SYNTHESIS OF ENANTIOMERIC (+)- AND (–)-6-(1-METHYLETHYLIDENE)-...
813
ppm: 1.56 d (3H, 1″-Me, 3J = 6.6 Hz), 1.67 d (1H, OH,
3J = 7.0 Hz), 1.81 s and 1.85 s (3H each, Me), 4.04 d.d
Data Centre (entry no. CCDC 893073) and are avail-
3
3
(1H, 1-H, J1,32 = 3.0, J1,5 = 6.0 Hz), 4.96 d.d (1H, 5-H,
(3aS,6aS)-3,3-Dichloro-6-(propan-2-ylidene)-
3,3a,6,6a-tetrahydro-2H-cyclopenta[b]furan-2-one
(XI). Amide IX, 0.26 g (0.77 mmol), was dissolved in
5 mL of dioxane, 7.8 mL of 0.5 N H2SO4 was added
dropwise under stirring, and the mixture was heated
for 1 h under reflux with stirring. When the reaction
was complete, the mixture was diluted with chloro-
form, washed with a saturated solution of sodium
hydrogen carbonate to pH 5, and the product was
extracted into CHCl3 (3×50 mL). The combined ex-
tracts were washed with brine, dried over Na2SO4, and
concentrated, and the residue was subjected to silica
gel column chromatography using petroleum ether–
ethyl acetate (20:1) as eluent. Yield 0.15 g (87%),
colorless crystals, mp 68°C, Rf 0.66 (petroleum ether–
ethyl acetate, 7:3), [α]D20 = –55° (c = 1.0, CHCl3).
3J5,1 = 6.0, J5,OH = 7.0 Hz), 5.08 d.q (1H, 1″-H,
3
3
3J1″,Me = 6.6, J1″,NH = 7.0 Hz), 6.07 d (1H, 3-H, J3,2
=
3
3
5.9 Hz), 6.54 d.d (1H, 2-H, J2,1 = 3.0, J2,3 = 5.9 Hz),
7.03 d (1H, NH, JNH,1″ = 7.0 Hz), 7.27–7.37 m (5H,
3
Ph). 13C NMR spectrum, δC, ppm: 21.00 (Me), 21.30
(1″-Me), 50.04 (C1″), 61.00 (C1), 76.65 (C5), 86.65
(C1'), 126.03 (Cm), 127.59 (Cp), 128.80 (Co), 130.18
(CMe2), 130.26 (C3), 131.89 (C2), 140.51 (C4), 142.19
(Ci), 165.80 (C2′). Found, %: C 61.12; H 5.99;
Cl 20.11; N 3.99. C18H21Cl2NO2. Calculated, %:
C 61.02; H 5.97; Cl 20.01; N 3.95.
2,2-Dichloro-2-[(1S,5S)-5-hydroxy-4-(propan-
2-ylidene)cyclopent-2-en-1-yl]-N-[(1R)-1-phenyl-
ethyl]acetamide (X). Colorless crystals, mp 104°C,
Rf 0.30 (petroleum ether–ethyl acetate, 8:2), [α]D20
=
1H NMR spectrum, δ, ppm: 1.85 s and 1.95 s (3H each,
+232° (c = 1.0, CHCl3). IR spectrum, ν, cm–1: 3458
3
1
Me), 4.11 br.s (1H, 3a-H), 5.61 d (1H, 6a-H, J3a,6a
=
(OH), 3415 (NH), 1693 (C=O), 1552 (C=C). H NMR
3
3
5.2 Hz), 5.86 d (1H, 5-H, J5,4 = 5.8 Hz), 6.53 d (1H,
spectrum, δ, ppm: 1.56 d (3H, 1″-Me, J = 6.6 Hz),
4-H, J4,5 = 5.8 Hz). 13C NMR spectrum, δC, ppm:
3
3
1.70 d (1H, OH, J = 8.5 Hz), 1.81 s and 1.82 s (3H
21.36 and 21.44 (Me), 61.48 (C3a), 79.73 (C3), 79.86
(C6a), 127.68 (C5), 133.74 (C4), 134.78 (C1′), 136.35
(C6), 167.83 (C1). Found, %: C 51.59; H 4.33;
Cl 30.29. C10H10Cl2O2. Calculated, %: C 51.53;
H 4.32; Cl 30.42.
3
3
each, Me), 4.03 d.d (1H, 1-H, J1,2 = 2.5, J1,5
=
3
3
6.0 Hz), 4.92 d.d (1H, 5-H, J5,1 = 6.0, JOH,5 = 8.5 Hz),
5.13 d.q (1H, 1″-H, J1″,Me = 6.6, J1″,NH = 7.0 Hz),
3
3
3
6.08 d (1H, 3-H, J3,2 = 5.9 Hz), 6.54 d.d (1H, 2-H,
3J2,1 = 2.5, J2,3 = 5.9, Hz), 7.06 d (1H, NH, JNH,1″
=
3
3
7.0 Hz), 7.27–7.37 m (5H, Ph). 13C NMR spectrum, δC,
ppm: 20.27 (1″-Me), 20.70 and 21.27 (Me), 49.96
(C1″), 67.00 (C1), 71.57 (C5), 86.03 (C1′), 126.03 (Cm),
126.28 (C3), 127.59 (Cp), 128.72 (C2), 128.77 (Co),
130.08 (CMe2), 140.39 (C4), 142.10 (Ci), 167.35 (C2′).
Found, %: C 61.13, H 5.91; Cl 20.00; N 3.91.
C18H21Cl2NO2. Calculated, %: C 61.02; H 5.97;
Cl 20.01; N 3.95.
(3aR,6aR)-3,3-Dichloro-6-(propan-2-ylidene)-
3,3a,6,6a-tetraydro-2H-cyclopenta[b]furan-2-one
(XII) was synthesized in a similar way from 0.26 g
(0.77 mmol) of amide X. Yield 0.15 g (87%), colorless
crystals, mp 76°C, Rf 0.66 (petroleum ether–ethyl
acetate, 7:3), [α]D20 = +173° (c = 1.0, CHCl3). H NMR
1
spectrum, δ, ppm: 1.85 s and 1.95 s (3H each, Me),
3
4.11 br.s (1H, 3a-H), 5.61 d (1H, 6a-H, J6a,3a
=
3
5.2 Hz), 5.86 d (1H, 5-H, J5,4 = 5.8 Hz), 6.53 d (1H,
X-Ray diffraction data for compound (+)-X.
Colorless crystals. C18H21Cl2NO2. M 354.26. Ortho-
rhombic crystal system, space group P212121; unit cell
parameters (100 K): a = 5.6722(3), b = 15.0425(8), c =
4-H, J4,3 = 5.8 Hz). 13C NMR spectrum, δC, ppm:
3
21.36 and 21.44 (Me), 61.48 (C3a), 79.73 (C3), 79.86
(C6a), 127.68 (C5), 133.74 (C4), 134.78 (C1′), 136.35
(C6), 167.83 (C1). Found, %: C 51.61; H 4.36;
Cl 30.45. C10H10Cl2O2. Calculated, %: C 51.53;
H 4.32; Cl 30.42.
20.5905(11) Å; V = 1756.9(2) Å3; Z = 4; dcalc
=
1.339 g/cm3; μ = 0.378 mm–1. Total of 21563 reflec-
tion intensities were measured on a Bruker Smart Apex
II CCD diffractometer. The structure was solved by the
direct method and was refined by the full-matrix least-
squares procedure in anisotropic approximation from
6120 independent reflections (Rint = 0.0320). The final
divergence factors were wR2 = 0.0707 (against F2hkl for
all independent reflections) and R1 = 0.0296 [against
(3aS,6aS)-6-(Propan-2-ylidene)-3,3a,6,6a-tetra-
hydro-2H-cyclopenta[b]furan-2-one (I). Ammonium
chloride, 0.01 g (0.19 mmol), and zinc–copper couple,
0.25 g (4 mmol), were added under stirring in an argon
atmosphere to a solution of 0.15 g (0.64 mmol) of
compound XI in 15 mL of anhydrous methanol. The
mixture was stirred for 2 h on heating under reflux
(TLC), the precipitate was filtered off, the filtrate was
concentrated, the residue was dissolved in 20 mL of
F
hkl for 5732 reflections with I > 2σ(I)]; goodness of fit
1.032. The crystallographic data for compound (+)-X
were deposited to the Cambridge Crystallographic
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 50 No. 6 2014