BAYGUZINA et al.
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The mass spectra were recorded on a Shimadzu
GCMS-QP2010 Plus instrument (SPB-5 capillary
column, 30 m×0.25 mm; carrier gas helium; oven tem-
perature programming from 40 to 300°C at a rate of
8 deg/min; injector temperature 280°C, ion source
temperature 200°C; electron impact, 70 eV). Chro-
matographic analyses were obtained with Shimadzu
GC-9A and GC-2014 gas chromatographs (2 m×3-mm
column packed with 5% SE-30 on Chromaton N-AW-
HMDS; oven temperature programming from 50 to
270°C at a rate of 8 deg/min; carrier gas helium, flow
rate 47 mL/min). GC/MS analysis was also performed
on a Shimadzu GCMS-QP2010 Ultra instrument
(Supel-Q PLOT capillary column, 30 m×0.53 mm;
oven temperature programming from 37 to 250°C
at a rate of 10 deg/min; carrier gas helium, flow rate
3 mL/min; ion source temperature 200°C; electron
impact, 70 eV).
(C2, C5). Mass spectrum, m/z (Irel, %): 72 (29) [M]+, 71
(27), 43 (22), 42 (100), 41 (52), 40 (13), 39 (25), 29
(22), 27 (33), 15 (10). Found, %: C 66.75; H 11.11.
C4H8O. Calculated, %: C 66.63; H 11.18.
1,4-Dioxane (2b). Yield 1.74 g (99%), colorless
1
liquid, bp 101°C [5]. H NMR spectrum: δ 3.69 ppm,
br.s (CH2). 13C NMR spectrum: δC 66.97 ppm. Mass
spectrum, m/z (Irel, %): 88 (31) [M]+, 58 (24), 57 (6),
43 (11), 31 (17), 30 (13), 29 (37), 28 (100), 26 (9), 15
(16). Found, %: C 54.41; H 9.29. C4H8O2. Calculated,
%: C 54.53; H 9.15.
Tetrahydro-2H-pyran (3b). Yield 1.70 g (99%),
1
colorless liquid, bp 88°C [5]. H NMR spectrum, δ,
ppm: 1.56 m (4H, 3-H, 5-H), 1.62 m (2H, 4-H), 3.64 t
(4H, 2-H, 6-H, J = 5 Hz). 13C NMR spectrum, δC, ppm:
23.41 (C4), 26.55 (C3, C5), 68.65 (C2, C6). Mass spec-
trum, m/z (Irel, %): 86 (50) [M]+, 85 (57), 56 (59), 55
(23), 45 (56), 41 (100), 39 (29), 29 (51), 28 (59), 27
(501). Found, %: C 69.81; H 11.81. C5H10O. Calculat-
ed, %: C 69.72; H 11.70.
Commercially available butane-1,4-diol, ethylene
glycol, pentan-1,5-diol, hexane-2,5-diol, diethylene
glycol, triethylene glycol, 2,2′-sulfanediyldiethanol,
hexane-1,6-diol, and heptane-1,7-diol were used;
liquid diols were distilled before use. The copper com-
pounds CuCl2·2H2O, CuBr2, CuBr, CuI, Cu(OAc)2,
Cu(acac)2, copper(II) benzoate, and copper(II)
salicylate were commercial reagents.
2,5-Dimethyltetrahydrofuran (4b). Yield 1.98 g
(99%), colorless liquid, bp 90–92°C [6], a 1:1 mixture
1
of cis and trans isomers. H NMR spectrum, δ, ppm:
trans isomer: 1.04 d (6H, CH3, J = 6.5 Hz), 1.27 m and
1.86 m (2H each, 3-H, 4-H), 3.93 m (2H, 2-H, 5-H);
cis isomer: 1.00 d (6H, CH3, J = 6.5 Hz), 1.27 m and
1.77 m (2H each, 3-H, 4-H), 3.73 m (2H, 2-H, 5-H).
13C NMR spectrum, δC, ppm: trans isomer: 21.17
(CH3), 32.86 (C3, C4), 75.04 (C2, C5); cis isomer: 21.17
(CH3), 33.99 (C3, C4), 74.17 (C2, C5). Mass spectrum,
m/z (Irel, %): 100 (10) [M]+, 85 (74), 67 (20), 57 (23),
56 (100), 45 (25), 43 (60), 41 (75), 29 (25), 27 (17).
Found, %: C 71.82; H 12.15. C6H12O. Calculated, %:
C 71.95; H 12.08.
General procedure for the synthesis of cyclic
ethers 1b–4b and 7b–9b. The reactions were carried
out in a 12-mL glass ampule which was placed in
a 17-mL stainless steel high-pressure microreactor.
An ampule was charged under argon with 0.2–2 mmol
(50–500 mg) of CuBr2 and 20 mmol of the correspond-
ing diol (1.8 g of 1a, 1.24 g of 2a, 2.08 g of 3a, 2.36 g
of 4a, 2.12 g of 5a, 3 g of 6a, 2.44 g of 7a, 2.36 g of
8a in 1 mL of THF, or 2.64 g of 9a). The ampule was
sealed and placed in the reactor, and the reactor was
tightly closed and heated for 3–12 h at 175–190°C
with continuous stirring. The reactor was cooled to
~20°C, the ampule was opened, the mixture was
neutralized with 10% aqueous sodium carbonate, and
the organic phase was extracted with methylene
chloride. The extract was filtered, the solvent was
distilled off, and the residue was distilled under
atmospheric or reduced pressure. For identification,
samples of 1b–4b and 7b–9b obtained in 3–6 runs
were combined.
1,4-Oxathiane (7b). Yield 2.06 g (99%), colorless
liquid, bp 71–72°C (60 mm); published data [7]:
bp 147°C. 1H NMR spectrum, δ, ppm: 2.62 t (4H, 3-H,
5-H, J = 5 Hz), 3.91 t (4H, 2-H, 6-H, J = 5 Hz).
13C NMR spectrum, δC, ppm: 27.07 (C2, C6), 68.79
(C3, C5). Mass spectrum, m/z (Irel, %): 104 (52) [M]+,
76 (7), 74 (18), 61 (45), 60 (11), 59 (10), 48 (7), 47
(11), 46 (100), 45 (25). Found, %: C 46.29; H 7.85.
C4H8OS. Calculated, %: C 46.12; H 7.74.
Oxepane (8b). Yield 1.98 g (99%), yellowish
1
liquid, bp 118–119°C [5]. H NMR spectrum, δ, ppm:
1.35 br.s (4H, 4-H, 5-H), 1.57–1.62 m (4H, 3-H, 6-H),
3.39 t (4H, 2-H, 7-H, J = 6 Hz). 13C NMR spectrum,
δC, ppm: 26.08 (C4, C5), 29.56 (C3, C6), 70.64 (C2, C7).
Mass spectrum, m/z (Irel, %): 100 (26) [M]+, 82 (4), 70
Tetrahydrofuran (1b). Yield 1.42 g (99%), color-
less liquid, bp 66°C [5]. H NMR spectrum, δ, ppm:
1
1.84 br.s (4H, 3-H, 4-H), 3.73 br.s (4H, 2-H, 5-H).
13C NMR spectrum, δC, ppm: 25.60 (C3, C4), 67.96
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 53 No. 12 2017