Electrophilic Phosphonium Cations as Lewis Acid Catalysts in Diels-Alder Reactions and Nazarov Cyclizations

Article abstract of DOI:10.1021/acs.organomet.8b00496

The highly electrophilic fluorophosphonium cation [(C₆F₅)₃PF]⁺[B(C₆F₅)₄]^- is shown to catalyze Diels-Alder reactions of challenging dienophile/enophile combinations an

Full text of DOI:10.1021/acs.organomet.8b00496

Article
pubs.acs.org/Organometallics
Cite This: Organometallics XXXX, XXX, XXX−XXX
Electrophilic Phosphonium Cations as Lewis Acid Catalysts in Diels−
Alder Reactions and Nazarov Cyclizations
†
Maria Vogler,† Lars Susse, James H. W. LaFortune,‡ Douglas W. Stephan,*,†,‡
̈
and Martin Oestreich*,†
†Institut fu
̈
r Chemie, Technische Universitat Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
̈
‡Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6
S
* Supporting Information
ABSTRACT: The highly electrophilic fluorophosphonium
cation [(C6F5)3PF]+[B(C6F5)4]− is shown to catalyze Diels−
Alder reactions of challenging dienophile/enophile combina-
tions and Nazarov cyclizations of various precursors. Several
other electrophilic phosphonium cations (EPCs) have been
tested for comparison. This systematic study demonstrates the
power of these Lewis acids to act as catalysts for synthetically
useful pericyclic reactions.
We disclose here EPC-catalyzed Diels−Alder reactions of
INTRODUCTION
■
challenging diene/dienophile combinations.11 Moreover, the
same EPC catalyst also promotes Nazarov cyclizations.
Electrophilic phosphonium cations (EPCs) have long been
known to act as Lewis acid catalysts.1,2 Their use in catalytic
carbon−carbon bond formation is one important application
(Scheme 1), and this was started by Mukaiyama and co-
workers three decades ago. Mukaiyama aldol reactions of
aldehydes and silyl enol ethers or silyl ketene acetals were
accomplished using the dicationic catalysts [R3POPR3]2+-
RESULTS AND DISCUSSION
■
EPC-Catalyzed Diels−Alder Reactions of Cyclohexa-
1,3-diene and α,β-Unsaturated Ketones. We started our
investigation with the Diels−Alder reaction of cyclohexa-1,3-
diene (10) and (E)-chalcone (9a) to yield cycloadduct 11a
(Table 1). Catalyst 67 had emerged as an optimal choice from
an earlier screening of various EPCs (see the Supporting
Information for further details). Additional examples include
12−18,4,12−16 and those highlighted in gray boxes performed
similarly to 6 (Figure 1). 6 was eventually chosen for its easy
accessibility.17
[OTf]2 (1, R = Bu; 2, R = Ph).3a These catalysts were also
−
shown to promote Michael reactions of enol ethers and allylic
silanes as well as Mannich-type reactions of imines and silyl
ketene acetals.3 Recently, the groups of Stephan and Alcarazo
reported the use of dicationic cyclopropenium- and pyridi-
nium-substituted phosphonium salts such as [Ph3P(2-
C5H4NMe)]2+[B(C6F5)4]2 (3) as competent catalysts for
−
Catalyst 6 converted a 2:1 combination of 10 and 9a into
cycloadduct 11a with 34% conversion after 24 h at room
temperature; the endo:exo ratio was high (Table 1, entry 1).
Successively increasing the amount of cyclohexa-1,3-diene
(10) and then the catalyst loading led to enhanced conversion,
reaching full conversion within 3 h with 8.0 equiv of 10 and 3.0
mol % of 6 (entries 2−6). Solvents other than 1,2-
chlorobenzene resulted in lower conversions (entries 7−9).
The fact that a large excess of diene 10 is necessary to reach
full conversion prompted us to look independently into the
Mukaiyama aldol reactions.4 Cyanosilylation of carbonyl
groups is another area of application for EPCs. Single examples
were realized with catalysts 13a and [Ph3PMe]+[I]− (4),5 and
slightly modified 4, that is [Ph3PBn]+[Cl]− (5), showed broad
substrate scope.6
Five years ago, Stephan and co-workers revived this field
with the introduction of the highly electrophilic fluorophos-
phonium cation [(C6F5)3PF]+[B(C6F5)4]− (6).7 Several
strongly Lewis acidic EPCs have been developed since
then.1a Applications include alkene hydroarylation8 and various
Friedel−Crafts alkylation reactions initiated by heterolytic C−
F bond cleavage.9 Given the high reactivity of Stephan’s EPCs,
we wondered whether these would be able to catalyze difficult
Diels−Alder reactions with cyclohexa-1,3-diene as a dien-
ophile. Of note, Terada and Kouchi had described the Diels−
Alder reaction of cyclopentadiene and amide dienophiles with
catechol-derived phosphonium salts such as 7 and 8 as
catalysts.10
1
reactant/catalyst combinations by H NMR spectroscopy. For
this, we mixed cyclohexa-1,3-diene (10), [(C6F5)3PF]+[B-
(C6F5)4]− (6), and mesitylene as internal standard and
analyzed this mixture after certain time intervals over a period
1
of 24 h. The H NMR analysis showed that two-thirds of 10
have been consumed after less than 1 h, and no 10 remained
Received: July 16, 2018
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.8b00496
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Article
Scheme 1. EPC-Catalyzed Carbon−Carbon Bond-Forming
Reactions and Representative Catalysts
Figure 1. EPCs tested in challenging Diels−Alder reactions (see the
Supporting Information for further details).
not catalytically active, we observed formation of the
cycloadduct 11a even when cyclohexa-1,3-diene (10) was
added to the dieneophile 9a and the catalyst 6 after its full
decomposition over several hours as monitored by 19F and 31
P
NMR spectroscopy. This experiment suggests that not only 6
but also in situ generated carbocations are potentially
promoting this Diels−Alder reaction.20
Although full conversion was achieved with 8.0 equiv of 10
after 3 h, we continued with using 6.0 equiv at a longer
reaction time (see Table 1, entries 5 and 6). We then examined
the scope of this Diels−Alder reaction for different α,β-
unsaturated ketones 9b−h (Scheme 2). Chalcone-derived 11a
had been obtained in 87% isolated yield before. An electron-
rich anisyl group at the carbonyl carbon atom had no effect,
and 11b was obtained in 88% yield. Conversely, a mesitylene
group thwarts the cycloaddition and 11c only formed in trace
amounts at a low conversion of 35%. The same trend was seen
with naphthyl substituents: the yield was high with the β-
naphthyl group (90% for 11d), and a diminished yield was
obtained for an α-naphthyl substituent (51% for 11e). An alkyl
group attached to the CO unit was also tolerated, and 11f
was isolated in near-quantitative yield. Cyclic enones such as
cyclopent-2-en-1-one (9g) and cyclohex-2-en-1-one (9h) are
considered particularly poor dienophiles, but EPC 6 was still
able to mediate their Diels−Alder reactions in decent yields of
63% (for 11g) and 72% (for 11h), respectively. Furthermore,
we extended the method to 2,3-dimethylbuta-1,3-diene (19) as
diene, and its reaction with 9a yielded cycloadduct 20a in good
yield and with high trans selectivity (gray box, Scheme 2).
EPC-Catalyzed Nazarov Cyclization. The Nazaraov
cyclization is another synthetically useful pericyclic reaction,21
and no examples of EPC catalysis have been reported. We
therefore tested catalyst 6 in the Nazarov cyclization with
alkoxy-substituted dienone 21a22 as model substrate (Table 2).
A catalyst loading of 3.0 mol % and a reaction time of 1 h at
room temperature in dichloromethane was sufficient for full
conversion (entry 1); the diastereoselectivity for 22a slightly
favoring cis was poor though. To increase the diastereose-
lectivity, we began testing different solvents. The use of
benzene led mainly to the trans product (entry 2). While the
increase from 43:57 to 84:16 was substantial, the ring closure
was less clean. These impurities were reduced with 1,2-
difluorobenzene as solvent, but the diastereomeric ratio
dropped to 61:39 (entry 3). However, diastereocontrol was
restored at a shorter reaction time (entry 4). Furthermore, a
Table 1. Optimization of the EPC-Catalyzed Diels−Alder
a b
,
Reaction
cd
,
diene 10
(equiv)
catalyst 6
(mol %)
conversn
(%)
entry
solvent
1
2
3
4
5
6
7
8
2.0
3.0
5.0
5.0
6.0
8.0
3.0
3.0
3.0
1.0
1.0
1.0
3.0
3.0
3.0
3.0
3.0
3.0
1,2-Cl2C6H4
1,2-Cl2C6H4
1,2-Cl2C6H4
1,2-Cl2C6H4
1,2-Cl2C6H4
1,2-Cl2C6H4
1,2-Cl2C6H4
ClC6H5
34
79
89
95 (90)
100 (87)
100
e
86
73
54
9
CD2Cl2
a
All reactions were performed according to General Procedure GP1
b
(see the Experimental Section). endo:exo ratio was determined by
GLC analysis prior to purification. Conversion of (E)-chalcone was
c
determined by GLC analysis using mesitylene as internal standard.
d
Isolated yield after flash column chromatography in parentheses.
e
Full conversion already after 3 h.
after 24 h (see the Supporting Information for details). The
1
obtained H NMR spectra indicated oligomerization of diene
10.18 Another observed side reaction was the deoxygenation of
9a by EPC 6, affording (C6F5)3PF2 and (C6F5)3PO.19
Although these newly formed phosphorus compounds are
B
DOI: 10.1021/acs.organomet.8b00496
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Article
Scheme 2. Substrate Scope of the EPC-Catalyzed Diels−
Table 3. Substrate Scope of the EPC-Catalyzed Nazarov
Cyclization of Activated Dienones
a c
−
a
Alder Reaction of Cyclohexa-1,3-diene
b
cd
,
entry
precursor
R
dr
yield of 22 (%)
1
2
3
4
5
6
21a
21b
21c
21d
21e
21f
Ph
4-BrC6H4
4-(CF3)C6H4
4-(OMe)C6H4
fur-2-yl
63:37
57:43
45:55
35:65
55:45
51:49
23 (22a)
35 (22b)
41 (22c)
30 (22d)
26 (22e)
28 (22f)
thien-2-yl
a
All reactions were performed according to General Procedure GP3
b
(see the Experimental Section). trans:cis ratio was determined by 1H
NMR analysis prior to purification. Combined isolated yield of both
c
diastereomers after flash column chromatography on silica gel.
d
Isolated with inseparable unknown impurities.
EPC 6 to engage in deoxygenation19 could be an explanation
for the mediocre yields (see above). To verify this, we again
performed independent NMR experiments with substrate/
catalyst and product/catalyst combinations, respectively. Our
assumption proved to be true, as we observed the
deoxygenation of both cyclization precursor 21a and cyclized
product 22a; catalyst 6 again decomposed to (C6F5)3PF2 and
(C6F5)3PO (see the Supporting Information for details). It is
important to mention that these new phosphorus compounds
are not catalytically active in this Nazarov cyclization.
a
All reactions were performed according to General Procedure GP1
b
(see the Experimental Section). endo:exo ratio was determined by
GLC analysis prior to purification. Diastereomeric ratio (trans:cis)
was determined by GLC analysis prior to purification. 2,3-
Dimethylbuta-1,3-diene (19) was used instead of cyclohexa-1,3-diene.
c
d
Unactivated dienones 23a−f23 are devoid of the ether
oxygen atom present in 21a−f, and these cyclization precursors
showed higher yields in Nazarov cyclizations under otherwise
identical reaction conditions (Table 4). In this ring closure,
trans-24a was obtained along with regioisomer 25a. For
example, 23a cyclized with a 85:15 regioisomeric ratio in 96%
combined yield (entry 1). Related compounds 24b−d and
25b−d with an aromatic substituent in the β-position were
Table 2. Optimization of the EPC-Catalyzed Nazarov
Reaction
a
Table 4. Substrate Scope of the EPC-Catalyzed Nazarov
a
Cyclization of Unactivated Dienones
b
entry
catalyst 6 (mol %)
solvent
t (min)
dr
1
2
3
4
5
6
3.0
3.0
3.0
3.0
1.0
5.0
CH2Cl2
C6H6
1,2-F2C6H4
1,2-F2C6H4
1,2-F2C6H4
1,2-F2C6H4
60
60
60
30
60
60
43:57
84:16
61:39
89:11
51:49
87:13
a
c
combined yield of
All reactions were performed according to General Procedure GP3
b
b
(see the Experimental Section). trans:cis ratio was determined by 1H
NMR analysis prior to purification.
entry precursor
R
24:25
24/25 (%)
1
2
3
4
5
6
23a
23b
23c
23d
23e
23f
Ph
85:15
83:17
88:12
84:16
53:47
64:36
96 (24a/25a)
77 (24b/25b)
82 (24c/25c)
59 (24d/25d)
63 (24e/25e)
80 (24f/25f)
4-BrC6H4
4-(CF3)C6H4
4-(OMe)C6H4
fur-2-yl
lower catalyst loading of 1.0 mol % was detrimental, while 5.0
mol % of 6 had no negative effect (entries 5 and 6).
We then examined the substrate scope under the optimized
reaction conditions (Table 2, entry 4) with different
(hetero)aromatic substituents in the β-position of alkoxy-
substituted dienones 21a−f (Table 3). The isolated yields of
cyclized 22a−f were rather low throughout; these ring closures
proceeded essentially with no diastereocontrol. The ability of
thien-2-yl
a
All reactions were performed according to General Procedure GP3
b
(see the Experimental Section). Regioisomeric ratio determined by
c
1H NMR analysis prior to purification. Combined isolated yield of
both regioisomers after flash column chromatography on silica gel.
C
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1H NMR; C6D6, δ 128.06 ppm for 13C NMR; 1,2-Cl2C6D3H, δ 6.94
and 7.20 ppm for H NMR; 1,2-Cl2C6D4, δ 127.1, 130.1, and 132.5
generally formed with a regioselectivity of approximately 85:15
(entries 2−4). The use of more electron donating groups such
as fur-2-yl and thien-2-yl shifts the ratio more toward the
regioisomers 25e,f with the higher substituted double bond
(entries 5 and 6). A reason for this could be the changed
polarization in the divinyl ketone.24 Again, the yields are lower
of ether-oxygen-containing systems such as 23d,e (entries 4
and 5); the effect is less pronounced, but yields dwindled from
around 80% to 59% and 63%, respectively.
1
ppm for 13C NMR).30 NMR data are reported as follows: chemical
shift, multiplicity (s = singlet, d = doublet, dd = doublet of doublets, t
= triplet, q = quartet, m = multiplet, mc = centrosymmetric multiplet),
coupling constant (Hz), and integration. Infrared (IR) spectra were
recorded on an Agilent Technologies Cary 630 FTIR spectropho-
tometer equipped with an ATR unit and are reported as wavenumbers
(cm−1) (w = weak, m = medium, s = strong). Gas−liquid
chromatography (GLC) was performed on an Agilent Technologies
7820A gas chromatograph equipped with an HP-5 capillary column
(30 m × 0.32 mm, 0.25 μm film thickness) using the following
program: N2, carrier gas; injection temperature, 240 °C; detector
temperature, 300 °C; flow rate, 1.74 mL/min; temperature program,
start temperature 40 °C, heating rate 10 °C/min, end temperature
280 °C for 10 min. Melting points (mp) were determined with a
Stuart Scientific SMP20 melting point apparatus and are not
corrected. High-resolution mass spectrometry (HRMS) was per-
The Nazarov cyclization of precursor 2625 bearing an
electron-withdrawing group in the α-position was successfully
catalyzed by catalyst 6 to afford 27 in 60% yield (Scheme 3).
The diastereoselectivity in favor of the trans isomer was high.
Scheme 3. Nazarov Cyclization of Divinyl Ketone with
a b
,
Electron-Withdrawing Group
formed at the Analytical Facility at the Institut fur Chemie,
̈
̈
Technische Universitat Berlin.
General Procedure for Diels−Alder Reactions Catalyzed by
[(C6F5)3PF]+[B(C6F5)4]− (6) (GP1). In a glovebox, a flame-dried GLC
vial equipped with a magnetic stir bar was charged with the
corresponding diene (0.49 mmol, 6.0 equiv), the indicated dienophile
(82 μmol, 1.0 equiv), and 1,2-Cl2C6H4 (0.1 mL). To this mixture was
added a solution of [(C6F5)3PF]+[B(C6F5)4]− (6; 2.5 μmol, 3.0 mol
%) in 1,2-Cl2C6H4 (0.1 mL). After the reaction mixture was stirred for
24 h, the cycloadduct was purified by flash column chromatography
on silica gel using a cyclohexane/dichloromethane or n-pentane/ethyl
acetate mixture as eluent.
a
The reaction was performed according to General Procedure GP3
b
(see the Experimental Section). trans:cis ratio was determined by 1H
NMR analysis prior to purification.
General Procedure for the Preparation of Divinyl Ketones
(GP2). According to a procedure modified from that of Rawal,23
tBuLi (1.70−1.82 M in pentane, 1.09−1.10 equiv) was added
dropwise to a THF solution of 3,4-dihydro-2H-pyran or 1-
bromocyclohex-1-ene (1.00 equiv) at −78 °C. After stirring of the
reaction mixture for 30 min at 0 °C, a solution of the indicated
aldehyde (1.10 equiv) in THF was added at −78 °C. The resulting
mixture was stirred for 2 h at 0 °C, quenched with water (50 mL), and
diluted with tert-butyl methyl ether (50 mL). After separation of the
layers, the water phase was extracted with tert-butyl methyl ether (3 ×
50 mL) and the combined organic phases were washed with brine (20
mL), dried over MgSO4, and concentrated under reduced pressure.
The purification of the residue by flash column chromatography on
silica gel using cyclohexane/ethyl acetate or cyclohexane/tert-butyl
methyl ether mixtures as eluent afforded the corresponding diallyl
alcohol. To a solution of the diallyl alcohol (1.0 equiv) in
dichloromethane and pyridine was added successively Dess−Martin
periodinane (1.1 equiv) at room temperature. After stirring of the
mixture for 2 h at room temperature, the reaction was quenched by
addition of a solution of aqueous NaOH (2 M, 50 mL). The resulting
solution was stirred for 30 min. The layers were separated, and the
aqueous phase was extracted with dichloromethane (3 × 50 mL). The
combined organic layers were washed with brine (100 mL), dried
over MgSO4, and concentrated under reduced pressure. The residue
was purified by flash column chromatography on silica gel using a
cyclohexane/ethyl acetate or n-pentane/tert-butyl methyl ether
mixture as eluent.
CONCLUSION
■
This systematic study shows that electrophilic phosphonium
cations (EPCs) promote pericyclic reactions. The EPC 6 was
identified as sufficiently Lewis acidic to catalyze difficult Diels−
Alder reactions of cyclohexa-1,3-dienes as well as Nazarov
cyclizations of activated and unactivated divinyl ketones.
EXPERIMENTAL SECTION
■
General Information. All reactions were performed in flame-
dried glassware using an MBraun glovebox or conventional Schlenk
techniques under a static pressure of argon (glovebox) or nitrogen.
Liquids and solutions were transferred with syringes and cannulas.
Solvents were dried and purified using standard procedures. Technical
grade solvents for extraction or chromatography were distilled prior to
use. C6D6, CDCl3, and CD2Cl2 were dried over 4 Å molecular sieves.
1,2-Cl2C6D4, cyclohexa-1,3-diene (10), and 2,3-dimethylbuta-1,3-
diene (19) were dried over CaH2, distilled, degassed, and stored
under argon. Cyclopent-2-en-1-one and cyclohex-2-en-1-one were
condensed, degassed, and stored under argon. Catalyst 6 was
synthesized according to a literature procedure.7 α,β-Unsaturated
ketones 9a,d,e26,27 for Diels−Alder reactions as well as α,β-
unsaturated aldehydes,28 1-bromocyclohex-1-ene,29 diallyl alcohols,22
their corresponding divinyl ketones 21a−f and 23a−f,23 and divinyl
ketone 2625 for Nazarov reactions were prepared according to
literature procedures. Other chemicals not previously mentioned were
purchased from commercial suppliers and used without further
purification. Analytical thin layer chromatography (TLC) was
performed on silica gel 60 F254 aluminum sheets from Merck using
the indicated solvents. Flash column chromatography was performed
on silica gel 60 (40−63 μm, 230−400 mesh, ASTM) from Merck
General Procedure for Nazarov Cyclizations Catalyzed by
[(C6F5)3PF]+[B(C6F5)4]− (6) (GP3). In a glovebox, a flame-dried GLC
vial equipped with a magnetic stir bar was charged with the
corresponding divinyl ketone (0.082 mmol, 1.0 equiv) and 1,2-
F2C6H4 (0.1 mL). To this mixture was added a solution of
[(C6F5)3PF]+[B(C6F5)4]− (6; 2.5 μmol, 3.0 mol %) in 1,2-F2C6H4
(0.1 mL). After stirring of the reaction mixture for 30 min, the
product was purified by flash column chromatography on silica gel
using a cyclohexane/dichloromethane or cyclohexane/tert-butyl
methyl ether mixture as eluent.
using the indicated solvents. H, 13C, 11B, 19F, and 31P NMR spectra
1
were recorded in CDCl3, CD2Cl2, C6D6, or 1,2-Cl2C6D4 on Bruker
AV400 and Bruker AV500 instruments. Chemical shifts are reported
in parts per million (ppm) and are referenced to the residual solvent
resonance as the internal standard (CHCl3, δ 7.26 ppm for 1H NMR;
endo-Phenyl(3-phenylbicyclo[2.2.2]oct-5-en-2-yl)methanone
(11a). Prepared from (E)-chalcone (9a; 17 mg, 82 μmol, 1.0 equiv),
cyclohexa-1,3-diene (10; 39 mg, 0.49 mmol, 6.0 equiv), and
CDCl3, δ 77.16 ppm for 13C NMR; CDHCl2, δ 5.32 ppm for H
1
NMR; CD2Cl2, δ 53.84 ppm for 13C NMR; C6D5H, δ 7.16 ppm for
D
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[(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %) according
to GP1. The product 11a (20.6 mg, 71.0 μmol, 87%) was obtained as
a white solid after purification by flash column chromatography on
silica gel using cyclohexane/dichloromethane (100/0 → 80/20) as
eluent. Rf = 0.47 (cyclohexane/dichloromethane = 1/1). Mp: 118 °C
cyclohexane/dichloromethane (100/0 → 80/20) as eluent. Rf = 0.53
(cyclohexane/dichloromethane = 1/1). GLC (HP-5): tR = 30.9 min.
IR (ATR): ν
̃
2925 (w), 2859 (w), 1681 (s), 1229 (w), 1100 (m), 802
(m), 777 (s), 750 (m), 698 (s) cm−1. HRMS (APCI, m/z): calculated
for C25H23O+ [M + H]+, 339.1743; found, 339.1738. H NMR (500
1
MHz, CDCl3): δ 1.04−1.12 (m, 1H), 1.38−1.45 (m, 1H), 1.75−1.82
(m, 2H), 2.65−2.66 (m, 1H), 2.92−2.93 (m, 1H), 3.55−3.56 (m,
1H), 3.76−3.78 (m, 1H), 6.17−6.21 (m, 1H), 6.60−6.64 (m, 1H),
7.21−7.25 (m, 1H), 7.28−7.38 (m, 5H), 7.51−7.53 (m, 3H), 7.85−
7.87 (m, 1H), 7.89 (d, J = 8.3 Hz, 1H), 8.10−8.12 (m, 1H). 13C{1H}
NMR (126 MHz, CDCl3): δ 18.8, 26.4, 33.8, 37.0, 44.4, 55.3, 124.4,
125.5, 125.6, 126.3, 126.5, 127.5, 128.3 (2C), 128.5, 128.6 (2C),
130.6, 131.0, 131.3, 133.9, 137.0, 137.7, 143.0, 205.5. The analytical
and spectroscopic data are in accordance with those reported.27
endo-1-(3-Phenylbicyclo[2.2.2]oct-5-en-2-yl)ethan-1-one (11f).
Prepared from (E)-4-phenylbut-3-en-2-one (9f; 12 mg, 82 μmol,
1.0 equiv), cyclohexa-1,3-diene (10; 39 mg, 0.49 mmol, 6.0 equiv),
and [(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %)
according to GP1. The product 11f (18.2 mg, 80.0 μmol, 98%) was
obtained as a yellow oil after purification by flash column
chromatography on silica gel using cyclohexane/dichloromethane
(100/0 → 2/1) as eluent. Rf = 0.37 (cyclohexane/dichloromethane =
(n-pentane). GLC (HP-5): tR = 24.4 min. IR (ATR): ν 2926 (w),
̃
2863 (w), 1672 (s), 1595 (w), 1446 (m), 1216 (m), 960 (m), 746
(s), 689 (s) cm−1. HRMS (APCI, m/z): calculated for C21H21O+ [M
1
+ H]+, 289.1587; found, 289.1582. H NMR (500 MHz, CDCl3): δ
1.10−1.16 (m, 1H), 1.46−1.52 (m, 1H), 1.81−1.86 (m, 1H), 1.88−
1.94 (m, 1H), 2.67−2.68 (m, 1H), 2.97−2.99 (m, 1H), 3.48−3.49
(m, 1H), 3.80−3.82 (m, 1H), 6.11−6.13 (m, 1H), 6.56−6.59 (m,
1H), 7.19−7.23 (m, 1H), 7.29−7.34 (m, 4H), 7.38−7.41 (m, 2H),
7.49−7.53 (m, 1H), 7.86−7.88 (m, 2H). 13C{1H} NMR (126 MHz,
CDCl3): δ 18.7, 26.6, 34.7, 36.6, 44.9, 51.1, 126.3, 128.3 (2C), 128.6
(4C), 128.6 (2C), 130.8, 132.8, 136.4, 136.6, 143.0, 200.9. The
analytical and spectroscopic data are in accordance with those
reported.27
endo-(2-Methoxyphenyl)(3-phenylbicyclo[2.2.2]oct-5-en-2-yl)-
methanone (11b). Prepared from (E)-1-(2-methoxyphenyl)-3-
phenylprop-2-en-1-one (9b; 19.5 mg, 82.0 μmol, 1.00 equiv),
cyclohexa-1,3-diene (10; 39 mg, 0.49 mmol, 6.0 equiv), and
[(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %) according
to GP1. The product 11b (22.8 mg, 72.0 μmol, 88%) was obtained as
a colorless oil after purification by flash column chromatography on
silica gel using cyclohexane/dichloromethane (100/0 → 80/20 →
50/50) as eluent. Rf = 0.26 (cyclohexane/dichloromethane = 1/1).
1/1). GLC (HP-5): tR = 18.6 min. IR (ATR): ν 2941 (w), 2866 (w),
̃
1704 (s), 1353 (m), 1163 (m), 748 (m), 700 (s), 667 (m) cm−1.
HRMS (APCI, m/z): calculated for C16H19O+ [M + H]+, 227.1430;
1
found, 227.1426. H NMR (500 MHz, CDCl3): δ 1.00−1.06 (m,
1H), 1.43−1.48 (m, 1H), 1.65−1.76 (m, 2H), 2.03 (s, 3H), 2.52−
2.54 (m, 1H), 2.93−2.94 (m, 1H), 3.01−3.02 (m, 1H), 3.12−3.13
(m, 1H), 6.20−6.23 (m,1H), 6.46−6.49 (m, 1H), 7.22−7.25 (m,
1H), 7.28−7.29 (m, 2H), 7.33−7.36 (m, 2H). 13C{1H} NMR (126
MHz, CDCl3): δ 18.5, 26.1, 28.5, 32.7, 37.3, 45.6, 56.6, 126.5, 128.2
(2C), 128.6 (2C), 131.6, 136.1, 142.8, 209.0. The analytical and
spectroscopic data are in accordance with those reported.27
GLC (HP-5): tR = 25.9 min. IR (ATR): ν 2938 (w), 2863 (w), 1672
̃
(m), 1595 (m), 1483 (m), 1460 (m), 1434 (m), 1282 (m), 1242 (s),
1019 (m), 961 (m), 750 (s), 699 (s) cm−1. HRMS (APCI, m/z):
+
1
calculated for C22H23O2 [M + H]+, 319.1693; found, 319.1686. H
NMR (500 MHz, CDCl3): δ 1.03−1.09 (m, 1H), 1.40−1.45 (m, 1H),
1.71−1.80 (m, 2H), 2.60−2.61 (m, 1H), 2.96−2.97 (m, 1H), 3.40−
3.42 (m, 1H), 3.70 (s, 3H), 3.90−3.91 (m, 1H), 6.11−6.14 (m, 1H),
6.52−6.55 (m, 1H), 6.83 (d, J = 8.3 Hz, 1H), 6.95−6.97 (m, 1H),
7.17−7.20 (m, 1H), 7.25−7.32 (m, 4H), 7.35−7.39 (m, 1H), 7.43
(dd, J = 7.6 Hz, J = 1.7 Hz, 1H). 13C{1H} NMR (126 MHz, CDCl3):
δ 18.7, 26.5, 33.5, 37.0, 44.8, 55.0, 55.4, 111.3, 120.8, 126.0, 128.3
(2C), 128.3 (2C), 129.3, 130.1, 131.3, 132.4, 136.6, 143.4, 157.4,
204.5. The analytical and spectroscopic data are in accordance with
those reported.27
endo-Tricyclo[5.2.2.02,6]undec-8-en-3-one (11g). Prepared from
cyclopent-2-en-1-one (9g; 13 mg, 0.16 mmol, 1.0 equiv), cyclohexa-
1,3-diene (10; 78 mg, 0.97 mmol, 6.0 equiv), and [(C6F5)3PF]+[B-
(C6F5)4]− (6; 6.2 mg, 5.0 μmol, 3.0 mol %) according to GP1. The
product 11g (16.8 mg, 0.100 mmol, 63%) was obtained as a yellow oil
after purification by flash column chromatography on silica gel using
n-pentane/ethyl acetate (40/1) as eluent. Rf = 0.27 (cyclohexane/
ethyl acetate = 20/1). GLC (HP-5): tR = 13.0 min. IR (ATR): ν 2931
̃
(w), 2865 (w), 1726 (s), 1167 (m), 708 (s) cm−1. HRMS (APCI, m/
z): calculated for C11H15O+ [M + H]+, 163.1117; found, 163.1115.
1H NMR (500 MHz, CDCl3): δ 1.22−1.30 (m, 2H), 1.46−1.59 (m,
3H), 1.94−2.12 (m, 3H), 2.35−2.38 (mc, 1H), 2.52−2.58 (m, 1H),
2.64−2.65 (m, 1H), 2.93−2.95 (m, 1H), 6.14−6.17 (m, 1H), 6.20−
6.23 (m, 1H). 13C{1H} NMR (126 MHz, CDCl3): δ 24.2, 24.9, 26.2,
32.6, 35.6, 38.3, 39.8, 52.5, 133.7, 133.9, 222.9. The analytical and
spectroscopic data are in accordance with those reported.11
endo-Naphthalen-2-yl(3-phenylbicyclo[2.2.2]oct-5-en-2-yl)-
methanone (11d). Prepared from (E)-1-(naphthalen-2-yl)-3-phenyl-
prop-2-en-1-one (9d; 21 mg, 82 μmol, 1.0 equiv), cyclohexa-1,3-diene
(10; 39 mg, 0.49 mmol, 6.0 equiv), and [(C6F5)3PF]+[B(C6F5)4]− (6;
3.1 mg, 2.5 μmol, 3.0 mol %) according to GP1. The product 11d
(24.9 mg, 74.0 μmol, 90%) was obtained as a yellow solid after
purification by flash column chromatography on silica gel using
cyclohexane/dichloromethane (100/0 → 80/20) as eluent. Rf = 0.53
(cyclohexane/dichloromethane = 1/1). Mp: 151 °C (n-pentane).
endo-Tricyclo[6.2.2.02,7]dodec-9-en-3-one (11h). Prepared from
cyclohex-2-en-1-one (9h; 15 mg, 0.16 mmol, 1.0 equiv), cyclohexa-
1,3-diene (10; 77 mg, 0.96 mmol, 6.0 equiv), and [(C6F5)3PF]+[B-
(C6F5)4]− (6; 5.9 mg, 4.8 μmol, 3.0 mol %) according to GP1. The
product 11h (20.2 mg, 0.110 mmol, 69%) was obtained as a yellow oil
after purification by flash column chromatography on silica gel using
n-pentane/ethyl acetate (40/1) as eluent. Rf = 0.28 (cyclohexane/
GLC (HP-5): tR = 33.0 min. IR (ATR): ν 2926 (w), 2863 (w), 1671
̃
(s), 1451 (w), 1184 (w), 829 (m), 745 (s), 696 (s) cm−1. HRMS
(APCI, m/z): calculated for C25H23O+ [M + H]+, 339.1743; found,
339.1739. 1H NMR (500 MHz, CDCl3): δ 1.13−1.20 (m, 1H), 1.50−
1.57 (m, 1H), 1.86−1.92 (m, 1H), 1.94−1.99 (m, 1H), 2.68−2.70
(m, 1H), 3.06−3.08 (m, 1H), 3.45 (mc, 1H), 3.94 (mc, 1H), 6.22 (mc,
1H), 6.57 (mc, 1H), 7.23−7.25 (m, 1H), 7.33−7.35 (m, 4H), 7.49
(mc, 1H), 7.57 (mc, 1H), 7.74 (d, J = 8.2 Hz, 1H), 7.84 (d, J = 8.6 Hz,
2H), 7.97 (dd, J = 8.6 Hz, J = 1.7 Hz, 1H), 8.25 (s, 1H). 13C{1H}
NMR (126 MHz, CDCl3): δ 18.8, 26.4, 34.5, 36.7, 45.5, 51.7, 124.6,
126.4, 126.7, 127.8, 128.4 (4C), 128.7 (2C), 129.6, 130.2, 131.5,
132.6, 133.7, 135.5, 136.0, 143.2, 201.0. The analytical and
spectroscopic data are in accordance with those reported.27
ethyl acetate = 20/1); GLC (HP-5): tR = 14.6 min. IR (ATR): ν 2931
̃
(m), 2866 (w), 1700 (s), 713 (m) cm−1. HRMS (APCI, m/z):
1
calculated for C12H17O+ [M + H]+, 177.1274; found, 177.1269. H
NMR (500 MHz, CDCl3): δ 0.91−0.99 (m, 1H), 1.25−1.32 (m, 2H),
1.48−1.52 (m, 1H), 1.55−1.59 (m, 1H), 1.69−1.82 (m, 3H), 2.03−
2.11 (m, 1H), 2.32−2.35 (m, 1H), 2.36−2.41 (m, 1H), 2.42−2.44
(m, 1H), 2.50 (mc, 1H), 3.08 (mc, 1H), 6.12 (mc, 1H), 6.25 (mc, 1H).
13C{1H} NMR (126 MHz, CDCl3): δ 20.9, 24.1, 26.1, 29.7, 31.3,
endo-Naphthalen-1-yl(3-phenylbicyclo[2.2.2]oct-5-en-2-yl)-
methanone (11e). Prepared from (E)-1-(naphthalen-1-yl)-3-phenyl-
prop-2-en-1-one (9e; 21 mg, 82 μmol, 1.0 equiv), cyclohexa-1,3-diene
(10; 39 mg, 0.49 mmol, 6.0 equiv), and [(C6F5)3PF]+[B(C6F5)4]− (6;
3.1 mg, 2.5 μmol, 3.0 mol %) according to GP1. The product 11e
(14.2 mg, 42.0 μmol, 51%) was obtained as a yellow oil after
purification by flash column chromatography on silica gel using
36.0, 38.9, 42.3, 53.1, 133.2, 134.6, 214.6. The analytical and
spectroscopic data are in accordance with those reported.11
(3,4-Dimethyl-6-phenylcyclohex-3-en-1-yl)phenylmethanone
(20a). Prepared from (E)-chalcone (9a; 17 mg, 82 μmol, 1.0 equiv),
2,3-dimethylbuta-1,3-diene (19; 40 mg, 0.49 mmol, 6.0 equiv), and
[(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %) according
E
DOI: 10.1021/acs.organomet.8b00496
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
to GP1. The product 20a (18.3 mg, 63.0 μmol, 77%) was obtained as
a colorless oil after purification by flash column chromatography on
silica gel using n-pentane/ethyl acetate (40/1) as eluent. Rf = 0.40
(cyclohexane/ethyl acetate = 20/1). GLC (HP-5): tR = 24.0 min. IR
and Dess−Martin periodinane (0.90 g, 2.1 mmol, 1.1 equiv)
according to GP2. The product 21d (0.32 g, 1.2 mmol, 63%) was
obtained as a yellow oil after purification by flash column
chromatography on silica gel using cyclohexane/tert-butyl methyl
ether (100/1 → 10/1) as eluent. Rf = 0.27 (cyclohexane/tert-butyl
(ATR): ν
̃
2926 (w), 1673 (m), 1446 (m), 758 (m), 696 (s) cm−1.
HRMS (APCI, m/z): calculated for C21H23O+ [M + H]+, 291.1743;
found, 291.1735. 1H NMR (500 MHz, CDCl3): δ 1.69 (s, 6H), 2.25−
2.37 (m, 4H), 3.30 (mc, 1H), 4.00 (td, J = 10.7 Hz, J = 5.4 Hz, 1H),
7.06 (mc, 1H), 7.14−7.20 (m, 4H), 7.38 (mc, 2H), 7.48 (mc, 1H),
7.81−7.83 (m, 2H). 13C{1H} NMR (126 MHz, CDCl3): δ 18.8, 18.9,
37.1, 40.8, 43.2, 47.6, 124.3, 125.8, 126.3, 127.5 (2C), 128.2 (2C),
128.4 (2C), 128.6 (2C), 132.8, 137.5, 144.8, 203.6. The analytical and
spectroscopic data are in accordance with those reported.11
(E)-1-(3,4-Dihydro-2H-pyran-6-yl)-2-methyl-3-(4-
(trifluoromethyl)phenyl)prop-2-en-1-one (21c). Prepared from 3,4-
dihydro-2H-pyran (0.46 g, 0.50 mL, 5.5 mmol, 1.0 equiv), tBuLi (1.7
M in pentane, 3.5 mL, 6.0 mmol, 1.1 equiv), and the crude (E)-2-
methyl-3-(4-(trifluoromethyl)phenyl)acrylaldehyde (1.31 g, ∼1.11
equiv) in THF (3 mL) according to GP2. (E)-1-(3,4-Dihydro-2H-
pyran-6-yl)-2-methyl-3-(4-(trifluoromethyl)phenyl)prop-2-en-1-ol
(0.84 g, 2.8 mmol, 24% over two steps) was obtained as a yellow oil
after purification by flash column chromatography on silica gel using
cyclohexane/tert-butyl methyl ether (20/1 → 10/1) as eluent. IR
methyl ether = 3/1). IR (ATR): ν 1598 (s), 1508 (s), 1300 (m), 1249
̃
(s), 1174 (s), 1057 (s), 1014 (s), 904 (m), 827 (m) cm−1. HRMS
+
(APCI, m/z): calculated for C16H19O3 [M + H]+: 259.1329; found,
1
259.1331. H NMR (500 MHz, C6D6): δ 1.31−1.37 (m, 2H), 1.72
(mc, 2H), 2.21 (d, J = 1.3 Hz, 3H), 3.26 (s, 3H), 3.68−3.72 (m, 2H),
5.72 (t, J = 4.2 Hz, 1H), 6.71 (mc, 2H), 7.21 (mc, 2H), 7.54 (s, 1H).
13C{1H} NMR (126 MHz, C6D6): δ 14.7, 20.8, 22.0, 54.8, 66.0, 109.3,
114.2 (2C), 129.2, 131.7 (2C), 134.7, 139.4, 152.8, 160.1, 192.3.
(E)-1-(Cyclohex-1-en-1-yl)-2-methyl-3-(4-(trifluoromethyl)-
phenyl)prop-2-en-1-one (23c). Prepared from 1-bromocyclohex-1-
ene (1.00 g, 6.21 mmol, 1.00 equiv) in THF (4 mL), tBuLi (1.82 M in
pentane, 3.70 mL, 6.77 mmol, 1.09 equiv), and (E)-2-methyl-3-(4-
(trifluoromethyl)phenyl)acrylaldehyde (1.46 g, 6.83 mmol, 1.10
equiv) in THF (2 mL) according to GP2. (E)-1-(Cyclohex-1-en-1-
yl)-2-methyl-3-(4-(trifluoromethyl)phenyl)prop-2-en-1-ol (0.59 g, 2.0
mmol, 32%) was obtained as a yellow oil after purification by flash
column chromatography on silica gel using cyclohexane/ethyl acetate
(20/1 → 10/1) as eluent. Rf = 0.19 (cyclohexane/ethyl acetate = 90/
(ATR): ν 2931 (w), 2851 (w), 1613 (w), 1321 (s), 1160 (m), 1108
̃
10). GLC (HP-5): tR = 20.0 min. IR (ATR): ν 3363 (w), 2925 (w),
̃
2857 (w), 1613 (w), 1320 (s), 1161 (m), 1107 (s), 1065 (s), 1014
(s), 1063 (s), 1014 (m) cm−1. HRMS (APCI, m/z): calculated for
+
1
C16H18F3O2 [M + H]+, 299.1253; found, 299.1251. H NMR (500
MHz, C6D6): δ 1.36−1.45 (m, 2H), 1.76−1.79 (m, 5H), 1.81−1.84
(m, 1H), 3.66 (mc, 2H), 4.43 (mc, 1H), 4.77 (t, J = 3.8 Hz, 1H), 6.62
(s, 1H), 7.05 (d, J = 8.2 Hz, 2H), 7.33 (d, J = 8.2 Hz, 2H). 13C{1H}
NMR (126 MHz, C6D6): δ 14.4, 20.2, 22.6, 66.3, 77.5, 97.3, 125.2 (q,
+
(m), 838 (w) cm−1. HRMS (APCI, m/z): calculated for C17H18F3
[M − OH]+, 279.1355; found, 279.1354. 1H NMR (500 MHz,
C6D6): δ 1.05 (s, 1H), 1.43−1.50 (m, 2H), 1.50−1.56 (m, 2H), 1.59
(d, J = 1.3 Hz, 3H), 1.75−1.80 (m, 1H), 1.92−1.96 (m, 3H), 4.21 (s,
1H), 5.69−5.71 (m, 1H), 6.55 (s, 1H), 7.03 (d, J = 8.2 Hz, 2H), 7.36
(d, J = 8.2 Hz, 2H). 13C{1H} NMR (126 MHz, C6D6): δ 14.3, 23.0,
3JC,F = 3.6 Hz, 2C), 125.4, 127.4 (q, JC,F = 288 Hz), 129.5 (2C),
1
1
140.6, 141.9, 154.0. One quaternary C atom could not be detected.
19F{1H} NMR (471 MHz, C6D6): δ = −62.1. The previously
prepared diallyl alcohol (0.72 g, 2.4 mmol, 1.0 equiv) in dichloro-
methane (50 mL) was then reacted with pyridine (2 mL) and Dess−
Martin periodinane (1.4 g, 3.3 mmol, 1.4 equiv) according to GP2.
The product 21c (0.41 g, 1.4 mmol, 58%) was obtained as a yellow
solid after purification by flash column chromatography on silica gel
using n-pentane/tert-butyl methyl ether (100/1 → 20/1) as eluent. IR
23.1, 24.3, 25.4, 80.9, 124.1, 124.4, 125.2 (q, JC,F = 272 Hz), 125.3
(q, JC,F = 3.9 Hz, 2C), 129.5 (2C), 138.2, 141.2, 142.0. 19F NMR
3
(471 MHz, C6D6): δ −62.0. One quaternary C atom could not be
detected. The previously prepared diallyl alcohol (0.500 g, 1.69 mmol,
1.00 equiv) in dichloromethane (25 mL) was then reacted with
pyridine (1 mL) and Dess−Martin periodinane (0.790 g, 1.86 mmol,
1.10 equiv) according to GP2. The product 23c (0.267 g, 0.910
mmol, 54%) was obtained as a yellow oil after purification by flash
column chromatography on silica gel using cyclohexane/ethyl acetate
(20/1) as eluent. Rf = 0.47 (cyclohexane/ethyl acetate = 10/1). GLC
(ATR): ν 1650 (m), 1615 (m), 1320 (s), 1256 (m), 1163 (m), 1110
̃
(s), 1063 (s), 1012 (s), 908 (m), 843 (m) cm−1. HRMS (APCI, m/
z): calculated for C16H16F3O2+ [M + H]+, 297.1097; found, 297.1091.
1H NMR (500 MHz, CDCl3): δ 1.89−1.96 (m, 2H), 2.12 (d, J = 1.4
Hz, 3H), 2.24−2.30 (m, 2H), 4.15−4.18 (m, 2H), 5.86 (t, J = 4.2 Hz,
1H), 7.20 (s, 1H), 7.49 (d, J = 8.2 Hz, 2H), 7.64 (d, J = 8.2 Hz, 2H).
13C{1H} NMR (126 MHz, CDCl3): δ 15.0, 21.1, 21.7, 66.6, 113.7,
(HP-5): tR = 20.0 min. IR (ATR): ν 2931 (w), 1629 (s), 1320 (s),
̃
1235 (m), 1162 (m), 1119 (s), 1065 (s), 1005 (m), 821 (m) cm−1.
HRMS (APCI, m/z): calculated for C17H18F3O+ [M + H]+, 295.1304;
1
found, 295.1306. H NMR (500 MHz, CD2Cl2): δ 1.64−1.69 (m,
2H), 1.69−1.74 (m, 2H), 2.08 (d, J = 1.5 Hz, 3H), 2.25−2.30 (m,
2H), 2.30−2.33 (m, 2H), 6.68−6.70 (m, 1H), 6.99 (s, 1H), 7.52 (d, J
= 8.2 Hz, 2H), 7.66 (d, J = 8.2 Hz, 2H). 13C{1H} NMR (126 MHz,
1
3
124.1 (q, JC,F = 271 Hz), 125.5 (q, JC,F = 3.5 Hz, 2C), 129.7 (2C),
130.1 (q, 2JC,F = 32.3 Hz), 136.4, 138.1, 139.6, 151.3, 193.3. 19F{1H}
NMR (471 MHz, CDCl3): δ −62.7.
1
CD2Cl2): δ 15.2, 22.1, 22.5, 24.5, 26.4, 124.7 (q, JC,F = 272 Hz),
3
2
(E)-1-(3,4-Dihydro-2H-pyran-6-yl)-3-(4-methoxyphenyl)-2-meth-
ylprop-2-en-1-one (21d). Prepared from 3,4-dihydro-2H-pyran (0.37
g, 0.40 mL, 4.4 mmol, 1.0 equiv), tBuLi (1.8 M in pentane, 2.7 mL,
4.9 mmol, 1.1 equiv), and (E)-3-(4-methoxyphenyl)-2-methylacry-
laldehyde (0.80 g, 4.5 mmol, 1.0 equiv) in THF (3 mL) according to
GP2. (E)-1-(3,4-Dihydro-2H-pyran-6-yl)-3-(4-methoxyphenyl)-2-
methylprop-2-en-1-ol (0.62 g, 2.4 mmol, 55%) was obtained as a
yellow oil after purification by flash column chromatography on silica
gel using cyclohexane/tert-butyl methyl ether (100/1 → 10/1) as
eluent. Rf = 0.19 (cyclohexane/tert-butyl methyl ether = 3/1). IR
125.6 (q, JC,F = 3.6 Hz, 2C), 129.7 (q, JC,F = 32 Hz), 130.0 (2C),
135.2, 138.5, 139.5, 140.5, 142.0, 200.3. 19F NMR (471 MHz,
CD2Cl2): δ −63.0.
(E)-1-(Cyclohex-1-en-1-yl)-3-(4-methoxyphenyl)-2-methylprop-
2-en-1-one (23d). Prepared from 1-bromocyclohex-1-ene (0.700 g,
4.35 mmol, 1.00 equiv) in THF (4 mL), tBuLi (1.82 M in pentane,
2.60 mL, 4.74 mmol, 1.09 equiv), and (E)-3-(4-methoxyphenyl)-2-
methylacrylaldehyde (0.840 g, 4.79 mmol, 1.10 equiv) in THF (2
mL) according to GP2. (E)-1-(Cyclohex-1-en-1-yl)-3-(4-methoxy-
phenyl)-2-methylprop-2-en-1-ol (0.272 g, 1.05 mmol, 24%) was
obtained as a yellow oil after purification by flash column
chromatography on silica gel using cyclohexane/ethyl acetate (20/1
→ 10/1) as eluent. Rf = 0.29 (cyclohexane/ethyl acetate = 90/10).
(ATR): ν 2928 (w), 2843 (w) 1673 (w), 1605 (m), 1508 (s), 1440
̃
(w), 1296 (w), 1245 (s), 1175 (s), 1059 (s), 1031 (s) cm−1. HRMS
+
(APCI, m/z): calculated for C16H21O3 [M + H]+, 261.1485; found,
261.1485. 1H NMR (500 MHz, C6D6): δ 1.38−1.46 (m, 2H), 1.76−
1.82 (m, 2H), 1.84 (d, J = 5.1 Hz, 1H), 1.97 (d, J = 1.3 Hz, 3H), 3.31
(s, 3H), 3.69 (mc, 2H), 4.56 (d, J = 4.8 Hz, 1H), 4.86 (t, J = 3.7 Hz,
1H), 6.74 (s, 1H), 6.79 (d, J = 8.8 Hz, 2H), 7.25 (d, J = 8.7 Hz, 2H).
13C{1H} NMR (126 MHz, C6D6): δ 14.4, 20.3, 22.7, 54.8, 66.3, 78.0,
96.7, 114.0 (2C), 126.8, 130.7 (2C), 130.9, 136.6, 154.5, 158.8. The
previously prepared diallyl alcohol (0.50 g, 1.9 mmol, 1.0 equiv) in
dichloromethane (50 mL) was then reacted with pyridine (2.0 mL),
GLC (HP-5): tR = 23.0 min. IR (ATR): ν 3406 (w), 2923 (w), 2833
̃
(w), 1602 (m), 1508 (s), 1439 (m), 1298 (w), 1244 (s), 1174 (s),
1031 (s), 830 (m), 804 (m) cm−1. HRMS (APCI, m/z): calculated
1
for C17H21O+ [M − OH]+, 241.1587; found, 241.1588. H NMR
(500 MHz, C6D6): δ 1.18 (s, 1H), 1.43−1.50 (m, 2H), 1.51−1.57 (m,
2H), 1.79 (d, J = 1.3 Hz, 3H), 1.82−1.89 (m, 1H), 1.96−2.00 (m,
3H), 3.33 (s, 3H), 4.33 (s, 1H), 5.81−5.83 (m, 1H), 6.64 (s, 1H),
6.80−6.83 (m, 2H), 7.22−7.25 (m, 2H). 13C{1H} NMR (126 MHz,
F
DOI: 10.1021/acs.organomet.8b00496
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
C6D6): δ 14.1, 23.1, 23.2, 24.8, 25.4, 54.8, 81.3, 114.0 (2C), 123.0,
125.8, 130.6 (2C), 131.0, 137.3, 138.5, 158.8. The previously
prepared diallyl alcohol (0.236 g, 0.910 mmol, 1.00 equiv) in
dichloromethane (20 mL) was then reacted with pyridine (0.7 mL)
and Dess−Martin periodinane (0.420 g, 1.00 mmol, 1.10 equiv)
according to GP2. The product 23d (0.131 g, 0.510 mmol, 56%) was
obtained as a white solid after purification by flash column
chromatography on silica gel using cyclohexane/ethyl acetate (30/
1) as eluent. Rf = 0.56 (cyclohexane/ethyl acetate = 90/10). Mp: 64
2H). 13C{1H} NMR (126 MHz, CDCl3): δ 12.5, 21.8, 22.6, 43.2,
48.5, 67.3, 130.6 (2C), 131.8 (2C). The analytical and spectroscopic
data are in accordance with those reported.23
6 - M e t h y l - 5 - ( 4 - ( t r i fl u o r o m e t h y l ) p h e n y l ) - 3 , 4 , 5 , 6 -
tetrahydrocyclopenta[b]pyran-7(2H)-one (22c). Prepared from
divinyl ketone 21c (24 mg, 82 μmol, 1.0 equiv) and [(C6F5)3PF]+[B-
(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %) according to GP3.
Purification of the crude product (dr(trans:cis) = 45:55) afforded
trans-22c and cis-22c (10 mg, 34 μmol, 41%, dr(trans:cis) = 44:56) as
a yellow oil after purification by flash column chromatography on
silica gel using cyclohexane/dichloromethane (100/0 → 4/1 → 1/1)
as eluent. The ratio of trans-22c to cis-22c was determined by
integration of baseline-separated signals at 3.42 and 4.09 ppm in the
1H NMR spectrum.
°C (n-pentane); GLC (HP-5): tR = 23.3 min. IR (ATR): ν 2936 (w),
̃
1598 (s), 1509 (s), 1438 (m), 1302 (s), 1246 (s), 1174 (s), 1124
(m), 1026 (s), 1003 (s), 835 (s), 803 (s) cm−1. HRMS (ESI, m/z):
+
1
calculated for C17H21O2 [M + H]+, 257.1536; found, 257.1543. H
NMR (500 MHz, CD2Cl2): δ 1.63−1.68 (m, 2H), 1.68−1.74 (m,
2H), 2.09 (d, J = 1.5 Hz, 3H), 2.22−2.26 (m, 2H), 2.28−2.32 (m,
2H), 3.83 (s, 3H), 6.52−6.54 (m, 1H), 6.93 (mc, 2H), 7.05 (mc, 1H),
7.39 (mc, 2H). 13C{1H} NMR (126 MHz, CD2Cl2): δ 14.9, 22.2,
22.6, 25.0, 26.2, 55.7, 114.2 (2C), 129.2, 131.6 (2C), 135.3, 138.4,
138.8, 139.8, 160.0, 201.0.
Selected Analytical Data for trans-22c. Rf = 0.22 (cyclohexane/
tert-butyl methyl ether = 3/1). GLC (HP-5): tR = 20.9 min. HRMS
+
(ESI, m/z): calculated for C16H16F3O2 [M + H]+, 297.1097; found,
1
297.1096. H NMR (500 MHz, CDCl3): δ 1.28 (d, J = 7.4 Hz, 3H),
1.92−2.03 (m, 2H), 2.07−2.12 (m, 2H), 2.21−2.25 (m, 1H), 3.42
(mc, 1H), 4.15−4.19 (m, 2H), 7.25−7.27 (m, 2H), 7.60 (d, J = 8.1
Hz, 2H). 13C{1H} NMR (126 MHz, CDCl3): δ 15.0, 21.6, 22.1, 49.3,
53.1, 67.1, 126.1−126.2 (m, 2C), 127.9 (2C), 144.2, 145.6, 151.3,
202.0. 19F NMR (471 MHz, CDCl3): δ −62.5.
6-Methyl-5-phenyl-3,4,5,6-tetrahydrocyclopenta[b]pyran-7(2H)-
one (22a). Prepared from divinyl ketone 21a (37 mg, 0.16 mmol, 1.0
equiv) and [(C6F5)3PF]+[B(C6F5)4]− (6; 6.2 mg, 5.0 μmol, 3.0 mol
%) according to GP3. Purification of the crude product (dr(trans:cis)
= 63:37) afforded trans-22a and cis-22a (8.7 mg, 38 μmol, 23%,
dr(trans:cis) = 65:35) as a yellow oil after purification by flash column
chromatography on silica gel using cyclohexane/dichloromethane
(80/20 → 50/50) as eluent. The ratio of trans-22a to cis-22a was
determined by integration of baseline-separated signals at 3.34 and
Selected Analytical Data for cis-22c. Rf = 0.16 (cyclohexane/tert-
1
butyl methyl ether = 3/1). GLC (HP-5): tR = 20.4 min. H NMR
(500 MHz, CDCl3): δ 0.68 (d, J = 7.7 Hz, 3H), 1.92−2.03 (m, 2H),
2.14−2.19 (m, 2H), 2.77−2.83 (m, 1H), 4.09 (d, J = 6.7 Hz, 1H),
4.14−4.19 (m, 1H), 4.21−4.26 (m, 1H), 7.16 (d, J = 7.7 Hz, 2H),
7.58 (d, J = 8.2 Hz, 2H). 13C{1H} NMR (126 MHz, CDCl3): δ 12.5,
21.7, 22.6, 43.2, 48.8, 67.3, 124.2 (q, 1JC,F = 272 Hz, -CF3), 125.6 (mc,
2C), 129.3 (2C), 143.1, 143.8, 152.1, 202.3. 19F NMR (471 MHz,
CDCl3): δ −62.5.
1
4.02 ppm in the H NMR spectrum.
Analytical Data for trans-22a. Rf = 0.45 (cyclohexane/tert-butyl
methyl ether = 1/1). GLC (HP-5): tR = 19.1 min (cis-22a), tR+= 20.7
min (trans-22a). HRMS (ESI, m/z): calculated for C15H17O2 [M +
1
H]+, 229.1223; found, 229.1220. H NMR (500 MHz, CDCl3): δ
5-(4-Methoxyphenyl)-6-methyl-3,4,5,6-tetrahydrocyclopenta[b]-
pyran-7(2H)-one (22d). Prepared from divinyl ketone 21d (21 mg,
82 μmol, 1.0 equiv) and [(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5
μmol, 3.0 mol %) according to GP3. Purification of the crude product
(dr(trans:cis) = 35:65) afforded trans-22d and cis-22d (6.4 mg, 25
μmol, 30%, dr(trans:cis) = 38:62) as a yellow oil after purification by
flash column chromatography on silica gel using cyclohexane/
dichloromethane (100/0 → 4/1 → 1/1) as eluent. The ratio of
trans-22d to cis-22d was determined by integration of baseline-
1.27 (d, J = 7.5 Hz, 3H), 1.90−1.98 (m, 2H), 2.08−2.12 (m, 2H),
2.22−2.29 (m, 1H), 3.34 (mc, 1H), 4.16 (mc, 2H), 7.12−7.15 (m,
2H), 7.27−7.29 (m, 1H), 7.32−7.36 (m, 2H). 13C{1H} NMR (126
MHz, CDCl3): δ 15.0, 21.7, 22.2, 49.5, 53.4, 67.1, 127.3, 127.5 (2C),
129.1 (2C), 141.4, 145.4, 150.8, 202.7. The analytical and
spectroscopic data are in accordance with those reported.31
Selected Analytical Data for cis-22a. Rf = 0.37 (cyclohexane/tert-
butyl methyl ether = 1/1). 1H NMR (500 MHz, CDCl3): δ 0.69 (d, J
= 7.6 Hz, 3H), 1.95−2.03 (m, 2H), 2.17−2.21 (m, 2H), 2.72−2.79
(m, 1H), 4.00−4.03 (m, 1H), 4.17−4.25 (m, 2H), 7.00−7.04 (m,
2H). 13C{1H} NMR (126 MHz, CDCl3): δ 12.4, 21.8, 22.7, 43.4,
49.0, 67.2, 127.3, 128.6, 138.8, 144.9, 203.0. The analytical and
spectroscopic data are in accordance with those reported.23
1
separated signals at 3.29 and 3.96 ppm in the H NMR spectrum.
Analytical Data for trans-22d. Rf = 0.52 (cyclohexane/tert-butyl
methyl ether = 1/1). GLC (HP-5): tR = 23.8 min. HRMS (ESI, m/z):
+
1
calculated for C16H19O3 [M + H]+, 259.1329; found, 259.1328. H
NMR (500 MHz, CDCl3): δ 1.25 (d, J = 7.4 Hz, 3H), 1.89−2.02 (m,
2H), 2.09 (mc, 2H), 2.20−2.24 (m, 1H), 3.29 (mc, 1H), 3.80 (s, 3H),
4.13−4.23 (m, 2H), 6.86−6.89 (m, 2H), 7.03−7.06 (m, 2H).
13C{1H} NMR (126 MHz, CDCl3): δ 15.0, 21.8, 22.2, 49.6, 52.6,
55.5, 67.0, 114.5 (2C), 128.5 (2C), 133.2, 145.6, 150.7, 158.9, 202.8.
Analytical Data for cis-22d. Rf = 0.42 (cyclohexane/tert-butyl
5-(4-Bromophenyl)-6-methyl-3,4,5,6-tetrahydrocyclopenta[b]-
pyran-7(2H)-one (22b). Prepared from divinyl ketone 21b (25 mg,
82 μmol, 1.0 equiv) and [(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5
μmol, 3.0 mol %) according to GP3. Purification of the crude product
(dr(trans:cis) = 57:43) afforded trans-22b (4.5 mg, 15 μmol, 18%,
dr(trans:cis) = 96:4) as a colorless oil and cis-22b (4.2 mg, 14 μmol,
17%, dr(trans:cis) = 17:83) as a colorless oil after purification by flash
column chromatography on silica gel using cyclohexane/tert-butyl
methyl ether (20/1 → 5/1) as eluent. The ratio of trans-22b to cis-
22b was determined by integration of baseline-separated signals at
1
methyl ether = 1/1). GLC (HP-5): tR = 23.4 min. H NMR (500
MHz, CDCl3): δ 0.69 (d, J = 7.7 Hz, 3H), 1.89−2.02 (m, 2H), 2.16−
2.19 (m, 2H), 2.72 (mc, 1H), 3.80 (s, 3H), 3.96 (mc, 1H), 4.13−4.23
(m, 2H), 6.83−6.86 (m, 2H), 6.94 (mc, 2H). 13C{1H} NMR (126
MHz, CDCl3): δ 12.5, 21.9, 22.6, 43.6, 48.3, 55.4, 67.2, 114.5 (2C),
129.9 (2C), 130.7, 145.2, 151.6, 158.8, 203.2. The analytical and
spectroscopic data are in accordance with those reported.32
1
3.31 and 3.98 ppm in the H NMR spectrum.
Analytical Data for trans-22b. Rf = 0.39 (cyclohexane/tert-butyl
methyl ether = 1/1). GLC (HP-5): tR = 23.9 min. HRMS (ESI, m/z):
calculated for C15H16BrO2+ [M + H]+, 307.0328; found, 307.0326. 1H
NMR (500 MHz, CDCl3): δ 1.26 (d, J = 7.4 Hz, 3H), 1.91−1.99 (m,
2H), 2.06−2.11 (m, 2H), 2.17−2.23 (m, 1H), 3.31 (mc, 1H), 4.15
(mc, 2H), 7.01 (mc, 2H), 7.47 (mc, 2H). 13C{1H} NMR (126 MHz,
CDCl3): δ 15.0, 21.7, 22.1, 49.4, 52.8, 67.1, 121.2, 129.2 (2C), 132.3
(2C), 140.4, 144.5, 151.1, 202.2.
3-(Furan-2-yl)-2-methyl-2,3,3a,4,5,6-hexahydro-1H-inden-1-one
(22e). Prepared from divinyl ketone 21e (18 mg, 82 μmol, 1.0 equiv)
and [(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %)
according to GP3. Purification of the crude product (dr(trans:cis) =
55:45) afforded trans-22e and cis-22e (4.6 mg, 21 μmol, 26%,
dr(trans:cis) = 54:46) as an orange oil after purification by flash
column chromatography on silica gel using cyclohexane/dichloro-
methane (100/0 → 4/1 → 1/1) as eluent. The ratio of trans-22e to
cis-22e was determined by integration of baseline-separated signals at
Selected Analytical Data for cis-22b. Rf = 0.29 (cyclohexane/tert-
1
butyl methyl ether = 1/1). GLC (HP-5): tR = 24.4 min. H NMR
1
(500 MHz, CDCl3): δ 0.69 (d, J = 7.6 Hz, 3H), 1.90−2.05 (m, 2H),
2.12−2.20 (m, 2H), 2.75 (mc, 1H), 3.98 (mc, 1H), 4.13−4.17 (m,
1H), 4.19−4.25 (m, 1H), 6.91 (d, J = 8.0 Hz, 2H), 7.43−7.45 (m,
1.27 and 0.84 ppm in the H NMR spectrum.
Analytical Data for trans-22e. Rf = 0.18 (cyclohexane/tert-butyl
methyl ether = 3/1). GLC (HP-5): tR = 18.7 min. HRMS (ESI, m/z):
G
DOI: 10.1021/acs.organomet.8b00496
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+
1
calculated for C13H15O3 [M + H]+, 219.1016; found, 219.1015. H
NMR (500 MHz, CDCl3): δ 1.27 (d, J = 7.5 Hz, 3H), 1.94−2.00 (m,
2H), 2.20−2.22 (m, 2H), 2.46−2.51 (m, 1H), 3.50 (mc, 1H), 4.13−
4.15 (m, 2H), 6.13 (d, J = 3.3 Hz, 1H), 6.31−6.33 (m, 1H), 7.34−
7.35 (m, 1H). 13C{1H} NMR (126 MHz, CDCl3): δ 15.0, 21.7, 22.4,
45.6, 46.4, 67.0, 106.4, 110.5, 142.3, 142.7, 150.6, 153.8, 201.7. The
analytical and spectroscopic data are in accordance with those
reported.32
(500 MHz, CDCl3): δ 1.90 (d, J = 1.6 Hz, 3H), 2.58−2.65 (m, 1H),
3.30−3.36 (m, 1H), 7.39−7.49 (m, 5H). 13C{1H} NMR (126 MHz,
CDCl3): δ 9.8, 21.3, 21.5, 23.0, 28.4, 41.6, 45.7, 127.8 (2C), 128.7
(2C), 129.1.
(2S,3R,3aR)-3-(4-Bromophenyl)-2-methyl-2,3,3a,4,5,6-hexahy-
dro-1H-inden-1-one (trans-24b) and (3aS,7aR)-3-(4-Bromophen-
yl)-2-methyl-3a,4,5,6,7,7a-hexahydro-1H-inden-1-one (25b). Pre-
pared from divinyl ketone 23b (25 mg, 82 μmol, 1.0 equiv) and
[(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %) according
to GP3. Purification of the crude product (trans-23b:24b = 83:17)
afforded trans-24b and 25b (19.3 mg, 63.0 μmol, 77%, trans-24b:25b
= 83:17) as a colorless oil after purification by flash column
chromatography on silica gel using cyclohexane/tert-butyl methyl
ether (20/1) as eluent. The ratio of trans-24b to 25b was determined
by integration of baseline-separated signals at 6.80 and 3.28 ppm in
Analytical Data for cis-22e. Rf = 0.11 (cyclohexane/tert-butyl
methyl ether = 3/1). GLC (HP-5): tR = 19.1 min. H NMR (500
MHz, CDCl3): δ 0.84 (d, J = 7.6 Hz, 3H), 1.94−2.00 (m, 2H), 2.17−
2.33 (m, 2H), 2.68−2.74 (m, 1H), 4.10−4.12 (m, 1H), 4.12−4.23
(m, 2H), 6.06 (mc, 1H), 6.31−6.33 (m, 1H), 7.34−7.35 (m, 1H).
13C{1H} NMR (126 MHz, CDCl3): δ 11.9, 21.8, 22.7, 42.7, 43.4,
67.2, 108.2, 110.3, 142.1, 142.2, 151.5, 152.8, 202.3. The analytical
and spectroscopic data are in accordance with those reported.23
6-Methyl-5-(thiophen-2-yl)-3,4,5,6-tetrahydrocyclopenta[b]-
pyran-7(2H)-one (22f). Prepared from divinyl ketone 21f (19 mg, 82
μmol, 1.0 equiv) and [(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol,
3.0 mol %) according to GP3. Purification of the crude product
(dr(trans:cis) = 51:49) afforded trans-22f and cis-22f (5.3 mg, 23
μmol, 28%, dr(trans:cis) = 46:54) as a yellow oil after purification by
flash column chromatography on silica gel using cyclohexane/
dichloromethane (100/0 → 4/1 → 1/1) as eluent. The ratio of
trans-22f to cis-22f was determined by integration of baseline-
1
1
the H NMR spectrum.
Analytical Data for trans-24b. Rf = 0.58 (cyclohexane/tert-butyl
methyl ether = 3/1). GLC (HP-5): tR = 23.1 min. HRMS (ESI, m/z):
calculated for C16H18BrO+ [M + H]+, 305.0536; found, 305.0536. 1H
NMR (500 MHz, CDCl3): δ 1.00−1.08 (m, 1H), 1.02 (d, J = 6.8 Hz,
3H), 1.45−1.54 (m, 1H), 1.83−1.94 (m, 2H), 2.15−2.26 (m, 2H),
2.31−2.37 (m, 1H), 2.37−2.43 (m, 1H), 2.53−2.61 (m, 1H), 6.80
(mc, 1H), 7.12−7.15 (m, 2H), 7.46−7.49 (m, 2H). 13C{1H} NMR
(126 MHz, CDCl3): δ 12.1, 21.8, 25.7, 26.9, 44.2, 50.9, 56.2, 120.8,
129.3 (2C), 131.9 (2C), 133.4, 140.2 (2C), 205.5. The analytical and
spectroscopic data are in accordance with those reported.23
1
separated signals at 1.29 and 0.84 ppm in the H NMR spectrum.
Selected Analytical Data for trans-22f. Rf = 0.35 (cyclohexane/
tert-butyl methyl ether = 3/1). GLC (HP-5): tR = 20.6 min. HRMS
(ESI, m/z): calculated for C13H15O2S+ [M + H]+, 235.0787; found,
Selected Analytical Data for 25b. Rf = 0.42 (cyclohexane/tert-
butyl methyl ether = 3/1). GLC (HP-5): tR = 23.4 min. H NMR
1
(500 MHz, CDCl3): δ 1.87 (d, J = 1.6 Hz, 3H), 3.25−3.31 (m, 1H).
1
13C{1H} NMR (126 MHz, CDCl3): δ 9.8, 21.3, 21.5, 22.9, 28.4, 41.4,
235.0786. H NMR (500 MHz, CDCl3): δ 1.29 (d, J = 7.4 Hz, 3H),
1.93−2.01 (m, 2H), 2.12−2.37 (m, 2H), 2.37−2.42 (m, 1H), 3.68
(mc, 1H), 4.14−4.24 (m, 2H), 6.88 (mc, 1H), 6.95−6.99 (m, 1H),
7.18−7.22 (m, 1H). 13C{1H} NMR (126 MHz, CDCl3): δ 15.0, 21.7,
22.2, 48.3, 49.9, 67.3, 124.5, 124.9, 127.2, 144.9, 201.7.
45.7, 129.4 (2C), 132.0 (2C).
(2S,3R,3aR)-2-Methyl-3-(4-(trifluoromethyl)phenyl)-2,3,3a,4,5,6-
hexahydro-1H-inden-1-one (trans-24c) and (3aS,7aR)-2-Methyl-3-
(4-(trifluoromethyl)phenyl)-3a,4,5,6,7,7a-hexahydro-1H-inden-1-
one (25c). Prepared from divinyl ketone 23c (24 mg, 82 μmol, 1.0
equiv) and [(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol
%) according to GP3. Purification of the crude product (trans-
24c:25c = 88:12) afforded a mixture of trans-24c and 25c (19.9 mg,
68 μmol, 82%, trans-24c:25c = 88:12) as a colorless oil after
purification by flash column chromatography on silica gel using
cyclohexane/tert-butyl methyl ether (20/1) as eluent. The ratio of
trans-24c to 25c was determined by integration of baseline-separated
Selected Analytical Data for cis-22f. Rf = 0.26 (cyclohexane/tert-
1
butyl methyl ether = 3/1). GLC (HP-5): tR = 21.1 min. H NMR
(500 MHz, CDCl3): δ 0.84 (d, J = 7.6 Hz, 3H), 1.93−2.01 (m, 2H),
2.12−2.37 (m, 2H), 2.74 (mc, 1H), 4.14−4.24 (m, 2H), 4.31 (d, J =
6.6 Hz, 1H), 6.78 (mc, 1H), 6.95−6.99 (m, 1H), 7.18−7.22 (m, 1H).
13C{1H} NMR (126 MHz, CDCl3): δ 11.9, 21.8, 22.7, 43.9, 44.1,
67.1, 124.5, 126.4, 127.1, 142.7, 202.2. The analytical and
spectroscopic data are in accordance with those reported.23
(2S,3R,3aR)-2-Methyl-3-phenyl-2,3,3a,4,5,6-hexahydro-1H-
inden-1-one (trans-24a) and (3aS,7aR)-2-Methyl-3-phenyl-
3a,4,5,6,7,7a-hexahydro-1H-inden-1-one (25a). Prepared from
divinyl ketone 23a (19 mg, 82 μmol, 1.0 equiv) and [(C6F5)3PF]+[B-
(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %) according to GP3.
Purification of the crude product (trans-24a:25a = 85:15) afforded
trans-24a (8.3 mg, 37 μmol, 45%) as a colorless oil and a product
mixture (9.5 mg, 42 μmol, 51%, trans-24a:25a = 54:46) as a colorless
oil after purification by flash column chromatography on silica gel
using cyclohexane/dichloromethane (100/0 → 4/1 → 1/1) as eluent.
The ratio of trans-24a to 25a was determined by integration of
baseline-separated signals at 6.80 and 3.33 ppm in the 1H NMR
spectrum.
1
signals at 6.83 and 3.32 ppm in the H NMR spectrum.
Analytical Data for trans-24c. Rf = 0.57 (cyclohexane/tert-butyl
methyl ether = 3/1). GLC (HP-5): tR = 19.6 min. HRMS (ESI, m/z):
calculated for C17H18F3O+ [M + H]+, 295.1304; found, 295.1301. 1H
NMR (500 MHz, CDCl3): δ 1.04 (d, J = 6.7 Hz, 3H), 1.05−1.11 (m,
1H), 1.46−1.56 (m, 1H), 1.84−1.94 (m, 2H), 2.16−2.25 (m, 1H),
2.33−2.39 (m, 2H), 2.43−2.50 (m, 1H), 2.59−2.67 (m, 1H), 6.83
(mc, 1H), 7.38 (d, J = 8.1 Hz, 2H), 7.62 (d, J = 8.2 Hz, 2H). 13C{1H}
NMR (126 MHz, CDCl3): δ 12.2, 21.8, 25.7, 27.0, 44.2, 50.9, 56.5,
1
3
124.3 (q, JC,F = 272 Hz, -CF3), 125.8 (q, JC,F = 3.7 Hz, 2C), 128.0
2
(2C), 129.5 (q, JC,F = 32 Hz), 133.6, 140.0, 145.4, 205.2. 19F NMR
(471 MHz, CDCl3): δ −62.5.
Selected Analytical Data for 25c. Rf = 0.57 (cyclohexane/tert-
butyl methyl ether = 3/1). GLC (HP-5): tR = 19.7 min. H NMR
1
Analytical Data for trans-24a. Rf = 0.63 (cyclohexane/tert-butyl
̃
methyl ether = 3/1). GLC (HP-5): tR = 19.7 min. IR (ATR): ν 2927
(500 MHz, CDCl3): δ 1.88 (d, J = 1.7 Hz, 3H), 3.29−3.35 (m, 1H),
7.52 (mc, 2H), 7.71 (mc, 2H). 13C{1H} NMR (126 MHz, CDCl3): δ
9.7, 21.3, 21.4, 22.9, 28.2, 41.7, 45.8. 19F NMR (471 MHz, CDCl3): δ
−62.8.
(2S,3R,3aR)-3-(4-Methoxyphenyl)-2-methyl-2,3,3a,4,5,6-hexahy-
dro-1H-inden-1-one (trans-24d) and (3aS,7aR)-3-(4-Methoxyphen-
yl)-2-methyl-3a,4,5,6,7,7a-hexahydro-1H-inden-1-one (25d). Pre-
pared from divinyl ketone 23d (21 mg, 82 μmol, 1.0 equiv) and
[(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %) according
to GP3. Purification of the crude product (trans-24d:25d = 84:16)
afforded trans-24d (8.6 mg, 34 μmol, 41%) as a yellow oil and a
product mixture of trans-24d and 25d (3.9 mg, 15 μmol, 18%, trans-
24d:25d = 55:45) as a yellow oil after purification by flash column
chromatography on silica gel using cyclohexane/tert-butyl methyl
(w), 2868 (w), 1715 (s), 1650 (s), 1450 (m), 1174 (m), 922 (m),
759 (m), 698 (s) cm−1. HRMS (ESI, m/z): calculated for C16H19O+
[M + H]+, 227.1430; found, 227.1428. 1H NMR (500 MHz, CDCl3):
δ 1.02−1.10 (m, 1H), 1.04 (d, J = 6.8 Hz, 3H), 1.50 (mc, 1H), 1.83−
1.88 (m, 1H), 1.95 (mc, 1H), 2.15−2.25 (m, 1H), 2.28 (mc, 1H),
2.31−2.38 (m, 1H), 2.46 (mc, 1H), 2.58−2.65 (m, 1H), 6.80 (mc,
1H), 7.25−7.26 (m, 1H), 7.27−7.29 (m, 2H), 7.34−7.38 (m, 2H).
13C{1H} NMR (126 MHz, CDCl3): δ 12.2, 21.9, 25.8, 27.1, 44.3,
51.0, 56.7, 127.1, 127.6 (2C), 128.8 (2C), 133.0, 140.6, 141.2, 206.1.
The analytical and spectroscopic data are in accordance with those
reported.23
Selected Analytical Data for 25a. Rf = 0.57 (cyclohexane/tert-
1
butyl methyl ether = 3/1). GLC (HP-5): tR = 20.1 min. H NMR
H
DOI: 10.1021/acs.organomet.8b00496
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
ether (20/1) as eluent. The ratio of trans-24d to 25d was determined
found 233.0992. 1H NMR (500 MHz, CDCl3): δ 1.05−1.12 (m, 1H),
1.14 (d, J = 6.8 Hz, 3H), 1.50−1.56 (m, 1H), 1.87−1.92 (m, 1H),
2.11−2.18 (m, 1H), 2.18−2.25 (m, 1H), 2.32−2.38 (m, 1H), 2.38−
2.44 (m, 1H), 2.56−2.65 (m, 2H), 6.80 (mc, 1H), 6.92 (mc, 1H),
6.99−7.00 (m, 1H), 7.22 (mc, 1H). 13C{1H} NMR (126 MHz,
CDCl3): δ 12.4, 21.8, 25.8, 27.2, 45.3, 51.6, 52.3, 123.6, 124.5, 127.1,
133.5, 140.1, 145.4, 205.2. The analytical and spectroscopic data are
in accordance with those reported.23
by integration of baseline-separated signals at 6.79 and 3.32 ppm in
1
the H NMR spectrum.
Analytical Data for trans-24d. Rf = 0.58 (cyclohexane/tert-butyl
methyl ether = 3/1). GLC (HP-5): tR = 22.5 min. IR (ATR): ν 2928
̃
(w), 2868 (w), 1715 (s), 1651 (s), 1510 (s), 1248 (s), 1174 (m),
1032 (m), 923 (m), 826 (m), 729 (s) cm−1. HRMS (ESI, m/z):
+
1
calculated for C17H21O2 [M + H]+, 257.1536; found 257.1534. H
NMR (500 MHz, CDCl3): δ 1.00−1.08 (m, 1H), 1.03 (d, J = 6.8 Hz,
3H), 1.49 (mc, 1H), 1.83−1.88 (m, 1H), 1.92−1.97 (m, 1H), 2.15−
2.24 (m, 2H), 2.30−2.37 (m, 1H), 2.37−2.43 (m, 1H), 2.52−2.60
(m, 1H), 3.82 (s, 3H), 6.79 (mc, 1H), 6.89−6.91 (m, 2H), 7.16−7.19
(m, 2H). 13C{1H} NMR (126 MHz, CDCl3): δ 12.1, 21.9, 25.8, 27.0,
44.4, 51.1, 55.4, 55.9, 114.2 (2C), 128.5 (2C), 132.9, 133.1, 140.7,
158.7, 206.3.
Analytical Data for 25f. Rf = 0.30 (cyclohexane/tert-butyl methyl
1
ether = 10/1). GLC (HP-5): tR = 21.0 min. H NMR (500 MHz,
CDCl3): δ 1.02−1.06 (m, 1H), 1.15−1.22 (m, 1H), 1.27−1.38 (m,
2H), 1.63−1.71 (m, 2H), 2.05 (d, J = 1.1 Hz, 3H), 2.23−2.30 (m,
2H), 2.58−2.61 (m, 1H), 3.32 (mc, 1H), 7.19 (mc, 1H), 7.46 (mc,
1H), 7.58 (mc, 1H). 13C{1H} NMR (126 MHz, CDCl3): δ 10.4, 22.4,
22.8, 22.9, 32.0, 41.6, 46.6, 127.8, 128.6, 129.5, 131.6, 138.9, 162.4,
209.4.
Ethyl trans-2,4-Dimethyl-5-oxo-3-phenylcyclopent-3-ene-1-car-
boxylate (trans-27). Prepared from divinyl ketone 26 (21 mg, 82
μmol, 1.0 equiv) and [(C6F5)3PF]+[B(C6F5)4]− (6; 3.1 mg, 2.5 μmol,
3.0 mol %) according to GP3. The product trans-27 (12.7 mg, 49.0
μmol, 60%) was obtained as a colorless oil after purification by flash
column chromatography on silica gel using cyclohexane/dichloro-
methane (100/0 → 4/1) as eluent. Rf = 0.48 (cyclohexane/tert-butyl
methyl ether = 3/1). GLC (HP-5): tR = 19.7 min. HRMS (ESI, m/z):
Selected Analytical Data for 25d. Rf = 0.50 (cyclohexane/tert-
1
butyl methyl ether = 3/1). GLC (HP-5): tR = 23.1 min. H NMR
(500 MHz, CDCl3): δ 1.93 (d, J = 1.5 Hz, 3H), 2.56−2.60 (m, 1H),
3.28−3.35 (m, 1H), 3.86 (s, 3H), 6.96−7.00 (m, 2H), 7.43−7.46 (m,
2H). 13C{1H} NMR (126 MHz, CDCl3): δ 10.1, 21.4, 21.7, 23.0,
28.9, 41.2, 45.7, 55.5, 114.2 (2C), 129.6 (2C).
(2S,3R,3aR)-3-(Furan-2-yl)-2-methyl-2,3,3a,4,5,6-hexahydro-1H-
inden-1-one (trans-24e) and (3aS,7aR)-3-(Furan-2-yl)-2-methyl-
3a,4,5,6,7,7a-hexahydro-1H-inden-1-one (25e). Prepared from
divinyl ketone 23e (18 mg, 82 μmol, 1.0 equiv) and [(C6F5)3PF]+[B-
(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %) according to GP3.
Purification of the crude product (trans-24e:25e = 53:47) afforded
trans-24e (4.1 mg, 19 μmol, 23%, trans-24e:25e = 96:4) as a yellow
oil and a product mixture of trans-24e and 25e (7.1 mg, 33 μmol,
40%, trans-24e:25e = 26:74) as a yellow oil after purification by flash
column chromatography on silica gel using cyclohexane/tert-butyl
methyl ether (30/1) as eluent. The ratio of trans-24e to 25e was
determined by integration of baseline-separated signals at 7.38 and
+
1
calculated for C16H19O3 [M + H]+, 259.1329; found 259.1329. H
NMR (500 MHz, CDCl3): δ 1.13 (d, J = 7.3 Hz, 3H), 1.33 (t, J = 7.2
Hz, 3H), 1.86 (d, J = 2.0 Hz, 3H), 3.14 (d, J = 2.7 Hz, 1H), 3.66−
3.71 (m, 1H), 4.26 (mc, 2H), 7.39−7.44 (m, 3H), 7.45−7.49 (m,
2H). 13C{1H} NMR (126 MHz, CDCl3): δ 9.9, 14.4, 19.2, 40.3, 59.9,
61.7, 128.0 (2C), 128.8 (2C), 129.6, 134.7, 134.8, 169.4, 172.3, 201.8.
The analytical and spectroscopic data are in accordance with those
reported.25
1
7.61 ppm in the H NMR spectrum.
ASSOCIATED CONTENT
■
Analytical Data for trans-24e. Rf = 0.65 (cyclohexane/tert-butyl
S
* Supporting Information
methyl ether = 3/1). GLC (HP-5): tR = 17.3 min. HRMS (ESI, m/z):
+
1
calculated for C14H17O2 [M + H]+, 217.1223; found 217.1227. H
NMR (500 MHz, CDCl3): δ 1.06−1.12 (m, 1H), 1.14 (d, J = 6.7 Hz,
3H), 1.49−1.56 (m, 1H), 1.86−1.93 (m, 1H), 2.11−2.26 (m, 2H),
2.30−2.38 (m, 1H), 2.39−2.45 (m, 1H), 2.47−2.55 (m, 1H), 2.65−
2.73 (m, 1H), 6.14 (d, J = 3.1 Hz, 1H), 6.35 (mc, 1H), 6.79 (mc, 1H),
7.38 (mc, 1H). 13C{1H} NMR (126 MHz, CDCl3): δ 12.7, 21.8, 25.7,
27.5, 41.9, 48.9, 49.3, 105.8, 110.3, 133.5, 140.1, 141.8, 155.4, 205.7.
The analytical and spectroscopic data are in accordance with those
reported.23
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.8b00496.
Overview of screened catalysts and figures giving NMR
spectra of compounds synthesized in this paper (PDF)
AUTHOR INFORMATION
■
Analytical Data for 25e. Rf = 0.58 (cyclohexane/tert-butyl methyl
1
Corresponding Authors
ether = 3/1). GLC (HP-5): tR = 18.9 min. H NMR (500 MHz,
*E-mail for D.W.S.: douglas.stephan@utoronto.ca.
*E-mail for M.O.: martin.oestreich@tu-berlin.de.
CDCl3): δ 0.98−1.07 (m, 1H), 1.15−1.22 (m, 1H), 1.28−1.38 (m,
1H), 1.54−1.63 (m, 2H), 1.63−1.71 (m, 1H), 2.04 (d, J = 0.9 Hz,
3H), 2.18−2.30 (m, 2H), 2.51−2.56 (m, 1H), 3.23−3.29 (m, 1H),
6.56 (mc, 1H), 6.79 (d, J = 3.5 Hz, 1H), 7.61 (mc, 1H). 13C{1H}
NMR (126 MHz, CDCl3): δ 9.9, 22.2, 22.8 (2C), 31.7, 39.3, 46.1,
112.3, 113.8, 131.2, 144.6, 151.7, 157.6, 209.7.
ORCID
Maria Vogler: 0000-0002-4113-7391
̈
Lars Susse: 0000-0002-4894-1198
James H. W. LaFortune: 0000-0003-4217-1038
Douglas W. Stephan: 0000-0001-8140-8355
Martin Oestreich: 0000-0002-1487-9218
(2S,3R,3aR)-2-Methyl-3-(thiophen-2-yl)-2,3,3a,4,5,6-hexahydro-
1H-inden-1-one (trans-24f) and (3aS,7aR)-2-methyl-3-(thiophen-
2-yl)-3a,4,5,6,7,7a-hexahydro-1H-inden-1-one (25f). Prepared from
divinyl ketone 23f (19 mg, 82 μmol, 1.0 equiv) and [(C6F5)3PF]+[B-
(C6F5)4]− (6; 3.1 mg, 2.5 μmol, 3.0 mol %) according to GP3.
Purification of the crude product (trans-24f:25f = 64:36) afforded
trans-24f (4.6 mg, 20 μmol, 24%) as a yellow oil and a product
mixture of trans-24f and 25f (10.7 mg, 46.0 μmol, 56%, trans-24f:25f
= 49:51) as a yellow oil after purification by flash column
chromatography on silica gel using cyclohexane/tert-butyl methyl
ether (30/1) as eluent. The ratio of trans-24f to 25f was determined
by integration of baseline-separated signals at 6.80 and 3.32 ppm in
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
M.V. and L.S. were supported through an Einstein Visiting
Fellowship of the Einstein Foundation Berlin to D.W.S.
(2016−2019). D.W.S. and M.O. thank the Einstein Founda-
tion Berlin for generous funding. D.W.S. acknowledges the
support of the NSERC of Canada and is grateful for the award
of a Canada Research Chair. We are grateful to Mara Jensen
(TU Berlin) for her experimental contributions.
1
the H NMR spectrum.
Analytical Data for trans-24f. Rf = 0.37 (cyclohexane/tert-butyl
methyl ether = 10/1). GLC (HP-5): tR = 19.7 min. IR (ATR): ν
(w), 2865 (w), 1715 (s), 1651 (s), 1175 (w), 924 (m), 692 (s) cm−1
HRMS (ESI, m/z): calculated for C14H17OS+ [M + H]+, 233.0995;
̃
2927
.
I
DOI: 10.1021/acs.organomet.8b00496
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Article
(17) [Et3Si(toluene)]+[B(C6F5)4]− used in the final step of the
preparation of 6 is able to catalyze the model Diels−Alder reaction
and was rigorously removed by several washings with CH2Cl2. For
further related work, see: Hara, K.; Akiyama, R.; Sawamura, M. Strong
Counteranion Effects on the Catalytic Activity of Cationic Silicon
Lewis Acids in Mukaiyama Aldol and Diels−Alder Reactions. Org.
Lett. 2005, 7, 5621−5623.
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