. Chem. Soc., Perkin Trans. 1
2000, 1891–1896. (b) Aburel, P. S.; Rømming, C.; Undheim,
K. J. Chem. Soc., Perkin Trans. 1 2001, 1024–1029.
2. Aburel, P. S.; Rømming, C.; Ma, K.; Undheim, K. J. Chem.
Soc., Perkin Trans. 1 2001, 1458–1472.
1
cmK1 2941 (s), 2884 (s), 1603 (w), 1492 (m); H NMR
(300 MHz, CDCl3) d 1.21–1.62 (8H, m, CH2), 1.79–1.90
(3H, m, CH2), 1.95–2.12 (3H, m, CH2), 2.61 (1H, q, JZ
7.2 Hz, H2 or H3), 3.03–3.31 (2H, m, H7 and H2 or H3),
3.46 (1H, dq, JZ6.9, 1.3 Hz, H2 or H3), 3.62 (1H, dq, JZ
7.3, 1.2 Hz, H3 or H2), 3.81 (3H, s, CH3), 6.80–6.84 (2H, m,
H-Ar), 7.02-7.06 (1H, m, H-Ar), 7.31 (1H, dd, JZ7.6,
1.7 Hz, H-Ar); 13C NMR (75 MHz, CDCl3) d 22.5 (CH2),
22.9 (CH2), 24.0 (CH2), 31.2 (CH2), 33.9 (CH2), 34.2 (CH2),
37.4 (CH2), 47.1 (C7), 53.8 (C6), 55.6 (CH3), 62.7 (C2 or C3),
63.1(C3 orC2), 110.1(C-Ar), 113.5 (C5), 119.3 (C-Ar), 125.6
(C-Ar), 130.2 (C-Ar), 134.1 (C-Ar), 157.7 (C-Ar); m/z (EI):
302 (M, 40%), 240 (48), 174 (73), 99 (100).
3. Nakayama, J.; Fujimori, T. J. Chem. Soc., Chem. Commun.
1991, 1614–1615.
4. Nieman, J. E.; Keay, B. A. Tetrahedron: Asymmetry 1995, 6,
1575–1583.
5. Falck-Pedersen, M.-L.; Undheim, K. Tetrahedron 1999, 55,
8525–8538.
6. Nieman, J. A.; Keay, B. A. Synth. Commun. 1999, 29,
3829–3840.
7. (a) Larock, R. C.; Oertle, K.; Potter, G. F. J. Am. Chem. Soc.
1980, 102, 190–197. (b) Barnhart, R. W.; Wang, X.; Noheda,
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9647–9648.
4.1.30. 1-(2-Methoxyphenyl)spiro[4.5]decan-6-one (35).
A solution of 7-(2-methoxyphenyl)-1,4-dioxadispiro-
[4.0.4.4]tetradecane (34). (0.069 g, 0.23 mmol) in 3 M
HCl (3 mL) and CH2Cl2 (4 mL) was stirred at room
temperature for. 5 h. Additional dichloromethane was
added, the two phases separated, the organic solution
dried (MgSO4) and evaporated. The residual material was
subjected to flash chromatography on silica gel using 10%
EtOAc in hexane. The product was a yellowish oil; yield
0.049 g (82%). (Found: C, 78.78; H 8.61. Calcd for
C17H22O2: C, 79.03; H 8.58%). HRMS(EI): M 258.1623.
Calcd for C17H22O2: 258.1620. IR (film) n cmK1: 2938 (s),
2866 (m), 1699 (s), 1492 (m); 1H NMR (300 MHz, CDCl3)
d 1.34–1.70 (6H, m, CH2), 1.72–1.99 (5H, m, CH2), 2.08–
2.17 (2H, m, CH2), 2.58–2.68 (1H, m, CH2), 3.79 (1H, dd,
JZ7.9, 6.9 Hz, H1), 3.81 (3H, s, CH3), 6.81–6.85 (2H, m,
H-Ar), 7.01 (1H, dd, JZ7.7, 1.7 Hz, H-Ar), 7.10-7.15 (1H,
m, H-Ar); 13C NMR (75 MHz, CDCl3) d 21.9 (CH2), 23.4
(CH2), 27.3 (CH2), 35.2 (CH2), 36.4 (CH2), 41.2 (CH2), 41.5
(CH2), 45.2 (C1), 55.3 (CH3), 62.1 (C5), 110.3 (C-Ar),
120.8 (C-Ar), 127.2 (C-Ar), 129.3 (C-Ar), 132.1 (C-Ar),
11. SMART and SAINT. Area-Detector Control and Integration
Software Version 5.054; Bruker Analytical X-ray Instruments
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14. Ates, A.; Gautier, A.; Leroy, B.; Plancher, J.-M.; Quesnel, Y.;
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8989–8999.