(NHC)AgCl catalyzed bromofluorocyclopropanation of alkenes with CFBr2CO2Na

Article abstract of DOI:10.1016/j.jfluchem.2018.02.001

An effective method for bromofluorocyclopropanation of electron-rich (aryl substituted), electron-neutral (monoalkyl substituted), electron-poor (haloalkenes, allylic esters, α,β-unsaturated esters) and acid/base sensitive silyl- and boronyl substituted a

Full text of DOI:10.1016/j.jfluchem.2018.02.001

Accepted Manuscript
Title: (NHC)AgCl catalyzed bromofluorocyclopropanation of
alkenes with CFBr2CO2Na
Authors: Anastasia A. Andrianova, Yulia D. Maslova, Maxim
A. Novikov, Sergei E. Semenov, Oleg M. Nefedov
PII:
S0022-1139(17)30463-3
DOI:
Reference:
https://doi.org/10.1016/j.jfluchem.2018.02.001
FLUOR 9115
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Received date:
Revised date:
Accepted date:
30-10-2017
27-1-2018
5-2-2018
Please cite this article as: Andrianova AA, Maslova YD, Novikov MA,
Semenov SE, Nefedov OM, (NHC)AgCl catalyzed bromofluorocyclopropanation
of alkenes with CFBr2CO2Na, Journal of Fluorine Chemistry (2010),
https://doi.org/10.1016/j.jfluchem.2018.02.001
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1
(NHC)AgCl catalyzed bromofluorocyclopropanation of alkenes with
CFBr2CO2Na
Anastasia A. Andrianovaa, Yulia D. Maslovaa, Maxim A. Novikova,b*, and Sergei E. Semenova,
and Oleg M. Nefedovb
a
Moscow Chemical Lyceum 1303, Moscow South-Eastern School named after V.I. Chuikov, 4
Tamozhennyy pr-d, 111033 Moscow, Russian Federation
b
N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky
prosp., 119991 Moscow, Russian Federation
Fax: +7499 135 63 90; e-mail: manovikov@ioc.ac.ru
Highlights
 Bromofluorocyclopropanation of various alkenes with CFBr2CO2Na catalyzed by
(NHC)AgCl
 Electron-rich and electron-poor alkenes give good to excellent yields
 ,-Unsaturated esters can be effectively cyclopropanated
 Silyl- and boronyl substituted gem-bromofluorocyclopropanes can be prepared
The Graphical Abstract — Pictogram
(For the Web only)

2
(For the Print)
The Graphical Abstract — Synopsis
An effective method for bromofluorocyclopropanation of various alkenes with
CFBr2CO2Na and catalytic (IPr)AgCl or (SIPr)AgCl was developed.
Highlights
 Bromofluorocyclopropanation of various alkenes with CFBr2CO2Na catalyzed by
(NHC)AgCl
 Electron-rich and electron-poor alkenes give good to excellent yields
 ,-Unsaturated esters can be effectively cyclopropanated
 Silyl- and boronyl substituted gem-bromofluorocyclopropanes can be prepared
Abstract
An effective method for bromofluorocyclopropanation of electron-rich (aryl substituted),
electron-neutral (monoalkyl substituted), electron-poor (haloalkenes, allylic esters, ,-
unsaturated esters) and acid/base sensitive silyl- and boronyl substituted alkenes with
CFBr2CO2Na and catalytic (IPr)AgCl or (SIPr)AgCl was developed.
Keywords: fluorocyclopropanes, fluorocarbenes, silver catalysis, catalytic cyclopropanation
1. Introduction
Fluorinated cyclopropane ring for a long time has been recognized as a structural fragment
with a broad scope of applications [1]. Fluorocyclopropanes can be found in a wide range of
biologically active compounds and bioisosters of natural products developed in past decades [2].
Fluorocyclopropanes have also wide synthetic applications, as they can undergo ring-
opening transformations leading to organofluorine compounds of different classes. For these
purposes, gem-fluorohalocyclopropanes (halogen = fluorine, chlorine, bromine) were found to be
the most attractive, as they can be prepared by cyclopropanation of alkenes with
fluorohalocarbenes (:CF2, :CFCl; :CFBr) [3]. Cyclopropyl-allylic ring-opening rearrangements
of gem-fluorohalocyclopropanes are useful for synthesis of fluorobenzenes [4],

3
fluoronaphthalenes [5], fluorodienes [6] and fluoroallylic compounds [7], as well as for -fluoro-
or ,-difluoro substituted carbonyl compounds [8]. Rearrangements of vinyl substituted gem-
fluorohalocyclopropanes are effective for synthesis of fluorinated cyclopentenes [9]. Moreover,
fluorocyclopropanes can be used for preparation of various types of heterocylic compounds like
pirimidines, oxazoles, etc. [10].
Many efficient :CF2 sources were developed since 2000s, e.g. FSO2CF2CO2R (R = SiMe3,
–
Me) [11], CF2X-SiMe3 (X = F, Cl, Br) [12], BrCF2CO2Na [13], Ph3P+-CF2-CO2 [14]. On the
contrary, sources of :CFCl and :CFBr are still limited mostly to CHCl2F and CHBr2F [3,7,10].
Other reported reagents include CFX2CO2R (X = Cl, Br, R = Me, Et) [15], CFCl2C(O)CFCl2
[16], which form :CFX in the presence of a base like NaOMe. Also :CFCl can be generated by
reduction of CCl3F with TiCl4/LiAlH4 [17]. However, all these reagents suffer many
disadvantages, and therefore did not find broad synthetic applications. Thus, cyclopropanation
with CHCl2F or CHBr2F under Makosza’s PTC conditions (i.e. conc. NaOH or KOH in the
presence of a phase transfer catalyst — quaternary ammonium salts, crown ethers, etc. [3]) is
usually a method of choice. But these conditions work well only for electron-rich alkenes, and
even monoalkyl substituted ones give poor results.
Many stoichiometric organometallic reagents for fluorohalocyclopropanation are known.
They include various trihalomethyl mercury derivatives (PhHgCF3 [18a], Hg(CF3)2 [18b,c],
PhHgCCl2F [18d], PhHgCBr2F [18e]), as well as Zn(CF3)2 [19] and Cd(CF3)2 [20]. But no
examples of catalytic use of any of these reagents were reported. The only report of metal
catalyzed fluorocyclopropanation published to date is difluorocyclopropanation of silyl enolates
with FSO2CF2CO2SiMe3 in the presence of NiII pincer complexes [9b].
In the current work, we report a general method of (NHC)AgCl catalyzed
bromofluorocyclopropanation of various alkenes using CFBr2CO2Na as a carbene source.
2. Results and Discussion
For preliminary experiments on cyclopropanation with CFBr2CO2Na, classical reaction
conditions were chosen, i.e. slow addition of an excess of the salt into preheated solution of an
alkene in diglyme (table 1, entry 1). Under this conditions -boronyl styrene 1a was
cyclopropanated in only 29% yield. The main fluorinated side products were found to be
CHBr2F and CBr3F. As soon as, CFBr2CO2Na decomposes rapidly in diglyme, the reaction in it
showed almost no sensitivity to different additives (table 1, entries 2–6).

4
In DCE CFBr2CO2Na is not soluble and decompose at elevated temperatures very slowly
(table 1, entry 7). Screening of additives in this solvent (see table 1, entries 8–13) revealed that
the cyclopropanation can be effectively catalyzed by silver (I) NHC-complexes — (IPr)AgCl and
(SIPr)AgCl (table 1, entries 12, 13). Other phase transfer catalysts (TEBAC, 18-crown-6)
resulted in too fast decomposition of CFBr2CO2Na and poor yields of cyclopropane 2a. Other
solvents (toluene, THF, dioxane) were also tested, but the yields were low.
Plausible mechanism of the catalysis should involve transferring of dibromofluoroacetate
into reaction medium presumably via formation of soluble (NHC)AgO2CCFBr2 [21]. These
intermediate complexes presumably decompose at elevated temperatures forming :CFBr.
Involvement of free carbene in a cyclopropanation step can be confirmed by the same syn/anti
ratios of gem-bromofluorocyclopropanes formed using both CFBr2CO2Na/(IPr)AgCl and
CHBr2F/NaOH/TEBAC methods [22]. However, detailed investigation of the reaction
mechanism and structures of silver complexes involved in it is currently underway in our
laboratory.
Next, substrate scope of the catalytic cyclopropanation was studied (see scheme 1). Good
to excellent yields were obtained not only for aryl substituted alkenes (1b,1c), but also for
monoalkyl substituted alkenes (1f), haloalkenes (1d,1e), allylic esters (1j,1k,1l) using as low as 2
equiv. of CFBr2CO2Na and 2 mol.% of (IPr)AgCl. Moderate yields were obtained even for ,-
unsaturated esters — benzyl acrylate 1m and methyl cinnamate 1n, but larger excess of
CFBr2CO2Na (8 equiv.) was required. Such unexpectedly high reactivity of usually inactive
alkenes can be attributed to higher reaction temperatures then under PTC conditions [23], and/or
to a special influence of silver catalyst. The absence of strong acids and bases in the reaction
mixture allowed us to obtain (pinacol)boronyl- (2a,2g) and trimethylsilyl (2h,2i) substituted
cyclopropanes in moderate to good yields. Also, it should be noted that our catalytic
cyclopropanation proceed with complete retention of a double bond configuration giving only
trans-isomeric cyclopropanes 2g, 2i, 2j and 2n from corresponding trans-alkenes [24].
Attempts to cyclopropanate fluoroallyl imide 1o, amine 1p, enamine 1q and silyl enolate
1r were unsuccessful and led to formation of complex product mixtures (fig. 1). While influence
amino- and imido groups in 1o,p is unclear, the issues of alkenes 1q,r are easy to rationalize.
gem-Bromofluorocyclopropanes formed from 1q,r, contain +M electron-donating oxygen- and
nitrogen substituents that are known to accelerate cyclopropyl-to-allyl type ring-opening
rearrangements significantly [3,25]. Forming ring-opening products could undergo further
reactions and polymerize under the reaction conditions leading to complex mixtures.

5
The developed method is easily scalable. It was demonstrated by cyclopropanation of 20
mmol of oct-1-ene 1s affording cyclopropane 2s in 85% yield after distillation (scheme 2).
3. Conclusions
In
summary,
a
new
method
with
unusually
high
reactivity
for
bromofluorocyclopropanation of various alkenes with CFBr2CO2Na and catalytic (IPr)AgCl or
(SIPr)AgCl was developed. Using this method, good to excellent yields can be obtained not only
with electron-rich alkenes (aryl substituted), but also with electron-neutral (monoalkyl
substituted) and electron-poor alkenes (haloalkenes, allylic esters, ,-unsaturated esters).
Absence of strong acids and bases in the reaction medium allows obtaining by this method
acid/base sensitive silyl- and boronyl substituted gem-bromofluorocyclopropanes. Free carbene
was presumed to be involved in the reaction mechanism formed by decomposition of
(NHC)AgO2CCFBr2 complexes. Detailed mechanistic investigations are currently underway in
our laboratory.
4. Experimental
4.1. General information
All reagents were purchased from Acros, Aldrich, ABCR or Alfa Aesar and used without
further purification. Diglyme was distilled over LiAlH4 under reduced pressure and stored over
4A Linde type molecular sieves. DCE was distilled over P2O5 and stored over 4A Linde type
molecular sieves. (IPr)AgCl and (SIPr)AgCl were obtained by published procedure [26]. 1H, 19F,
13C NMR were recorded on Bruker AVANCE II 300 (300.1, 282.4. MHz and 75.5 MHz,
1
respectively) or Bruker AMX-400 (400.1 MHz for H and 100.4 MHz for 13C) in CDCl3
1
containing TMS as an internal standard. Chemical shifts are reported for H relative to internal
TMS ( = 0.00 ppm), for 13C relative to CDCl3 ( = 77.1 ppm), for 19F relative to internal C6F6 (
= –162.2 ppm). Chemical shifts for CFBr2CO2Na are reported in D2O: for 19F relative to external
CFCl3 ( = 0.0 ppm), for 13C relative to external TMS ( = 0.0 ppm). 1H, 13C and 19F homo- and
heteronuclear correlations were recorded on Bruker AVANCE II 300. GC/MS analysis was
performed on gas chromatographer Chromatec Crystal 5000.2 with Thermo DSQ II (EI, 70 eV,
200°C) mass-detector. HRMS were recorded on Bruker micrOTOF equipment using electro-
spray ionization. Elemental analysis was made in laboratory of microanalysis IOC RAS on
Perkin-Elmer Series II 2400 CHN Analyzer.

6
4.2. Synthesis of CFBr2CO2Na
CFBr2CO2Na was prepared by hydrolysis of CFBr2CO2Me derived from fluorination of
CBr3CO2Me with SbF3. However, CFBr2CO2H and CFBr2CO2Et are now commercially
available.
To a stirred mixture of 44.8 g (144 mmol) of CBr3CO2Me, 8.8 g (49 mmol) of SbF3 and
5.7 g (36 mmol) of Br2 were added. The reaction mixture was stirred at 120°C for 4 hours and
diluted with petroleum ether and aqueous Na2SO3. The organic layer was separated, dried with
MgSO4, concentrated on a rotary evaporator (50 mmHg, 30°C) and the residue was distilled
under reduced pressure affording 14.3 g (57 mmol) of CFBr2CO2Me as a colorless liquid (40%
yield, bp 75–77°C / 45 mmHg). It was slowly added to a solution of 2.25 g (56 mmol) of NaOH
in 60 mL of abs. EtOH with cooling on a water bath. The reaction mixture was stirred at r.t. for 1
hour, then concentrated on a rotary evaporator (30°C). The solid residue was dried under high
vacuum (less than 0.1 mmHg) at room temperature with stirring on a magnetic stirrer for 5
hours. 11.2 g of colorless solids were obtained (77% yield). The purity was estimated to be 90%
by 19F NMR using CF3CO2Na as an internal standard. CFBr2CO2Na isn’t deliquescent and is
easy to handle. However, CFBr2CO2Na was additionally dried prior to use under high vacuum in
order to ensure complete removal of water and ethanol.
13
19F NMR (282.4 MHz, D2O) : –55.0 (s). C NMR (75.5 MHz, D2O) : 89.4 (d, CFBr2, J =
328 Hz), 167.6 (d, C=O, J = 21.6 Hz).
4.3. (IPr)AgCl-catalyzed cyclopropanation (general procedure)
A 10-mL Schlenk tube was dried under high vacuum (less than 0.1 mmHg) with heating by
heatgun for 5 min (a round-bottom flask equipped with a tubing adaptor can be used instead).
Then, it was opened to air and charged with 2.0 mmol of CBr2FCO2Na and 0.040 mmol of
(IPr)AgCl. The mixture was dried under high vacuum (less than 0.1 mmHg) at room temperature
for 1 hour. Next, in a stream of argon, 1.0 mmol of alkene and 1.0 mL of DCE were added and
the reaction mixture was stirred for 5–48 hours at 70–75°C. The reaction progress was monitored
by GC. After the reaction complete, it was evaporated with 0.40 g of Celite and the product was
isolated by column chromatography on 5 g of silica (40–63 m).

7
4.3.1.
2-(2-Bromo-2-fluoro-1-phenylcyclopropyl)-4,4,5,5-tetramethyl-1,3,2-
dioxaborolane (2a)
Obtained by the general procedure (the reaction time — 10 hours) on 5.0 mmol scale after
column chromatography (n-hexane/Et2O, 10/1) as a yellow solid (1.305 g, 76% yield, syn-/anti-
= 49/51).
1H NMR (300.1 MHz, CDCl3) : 1.17 (s, 6H, 2CH3), 1.19 (s, 6H, 2CH3), 1.22 (s, 6H, 2CH3),
1.24 (s, 6H, 2CH3), 1.74 (dd, 1H, CH2 (trans- to F), anti-2a, J = 6.8, 5.6 Hz), 1.88 (dd, 1H,
CH2 (cis- to F), syn-2a, J = 16.7, 6.9 Hz), 2.00 (dd, 1H, CH2 (trans- to F), syn-2a, J = 9.1, 6.9
Hz), 2.29 (dd, 1H, CH2 (cis- to F), anti-2a, J = 15.2, 6.8 Hz), 7.18–7.36 (m, 5H, arom., both
isomers). 19F NMR (282.4 MHz, CDCl3) : –123.9 (dd, anti-2a, J = 15.2, 5.5 Hz), –130.2 (dd,
13
syn-2a, J = 16.7, 9.1 Hz). C NMR (100.6 MHz, CDCl3) : 24.5 (s, 2CH3), 24.7 (s, 2CH3),
24.8 (s, 2CH3), 24.9 (s, 2CH3), 25.7 (d, CH2-cycloprop., J = 6.3 Hz), 25.8 (d, CH2-cycloprop.,
J = 6.9 Hz), 83.5 (d, CFBr-cycloprop., J = 304 Hz), 84.6 (s, 2C-pin), 84.7 (s, 2C-pin), 89.1 (d,
CFBr-cycloprop., J = 300 Hz), 126.7 (s, CH-arom.), 126.8 (s, CH-arom.), 128.1 (s, CH-
arom.), 128.3 (s, CH-arom.), 129.4 (d, CH-arom., J = 2.0 Hz), 129.5 (s, CH-arom.), 136.2 (d,
C-arom., J = 4.1 Hz), 139.0 (s, C-arom.). MS (EI, 70 eV) m/z 339/340/341/342 ([M+],
1/5/1/5), 242 (7), 214 (16), 161 (70), 141 (63), 133 (63), 115 (100), 101 (78), 89 (27), 83 (56),
+
77 (14), 59 (77). HRMS (ESI), calc. for C15H19BBrFO2: m/z 358.0986 [M+NH4 ], 363.0540
+
[M+Na+]. Found: m/z 358.0979 [M+NH4 ], 363.0534 [M+Na+].
4.3.2.
2-Bromo-2-fluoro-1-phenylcyclopropane (2b)
Obtained by the general procedure (the reaction time — 5 hours) after column
chromatography (n-hexane/benzene, 10/1) as a colorless oil (212.3 mg, 99% yield, syn-/anti- =
46/54). During rotary evaporation and further drying 10 mmHg and 30°C were used. NMR data
are fully consistent with previously published [27].
1H NMR (300.1 MHz, CDCl3) : 1.62–1.71 (m, 1H, anti-2b), 1.76–1.92 (m, 2H, syn-2b), 2.01
(ddd, 1H, anti-2b, J = 17.0, 11.6, 7.9 Hz), 2.70–2.83 (m, 1H, CH(Ph), both isomers), 7.17–
19
7.37 (m, 5H, arom.). F NMR (282.4 MHz, CDCl3) : –125.3 (ddd, syn-2b, J = 18.2, 17.1,
7.3 Hz), –146.7 (ddd, anti-2b, J = 17.0, 9.0, 2.7 Hz). 13C NMR (75.5 MHz, CDCl3) : 22.0 (d,
CH2, J = 10.6 Hz), 22.7 (d, CH2, J = 10.4 Hz), 30.7 (d, CH(Ph), J = 11.0 Hz), 33.3 (d,
CH(Ph), J = 10.8 Hz), 80.5 (d, CFBr, J = 302.2 Hz), 86.1 (d, CFBr, J = 301.3 Hz), 127.4 (s,
CH-arom.), 127.5 (s, CH-arom.), 128.4 (s, 2CH-arom.), 128.5 (s, CH-arom.), 128.6 (d, CH-
arom., J = 2.1 Hz), 133.6 (s, C-arom.), 135.5 (s, C-arom.).

8
4.3.3.
2-Bromo-2-fluoro-1,1-diphenylcyclopropane (2c)
Obtained by the general procedure (the reaction time — 10 hours) after column
chromatography (n-hexane/benzene, 10/1) as a colorless solids (239.6 mg, 82% yield, mp 79–
80°C). NMR data are fully consistent with previously published [28].
1H NMR (300.1 MHz, CDCl3) : 2.15 (dd, 1H, CH2 (trans- to F), J = 8.1, 7.7 Hz), 2.26 (dd,
1H, CH2 (cis- to F), J = 17.6, 7.7 Hz), 7.16–7.50 (m, 10H, 2Ph). 19F NMR (282.4 MHz,
13
CDCl3) : –128.1 (dd, J = 17.6, 8.1 Hz). C NMR (75.5 MHz, CDCl3) : 29.2 (d, CH2, J =
9.9 Hz), 43.2 (d, C(Ph)2, J = 10.0 Hz), 86.7 (d, CFBr, J = 305 Hz), 127.4 (s, CH-arom.), 128.5
(s, CH-arom.), 128.7 (s, CH-arom.), 128.9 (d, CH-arom., J = 1.5 Hz), 129.4 (s, CH-arom.),
139.2 (d, C-arom., J = 2.6 Hz), 141.3 (d, C-arom., J = 2.5 Hz).
4.3.4.
2-Bromo-1,2-difluoro-1-phenylcyclopropane (2d)
Obtained by the general procedure (the reaction time — 18 hours) after column
chromatography (n-hexane/benzene, 10/1) as a colorless oil (203.2 mg, 87% yield, syn-/anti- =
48/52). During rotary evaporation and further drying 10 mmHg and 30°C were used.
1H NMR (300.1 MHz, CDCl3)  1.96–2.16 (m, 1H, cycloprop.), 2.19–2.42 (m, 1H,
cycloprop.), 7.36–7.50 (m, 5H, arom.). 1H{19F} NMR (300.1 MHz, CDCl3)  2.05 (d, 1H,
anti-2d, J = 10.4 Hz), 2.09 (d, 1H, syn-2d, J = 10.6 Hz), 2.30 (d, 1H, anti-2d, J = 10.6 Hz),
2.33 (d, 1H, syn-2d, J = 10.4 Hz), 7.36–7.50 (m, 5H, arom.). 19F NMR (282.4 MHz CDCl3) 
–140.1 (dd, 1F, CFBr, syn-2d, J = 20.1, 10.1 Hz), –145.5 (ddd, 1F, CFBr, anti-2d, J = 22.1,
10.9, 6.5 Hz), –160.6 (dd, 1F, CFPh, syn-2d, J = 20.4, 11.1 Hz), –176.7 (ddd, 1F, CFPh, anti-
13
2d, J = 24.6, 13.1, 6.5 Hz). C NMR (100.6 МHz, CDCl3) : 26.8 (dd, CH2, J = 12.3, 10.4
Hz), 28.3 (dd, CH2, J = 13.3, 11.6 Hz), 79.5 (dd, CFPh, J = 234, 11.8 Hz), 80.4 (dd, CFPh, J
= 235, 9.2 Hz), 81.5 (dd, CFBr, J = 306 Hz, 17.0 Hz), 81.7 (dd, CFBr, J = 313, 13.2 Hz),
127.3 (dd, CH-arom., J = 5.2, 1.0 Hz), 127.7 (dd, CH-arom., J = 4.5, 1.0 Hz), 128.6 (s, CH-
arom.), 128.7 (s, CH-arom.), 129.6 (d, CH-arom., J = 2.0 Hz), 129.8 (d, CH-arom., J = 2.3
Hz), 131.0 (d, C-arom., J = 20.7 Hz), 132.9 (dd, C-arom., J = 20.3, 2.0 Hz). MS (EI, 70 eV)
m/z 232/234 ([M+], 0.5/0.5), 153 (70), 133 (100), 127 (6), 107 (10), 81 (6), 77 (5), 63 (6), 57
(6), 51 (8). Anal.: calcd. for C9H7BrF2: C, 46.38%; H, 3.03%. Found: C, 46.13%; H, 3.15%.

9
4.3.5.
1,2-Dibromo-2-fluoro-1-phenylcyclopropane (2e)
Obtained by the general procedure (the reaction time — 18 hours) after column
chromatography (n-hexane/benzene, 10/1) as a colorless oil (209.0 mg, 71% yield, syn-/anti- =
43/57).
1H NMR (300.1 MHz, CDCl3) : 1.94 (dd, 1H, syn-2e, J = 9.5, 9.4 Hz), 2.17–2.30 (m, 2H,
19
anti-2e), 2.38 (dd, 1H, syn-2e, J = 18.5, 9.5 Hz), 7.27–7.53 (m, 5H, arom.). F NMR (282.4
MHz, CDCl3) : –125.4 (dd, anti-2e, J = 13.7, 9.5 Hz), –129.6 (dd, syn-2e, J = 18.5, 9.4 Hz).
13C NMR (75.5 MHz, CDCl3) : 31.9 (d, CH2-cycloprop., J = 10.9 Hz), 32.7 (d, CH2-
cycloprop., J = 11.0 Hz), 38.3 (d, C-cycloprop., J = 11.0 Hz), 39.3 (d, C-cycloprop., J = 11.8
Hz), 81.3 (d, CFBr, J = 205.7 Hz), 85.4 (d, CFBr, J = 201.4 Hz), 128.8 (s, CH-arom.), 128.9
(s, CH-arom.), 129.2 (s, CH-arom.), 129.3 (s, CH-arom.), 136.6 (s, C-arom.), 139.1 (s, C-
arom.). MS (EI, 70 eV) m/z 292/294/296 ([M+], 0.1/0.2/0.1), 213/215 ([M–Br]+, 18/18),
193/195 (2/2), 134 (38), 133 (100), 107 (8), 89 (6), 77 (7), 67 (12), 63 (9), 57 (5), 51 (6).
Anal.: calcd. for C9H7Br2F: C, 36.77%; H, 2.40%. Found: C, 36.86%; H, 2.56%.
4.3.6.
2-Bromo-2-fluoro-1-(1-naphthylmethyl)cyclopropane (2f)
Obtained by the general procedure (the reaction time — 18 hours) after column
chromatography (n-hexane/benzene, 10/1) as a colorless oil (229.3 mg, 82% yield, syn-/anti- =
46/54).
1H NMR (300.1 MHz, CDCl3) : 1.05–1.15 (m, 1H, syn-2f), 1.24–1.39 (m, 1H, anti-2f),
1.42–1.53 (m, 1H, anti-2f), 1.64–1.78 (m, 1H, syn-2f), 1.82–2.03 (m, 1H, both isomers), 3.06
(ddd, 1H, CH2-naphth., syn-2f, J = 15.7, 7.2, 2.8 Hz), 3.19 (ddd, 1H, CH2-naphth., anti-2f, J =
15.7, 7.1, 1.5 Hz), 7.37–7.55 (m, 4H, naphth.), 7.66–7.82 (m, 1H, naphth.), 7.82–7.89 (m, 1H,
naphth.), 7.96–8.03 (m, 1H, naphth.). 19F NMR (282.4 MHz, CDCl3) : –127.0 (dddd, syn-2f,
13
J = 19.8, 17.1, 7.1, 2.7 Hz), –148.4 (dd, J = 17.6, 7.8 Hz). C NMR (75.5 MHz, CDCl3) :
22.7 (d, CH2-cycloprop., syn-2f, J = 10.2 Hz), 23.1 (d, CH2-cycloprop., anti-2f, J = 10.8 Hz),
25.6 (d, CH-cycloprop., syn-2f, J = 9.6 Hz), 28.8 (d, CH-cycloprop., anti-2f, J = 10.6 Hz),
29.9 (d, CH2, anti-2f, J = 5.7 Hz), 34.2 (d, CH2, syn-2f, J = 1.1 Hz), 82.2 (d, CFBr-cycloprop.,
anti-2f, J = 301.5 Hz), 87.4 (d, CFBr-cycloprop., syn-2f, J = 298.9 Hz), 123.4 (s, CH-arom.),
123.4 (s, CH-arom.), 125.7–125.8 (m, nCH-arom.), 126.2 (s, CH-arom.), 127.3 (s, CH-arom.),
127.4 (s, CH-arom.), 129.0 (s, CH-arom.), 129.0 (s, CH-arom.), 131.9 (s, C-arom.), 133.9 (s,
C-arom.), 133.9 (s, C-arom.), 135.1 (s, C-arom.), 135.2 (s, C-arom.), 135.6 (s, C-arom.). MS
(EI, 70 eV) m/z 278/280 ([M+], 13/13), 199 (63), 183 (21), 179 (100), 165 (26), 153 (91), 141

10
(63), 126 (15), 115 (45), 98 (7), 89 (11), 76 (16), 63 (13), 51 (8). Anal.: calcd. for C14H12BrF:
C, 60.24%; H, 4.33%. Found: C, 60.12%; H, 4.35%.
4.3.7.
2-(2-Bromo-2-fluoro-trans-3-phenylcyclopropyl)-4,4,5,5-tetramethyl-1,3,2-
dioxaborolane (2g)
Obtained by the general procedure (the reaction time — 5 hours) on 5.0 mmol scale. Due
to high instability of 2g on silica, another isolation procedure was used: the reaction mixture was
evaporated with 3 g of Celite. Resulting solids were loaded on a top of a short plug of Celite and
the product was eluted with n-hexane/Et2O (ca. 100 mL). Evaporation and drying under high
vacuum afforded an orange viscous oil (1.552 g, 91% yield, syn-/anti- = 43/57).
1H NMR (300.1 MHz, CDCl3) : 1.21–1.53 (m, 12H (pin) + 1H (CH-cycloprop.)), 2.93 (dd,
1H, CH(Ph), J = 9.9, 3.4 Hz), 3.00 (dd, 1H, CH(Ph), J = 16.6, 10.0 Hz), 7.16-7.35 (m, 5H,
arom.). 19F NMR (282.4 MHz, CDCl3) : –123.2 (dd, syn-2g, J = 16.6, 8.4 Hz), -133.86 (dd,
anti-2g, J = 22.0, 3.3 Hz). 13C NMR (75.5 MHz, CDCl3) : 24.7 (s, CH3), 24.7 (s, CH3), 25.0
(s, CH3), 25.1 (s, CH3), 34.8 (d, CH(Ph), J = 10.4 Hz), 36.7 (d, CH(Ph), J = 9.5 Hz), 83.9 (d,
CFBr, J = 303 Hz), 84.4 (s, C(CH3)2), 84.6 (s, C(CH3)2), 88.6 (d, CFBr, J = 305 Hz), 127.3 (s,
CH-arom.), 127.4 (s, CH-arom.), 128.2 (d, CH-arom., J = 1.4 Hz), 128.3 (s, CH-arom.), 128.4
(d, CH-arom., J = 2.1 Hz), 128.4 (s, CH-arom.), 133.9 (d, C-arom., J = 1.4 Hz), 135.7 (s, C-
arom.). MS (EI, 70 eV) m/z 339/340/341/342 ([M+], 0.4/1/0.5/1), 261 (46), 224 (6), 197 (8),
161 (26), 141 (33), 131 (25), 115 (80), 101 (45), 83 (100), 59 (28), 57 (29), 55 (25). HRMS
(ESI), calc. for C15H19BBrFO2: m/z 363.0540 [M+Na+]. Found: m/z 363.0545 [M+Na+].
4.3.8.
2-(2-Bromo-2-fluoro-1-phenylcyclopropyl)trimethylsilane (2h)
Obtained by the general procedure (the reaction time — 18 hours) after column
chromatography (n-hexane) as a colorless oil (179 mg, 62% yield, syn-/anti- = 33/67).
1H NMR (300.1 MHz, CDCl3) : 0.03 (d, 9H, SiMe3, anti-2h, J = 1.0 Hz), 0.06 (s, 9H, SiMe3,
syn-2h), 1.58 (dd, 1H, CH2-cycloprop. (trans- to F), anti-2h, J = 6.5, 4.0 Hz), 1.69–1.84 (m,
2H, CH2-cycloprop., syn-2h), 2.00 (dd, 1H, CH2-cycloprop. (cis- to F), anti-2h, J = 12.8, 6.5
Hz, 1H), 6.92–7.36 (m, 5H, arom.). 19F NMR (282.4 MHz, CDCl3) : –120.8 (dd, syn-2h, J =
13
16.2, 7.8 Hz), -122.26 (dd, anti-2h, J = 12.7, 2.8 Hz). C NMR (75.5 MHz, CDCl3) : –2.0
(s, SiMe3, syn-2h), -1.6 (d, SiMe3, anti-2h, J = 1.6 Hz), 26.4 (d, CH2-cycloprop., syn-2h, J =
10.3 Hz), 26.6 (d, CH2-cycloprop., anti-2h, J = 9.5 Hz), 32.3 (d, C(Ph)-cycloprop., syn-2h, J

11
= 6.5 Hz), 32.4 (d, C(Ph)-cycloprop., anti-2h, J = 19.2 Hz), 85.2 (d, CFBr-cycloprop., syn-2h,
J = 301 Hz), 89.3 (d, CFBr-cycloprop., anti-2h, J = 297 Hz), 126.3 (s, CH-arom.), 126.3 (s,
CH-arom.), 128.2 (s, CH-arom.), 128.3 (s, CH-arom.), 129.5 (s, CH-arom.), 138.3 (d, C-
arom., syn-2h, J = 5.9 Hz), 141.2 (s, C-arom., anti-2h). MS (EI, 70 eV) m/z 286/288 ([M+],
9/9), 207 (15), 133 (38), 115 (100), 77 (54), 73 (66). Anal.: calcd. for C12H16BrFSi: C,
50.18%; H, 5.61%. Found: C, 50.00%; H, 5.05%.
4.3.9.
(2-Bromo-2-fluoro-trans-3-phenylcyclopropyl)trimethylsilane (2i)
Obtained by the general procedure (the reaction time — 18 hours) on 3.0 mmol scale after
column chromatography (n-hexane) as a colorless oil (673.6 mg, 75% yield, syn-/anti- = 70/30).
1H NMR (300.1 MHz, CDCl3) : 0.18 (d, 9H, SiMe3, anti-2i, J = 0.7 Hz), 0.19 (s, 9H, SiMe3,
syn-2i), 1.11 (dd, 1H, CH(TMS), anti-2i, J = 13.0, 10.8 Hz), 1.15 (dd, 1H, CH(TMS), syn-2i,
19
J = 24.7, 10.6 Hz), 2.57–2.67 (m, 1H, CH(Ph), both isomers), 7.16–7.37 (m, 5H, arom.). F
NMR (282.4 MHz, CDCl3) : –121.1 (dd, anti-2i, J = 13.9, 13.9 Hz), –127.8 (d, syn-2i, J =
24.7 Hz). 13C NMR (75.5 MHz, CDCl3) : –1.7 (s, SiMe3, syn-2i), –1.3 (d, SiMe3, anti-2i, J =
1.0 Hz), 23.0 (d, CH(TMS), syn-2i, J = 2.9 Hz), 24.9 (d, CH(TMS), anti-2i, J = 18.6 Hz), 33.7
(d, CH(Ph), anti-2i, J = 10.0 Hz), 36.5 (d, CH(Ph), syn-2i, J = 10.9 Hz), 86.0 (d, CFBr, syn-2i,
J = 303 Hz), 89.8 (d, CFBr, anti-2i, J = 301 Hz), 127.3 (s, CH-arom., syn-2i), 127.4 (s, CH-
arom., anti-2i), 128.3 (d, CH-arom., syn-2i, J = 1.3 Hz), 128.3 (s, CH-arom., anti-2i), 128.5
(s, CH-arom., syn-2i), 128.5 (d, CH-arom., anti-2i, J = 2.3 Hz), 134.9 (d, C-arom., syn-2i, J =
1.1 Hz), 136.7 (d, C-arom., anti-2i, J = 1.4 Hz). MS (EI, 70 eV) m/z 207 (19), 134 (36), 133
(36), 115 (100), 77 (17), 73 (58). Anal.: calcd. for C12H16BrFSi: C, 50.18%; H, 5.61%. Found:
C, 49.90%; H, 5.56%.
4.3.10.
(2-Bromo-2-fluoro-trans-3-phenylcyclopropyl)methyl acetate (2j)
Obtained by the general procedure (the reaction time — 18 hours) after column
chromatography (n-hexane/EtOAc, 10/1) as a colorless oil (242.2 mg, 84% yield, syn-/anti- =
28/72).
1H NMR (300.1 MHz, CDCl3) : 2.10 (s, 3H, CH3, both isomers), 2.35 – 2.02 (m, 1H,
CH(CH2OAc), both isomers), 2.60 (dd, 1H, CH(Ph), anti-2j, J = 8.2, 3.4 Hz), 2.66 (dd, 1H,
CH(Ph), syn-2j, J = 20.0, 8.3 Hz, 1H), 4.17–4.49 (m, 2H, CH2OAc, both isomers), 7.18–7.38
(m, 5H, arom.). 19F NMR (282.4 MHz, CDCl3) : –139.0 (br. d, syn-2j, J = 20.7 Hz), –139.8

12
13
(br. d, anti-2j, J = 19.1 Hz). C NMR (75.5 MHz, CDCl3) : 20.9 (s, CH3, both isomers),
29.9 (d, CH-cycloprop., anti-2j, J = 10.2 Hz), 32.2 (d, CH-cycloprop., syn-2j, J = 10.2 Hz),
35.1 (d, CH-cycloprop., syn-2j, J = 10.8 Hz), 37.7 (d, CH-cycloprop., anti-2j, J = 10.5 Hz),
61.2 (d, CH2OAc, syn-2j, J = 7.3 Hz), 64.9 (s, CH2OAc, anti-2j), 84.7 (d, CFBr, anti-2j, J =
303 Hz), 86.7 (d, CFBr, syn-2j, J = 305 Hz), 127.7 (s, CH-arom.), 127.8 (s, CH-arom.), 128.4
(s, CH-arom.), 128.5 (s, CH-arom.), 128.6 (s, CH-arom.), 132.7 (s, C-arom., anti-2j), 134.5
(s, C-arom., syn-2j), 170.8 (s, C(O)CH3, anti-2j), 170.9 (s, C(O)CH3, syn-2j). MS (EI, 70 eV)
m/z 207 (3), 164 (13), 147 (100), 133 (45), 127 (21), 117 (15), 115 (29), 107 (5), 101 (5), 89
(5), 77 (8), 63 (13), 51 (8). Anal.: calcd. for C12H12BrFO2: C, 50.20%; H, 4.21%. Found: C,
49.97%; H, 4.01%.
4.3.11.
(2-Bromo-2-fluorocyclopropyl)methyl benzoate (2k)
Obtained by the general procedure (the reaction time — 48 hours) after column
chromatography (n-hexane/EtOAc, 10/1) as a colorless oil (168.4 mg, 92% purity, 57% yield,
syn-/anti- = 49/51). This product could not be separated from 5 mol.% (8 w/w %) of side 2,4,4-
tribromo-4-fluorobutyl benzoate 3.
1H NMR (300.1 MHz, CDCl3) : 1.18–1.30 (m, 1H, syn-2k), 1.42–1.64 (m, 2H, anti-2k),
1.72–1.87 (m, 1H, syn-2k), 1.94–2.16 (m, 2H, both isomers), 4.24 (dd, 1H, syn-2k, J = 11.9,
8.1 Hz), 4.35 (ddd, 1H, anti-2k, J = 11.9, 8.2, 1.7 Hz, 1H), 4.48 (ddd, 1H, syn-2k, J = 11.9,
6.5, 2.1 Hz, 1H), 4.54 (ddd, 1H, anti-2k, J = 12.1, 6.9, 1.8 Hz, 1H), 7.40–7.51 (m, 2H, arom.
both isomers), 7.53–7.62 (m, 1H, arom. both isomers), 8.03–8.12 (m, 2H, arom. both
isomers). 19F NMR (282.4 MHz, CDCl3) : –129.7 (dddd, syn-2k, J = 18.5, 16.4, 7.6, 2.4 Hz),
13
–149.5 (dddt, J = 17.3, 8.7, 1.8, 1.8 Hz). C NMR (75.5 MHz, CDCl3) : 21.2 (d, CH2, J =
10.9 Hz), 21.2 (d, CH2, J = 10.8 Hz), 24.0 (d, CH, J = 11.1 Hz), 27.0 (d, CH, J = 10.3 Hz),
61.8 (d, CH2OBz, J = 7.4 Hz), 65.3 (d, CH2OBz, J = 1.0 Hz), 79.8 (d, CFBr, J = 273 Hz),
83.7 (d, CFBr, J = 270 Hz), 128.4 (s, CH-arom.), 128.4 (s, CH-arom.), 129.7 (s, CH-arom.),
129.7 (s, CH-arom.), 129.8 (s, C-arom.), 129.9 (s, C-arom.), 133.2 (s, CH-arom.), 133.2 (s,
CH-arom.), 166.3 (s, C=O), 166.4 (s, C=O). MS (EI, 70 eV) m/z 272/274 ([M+], 1/1), 193 (1),
148 (7), 106 (10), 105 (100), 77 (36), 51 (39). Anal.: calcd. for the mixture of 95 mol.% of
C11H10BrFO2 and 5 mol.% of C11H10Br3FO2: C, 47.00%; H, 3.59%. Found: C, 46.82%; H,
3.69%.

13
4.3.12.
2,4,4-tribromo-4-fluorobutyl benzoate (3)
Chemical shifts were assigned from {1H,13C}-HSQC,HMBC and {1H,19F}-HMBC spectra
for 2k,3 mixture (a ratio 2k/3 = 95/5).
1H NMR (300.1 MHz, CDCl3) : 3.39–3.61 (m, 2H, CFBr2CH2), 4.54–4.65 (m, 1H,
CHBr), 4.59–4.69 (m, 2H, CH2OBz), (signals for OBz are overlapped with 2k). 19F NMR (282.4
MHz, CDCl3) : –47.4 (dd, J = 18.2, 17.0 Hz). 13C NMR (75.5 MHz, CDCl3) : 43.4 (s, CHBr),
57.3 (d, CFBr2CH2, J = 19.3 Hz), 66.9 (d, CH2OBz, J = 1.8 Hz), 92.1 (d, CFBr2, J = 321 Hz),
128.6 (s, CH-arom.), 129.8 (s, CH-arom.), 133.5 (s, CH-arom.), 165.7 (s, C=O), (quaternary
carbon from OBz-group was missed due to low intensity). MS (EI, 70 eV) m/z 351/353/355
([M–Br]+, 1/2/1), 229/231/232 (7/14/6), 123 (33), 122 (64), 105 (100), 77 (46), 51 (53).
4.3.13.
(2-Bromo-1,2-difluoro-3,3-dimethylcyclopropyl)methyl acetate (2l)
Obtained by the general procedure (the reaction time — 18 hours) after column
chromatography (n-hexane/EtOAc, 10/1) as a colorless oil (229.0 mg, 89% yield, syn-/anti- =
41/59). During rotary evaporation and further drying 10 mmHg and 30°C were used.
1H NMR (300.1 MHz, CDCl3) : 1.26 (t, 3H, CH3, J = 1.5 Hz), 1.28 (t, 3H, CH3, J = 1.9 Hz),
1.29 (t, 3H, CH3, J = 1.8 Hz), 1.32 (t, 3H, CH3, J = 2.4 Hz), 2.13 (s, 3H, C(O)CH3, 1H), 2.14
(s, 3H, C(O)CH3, 3H), 4.36–4.61 (m, 2H, CH2, both isomers). 19F NMR (282.4 MHz, CDCl3)
: –148.36 (s, 1F, CFBr, syn-2l), –153.82 (s, 1F, CFBr, anti-2l), –186.10 (t, 1F, CF, syn-2l, J
= 24.1 Hz), –202.52 (t, 1F, CF, anti-2l, J = 24.3 Hz). 13C NMR (75.5 MHz, CDCl3) : 12.7 (t,
CH3, J = 11.2 Hz), 15.0 (d, CH3, J = 10.1 Hz), 19.0 (dd, CH3, J = 8.7, 2.3 Hz), 20.7 (s,
C(O)CH3), 20.7 (s, C(O)CH3), 21.1 (d, CH3, J = 1.4 Hz), 31.6 (dd, C(Me)2, J = 12.1, 8.4 Hz),
33.0 (dd, C(Me)2, J = 13.0, 10.8 Hz), 60.4 (dd, CH2OAc, J = 22.0, 5.2 Hz), 63.4 (dd,
CH2OAc, J = 21.5, 1.4 Hz), 80.1 (dd, CF, J = 242, 10.4 Hz), 80.2 (dd, CF, J = 243, 9.7 Hz),
87.6 (dd, CFBr, J = 312, 10.7 Hz), 90.2 (dd, CFBr, J = 310, 13.5 Hz), 170.5 (s, C(O)), 170.5
(s, C(O)). MS (EI, 70 eV) m/z 196/198 (2/2), 177 (3), 117 (100), 103 (22), 97 (58), 83 (15), 77
(57), 73 (21), 67 (28), 59 (21), 51 (26). Anal.: calcd. for C8H11BrF2O2: C, 37.38%; H, 4.31%.
Found: C, 37.31%; H, 4.52%.
4.3.14.
Benzyl 2-bromo-2-fluorocyclopropane-1-carboxylate (2m)
Obtained by the general procedure on 1.0 mmol scale using total 8.0 equiv. of
CFBr2CO2Na. First, 4.0 equiv. of CFBr2CO2Na were added and the reaction mixture was heated

14
for 24 hours. Additional 4.0 equiv. of CFBr2CO2Na were added and the reaction mixture was
heated for 48 hours more. The final GC ratio of starting alkene 1m and cyclopropane 2m was
25/75. For purification from residual 1m, the crude product was chromatographed twice on 15 g
of silica eluting with n-hexane/EtOAc (15/1) affording 2m as a colorless oil (141.6 mg, 52%
yield, syn-/anti- = 44/56).
1H NMR (300.1 MHz, CDCl3) : 1.73 (dt, 1H, CH2, anti-2m, J = 10.0, 8.0 Hz), 1.86–1.99 (m,
2H, CH2, syn-2m), 2.28 (dt, 1H, CH2, anti-2m, J = 17.3, 7.8 Hz), 2.42–2.59 (m, 2H,
CH(CO2Bn), both isomers), 5.12–5.25 (m, 2H, Bn, both isomers), 7.29–7.42 (m, 5H, arom.).
19F NMR (282.4 MHz, CDCl3) : –127.0 (ddd, syn-2m, J = 17.3, 15.6, 11.3 Hz), –145.5 (ddd,
13
anti-2m, J = 17.2, 8.2, 1.6 Hz). C NMR (75.5 MHz, CDCl3) : 22.6 (d, CH2, syn-2m, J =
9.4 Hz), 23.2 (d, CH2, anti-2m, J = 10.9 Hz), 28.7 (d, CH, syn-2m, J = 12.1 Hz), 30.8 (d, CH,
anti-2m, J = 10.8 Hz), 67.5 (s, CH2Ph, anti-2m), 67.6 (s, CH2Ph, syn-2m), 77.6 (d, CFBr,
anti-2m, J = 308 Hz), 79.6 (d, CFBr, syn-2m, J = 299 Hz), 128.4 (s, CH-arom.), 128.5 (s,
CH-arom.), 128.6 (s, CH-arom.), 128.6 (s, CH-arom.), 128.7 (s, CH-arom.), 128.7 (s, CH-
arom.), 135.3 (s, C-arom., both isomers), 166.1 (d, C=O, anti-2m, J = 1.5 Hz), 167.3 (d, C=O,
syn-2m, J = 1.1 Hz). MS (EI, 70 eV) m/z 272/274 ([M+], 3/3), 200/202 (13/13), 165 (9), 148
(32), 147 (23), 137 (9), 92 (9), 91 (100), 77 (4), 69 (11). Anal.: calcd. for C11H10BrFO2: C,
48.38%; H, 3.69%. Found: C, 48.43%; H, 3.55%.
4.3.15.
Methyl 2-bromo-2-fluoro-3-phenylcyclopropane-1-carboxylate (2n)
Obtained by the general procedure on 1.0 mmol scale using total 8.0 equiv. of
CFBr2CO2Na. First, 4.0 equiv. of CFBr2CO2Na were added and the reaction mixture was heated
for 24 hours. The 50% conversion was reached. Additional 4.0 equiv. of CFBr2CO2Na were
added and the reaction mixture was heated for 48 hours more. The final GC ratio of starting
alkene 1n and cyclopropane 2n was 8/92. Isolation by column chromatography on 15 g of silica
eluting with n-hexane/EtOAc (15/1) gave 2n as a colorless oil (192.0 mg, 70% yield, syn-/anti- =
69/31).
1H NMR (300.1 MHz, CDCl3) : 2.72–2.88 (m, 1H, CH(Ph)), 3.32 (dd, 1H, CH(CO2Me),
anti-2n, J = 8.5, 5.7 Hz), 3.53 (dd, 1H, CH(CO2Me), syn-2n, J = 19.4, 8.4 Hz, 1H), 3.82 (s,
19
3H, CO2CH3, syn-2n), 3.82 (s, 3H, CO2CH3, anti-2n), 7.13–7.43 (m, 5H, arom.). F NMR
(282.4 MHz, CDCl3) : –135.0 (dd, syn-2n, J = 19.4, 1.9 Hz), –137.2 (dd, anti-2n, J = 18.3,
13
5.7 Hz). C NMR (75.5 MHz, CDCl3) : 34.2 (d, CH, anti-2n, J = 11.7 Hz), 35.6 (d, CH,
syn-2n, J = 10.8 Hz), 36.7 (d, CH, syn-2n, J = 10.7 Hz), 38.9 (d, CH, anti-2n, J = 8.8 Hz),

15
52.8 (s, OMe, syn-2n), 52.9 (s, OMe, anti-2n), 80.7 (d, CFBr, anti-2n, J = 304 Hz), 84.1 (d,
CFBr, syn-2n, J = 312 Hz), 128.1 (s, CH-arom., anti-2n), 128.1 (s, CH-arom., syn-2n), 128.4
(d, CH-arom., anti-2n, J = 1.3 Hz), 128.4 (d, CH-arom., syn-2n, J = 1.9 Hz), 128.6 (s, CH-
arom., syn-2n), 128.7 (s, CH-arom., anti-2n), 131.3 (d, C-arom., anti-2n, J = 1.7 Hz), 133.2
(s, C-arom., syn-2n), 166.5 (d, –CO2Me, syn-2n, J = 1.8 Hz), 167.6 (d, –CO2Me, anti-2n, J =
2.1 Hz). MS (EI, 70 eV) m/z 272/274 ([M+], 1/1), 213/215 (3/3), 193 (35), 165 (25), 162 (10),
145 (9), 133 (100), 115 (6), 107 (6), 77 (7), 59 (14). Anal.: calcd. for C11H10BrFO2: C,
48.38%; H, 3.69%. Found: C, 48.19%; H, 3.82%.
4.3.16.
2-Bromo-2-fluoro-1-hexylcyclopropane (2s)
Obtained by the general procedure on 20 mmol scale. After the reaction complete, it was
diluted with pentane and filtered through a short plug of silica. The filtrate was concentrated on a
rotary evaporator (200 mmHg, 30°C), and ‘bulb-to-bulb’ distilled (10 mmHg, bath temp. 110–
120°) affording 2s as a colorless liquid (3.79 g, 85% yield, syn-/anti- = 46/54). NMR data are
fully consistent with previously published [10b].
1H NMR (300.1 MHz, CDCl3) : 0.83–0.95 (m, 3H, CH3), 1.01–1.67 (m, 13H). 19F NMR
13
(282.4 MHz, CDCl3) : –126.7 (m, syn-2s), –149.0 (dd, anti-2s, J = 17.7, 7.3 Hz). C NMR
(75.5 MHz, CDCl3) : 14.1 (s, CH3), 22.4 (d, CH2-cycloprop., J = 10.1 Hz), 22.7 (s, CH2),
22.7 (d, CH2-cycloprop., J = 10.8 Hz), 25.8 (d, CH-cycloprop., J = 9.0 Hz), 27.3 (d, CH2, J =
4.8 Hz), 28.4 (s, CH2), 29.0 (s, CH2), 28.9 (s, CH2), 29.0 (s, CH2), 29.3 (d, CH-cycloprop., J =
10.8 Hz), 31.8 (s, CH2), 31.8 (s, CH2), 82.7 (d, CFBr, J = 302 Hz), 88.0 (d, CFBr, J = 298
Hz).
Acknowledgements
This work was funded by RFBR according to the research project № 16-33-00620 mol_а and the
Russian Federation President Council for Grants (Program for State Support of Leading
Scientific Schools of the Russian Federation, grant no. NSh-8012.2016.3). Authors greatly thank
Dr. Roman A. Novikov from ZIOC RAS for 1D and 2D NMR assistance.
Supplementary Data
Copies of 1H, 19F, and 13C NMR spectra.

16
References
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Chem. 193 (1997) 131–195;
(b) P. Kirsch, Modern Fluoroorganic Chemistry: Synthesis, Reactivity, Applications, Wiley-
VCH Verlag GmbH & Co. KGaA, 2004;
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(52%).
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137.

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22
Figure 1. Unsuccessful examples
a 2k contained 5 mol.% of 2,4,4-tribromo-4-fluorobutyl benzoate 3;
;
b 8.0 equiv. of CFBr2CO2Na were used;
Scheme 1. Substrate scope of cyclopropanation with CFBr2CO2Na/(IPr)AgCl
Scheme 2. Multi-gram scale synthesis of 2s

23
Table 1. Catalyst screening a,b
Entry Solvent
Catalyst
(10 mol.%)
T°C
time
Yield of 2a
(%, 19F NMR) (GC ratio)
Recovery
CFBr2CO2Na
(%,19F NMR)
—
of Yield of CFBr3
(% to CFBr2CO2Na,
19F NMR)
1a/2a
1
diglyme
diglyme
diglyme
diglyme
diglyme
diglyme
DCE
—
100°C
100°C
100°C
100°C
100°C
100°C
70°C
20 min
20 min
20 min
20 min
20 min
20 min
40 min
40 min
40 min
40 min
40 min
5 h
29%
9%
78/22
94/6
24%
2
Ph3P
—
27%
30%
23%
27%
29%
0%
3
18-crown-6
TEBAC
(SIPr)CuCl
(IPr)AgCl
—
18%
25%
18%
30%
0%
73/27
76/24
88/12
81/19
100/0
65/35
86/14
100/0
80/20
0/100
0/100
—
4
—
5
—
6
—
7
100%
7%
8
DCE
TEBAC
18-crown-6
(IPr)AuCl
(IPr)AgCl
(IPr)AgCl
(SIPr)AgCl
70°C
35%
13%
0%
17%
30%
0%
9
DCE
70°C
11%
100%
92%
13%
29%
10
11
12
13
DCE
70°C
DCE
70°C
12%
78%
65%
2%
DCE
70°C
70°C
10%
1%
DCE
5 h
a Experimental procedure (in diglyme): To a solution of 1a (0.10 mmol) and an Additive (10 mol.%) in 0.50 mL of diglyme at 100°C, CFBr2CO2Na (0.40
19
mmol) was slowly added over 10 min. The reaction mixture was stirred for additional 10 min at 100°C until CO2 no longer evolved. F NMR yields were
determined using 4-fluoroanisole (5.0 L) as an internal standard.
b
Experimental procedure (in DCE): A mixture of 0.10 mmol of 1a, 0.40 mmol of CFBr2CO2Na and an Additive (10 mol.%) was dried under high
vacuum for 1 hour, DCE (0.50 mL) was added and the reaction mixture was heated for specified time. 4-Fluoroanisole (5.0 L) and water solution of
CF3CO2Na (5–10 mg) were added. 19F NMR yields were determined.

24
Abbreviatures: pin = pinacolyl-, DCE = 1,2-dichloroethane; TEBAC = benzyl(triethyl)ammonium chloride;