Synthesis of tert -Butyl 1,3-Diaryl-3-oxopropylcarbamates by a regiocontrolled reduction of ketoaziridines

Article abstract of DOI:10.1055/s-0034-1379029

A new, convenient approach for the reductive ring opening of N-H ketoaziridines is described. Treatment of N-H ketoaziridines with di-tert-butyl dicarbonate [(Boc)₂O] in the presence of sodium iodide and nickel(II) chloride results in the corresponding tert-butyl 1,3-diaryl-3-oxopropylcarbamates by a regiocontrolled reaction. The structure of the regioisomeric product was confirmed by X-ray crystal structure analysis.

Full text of DOI:10.1055/s-0034-1379029

SYNTHESIS
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X
©
Georg Thieme Verlag Stuttgart · New York
2015, 47, 0129–0133
129
paper
Synthesis
H. A. Samimi et al.
Paper
Synthesis of tert-Butyl 1,3-Diaryl-3-oxopropylcarbamates by a
Regiocontrolled Reduction of Ketoaziridines
Regioselective Reduction of Ketoaziridines
Heshmat A. Samimi*a
Bohari M. Yaminb
Fatemeh Saberia
O
O
t-BuO
Ar1
O
NiCl , NaI
2
N
t-BuO
NH
O
H
O
(Boc)2O
regioselective
regioselective
Ar2
a
N
Ar1
Ar2
Faculty of Science, Department of Chemistry, Shahrekord
University, PO Box 115, Shahrekord, Iran
samimi-h@sci.sku.ac.ir
School of Chemical Sciences and Food Technology, University
Ar1
Ar2
Ph
O
b
Kebangsaan Malaysia, UKM 43500 Bangi Selangor, Malaysia
+
9
8
3
(
8
1
4
)
4
2
4
4
1
9
PhCOCl
Et3N
O
O
Ph
Ar1
O
N
N
NiCl2, NaI
Ar2
Ar2
Ar1
Received: 03.07.2014
Accepted after revision: 06.08.2014
Published online: 17.09.2014
Previous reports have shown that replacement of the
hydrogen of the N–H moiety with an electron-withdrawing
DOI: 10.1055/s-0034-1379029; Art ID: ss-2014-z0402-op
substituent increases the susceptibility of N-H aziridines to
ring-opening or ring-enlargement reactions.2
8–30
So, our
Abstract A new, convenient approach for the reductive ring opening
of N-H ketoaziridines is described. Treatment of N-H ketoaziridines with
first aim was to synthesize N-Boc-substituted ketoaziri-
dines as a precursor for preparation of the corresponding
nitrogen-containing compounds via ring opening or ring
enlargement. At first, we investigated the reaction of di-
di-tert-butyl dicarbonate [(Boc) O] in the presence of sodium iodide
2
and nickel(II) chloride results in the corresponding tert-butyl 1,3-diaryl-
3-oxopropylcarbamates by a regiocontrolled reaction. The structure of
the regioisomeric product was confirmed by X-ray crystal structure
analysis.
tert-butyl dicarbonate [(Boc) O] and 2-(4-chlorobenzoyl)-
2
3
-(4-chlorophenyl)aziridine (1a) in chloroform, acetoni-
trile, ethanol or acetone in the presence of triethylamine.
The mixture was stirred for 10 hours under refluxing condi-
tions, but 1a was recovered unchanged (Table 1, entries 1–
Key words aziridines, regioselectivity, ring opening, reduction, nick-
el(II) chloride
4); none of the desired product was detected.
The reductive ring opening of aziridines is a synthetical-
ly useful transformation for the preparation of amino com-
pounds, especially in the synthesis of β-amino ketones,1
which are important for the synthesis of biologically active
Based on the well-documented transformation of N-
acyl- or N-Boc-substituted aziridines into oxazolines in the
,2
31–34
20,21
literature
and our success
with the ring-expansion
reaction of N-acyl-substituted aziridines with sodium io-
3–7
compounds.
dide, we envisioned that ring expansion of 1a with (Boc) O
2
Several methods are known for the synthesis of β-ami-
no ketones from the ring opening of aziridines. A literature
survey shows the few reducing agents, including Raney
in the presence of sodium iodide might be similarly
achieved to give oxazolidin-2-one 6a in a one-pot reaction.
Thus, we examined the reaction of aziridine 1a with
8
9
nickel in ethanol, Pearlman’s catalyst [Pd(OH) /C], Adam’s
(Boc) O in the presence of sodium iodide in acetone for
2
2
1
0
11
catalyst (PtO /HCO H), sodium borohydride, tributyltin
achieving this aim; however, no reaction occurred, even un-
der refluxing conditions (Table 1, entry 5).
In order to evaluate the effect of a Lewis acid in this re-
action, we tried the reaction of 2-(4-chlorobenzoyl)-3-(4-
2
2
1
2
13
hydride, poly(methylhydrosiloxane) (PMHS), silyllithium
1
4
15
16
reagents, magnesium and lithium metal reagents, tita-
nium tetraiodide, samarium(II) iodide and visible-light
photoredox ruthenium catalysts, for the reductive ring
opening of aziridines. None of these methods, however, re-
sult in a direct reduction reaction of N-H aziridines to give
derivatives of β-carbamato ketones.
1
7
18
19
chlorophenyl)aziridine (1a) with (Boc) O in the presence of
2
sodium iodide and some Lewis acids (ZnCl , CuCl ) in re-
2
2
fluxing acetone; with zinc chloride and copper(II) chloride,
a new product 4a was obtained in low yields (Table 1, en-
tries 6 and 7).
Our recent interest in the ring opening and ring expan-
sion of ketoaziridines motivated us to synthesize tert-butyl
In another attempt, we examined the reaction of 1a
1
,3-diaryl-3-oxopropylcarbamates.20–27
with (Boc) O in the presence of nickel(II) chloride and sodi-
2
um iodide (1 mmol) (Table 1, entry 8). At this stage, thin-
layer chromatography confirmed the formation of a new
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30
Synthesis
H. A. Samimi et al.
Paper
Table 1 Optimization of the Conditions for the Reaction of Aziridine 1a with (Boc) Oa
2
H
N
O
Cl
O
O
t-BuO
N
H
1
a
Cl
Cl
O
O
+
O
solvent
Cl
O
t-BuO
N
Lewis acid
NaI
H
5a
4
a
chalcone
t-BuO
O
Ot-Bu
formed
Cl
3a
Cl not formed
Lewis acid
NaI
X
O
O
t-BuO
O
NH
O
N
6a
4-ClC6H4
C6H4Cl-4
4-ClC H
O
not formed
6
4
2a
4-ClC6H4
b
Entry
Reagent
Solvent
Time (h)
Yield (%)
3
a
4a
1c
2c
3c
4c
5c
6
Et
Et
Et
Et
N
N
N
N
CHCl
10
10
10
10
6
0
0
3
3
3
3
3
MeCN
0
0
EtOH
0
0
acetone
acetone
acetone
acetone
acetone
acetone
acetone
acetone
0
0
NaI
0
0
NaI, ZnCl
2
8
0
16
23
71
0
7
NaI, CuCl
NaI, NiCl
ZnCl
CuCl
NiCl
O/reagent = 1:1:1.
2
8
0
8
2
8
19
0
9c
10
10
10
2
1
0c
1
2
0
0
1
2
44
0
a
b
c
1
a/(Boc)
2
Isolated yields.
The starting material was recovered.
compound, along with the corresponding chalcone 3a. The
crude product was purified by column chromatography,
surprisingly to provide tert-butyl 1,3-bis(4-chlorophenyl)-
A further examination of the reaction of 1a and (Boc) O
2
with zinc chloride, copper(II) chloride or nickel(II) chloride
in the absence of sodium iodide failed to give any product
4a (Table 1, entries 9–11).
3-oxopropylcarbamate (4a) or tert-butyl 2,3-bis(4-chloro-
phenyl)-3-oxopropylcarbamate (5a). Since the spectroscop-
ic data were not conclusive for 4a or 5a, X-ray crystallo-
graphic analysis was conducted to verify the product struc-
ture as 4a (Figure 1).
It is striking to note that X-ray crystal structure analysis
of the representative product 4a (Figure 1) confirms the re-
giocontrolling nature of this reaction. The reaction pro-
ceeded with selective ring opening at the C–N bond α to the
benzoyl moiety, whereas the C–N bond of the benzyl group
was not cleaved. The same stereochemistry has been gener-
alized for all other products formed from this reaction.
To expand the scope of this novel method, several sub-
stituted ketoaziridines 1 were reacted with (Boc) O in the
2
presence of nickel(II) chloride and sodium iodide, resulting
in production of the tert-butyl 1,3-diaryl-3-oxopropylcar-
bamates 4 in moderate to good yields (Table 2). All the
1
13
products were characterized by H NMR, C NMR and IR
spectroscopy.
We have previously reported the mechanism of the io-
dide ion catalyzed isomerization of N-acyl-substituted
aziridines by attack of the nucleophile at C-2 of the aziri-
dine and subsequent cyclization to the corresponding oxaz-
olines.20 We have now found that the action of nickel(II)
chloride with sodium iodide on 2-aroyl-3-arylaziridines is
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Synthesis
H. A. Samimi et al.
Paper
Table 3 Substrate Scope for the Ring Expansion of N-H Ketoaziridines
1
to the Corresponding Oxazolines 7
Ph
O
H
O
PhCOCl
Et3N
NiCl2
NaI
N
O
N
Ph
N
O
Ar1
Ar2
1
Ar1
Ar2
Ar1
Ar2
O
a–c
regioselective
7
a
Product
Ar1
2,4-Cl
Ar2
Ph
Time (h)
Yield (%)
7
7
a
b
c
2
C
6
H
3
6
8
8
77
4-ClC
6
H
4
4-ClC
6
H
4
74
7
Ph
Ph
7320
a
Isolated yields.
stereocontrolled ring-expansion reaction, while N-Boc-sub-
stituted ketoaziridines produce tert-butyl 1,3-diaryl-3-oxo-
propylcarbamates 4 through a reductive ring-opening reac-
tion. This shows the influence of the N-substituent on the
ring expansion or reductive ring opening of ketoaziridines.
The exact mechanism of the novel reductive ring-open-
ing reaction is not clear. Research in this respect is under
way.
Figure 1 ORTEP view of the crystal structure of 4a
Table 2 Substrate Scope for the Reductive Ring Opening of N-H Keto-
aziridines 1 to the Corresponding tert-Butyl 1,3-Diaryl-3-oxopropylcar-
a
bamates 4
O
In conclusion, we have disclosed the highly efficient, re-
ductive ring opening of N-H ketoaziridines under refluxing
conditions via a regioselective reaction promoted with
H
O
N
t-BuO
NH
O
NiCl2, NaI
acetone
Ar1
Ar2
+ (Boc)2O
Ar1
Ar2
(
Boc) O in the presence of nickel(II) chloride and sodium io-
2
1
4
dide as an inexpensive reagent system.
Product Ar1
Ar2
Time (h)
Yield (%)
b
4
4
4
4
4
4
4
4
a
b
c
4-ClC
6
H
4
4-ClC
6
H
4
8
71
68
73
78
76
62
73
56
All yields refer to isolated products after purification by column chro-
matography or by distillation under reduced pressure. Products were
characterized by comparison with authentic samples (IR and H NMR
3-O NC
2
6
H
3
Ph
10
1
4-ClC
6
H
4
Ph
8
spectra, TLC, melting and boiling points). NMR spectra were recorded
d
e
f
Ph
Ph
12
1
in CDCl on a Bruker AMX-400 spectrometer ( H NMR at 400 MHz and
3
13
2,4-Cl
2C
6
H
3
4-ClC
4-ClC
Ph
6
H
4
4
10
C NMR at 100 MHz) with chemical shift values (δ) in ppm downfield
from TMS. IR spectra were recorded on a JASCO FT/IR-6300 spectrom-
eter. All solvents used were dried and distilled according to standard
procedures.
3-O
2,4-Cl
4-BrC
2
NC
6
H
3
6
H
12
g
h
2
C
6
H
3
8
10
6
H
4
Ph
a
tert-Butyl 1,3-Diaryl-3-oxopropylcarbamates 4a–h (Table 2); Gen-
eral Procedure
Refluxing conditions with 1/(Boc)
Isolated yields.
2
O/NiCl
2
/NaI = 1:1:1:1.
b
NiCl (1.0 mmol) and NaI (1.0 mmol) were added to a solution of the
2
ketoaziridine 1 (1.0 mmol) and (Boc) O (1.0 mmol) in acetone (15
2
the same as that of iodide, also involving a regio- and ste-
reocontrolled ring-expansion process. To test the scope of
this novel method, substituted ketoaziridines 1 were react-
ed with benzoyl chloride in the presence of nickel(II) chlo-
ride and sodium iodide, which resulted in the production of
oxazolines 7 in moderate to good yields (Table 3); no trace
of another regioisomer was detected. All the products were
characterized by H NMR, C NMR and IR spectroscopy.
A striking feature of this process is that N-acyl-substi-
tuted ketoaziridines, in the presence of nickel(II) chloride
and sodium iodide, result in oxazolines 7 via a regio- and
mL). The mixture was refluxed for 8–12 h. The crude product was pu-
rified by column chromatography (silica gel; EtOAc–hexane, 2:5) to
provide the desired corresponding tert-butyl 3-oxopropylcarbamate
4
; yield: 56–78%.
tert-Butyl 1,3-Bis(4-chlorophenyl)-3-oxopropylcarbamate (4a)
Yield: 279 mg (71%); white solid; mp 140–142 °C.
1
13
IR (KBr): 3280, 1685, 1596, 1452, 1321, 1228 cm–1
.
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32
Synthesis
H. A. Samimi et al.
Paper
1
H NMR (400 MHz, CDCl ): δ = 1.34 (s, 9 H), 3.31 (dd, J = 16.8, 6.1 Hz, 1
tert-Butyl 3-(4-Chlorophenyl)-1-(3-nitrophenyl)-3-oxopropylcar-
3
H), 3.55 (br d, 1 H), 5.12 (br d, 1 H), 5.48 (br, 1 H), 7.20 (m, 4 H), 7.35
bamate (4f)
(
1
d, J = 8.6 Hz, 2 H), 7.76 (d, J = 8.6 Hz, 2 H).
Yield: 250 mg (62%); red oil.
IR (KBr): 3294, 1681, 1591, 1355, 1452, 1345, 1228 cm–1
3
C NMR (100 MHz, CDCl ): δ = 28.3, 44.0, 50.8, 79.9, 127.7, 128.7,
3
.
1
29.0, 129.1, 129.5, 133.1, 134.8, 140.0, 155.1, 196.6.
1
H NMR (400 MHz, CDCl ): δ = 1.35 (s, 9 H), 3.41 (dd, J = 17.1, 5.7 Hz, 1
3
Anal. Calcd for C20H21Cl NO : C, 60.92; H, 5.37; N, 3.55. Found: C,
6
2
3
H), 3.61 (br d, 1 H), 5.27 (br d, 1 H), 5.67 (br, 1 H), 7.35 (d, J = 8.7 Hz, 2
H), 7.41–7.45 (d, J = 8.0 Hz, 1 H), 7.63 (d, J = 7.2 Hz, 1 H), 7.78 (d, J = 8.7
Hz, 2 H), 8.02 (dd, J = 8.0, 1.2 Hz, 1 H), 8.40 (s, 1 H).
13
0.89; H, 5.39; N, 3.59.
tert-Butyl 1-(3-Nitrophenyl)-3-oxo-3-phenylpropylcarbamate
4b)
C NMR (100 MHz, CDCl ): δ = 28.3, 43.4, 50.5, 80.3, 121.2, 122.4,
3
(
122.9, 129.1, 129.4, 129.5, 132.8, 134.5, 140.3, 148.4, 155.1, 193.8.
Yield: 251 mg (68%); white solid; mp 138–140 °C.
IR (KBr): 3310, 1688, 1594, 1535, 1458, 1324, 1350 cm–1
Anal. Calcd for C20H21ClN O : C, 59.53; H, 5.23; N, 6.92. Found: C,
59.53; H, 5.41; N, 6.84.
2
5
.
1
H NMR (400 MHz, CDCl ): δ = 1.35 (s, 9 H), 3.43 (dd, J = 17.3, 5.4 Hz, 1
3
H), 3.63 (br d, 1 H), 5.26 (br d, 1 H), 5.78 (br, 1 H), 7.43 (m, 3 H), 7.50
tert-Butyl 1-(2,4-Dichlorophenyl)-3-oxo-3-phenylpropylcarba-
(td, J = 7.4, 1.3 Hz, 1 H), 7.64 (d, J = 7.1 Hz, 1 H), 7.78 (m, 2 H), 8.11 (dd,
mate (4g)
J = 8.2, 1.3 Hz, 1 H), 8.14 (t, J = 1.9 Hz, 1 H).
Yield: 287 mg (73%); white solid; mp 131–133 °C.
IR (KBr): 3299, 1683, 1584, 1451, 1329, 1220 cm–1
13
C NMR (100 MHz, CDCl ): δ = 28.3, 43.6, 50.5, 80.2, 121.3, 122.3,
3
.
128.0, 128.8, 129.5, 129.6, 132.8, 133.8, 136.2, 148.3, 155.2, 189.8.
1
H NMR (400 MHz, CDCl ): δ = 1.34 (s, 9 H), 3.32 (dd, J = 16.82, 6.13
3
Anal. Calcd for C20H22N O : C, 64.85; H, 5.99; N, 7.56. Found: C, 64.70;
2
5
Hz, 1 H), 3.65 (br d, 1 H), 5.13 (br d, 1 H), 5.54 (br, 1 H), 7.19 (m, 3 H),
H, 6.19; N, 7.69.
7.34 (t, J = 7.67 Hz, 2 H), 7.49 (t, J = 7.2 Hz, 1 H), 7.71 (d, J = 7.48 Hz, 2
H).
tert-Butyl 1-(4-Chlorophenyl)-3-oxo-3-phenylpropylcarbamate
4c)
13
C NMR (100 MHz, CDCl ): δ = 28.3, 43.6, 50.5, 80.3, 121.2, 122.4,
3
(
129.1, 129.3, 129.5, 129.7, 132.8, 140.3, 148.4, 155.1, 193.8.
Yield: 262 mg (73%); white solid; mp 142–144 °C.
IR (KBr): 3310, 1688, 1594, 1459, 1331, 1221 cm–1
Anal. Calcd for C20H21Cl NO : C, 60.92; H, 5.37; N, 3.55. Found: C,
60.84; H, 5.46; N, 3.61.
2
3
.
1
H NMR (400 MHz, CDCl ): δ = 1.34 (s, 9 H), 3.34 (dd, J = 16.8, 5.8 Hz, 1
3
H), 3.56 (br d, 1 H), 5.14 (br d, 1 H), 5.59 (br, 1 H), 7.22 (m, 4 H), 7.35
tert-Butyl 1-(4-Bromophenyl)-3-oxo-3-phenylpropylcarbamate
(t, J = 7.1 Hz, 2 H), 7.47 (t, J = 7.1 Hz, 1 H), 7.78 (t, J = 7.5 Hz, 2 H).
(4h)
13
C NMR (100 MHz, CDCl ): δ = 28.3, 43.9, 50.7, 79.8, 127.7, 128.0,
Yield: 226 mg (56%); white solid; mp 137–139 °C.
3
128.7, 128.8, 132.9, 133.5, 136.5, 140.3, 155.1, 197.8.
IR (KBr): 3288, 1684, 1593, 1458, 1325, 1222 cm–1
.
Anal. Calcd for C20H22ClNO : C, 66.75; H, 6.16; N, 3.89. Found: C,
1
3
H NMR (400 MHz, CDCl ): δ = 1.32 (s, 9 H), 3.32 (dd, J = 16.7, 5.8 Hz, 1
3
66.64; H, 6.24; N, 3.94.
H), 3.55 (br d, 1 H), 5.13 (br d, 1 H), 5.59 (br, 1 H), 7.30–7.55 (m, 4 H),
.37 (t, J = 7.2 Hz, 2 H), 7.75 (t, J = 7.2 Hz, 1 H), 7.8 (d, J = 7.6 Hz, 2 H).
7
tert-Butyl 3-Oxo-1,3-diphenylpropylcarbamate (4d)
13
C NMR (100 MHz, CDCl ): δ = 28.3, 43.9, 50.7, 79.8, 127.7, 128.1,
3
Yield: 253 mg (78%); white solid; mp 135–137 °C.
128.7, 128.8, 132.9, 133.5, 136.5, 140.3, 155.1, 197.8.
IR (KBr): 3289, 1681, 1591, 1449, 1318, 1221 cm–1
.
Anal. Calcd for C20H22BrNO : C, 59.42; H, 5.48; N, 3.46. Found: C,
3
1
59.38; H, 5.61; N, 3.51.
H NMR (400 MHz, CDCl ): δ = 1.34 (s, 9 H), 3.36 (dd, J = 16.6, 6.1 Hz, 1
3
H), 3.57 (br d, 1 H), 5.17 (br d, 1 H), 5.52 (br, 1 H), 7.16 (t, J = 6.9 Hz, 1
H), 7.22 (m, 4 H), 7.34 (t, J = 7.8 Hz, 2 H), 7.46 (t, J = 7.4 Hz, 1 H), 7.80
X-ray Crystal Structure Analysis for 4a
(
1
t, J = 7.1 Hz, 2 H).
Formula: C20H21Cl NO , M = 394.28, yellow crystal 0.50 × 0.15 × 0.01
2
3
3
C NMR (100 MHz, CDCl ): δ = 28.3, 44.2, 51.4, 79.6, 126.3, 127.3,
mm, a = 11.6327(13) Å, b = 19.181(2) Å, c = 9.9585(11) Å, V =
3
3
–3
–1
1
28.1, 128.6, 128.7, 133.3, 136.7, 141.6, 155.2, 190.2.
2039.6(4) Å , ρcalcd = 1.284 mg·cm , μ = 0.337 mm , Z = 4, monoclinic,
λ = 0.71073 Å, T = 296 K, ω and ϕ scans, 3580 reflections collected (±h,
Anal. Calcd for C20H23NO : C, 73.82; H, 7.12; N, 4.30. Found: C, 73.70;
H, 7.15; N, 4.41.
3
±
k, ±l) [I ≥ 2σ(I)], 1959 independent (Rint = 0.1319) and 1852 observed
2
reflections [I ≥ 2σ(I)], 242 refined parameters, R = 0.0544, wR
0
=
–3
.1260, max residual electron density 0.24 (–0.29) e·Å , Flack param-
tert-Butyl 3-(4-Chlorophenyl)-1-(2,4-dichlorophenyl)-3-oxopro-
pylcarbamate (4e)
eter 0.0040(6). The data set was collected with a Bruker SMART APEX
CCD area detector diffractometer, absorption correction: multi-scan
Yield: 324 mg (76%); white solid; mp 142–144 °C.
IR (KBr): 3288, 1685, 1599, 1452, 1325, 1220 cm–1
35
(
SADABS ), at the School of Chemical Sciences and Food Technology,
.
University Kebangsaan Malaysia.
1
H NMR (400 MHz, CDCl ): δ = 1.49 (s, 9 H), 3.33 (dd, J = 16.7, 5.4 Hz, 1
3
Oxazolines 7a,b (Table 3); General Procedure
H), 3.55 (br d, 1 H), 5.40 (br d, 1 H), 5.87 (br, 1 H), 7.14 (d, J = 8.6 Hz, 1
H), 7.27 (m, 3 H), 7.33 (t, J = 8.8 Hz, 2 H), 7.74 (d, J = 8.6 Hz, 1 H).
Benzoyl chloride (1.0 mmol) was added dropwise to a solution of an
1
3
aziridine 1 (1.0 mmol) and Et N (2.0 mmol) in CH Cl (10 mL) at 0 °C.
The mixture was stirred for 1.5 h at this temperature and for 4 h at r.t.,
3
2
2
C NMR (100 MHz, CDCl ): δ = 28.3, 43.9, 50.7, 79.8, 127.8, 128.0,
3
1
28.3, 128.7, 128.8, 128.9, 132.9, 133.5, 136.5, 140.3, 155.1, 197.8.
and then rinsed with H O (2 × 10 mL). The organic layer was dried
2
Anal. Calcd for C20H20Cl NO : C, 56.03; H, 4.70; N, 3.27. Found: C,
5
3
3
over anhydrous Na SO and concentrated under reduced pressure.
2
4
6.20; H, 4.85; N, 3.39.
©
Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, 129–133

1
33
Synthesis
H. A. Samimi et al.
Paper
Acetone (15 mL), NaI (1 mmol) and NiCl (1 mmol) were added to the
crude product and the mixture was stirred at 50 °C for 6 h. Then, the
References
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(
(
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mixture was rinsed with H O (2 × 10 mL), and the organic layer was
2
separated and dried with anhydrous Na SO . Evaporation of the sol-
2
4
1
vent under reduced pressure and subsequent purification of the resi-
due by column chromatography (silica gel; EtOAc–hexane, 1:4) pro-
vided the corresponding oxazoline 7.
(
(
(
(
5
4) Fiedler, E.; Fiedler, H.-P.; Gerhard, A.; Keller-Schierlein, W.;
König, W. A.; Zähner, H. Arch. Microbiol. 1976, 107, 249.
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K. V. Bioorg. Med. Chem. Lett. 2008, 18, 4130.
trans-5-Benzoyl-4-(2,4-dichlorophenyl)-2-phenyl-2-oxazoline
(7a)
Yield: 304 mg (77%); white solid; mp 128–130 °C.
6) For general reviews, see: Enantioselective Synthesis of -Amino
Acids; Juaristi, E., Ed.; Wiley-VCH: Weinheim, 1997.
IR (KBr): 3066, 2907, 1680, 1652, 1591, 1481, 1261, 760, 707, 695 cm–1
.
1
(7) Cardillo, G.; Tolomelli, A.; Tomasini, C. J. Org. Chem. 1996, 61,
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H NMR (400 MHz, CDCl ): δ = 5.58 (d, J = 6.7 Hz, 1 H), 5.75 (d, J = 6.7
3
8
Hz, 1 H), 7.36–7.67 (m, 9 H), 7.99 (d, J = 7.3 Hz, 2 H), 8.14 (d, J = 7.3 Hz,
2
(
(
H).
6
13
C NMR (100 MHz, CDCl ): δ = 74.3, 87.4, 127.4, 127.5, 128.3, 128.6,
3
1
1
28.8, 129.2, 129.3, 129.4, 129.5, 132.3, 134.4, 134.6, 141.1, 164.3,
94.9.
6
(
10) Higashiyama, K.; Matsumura, M.; Shiogama, A.; Yamauchi, T.;
Anal. Calcd for C22H15Cl NO : C, 66.68; H, 3.82; N, 3.53. Found: C,
6
2
2
Ohmiya, S. Heterocycles 2002, 58, 85.
6.57; H, 3.84; N, 3.47.
(
(
11) Dauban, P.; Dodd, R. H. Tetrahedron Lett. 1998, 39, 5739.
12) Kim, S.; Jung, M. S.; Cho, C. H.; Schiesser, C. H. Tetrahedron Lett.
2001, 42, 943.
trans-5-(4-Chlorobenzoyl)-4-(4-chlorophenyl)-2-phenyl-2-oxazo-
line (7b)
(13) Chandrasekhar, S.; Ahmed, M. Tetrahedron Lett. 1999, 40, 9325.
(
14) Davis, A. L.; Korous, A. A.; Hartel, A. M. Tetrahedron Lett. 2013,
4, 3673.
15) Pak, C. S.; Kim, T. H.; Ha, S. J. J. Org. Chem. 1998, 63, 10006.
Yield: 292 mg (74%); white solid; mp 135–137 °C.
IR (KBr): 3058, 2921, 1684, 1650, 1594, 1483, 1266, 761, 709, 696 cm–1
5
.
(
1
H NMR (400 MHz, CDCl ): δ = 5.50 (d, J = 6.5 Hz, 1 H), 5.70 (d, J = 6.5
3
(16) Almena, J.; Foubelo, F.; Yus, M. J. Org. Chem. 1994, 59, 3210.
17) Shimizu, M.; Kurokawa, H.; Nishiura, S.; Hachiya, I. Heterocycles
006, 70, 57.
Hz, 1 H), 7.30–7.70 (m, 9 H), 7.90 (d, J = 7.3 Hz, 2 H), 8.10 (d, J = 7.2 Hz,
(
2
H).
2
13
C NMR (100 MHz, CDCl ): δ = 74.3, 87.4, 125.6, 127.5, 128.8, 129.2,
(18) Reynolds, S. C.; Wengryniuk, S. E.; Hartel, A. M. Tetrahedron Lett.
2007, 48, 6751.
3
129.3, 129.4, 129.5, 130.7, 134.4, 134.6, 138.7, 141.1, 163.3, 194.6.
(
19) Larraufie, M.-H.; Pellet, R.; Fensterbank, L.; Goddard, J.-P.;
Anal. Calcd for C22H15Cl NO : C, 66.68; H, 3.82; N, 3.53. Found: C,
2
2
Lacote, E.; Malacria, M.; Ollivier, C. Angew. Chem. Int. Ed. 2011,
66.61; H, 3.79; N, 3.74.
50, 4463.
(
20) Samimi, H. A.; Mamaghani, M.; Tabatabaeian, K. J. Heterocycl.
Chem. 2008, 45, 1765.
(
E)-1,3-Bis(4-chlorophenyl)prop-2-en-1-one (3a)
Yellow crystals; mp 156–158 °C.
IR (KBr): 3041, 1655, 1597, 883, 774, 699, 682 cm–1
(21) Mamaghani, M.; Tabatabaeian, K.; Samimi, H. A. Z. Kristallogr. -
New Cryst. Struct. 2008, 223, 390.
.
1
(22) Samimi, H. A.; Shams, Z. J. Iran. Chem. Soc. 2014, 11, 979.
H NMR (400 MHz, CDCl ): δ = 7.50 (m, 2 H), 7.53 (dd, J = 7.6, 1.8 Hz, 1
3
(23) Samimi, H. A.; Mohammadi, S. Synlett 2013, 24, 223.
(24) Samimi, H. A.; Mohammadi, S. J. Iran. Chem. Soc. 2014, 11, 69.
(25) Samimi, H. A.; Kiyani, H.; Shams, Z. J. Chem. Res. 2013, 37, 282.
(26) Samimi, H. A.; Yamin, B. M.; Hiedari, Z.; Narimani, L.
J. Heterocycl. Chem. accepted for publication.
H), 7.60 (m, 2 H), 7.73 (m, 2 H), 7.76 (d, J = 15.5 Hz, 1 H), 8.20 (dd, J =
7
.5, 2.2 Hz, 2 H).
13
C NMR (100 MHz, CDCl ): δ = 122.2, 128.4, 128.5, 129.3, 129.4,
3
1
32.3, 133.9, 136.8, 139.1, 144.1, 189.8.
Anal. Calcd for C15H10Cl O: C, 65.01; H, 3.64. Found: C, 65.08; H, 3.69.
(27) Samimi, H. A.; Yamin, B. M. J. Chem. Res. 2014, 38, 358.
2
(
(
28) Tomasini, C.; Vecchione, A. Org. Lett. 1999, 1, 2153.
29) Kump, J. E. G. In Comprehensive Organic Synthesis; Trost, B. M.;
Fleming, I., Eds.; Pergamon Press: Oxford, 1991, 469.
30) Sabitha, G.; Babu, R. S.; Rajkumar, M.; Reddy, C. S.; Yadav, J. S.
Tetrahedron Lett. 2001, 42, 3955.
Acknowledgment
(
We are thankful to the Research Council of Shahrekord University for
supporting this work, and to the Universiti Kebangsaan Malaysia In-
strumentation Center (UKM-DIP 2012-11) for the X-ray analysis.
(31) Saha, B.; Nandy, J. P.; Shukla, S.; Siddiqui, I.; Iqbal, J. J. Org. Chem.
2002, 67, 7858.
(
(
32) Lucarini, S.; Tomasini, C. J. Org. Chem. 2001, 66, 727.
33) Cardillo, G.; Gentilucci, L.; Gianotti, M.; Tolomelli, A. Synlett
2000, 1309.
Supporting Information
(
(
34) Quinze, K.; Laurent, A.; Mison, P. J. Fluorine Chem. 1989, 44, 233.
35) Sheldrick, G. M. SADABS A Program for Structure Determination;
University of Göttingen: Germany, 1996.
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0034-1379029.
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Georg Thieme Verlag Stuttgart · New York — Synthesis 2015, 47, 129–133
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