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STONČIUS ET AL.
(+)-(1R,5S,7E)-6. Purified by column chromatography on silica gel
with a petroleum ether-ethyl acetate mixture (95:5) to give (+)-6 as a
yellow oil (44%); [α]D = +77 (c = 0.53, CHCl3).
(CH2), 32.69 (CH2), 34.88 (CH), 75.49 (CH), 120.97 (CH), 126.02 (CH),
127.85 (CH), 128.76 (CH), 135.0 (C), 137.68 (C), 169.92 (C=O); IR: 2922,
1740, 1651, 1596, 1244, 1038, 698 cmÀ1; Anal. Calcd for C27H28O4: C,
77.86; H, 6.78. Found: C, 77.93; H, 6.86.
(3’E,7’E)-3’,7’-di(benzylidene)dispiro[[1,3]dioxolane-2,2’-bicyclo
[3.3.1]nonane-6’,2”-[1,3]dioxolane] 7. Ethylene glycol (280 μL,
5 mmol) and p-toluenesulfonic acid monohydrate (11 mg, 0.1 mmol) were
added to a solution of 2 (82 mg, 0.25 mmol) in dry benzene (10 mL) and
the resulting mixture was heated under reflux with Dean-Stark trap for
24 h, then cooled and evaporated to dryness. The residue was dissolved in di-
chloromethane (20 mL), washed with saturated aqueous solution of NaHCO3
(2 × 5 mL) and water (5 mL). The organic phase was dried (Na2SO4), filtered,
and evaporated. The residue was purified by column chromatography on sil-
ica gel with a petroleum ether-ethyl acetate mixture (9:1, Rf = 0.32), followed
by recrystallization from ethyl acetate to give ( )-7 as a colorless solid
(87 mg, 84%); mp 181À183 °C; 1H NMR: δ 2.02À2.07 (m, 2H), 2.31À2.35
(m, 2H), 2.38 (ddd, J = 15.3, 5.2, 2.8 Hz, 2H), 3.17 (d, J = 15.3 Hz, 2H),
3.81À4.08 (m, 8H), 6.52 (d, J = 2.8 Hz, 2H), 7.17À7.35 (m, 10H); 13C NMR:
δ 28.31 (CH2), 29.88 (CH2), 40.04 (CH), 63.07 (CH2), 66.04 (CH2), 109.79
(C), 124.03 (CH), 126.16 (CH), 127.95 (CH), 129.18 (CH), 136.25 (C),
137.43 (C); IR: 2910, 2881, 1599, 1107, 1031, 913, 698 cmÀ1; Anal. Calcd for
C27H28O4: C, 77.86; H, 6.78. Found: C, 77.97; H, 6.77.
(À)-(1R,2S,3E,5R,6S,7E)-9. Purified by column chromatography on
silica gel with a petroleum ether-ethyl acetate mixture (85:15) to afford
(À)-9 as a colorless solid (93%); mp 143À145 °C; [α]D = À467 (c = 1.0,
CHCl3); CD (EtOH): λmax (Δε/dm3 molÀ1 cmÀ1) 263 (À103.1), 248 (0),
235 (+90.2); UV (EtOH): λmax (lgε) 242 (4.3).
(5E,8E)-5,8-dibenzylidenetricyclo[4.3.0.03,7]nonane-6,7-diol 10. 6M
aqueous HCl (2 mL) was added to a solution of 2 (66 mg, 0.2 mmol) in
DCM (4 mL), followed by zinc dust (131 mg, 2 mmol) and the reaction
mixture was stirred at room temperature. An additional amount of Zn dust
(262 mg, 4 mmol) was added to the reaction mixture in two portions at 1-h
intervals. After stirring overnight at room temperature, the reaction mix-
ture was diluted with ethyl acetate (20 mL) and filtered through a pad of
Celite. The filtrate was washed with water (2 × 10 mL), saturated aqueous
solution of NaHCO3 (2 × 10 mL), brine (10 mL), dried, and evaporated.
The residue was recrystallized from ethyl acetate to afford ( )-10 as a
colorless solid (34 mg, 52%); mp 228À230 °C; 1H NMR (DMSO-d6): δ 1.30
(br s, 2H), 1.88À1.94 (m, 2H), 2.42 (d, J = 15.3 Hz, 2H), 3.08 (d, J = 15.3 Hz,
2H), 5.02 (s, 2H), 6.52 (br s, 2H), 7.17À7.21 (m, 2H), 7.33À7.41 (m, 8H);
13C NMR (DMSO-d6): δ 33.11 (CH2), 38.78 (CH2), 40.88 (CH), 91.22 (C),
121.51 (CH), 125.99 (CH), 127.65 (CH), 128.52 (CH), 137.87 (C), 145.56
(C); IR: 3516, 3457, 2967, 1660, 1596, 1170, 1127, 1086, 1034, 918, 763,
693 cmÀ1; Anal. Calcd for C23H22O2: C, 83.60; H, 6.71. Found: C, 83.29; H, 6.73.
(À)-(1’R,3’E,5’R,7’E)-7. Purified by column chromatography on
silica gel with a petroleum ether-ethyl acetate mixture (9:1), followed by
recrystallization from dichloromethane-hexane to give (À)-7 as a color-
less solid (87%); mp 190-192 °C; [α]D = À440 (c = 1.0, CHCl3); CD
(DCM): λmax (Δε/dm3 molÀ1 cmÀ1) 266 (À115.3), 253 (0), 241 (+141.3);
UV (DCM): λmax (lgε) 245 (4.5).
(À)-(1R,3R,5E,6R,7R,8E)-10. Purified by recrystallization from
ethyl acetate to give (À)-10 as a colorless solid (39%); mp 216À218 °C;
[α]D = À313 (c = 0.27, MeOH).
Endo,endo-(3E,7E)-3,7-dibenzylidenebicyclo[3.3.1]nonane-2,6-diol
833
. Sodium borohydride (151 mg, 4 mmol) was suspended in dry acetoni-
(5E,8E)-7-(acetyloxy)-5,8-dibenzylidenetricyclo[4.3.0.03,7]non-6-yl
acetate 11. The reduction of 2 (0.2 mmol scale) was carried out as
described above and the crude diol 10 was then treated with acetic anhy-
dride (190 μL, 2 mmol) and DMAP (5 mg, 0.04 mmol) in dry pyridine
(2 mL) overnight at 80 °C. The cooled reaction mixture was diluted with
ethyl acetate (10 mL) and successively washed with water (10 mL), 10%
aqueous solution of HCl (2 × 10 mL), and saturated aqueous solution of
NaHCO3 (10 mL), dried, and evaporated. The residue was purified by col-
umn chromatography on silica gel with a petroleum ether-ethyl acetate
mixture (95:5, Rf = 0.22), followed by recrystallization from ethyl acetate-
hexane to afford 11 as a colorless solid (31 mg, 37%); mp 192À193 °C; 1H
NMR: δ 1.61 (br s, 2H), 2.21 (s, 6H), 2.58 (dd, J= 15.4, 1.1 Hz, 2H), 2.91 (d,
J = 15.4 Hz, 2H), 3.18 (br s, 2H), 6.48 (br s, 2H), 7.20À7.26 (m, 2H), 7.31À7.40
(m, 8H); 13C NMR: δ 21.75 (CH3), 33.52 (CH2), 37.95 (CH), 38.64 (CH2),
97.70 (C), 124.97 (CH), 126.77 (CH), 128.33 (2 × CH), 136.96 (C), 137.17 (C),
170.39 (C=O); IR: 2951, 1741, 1668, 1598, 1368, 1242, 1217, 1091, 760,
696 cmÀ1; Anal. Calcd for C27H26O4: C, 78.24; H, 6.32. Found: C, 78.16; H, 6.30.
trile (4 mL) under Ar and the suspension was cooled to À12 °C. A solution of
2 (164 mg, 0.5 mmol) in dry DCM (4 mL) was added dropwise to the stirred
suspension, followed by a slow addition of cooled to 0 °C trifluoroacetic acid
(2.3 mL, 31 mmol). The resulting mixture was allowed to reach room
temperature over 2 h, and then carefully neutralized by an addition of 10%
aqueous NaOH solution. The organic phase was separated and the aqueous
phase was extracted with DCM (3 × 10 mL). The combined organic phase
was washed with 5% aqueous NaOH solution (10 mL), water (10 mL), dried
(Na2SO4), filtered, and evaporated. The residue was purified by column chro-
matography on silica gel with a petroleum ether-ethyl acetate mixture (75:25,
Rf = 0.28) to give ( )-8 as a colorless solid (154 mg, 93%); mp 175À177 °C
(reported33 mp 175À179 °C); 1H NMR: δ 1.61 (s, 1H), 1.64 (s, 1H), 1.98-
2.08 (m, 4H), 2.18-2.24 (m, 2H), 3.26 (d, J = 15.8 Hz, 2H), 4.37 (br s, 2H),
6.47 (br s, 2H), 7.17À7.36 (m, 10H); 13C NMR (75 MHz, CDCl3): 27.19
(CH2), 33.20 (CH2), 37.98 (CH), 74.58 (CH), 120.17 (CH), 126.03 (CH),
128.15 (CH), 128.87 (CH), 137.78 (C), 140.24 (C), in agreement with the
literature data.33
(À)-(1R,2S,3E,5R,6S,7E)-8. Purified by column chromatography on
silica gel with a petroleum ether-ethyl acetate mixture (75:25) to afford
(À)-8 as a colorless solid (90%); mp 185À187 °C; [α]D = À562 (c = 1.0,
CHCl3); CD (EtOH): λmax (Δε/dm3 molÀ1 cmÀ1) 266 (À80.8), 253 (0), 240
(+83.4); UV (EtOH): λmax (lgε) 245 (4.3). Crystals suitable for X-ray
diffraction were obtained by vapor diffusion of petroleum ether to the
solution of (À)-8 in diethyl ether.
(À)-(1R,3R,5E,6R,7R,8E)-11. Purified by column chromatography on
silica gel with a petroleum ether-ethyl acetate mixture (95:5, Rf = 0.22),
followed by recrystallization from hexane to give (À)-11 as a colorless solid
(36%); mp 165À166 °C; [α]D = À400 (c = 0.5, CHCl3); CD (EtOH): λmax (Δε/
dm3 molÀ1 cmÀ1) 264 (À49.4), 235 (0), 220 (+7.9); UV (EtOH): λmax (lgε)
264 (4.7).
O,O’-(3E,7E)-3,7-dibenzylidenebicyclo[3.3.1]nonane-2,6-diyl S,S’-
dimethyl dicarbonodithioate 12. Sodium hydride (80 mg, 60% disper-
sion in mineral oil, 2 mmol) was washed with dry hexane (3 × 2 mL) and
dried by flushing with dry Ar. The resulting powder was suspended in dry
THF (2 mL) and cooled to 0 °C. A solution of diol 8 (67 mg, 0.2 mmol) in
dry THF (3 mL) was added dropwise and the mixture was stirred for
30 min at room temperature. Freshly distilled CS2 (96 μL, 1.6 mmol) was
added dropwise and the mixture was stirred for another 30 min; methyl
iodide (99 μL, 1.6 mmol) was then added and stirring was continued for
another 4 h at room temperature. The reaction mixture was quenched by
an addition of saturated aqueous solution of NH4Cl (10 mL) and extracted
with ethyl acetate (2 × 10 mL). The combined organic phase was washed
with brine (10 mL), dried, and evaporated. The residue was purified by
Endo,endo-(3E,7E)-3,7-dibenzylidenebicyclo[3.3.1]nonane-2,6-diyl
diacetate 9. Acetic anhydride (190 μL, 2 mmol) was added to a solution of
8 (67 mg, 0.2 mmol) and DMAP (5 mg, 0.04 mmol) in dry pyridine (2 mL)
and the mixture was stirred under Ar for 2 h, then diluted with water
(10 mL) and extracted with dichloromethane (3 × 10 mL). The combined
organic phase was washed with 10% aqueous solution of HCl (2 × 10 mL)
and saturated aqueous solution of NaHCO3 (10 mL), dried, and evaporated.
The residue was purified by column chromatography on silica gel with a pe-
troleum ether-ethyl acetate mixture (85:15, Rf = 0.33) to afford ( )-9 as a col-
orless solid (70 mg, 84%); mp 152À154 °C; 1H NMR: δ 2.05À2.19 (m, 4H),
2.15 (s, 6H), 2.31À2.39 (m, 2H), 3.32 (d, J = 15.4 Hz, 2H), 5.60 (br s, 2H),
6.38 (br s, 2H), 7.23À7.40 (m, 10H); 13C NMR: δ 21.01 (CH3), 28.31
Chirality DOI 10.1002/chir