An efficient approach to gem-difluorocyclopropylstannanes via highly regio- and stereoselective hydrostannylation of gem-difluorocyclopropenes and their unique ring-opening reaction to afford β-fluoroallylic alcohols

Article abstract of DOI:10.1039/c5ob00046g

Treatment of various gem-difluorocyclopropenes with 1.2 equiv. of n-Bu₃SnH in the presence of 20 mol% of Et₃B at 80 °C for 4 h led to the quantitative formation of the hydrostannylated products in a highly regio- and trans-selective manner. Additionally, the prepared trans-gem-difluorocyclopropylstannanes were treated with 1.5 equiv. of MeLi in THF at -78°C for 5 min, followed by quenching the reaction with various agents, such as H₂O, alcohols, carboxylic acids, and tosylamide, to give the corresponding β-fluoroallylic alcohols, ethers, esters, and amides respectively with exclusive Z selectivity in acceptable yields.

Full text of DOI:10.1039/c5ob00046g

Organic &
Biomolecular Chemistry
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PAPER
An efficient approach to gem-difluoro-
cyclopropylstannanes via highly regio- and
stereoselective hydrostannylation of
gem-difluorocyclopropenes and their unique
ring-opening reaction to afford β-fluoroallylic
alcohols†
Cite this: Org. Biomol. Chem., 2015,
13, 3721
T. Nihei, T. Hoshino and T. Konno*
Treatment of various gem-difluorocyclopropenes with 1.2 equiv. of n-Bu3SnH in the presence of 20 mol% of
Et3B at 80 °C for 4 h led to the quantitative formation of the hydrostannylated products in a highly regio-
and trans-selective manner. Additionally, the prepared trans-gem-difluorocyclopropylstannanes were
treated with 1.5 equiv. of MeLi in THF at −78 °C for 5 min, followed by quenching the reaction with
various agents, such as H2O, alcohols, carboxylic acids, and tosylamide, to give the corresponding
β-fluoroallylic alcohols, ethers, esters, and amides respectively with exclusive Z selectivity in acceptable
yields.
Received 9th January 2015,
Accepted 6th February 2015
DOI: 10.1039/c5ob00046g
www.rsc.org/obc
Introduction
Cyclopropanes are the smallest saturated cycloalkanes and one
of the most important synthetic units.1 The origin of their use
in synthetic organic chemistry may be ascribed to the very
unique structural features of cyclopropanes: owing to their sig-
nificant ring strains, π-character of the carbon–carbon bond
was remarkably enhanced, and as a result, the reaction
behaviour is analogous to an alkene in certain cases. For such
reasons, cyclopropanes have been paid much attention by
many synthetic chemists from the viewpoint of their syntheses
as well as synthetic applications.2
Incorporation of fluorine atom(s) into organic molecules
often alters their structure, stability, and reactivity, which fre-
quently leads to the discovery of their unexpected physical,
chemical, and biological properties.3 Therefore, fluorine-con-
taining substances have recently gained great interest in
various fields, such as materials, medicinal, agricultural, and
pharmaceutical sciences.4
Scheme 1 The present work.
In this article we wish to describe a novel synthesis of
various gem-difluorocyclopropanes via a highly regio- and
stereoselective radical hydrostannylation reaction of gem-
difluorocyclopropenes (Scheme 1). In addition, we would also
like to report a very unique ring-opening reaction involving
defluorination of the gem-difluorocyclopropylstannanes to
afford the corresponding β-monofluoroallylic alcohol deriva-
tives in an exclusively Z-selective manner.8
Consequently, it is not surprising that much effort has
been paid to the development of new synthetic methods for
the preparation of various gem-difluorocyclopropanes.5–7
Results and discussion
Hydrostannylation of various gem-difluorocyclopropenes
The various gem-difluorocyclopropenes 1a–j as starting
materials were easily prepared through the reaction of various
alkynes with commercially available TMSCF3 in the presence
of NaI according to a reported procedure.9 Thus, treatment of
1.0 equiv. of alkynes with 2.0 equiv. of TMSCF3 and 2.2 equiv.
of NaI in THF at 110 °C for 2 h in a sealed tube gave the corres-
Department of Chemistry and Materials Technology, Kyoto Institute of Technology,
Matsugasaki, Sakyo-ku, Kyoto, 606-8585 Japan. E-mail: konno@kit.ac.jp
†Electronic supplementary information (ESI) available: NMR spectra. See DOI:
10.1039/c5ob00046g
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Table 1 Hydrostannylation of gem-difluorocyclopropene 1a
Recoverya/%
of 1a
Entry
X/mol%
Temp./°C
Yielda/% of 2a-trans
1
2
3
4
20
20
20
10
0
20
20
20
0
rt
80
80
80
80
rt
81
81
19
19
0
9
80
0
Quant.
0
Quant. (Quant.)
91
20
Quant.
0
0
5
6b
7c
8c
60
a Determined by 19F NMR. The value in parentheses is of the isolated
yield. b AIBN was used instead of Et3B. c Pd(PPh3)4 was used instead of
Et3B.
Scheme 2 Preparation of various gem-difluorocyclopropenes.
ponding gem-difluorocyclopropene derivatives 1 in good to
excellent yields (Scheme 2).
was also obtained quantitatively (entry 6). In all cases, the
product was trans adduct only, and no other stereoisomers
could be detected at all. As shown in entry 7, palladium-
catalyzed hydrostannylation did not proceed at all and resulted
in quantitative recovery of starting material 1a. In the palla-
dium-catalyzed reaction at 60 °C, the desired hydrostannylated
adduct was not detected at all, although 1a was completely
consumed (entry 8).
Having the optimized reaction conditions in hand, we
examined the scope of this hydrostannylation using a variety
of gem-difluorocyclopropenes as shown in Table 2.
The hydrostannylation of symmetrical 1,2-diaryl-substituted
gem-difluorocyclopropene 1b took place very smoothly to give
the corresponding adduct 2b-trans in a highly stereoselective
manner (entry 2). However, disappointingly, there was con-
siderable deterioration of stereoselectivity in the case of sym-
metrical 1,2-dialkyl-substituted gem-difluorocyclopropene 1c
(entry 3). In unsymmetrical 1,2-diaryl-substituted gem-difluoro-
Initial studies on the hydrostannylation of gem-difluoro-
cyclopropenes began with the reaction of 1a with n-Bu3SnH in
the presence of Et3B, as shown in Table 1. Thus, treatment of
1.0 equiv. of 1a with 1.2 equiv. of n-Bu3SnH in the presence of
20 mol% of Et3B in toluene at 0 °C for 4 h gave the corres-
ponding adduct 2a-trans in 81% yield with recovery of 1a in
19% yield (entry 1). Although raising the reaction temperature
from 0 °C to room temperature did not result in any dramatic
change (entry 2), when the reaction was conducted at 80 °C,
on the other hand, the starting material 1a was completely
consumed, and 2a-trans was obtained quantitatively (entry 3).
As shown in entry 4, decreasing the amount of Et3B from
20 mol% to 10 mol% slightly influenced the yield; however the
desired adduct was still obtained in 91% yield. It should be
noted that the reaction proceeded even in the absence of a
radical initiator to afford 2a-trans in 20% yield but with a large
amount of unreacted starting material 1a (entry 5). When
AIBN was used as a radical initiator instead of Et3B, 2a-trans
Table 2 Hydrostannylation of various types of gem-difluorocyclopropene derivatives
Entry
R1
R2
Yielda,b/% of 2
2 (trans : cis) : 3 (trans : cis)
1
2
3
4
5
6
7
8
9
10
C6H5
C6H5
p-MeC6H4
BnOCH2
C6H5
C6H5
Me
BnOCH2
H
H
a
b
c
d
e
f
g
h
i
Quant. (Quant.)
98 (96)
74 (65)
99 (99)
86 (80)
(100 : 0) : —
(100 : 0) : —
(66 : 34) : —
55 (100 : 0) : 45 (100 : 0)
50 (100 : 0) : 50 (100 : 0)
100 (85 : 15) : 0
100 (90 : 10) : 0
100 (84 : 16) : 0
100 (50 : 50) : 0
100 (50 : 50) : 0
p-MeC6H4
BnOCH2
p-MeC6H4
p-NCC6H4
C6H5
C6H5
C6H5
92 (76)
Quant. (89)
Quant. (78)
Quant. (86)
78 (76)
n-C10H21
BnOCH2
H
j
a Determined by 19F NMR. b Values in parentheses are of isolated yields.
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cyclopropenes 1d and 1e, it was also revealed that the reaction
proceeded in a highly stereoselective manner but in a low
regioselective manner (entries 4 and 5). It should be noted
that the use of monoarylated gem-difluorocyclopropenes – 1f,
1g and 1h – brought about a high regio- and stereoselection
(entries 6–8). However, unsymmetrical monoalkyl-substituted
gem-difluorocyclopropenes 1i and 1j underwent a stereo-
random hydrostannylation reaction, although the regioselecti-
vity was very high (entries 9 and 10).
Stereochemical assignment of gem-difluorocyclopropyl-
stannanes
The stereochemical assignment of hydrostannylated products
2 and 3 was performed as follows. In both 2h-trans (major
isomer) and 2h-cis (minor isomers), a signal of the Ha proton
appears at 2.5–3.0 ppm, which is a much lower field than in
the case of 1,1-difluorocyclopropane (<2.0 ppm) (Fig. 1).10 This
fact strongly indicates that Ha might be deshielded owing to
the ring current effect of the benzene ring. Accordingly, it was
revealed that Ha and a phenyl group were bonded to the same
carbon C1, and thereby a stannyl group was bonded to another
carbon C2.
Generally, it is known that the H–F cis coupling constant, in
which the hydrogen atom has a cis configuration relationship
with the fluorine atom, is much larger than the H–F trans
coupling constant in cyclopropanes.11 From a careful analysis
of 1H or 19F NMR of 2h-trans, it was revealed that the coupling
constants for Ha–Fa, Ha–Fb, Hb–Fa, and Hb–Fb were 12.8, 2.0,
19.0, 12.8 Hz, respectively. For 2h-cis, it was also proved that
the coupling constants for Ha–Fa, Ha–Fb, Hb–Fa, and Hb–Fb
were 0, 8.8, 19.6, 8.2 Hz, respectively. These results unambigu-
ously suggest that 2h-trans and 2h-cis are trans and cis
adducts, respectively.
Scheme 3 Stereochemical assignment of 2j.
selective synthetic method (Scheme 3).12 Thus, hydro-
stannylation of benzyl propargyl ether 4 with 1.2 equiv. of
n-Bu3SnH in the presence of 2 mol% of Pd(PPh3)4 in toluene at
room temperature for 30 min gave the isomeric mixture of 5, 6
and 7 in 3%, 15% and 50% yield, respectively. Subsequently,
on treating the products 6 and 7 with 10 equiv. of sodium
chlorodifluoroacetate in diglyme at 180 °C for 1 h, the corres-
ponding gem-difluorocyclopropylstannanes 2j-cis and 3j were
obtained in 29% and 76% yield, respectively. Finally, compari-
son of 1H NMR in the gem-difluorocyclopropylstannanes pre-
pared from 1j with those prepared from 6 and 7 enabled us to
prove that in the case of using 1j, hydrostannylated products
consist of two stereoisomers, in both of which a stannyl group
is bonded on the remote carbon to a benzyloxymethyl group.
Based on the results, the stereochemical assignment of 2i was
also done in a similar way.
A reaction mechanism
The stereochemical assignments of other hydrostannylated
products 2a–e and 2g were made on the basis of the above
observation that in the unsymmetrical gem-difluorocyclopro-
penes having one aryl substituent, a stannyl group was bonded
on the remote carbon to an aryl substituent, and that trans
adducts were obtained preferentially.
A plausible reaction mechanism of this reaction is outlined in
Scheme 4. Thus, the addition of a tributylstannyl radical, gene-
rated by treating tributyltin hydride with Et3B/O2, toward gem-
difluorocyclopropene may give Int-1 and Int-2. If R1 is sterically
larger than R2, a tributylstannyl radical may favourably attack
On the other hand, the stereochemical assignment of 2j
was carried out by comparison with the gem-difluorocyclo-
propylstannane independently prepared via another stereo-
Fig. 1 Stereochemical assignment of 2h.
Scheme 4 A plausible reaction mechanism.
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the carbon connected with R2 due to a large repulsion between
R1 and a tributylstannyl group, resulting in the preferable for-
mation of Int-1. Even when only one side of substituents is
aryl (e.g., R1 = aryl, R2 = H, alkyl), Int-1 may also be generated
preferentially because the resulting benzylic radical is very
stable due to a resonance effect.13 Subsequently, tributyltin
hydride may come close to Int-1 by avoiding a bulky tributyl-
Table 3 Investigation of the reaction conditions
Quenching
Yielda/% Recoverya/%
stannyl group. Therefore, the corresponding trans adduct may Entry X/equiv. Temp./°C media
of 9a
of 2a-trans
be obtained preferentially.
1
1.1
1.1
1.1
1.1
1.5
1.5
1.5
1.5
1.5
−78
−78
−78
−78
−78
−78
−78
−60
0
aq. NH4Cl
aq. NH4Cl
aq. NH4Cl
aq. NH4Cl
aq. NH4Cl
H2O
3% aq. HCl 64 (51)
3% aq. HCl 52
3% aq. HCl 29
28
31
0
0
51
51
22
15
63
Quant.
0
0
0
0
23
2b
3c
4d
5
Synthetic application of gem-difluorocyclopropylstannanes
Next, our attention was directed toward the synthetic appli-
cation of gem-difluorocyclopropylstannanes.
6
7
8
9
First, the coupling reaction of 2a-trans with benzaldehyde
via the tin–lithium exchange reaction was examined
(Scheme 5). Thus, treatment of 2a-trans with 1.1 equiv. of
MeLi in THF at −78 °C for 15 min, followed by the addition of
benzaldehyde (1.1 equiv.) and quenching by saturated aq.
NH4Cl resulted in complete consumption of the starting
material 2a-trans but no formation of the expected coupling
adduct 8.14 Very intriguingly, β-fluoroallylic alcohol 9a was
obtained in 26% yield in an exclusively Z-selective manner.15
Even when this coupling reaction was carried out in the
manner of a Barbier type reaction,16 no trace of 8 was detected
at all, but 9a was given in 10% yield with an excellent Z-selecti-
vity (not shown in Scheme 5).
a Determined by 19F NMR. The value in parentheses is of the isolated
yield. b HMPA (1.0 equiv.) was used. c n-BuLi was used instead of MeLi.
d Et2O was used as a solvent instead of THF.
Table 4 Ring-opening reaction with various alcohols
This very unique ring-opening reaction engaged our aca-
demic interest and prompted us to investigate the reaction
conditions deeply. The results are summarized in Table 3.
Even when 2a-trans was treated with MeLi (1.1 equiv.) in
THF at −78 °C for 5 min without aldehyde but with aq. NH4Cl,
9a was obtained in 28% yield (entry 1). In this case, 22% of the
starting material still remained unreacted. No improvement
was observed by the addition of HMPA (entry 2). The reaction
did not proceed with either n-BuLi or Et2O (entries 3 and 4).
The yield of 9a was greatly enhanced when the amount of
MeLi was increased from 1.1 equiv. to 1.5 equiv. (entry 5). H2O
was also available to quench the reaction (entry 6). On the
other hand, quenching the reaction with 3% aq. HCl instead
of aq. NH4Cl led to the best reaction yield (entry 7). However,
higher temperature, such as −60 °C and 0 °C, decreased the
yield (entries 8 and 9).
Entrya
R3OH
Product
Yieldb/% of 9
1
2
3
4
5
6
7
8
9
H2O
n-C6H13OH
MeOCH2CH2OH
p-MeOC6H5CH2OH
i-PrOH
(S)-CH3(OH)CHCO2Et
tert-BuOH
9a
9b
9c
9d
9e
9f
9g
9h
9i
64 (51)
60
58 (41)
51 (50)
48
55 (55)c
59 (57)
21
PhOH
2,4,6-Me3C6H2OH
57 (47)
a In all reactions,
Z
isomers were obtained as
a
sole product.
b Determined by 19F NMR. Values in parentheses are of isolated yields.
c The diastereomeric ratio of the product is 1 : 1.
n-hexyl alcohol, ethylene glycol monomethyl ether and p-meth-
oxybenzyl alcohol, could be suitable for this chemical trans-
formation (entries 2–4). Furthermore, much bulkier secondary
and tertiary alcohols than primary ones, such as isopropyl
alcohol, ethyl lactate and tert-butylalcohol, could also partici-
pate in this reaction very well (entries 5–7). Although phenol
showed poor reaction yield (entry 8), 2,4,6-trimethylphenol
served well as a quenching agent (entry 9).
Under the best reaction conditions, various alcohols were
tested as a quenching agent. The results are shown in Table 4.
Generally, it was revealed that various types of alcohols
and phenols could be successfully applied for the reaction
as quenching reagents. For example, primary alcohols, such as
Other quenching reagents, in addition to H2O and various
alcohols, were investigated as summarized in Table 5.
Carboxylic acids, such as acetic acid and benzoic acid, were
found to be good quenching reagents, and the corresponding
β-fluoroallyl esters 9j and 9k were obtained in good yield. Ben-
zylamine and carbamate showed no reaction (entries 3 and 4).
β-Fluoroallylamide 9n was provided only in 19% yield by
Scheme 5 A coupling reaction of 2a-trans with benzaldehyde.
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Table 5 Ring-opening reaction with various carboxylic acids, amides,
and thiols
Entrya
R3XH
Product
Yieldb/% of 9
1
2
3
4
5
6
7
8
MeCOOH
PhCOOH
BnNH2
BocNH2
CF3CONH2
p-MeC6H4SO2NH2
p-MeC6H4SH
PhCH2SH
9j
9k
9l
9m
9n
9o
9p
9q
56 (54)
60 (47)
0
0
19
71 (60)
0
0
a In all reactions, Z isomers were obtained as the sole product.
b Determined by 19F NMR. Values in parentheses are of isolated yields.
quenching with trifluoroacetamide, but p-toluenesulfonamide
gave the corresponding β-fluoroallylamide 9o in 71% yield.
Disappointingly, various thiols, such as toluenethiol and
benzyl mercaptane, gave no products at all (entries 7 and 8).
We also examined the ring-opening reaction with other
gem-difluorocyclopropylstannanes (Scheme 6). The symmetri-
cal gem-difluorocyclopropylstannane having two tolyl groups,
2b-trans, could participate in the reaction nicely to provide the
corresponding β-fluoroallyl alcohol 9r in an exclusively Z selec-
tive manner. In addition, the unsymmetrical substrates 2d-
trans/3d-trans having a phenyl and a tolyl substituent under-
went a smooth ring-opening reaction with a mixture of regio-
isomers in a ratio of 62 : 38. However, in the case of 2c-trans/
2c-cis, 2e-trans/3e-trans, and 2h-trans/2h-cis, the starting
stannanes were completely consumed but with no trace of the
desired β-fluoroallylic alcohol derivatives.
A plausible reaction mechanism
In order to elucidate the reaction pathway, we tested quench-
ing the reaction with D2O. Consequently, it was revealed that
the deuterated adducts 10a and 10b were obtained in a ratio of
1 : 1 (Scheme 7). Based on the deuteration experiment as well
as the fact that nonfluorinated cyclopropenes 11 and 12 were
detected as byproducts in some cases (Fig. 2), a plausible
mechanism of this unique ring-opening reaction can be
presented as follows (Scheme 8).
Scheme 6 Ring-opening reaction of other gem-difluorocyclo-
propylstannanes.
First, the tin–lithium exchange reaction may take place to
give the corresponding gem-difluorocyclopropyl lithium inter-
mediate Int-3, which may undergo β-elimination to afford the
monofluorocyclopropene Int-4. This monofluorocyclopropene
may partially react with MeLi, leading to the corresponding
nonfluorinated trisubstituted cyclopropenes 11 via the
addition–elimination pathway. In the case of alcohols as a
quenching agent, treating the reaction with R3OH may
partially cause the substitution of R3O− toward Int-4 via the
addition–elimination pathway, providing the cyclopropenyl Scheme 7 Quenching the reaction with D2O.
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β-fluoroallylic framework at the point of quenching the
reaction.
Experimental section
Fig. 2 Byproducts.
General information
Infrared spectra (IR) were recorded in a liquid film on a NaCl
plate or KBr disks using a JASCO FT/IR-4100 type A spectro-
meter. 1H and 13C NMR spectra were recorded with a JEOL
JNM-AL 400 NMR spectrometer in a chloroform-d (CDCl3)
solution as an internal standard. A JEOL JNM-AL 400 NMR
spectrometer was used for determining the yield of the pro-
ducts with hexafluorobenzene (C6F6). 19F NMR (376.05 MHz)
spectra were recorded with a JEOL JNM-AL 400 NMR spectro-
meter in a chloroform-d (CDCl3) solution with trichlorofluoro-
methane (CFCl3) as an internal standard. High-resolution
mass spectra (HRMS) were recorded on a JEOL JMS-700MS
spectrometer by the fast atom bombardment (FAB) method.
All reactions were routinely monitored by 19F NMR spectro-
scopy or TLC, and carried out under an argon atmosphere.
All chemicals were of reagent grade and, if necessary, were
purified in the usual manner prior to use. Thin-layer chromato-
graphy (TLC) was performed with Merck silica gel 60 F254
plates, and column chromatography was carried out using
Wako gel C-200 as an adsorbent.
General procedure for the preparation of gem-difluorocyclo-
propene 1
Alkyne (1.0 mmol, 1.0 equiv.), TMSCF3 (0.3 mL, 2.0 mmol,
2.0 equiv.), NaI (0.33 g, 2.2 mmol, 2.2 equiv.), and THF (3 mL)
were mixed in a sealed tube at room temperature. Then the
reaction mixture was heated at 110 °C for 2 h. The reaction was
quenched by adding saturated aq. Na2CO3 at 0 °C, followed by
extraction with Et2O three times. The combined organic layers
were dried over anhydrous Na2SO4, filtered, and concentrated
in vacuo. The residue was purified by silica gel column chrom-
atography (the column should be eluted previously with
hexane–Et3N) to give the corresponding cyclopropene 1.
Scheme 8 A plausible mechanism of the ring-opening reaction.
ether 12. On the other hand, it is highly possible that Int-4
mainly invokes a thermal ring-opening reaction to provide the
corresponding carbene Int-5, which is significantly stabilized
by the resonance effect of an aromatic ring.17 Finally, exposure
of Int-5 to a quenching agent (R3XH) may lead to the corres-
ponding β-fluoroallylic alcohols, ethers, and amides 9. Given
that the reaction may proceed through the carbene Int-5, it is
obvious that quenching the reaction with D2O results in the
stereorandom formation of 10a and 10b.
1,2-Bis(benzyloxymethyl)-3,3-difluorocyclopropene (1c). Color-
less liquid; IR (neat) 3064, 3032, 2861, 1813, 1587, 1496,
1455, 1362, 1304, 1097, 1027, 907, 822, 739, 697 cm−1; HRMS
1
(FAB) calcd for (M+) C19H18F2O2: 316.1275, found 316.1265; H
NMR (CDCl3) δ = 4.53–4.54 (m, 4H), 4.61–4.62 (m, 4H),
7.30–7.39 (m, 10H) ppm; 13C NMR (CDCl3) δ = 61.8, 72.8 (t, J =
1.7 Hz), 103.0 (t, J = 271.1 Hz), 127.96, 128.04, 128.2 (t, J =
11.6 Hz), 128.5, 136.9 ppm; 19F NMR (CDCl3) δ = −104.92 (s,
Conclusions
In conclusion, we have demonstrated the highly regio- and 2F) ppm.
stereoselective synthesis of various gem-difluorocyclopropyl- 3,3-Difluoro-1-phenyl-2-p-tolylcyclopropene
(1d). White
stannanes via a radical hydrostannylation reaction of gem- solid; M.P.: 62–63 °C; IR (KBr) 2962, 2345, 2226, 1777, 1597,
difluorocyclopropenes. In addition, we have discovered the 1450, 1358, 1321, 1279, 1178, 1107, 999, 843, 767, 685, 574,
unique ring-opening reaction of gem-difluorocyclopropylstan- 539, 462, 445 cm−1; HRMS (FAB) calcd for (M+) C16H12F2:
nanes through the carbene intermediate, providing β-fluoro- 242.0907, found 242.0898; 1H NMR (CDCl3) δ = 2.44 (s, 3H),
allylic alcohols, ethers, and amides in a highly Z selective 7.33 (d, J = 8.19 Hz, 2H), 7.47–7.55 (m, 3H), 7.69 (d, J =
manner. In this reaction, it should be noted that a hetero- 8.19 Hz, 2H), 7.77–7.79 (m, 2H) ppm; 13C NMR (CDCl3) δ =
atom-containing substituent can be introduced into the 21.7, 102.4 (t, J = 270.7 Hz), 121.7, 121.9 (t, J = 11.1 Hz), 123.1
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(t, J = 10.7 Hz), 124.7, 128.6, 129.9, 130.2, 130.3, 130.7, (M + Na) C27H38F2NaSn: 543.1861, found 543.1877; 1H NMR
141.6 ppm; 19F NMR (CDCl3) δ = −112.67 (s, 2F) ppm.
(CDCl3) δ = 0.45–0.62 (m, 6H), 0.78 (t, J = 7.19 Hz, 9H),
3,3-Difluoro-1-(4-cyanophenyl)-2-phenylcyclopropene
(1e). 1.07–1.43 (m, 12H), 3.10 (d, J = 14.33 Hz, 1H), 7.16–7.47 (m,
White solid; M.P.: 155–156 °C; IR (KBr) 3037, 2923, 2868, 2206, 10H) ppm; 13C NMR (CDCl3) δ = 10.2, 13.5, 27.1, 28.6, 38.2 (dd,
1969, 1950, 1868, 1780, 1722, 1610, 1515, 1449, 1372, 1022, J = 12.0, 9.5 Hz), 38.8 (dd, J = 27.7, 4.5 Hz), 115.8 (dd, J = 293.5,
835, 811, 685, 568, 542, 473 cm−1; HRMS (FAB) calcd for 285.9 Hz), 125.6, 127.3, 128.3 (d, J = 2.5 Hz), 128.4, 128.7,
(M + H) C16H10F2N: 254.0781, found 254.0780; 1H NMR 129.6, 136.3 (d, J = 1.7 Hz), 140.9–141.0 (m) ppm; 19F NMR
(CDCl3) δ = 7.56–7.57 (m, 3H), 7.78–7.89 (m, 6H) ppm; 13C (CDCl3) δ = −117.43 (d, J = 139.14 Hz, 1F), −124.75 (dd, J =
NMR (CDCl3) δ = 101.3 (t, J = 272.3 Hz), 114.1, 118.1, 139.14, 14.33 Hz, 1F) ppm.
121.0–121.3 (m), 123.8, 126.9 (t, J = 10.7 Hz), 128.7, 129.4,
130.5, 130.7, 131.9, 132.9 ppm; 19F NMR (CDCl3) δ = −112.80 stannane (2b-trans). White solid; M.P.: 36 °C; IR (neat) 2956,
(s, 2F) ppm. 2924, 2871, 2360, 1730, 1511, 1434, 1402, 1377, 1288, 1233,
(1S*,3R*)-Tributyl(2,2-difluoro-1,3-di-p-tolylcycloprop-1-yl)-
1-Benzyloxymethyl-3,3-difluoro-2-phenylcyclopropene (1g). 1207, 1160, 1062, 1011, 959, 882, 839, 819, 719, 692 cm−1
;
Colorless liquid; IR (neat) 3064, 3032, 2862, 1809, 1601, 1495, HRMS (FAB) calcd for (M+) C29H42F2Sn: 548.2277, found
1
1453, 1365, 1287, 1095, 1014, 824, 766, 738, 692 cm−1; HRMS 548.2286; H NMR (CDCl3) δ = 0.44–0.61 (m, 6H), 0.78 (t, J =
1
(FAB) calcd for (M+) C17H14F2O: 272.1017, found 272.1013; H 7.19 Hz, 9H), 1.07–1.19 (m, 12H), 2.34 (s, 3H), 2.35 (s, 3H),
NMR (CDCl3) δ = 4.66–4.67 (m, 4H), 7.32–7.51 (m, 8H), 3.01 (d, J = 14.33 Hz, 1H), 7.12–7.17 (m, 6H), 7.33 (d, J =
7.68–7.70 (m, 2H) ppm; 13C NMR (CDCl3) δ = 62.5, 73.0 (t, J = 7.59 Hz, 2H) ppm; 13C NMR (CDCl3) δ = 10.2, 13.5, 21.0, 21.1,
1.7 Hz), 102.7 (t, J = 271.6 Hz), 123.5, 124.4 (t, J = 12.4 Hz), 27.2, 28.6, 37.8 (dd, J = 11.6, 9.1 Hz), 38.5 (dd, J = 27.7, 4.5 Hz),
127.95, 128.07, 128.09 (t, J = 10.7 Hz), 128.6, 129.0, 130.6, 116.1 (dd, J = 293.4, 278.6 Hz), 128.5 (d, J = 2.51 Hz), 129.1,
131.0, 137.0 ppm; 19F NMR (CDCl3) δ = −107.72 (s, 2F) ppm.
129.3, 129.5, 133.3–133.4 (m), 135.1, 136.7, 137.88–137.92 (m)
1-n-Decyl-3,3-difluorocyclopropene (1i). Colorless liquid; IR ppm; 19F NMR (CDCl3) δ = −117.53 (d, J = 138.95 Hz, 1F),
(neat) 3131, 2927, 2856, 1722, 1467, 1311, 1023, 786, 721 cm−1
HRMS (FAB) calcd for (M+) C13H22F2: 216.1690, found
;
−124.93 (dd, J = 138.95, 14.33 Hz, 1F) ppm.
Tributyl[1,2-bis(benzyloxymethyl)-3,3-difluorocycloprop-1-yl]-
216.1683; 1H NMR (CDCl3) δ = 0.88 (t, J = 6.79 Hz, 3H), stannane (2c). Colorless liquid; trans : cis = 66 : 34; IR (neat)
1.27–1.39 (m, 14H), 1.62 (quint., J = 7.34 Hz, 2H), 2.49 (tt, J = 3064, 3032, 2955, 2924, 2855, 1454, 1405, 1376, 1361, 1295,
7.34, 2.40 Hz, 2H), 7.20–7.21 (m, 1H) ppm; 13C NMR (CDCl3) 1200, 1184, 1075, 1028, 876, 737, 697 cm−1; HRMS (FAB) calcd
δ = 14.1, 22.7, 23.7, 26.4, 28.9, 29.2, 29.3, 29.4, 29.5, 31.9, 103.0 for (M+) C31H46F2O2Sn: 608.2488, found 608.2493; 1H NMR
(t, J = 273.1 Hz), 116.9–117.1 (m), 138.2 (t, J = 10.7 Hz), ppm; (CDCl3) δ = 0.82–1.48 (m, 28H), 3.42–3.72 (m, 4H), 4.38–4.56
19F NMR (CDCl3) δ = −104.67 (s, 2F) ppm.
(m, 4H), 7.29–7.34 (m, 10H) ppm; trans adduct: 19F NMR
1-Benzyloxymethyl-3,3-difluorocyclopropene (1j). Colorless (CDCl3) δ = −125.29 (d, J = 150.14 Hz, 1F), −134.67 (dd, J =
liquid; IR (neat) 2935, 2861, 1721, 1455, 1362, 1309, 1100, 150.14, 12.22 Hz, 1F) ppm; cis adduct: 19F NMR (CDCl3) δ =
1029, 741, 698 cm−1; HRMS (FAB) calcd for (M+) C11H10F2O: −114.18 (dm, J = 150.14 Hz, 1F), −147.79 (dm, J = 150.14 Hz,
196.0700, found 196.0693; 1H NMR (CDCl3) δ = 4.54 (dt, J = 1F) ppm.
1.85, 1.85 Hz, 2H), 4.62 (s, 2H), 7.31–7.40 (m, 5H), 7.45 (tt, J =
(1S*,3R*)-Tributyl(2,2-difluoro-1-phenyl-3-p-tolylcycloprop-
1.85, 1.85 Hz, 1H) ppm; 13C NMR (CDCl3) δ = 62.3, 72.9 (t, J = 1-yl)stannane (2d-trans), (1S*, 3R*)-tributyl(2,2-difluoro-3-
1.7 Hz), 101.7 (t, J = 269.9 Hz), 118.4–118.7 (m), 128.0, 128.2, phenyl-1-p-tolylcycloprop-1-yl)stannane (3d-trans). Colorless
128.6, 135.6 (t, J = 11.6 Hz), 136.8 ppm; 19F NMR (CDCl3) δ = liquid; isomeric ratio = 55 : 45; IR (neat) 2956, 2924, 2850,
−103.82 (s, 2F) ppm.
1597, 1496, 1430, 1286, 1161, 1059, 809 cm−1; HRMS (FAB)
1
calcd for (M+) C28H40F2Sn: 534.2120, found 534.2129; H NMR
Typical procedure for the hydrostannation of gem-difluoro-
cyclopropene
(CDCl3) δ = 0.44–0.60 (m, 6H), 0.78 (t, J = 7.19 Hz, 9H),
1.11–1.20 (m, 12H), 2.34 (s, 3H) and 2.36 (s, 3H), 3.05 (d, J =
To a solution of 3,3-difluoro-1,2-diphenylcyclopropene 1a 14.13, 13.00 Hz, 1H), 7.12–7.46 (m, 9H) ppm; major isomer:
(0.055 g, 0.24 mmol, 1.0 equiv.) and tributyltin hydride 19F NMR (CDCl3) δ = −117.51 (d, J = 139.14 Hz, 1F), −124.75
(0.08 mL, 0.3 mmol, 1.2 equiv.) in THF (1.0 mL) was added a (dd, J = 139.14, 14.13 Hz, 1F) ppm; minor isomer: 19F NMR
hexane solution of Et3B (0.05 mL, 0.05 mmol, 1.0 M hexane (CDCl3) δ = −117.44 (d, J = 139.14 Hz, 1F), −124.92 (dd, J =
solution, 20 mol%) at room temperature. Then the whole 139.14, 13.00 Hz, 1F) ppm.
mixture was stirred at 80 °C for 4 h. After the whole mixture
(1S*, 3R*)-Tributyl[2-(4-cyanophenyl)-3,3-difluoro-1-phenyl-
was allowed to cool to room temperature, the mixture was con- cycloprop-1-yl]stannane (2e-trans), (1S*, 3R*)-tributyl[1-(4-
centrated in vacuo. The residue was chromatographed on a cyanophenyl)-2,2-difluoro-3-phenylcycloprop-1-yl]stannane (3e-
silica gel (hexane–EtOAc = 10/1) to afford the corresponding trans). Yellow liquid; isomeric ratio = 50 : 50; IR (neat) 2956,
hydrostannylated product 2a (0.125 g, 0.24 mmol, quant.).
2925, 2871, 2854, 2228, 1604, 1499, 1463, 1428, 1377, 1287,
(1S*,3R*)-Tributyl(2,2-difluoro-1,3-diphenylcycloprop-1-yl)- 1216, 1077, 1056, 1009, 959, 879, 830, 699, 561 cm−1; HRMS
stannane (2a-trans). Colorless liquid; IR (neat) 3060, 3026, (FAB) calcd for (M+) C28H37F2NSn: 545.1916, found 545.1915;
2956, 2925, 2871, 2854, 1600, 1494, 1427, 1289, 1232, 1162, 1H NMR (CDCl3) δ = 0.45–0.62 (m, 6H), 0.77–0.80 (m, 9H),
1058, 1009, 948, 866, 741, 706 cm−1; HRMS (FAB) calcd for 1.10–1.25 (m, 12H), 3.06–3.10 (m, 1H), 7.20–7.69 (m, 9H) ppm;
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19F NMR (CDCl3) δ = −117.28 (d, J = 142.10 Hz, 1F) and trans adduct: 19F NMR (CDCl3) δ = −120.47 (ddd, J = 144.60,
−117.90 (d, J = 142.10 Hz, 1F), −124.02 (dd, J = 142.10, 14.67 15.80, 10.91 Hz, 1F), −133.16 (dd, J = 144.60, 12.41 Hz, 1F)
Hz, 1F) and −124.69 (dd, J = 142.10, 12.22 Hz, 1F) ppm.
ppm; cis adduct: 19F NMR (CDCl3) δ = −119.07 (dm, J = 146.38
Tributyl(2,2-difluoro-1-methyl-3-phenylcycloprop-1-yl)stannane Hz, 1F), −136.82 (dd, J = 146.38, 19.37 Hz, 1F) ppm.
(2f). Colorless liquid; trans : cis = 85 : 15; IR (neat) 2956, 2925,
Hydrostannylation of 3-benzyloxypropyne
HRMS (FAB) calcd for (M+) To a stirring solution of 3-benzyloxypropyne (0.43 g, 3 mmol,
2871, 1499, 1456, 1424, 1377, 1284, 1180, 1149, 1093, 987, 959,
877, 745, 698, 664 cm−1
;
1
C22H36F2Sn: 458.1807, found 458.1815; trans adduct: H NMR 1.0 equiv.) and Pd(PPh3)4 (0.069 g, 0.06 mmol, 2 mol%) in
(CDCl3) δ = 0.52–1.51 (m, 30H), 2.43 (dd, J = 12.81, 2.40 Hz, toluene (15 mL) at room temperature was added n-Bu3SnH
1H), 7.20–7.32 (m, 5H) ppm; 19F NMR (CDCl3) δ = −119.71 (d, (0.96 mL, 3.6 mmol, 1.2 equiv.). Then the whole mixture was
J = 143.84 Hz, 1F), −133.35 (dd, J = 143.84, 12.81 Hz, 1F) ppm; stirred at room temperature for 30 min. The mixture was con-
cis adduct: 1H NMR (CDCl3) δ = 0.52–1.51 (m, 30H), 2.64 (d, J = centrated in vacuo. The residue was chromatographed on a
8.79 Hz, 1H), 7.20–7.32 (m, 5H) ppm; 19F NMR (CDCl3) δ = silica gel (hexane–benzene = 5/1) to afford the corresponding
−108.03 (dm, J = 147.13 Hz, 1F), −144.00 (d, J = 147.13 Hz, 1F) hydrostannylated products 5 (0.037 g, 0.08 mmol, 3%), 6
ppm.
(0.20 g, 0.46 mmol, 15%), and 7 (0.66 g, 1.5 mmol, 50%).
Tributyl(1-benzyloxymethyl-2,2-difluoro-3-phenylcycloprop-1-
yl)stannane (2g). Colorless liquid; trans : cis = 90 : 10; IR (neat)
General procedure for the reaction of vinylstannane with
difluorocarbene
3063, 3031, 2955, 2924, 2853, 1498, 1455, 1428, 1359, 1289,
1184, 1074, 961, 907, 746, 698 cm−1; HRMS (FAB) calcd for To a solution of vinylstannane (0.2 mmol, 1.0 equiv.) in
1
(M+) C29H42F2OSn: 564.2226, found 564.2230; trans adduct: H diglyme (0.60 mL) was dropwise added ClF2CCO2Na (0.30 g,
NMR (CDCl3) δ = 0.52–1.52 (m, 27H), 2.64 (d, J = 14.13 Hz, 1H), 2.0 mmol, 10 equiv.) in diglyme (6.0 mL) at 180 °C. Then the
3.67–3.73 (m, 2H), 4.53 (d, J = 11.59 Hz, 1H), 4.58 (d, J = 11.59 whole mixture was stirred at that temperature for 1 h. After the
Hz, 1H), 7.24–7.37 (m, 10H) ppm; 19F NMR (CDCl3) δ = whole mixture was allowed to cool to room temperature, the
−120.48 (d, J = 148.92 Hz, 1F), −130.67 (dd, J = 148.92, 14.13 reaction mixture was poured into H2O. Then the mixture was
Hz, 1F) ppm; cis adduct: 1H NMR (CDCl3) δ = 0.52–1.52 (m, extracted with hexane three times. The combined organic
27H), 2.78 (d, J = 8.87 Hz, 1H), 3.67–3.68 (m, 2H), 4.26 (d, J = layers were dried over anhydrous Na2SO4, filtered, and concen-
11.99 Hz, 1H), 4.37 (d, J = 11.99 Hz, 1H), 7.24–7.37 (m, 10H) trated in vacuo. The residue was purified by silica gel column
ppm; 19F NMR (CDCl3) δ = −109.90 (dd, J = 151.55, 8.87 Hz, chromatography (hexane–EtOAc = 10/1) to give the corres-
1F), −143.15 (d, J = 151.55 Hz, 1F) ppm.
ponding cyclopropylstannane.
Tributyl(2,2-difluoro-3-phenylcycloprop-1-yl)stannane (2h).
Tributyl(1-benzyloxymethyl-2,2-difluorocycloprop-1-yl)stannane
Colorless liquid; trans : cis = 84 : 16; IR (neat) 2957, 2925, 2871, (3j). This compound was inseparable from byproducts. HRMS
2853, 1604, 1499, 1463, 1425, 1291, 1229, 1195, 1116, 1064, (FAB) calcd for (M+) C23H38F2OSn: 488.1913, found 488.1907;
1020, 929, 745, 698 cm−1; HRMS (FAB) calcd for (M+) 1H NMR (CDCl3) δ = 0.83–1.51 (m, 29H), 3.40 (d, J = 9.59 Hz,
1
C21H34F2Sn: 444.1651, found 444.1647; trans adduct: H NMR 1H), 3.62 (dd, J = 9.59, 4.40 Hz, 1H), 4.43 (d, J = 11.79 Hz, 1H),
(CDCl3) δ = 0.57–1.53 (m, 28H), 3.02 (dt, J = 2.0, 12.8 Hz, 1H), 4.53 (d, J = 11.79 Hz, 1H), 7.28–7.34 (m, 5H) ppm; 19F NMR
7.22–7.32 (m, 5H) ppm; 19F NMR (CDCl3) δ = −115.94 (ddd, J = (CDCl3) δ = −117.17 (dm, J = 148.92, 1F), −140.67 (dd, J =
144.03, 19.55, 12.80 Hz, 1F), −128.60 (dd, J = 144.03, 12.03 Hz, 148.92, 12.03 Hz, 1F) ppm.
1
1F) ppm; cis adduct: H NMR (CDCl3) δ = 0.57–1.53 (m, 28H),
General procedure for the ring-opening reaction
2.55 (t, J = 8.79 Hz, 1H), 7.20–7.32 (m, 5H) ppm; 19F NMR
(CDCl3) δ = −115.11 (dt, J = 141.39, 8.79 Hz, 1F), −135.93 (dd, To a solution of cyclopropylstannane 2 (0.3 mmol, 1.0 equiv.)
J = 141.39, 19.55 Hz, 1F) ppm.
in THF (1.2 mL) was added dropwise an ethereal solution of
Tributyl(2-n-decyl-3,3-difluorocycloprop-1-yl)stannane (2i). MeLi (0.4 mL, 0.45 mmol, 1.07 M Et2O solution, 1.5 equiv.) at
Colorless liquid; trans : cis = 50 : 50; IR (neat) 2957, 2925, 2855, −78 °C. Then the whole mixture was stirred at that tempera-
1440, 1377, 1342, 1293, 1219, 1109, 1072, 959, 876 cm−1
;
ture for 5 min, followed by quenching the reaction with 3% aq.
HRMS (FAB) calcd for (M+) C25H50F2Sn: 508.2903, found HCl, alcohol, carboxylic acid (12 mmol, 40 equiv.) or amide
1
508.2906; H NMR (CDCl3) δ = 0.86–1.54 (m, 50H) ppm; trans (6 mmol, 20 equiv.) in THF (a quenching agent–THF = 1/5,
adduct: 19F NMR (CDCl3) δ = −119.76 (ddd, J = 139.94, 17.77, v/v). After the whole mixture was allowed to warm to room
12.88 Hz, 1F), −135.10 (dd, J = 139.94, 12.22 Hz, 1F) ppm; cis temperature, the mixture was extracted with Et2O three times.
adduct: 19F NMR (CDCl3) δ = −117.74 (dt, J = 141.39, 9.78 Hz, The combined organic layers were dried over anhydrous
1F), −137.22 (dd, J = 141.39, 19.55 Hz, 1F) ppm.
Na2SO4, filtered, and concentrated in vacuo. The residue was
Tributyl(2-benzyloxymethyl-3,3-difluorocycloprop-1-yl)stannane purified by silica gel column chromatography (hexane–EtOAc =
(2j). Colorless liquid; trans : cis = 50 : 50; IR (neat) 2956, 2926, 10/1–5/1) to give the corresponding alcohols, ethers, esters,
2855, 1445, 1361, 1291, 1215, 1157, 1106, 1054, 1024, 876, 736, and amide 9.
697 cm−1; HRMS (FAB) calcd for (M+) C23H38F2OSn: 488.1913,
(Z)-2-Fluoro-1,3-diphenyl-2-propen-1-ol (9a). White solid;
found 488.1923; 1H NMR (CDCl3) δ = 0.55–2.14 (m, 29H), M.P.: 53–54 °C; IR (KBr) 3387, 3028, 2345, 1952, 1686, 1601,
3.42–3.68 (m, 2H), 4.47–4.60 (m, 2H), 7.27–7.35 (m, 5H) ppm; 1494, 1449, 1321, 1274, 1156, 1023, 894, 862, 841, 752, 724,
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693, 517 cm−1; HRMS (FAB) calcd for (M + H) C15H14FO: −114.23 (dd, J = 38.74, 12.41 Hz, 1F) and −115.45 (dd, J =
1
229.1029, found 229.1029; H NMR (CDCl3) δ = 2.38 (brs, 1H), 38.18, 18.01 Hz, 1F) ppm.
5.29 (dd, J = 11.91, 3.80 Hz, 1H), 5.87 (d, J = 38.94 Hz, 1H),
(Z)-3-t-Butoxy-2-fluoro-1,3-diphenyl-1-propene (9g). Yellow
7.18–7.47 (m, 10H) ppm; 13C NMR (CDCl3) δ = 73.2 (d, J = 31.3 liquid; IR (neat) 3060, 3028, 2975, 2925, 1692, 1601, 1495,
Hz), 107.0 (d, J = 5.7 Hz), 126.8, 127.5 (d, J = 2.5 Hz), 128.5, 1450, 1391, 1368, 1253, 1190, 1066, 1024, 910, 734, 694 cm−1
;
128.6, 128.7, 128.8 (d, J = 7.4 Hz), 132.7 (d, J = 2.5 Hz), 139.4, HRMS (FAB) calcd for (M+) C19H21FO: 284.1576, found
159.2 (d, J = 267.9 Hz) ppm; 19F NMR (CDCl3) δ = −115.53 (dd, 284.1570; 1H NMR (CDCl3) δ = 1.28 (s, 9H), 5.13 (d, J = 9.78 Hz,
J = 38.94, 11.91 Hz, 1F) ppm.
1H), 5.78 (d, J = 38.94 Hz, 1H), 7.19–7.49 (m, 10H) ppm; 13C
(Z)-2-Fluoro-3-n-hexyloxy-1,3-diphenyl-1-propene (9b). This NMR (CDCl3) δ = 28.3, 72.6–72.9 (m), 75.7, 106.7 (d, J = 7.4 Hz),
compound was inseparable from byproducts; HRMS (FAB) 127.0, 127.1 (d, J = 2.5 Hz), 127.7, 128.26, 128.33, 128.6 (d, J =
calcd for (M+) C21H25FO: 312.1889, found 312.1891; 1H NMR 7.4 Hz), 133.2 (d, J = 3.3 Hz), 140.7, 160.6 (d, J = 270.3 Hz)
(CDCl3) δ = 0.87–1.70 (m, 11H), 3.58–3.66 (m, 2H), 4.88 (d, J = ppm; 19F NMR (CDCl3) δ = −111.62 (dd, J = 38.94, 9.78 Hz, 1F)
14.53 Hz, 1H), 5.86 (d, J = 39.14 Hz, 1H), 7.21–7.51 (m, 10H) ppm.
ppm; 19F NMR (CDCl3) δ = −114.48 (dd, J = 39.14, 14.53 Hz,
1F) ppm.
(Z)-2-Fluoro-3-phenoxy-1,3-diphenyl-1-propene
compound was inseparable from byproducts. HRMS (FAB)
(9c). calcd for (M+) C21H17FO: 304.1263, found 304.1273; 1H NMR
(9h). This
(Z)-2-Fluoro-3-methoxyethoxy-1,3-diphenyl-1-propene
Yellow liquid; IR (neat) 3060, 3028, 2925, 1692, 1601, 1495, 5.74 (d, J = 12.00 Hz, 1H), 5.89 (d, J = 38.74 Hz, 1H), 6.97–7.55
1450, 1278, 1199, 1132, 1092, 1030, 916, 851, 755, 695 cm−1
;
(m, 15H) ppm; 19F NMR (CDCl3) δ = −114.01 (dd, J = 38.74,
HRMS (FAB) calcd for (M+) C18H19FO2: 286.1369, found 12.00 Hz, 1F) ppm.
1
286.1359; H NMR (CDCl3) δ = 3.41 (s, 3H), 3.58–3.80 (m, 4H),
(Z)-2-Fluoro-3-(2,4,6-trimethylphenoxy)-1,3-diphenyl-1-propene
4.99 (d, J = 14.44 Hz, 1H), 5.90 (d, J = 38.65 Hz, 1H), 7.15–7.51 (9i). White solid; M.P.: 99–100 °C; IR (KBr) 2920, 2372, 2345,
(m, 10H) ppm; 13C NMR (CDCl3) δ = 59.1, 68.6, 71.9, 80.7–81.0 1686, 1638, 1573, 1479, 1449, 1272, 1207, 1146, 1079, 1007,
(m), 107.9–108.0 (m), 127.3, 127.4 (d, J = 2.5 Hz), 128.31, 873, 788, 716, 693, 470 cm−1; HRMS (FAB) calcd for (M+)
128.39, 128.44, 128.8 (d, J = 7.4 Hz), 132.7 (d, J = 3.3 Hz), 137.8, C24H23FO: 346.1733, found 346.1732; 1H NMR (CDCl3) δ = 2.13
157.7 (d, J = 269.5 Hz) ppm; 19F NMR (CDCl3) δ = −114.75 (dd, (s, 6H), 2.23 (s, 3H), 5.21 (d, J = 19.48 Hz, 1H), 5.86 (d, J =
J = 38.65, 14.44 Hz, 1F) ppm.
37.12 Hz, 1H), 6.79 (s, 2H), 7.26–7.58 (m, 10H) ppm; 13C NMR
(Z)-2-Fluoro-3-p-methoxybenzyloxy-1,3-diphenyl-1-propene (CDCl3) δ = 16.7, 20.6, 83.0–83.3 (m), 109.3 (d, J = 6.6 Hz),
(9d). Yellow liquid; IR (neat) 2933, 1692, 1612, 1513, 1494, 119.6, 127.1, 127.6 (d, J = 1.7 Hz), 128.35, 128.41, 128.5, 128.9
1450, 1248, 1173, 1067, 1031, 821, 753, 693 cm−1; HRMS (FAB) (d, J = 7.4 Hz), 130.0, 131.0, 132.8, 133.3, 137.4, 154.1 (d, J =
1
calcd for (M+) C23H21FO2: 348.1526, found 348.1526; H NMR 311.6 Hz) ppm; 19F NMR (CDCl3) δ = −115.56 (dd, J = 37.12,
(CDCl3) δ = 3.82 (s, 3H), 4.60 (d, J = 11.59 Hz, 1H), 4.65 (d, J = 19.48 Hz, 1F) ppm.
11.59 Hz, 1H), 4.96 (d, J = 14.53 Hz, 1H), 5.88 (d, J = 38.94 Hz,
1H), 6.90 (d, J = 7.99 Hz, 2H), 7.24–7.52 (m, 12H) ppm; (neat) 3062, 3031, 1741, 1690, 1602, 1495, 1450, 1371, 1282,
13C NMR (CDCl3) 55.2, 70.3, 78.3–79.0 (m), 1224, 1164, 1023, 975, 755, 694 cm−1; HRMS (FAB) calcd for
(Z)-2-Fluoro-1,3-diphenylallyl acetate (9j). Yellow liquid; IR
δ
=
107.95–108.02 (m), 113.8, 127.3, 127.4 (d, J = 2.5 Hz), 128.4, (M+) C17H15FO2: 270.1056, found 270.1055; 1H NMR (CDCl3)
128.5 (d, J = 5.8 Hz), 128.8 (d, J = 7.4 Hz), 129.5, 129.6, 130.2, δ = 2.19 (s, 3H), 5.82 (d, J = 37.78 Hz, 1H), 6.45 (d, J = 15.69 Hz,
132.8 (d, J = 3.3 Hz), 137.9, 157.8 (d, J = 270.3 Hz), 159.3 ppm; 1H), 7.23–7.50 (m, 10H) ppm; 13C NMR (CDCl3) δ = 21.0–21.1
19F NMR (CDCl3) δ = −114.61 (dd, J = 38.94, 14.53 Hz, 1F) (m), 73.8 (d, J = 29.7 Hz), 109.5–109.6 (m), 127.2, 127.8 (d, J =
ppm.
2.5 Hz), 128.5, 128.6, 128.7, 128.9 (d, J = 7.4 Hz), 132.3 (d, J =
(Z)-2-Fluoro-1,3-diphenyl-3-i-propoxy-1-propene
(9e). This 3.3 Hz), 135.9, 156.0 (d, J = 268.7 Hz), 169.6 ppm; 19F NMR
compound was inseparable from byproducts. HRMS (FAB) (CDCl3) δ = −115.57 (dd, J = 37.78, 15.69 Hz, 1F) ppm.
calcd for (M+) C18H19FO: 270.1420, found 270.1416; 1H NMR
(Z)-2-Fluoro-1,3-diphenylallyl benzoate (9k). Yellow liquid;
(CDCl3) δ = 1.22 (d, J = 6.09 Hz, 3H), 1.28 (d, J = 5.90 Hz, 3H), IR (neat) 3062, 3032, 1725, 1602, 1496, 1450, 1314, 1261, 1176,
3.80 (qq, J = 6.09, 5.90 Hz, 1H), 5.01 (d, J = 14.13 Hz, 1H), 5.85 1094, 1026, 969, 916, 694 cm−1; HRMS (FAB) calcd for (M+)
(d, J = 39.14 Hz, 1H), 7.11–7.51 (m, 10H) ppm; 19F NMR C22H17FO2: 332.1213, found 332.1214; 1H NMR (CDCl3) δ =
(CDCl3) δ = −113.80 (dd, J = 39.14, 14.13 Hz, 1F) ppm.
5.93 (d, J = 37.03 Hz, 1H), 6.70 (d, J = 15.13 Hz, 1H), 7.21–7.59
(2S)-Ethyl 2-((Z)-2-fluoro-1,3-diphenyl-2-propenoxy)propano- (m, 13H), 8.14–8.16 (m, 2H) ppm; 13C NMR (CDCl3) δ = 74.3 (d,
ate (9f). Yellow liquid; dr = 50 : 50; IR (neat) 3026, 2984, 2942, J = 29.8 Hz), 109.77–109.83 (m), 127.2, 127.8 (d, J = 2.5 Hz),
1743, 1496, 1449, 1273, 1204, 1136, 1026, 754, 694 cm−1
;
128.5, 128.7, 128.8, 128.9 (d, J = 7.4 Hz), 129.6, 129.9, 132.3 (d,
HRMS (FAB) calcd for (M+) C20H21FO3: 328.1475, found J = 3.3 Hz), 133.4, 135.9, 156.0 (d, J = 269.5 Hz), 165.2 ppm; the
328.1466; 1H NMR (CDCl3) δ = 1.26 (t, J = 6.99 Hz, 3H) and peak for one carbon could not be identified, because the peak
1.28 (t, J = 6.99 Hz, 3H), 1.45 (d, J = 6.95 Hz, 3H) and 1.53 (d, of aromatic carbon overlapped with other carbons; 19F NMR
J = 6.95 Hz, 3H), 4.00 (q, J = 6.95 Hz, 1H) and 4.33 (q, J = 6.95 (CDCl3) δ = −115.49 (dd, J = 37.03, 15.13 Hz, 1F) ppm.
Hz, 1H), 4.14–4.25 (m, 2H), 5.10 (d, J = 12.41 Hz, 1H) and 5.11
(Z)-N-(2-Fluoro-1,3-diphenylallyl)trifluoroacetamide
(9n).
(d, J = 18.01 Hz, 1H), 5.90 (d, J = 38.18 Hz, 1H) and 5.91 (d, J = White solid; M.P.: 144–145 °C; IR (KBr) 3291, 3066, 1704,
38.74 Hz, 1H), 7.19–7.55 (m, 10H) ppm; 19F NMR (CDCl3) δ = 1603, 1542, 1496, 1451, 1351, 1267, 1179, 938, 900, 833, 755,
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693, 622, 532, 473 cm−1
;
HRMS (FAB) calcd for (M+)
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C17H13F4NO: 323.0933, found 323.0939; 1H NMR (CDCl3) δ =
5.87 (d, J = 37.51 Hz, 1H), 5.88 (dd, J = 18.71, 7.99 Hz, 1H), 6.87
(d, J = 7.99 Hz, 1H), 7.23–7.52 (m, 10H) ppm; 13C NMR (CDCl3)
δ = 55.4 (d, J = 28.1 Hz), 110.0 (d, J = 6.6 Hz), 115.7 (q, J = 287.6
Hz), 126.9, 128.1 (d, J = 2.5 Hz), 128.6, 128.85, 128.90 (d, J = 2.4
Hz), 129.2, 131.8 (d, J = 3.3 Hz), 135.6, 154.8 (d, J = 267.8 Hz),
156.6 (q, J = 38.0 Hz) ppm; 19F NMR (CDCl3) δ = −76.09 (s, 3H),
−116.46 (dd, J = 37.51, 18.71 Hz, 1F) ppm.
(Z)-N-(2-Fluoro-1,3-diphenylallyl)-p-toluenesulfonamide (9o).
White solid; M.P.: 144–145 °C; IR (KBr) 3271, 3031, 2926,
2852, 2345, 1687, 1597, 1495, 1434, 1330, 1159, 1058, 947, 884,
815, 729, 672, 575, 539, 485 cm−1; HRMS (FAB) calcd for (M+)
1
C22H20FNO2S: 381.1199, found 381.1190; H NMR (CDCl3) δ =
2.27 (s, 3H), 5.09 (d, J = 8.39 Hz, 1H), 5.18 (dd, J = 18.97, 8.39
Hz, 1H), 5.61 (d, J = 38.94 Hz, 1H), 7.51 (d, J = 8.19 Hz, 2H),
7.21–7.32 (m, 10H), 7.71 (d, J = 8.19 Hz, 2H) ppm; 13C NMR
(CDCl3) δ = 21.30–21.31 (m), 60.0 (d, J = 28.9 Hz), 109.3 (d, J =
5.0 Hz), 127.0, 127.2, 127.6, 128.3, 128.4, 128.6 (d, J = 7.4 Hz),
128.8, 129.5, 132.1 (d, J = 3.3 Hz), 136.5, 137.1, 143.6, 155.0 (d,
J = 268.6 Hz) ppm; 19F NMR (CDCl3) δ = −116.89 (dd, J = 38.94,
18.97 Hz, 1F) ppm.
(Z)-2-Fluoro-1,3-di-p-tolyl-2-propen-1-ol (9r). Yellow liquid;
IR (neat) 3365, 3025, 2922, 1693, 1613, 1513, 1414, 1274, 1179,
1154, 1136, 1039, 915, 837, 810, 767, 725 cm−1; HRMS (FAB)
calcd for (M+) C17H17FO: 256.1263, found 256.1261; 1H NMR
(CDCl3) δ = 2.22 (d, J = 4.02 Hz, 1H), 2.33 (s, 3H), 2.37 (s, 3H),
5.32 (dd, J = 10.69, 4.20 Hz, 1H), 5.87 (d, J = 38.94 Hz, 1H), 7.13
(d, J = 8.09 Hz, 2H), 7.21 (d, J = 8.09 Hz, 2H), 7.38 (d, J = 8.09
Hz, 2H), 7.40 (d, J = 8.09 Hz, 2H) ppm; 13C NMR (CDCl3) δ =
21.1, 21.2, 73.0 (d, J = 33.0 Hz), 106.65–106.74 (m), 126.7, 128.7
(d, J = 6.6 Hz), 129.1, 129.3, 129.9 (d, J = 2.5 Hz), 136.5, 137.2
(d, J = 2.5 Hz), 138.3, 158.8 (d, J = 267.0 Hz) ppm; 19F NMR
(CDCl3) δ = −116.54 (dd, J = 38.94, 10.69 Hz, 1F) ppm.
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