10.1002/ejoc.201800077
European Journal of Organic Chemistry
FULL PAPER
54.53; H, 5.28; S, 11.20%); νmax/cm−1 (KBr): 2956, 2939 (CH) 1735 (CO),
1512 (C=C, Ar), 1317, 1114 (SO2) 840; 1H NMR (CDCl3, 300 MHz) δ
(ppm) = 1.84 [dq, J = 13.6 Hz, 3.2 Hz, 1H, one of C(4)H2], 2.10–2.36 [m,
2H, C(5)H2], 2.58 [qd, J = 13.2 Hz, 3.9 Hz, 1H, one of C(4)H2], 3.05 [dq, J
= 14.1 Hz, 3.4 Hz, 1H, one of C(6)H2], 3.56 (s, 3H, OCH3), 3.61–3.73 [m,
2H, one of C(6)H2 and C(3)H], 3.96 [dd, J = 4.5 Hz, 2.9 Hz, 1H, C(2)H],
6.95–7.07 (m, 2H, ArH), 7.12–7.23 (m, 2H, ArH); 13C NMR (CDCl3, 75.5
MHz) δ (ppm) = 22.9, 23.8 [2 × CH2, C(4)H2, C(5)H2], 43.8 [CH, C(3)H],
47.8 [CH2, C(6)H2], 52.7 (CH3, OCH3), 70.4 [CH, C(2)H], 115.8 [2 × ArCH,
d, 2JCF 21.4, C(3ʹ)H, C(5ʹ)H], 128.6 [2 × ArCH, d, 3JCF 8.1, C(2ʹ)H, C(6ʹ)H],
reported for trans 5n. νmax/cm−1 (film): 1741 (CO), 1317, 1282, 1251,
1213, 1180 (SO2), 761 (CS); 1H NMR (CDCl3, 300 MHz) δ (ppm) = 1.37 (t,
J = 7.1 Hz, 3H, OCH2CH3), 1.55 [d, J = 6.70 Hz, 3H, C(1ʹ)H3], 3.93–4.08
[m, 2H, C(2)H and C(3)H], 4.17–4.47 (sym m, 2H, OCH2CH3), 7.39–7.57
(overlapping dd and ddd, appears as m, 2H, ArH × 2), 7.64 (ddd, J = 7.6
Hz, 7.6 Hz, 1.1 Hz, 1H, ArH), 7.71 (d, J = 7.9 Hz, 1H, ArH); 13C NMR
(CDCl3, 75.5 MHz) δ (ppm) = 14.1 (CH3, OCH2CH3), 18.7 [CH3, C(1ʹ)H3],
35.7 [CH, C(3)H], 62.9 (CH2, OCH2CH3), 72.3 [CH, C(2)H], 121.6 (CH,
aromatic CH), 125.4 (CH, aromatic CH), 129.0 (CH, aromatic CH), 134.1
(CH, aromatic CH), 137.4 (C, aromatic C), 140.3 (C, aromatic C), 164.0
(C, CO); HRMS (ESI+): Exact mass calculated for C12H15O4S [M+H]+,
255.0691. Found 255.0688. m/z (ESI+): 255.2 [M+H]+.
4
1
135.3 [C, d, JCF 3.3, C(1ʹ)], 162.1 [C, JCF 246.9, C(4ʹ)], 166.4 (C, CO);
HRMS (ESI+): Exact mass calculated for C13H16O4FS [M+H]+, 287.0753.
Found 287.0767. m/z (ESI+): 287.1 [M+H]+.
The following signals appear in 1H NMR spectra of the crude product and
are tentatively assigned to cis 6n; 1H NMR (CDCl3, 400 MHz) δ (ppm) =
1.26 (t, J = 7.1 Hz, 3H, OCH2CH3), 1.55 [d, J = 7.1 Hz, 3H, C(1ʹ)H3], 3.92
[quint, J = 6.8 Hz, 1H, C(3)H], 4.16–4.32 (m, 2H, OCH2CH3), 4.38 [d, J =
6.6 Hz, 1H, C(2)H] 7.40–7.54 (m, 2H, ArH), 7.59–7.66 (m, 1H, ArH), 7.71
(d, J = 7.1 Hz, 1H, ArH).
Methyl isothiochroman-1-carboxylate 2,2-dioxide
7
The title
compound was prepared according to general procedure C, using methyl
2-diazo-2-(phenethylsulfinyl)acetate 1m ( 80 mg, 0.30 mmol), CuCl2 (2.0
mg, 15 μmol), NaBARF (15.7 mg, 18 μmol) and bis(oxazoline) ligand
(4R,5S)-diPh (8.2 mg, 18 μmol) in dichloromethane (20 mL), stirred while
heating under reflux for
2
h. Following purification by column
[(2R,3R)-3-Methyl-1,1-dioxido-2,3-dihydrobenzo[b]thiophen-2-
chromatography on silica gel, using ethyl acetate-hexane (10:90) as
eluent, methyl isothiochroman-1-carboxylate 2,2-dioxide 7 (49 mg, 68%)
was isolated as a white solid; mp 118–119 °C; 0% ee (determined by
chiral HPLC); νmax/cm−1 (KBr): 2936 (CH), 1736 (CO), 1429 (C=C, ArH),
1321, 1312, 1298, 1121 (SO2), 740 (CS); 1H NMR (CDCl3, 600 MHz) δ
(ppm) = 3.22 (dddd, J = 14.1 Hz, 5.1 Hz, 3.8 Hz, 2.6 Hz, 1H, one of
SO2CH2), 3.43–3.59 (m, 2H, SO2CH2CH2), 3.84 (s, 3H, OCH3), 3.93–
4.01 (ddd, J = 14.1 Hz, 11.4 Hz, 5.7 Hz, 1H, one of SO2CH2), 4.99 (d, J =
2.5, 1H, SO2CH), 7.11–7.14 (m, 1H, ArH), 7.24–7.29 (m, 2H, ArH), 7.31–
7.36 (m, 1H, ArH); 13C NMR (CDCl3, 150.9 MHz) δ (ppm) = 29.0 (CH2,
SO2CH2CH2), 45.9 (CH2, SO2CH2), 53.8 (CH3, OCH3), 67.8 (CH, SO2CH),
127.4 (CH, aromatic CH), 128.1 (C, aromatic C), 129.3 (CH, aromatic
CH), 130.0 (CH, aromatic CH), 130.1 (CH, aromatic CH), 132.0 (C,
aromatic, C), 166.5 (C, CO); HRMS (ESI+): Exact mass calculated for
yl](phenyl)methanone 5o The title compound was prepared according
general procedure C, using 2-diazo-2-(2-ethylphenyl)sulfonyl-1-
phenylethanone 1o (100 mg, 0.32 mmol), CuCl2 (2.2 mg, 16 μmol),
NaBARF (16.9 mg, 19 μmol) and bis(oxazoline) ligand (4R)-Ph (6.4
mg,19 μmol) in dichloromethane (25 mL), stirred while heating under
reflux for 5 h. 1H NMR spectroscopy of the crude product showed that the
reaction was approx 65% efficient (9% cis 6o: 91% trans 5o). Following
purification by column chromatography on silica gel, using ethyl acetate-
hexane
(10:90)
as
eluent,
[(2R,3R)-3-methyl-1,1-dioxido-2,3-
dihydrobenzo[b]thiophen-2-yl](phenyl)methanone (1% cis 6o, 99% trans
5o) (34 mg, 38%) was isolated as a colourless oil; 71% ee (trans 5o)
(determined by chiral HPLC); νmax/cm−1 (film): 2922, 2851 (CH), 1684
(CO), 1597 (C=C, Ar), 1309, 1156 (SO2), 751 (CS); 1H NMR (CDCl3, 400
MHz) δ (ppm) = 1.54 [d, J = 7.0 Hz, 3H, C(1ʹ)H3], 4.41 [quint, J = 6.9 Hz,
1H, C(3)H], 5.02 [d, J = 6.9 Hz, 1H, C(2)H], 7.46–7.60 (m, 4H, ArH),
7.63–7.72 (m, 3H, ArH), 8.19–8.22 (m, 2H, ArH); 13C NMR (CDCl3, 75.5
MHz) δ (ppm) = 18.8 [CH3, C(1ʹ)H3], 35.7 [CH, C(3)H], 73.8 [CH, C(2)H],
121.6 (CH, aromatic CH), 125.4, 129.1, 129.5, 134.2, 134.6 (CH,
aromatic CH), 136.3 (C, aromatic C), 137.3 (C, aromatic C), 141.2 (C,
aromatic C), 188.2 (C, CO); HRMS (ESI+): Exact mass calculated for
C16H15O3S [M+H]+, 287.0742. Found 287.0732. m/z (ESI+): 287.1 [M+H]+.
The following signals appear in 1H NMR spectra of the crude product and
are tentatively assigned to cis 6o: 1H NMR (CDCl3, 400 MHz) δ (ppm) =
1.81 [d, J = 6.3 Hz, 3H, C(1ʹ)H3], 4.09 [quint, J = 6.4 Hz, 1H, C(3)H], 5.45
[d, J = 5.4 Hz, 1H, C(2)H].
C
11H13O4S [M+H] +, 241.0535. Found 241.0527. m/z (ESI+): 241.1
[M+H]+.
(2R,3R) Ethyl 3-methyl-2, 3-dihydrobenzo[b]thiophene-2-carboxylate
1, 1-dioxide 5n The title compound was prepared according to general
procedure C, using ethyl 2-diazo-2-(2-ethylphenyl)sulfonylacetate 1n
(150 mg, 0.53 mmol), CuCl2 (3.53 mg, 26.6 μmol), NaBARF (28mg, 31.9
μmol) and bis(oxazoline) ligand (4R)-Ph (10.6 mg, 31.9 μmol) in
dichloromethane (20 mL), stirred while heating under reflux for 2 h. 1H
NMR spectroscopy of the crude product showed that the reaction was
approx 90% efficient (89% cis 6n: 11% trans 5n). Following purification
by column chromatography on silica gel, using ethyl acetate-hexane
(10:90) as eluent, (2R,3R) ethyl 3-methyl-2, 3-dihydrobenzo[b]thiophene-
2-carboxylate 1,1-dioxide (6% cis 6n, 94% trans 5n) (130 mg, 91%) was
isolated as a colourless oil (cis 6n -82% ee, trans 5n -80% ee);
(determined by chiral-HPLC); The following spectral characteristics are
1-(3-Methyl-1,1-dioxido-2,3-dihydrobenzo[b]thiophen-2-yl)ethanone
cis 5p The title compound was prepared according to general procedure
C, using 1-diazo-1-(2-ethylphenyl)sulfonylpropan-2-one 1p (80 mg, 0.32
mmol), CuCl2 (2.1 mg, 16 μmol), NaBARF (16.8 mg, 19 μmol) and
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