One-pot addition-intramolecular N-cyclization of carbamates mediated by alkali metallic reagents as an approach to 4-(fluoroalkyl)oxazolidin-2-ones

Article abstract of DOI:10.1055/s-0030-1260239

A mild and straightforward strategy for the synthesis of 4-(fluoroalkyl)oxazolidin-2-ones via one-pot addition-intramolecular N-cyclization of allyl carbamates with fluoroalkyl iodides is presented. The reaction proceeded in moderate to good yield through regiocontrol and an increase in the reactivity of the ambident nucleophiles by the use of alkali metallic reagents. Georg Thieme Verlag Stuttgart. New York.

Full text of DOI:10.1055/s-0030-1260239

PAPER
3627
One-Pot Addition–Intramolecular N-Cyclization of Carbamates Mediated by
Alkali Metallic Reagents as an Approach to 4-(Fluoroalkyl)oxazolidin-2-ones
O
ne-Pot Synthesis
u
of 4-(Fluoro
e
alkyl)oxaz
o
-
lidin-2-
Y
ones from
A
llyl
C
a
a
rbamates n Yang,a Xiang Fang,*a Zheng-Hua Ju,a Yun-Li Hu,a Fan-Hong Wu*a,b
a
Laboratory for Advanced Material and Institute of Fine Chemicals, School of Chemistry and Molecular Engineering,
East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, P. R. of China
Fax +86(21)64253074; E-mail: fangxiang@ecust.edu.cn; E-mail: wfh@ecust.edu.cn
b
School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 200235, P. R. of China
Received 23 July 2011; revised 20 August 2011
It is well known that the introduction of fluorine atom(s)
into organic molecules sometimes enhances or greatly
changes biological activities.8 3-(Trifluoromethyl)oxazo-
lidin-2-one is useful as a synthetic building block for the
Abstract: A mild and straightforward strategy for the synthesis of
4-(fluoroalkyl)oxazolidin-2-ones via one-pot addition–intramolec-
ular N-cyclization of allyl carbamates with fluoroalkyl iodides is
presented. The reaction proceeded in moderate to good yield
through regiocontrol and an increase in the reactivity of the ambi- preparation of organophosphorus compounds, which have
dent nucleophiles by the use of alkali metallic reagents.
been recognized as one of the most potentially important
and efficient components of insecticidal, miticidal and
nematicidal agents.9 4-(Fluoroalkyl)oxazolidin-2-ones
might also be useful as synthetic building blocks for the
preparation of potential drugs or as precursors of fluorine-
containing amino acids.10 Herein, we present our results in
this area and disclose a straightforward, one-pot protocol
for 4-(fluoroalkyl)oxazolidin-2-ones based on a radical-
adduct-mediated cyclization reaction under alkali condi-
tions.
Key words: allyl carbamates, 4-(fluoroalkyl)oxazolidin-2-ones,
addition–intramolecular N-cyclization, alkali metallic reagents
Halocyclizations of unsaturated compounds with an in-
tramolecular nucleophilic center are well established as an
indispensable tool in the synthesis of heterocyclic com-
pounds.1 In the halocyclization reactions of carbamates or
amides, O-cyclized products are generally obtained in
preference to N-cyclized products.2 To achieve N-cy-
clized products, Taguchi and co-workers have reported
the efficient iodine-mediated cyclization with n-butyllith-
ium or LiAl(Ot-Bu)4 as the alkali metallic reagent.3 More
recently, in a continuing program on the chemistry of
fluoroalkyl iodides, we have demonstrated the addition–
lactonization of pent-4-enoic acids with fluoroalkyl
iodides, which easily afforded fluoroalkyl-substituted lac-
tones.4 Furthermore, the addition–lactamization of pent-
4-enamides with fluoroalkyl iodides resulted in fluoro-
alkyl-substituted lactones rather than lactams.5 On the ba-
sis of these results, we envisioned that the reaction of
carbamates with fluoroalkyl iodides would result in a se-
ries of novel 4-(fluoroalkyl)oxazolidin-2-ones via a
tandem radical addition–intramolecular nucleophilic sub-
stitution process mediated by an alkali metallic reagent.
Synthetic investigations of the target oxazolidin-2-ones
were initiated with the preparation of allyl ethoxycarbon-
ylcarbamate (1a), allyl acetylcarbamate (1b) and allyl
benzoylcarbamate (1d) (Figure 1). These allyl carbamates
were conveniently prepared from the corresponding iso-
cyanates in accordance with Scheme 1.3 Allyl phenylcar-
bamate (1e) and ethyl (allylthio)carbonylcarbamate (1g)
were prepared similarly, while allyl tert-butoxycarbonyl-
carbamate (1c) was prepared through a three-step proce-
dure developed by Chong and Park.11
With the allyl carbamates 1a–g in hand, we next turned to
the study of their reactivity in the free-radical addition,
using 1,1,2,2,3,3,4,4,5,5,6,6,6-tridecafluorohexyl iodide
O
O
O
O
O
NH2
Meanwhile, oxazolidin-2-one derivatives have attracted a
great deal of interest owing to their wide application in
various fields, such as materials science and medicinal
chemistry.6 Over the past decade, a new class of synthetic
antibacterial agents have been referred to as oxazolidi-
none antibiotics.7 They have potent activity against a va-
riety of Gram-positive bacterial pathogens including
methicillin-resistant Staphylococcus aureus (MRSA) and
vancomycin-resistant Enterococci (VRE). For these rea-
sons, new methods of accessing these classes of com-
pounds continue to be reported.
O
N
R
O
NHPh
H
1e
1f
1a R = OEt
1b R = Me
1c R = Ot-Bu
1d R = Ph
O
O
O
O
N
H
O
S
N
H
O
1g
1h
Figure 1
O
O
O
O
(COCl)2
OH
R
N C O
R
NH2
O
N
R
H
1a R = OEt
1b R = Me
1d R = Ph
SYNTHESIS 2011, No. 22, pp 3627–3634
Advanced online publication: 26.09.2011
x
x.
x
x
.
2
0
1
1
DOI: 10.1055/s-0030-1260239; Art ID: F72511SS
© Georg Thieme Verlag Stuttgart · New York
Scheme 1

3628
X.-Y. Yang et al.
PAPER
[CF3(CF2)5I, 2b] as a model substrate (Table 1). It has reaction could proceed smoothly and the adducts were ob-
been reported that the addition of fluoroalkyl iodides to tained in low yields (Table 1, entries 11–13). Notably, the
unsaturated compounds could be conveniently initiated addition reaction between ethyl (allylthio)carbonylcar-
by sodium dithionite,4 AIBN,12 and metals and metal bamate (1g) and 2b failed in all conditions, such as AIBN/
complexes [e.g., Cu, Mg, Zn/NiCl6, Cp2TiCl2/Fe, Na2S2O4/Pd(PPh3)4 (Table 1, entry 14). Compound 1g
Pd(PPh3)4].13 Interestingly, no reaction took place when might undergo a radical cleavage to provide sulfur radical
allyl carbamate 1a was exposed to 2b under the usual con- which might result in a decomposition product.
ditions (Table 1, entries 1 and 3) or gave reductive prod-
Next, we further optimized the intramolecular N-cycliza-
uct in poor yield (Table 1, entry 2). It was found that the
tion conditions with alkali metallic reagents. After a sur-
structure of substrate 1 is critical for the addition efficien-
vey of alkali reagents for the improvement of
nucleophilicity, it was pleasing to see that the intramolec-
ular cyclization reaction with sodium hydride proceeded
to give the N-cyclized products 4 in good yields (Table 1,
cy. The reaction of allyl carbamates 1a–c with 2b initiated
by AIBN afforded the corresponding adducts 3 in 66%,
82% and 61% yield, respectively (Table 1, entries 5, 8 and
9); however, the substrates 1d–f did not react completely
entries 6, 8, 9 and 11). Meanwhile, it was worthwhile to
when AIBN was used as initiator (Table 1, entry 10). In
note that the protecting group of the N atom showed a
contrast, when sodium dithionite was used as initiator, the
Table 1 Optimization of the Reaction Conditions for the Addition–Intramolecular N-Cyclization Reaction of Allyl Carbamates 1 with Fluo-
roalkyl Iodides 2
O
O
M
N
O
O
O
O
X
O
N-cyclization
initiator
alkali metallic reagent
NHR
NH
+
RFI
RF
X
NHR
RF
X
R
X
NHR
or
I
I
X = O, S
RF
RF
2b RF = (CF2)5CF3
2e RF = CF2SPh
4
5
1
3
Entry
1
Substrate 1 Substrate 2 Initiator
Temp (°C), time (h) Yielda (%) of 3 Alkali
Yielda (%) of 4 (or 5)
1a
1a
1a
1a
1a
1a
1a
1b
1c
2b
2b
2b
2b
2b
2b
2b
2b
2b
2b
2b
2b
2b
2b
2e
2e
2e
2e
Cu
100, 7
60, 12
100, 7
25, 3
trace
5b
2
Zn/NiCl6
Pd(PPh3)4
Na2S2O4
AIBN
3
trace
32
4
c
5
80, 2
66
NaOH
NaH
6
AIBN
80, 2
66
70
30
76
67
7
AIBN
80, 2
66
n-BuLi
NaH
8
AIBN
80, 2
82
9
AIBN
80, 2
61
NaH
d
10
11
12
13
14
15
16
17
18
1d–f
1d
1e
AIBN
80, 3
Na2S2O4
Na2S2O4
Na2S2O4
25, 3
34
52
37
0
NaH
LiOH
NaH
65
25, 3
29
1f
25, 3
trace
1g
1a
1a
1a
1a
AIBN/Na2S2O4/Pd(PPh3)4
Na2S2O4
80, 2/25, 3/100, 7
25, 2
70
70
70
70
NaOH
n-BuLi
NaH
5ae: 75
5ae: 25
5ae: 55
0
Na2S2O4
25, 2
Na2S2O4
25, 2
Na2S2O4
25, 2
Na2CO3
a Isolated yields.
b Reductive product.
c The reaction gave a complex mixture.
d The substrate did not react completely.
Synthesis 2011, No. 22, 3627–3634 © Thieme Stuttgart · New York

PAPER
One-Pot Synthesis of 4-(Fluoroalkyl)oxazolidin-2-ones from Allyl Carbamates
3629
Table 3 One-Pot Synthesis of 4-(Fluoroalkyl)oxazolidin-2-ones 4a
great effect on the yield of cyclization; the yields in the
case of carbonyl groups were better than those substrates
without a protecting group or with a phenyl group as the
protecting group (Table 1, entries 12 and 13). With one
more electron-withdrawing carbonyl group on 1a–d, the
pKa values of the corresponding amides are lower than
those for 1e and 1f. It has also been observed that sodium
hydride may bring about an increase in the reactivity to-
gether with regiocontrol of an ambident nucleophile Entry
O
O
O
O
O
AIBN, NaH
N
+
RFI
R
O
N
R
H
RF
1a R = OEt
1b R = Me
1c R = Ot-Bu
2b RF = (CF2)5CF3
2c RF = (CF2)7CF3
2d RF = CF2P(O)(OEt)2
4
Substrate 1
Substrate 2
Yieldb (%) of 4
4ab: 82
through the formation of a metal imino alkolate interme-
1
1a
1a
1a
1b
1b
1b
1c
1c
2b
2c
2d
2b
2c
2d
2b
2d
diate.3
2
4ac: 66
In particular, we further optimized the addition–intramo-
lecular N-cyclization conditions for 1a with 2e taking into
3
4ad: 69
account the special characteristics of difluoro(phenyl-
thio)methyl iodide (2e).11 By screening for the influence
4
4bb: 62
4bc: 78
of the radical initiator and alkali reagents on the product
yield, we found that the addition initiated by sodium
5
6
7
8
4bd: 65
4cb: 58
dithionite and the cyclization mediated by sodium hy-
droxide with subsequent loss of the protecting group
(ethoxycarbonyl) led to the optimal yield (Table 1, entry
15).
4cd: 50
a Conditions: carbamate 1 (0.5 mmol), RFI (1 mmol), AIBN (10 mg),
80 °C, 2 h; then, NaH (1 equiv), THF (5 mL), r.t., 2 h.
b Isolated yields.
Under the optimized reaction conditions (Table 1, entry
11), we investigated the additions of carbamate 1d with
iodides 2 initiated by sodium dithionite, and subsequent
treatment with sodium hydride to afford the N-cyclized
products, the 4-(fluoroalkyl)oxazolidin-2-ones 4, in low
yields in two steps (Table 2, entries 3 and 4). Neverthe-
less, the additions of carbamates 1 with 2-chloro-1,1,2,2-
tetrafluoroethyl iodide (ClCF2CF2I, 2a) were initiated
with sodium dithionite due to the low boiling point of 2a.
ethoxycarbonylcarbamate (1a) reacted with 2b to achieve
the target product 4ab in one pot, and the yield was im-
proved from 46% (Table 1, entry 6) to 82% (Table 3, en-
try 1).
The results of the one-pot reaction of allyl carbamates 1a–
d with difluoro(phenylthio)methyl iodides 2e,f are shown
in Table 4. It should be mentioned that the N-unsubstitut-
ed cyclic carbamates 5ae and 5af were obtained through
the addition–intramolecular N-cyclization and subsequent
loss of the protecting group in the presence of sodium
dithionite and sodium hydroxide. The decarbonylation
was generally observed in the AIBN/sodium hydride sys-
tem; the reaction of N-protected derivative 1b with 2e,f
To increase the reaction efficiency, the addition–intramo-
lecular N-cyclization was undertaken in one pot without
purification of the addition mixture by flash column chro-
matography. With the optimized reaction conditions
(Table 1, entry 6), we explored the scope of the one-pot
addition–cyclization reaction between allyl carbamates
1a–c and iodides 2b–d. As illustrated in Table 3, all the
carbamates 1 afforded the 4-(fluoroalkyl)oxazolidin-2-
ones 4 in moderate to excellent yields. For example, allyl
Table 2 Synthesis of 4-(Fluoroalkyl)oxazolidin-2-ones in Two Steps
O
O
O
N
R
O
O
O
O
Na2S2O4
n-BuLi or NaH
+
RFI
O
N
R
RF
O
N
R
H
H
I
RF
1a R = OEt
1b R = Me
1d R = Ph
2a RF = CF2CF2Cl
2b RF = (CF2)5CF3
2d RF = CF2P(O)(OEt)2
3
4
Entry
Substrate 1
Substrate 2
Yielda,b (%) of 3
Base
Yieldb (%) of 4
4aa: 29
1
2
3
4
1a
1b
1d
1d
2a
2a
2b
2d
3aa: 55
3ba: 25
3db: 34
3dd: 37
n-BuLi
n-BuLi
NaH
4ba: 45
4db: 65
NaH
4dd: 67
a Conditions: carbamate 1 (0.5 mmol), RFI (0.55 mmol), Na2S2O4 (0.69 mmol), NaHCO3 (0.75 mmol), MeCN–H2O (3:1, 2 mL), 25 °C, 3 h.
b Isolated yields.
Synthesis 2011, No. 22, 3627–3634 © Thieme Stuttgart · New York

3630
X.-Y. Yang et al.
PAPER
tramolecular cyclization of 3hb with sodium carbonate in
dimethyl sulfoxide gave O-cyclized product 6. The one-
pot reaction of 1h with iodide 2b on treatment with
Pd(PPh3)4/sodium carbonate afforded O-cyclized product
6 in 74% yield, while the use of Pd(PPh3)4/n-butyllithium
gave elimination product 7 in 48% yield (Scheme 2).
Table 4 One-Pot Synthesis of 4-(Fluoroalkyl)oxazolidin-2-ones 5
O
O
O
Na2S2O4, NaOH
or AIBN, NaH
O
NH
+
RFI
O
N
R
H
1a R = OEt
1b R = Me
1c R = Ot-Bu
1d R = Ph
2e RF = CF2SPh
2f RF = CF2SC6H4-4-Cl
RF
5
In conclusion, we have successfully developed a mild and
efficient method for the free-radical addition–intramolec-
ular N-cyclization reaction of allyl carbamates with fluo-
roalkyl iodides mediated by strong alkali reagents. This
one-pot synthesis of 4-(fluoroalkyl)oxazolidin-2-ones
may provide new insights toward the further development
of novel (fluoroalkyl)oxazolidin-2-one derivatives that
have wide applications in medicinal chemistry. Further bi-
ological studies of the 4-(fluoroalkyl)oxazolidin-2-ones
obtained in this paper are currently under way in our lab-
oratory.
Entry
Substrate 1
Substrate 2
Yielda (%) of 5
5ae: 56b
5af: 51b
1
2
3
4
5
6
7
8
1a
1a
1b
1b
1c
1c
1d
1d
2e
2f
2e
2f
2e
2f
2e
2f
5ae: 58c
5af: 54c
5ae: 53b
5af: 50b
5ae: 36b
5af: 33b
Melting points were determined on a WSR-IB digital melting point
apparatus and are uncorrected. 1H (500 MHz) and 13C (125.8 MHz)
NMR spectra were recorded on a Bruker AC-500 spectrometer with
TMS as internal standard. 19F NMR spectra (470 MHz) were ob-
tained in CDCl3 on a Bruker AC-500 spectrometer with CFCl3 as
external standard, downfield shifts being designated as negative. IR
spectra were measured on a Nicolet Magna-IR 550 spectrometer.
High-resolution mass spectra were carried out on a Finnigan GC-
MS-4021 spectrometer. All reagents were used as received from
commercial sources. Column chromatography was performed over
silica gel (300–400 mesh) using petroleum ether–ethyl acetate as
the eluent.
a Isolated yields.
b Conditions: carbamate 1 (0.5 mmol), RFI (0.55 mmol), Na2S2O4
(0.69 mmol), NaOH (0.75 mmol), MeCN–H2O (3:1, 2 mL), 25 °C, 1
h.
c Conditions: carbamate 1 (0.5 mmol), RFI (1 mmol), AIBN (10 mg),
80 °C, 2 h; then, NaH (1 equiv), THF (5 mL), r.t., 2 h.
also proceeded in moderate yield to give the N-cyclized
products 5ae and 5af (Table 4, entries 3 and 4).
Allyl Ethyl Imidodicarbonate (1a);3 Typical Procedure
Oxalyl chloride (36 mL, 0.42 mol) was added via dropping funnel
to ethyl carbamate (26.7 g, 0.3 mol) in anhyd DCE (150 mL) at
0 °C. The solution was allowed to warm to r.t. and then refluxed
with stirring for 24 h. Then, the resulting mixture was cooled to r.t.
and allyl alcohol (0.9 mL, 0.28 mol) was added. After the reaction
was completed, the resulting mixture was concentrated under re-
duced pressure to leave a residue, which was further purified by
vacuum distillation, providing 1a as a colorless oil; yield: 17 g
(35%).
We have reported the reaction of pent-4-enamides with
fluoroalkyl iodides catalyzed by Pd(PPh3)4 to give fluo-
rine-containing lactones after treatment with triethyl-
amine.5 If tert-butyl 3,3-dimethylpent-4-enoylcarbamate
(1h), prepared from the corresponding pent-4-enamide,
was used as substrate, we envisioned that the N-Boc sub-
stitution mediated by alkali reagents would potentially
lead to N-cyclized lactam. Unfortunately, the adduct 3hb,
which was obtained from the substrate 1h with iodide 2b
initiated by catalytic Pd(PPh3)4, only afforded elimination
product 7 under the influence of n-butyllithium. The in-
1H NMR (500 MHz, CDCl3): d = 7.28 (br, 1 H), 5.97–5.89 (m, 1 H),
5.37 (dd, J = 17.2, 1.4 Hz, 1 H), 5.28 (dd, J = 10.4, 1.2 Hz, 1 H),
OH
O
O
O
O
(COCl)2
N
C O
NH2
N
H
O
1h
O
NHBoc
CF3(CF2)5I 2b
CF3(CF2)5I 2b
1h
Pd(PPh3)4, Na2CO3
Pd(PPh3)4, n-BuLi
Pd(PPh3)4
O
CF3(CF2)5I 2b
48%
74%
O
O
O
n-BuLi
THF
Na2CO3
DMSO
C6F13
NHBoc
C6F13
NHBoc
I
C6F13
6
7
3hb
Scheme 2
Synthesis 2011, No. 22, 3627–3634 © Thieme Stuttgart · New York

PAPER
One-Pot Synthesis of 4-(Fluoroalkyl)oxazolidin-2-ones from Allyl Carbamates
3631
4.67 (dt, J = 5.8, 1.2 Hz, 2 H), 4.25 (q, J = 7.1 Hz, 2 H), 1.30 (t,
J = 7.1 Hz, 3 H).
MS (EI): m/z (%) = 227 (1) [M+], 171 (25), 110 (55), 57 (100).
HRMS (EI): m/z calcd for C12H21NO3: 227.1521; found: 227.1522.
Allyl Acetylcarbamate (1b)
White solid; mp 61.5–62.5 °C.
IR (KBr): 3222, 1762, 1703, 1220, 772 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.44 (br, 1 H), 5.97–5.88 (m, 1 H),
5.36 (dd, J = 17.2, 1.4 Hz, 1 H), 5.30 (dd, J = 10.4, 1.1 Hz, 1 H),
4.65 (dt, J = 5.8, 1.2 Hz, 2 H), 2.44 (s, 3 H).
13C NMR (125.8 MHz, CDCl3): d = 173.6, 152.6, 131.9, 119.6,
67.2, 24.6.
Ethyl 4-(3-Chloro-2,2,3,3-tetrafluoropropyl)-2-oxooxazolidine-
3-carboxylate (4aa); Typical Two-Step Procedure
To a mixture of carbamate 1a (87 mg, 0.5 mmol) and ClCF2CF2I
(2a; 140 mg, 0.55 mmol) in MeCN–H2O (3:1, 2 mL) were added
Na2S2O4 (120 mg, 0.69 mmol) and NaHCO3 (64 mg, 0.75 mmol),
and the mixture was stirred at 25 °C for 3 h. Then, the mixture was
poured into H2O (10 mL) and extracted with EtOAc (3 × 5 mL), and
the extracts were purified by flash chromatography with silica gel
to give the desired product 3aa; yield: 120 mg (55%). Under N2 at-
mosphere, the adduct 3aa (120 mg, 0.275 mmol) was dissolved in
THF (5 mL) and the solution was cooled to 0 °C. n-BuLi (1 equiv)
was added to the solution, which was stirred for 30 min. Then, the
mixture was stirred at r.t. for 2 h. The mixture was poured into H2O
(10 mL) and extracted with EtOAc (3 × 5 mL). The extracts were
dried over Na2SO4 and purified by flash chromatography with silica
gel (PE–EtOAc, 4:1) to give 4aa; yield: 25 mg (29%).
MS (EI): m/z (%) = 143 (1) [M+], 101 (42), 58 (58), 43 (100).
HRMS (EI): m/z calcd for C6H9NO3: 143.0582; found: 143.0584.
Allyl tert-Butyl Imidodicarbonate (1c)11
1H NMR (500 MHz, CDCl3): d = 6.92 (br, 1 H), 5.96–5.88 (m, 1 H),
5.36 (dd, J = 17.2, 1.3 Hz, 1 H), 5.26 (dd, J = 10.4, 1.0 Hz, 1 H),
4.66 (d, J = 5.8 Hz, 2 H), 1.47 (s, 9 H).
White solid; mp 104.6–104.9 °C.
IR (KBr): 2994, 1837, 1409, 1301, 1091, 756 cm–1.
Allyl Benzoylcarbamate (1d)
White solid; mp 119.6–120.2 °C.
IR (KBr): 3288, 1752, 1525, 1201, 986, 707 cm–1.
1H NMR (500 MHz, CDCl3): d = 8.07 (br, 1 H), 7.82 (d, J = 7.5 Hz,
2 H), 7.60 (t, J = 7.4 Hz, 1 H), 7.49 (t, J = 7.6 Hz, 2 H), 6.02–5.93
(m, 1 H), 5.41 (d, J = 17.1 Hz, 1 H), 5.31 (d, J = 10.3 Hz, 1 H), 4.74
(d, J = 5.8 Hz, 2 H).
13C NMR (125.8 MHz, CDCl3): d = 165.4, 151.4, 133.7, 133.6,
131.9, 129.6, 128.3, 120.1, 67.5.
1H NMR (500 MHz, CDCl3): d = 4.74–4.68 (m, 1 H), 4.52 (t,
J = 8.7 Hz, 1 H), 4.42–4.34 (m, 2 H), 4.29 (dd, J = 9.5, 3.2 Hz, 1 H),
2.96–2.84 (m, 1 H), 2.54–2.42 (m, 1 H), 1.38 (t, J = 7.1 Hz, 3 H).
13C NMR (125.8 MHz, CDCl3): d = 152.5, 152.2, 124.5–118.1 (m,
2 C), 68.4, 65.7, 51.6, 35.3 (t, J = 20.8 Hz), 15.8.
19F NMR (470 MHz, CDCl3): d = –72.7 (s, 2 F), –112.4 (ddd, JF-F
267.9, 28.2, 4.7 Hz, 1 F), –114.5 (ddd, JF-F = 253.2, 28.2, 9.4 Hz,
=
1 F).
MS (EI): m/z (%) = 205 (10) [M+], 149 (16), 105 (100).
MS (EI): m/z (%) = 309 (1) [M + 2]+, 307 (2) [M+], 282 (9), 280
(26), 86 (100).
HRMS (EI): m/z calcd for C11H11NO3: 205.0739; found: 205.0741.
HRMS (EI): m/z calcd for C9H10NO4F4Cl: 307.0234; found:
307.0236.
Allyl Phenylcarbamate (1e)14
1H NMR (500 MHz, CDCl3): d = 7.39–7.38 (m, 2 H), 7.30 (t,
J = 8.3 Hz, 2 H), 7.06 (t, J = 7.4 Hz, 1 H), 6.90 (br, 1 H), 6.00–5.93
(m, 1 H), 5.35 (dd, J = 17.2, 1.3 Hz, 1 H), 5.26 (dd, J = 10.4, 1.0 Hz,
1 H), 4.66 (d, J = 5.6 Hz, 2 H).
3-Acetyl-4-(3-chloro-2,2,3,3-tetrafluoropropyl)oxazolidin-2-
one (4ba)
Yield: 16 mg (45%); white solid; mp 72.2–72.6 °C.
IR (KBr): 2994, 1801, 1695, 1333, 1035 cm–1.
Allyl Carbamate (1f)15
1H NMR (500 MHz, CDCl3): d = 5.97–5.89 (m, 1 H), 5.32 (dd,
J = 17.2, 1.4 Hz, 1 H), 5.29 (br, 2 H), 5.23 (dd, J = 10.4, 1.1 Hz, 1
H), 4.56 (d, J = 5.6 Hz, 2 H).
1H NMR (500 MHz, CDCl3): d = 4.87–4.81 (m, 1 H), 4.53 (t,
J = 8.8 Hz, 1 H), 4.34 (dd, J = 9.5, 3.2 Hz, 1 H), 2.95–2.83 (m, 1 H),
2.54 (s, 3 H), 2.48–2.36 (m, 1 H).
13C NMR (125.8 MHz, CDCl3): d = 171.9, 154.8, 124.5 (tt,
J = 298.5, 36.9 Hz), 118.1 (tt, J = 254.7, 33.9 Hz), 68.6, 50.7, 34.4
(t, J = 20.7 Hz), 25.3.
19F NMR (470 MHz, CDCl3): d = –72.7 (s, 2 F), –112.6 (ddd, JF-
F = 258.5, 28.2, 4.7 Hz, 1 F), –114.4 (ddd, JF-F = 258.5, 28.2, 9.4 Hz,
1 F).
Ethyl (Allylthio)carbonylcarbamate (1g)
Light yellow liquid.
IR (KBr): 3273, 2982, 1753, 1675, 1215 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.56 (br, 1 H), 5.86–5.83 (m, 1 H),
5.28 (dd, J = 16.9, 1 Hz, 1 H), 5.14 (d, J = 10.0 Hz, 1 H), 4.24 (q,
J = 7.1 Hz, 2 H), 3.58 (d, J = 6.9 Hz, 2 H), 1.31 (t, J = 7.1 Hz, 3 H).
13C NMR (125.8 MHz, CDCl3): d = 169.5, 152.1, 133.4, 119.1,
63.4, 33.3, 14.9.
MS (EI): m/z (%) = 279 (19) [M + 2]+, 277 (56) [M+], 251 (31), 249
(100), 236 (73).
HRMS (EI): m/z calcd for C8H8NO3F4Cl: 277.0129; found:
277.0131.
MS (EI): m/z (%) = 189 (5) [M+], 116 (11), 100 (20), 74 (100).
HRMS (EI): m/z calcd for C7H11NO3S: 189.0460; found: 189.0462.
3-Benzoyl-4-(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)ox-
azolidin-2-one (4db)
Yield: 58 mg (65%); white solid; mp 143.3–143.7 °C.
IR (KBr): 3423, 1797, 1686, 1211, 1145 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.60 (d, J = 7.4 Hz, 2 H), 7.51 (t,
J = 7.5 Hz, 1 H), 7.38 (t, J = 7.8 Hz, 2 H), 4.96 (td, J = 13.9, 2.2 Hz,
1 H), 4.40 (t, J = 8.8 Hz, 1 H), 4.28 (t, J = 7.8 Hz, 1 H), 3.09–2.98
(m, 1 H), 2.45–2.33 (m, 1 H).
tert-Butyl 3,3-Dimethylpent-4-enoylcarbamate (1h)
White solid; mp 79.8–80.6 °C.
IR (KBr): 3271, 1754, 1521, 1156 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.31 (br, 1 H), 5.99–5.94 (m, 1 H),
5.03–4.97 (m, 1 H + 1 H), 2.72 (s, 2 H), 1.49 (s, 9 H), 1.17 (s, 6 H).
13C NMR (125.8 MHz, CDCl3): d = 172.7, 150.9, 147.5, 111.9,
83.0, 47.9, 37.2, 28.7, 27.6.
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13C NMR (125.8 MHz, CDCl3): d = 168.7, 151.5, 132.0, 131.3,
128.3, 127.0, 119.8–107.1 (m, 6 C), 66.3, 48.8, 31.9 (t, J = 20.4 Hz).
19F NMR (470 MHz, CDCl3): d = –81.7 (t, J = 9.4 Hz, 3 F), –112.9
to –114.4 (m, 2 F), –122.7 (s, 2 F), –123.8 (s, 2 F), –124.3 (s, 2 F),
–127.0 (s, 2 F).
19F NMR (470 MHz, CDCl3): d = –81.7 (t, J = 9.6 Hz, 3 F), –112.9
to –114.4 (m, 2 F), –122.5 (s, 2 F), –122.8 (s, 4 F), –123.7 (s, 2 F),
–124.4 (s, 2 F), –127.1 (s, 2 F).
MS (EI): m/z (%) = 591 (3) [M+], 564 (25), 86 (100).
HRMS (EI): m/z calcd for C15H10NO4F17: 591.0338; found:
591.0343.
MS (EI): m/z (%) = 523 (6) [M+], 105 (100).
HRMS (EI): m/z calcd for C17H10NO3F13: 523.0453; found:
523.0454.
Ethyl 4-[2-(Diethoxyphosphoryl)-2,2-difluoroethyl]-2-oxo-
oxazolidine-3-carboxylate (4ad)
Yield: 124 mg (69%); yellow liquid.
IR (KBr): 2987, 1829, 1727, 1376, 1279, 1171, 1021 cm–1.
Diethyl 2-(3-Benzoyl-2-oxooxazolidin-4-yl)-1,1-difluoroethyl-
phosphonate (4dd)
Yield: 49 mg (67%); yellow liquid.
IR (KBr): 2986, 1792, 1683, 1319, 1021 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.66 (d, J = 7.4 Hz, 2 H), 7.56 (t,
J = 7.5 Hz, 1 H), 7.43 (t, J = 7.7 Hz, 2 H), 5.10–5.06 (m, 1 H), 4.65
(t, J = 8.8 Hz, 1 H), 4.38–4.27 (m, 5 H), 3.09–2.98 (m, 1 H), 2.49–
2.35 (m, 1 H), 1.43–1.39 (m, 6 H).
1H NMR (500 MHz, CDCl3): d = 4.80–4.76 (m, 1 H), 4.48 (t,
J = 8.7 Hz, 1 H), 4.40–4.27 (m, 7 H), 2.86–2.79 (m, 1 H), 2.48–2.40
(m, 1 H), 1.42–1.34 (m, 9 H).
13C NMR (125.8 MHz, CDCl3): d = 152.0, 151.3, 123.1–116.3 (m,
1 C), 67.9, 65.7 (d, J = 6.7 Hz), 64.5, 50.9, 37.5 (t, J = 17.3 Hz),
17.1, 14.9.
13C NMR (125.8 MHz, CDCl3): d = 169.8, 152.9, 132.8, 129.2,
127.9, 120.1 (t, J = 260.8 Hz), 118.4 (t, J = 260.7 Hz), 67.7, 65.1 (t,
J = 7.2 Hz), 50.3, 36.4 (q, J = 14.9 Hz), 16.4.
19F NMR (470 MHz, CDCl3): d = –109.7 (dddd, JF-F = 300.8, 103.4,
28.2, 9.4 Hz, 1 F), –112.9 (ddq, JF-F = 300.8, 103.4, 14.1 Hz, 1 F).
19F NMR (470 MHz, CDCl3): d = –110.6 (dddd, JF-F = 300.8, 98.7,
23.5, 9.4 Hz, 1 F), –112.8 (ddq, JF-F = 305.5, 108.4, 14.1 Hz, 1 F).
MS (EI): m/z (%) = 360 (4) [M + 1]+, 316 (27), 178 (100).
HRMS (EI): m/z [M + H]+ calcd for C12H21NO7F2P: 360.1024;
found: 360.1027.
MS (EI): m/z (%) = 391 (1) [M+], 286 (35), 105 (100), 77 (25).
3-Acetyl-4-(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)oxazo-
lidin-2-one (4bb)
Yield: 143 mg (62%); white solid; mp 91.4–91.9 °C.
HRMS (EI): m/z calcd for C16H20NO6F2P: 391.0996; found:
391.0998.
Ethyl 2-Oxo-4-(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl)ox-
azolidine-3-carboxylate (4ab); Typical One-Pot Procedure
Under N2 atmosphere, carbamate 1a (87 mg, 0.5 mmol), CF3(CF2)5I
(2b; 446 mg, 1 mmol) and AIBN (10 mg) were added to a Schlenk
tube, and the mixture was stirred at 80 °C. After 2 h, the reaction
mixture was cooled to 0 °C. NaH (1 equiv) in anhyd THF (5 mL)
was added to the mixture, which was then stirred for 30 min. Then,
the mixture was stirred at r.t. for 2 h. The mixture was poured into
H2O (10 mL) and extracted with EtOAc (3 × 5 mL). The extracts
were dried over Na2SO4 and purified by flash chromatography with
silica gel (PE–EtOAc, 4:1) to give 4ab; yield: 201 mg (82%).
IR (KBr): 3390, 1803, 1703, 1146, 1035 cm–1.
1H NMR (500 MHz, CDCl3): d = 4.78 (td, J = 7.8, 2.6 Hz, 1 H),
4.47 (t, J = 8.8 Hz, 1 H), 4.26 (dd, J = 9.6, 3.2 Hz, 1 H), 2.88–2.76
(m, 1 H), 2.47 (s, 3 H), 2.43–2.28 (m, 1 H).
13C NMR (125.8 MHz, CDCl3): d = 170.9, 153.5, 118.9–109.2 (m,
6 C), 67.7, 49.4, 33.7 (t, J = 20.2 Hz), 24.4.
19F NMR (470 MHz, CDCl3): d = –81.7 (t, J = 9.4 Hz, 3 F), –112.9
to –114.4 (m, 2 F), –122.7 (s, 2 F), –123.8 (s, 2 F), –124.4 (s, 2 F),
–127.1 (s, 2 F).
MS (EI): m/z (%) = 461 (97) [M+], 433 (97), 420 (100).
White solid; mp 85.8–86.3 °C.
IR (KBr): 2992, 1844, 1143, 1069 cm–1.
HRMS (EI): m/z calcd for C12H8NO3F13: 461.0297; found:
461.0298.
1H NMR (500 MHz, CDCl3): d = 4.76–4.70 (m, 1 H), 4.53 (t,
J = 8.7 Hz, 1 H), 4.43–4.34 (m, 2 H), 4.29 (dd, J = 9.5, 3.2 Hz, 1 H),
2.94–2.84 (m, 1 H), 2.52–2.45 (m, 1 H), 1.38 (t, J = 7.1 Hz, 3 H).
13C NMR (125.8 MHz, CDCl3): d = 151.5, 151.2, 118.9–109.2 (m,
6 C), 67.5, 64.8, 50.4, 34.6 (t, J = 20.9 Hz), 14.8.
3-Acetyl-4-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-heptadecafluoro-
nonyl)oxazolidin-2-one (4bc)
Yield: 219 mg (78%); white solid; mp 105.9–106.9 °C.
IR (KBr): 2924, 1804, 1704, 1198, 1035, 651 cm–1.
1H NMR (500 MHz, CDCl3): d = 4.88–4.83 (m, 1 H), 4.54 (t,
J = 8.8 Hz, 1 H), 4.34 (dd, J = 9.6, 3.2 Hz, 1 H), 2.95–2.84 (m, 1 H),
2.55 (s, 3 H), 2.48–2.35 (m, 1 H).
13C NMR (125.8 MHz, CDCl3): d = 170.9, 153.5, 121.2–108.9 (m,
8 C), 67.7, 49.5, 33.7 (t, J = 20.4 Hz), 24.4.
19F NMR (470 MHz, CDCl3): d = –81.7 (t, 3 F), –113.0 to –114.3
(m, 2 F), –122.5 (s, 2 F), –122.8 (s, 4 F), –123.6 (s, 2 F), –124.3 (s,
2 F), –127.0 (s, 2 F).
19F NMR (470 MHz, CDCl3): d = –81.6 (t, J = 9.4 Hz, 3 F), –112.8
to –114.4 (m, 2 F), –122.7 (s, 2 F), –123.8 (s, 2 F), –124.4 (s, 2 F),
–127.0 (s, 2 F).
MS (EI): m/z (%) = 491 (4) [M+], 464 (27), 86 (100).
HRMS (EI): m/z calcd for C13H10NO4F13: 491.0402; found:
491.0403.
Ethyl 4-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-Heptadecafluorononyl)-
2-oxooxazolidine-3-carboxylate (4ac)
Yield: 195 mg (66%); white solid; mp 105.4–106.3 °C.
IR (KBr): 2994, 1846, 1203, 1150, 651 cm–1.
MS (EI): m/z (%) = 561 (10) [M+], 533 (11), 43 (100).
HRMS (EI): m/z calcd for C14H8NO3F17: 561.0233; found:
561.0236.
1H NMR (500 MHz, CDCl3): d = 4.76–4.72 (m, 1 H), 4.54 (t,
J = 8.6 Hz, 1 H), 4.44–4.32 (m, 2 H), 4.28 (d, J = 9.6 Hz, 1 H),
2.96–2.84 (m, 1 H), 2.55–2.43 (m, 1 H), 1.38 (t, J = 7.1 Hz, 3 H).
13C NMR (125.8 MHz, CDCl3): d = 151.5, 151.2, 120.3–108.9 (m,
8 C), 67.5, 64.7, 50.4, 34.6 (t, J = 20.3 Hz), 14.7.
Diethyl 2-(3-Acetyl-2-oxooxazolidin-4-yl)-1,1-difluoroethyl-
phosphonate (4bd)
Yield: 107 mg (65%); yellow liquid.
IR (KBr): 2988, 1790, 1707, 1295, 1022 cm–1.
Synthesis 2011, No. 22, 3627–3634 © Thieme Stuttgart · New York

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One-Pot Synthesis of 4-(Fluoroalkyl)oxazolidin-2-ones from Allyl Carbamates
3633
1H NMR (500 MHz, CDCl3): d = 4.93–4.89 (m, 1 H), 4.49 (t,
J = 8.8 Hz, 1 H), 4.38–4.27 (m, 5 H), 2.88–2.76 (m, 1 H), 2.53 (s, 3
H), 2.43–2.32 (m, 1 H), 1.43–1.38 (m, 6 H).
4-[2-(4-Chlorophenylthio)-2,2-difluoroethyl]oxazolidin-2-one
(5af)
Yield: 75 mg (51%); yellow solid; mp 110.4–111.1 °C.
13C NMR (125.8 MHz, CDCl3): d = 170.8, 153.9, 121.1 (t,
J = 260.8 Hz), 119.4 (t, J = 260.7 Hz), 68.0, 65.6, 49.9, 36.6 (q,
J = 19.5 Hz), 24.4, 17.0.
19F NMR (470 MHz, CDCl3): d = –110.0 (dddd, JF-F = 300.8, 103.4,
28.2, 9.4 Hz, 1 F), –112.7 (ddq, JF-F = 300.8, 103.4, 14.1 Hz, 1 F).
IR (KBr): 3247, 1750, 1251, 1168, 1028, 954, 721 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.53 (d, J = 8.4 Hz, 2 H), 7.40 (d,
J = 8.4 Hz, 2 H), 5.34 (br, 1 H), 4.58 (t, J = 8.6 Hz, 1 H), 4.32–4.26
(m, 1 H), 4.07–4.04 (m, 1 H), 2.52–2.34 (m, 2 H).
13C NMR (125.8 MHz, CDCl3): d = 159.1, 138.2, 137.9, 130.4,
126.1 (t, J = 278.4 Hz), 70.1, 48.5, 44.5 (t, J = 23.2 Hz).
MS (EI): m/z (%) = 330 (1) [M + 1]+, 286 (33), 138 (65), 106 (100).
HRMS (EI): m/z [M + H]+ calcd for C11H19NO6F2P: 330.0918;
found: 330.0919.
19F NMR (470 MHz, CDCl3): d = –73.4 (t, J = 14.3 Hz, 2 F).
MS (EI): m/z (%) = 295 (35) [M + 2]+, 293 (100) [M+], 149 (80), 86
(97).
tert-Butyl 2-Oxo-4-(2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluorohep-
tyl)oxazolidine-3-carboxylate (4cb)
Yield: 151 mg (58%); white solid; mp 104.8–106.6 °C.
HRMS (EI): m/z calcd for C11H10NO2F2ClS: 293.0089; found:
293.0089.
IR (KBr): 3421, 1841, 1201, 1144 cm–1.
1H NMR (500 MHz, CDCl3): d = 4.69–4.66 (m, 1 H), 4.49 (t,
J = 8.4 Hz, 1 H), 4.23 (dd, J = 9.4, 2.7 Hz, 1 H), 2.89–2.78 (m, 1 H),
2.54–2.42 (m, 1 H), 1.56 (s, 9 H).
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synthesis.
13C NMR (125.8 MHz, CDCl3): d = 151.8, 149.3, 120.0–111.1 (m,
6 C), 85.8, 67.2, 50.3, 34.6 (t, J = 20.1 Hz), 28.6.
19F NMR (470 MHz, CDCl3): d = –81.7 (t, J = 9.4 Hz, 3 F), –112.8
to –114.4 (m, 2 F), –122.7 (s, 2 F), –123.8 (s, 2 F), –124.4 (s, 2 F),
–127.0 (s, 2 F).
Acknowledgment
This work was supported by the National Natural Science Founda-
tion of China (No. 20972050, No. 21172148) and the Science
and Technology Commission of Shanghai Municipality (No.
10540501300).
MS (EI): m/z (%) = 504 (7) [M – CH3]+, 420 (47), 402 (51), 57
(100).
References
HRMS (EI): m/z [M – CH3]+ calcd for C14H11NO4F13: 504.0481;
found: 504.0482.
(1) (a) Harding, K. E.; Tiner, T. H. In Comprehensive Organic
Synthesis, Vol. 4; Trost, B. M., Ed.; Pergamon Press: New
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tert-Butyl 4-[2-(Diethoxyphosphoryl)-2,2-difluoroethyl]-2-
oxooxazolidine-3-carboxylate (4cd)16
Yield: 97 mg (50%); yellow liquid.
1H NMR (500 MHz, CDCl3): d = 4.71–4.69 (m, 1 H), 4.44 (t,
J = 8.2 Hz, 1 H), 4.33–4.25 (m, 5 H), 2.78–2.71 (m, 1 H), 2.48–2.40
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4-[2,2-Difluoro-2-(phenylthio)ethyl]oxazolidin-2-one (5ae);
Typical One-Pot Procedure
To a mixture of carbamate 1a (87 mg, 0.5 mmol) and PhSCF2I (2e;
158 mg, 0.55 mmol) in MeCN–H2O (3:1, 2 mL) were added
Na2S2O4 (120 mg, 0.69 mmol) and NaOH (30 mg, 0.75 mmol), and
the mixture was stirred at 25 °C; the reaction was monitored by
TLC. When the reaction was completed, the mixture was concen-
trated and purified by flash chromatography with silica gel (PE–
EtOAc, 4:1) to give 5ae; yield: 73 mg (56%).
(c) Selvakumar, N.; Srinivas, D.; Khera, M. K.; Kumar, M.
S.; Mamidi, N. V. S. R.; Sarnaik, H.; Chandrasekar, C.; Rao,
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J. Med. Chem. 2002, 45, 3953; and references cited therein.
(d) Mallesham, B.; Rajesh, B. M.; Reddy, P. R.; Srinivas, D.;
Trehan, S. Org. Lett. 2003, 5, 963.
Yellow liquid.
IR (KBr): 3283, 1760, 1410, 1257, 973, 752 cm–1.
1H NMR (500 MHz, CDCl3): d = 7.60 (d, J = 7.5 Hz, 2 H), 7.49–
7.40 (m, 3 H), 5.22 (br, 1 H), 4.57 (t, J = 8.6 Hz, 1 H), 4.33–4.27 (m,
1 H), 4.06–4.02 (m, 1 H), 2.52–2.32 (m, 2 H).
13C NMR (125.8 MHz, CDCl3): d = 160.4, 137.9, 131.1, 129.9 (t,
J = 278.4 Hz), 127.3, 71.2, 49.6, 45.5 (t, J = 23.2 Hz).
(8) (a) Uneyama, K. Organofluorine Chemistry; Blackwell:
Oxford, 2006. (b) Bégué, J.-P.; Bonnet-Delpon, D.
Bioorganic and Medicinal Chemistry of Fluorine; Wiley:
Hoboken, 2008. (c) Special Issue on Fluorine in the Life
Sciences, ChemBioChem 2004, 5, 557-726. (d) Purser, S.;
Moore, P. R.; Swallow, S.; Gouverneur, V. Chem. Soc. Rev.
2008, 37, 320.
19F NMR (470 MHz, CDCl3): d = –73.4 (td, J = 14.6, 6.1 Hz, 2 F).
MS (EI): m/z (%) = 259 (75) [M+], 149 (100), 110 (65), 86 (37).
HRMS (EI): m/z calcd for C11H11NO2F2S: 259.0479; found:
(9) Haga, T.; Toki, T.; Koyanagi, T.; Okada, H.; Yoshida, K.;
259.0479.
Imai, O. EP 146748, 1984.
(10) Truong, V. L.; Gauthier, J. Y.; Boyd, M.; Roy, B.; Scheigetz,
J. Synlett 2005, 1279.
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X.-Y. Yang et al.
PAPER
(11) Chong, J. M.; Park, S. B. J. Org. Chem. 1993, 58, 7300.
(12) Fang, X.; Yang, X. Y.; Yang, X. J.; Mao, S. J.; Wang, Z. H.;
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Synthesis 2011, No. 22, 3627–3634 © Thieme Stuttgart · New York