Cascade cyclization: An easy access to highly unsaturated polycyclic ring systems through a tandem stille/[4 + 2] reaction under mild conditions

Article abstract of DOI:10.1021/ol0264253

(matrix presented) The synthesis of several polycyclic compounds 1a-c, 2, and 3 has been performed through a tandem Stille/[4 + 2] cascade reaction from cyclic bis(enoltrifluomethanesulfonate) 4a-c, 5, and 6, respectively. The reaction proceeds very effic

Full text of DOI:10.1021/ol0264253

Cascade Cyclization: an Easy Access to Highly Unsaturated Polycyclic Ring Systems through a
Tandem Stille/[4+2] Reaction under Mild Conditions
Sébastien Brückner, Estelle Abraham, Philippe Klotz, Jean Suffert*
Laboratoire de Pharmacochimie de la Communication Cellulaire
(
UMR 7081 CNRS/ULP), Faculté de Pharmacie, 74 route du Rhin 67401 ILLKIRCH-Cedex,
France
Supporting Information
General Methods. Reactions were run under an atmosphere of argon in oven-dried glassware using a
standard syringe, cannula, and septa apparatus. Et O and THF were distilled from sodium
2
benzophenone. Benzene, CH Cl and DMF were distilled from CaH . Et N and i-Pr NH were distilled
2
2
2
3
2
from KOH. Crude products were purified by flash column chromatography on Merck 230-400 mesh
silica gel. For some compounds, 2 % Et N treated silica gel was used to avoid decomposition. Analytical
3
1
13
TLC was carried out on Merck (Kieselgel 60F-254) silica gel plates. H and C NMR spectra were
recorded at 200, 300 or 500 MHz using the residual solvent signal as internal reference (CDCl , 7.27 and
3
7
7 ppm ; C D , 7.16). Chemical shifts are quoted in ppm, coupling constants (J) are given in Hz. The
6
6
following abbreviations are used to describe peak patterns when appropriate: s (singlet), d (doublet), t
triplet), q (quartet), quint (quintet), m (multiplet), br (broad). Melting points were determined with a
(
glass capillary apparatus and are uncorrected. Mass spectra (MS) by Electronical Impact (EI) were
obtained from the Service de spectrométrie de Masse of the Chemistry Institut of Strasbourg (France)
and Mass Spectral Analysis by Electro-Spray were performed using a Mariner ESI-Tof instrument from
Applied Bio-System /Perking Elmer. Combustion analyses were carried out by the Service de
Microanalyse of the Chemistry Institut of Strasbourg (France). Infrared data were recorded on a Perkin-
Elmer 1600 series FTIR spectrophotometer. n-BuLi and t-BuLi were titrated using N-pivaloyl o-
toluidine following the Suffert's procedure1.
(1R*,2R*)-1-(2-bromophenyl)-4-(trimethylsilyl)but-3-yne-1,2-diol (10) and (1S*,2R*)-1-(2-
bromophenyl)-4-(trimethylsilyl)but-3-yne-1,2-diol (10 anti)
O
O
TMS
CHO
HO OH
Br
HO OH
Li
Br
+
THF, -78°C
TMS
TMS
Br
1
0
10 anti
1

A solution of n-butyllithium (8.6 mL, 13.2 mmol, 1.1 equiv, 1.54 M in hexane) was added to a dried
round-bottom flask containing 3-(1-methoxy-1-methyl-ethoxy)-prop-1-ynyl]-trimethylsilyl (2.64 g, 13.2
mmol, 1.1 equiv) in freshly distilled THF (10 mL) at -78 °C. The reaction was stirred 30 min at this
temperature and then cannulated to a solution of 2-bromobenzaldehyde (2.22 g, 12 mmol, 1 equiv) in
THF (20 mL) at -78 °C. The mixture was stirred for 2 h at -78 °C and then quenched by addition of
saturated aqueous NaHCO (10 mL) and water (30 mL). After extraction with Et O, the combined
3
2
organic layers were washed with water, brine, dried over MgSO and concentrated in vacuo. The crude
4
product was purified by silica gel flash column chromatography (ether/hexane 5/95) to give the
protected alcohols as an oil. The alcohols were deprotected by disolving this oil in methanol (30 mL)
containing PPTS (0.30 g, 1.2 mmol, 0.1 equiv). The solution was stirred for 30 min at r.t. and quenched
with the addition of brine (40 mL). The mixture was extracted with Et O and the combined extracts were
2
washed with water, brine and dried over Na SO . Silica gel flash column chromatography (ether/hexane
2
4
5
/95) afforded compound 10 (1.8 g, 5.7 mmol) and 10 anti (1.8 g, 5.7 mmol) as white solids for a global
yield of 96 %.
Data for 10:
1
TLC: R 0.23 (ether/hexane 4/6). mp: 78-80 °C. H NMR (300 MHz, CDCl ): δ -0.14 (s, 9H), 2.71 (s
f
3
br, 2H, OH), 4.55 (d, 1H, J = 5.3), 5.22 (d, 1H, J = 5.3), 7.18 (td, 1H, J = 7.5, 1.9), 7.35 (td, 1H, J = 7.5,
1
3
1
1
1
.9), 7.54 (s, 1H), 7.56 (s, 1H). C NMR (50 MHz, CDCl ): δ -0.38, 66.43, 75.34, 91.75, 102.58,
3
23.05, 127.44, 128.69, 129.46, 132.57, 138.29. IR (CCl ): ν 3401 (br, OH), 2962, 2177 (C≡C), 1654,
4
+
570, 1473, 1440, 1250, 1122, 1055, 846, 785. MS (EI, 70 eV): m/z (%) 296 (1) [M-OH] , 258 (13), 233
+
(
1) [M-Br] , 184 (20), 127 (56).
Data for 10 anti:
TLC: R 0.32 (ether/hexane 4/6). mp 107-109 °C. H NMR (200 MHz, CDCl ): δ 0.11 (s, 9H), 3.39 (s
1
f
3
br, 2H, OH), 4.71 (d, 1H, J = 3.2), 5.27 (d, 1H, J = 3.1), 7.16 (td, 1H, J = 7.6, 1.8), 7.33 (td, 1H, J = 7.6,
1
3
1
7
.2), 7.51 (dd, 1H, J = 7.9, 1.2), 7.67 (dd, 1H, J = 7.9, 1.8). C NMR (50 MHz, CDCl ): δ - 0.36, 65.86,
3
4.60, 92.69, 101.62, 122.12, 127.09, 129.07, 129.40, 132.20, 137.86.
[((4R*,5R*)-2,2-dimethyl-5-{2-[(E)-2-(tributylstannyl)ethenyl]phenyl}-1,3-dioxolan-4-
yl)ethynyl](trimethyl)silane (12) via {[(4R*,5R*)-5-(2-bromophenyl)-2,2-dimethyl-1,3-dioxolan-4-
yl]ethynyl}(trimethyl)silane (A)
SnBu3
O
O
O
TMS
OH OH
Br
O
O
Bu Sn
O
3
11
TMS
pTsOH, acetone
TMS
Pd(PPh ) , PhH, 80°C
3
4
Br
SnBu3
10
A
12
2

A solution of compound 10 (0.589 g, 1.88 mmol, 1 equiv), 2,2-dimethoxypropane (1.15 mL, d = 0.847,
.4 mmol, 5 equiv) and p-TsOH (0.036 g, 0.19 mmol, 0.1 equiv) in acetone (10 mL) was stirred at r.t.
9
for one hour. The mixture was when added to brine (20 mL) and extracted with Et O. The combined
2
organic extract was washed with water, brine and dried over Na SO . After evaporation of the solvents
2
4
in vacuo, the residue was purified by silica gel flash column chromatography (ether/hexane 5/95) to give
the protected diol A as a yellowish oil (0.66 g, 1.87 mmol, 99 %).
1
TLC: R 0.33 (ether/hexane 5/95). H NMR (200 MHz, CDCl ): δ 0.18 (s, 9H), 1.61 (s, 3H), 1.64 (s,
f
3
3
7
1
1
H), 4.43 (d, 1H, J = 7.1), 5.54 (d, 1H, J = 7.1), 7.19 (td, 1H, J = 7.6, 1.7), 7.36 (td, 1H, J = 7.6, 1.7),
1
3
.56 (m, 2H). C NMR (50 MHz, CDCl ): δ -0.41, 26.33, 26.89, 73.00, 81.46, 92.72, 101.40, 110.92,
3
23.05, 127.65, 127.97, 129.67, 132.94, 136.83. IR (film): ν 3069, 2987, 2960, 2899, 2177 (C≡C), 1570,
472, 1440, 1374, 1343, 1250, 1210, 1163, 1121, 1061, 843, 758. MS (EI, 70 eV): m/z (%) 338 (2) [M-
+
+
+
+
CH ] , 336 (2) [M-OH] , 280 (1) [M-TMS] , 274 (1) [M-Br] , 167 (100), 152 (39). Anal. Calcd for
3
C H BrO Si: C, 54.39; H, 5.99. Found: C, 54.47; H, 6.10.
16
21
2
A solution of the protected diol A (5.3 g, 15 mmol, 1 equiv), trans-1,2-bis(tributylstannyl)ethylene 11
(
(
(
11.2 g, 19.5 mmol, 1.3 equiv) and Pd(PPh ) (0.87 g, 0.7 mmol, 0.05 equiv) in dry degassed benzene
3
4
100 mL) was heated at reflux, under argon, for several hours until the reaction was completed
monitored by TLC). The solvent was then evaporated under reduced pressure and the crude residue was
purified by flash column chromatography (ether/hexane 1/99) using Et N pretreated (2 %) silica gel. The
3
title compound 12 was isolated as a yellowish oil (6.72 g, 11.4 mmol, 76 %).
1
TLC: R 0.45 (ether/hexane 5/95). H NMR (300 MHz, CDCl ): δ 0.16 (s, 9H), 0.93 (m, 15H), 1.36 (m,
f
3
6
1
9
1
2
H), 1.56 (m, 6H), 1.59 (s, 3H), 1.60 (s, 3H), 4.61 (d, 1H, J = 7.8), 5.35 (d, 1H, J = 7.8), 6.75 (d, 1H, J =
1
3
9.5), 7.28-7.36 (m, 2H), 7.39 (d, 1H, J = 19.5), 7.42-7.52 (m, 2H). C NMR (50 MHz, CDCl ): δ -0.30,
3
1
2
3
.71 ( J = 336), 13.71, 26.18, 26.99, 27.28 ( J = 52), 29.14 ( J = 21), 71.67, 72.56, 80.14, 92.42,
C-Sn
C-Sn
C-Sn
01.44, 110.37, 126.72, 127.54, 128.53, 132.60, 134.54, 139.80, 143.63. IR (CHCl ): ν 3065, 2958,
3
927, 2854, 2176 (C≡C), 1602, 1561, 1456, 1379, 1250, 1213, 1118, 1053, 845, 757. Anal. Calcd for
C H O SiSn: C, 61.12; H, 8.55. Found: C, 61.05; H, 8.32.
30
50
2
[((4R*,5R*)-5-{2-[(E)-2-bromoethenyl]phenyl}-2,2-dimethyl-1,3-dioxolan-4-
yl)ethynyl](trimethyl)silane (13)
O
O
O
TMS
Br2
O
TMS
CCl , -20°C
4
SnBu3
Br
12
13
3

To a cold (-20 °C) stirred solution of vinylstannane 12 (4.90 g, 8.31 mmol, 1 equiv) in CCl (50 mL) was
4
added dropwise (slowly) a solution of bromine (1M in CCl , 8.31 mL, 8.31 mmol, 1 equiv). The mixture
4
was stirred for 5 min, the solvent was then evaporated under reduced pressure and the crude product
purified by silica gel flash column chromatography (ether/hexane 1/99 to 3/97) to afford the vinyl
bromide 13 as a yellowish oil ( 3.14 g, 8.29 mmol, 100 %).
1
TLC: R 0.35 (ether/hexane 5/95). H NMR (200 MHz, CDCl ): δ 0.20 (s, 9H), 1.60 (s, 3H) 1.61 (s,
f
3
3
1
9
2
H), 4.40 (d, 1H, J = 7.6), 5.28 (d, 1H, J = 7.6), 6.65 (d, 1H, J = 13.7), 7.26-7.36 (m, 3H), 7.54 (d br,
1
3
H, J = 7.8), 7.68 (d, 1H, J = 13.7). C NMR (50 MHz, CDCl ): δ -0.29, 26.30, 26.79, 73.00, 79.93,
3
3.35, 100.92, 108.65, 110.65, 126.66, 126.80, 128.63, 128.65, 133.87, 134.98, 135.22. IR (CHCl ): ν
3
977, 2934, 2870, 2805, 2243 (C≡C), 1608, 1490, 1446, 1383, 1252, 1114, 910, 845, 734. MS (EI, 70
+
+
+
eV) (intensity): calc'd for (C H BrO Si ) 379; found: 379 (1) [M] , 363 (1) [M-CH ] , 306 (1) [M-
1
8
23
2
3
+
OH] , 240 (3), 167 (100), 152 (35). Anal. Calcd for C H BrO Si: C, 56.99; H, 6.11. Found: C, 57.12;
1
8
23
2
H, 6.17
[((4R*,5R*)-2,2-dimethyl-5-{2-[(1E,3E)-4-(tributylstannyl)buta-1,3-dienyl]phenyl}-1,3-dioxolan-4-
yl)ethynyl](trimethyl)silane (14)
Bu Sn
3
O
O
O
O
SnBu3
11
Pd(PPh ) , PhH, 80°C
TMS
3
4
TMS
Br
SnBu3
13
14
A solution of compound 13 (0.328 g, 0.865 mmol, 1 equiv), trans-1,2-bis(tributylstannyl)ethylene 11
(
(
0.681 g, 1.12 mmol, 1.3 equiv) and Pd(PPh ) (50 mg, 0.04 mmol, 0.05 equiv) in dry degassed benzene
3
4
15 mL) was heated at reflux, under argon, for several hours until the reaction was completed (monitored
by TLC). The solvent was then evaporated under reduced pressure and the crude residue was purified by
flash column chromatography (ether/hexane 1/99) using Et N pretreated (2 %) silica gel. The title
3
compound 14 was isolated as a yellowish oil (0.287 g, 0.466 mmol, 54 %).
1
TLC: R 0.40 (ether/hexane 5/95). H NMR (300 MHz, CDCl ): δ 0.19 (s, 9H), 0.94 (m, 15H), 1.35 (m,
f
3
6
1
7
H), 1.55 (m, 6H), 1.62 (s, 3H), 1.63 (s, 3H), 4.44 (d, 1H, J = 7.8), 5.42 (d, 1H, J = 7.8), 6.44 (d, 1H, J =
7.3), 6.69 (dd, 1H, J = 13.9, 10), 6.74 (dd, 1H, J = 17.3, 10), 7.06 (d, 1H, J = 13.9), 7.27-7.31 (m, 2H),
1
3
1
.52-7.56 (m, 2H). C NMR (75 MHz, CDCl ): δ -0,25, 9.53 ( J = 330), 13.70, 26.41, 26.86, 27.30
3
C-Sn
2
3
(
JC-Sn = 55), 29.11 ( J
= 20), 73.11, 79.69, 92.89, 101.18, 110.41, 125.99, 126.39, 127.72, 127.89,
C-Sn
1
1
28.32, 134.07, 134.73, 136.29, 136.56, 146.94. IR (CHCl ): ν 2958, 2927, 2871, 2253 (C≡C), 1556,
3
+
464, 1382, 1250, 1142, 1049, 908, 846, 734. MS (EI, 70 eV) (intensity): calc'd for (C H O SiSn )
3
2 52 2
4

+
+
6
15; found: 615 (1) [M] , 557 (10) [(M-OC(CH ) ] , 265 (20), 250 (56), 167 (100), 109 (19). Anal.
3
2
Calcd for C H O SiSn: C, 62.44; H, 8.51. Found: C, 62.27; H, 8.42.
3
2
52
2
tributyl((1E,3E)-4-{2-[(4R*,5R*)-5-ethynyl-2,2-dimethyl-1,3-dioxolan-4-yl]phenyl}buta-1,3-
dienyl)stannane (15)
O
O
O
O
NH4F
TMS
H
SnBu3
SnBu3
14
15
To a solution of the protected alcyne 14 (1.8 g, 2.9 mmol, 1 equiv) in freshly distilled CH Cl (9 mL)
2
2
was added a solution of NH F in water (6 mL, 45 %) and n-Bu NHSO (0.2 g, 0.58 mmol, 0.2 equiv).
4
4
4
The mixture was stirred at r.t. and monitored by TLC until starting material disappearance (a few min).
The mixture was then poured in water (10 mL) and extracted with CH Cl (2 x 10 mL) and Et O (10
2
2
2
mL). The combined organic layer was washed with brine, dried over Na SO and concentrated in vacuo.
2
4
The residue was purified by flash column chromatography (ether/hexane 1/99) using Et N pretreated (2
3
%) silica gel and gave the deprotected compound 15 as a yellowish oil (1.46 g, 2.69 mmol, 93 %).
1
TLC: R 0.36 (ether/hexane 5/95). H NMR (300 MHz, CDCl ): δ 0.96 (m, 15H), 1.37 (m, 6H), 1.56 (m,
f
3
6
6
7
2
1
1
H), 1.64 (s, 3H), 1.65 (s, 3H), 2.58 (d, 1H, J = 2.2), 4.50 (dd, 1H, J = 7.5, 2.2), 5.46 (d, 1H, J = 7.5),
.44 (d, 1H, J = 18.1), 6.69 (dd, 1H, J = 14.5, 9.7), 6.74 (dd, 1H, J = 18.1, 9.7), 7.04 (d, 1H, J = 14.5),
1
3
1
.29-7.32 (m, 2H), 7.52-7.57 (m, 2H). C NMR (75 MHz, CDCl ): δ 9.54 ( J = 337), 13.68, 26.11,
3
C-Sn
2
3
6,80, 27.24 ( JC-Sn = 55), 29.09 ( J = 22), 72.05, 75.46, 80.23, 80.58, 110.74, 126.01, 126.49, 127.66,
C-Sn
28.03, 128.43, 133.90, 134.52, 136.10, 136.46, 146.92. IR (CHCl ): ν 3307, 2958, 2927, 2872, 1574,
3
+
456, 1383, 1215, 1162, 1055, 1001, 908, 734. MS (EI, 70 eV): m/z (%) 485 (82) [M-OC(CH ) ] , 429
3
2
(
10), 178 (30). Anal. Calcd for C H O Sn: C, 64.10; H, 8.16. Found: C, 63.95; H, 8.05.
29
44
2
(5Z)-5-[3-((4R*,5R*)-2,2-dimethyl-5-{2-[(1E,3E)-4-(tributylstannyl)buta-1,3-dienyl]phenyl}-1,3-
dioxolan-4-yl)prop-2-ynylidene]cyclopent-1-en-1-yl trifluoromethanesulfonate (4a)
5

O
O
1)
H
O
O
OTf
OTf
SnBu3
Pd(PPh ) Cl , CuI,
1
5
3
2
2
PhH/ i-Pr NH, r.t.
OTf
2
2) TMS
(0,3 eq.)
7
Bu Sn
3
4a
To a solution of the deprotected alkyne 15 (1.46 g, 2.69 mmol, 1.1 equiv) and the bis-enoltriflate 7
0.919 g, 2.44 mmol, 1 equiv) in dry benzene (30 mL) was added the catalyst Pd(PPh ) Cl (0.07 g, 0.1
(
3
2
2
mmol, 0.04 equiv), CuI (0.0457 g, 0.24 mmol, 0.1 equiv) and anhydrous i-Pr NH (10 mL). The mixture
2
was then carefully degassed and placed under argon. Reaction at r.t., was monitored by TLC until the
disappearance of the bis-enoltriflate 7 (around 2 h). To elimitate the minor endo-enoltriflate product 16
(
versus the exo 4a), TMS-acetylene was added (0.1 mL, d = 0.695, 0.73 mmol, 0.3 equiv) in a kinetic
2
differentiation reaction . Thus the reaction mixture was stirred for an additional 2 h, then quenched by
addition of saturated aqueous NH Cl (10 mL) and extracted with Et O. The extract was washed with
4
2
water, brine, dried over Na SO and concentrated under reduced pressure. The crude product was
2
4
purified by flash column chromatography (ether/hexane 3/97) using Et N pretreated (2 %) silica gel and
3
gave the title product 4a as a yellow oil (1.48 g, 1.92 mmol, 79 %).
1
TLC: R 0.34 (ether/hexane 1/9). H NMR (300 MHz, CDCl ): δ 0.89-0.96 (m, 15H), 1.27-1.40 (m,
f
3
6
H), 1.49-1.56 (m, 6H), 1.61 (s, 6H), 2.52 (m, 2H), 2.43 (d, 1H, J = 7.7), 4.67 (dd, 1H, J = 7.7, 2.2), 5.43
(
(
d, 1H, J = 7.7), 5.46 (s br, 1H), 6.20 (s br, 1H), 6.37 (d, 1H, J = 18.6), 6.66 (dd, 1H, J = 13.8, 9.8), 6.71
1
3
dd, 1H, J = 18.6, 9.8), 7.04 (d, 1H, J = 13.8), 7.26-7.29 (m, 2H), 7.51-7.54 (m, 2H). C NMR (50
1
2
3
MHz, CDCl ): δ 9.51 ( J = 337), 13.68, 26.26, 26.32, 26.93, 27.28 ( J = 54), 28.79, 29.09 ( J
=
3
C-Sn
C-Sn
C-Sn
2
1
0), 73.02, 79.78, 82.99, 91.21, 98.41, 110.24, 118.49 (JC-F = 322), 125.93, 126.65, 127.61, 128.23,
2
3
28.42, 129.34, 134.03, 134.25, 134.99, 135.22 ( JC-Sn= 370), 136.60, 147.26 ( J = 288), 148.94. IR
C-Sn
(
CHCl ): ν 2957, 2929, 2871, 2250 (C≡C), 1575, 1427, 1382, 1214, 1142, 1050, 1002, 909, 866, 734.
3
+
+
MS (EI, 70 eV) (intensity): calc'd for (C H F O SSn ) 769; found: (%) 769 (1) [M] , 711 (66) [(M-
36 49 3 5
+
+
+
+
OC(CH ) )] , 695 (1) [(M-O C(CH ) )] , 636 (2) [(M-SO CF )] , 479 (2) [(M-Bu Sn)] , 322 (100), 251
3
2
2
3 2
2
3
3
(60), 195 (49).
(3aR*,7bR*,9aS*,13cR*)-2,2-dimethyl-3a,7b,9a,11,12,13c-
hexahydropentaleno[1',2':7,8]phenanthro[9,10-d][1,3]dioxole (1a)
and
(3aR*,13cR*)-2,2-dimethyl-3a,11,12,13c-tetrahydropentaleno[1',2':7,8]phenanthro[9,10-
d][1,3]dioxole (18a)
6

O
O
O
O
O
O
Pd(CH CN) Cl
2
3
2
H
+
LiCl, DMF, r.t.
OTf
H
Bu Sn
3
4
a
1a
18a
r.t.
A solution of the enoltriflate 4a (0.309 g, 0.4 mmol, 1 equiv), Pd(CH CN) Cl (0.0052 g, 0.02 mmol,
3
2
2
0
.05 equiv) and LiCl (0.034 g, 0.8 mmol, 2 equiv) in anhydrous DMF (12 mL) was carefully degassed
and placed under argon. The mixture was stirred at r.t. for 2 h 30 (monitored by TLC) and, as the
reaction was completed, the DMF was reduced in vacuo. The crude was directly purified by flash
column chromatography (ether/hexane 5/95) using Et N pretreated (2 %) silica gel without any aqueous
3
work-up. The cyclized products 1a and 18a were obtained as a yellow oil (0.0637 g, 0.193 mmol, 48 %).
We noted that compound 1a smoothly aromatized in 18a.
Data for 1a:
1
TLC: R 0.43 (ether/hexane 1/9). H NMR (500 MHz, C D ): δ 1.47 (s, 3H), 1.58 (s, 3H), 2.27-2.31 (m,
f
6
6
2
9
0
H), 2.54-2.60 (m, 2H), 3.66 (m, 1H), 3.89 (d br, 1H, J = 10.7), 4.16 (d, 1H, J = 9.6), 4.78 (d, 1H, J =
.6), 5.42 (dt, 1H, J = 4.6, 2.1), 6.26 (dddd, 1H, J = 9.2, 3.2, 1.9, 0.5), 6.51 (dddd, 1H, J = 9.2, 3.2, 1.9,
.5), 6.64 (s br, 1H), 7.13-7.20 (2t overlapped with 18a, 2H), 7.35 (dd, 1H, J = 7.3, 2.6), 7.74 (ddd, 1H,
1
3
J = 7.3, 2.6, 1.2). C NMR (75 MHz, CDCl ): δ 27.34, 27.53, 37.11, 40.84, 77.21, 78.03, 112.89,
3
1
15.20, 117.18, 120.29, 121.97, 124.28, 126.27, 126.86, 127.08, 128.67, 132.58, 134.22, 135.11, 136.54,
+
+
1
46.54, 153.79, 162.80. MS (EI, 70 eV) (intensity): calc'd for (C H O ) 330; found 330 (96) [M] ,
2
3 22 2
+
+
2
72 (100) [(M-OC(CH ) )] , 256 (28) [(M-O C(CH ) )] , 244 (92), 215 (85).
3
2
2
3 2
Data for 18a:
1
TLC: R 0.35 (ether/hexane 1/9). H NMR (500 MHz, C D ): δ 1.52 (s, 3H), 1.53 (s, 3H), 2.41-2.45 (m,
f
6
6
2
7
7
H), 2.62 (td, 2H, J = 4.4, 2.8), 4.93 (syst AB, 2H, JAB = 11, ∆ν = 25 Hz), 6.34 (td, 1H, J = 2.8, 1.8),
.14 (td, 1H, J = 7.4, 1.3), 7.17 (dd, 1H, J = 1.6, 0.7), 7.22 (d, 1H, J = 1.0 Hz), 7.52 (syst AB, 2H, JAB
=
1
3
.8, ∆ν = 52 Hz), 7.63 (dd, 1H, J = 7.5, 1.5), 7.69 (ddd, 1H, J = 7.2, 1.2, 1.2). C NMR (75 MHz,
CDCl ): δ 23.31, 27.33, 27.38, 39.46, 79.52, 80.19, 113.49, 115.03, 119.75, 121.26, 122.54, 124.84,
3
1
2
25.79, 127.66, 127.68, 130.13, 132.56, 133.69, 134.21, 134.96, 146.36, 149.37, 155.48. IR (CHCl ): ν
927, 2857, 1774, 1702, 1458, 1377, 1235, 1213, 1054, 840, 774. MS (EI, 70 eV) (intensity): calc'd for
3
+
+
+
(C H O ) 328; found 328 (40) [M] , 270 (96) [(M-OC(CH ) ] , 242 (100).
23 20 2
3 2
(1R*,2R*)-1-(2-bromo-5-methoxyphenyl)-4-(trimethylsilyl)but-3-yne-1,2-diol (10b) and (1S*,2R*)-
1
-(2-bromo-5-methoxyphenyl)-4-(trimethylsilyl)but-3-yne-1,2-diol (10b anti)
7

O
O
TMS
CHO
HO OH
HO OH
Br
Li
OMe
OMe
Br
+
THF, -78°C
TMS
TMS
Br
MeO
1
0b
1
0b anti
A solution of n-butyllithium (3.92 mL, 6.045 mmol, 1.3 equiv, 1.54 M in hexane) was added to a dried
round-bottom flask containing 3-(1-methoxy-1-methyl-ethoxy)-prop-1-ynyl]-trimethylsilyl (1.211 g,
6
.045 mmol, 1.3 equiv) in freshly distilled THF (10 mL) at -78 °C. The reaction was stirred 30 min at
3
this temperature and then cannulated to a solution of 2-bromo-5-methoxy-benzaldehyde (1.00 g, 4.650
mmol, 1 equiv) in THF (20 mL) kept at -78 °C. The mixture was stirred for 1 h at -78 °C and then
quenched by addition of saturated aqueous NaHCO (10 mL) and water (30 mL). After extraction with
3
Et O, the combined organic layers were washed with water, brine, dried over MgSO and concentrated
2
4
in vacuo. The crude product was dissolved in methanol (30 mL) containing PPTS (0.301 g, 1.2 mmol,
.1 equiv). The solution was stirred for 30 min at r.t. and quenched with the addition of brine (40 mL).
0
The mixture was extracted with Et O and the combined extracts were washed with water, brine and dried
2
over MgSO . Silica gel column chromatography (ether/hexane 5/95) afforded compound 10b (0.758 g,
4
2
9
.209 mmol) as a yellowish oil and 10b anti (0.758 g, 2.209 mmol) as a white solid for a global yield of
5 %.
Data for 10b:
TLC: R 0.18 (ether/hexane 5/5). H NMR (200 MHz, CDCl ): δ 0.16(s, 9H), 2.42 (s br, 1H, OH), 3.13
1
f
3
(
s br, 1H, OH), 3.81 (s, 3H), 4.56 (t br, 1H, J = 4.6), 5.17 (d br, 1H, J = 4.6), 6.75 (dd, 1H, J = 8.5, 3.2),
1
3
7
9
2
.12 (d, 1H, J = 3.2), 7.43 (d, 1H, J = 8.5). C NMR (75 MHz, CDCl ): δ -0.35, 55.45, 66.35, 75.30,
3
1.79, 102.63, 113.18, 114.11, 115.61, 133.15, 139.18, 158.95. IR (neat): ν 3284 (br, OH), 2956, 2839,
176 (C≡C), 1603, 1577, 1460, 1419, 1250, 1161, 1137, 1040, 1011, 940, 849, 760. MS (ESI, positive
+
81
+
ion 150 eV) (intensity): calc'd for (C H BrO SiNa ) 365.02; found: 367.03 (100) [M +Na] , 365.03
1
4
19
3
7
9
+
(95) [M +Na] . Anal. Calcd for C H BrO Si: C, 48.98; H, 5.58. Found: C, 49.05; H, 5.44.
14
19
3
Data for 10b anti:
1
TLC: R 0.28 (ether/hexane 5/5). mp 120-122 °C. H NMR (300 MHz, CDCl ): δ 0.13 (s, 9H), 2.60 (d,
f
3
1
4
H, J = 6.8, OH), 2.81 (d, 1H, J = 4.4, OH), 3.82 (s, 3H), 4.71 (dd, 1H, J = 6.8, 4.4), 5.21 (t, 1H, J =
1
3
.4), 6.75 (dd, 1H, J = 8.7, 3.1), 7.23 (d, 1H, J = 3.1), 7.40 (d, 1H, J = 8.7). C NMR (75 MHz, CDCl ):
3
δ -0.35, 55.39, 65.93, 74.65, 92.79, 101.69, 112.33, 114.43, 115.45, 132.82, 138.93, 158.88.
[((4R*,5R*)-5-{5-methoxy-2-[(E)-2-(tributylstannyl)ethenyl]phenyl}-2,2-dimethyl-1,3-dioxolan-4-
yl)ethynyl](trimethyl)silane (12b) via {[(4R*,5R*)-5-(2-bromo-5-methoxyphenyl)-2,2-dimethyl-1,3-
dioxolan-4-yl]ethynyl}(trimethyl)silane (D)
8

SnBu3
O
O
O
TMS
OH OH
Br
O
O
Bu Sn
11
3
MeO
O
MeO
MeO
TMS
pTsOH, acetone
TMS
Pd(PPh ) , PhH, 80°C
3 4
Br
SnBu3
10b
D
12b
A solution of compound 10b (7.269 g, 21.175 mmol, 1 equiv), 2,2-dimethoxypropane (13 mL, d =
.847, 105.873 mmol, 5 equiv) and p-TsOH (0.403 g, 2.117 mmol, 0.1 equiv) in acetone (100 mL) was
0
stirred at r.t. for 30 min. The mixture was when added to brine (50 mL) and extracted with Et O. The
2
combined organic extract was washed with water, brine and dried over MgSO . After evaporation of the
4
solvents in vacuo, the residue was purified by silica gel flash column chromatography (ether/hexane
1
0/90) to give the protected diol D as a yellowish oil (8.117 g, 21.174 mmol, 100 %).
1
TLC: R 0.25 (ether/hexane 5/95). H NMR (300 MHz, CDCl ): δ 0.18 (s, 9H), 1.61 (s, 3H), 1.64 (s,
f
3
3
3
9
2
H), 3.80 (s, 3H), 4.43 (d, 1H, J = 6.8), 5.49 (d, 1H, J = 6.8), 6.75 (dd, 1H, J = 9.0, 3.0), 7.09 (d, 1H, J =
1
3
.0), 7.45 (d, 1H, J = 9.0). C NMR (75 MHz, CDCl ): δ -0.35, 26.39, 27.00, 55.44, 73.13, 81.60,
3
2.80, 101.63, 111.13, 113.25, 113.49, 115.56, 133.64, 138.08, 159.23. IR (neat): ν 3078, 2958, 2850,
836, 2177 (C≡C), 1580, 1470, 1380, 1250, 1165, 1055, 840, 761. MS (ESI, positive ion 180 eV)
+
81
+
(
[
intensity): calc'd for (C H BrO SiNa ) 405.05; found: 407.08 (100) [M +Na] , 405.08 (93)
17 23 3
79
+
M +Na] . Anal. Calcd for C H BrO Si: C, 53.26; H, 6.05. Found: C, 53.06; H, 6.24.
17
23
3
A solution of the protected diol D (3.601 g, 9.393 mmol, 1 equiv), trans-1,2-bis(tributylstannyl)ethylene
1 (7.402 g, 12.211 mmol, 1.3 equiv) and Pd(PPh ) (0.543 g, 0.470 mmol, 0.05 equiv) in dry degassed
1
3
4
benzene (50 mL) was heated at reflux, under argon, for several hours until the reaction was completed
monitored by TLC). The solvent was then evaporated under reduced pressure and the crude residue was
(
purified by flash column chromatography (hexane) using Et N pretreated (2 %) silica gel. The title
3
compound 12b was isolated as a yellowish oil (3.841 g, 6.2 mmol, 66 %).
1
TLC: R 0.33 (ether/hexane 5/95). H NMR (200 MHz, CDCl ): δ 0.20 (s, 9H), 0.89-0.99 (m, 15H),
f
3
1
7
.28-1.48 (m, 6H), 1.53-1.65 (m, 6H), 1.63 (s, 6H), 3.86 (s, 3H), 4.62 (d, 1H, J = 7.3), 5.37 (d, 1H, J =
.3), 6.65 (d, 1H, J = 19.2), 6.89 (dd, 1H, J = 8.6, 2.6), 7.08 (d, 1H, J = 2.6), 7.32 (d, 1H, J = 19.2), 7.49
1
3
1
2
(
d, 1H, J = 8.6). C NMR (50 MHz, CDCl ): δ -0.28, 9.6 ( J = 336), 13.72, 26.24, 27.02, 27.29 ( J
3
C-Sn
C-Sn
3
=
55), 29.14 ( J
= 20), 55.26, 72.69, 80.01, 92.56, 101.46, 110.55, 111.80, 114.19, 127.93, 131.94,
C-Sn
1
1
32.50, 134.23, 142.90, 159.12. IR (neat): ν 2953, 2925, 2861, 2842, 2172 (C≡C), 1608, 1590, 1493,
466, 1378, 1291, 1250, 1162, 1052, 988. MS (ESI, positive ion 135 eV) (intensity): calc'd for
+
+
(C H O SiSnNa ) 641.3; found: 641.3 (100) [M+Na] .
31 52 3
[((4R*,5R*)-5-{2-[(E)-2-bromoethenyl]-5-methoxyphenyl}-2,2-dimethyl-1,3-dioxolan-4-
yl)ethynyl](triethyl)silane (13b)
9

O
O
O
Br2
O
TMS
TMS
CCl , -20°C
4
MeO
MeO
SnBu3
Br
12b
13b
To a cold (-20 °C) stirred solution of vinylstannane 12b (3.150 g, 5.084 mmol, 1 equiv) in CCl (30 mL)
4
was added dropwise (slowly) a solution of bromine (1M in CCl , 5.09 mL, 5.09 mmol, 1 equiv). The
4
mixture was stirred for 5 min, the solvent was then evaporated under reduced pressure and the crude
product purified by silica gel flash column chromatography (ether/hexane 5/95) to afford the vinyl
bromine 13b as a yellowish oil ( 1.909 g, 4.663 mmol, 92 %).
1
TLC: R 0.19 (ether/hexane 5/95). H NMR (200 MHz, CDCl ): δ 0.21 (s, 9H), 1.61 (s, 3H) 1.62 (s,
f
3
3
8
H), 3.82 (s, 3H), 4.39 (d, 1H, J = 7.6), 5.27 (d, 1H, J = 7.6), 6.55 (d, 1H, J = 13.7), 6.84 (dd, 1H, J =
1
3
.5, 2.7), 7.07 (d, 1H, J = 2.7), 7.29 (d, 1H, J = 8.5), 7.6 (d, 1H, J = 13.7). C NMR (50 MHz, CDCl ):
3
δ -0.30, 26.26, 26.77, 55.24, 73.02, 79.79, 93.38, 100.95, 106.66, 110.68, 111.72, 114.13, 127.76,
1
1
28.02, 134.39, 135.62, 159.91. IR (CHCl ): ν 2959, 2172 (C≡C), 1608, 1500, 1434, 1381, 1299, 1251,
3
+
164, 1056, 845, 761. MS (ESI, positive ion 135 eV) (intensity): calc'd for (C H BrO SiNa ) 431.06;
1
9 25
3
81
+
79
+
found: 433.08 (100) [M +Na] , 431.05 (95) [M +Na] .
[((4R*,5R*)-5-{5-methoxy-2-[(1E,3E)-4-(tributylstannyl)buta-1,3-dienyl]phenyl}-2,2-dimethyl-1,3-
dioxolan-4-yl)ethynyl](trimethyl)silane (14b)
Bu Sn
3
O
O
O
O
1
1
SnBu3
Pd(PPh ) , PhH, 80°C
MeO
TMS
3
4
MeO
TMS
Br
SnBu3
13b
14b
A solution of compound 13b (0.873 g, 2.132 mmol, 1 equiv), trans-1,2-bis(tributylstannyl)ethylene 11
1.68 g, 2.772 mmol, 1.3 equiv) and Pd(PPh ) (123 mg, 0.107 mmol, 0.05 equiv) in dry degassed
(
3
4
benzene (60 mL) was heated at reflux, under argon, for several hours until the reaction was completed
monitored by TLC). The solvent was then evaporated under reduced pressure and the crude residue was
(
purified by flash column chromatography (hexane) using Et N pretreated (2 %) silica gel. The title
3
compound 14b was isolated as a yellowish oil (0.418 g, 0.647 mmol, 47 %).
1
TLC: R 0.23 (ether/hexane 5/95). H NMR (200 MHz, CDCl ): δ 0.18 (s, 9H), 0.88-0.98 (m, 15H),
f
3
1
.25-1.42 (m, 6H), 1.49-1.58 (m, 6H), 1.62 (s, 3H), 1.63 (s, 3H), 3.83 (s, 3H), 4.42 (d, 1H, J = 7.6), 5.40
1
0

(
d, 1H, J = 7.6), 6.36 (d, 1H, J = 18), 6.61 (dd, 1H, J = 14.4, 9.2), 6.70 (dd, 1H, J = 18, 9.2), 6.85 (dd,
1
3
1
H, J = 8.8, 2.9), 6.97 (d, 1H, J = 14.4), 7.07 (d, 1H, J = 2.9), 7.50 (d, 1H, J = 8.8). C NMR (50 MHz,
1
2
3
CDCl ): δ -0,24, 9.52 ( J
= 330), 13.70, 26.40, 26.85, 27.30 ( J
= 54), 29.12 ( J
= 20), 55.24,
3
C-Sn
C-Sn
C-Sn
7
1
8
3.16, 79.53, 92.98, 101.18, 110.51, 111.32, 114.16, 127.29, 127.52, 129.11, 133.00, 134.81, 135.76,
47.15, 159.36. IR (neat): ν 2956, 2926, 2860, 2176 (C≡C), 1606, 1556, 1494, 1464, 1379, 1250, 1055,
+
41, 761. MS (ESI, positive ion 135 eV) ) (intensity): calc'd for (C H O SiSn ) 643.94; found: 643.95
3
3 54 3
+
(100) [M] .
tributyl((1E,3E)-4-{2-[(4R*,5R*)-5-ethynyl-2,2-dimethyl-1,3-dioxolan-4-yl]-4-
methoxyphenyl}buta-1,3-dienyl)stannane (15b)
O
O
O
O
NH4F
MeO
TMS
MeO
H
SnBu3
SnBu3
1
4b
15b
To a solution of the protected alcyne 14b (0.459 g, 0.711 mmol, 1 equiv) in freshly distilled CH Cl (5
2
2
mL) was added a solution of NH F in water (0.9 mL, 45 %) and n-Bu NHSO (0.048 g, 0.142 mmol, 0.2
4
4
4
equiv). The mixture was stirred at r.t. for one hour. The mixture was then poured in water (5 mL) and
extracted with CH Cl (2 x 10 mL) and Et O (10 mL). The combined organic layer was washed with
2
2
2
brine, dried over MgSO and concentrated in vacuo. The residue was purified by flash column
4
chromatography (hexane) using Et N pretreated (2 %) silica gel and gave the deprotected compound 15b
3
as a yellowish oil (0.407 g, 0.711 mmol, 100 %).
1
TLC: R 0.52 (ether/hexane 1/9). H NMR (200 MHz, CDCl ): δ 0.88-0.99 (m, 15H), 1.25-1.40 (m, 6H),
f
3
1
2
9
.43-1.60 (m, 6H), 1.63 (s, 3H), 1.64 (s, 3H), 2.58 (d, 1H, J = 2.0), 3.83 (s, 3H), 4.46 (dd, 1H, J = 7.3,
.0), 5.44 (d, 1H, J = 7.3), 6.35 (d, 1H, J = 18.1), 6.60 (dd, 1H, J = 14.7, 9.5), 6.69 (dd, 1H, J = 18.1,
1
3
.5), 6.86 (dd, 1H, J = 8.7, 2.7), 6.94 (d, 1H, J = 14.7), 7.08 (d, 1H, J = 2.7), 7.50 (d, 1H, J = 8.7). C
1
2
3
NMR (50 MHz, CDCl ): δ 9.58 ( J = 339), 13.70, 26.13, 26.84, 27.28 ( J = 54), 28.91 ( J = 21),
5
3
C-Sn
C-Sn
C-Sn
1
5.26, 72.19, 75.55, 80.03, 80.68, 110.86, 111.57, 114.12, 127.33, 127.73, 128.94, 132.75, 134.61 ( JC-Sn
2
=
370), 135.73, 147.17 ( JC-Sn = 47), 159.33. IR (neat): ν 3307, 2956, 2925, 1606, 1558, 1493, 1377,
+
1
252, 1053, 1000, 874, 660. MS (ESI, positive ion 135 eV) (intensity): calc'd for (C H O SnNa )
3
0 46 3
+
5
97.33; found: 597.88(100) [M+Na] . Anal. Calcd for C H O Sn: C, 62.84; H, 8.09. Found: C, 63.18;
3
0
46
3
H, 8.45.
(5Z)-5-[3-((4R*,5R*)-5-{5-methoxy-2-[(1E,3E)-4-(tributylstannyl)buta-1,3-dienyl]phenyl}-2,2-
dimethyl-1,3-dioxolan-4-yl)prop-2-ynylidene]cyclopent-1-en-1-yl trifluoromethanesulfonate (4b)
1
1

O
O
1
) MeO
H
O
O
OMe
OTf
OTf
SnBu3
1
5b
Pd(PPh ) Cl , CuI,
PhH/ i-Pr NH, r.t.
3
2
2
2
OTf
2
) TMS
(0,3 eq.)
7
4b
Bu Sn
3
To a solution of the deprotected alkyne 15b (0.543 g, 0.947 mmol, 1.1 equiv) and the bis-enoltriflate 7
(
0.324 g, 0.861 mmol, 1 equiv) in dry benzene (7.5 mL) was added the catalyst Pd(PPh ) Cl (0.024 g,
3
2
2
0
.0344 mmol, 0.04 equiv), CuI (0.024 g, 0.129 mmol, 0.15 equiv) and anhydrous i-Pr NH (2.5 mL). The
2
mixture was then carefully degassed and placed under argon. Reaction at r.t., was monitored by TLC
until the disappearance of the bis-enoltriflate 7 (2 h). To elimitate the minor endo-enoltriflate product
1
6b (versus the exo 4b), TMS-acetylene was added (0.04 mL, d = 0.695, 0.258 mmol, 0.3 equiv) in a
2
kinetic differentiation reaction . Thus the reaction mixture was stirred for an additional 2 h, then
quenched by addition of saturated aqueous NH Cl (7 mL) and extracted with Et O. The extract was
4
2
washed with water, brine, dried over MgSO and concentrated under reduced pressure. The crude
4
product was purified by flash column chromatography (ether/hexane 0/100 to 5/95) using Et N
3
pretreated (2 %) silica gel and gave the title product 4b as a yellow oil (0.536 g, 0.670 mmol, 78 %).
1
TLC: R 0.18 (ether/hexane 1/9). H NMR (300 MHz, CDCl ): δ 0.89-0.95 (m, 15H), 1.27-1.40 (m,
f
3
6
1
1
1
2
1
1
1
H), 1.47-1.61 (m, 6H), 1.61 (s br, 6H), 2.51-2.55 (m, 2H), 2.72-2.73 (m, 2H), 3.83 (s, 3H), 4.64 (dd,
H, J = 7.5, 2.2), 5.36 (d, 1H, J = 7.5), 5.48 (s br, 1H), 6.21 (s br, 1H), 6.30 (d, 1H, J = 18.3), 6.56 (dd,
H, J = 14.9, 9.8), 6.70 (dd, 1H, J = 18.3, 9.8), 6.83 (dd, 1H, J = 8.6, 3), 6.96 (d, 1H, J = 14.9), 7.08 (d,
1
3
1
H, J = 3), 7.47 (d, 1H, J = 8.6). C NMR (75 MHz, CDCl ): δ 9.52 ( JC-Sn= 336), 13.69, 26.27, 26.34,
3
2
3
6.95, 27.29 ( J
= 53), 28.81, 29.12 ( J
= 20), 55.25, 73.14, 79.67, 83.08, 91.34, 98.45, 110.36,
C-Sn
C-Sn
1
11.54, 114.21, 118.53 ( J = 322), 127.24, 128.12, 129.12, 129.34, 132.48, 133.70, 135.79, 147.30,
C-F
47.50, 148.97, 159.29. IR (neat): ν 2957, 2926, 2853, 2253 (C≡C), 1605, 1557, 1492, 1426, 1380,
289, 1215, 1142, 1044, 1003, 910, 814, 736. MS (ESI, positive ion 135 eV) (intensity): calc'd for
+
+
(C H F O SSnNa ) 823.32; found: 823.27 (82) [M+Na] , 743.22 (100).
37 51 3 6
(3aR*,7bR*,9aS*,13cR*)-5-methoxy-2,2-dimethyl-3a,7b,9a,11,12,13c-
hexahydropentaleno[1',2':7,8]phenanthro[9,10-d][1,3]dioxole (1b)
and
(3aR*,13cR*)-5-methoxy-2,2-dimethyl-3a,11,12,13c-
tetrahydropentaleno[1',2':7,8]phenanthro[9,10-d][1,3]dioxole (18b)
1
2

O
O
OMe
+
OMe
O
O
OMe
O
O
Pd(CH CN) Cl
2
3
2
H
LiCl, DMF, r.t.
OTf
H
Bu Sn
3
4
b
1b
18b
r.t.
A solution of the enoltriflate 4b (0.247 g, 0.309 mmol, 1 equiv), Pd(CH CN) Cl (0.004 g, 0.0154 mmol,
3
2
2
0
.05 equiv) and LiCl (0.026 g, 0.6178 mmol, 2 equiv) in anhydrous DMF (15 mL) was carefully
degassed and placed under argon. The mixture was stirred at r.t. for 2 h (monitored by TLC) and, as the
reaction was completed, the DMF was reduced in vacuo. The crude was directly purified by flash
column chromatography (hexane) using Et N pretreated (2 %) silica gel without any aqueous work-up.
3
The cyclized products 1b and 18b were obtained as a yellow oil (0.068 g, 0.190 mmol, 61 %). We noted
that compound 1b smoothly aromatized in 18b.
Data for 1b:
1
TLC: R 0.43 (ether/hexane 25/75). H NMR (200 MHz, CDCl ): δ 1.64 (s br, 6H), 2.59 (m, 2H), 2.87
f
3
(
m, 2H), 3.74 (m, 1H), 4.02 (m, 1H), 4.14 (m, 1H), 4.74 (d, 1H, J = 9.3), 5.66 (tt, 1H, J = 1.7, 0.48), 6.29
d br, 1H, J = 9.8), 6.31 (s br, 1H), 6.59 (d br, 1H, J = 9.8), 6.82 (m overlapped with 18b, 1H), 7.40 (dd,
(
1
3
1
3
1
3
H, J = 8.3, 3.4), 7.60 (d, 1H, J = 8.3). C NMR (50 MHz, CDCl ): δ 27.36, 29.70, 29.70, 30.16, 37.12,
3
9.44, 55.44, 79.54, 80.24, 108.39, 125.51, 126.63, 126.84, 126.95, 128.34, 131.32, 134.22, 136.44,
+
38.26, 138.35, 144.58, 147.17, 154.12, 155.85. MS (EI, 70 eV) (intensity): calc'd for (C H O )
2
4 24 3
+
+
60.2; found: 360.2 (45) [M] , 358.1 (100) [18b] , 300.1 (78), 272.1 (60), 149.0 (70), 113.2 (29), 69.1
(23), 57.2 (31).
Data for 18b:
TLC: R 0.38 (ether/hexane 25/75). H NMR (300 MHz, CDCl ): δ 1.64 (s br, 6H), 2.79 (dddd, 2H, J =
1
f
3
2
6
2
3
1
1
.5, 2.2, 1.9, 1.8), 3.14 (dd, 2H, J = 2.5, 1.9), 3.90 (s, 3H), 4.84 (syst AB, 2H, JAB = 10.9, ∆ν = 15.3 Hz),
.78 (q, 1H, J = 2.5), 6.83 (s br, 1H), 6.91 (dd, 1H, J = 8.4, 2.8), 7.06 (d br, 1H, J = 2.8), 7.51 (syst AB,
1
3
H, JAB = 7.8, ∆ν = 35.6 Hz), 7.68 (d, 1H, J = 8.4). C NMR (75 MHz, CDCl ): δ 23.36, 27.41, 27.41,
3
9.47, 55.42, 79.62, 80.29, 107.81, 113.60, 113.60, 115.04, 119.09, 121.29, 124.94, 126.38, 129.30,
32.57, 133.72, 136.57, 140.21, 146.39, 149.42, 155.49, 159.48. IR (CHCl ): ν 3019, 2929, 2854, 1685,
3
605, 1566, 1490, 1414, 1376, 1299, 1216, 1175, 1085, 1059, 1027, 763. MS (EI, 70 eV) (intensity):
+
+
+
calc'd for (C H O ) 358.1; found: 358.1 (100) [M] , 300.1 (94) [M-OC(CH ) )] , 272.1 (74), 257.1
2
4 22 3
3 2
(51), 227.1 (35), 113.1 (29), 69.2 (26), 57.2 (46).
1
3

(
(
1R*,2R*)-1-(2-bromo-4,5-dimethoxyphenyl)-4-(triethylsilyl)but-3-yne-1,2-diol (10c) and
1S*,2R*)-1-(2-bromo-4,5-dimethoxyphenyl)-4-(triethylsilyl)but-3-yne-1,2-diol (10c anti) (named
"
5,6-dimethoxy" for convenience in the communication)
O
O
TES
CHO
OMe
HO OH
Br
HO OH
Li
OMe
OMe
OMe
OMe
Br
+
THF, -78°C
TES
TES
Br
MeO
1
0c
1
0c anti
A solution of n-butyllithium (35.5 mL, 53.046 mmol, 1.3 equiv, 1.494 M in hexane) was added to a
dried round-bottom flask containing 3-(1-methoxy-1-methyl-ethoxy)-prop-1-ynyl]-trimethylsilyl (12.86
g, 53.046 mmol, 1.3 equiv) in freshly distilled THF (45 mL) at -78 °C. The reaction was stirred 30 min
at this temperature and then cannulated to a solution of 2-bromoveratraldehyde (10 g, 40.805 mmol, 1
equiv) suspended in a THF/ether solution (45/45 mL) kept at -5 °C. The mixture was stirred for 10 min
at this temperature and then poured into saturated aqueous NaHCO (50 mL). After washing with water
3
(
30 mL) and extraction with Et O, the combined organic layers were washed with water, brine, dried
2
over MgSO and concentrated in vacuo. The crude product, containing the protected alcohols as an oil,
4
was dissolved in methanol (120 mL) containing PPTS (1.025 g, 4.08 mmol, 0.1 equiv). The solution was
stirred for 30 min at r.t. and quenched with the addition of brine (50 mL). The mixture was extracted
with Et O and the combined extracts were washed with water, brine and dried over Na SO . Silica gel
2
2
4
column chromatography (ether/hexane 3/7) afforded compound 10c (7.882 g, 18.975 mmol) as a
yellowish oil and 10c anti (7.882 g, 18.975 mmol) as a white solid for a global yield of 93 %.
Data for 10c:
1
TLC: R 0.08 (ether/hexane 3/7). H NMR (300 MHz, CDCl ): δ 0.57 (q, 6H,J = 7.9), 0.93 (t, 9H, J =
f
3
7
.9), 2.51 (s br, 1H, OH), 2.95 (s br, 1H, OH), 3.86 (s, 3H), 3.88 (s, 3H), 4.54 (d br, 1H, J = 5.6), 5.13 (d
1
3
br, 1H, J = 5.6), 6.99 (s, 1H), 7.04 (s, 1H). C NMR (75 MHz, CDCl ): δ 4.10, 7.33, 56.02, 56.15,
3
6
6.72, 75.49, 89.45, 103.70, 111.01, 113.20, 115.31, 130.23, 148.53, 149.30. IR (CCl ): ν 3466 (br,
4
OH), 3003, 2956, 2875, 2176 (C≡C), 1604, 1503, 1450, 1260, 1160, 1053, 787, 782. MS (ESI, positive
+
81
+
ion 135 eV) (intensity): calc'd for (C H BrO SiNa ) 437.08; found: 439.95 (95) [M +Na] , 437.08
18 27
4
7
9
+
(
.
100) [M +Na] .
Data for 10c anti:
TLC: R 0.16 (ether/hexane 3/7). mp 128-130 °C. H NMR (300 MHz, CDCl ): δ 0.56 (q, 6H, J = 7.9),
1
f
3
0
.93 (t, 9H, J = 7.9), 2.52 (s br, 1H, OH), 2.80 (s br, 1H, OH), 3.87 (s, 3H), 3.90 (s, 3H), 4.73 (d br, 1H,
1
4

1
3
J = 3.9), 5.15 (d br, 1H, J = 3.9), 6.99 (s, 1H), 7.21 (s, 1H). C NMR (75 MHz, CDCl ): δ 4.15, 7.33,
3
5
5.96, 56.16, 66.35, 74.53, 90.40, 103.11, 111.19, 112.19, 115.07, 130.10, 148.44, 149.21.
[((4R*,5R*)-5-{4,5-dimethoxy-2-[(E)-2-(tributylstannyl)ethenyl]phenyl}-2,2-dimethyl-1,3-dioxolan-
4
1
-yl)ethynyl](triethyl)silane (12c) via {[(4R*,5R*)-5-(2-bromo-4,5-dimethoxyphenyl)-2,2-dimethyl-
,3-dioxolan-4-yl]ethynyl}(triethyl)silane (E) (named "5,6-dimethoxy" for convenience in the
communication)
SnBu3
O
O
O
O
O
TES
OH OH
MeO
MeO
MeO
Bu Sn
3
O
11
TES
MeO
MeO
TES
pTsOH, acetone
Br
Pd(PPh ) , PhH, 80°C
3 4
MeO
Br
SnBu3
10c
E
12c
A solution of compound 10c (4.286 g, 10.318 mmol, 1 equiv), 2,2-dimethoxypropane (6.34 mL, d =
.847, 51.589 mmol, 5 equiv) and p-TsOH (0.196 g, 1.032 mmol, 0.1 equiv) in acetone (80 mL) was
0
stirred at r.t. for 30 min. The mixture was when added to brine (50 mL) and extracted with Et O. The
2
combined organic extract was washed with water, brine and dried over MgSO . After evaporation of the
4
solvents in vacuo, the residue was purified by silica gel flash column chromatography (ether/hexane
5
/95) to give the protected diol E as a yellowish oil (4.700 g, 10.318 mmol, 100 %).
1
TLC: R 0.24 (ether/hexane 7/93). H NMR (200 MHz, CDCl ): δ 0.62 (q, 6H, J = 7.8), 0.99 (t, 9H, J =
f
3
7
7
1
2
.8), 1.61 (s, 3H), 1.64 (s, 3H), 3.88 (s, 6H), 4.46 (d, 1H, J = 6.9), 5. 49 (d, 1H, J = 6.9), 7.00 (s, 1H),
1
3
.01 (s, 1H). C NMR (50 MHz, CDCl ): δ 4.15, 7.38, 26.11, 27.02, 55.92, 56.16, 73.05, 81.89, 90.05,
3
03.23, 110.21, 111.00, 113.15, 115.47, 129.02, 148.76, 149.48. IR (neat): ν 3088, 2956, 2875, 2841,
175 (C≡C), 1603, 1514, 1440, 1256, 1058, 860, 725. MS (ESI, positive ion 135 eV) (intensity): calc'd
+
81
+
79
+
for (C H BrO SiNa ) 477.11; found: 479.62 (100) [M +Na] , 477.62 (75) [M +Na] . Anal. Calcd for
21 31
4
C H BrO Si: C, 55.38; H, 6.86. Found: C, 55.88; H, 7.24.
21
31
4
A solution of the protected diol E (4.323 g, 9.491 mmol, 1 equiv), trans-1,2-bis(tributylstannyl)ethylene
1 (7.479 g, 12.339 mmol, 1.3 equiv) and Pd(PPh ) (0.548 g, 0.474 mmol, 0.05 equiv) in dry degassed
1
3
4
benzene (65 mL) was heated at reflux, under argon, for several hours until the reaction was completed
monitored by TLC). The solvent was then evaporated under reduced pressure and the crude residue was
(
purified by flash column chromatography (ether/hexane 0/100 to 1/99) using Et N pretreated (2 %) silica
3
gel. The title compound 12c was isolated as a yellowish oil (4.119 g, 5.955 mmol, 63 %).
1
TLC: R 0.28 (ether/hexane 2/8). H NMR (300 MHz, CDCl ): δ 0.59 (q, 6H, J = 7.9), 0.89-1.02 (t, 9H,
f
3
J = 7.9 overlapped with m, 15H), 1.29-1.44 (m, 6H), 1.52-1.62 (m, 6H), 1.59 (s, 3H), 1.60 (s, 3H), 3.89
s, 3H), 3.93 (s, 3H), 4.63 (d, 1H, J = 7.5), 5.32 (d, 1H, J = 7.5), 6.63 (d, 1H, J = 19.2), 6.89 (s, 1H),
(
1
5

1
3
1
7
2
1
2
.02 (s, 1H), 7.30 (d, 1H, J = 19.2). C NMR (50 MHz, CDCl ): δ 4.15, 7.36, 9.67 ( JC-Sn= 336), 13.69,
3
2
3
5.95, 27.05, 27.29 ( J
= 55), 29.14 ( J
= 20), 55.84, 55.87, 72.41, 80.62, 89.74, 103.08, 109.20,
C-Sn
C-Sn
1
2
09.94, 110.37, 124.99, 131.87 ( J = 337), 132.69 ( J = 64), 142.79, 148.64, 149.14. IR (neat): ν
C-Sn
C-Sn
956, 2873, 2173 (C≡C), 1607, 1509, 1464, 1378, 1212, 1050, 865, 739, 727. MS (ESI, positive ion 150
+
+
eV) (intensity): calc'd for (C H O SiSnNa ) 715.42; found: m/z (%) 715.58 (100) [M+Na] .
3
5 60 4
[((4R*,5R*)-5-{2-[(E)-2-bromoethenyl]-4,5-dimethoxyphenyl}-2,2-dimethyl-1,3-dioxolan-4-
yl)ethynyl](triethyl)silane (13c) (named "5,6-dimethoxy" for convenience in the communication)
O
O
O
TES
Br2
O
TES
CCl , -20°C
4
MeO
MeO
MeO
MeO
SnBu3
Br
1
2c
13c
To a cold (-20 °C) stirred solution of vinylstannane 12c (4.024 g, 5.818 mmol, 1 equiv) in CCl (50 mL)
4
was added dropwise (slowly) a solution of bromine (1M in CCl , 5.82 mL, 5.82 mmol, 1 equiv). The
4
mixture was stirred for 5 min, the solvent was then evaporated under reduced pressure and the crude
product purified by silica gel flash column chromatography (ether/hexane 1/99 to 3/97) to afford the
vinyl bromine 13c as a yellowish oil (2.800 g, 5.817 mmol, 100 %).
1
TLC: R 0.18 (ether/hexane 2/8). H NMR (300 MHz, CDCl ): δ 0.64 (q, 6H, J = 7.9), 0.99 (t, 9H, J =
f
3
7
.9), 1.61 (s br, 6H), 3.89 (s, 3H), 3.90 (s, 3H), 4.43 (d, 1H, J = 7.5), 5. 26 (d, 1H, J = 7.5), 6.59 (d, 1H,
1
3
J = 13.7), 6.81 (s, 1H), 6.98 (s, 1H), 7.58 (d, 1H, J = 13.7). C NMR (50 MHz, CDCl ): δ 4.14, 7.44,
3
2
1
1
6.07, 26.86, 55.77, 55.80, 73.03, 80.21, 90.59, 102.58, 107.02, 109.23, 109.32, 110.63, 126.55, 127.88,
34.38, 148.99, 149.41. IR (CHCl ): ν 2955, 2772, 2167 (C≡C), 1610, 1550, 1465, 1380, 1272, 1220,
3
+
108, 1055, 913, 742. MS (ESI, positive ion 135 eV) (intensity): calc'd for (C H BrO SiNa ) 503.12;
2
3 33
4
81
+
79
+
found: 505.56 (10) [M +Na] , 503.54 (14) [M +Na] , 425 (100), 423 (82), 395 (21), 393 (13).
[
((4R*,5R*)-5-{4,5-dimethoxy-2-[(1E,3E)-4-(tributylstannyl)buta-1,3-dienyl]phenyl}-2,2-dimethyl-
,3-dioxolan-4-yl)ethynyl](triethyl)silane (14c) (named "5,6-dimethoxy" for convenience in the
communication)
1
Bu Sn
3
O
O
O
O
SnBu3
11
Pd(PPh ) , PhH, 80°C
MeO
MeO
TES
3
4
MeO
MeO
TES
Br
SnBu3
1
3c
14c
1
6

A solution of compound 13c (2.365 g, 4.912 mmol, 1 equiv), trans-1,2-bis(tributylstannyl)ethylene 11
3.87 g, 6.385 mmol, 1.3 equiv) and Pd(PPh ) (284 mg, 0.245 mmol, 0.05 equiv) in dry degassed
(
3
4
benzene (35 mL) was heated at reflux, under argon, for 4 hours (monitored by TLC). The solvent was
then evaporated under reduced pressure and the crude residue was purified by flash column
chromatography (hexane) using Et N pretreated (2 %) silica gel. The title compound 14c was isolated as
3
a yellowish oil (2.643 g, 3.683 mmol, 75 %).
1
TLC: R 0.29 (ether/hexane 2/8). H NMR (300 MHz, CDCl ): δ 0.63 (q, 6H, J = 7.8), 0.89-1.00 (t, 9H,
f
3
J = 7.8 overlapped with m, 15H), 1.25-1.41 (m, 6H), 1.48-1.60 (m, 6H), 1.62 (s, 3H), 1.63 (s, 3H), 3.90
(
s, 3H), 3.93 (s, 3H), 4.45 (d, 1H, J = 7.5), 5.39 (d, 1H, J = 7.5), 6.39 (d, 1H, J = 18.2), 6.61 (dd, 1H, J =
1
3
1
5, 9.7), 6.70 (dd, 1H, J = 18.2, 9.7), 6.98 (d, 1H, J = 15), 6.99 (s, 1H), 7.02 (s, 1H). C NMR (75
1
2
3
MHz, CDCl ): δ 4.15, 7.39, 9.50 ( J
= 336), 13.66, 26.15, 26.90, 27.29 ( J
= 53), 29.11 ( J
=
3
C-Sn
C-Sn
C-Sn
2
1
1
0), 55.74, 55.85, 73.15, 79.95, 90.08, 102.88, 108.36, 109.17, 110.42, 126.90, 127.51, 129.31, 133.09,
1
35.15 ( J = 376), 146.92, 148.90, 148.90. IR (neat): ν 3086, 2952, 2860, 2174 (C≡C), 1602, 1556,
C-Sn
510, 1463, 1238, 1052, 868, 739. MS (ESI, positive ion 135 eV) (intensity): calc'd for
+
+
(C H O SiSnNa ) 741.43; found: 741.42 (100) [M+Na] .
37 62 4
tributyl((1E,3E)-4-{2-[(4R*,5R*)-5-ethynyl-2,2-dimethyl-1,3-dioxolan-4-yl]-4,5-dimethoxy
phenyl}buta-1,3-dienyl)stannane (15c) (named "5,6-dimethoxy" for convenience in the
communication)
O
O
O
O
NH F
4
MeO
MeO
TES
MeO
MeO
H
SnBu3
SnBu3
1
4c
15c
To a solution of the protected alcyne 14c (0.983 g, 1.37 mmol, 1 equiv) in freshly distilled CH Cl (7
2
2
mL) was added a solution of NH F in water (1.7 mL, 45 %) and n-Bu NHSO (0.093 g, 0.274 mmol, 0.2
4
4
4
equiv). The mixture was stirred at r.t. and monitored by TLC until starting material disappearance (1 h).
The mixture was then poured in water (5 mL) and extracted with CH Cl (2 x 10 mL) and Et O (10 mL).
2
2
2
The combined organic layer was washed with brine, dried over Na SO and concentrated in vacuo. The
2
4
residue was purified by flash column chromatography (hexane) using Et N pretreated (2 %) silica gel
3
and gave the deprotected compound 15c as a yellowish oil (0.826 g, 1.37 mmol, 100 %).
1
TLC: R 0.11 (ether/hexane 1/9). H NMR (200 MHz, CDCl ): δ 0.87-0.98 (m, 15H), 1.27-1.39 (m, 6H),
f
3
1
1
9
.46-1.58 (m, 6H), 1.63 (s, 6H), 2.56 (d, 1H, J = 1.5), 3.90 (s, 3H), 3.92 (s, 3H), 4.42 (dd, 1H, J = 7.6,
.5), 5.42 (d, 1H, J = 7.6), 6.38 (d, 1H, J = 18.9), 6.61 (dd, 1H, J = 15.6, 9.9), 6.69 (dd, 1H, J = 18.9,
1
3
1
.9), 6.96 (d, 1H, J = 15.6), 7.01 (s, 1H), 7.02 (s, 1H). C NMR (50 MHz, CDCl ): δ 9.57 ( J = 336),
3
C-Sn
1
7

2
3
1
1
3
3.70, 26.12, 26,86, 27.81 ( J
= 55), 29.11 ( J
= 20), 55.81, 55.86, 72.21, 75.55, 79.79, 80.49,
C-Sn
C-Sn
08.34, 108.99, 110.61, 126.66, 127.73, 129.11, 132.74, 135.89, 147.00, 148.89, 148.92. IR (CHCl ): ν
307, 2958, 2860, 1601, 1554, 1456, 1378, 1273, 1212, 1114, 1049, 1002, 908, 737. MS (ESI, positive
3
+
+
ion 135 eV) (intensity): calc'd for (C H O SnNa ) 627.34; found: 627.25 (100) [M+Na] .
31 48 4
(
5Z)-5-[3-((4R*,5R*)-5-{4,5-dimethoxy-2-[(1E,3E)-4-(tributylstannyl)buta-1,3-dienyl]phenyl}-2,2-
dimethyl-1,3-dioxolan-4-yl)prop-2-ynylidene]cyclopent-1-en-1-yl trifluoromethanesulfonate (4c)
named "5,6-dimethoxy" for convenience in the communication)
(
O
O
1
)
MeO
TMS
H
O
O
OMe
OMe
OTf
OTf
MeO
SnBu
3
1
5c
Pd(PPh ) Cl , CuI,
PhH/ i -Pr NH, r.t.
3
2
2
2
OTf
2
)
(0,3 eq.)
7
Bu Sn
4c
3
To a solution of the deprotected alkyne 15c (0.687 g, 1.138 mmol, 1.1 equiv) and the bis-enoltriflate 7
(
0.389 g, 1.035 mmol, 1 equiv) in dry benzene (9 mL) was added the catalyst Pd(PPh ) Cl (0.029 g,
3
2
2
0
.0414 mmol, 0.04 equiv), CuI (0.029 g, 0.155 mmol, 0.15 equiv) and anhydrous i-Pr NH (3 mL). The
2
mixture was then carefully degassed and placed under argon. Reaction at r.t., was monitored by TLC
until the disappearance of the bis-enoltriflate 7 (around 2 h). To elimitate the minor endo-enoltriflate
product 16c (versus the exo 4c), TMS-acetylene was added (0.040 mL, d = 0.695, 0.310 mmol, 0.3
2
equiv) in a kinetic differentiation reaction . Thus the reaction mixture was stirred for an additional 2 h,
then quenched by addition of saturated aqueous NH Cl (5 mL) and extracted with Et O. The extract was
4
2
washed with water, brine, dried over MgSO and concentrated under reduced pressure. The crude
4
product was purified by flash column chromatography (ether/hexane 0/100 to 10/90) using Et N
3
pretreated (2 %) silica gel and gave the title product 4c as a yellow oil (0.774 g, 0.933 mmol, 90 %).
1
TLC: R 0.37 (ether/hexane 3/7). H NMR (200 MHz, CDCl ): δ 0.88-0.97 (m, 15H), 1.22-1.39 (m,
f
3
6
4
6
1
2
1
1
1
H), 1.49-1.59 (m, 6H), 1.61 (s, 6H), 2.50-2.56 (m, 2H), 2.69-2.75 (m, 2H), 3.90 (s, 3H), 3.92 (s, 3H),
.64 (dd, 1H, J = 7.7, 2.4), 5.41 (d, 1H, J = 7.7), 5.47 (s br, 1H), 6.21 (s br, 1H), 6.34 (d, 1H, J = 18.1),
.59 (dd, 1H, J = 13.8, 9.8), 6.70 (dd, 1H, J = 18.1, 9.8), 6.98 (d, 1H, J = 13.8), 7.02 (s, 1H), 7.03 (s,
1
3
1
2
H). C NMR (50 MHz, CDCl ): δ 9.53 ( J = 337), 13.69, 26.26, 26.99, 26.99, 27.28 ( J
= 55),
3
C-Sn
C-Sn
3
8.91, 29.11 ( J
= 21), 55.78, 55.86, 73.05, 79.54, 83.03, 91.25, 98.45, 108.43, 109.40, 110.13,
C-Sn
18.53 (JC-F = 321), 126.84, 128.17, 129.31, 129.45, 132.47, 134.15, 147.33, 147.34, 148.80, 148.85,
48.99. IR (neat): ν 2958, 2927, 2871, 2854, 2254 (C≡C),1604, 1511, 1427, 1380, 1213, 1142, 1050,
+
002, 910, 867, 735. MS (ESI, positive ion 135 eV) (intensity): calc'd for (C H F O SSnNa ) 853.3;
3
8 53 3 7
+
found: 853.3 (100) [M+Na] .
1
8

(3aR*,7bR*,9aS*,13cR*)-5,6-dimethoxy-2,2-dimethyl-3a,7b,9a,11,12,13c-
hexahydropentaleno[1',2':7,8]phenanthro[9,10-d][1,3]dioxole (1c)
and
(3aR*,13cR*)-5,6-dimethoxy-2,2-dimethyl-3a,11,12,13c-
tetrahydropentaleno[1',2':7,8]phenanthro[9,10-d][1,3]dioxole (18c)
O
OMe
O
OMe
OMe
O
O
OMe
OMe
O
O
Pd(CH CN) Cl
2
OMe
+
3
2
H
LiCl, DMF, rt
OTf
H
Bu Sn
3
4
c
1c
18c
rt
A solution of the enoltriflate 4c (0.751 g, 0.9052 mmol, 1 equiv), Pd(CH CN) Cl (0.012 g, 0.0452
3
2
2
mmol, 0.05 equiv) and LiCl (0.077 g, 1.810 mmol, 2 equiv) in anhydrous DMF (90 mL) was carefully
degassed and placed under argon. The mixture was stirred at r.t. for 3 h (monitored by TLC) and, as the
reaction was completed, the DMF was reduced in vacuo. The crude was directly purified by flash
column chromatography (ether/hexane 5/95) using Et N pretreated (2 %) silica gel without any aqueous
3
work-up. The cyclized products 1c and 18c were obtained as a yellow oil (0.247 g, 0.632 mmol, 70 %).
We noted that compound 1c smoothly aromatized in 18c.
Data for 1c:
1
TLC: R 0.42 (ether/hexane 5/5). H NMR (200 MHz, CDCl ): δ 1.62 (s, 6H), 2.56 (m, 2H), 2.85 (m,
f
3
2
4
2
5
1
3
H), 3.66-3.71 (m, 1H), 3.89 (s, 3H), 3.92 (s, 3H), 4.04-4.12 (d, 1H, J = 9.3 overlapped with m, 1H),
.68 (d, 1H, J = 9.3), 5.64 (s br, 1H), 6.30 (d, 1H, J = 1.7 overlapped with m, 1H), 6.54 (dt, 1H, J = 9.4,
1
3
), 6.99 (s, 1H), 7.03 (s, 1H). C NMR (50 MHz, CDCl ): δ 23.61, 23.61, 27.40, 27,40, 39.22, 40.94,
3
6.11, 56.35, 77.77, 80.53, 106.05, 109.27, 112.86, 115.58, 117.16, 118.43, 120.31, 126.87, 127.38,
+
28.92, 146.53, 147.79, 150.23, 153.79, 162.80. MS (EI, 70 eV) (intensity): calc'd for (C H O )
2
5 26 4
+
+
90.1; found: 390.1 (68) [M] , 332.2 (100) [M-(CH ) CO] , 330.1 (52), 315.1 (43), 304.2 (45), 301.1
3
2
(37), 113.1 (16).
Data for 18c:
1
TLC: R 0.36 (ether/hexane 1/9). H NMR (200 MHz, CDCl ): δ 1.62 (s, 3H), 1.64 (s, 3H), 2.78 (m,
f
3
2
H), 3.12 (m, 2H), 3.96 (s, 3H), 3.96 (s, 3H), 4.78 (syst AB, 2H, JAB = 11.0, ∆ν = 17.1 Hz), 6.77 (t, 1H,
13
J = 2.3), 6.81 (sbr, 1H), 7.01 (s br, 1H), 7.47 (syst AB, 2H, JAB = 7.8, ∆ν = 39.7 Hz), 7.99 (s, 1H). C
NMR (50 MHz, CDCl ): δ 23.26, 27.30, 27.34, 39.40, 56.08, 56.17, 79.21, 80.56, 106.03, 108.73,
3
1
1
1
13.39, 114.92, 118.92, 121.14, 125.26, 125.91, 128.07, 129.33, 132.60, 133.81, 146.40, 148.30, 148.90,
49.29, 155.48. IR (CHCl ): ν 3013, 2944, 2853, 1669, 1606, 1504, 1458, 1401, 1373, 1213, 1151,
3
+
+
082, 997, 769. MS (EI, 70 eV) (intensity): calc'd for (C H O ) 388.1; found: 388.1 (65) [M] , 341.3
2
5 24 4
1
9

+
+
+
(
1) [M-CH OCH ] , 330.1 (56) [M-OC(CH ) ] , 322.1 (25) [M-(CH ) -H O] , 269.0 (100) [M+H-
3
2
3 2
3 2
2
+
OC(CH ) -2OCH ] , 265.0 (54), 264.1 (55), 194.9 (49), 57.2 (34).
3
2
3
(
Z)-{2-[((4R*,5R*)-2,2-dimethyl-5-{2-[(1E,3E)-4-(tributylstannyl)buta-1,3-dienyl}phenyl-1,3-
dioxolan-4-yl)ethynyl]cyclohex-2-en-1-ylidene}methyl trifluoromethanesulfonate (5)
O
O
H
OTf OTf
Bu Sn
3
SnBu3
O
15
OTf
O
Pd(PPh ) Cl , CuI,
3
2
2
PhH/ i- Pr NH, r.t.
2
8
5
To a solution of the deprotected alkyne 15 (0.598 g, 1.1 mmol, 1.1 equiv) and the bis-enoltriflate 8
0.390 g, 1 mmol, 1 equiv) in dry benzene (15 mL) was added the catalyst Pd(PPh ) Cl (0.0281 g, 0.04
(
3
2
2
mmol, 0.04 equiv), CuI (0.019 g, 0.1 mmol, 0.1 equiv) and anhydrous diisopropylamine (5 mL). The
mixture was then carefully degassed and placed under argon. Reaction at r.t., was monitored by TLC
until the disappearance of the bis-enoltriflate 8 (around 2 h). The reaction mixture was then quenched by
addition of saturated aqueous NH Cl (10 mL) and extracted with Et O. The extract was washed with
4
2
water, brine, dried over Na SO and concentrated under reduced pressure. The crude product was
2
4
purified by flash column chromatography (ether/hexane 5/95) using Et N pretreated (2 %) silica gel and
3
gave the title product 5 as a yellow oil (0.564 g, 0.72 mmol, 72 %).
1
TLC: R 0.49 (ether/hexane 2/8). H NMR (300 MHz, CDCl ): δ 0.89-0.97 (m, 15H), 1.28-1.40 (m,
f
3
6
1
=
H), 1.48-1.59 (m, 6H), 1.61 (s, 6H), 1.71-1.79 (m, 2H), 2.18-2.22 (m, 2H), 2.25-2.30 (m, 2H), 4.65 (d,
H, J = 7.8), 5.41 (d, 1H, J = 7.8), 6.39 (d, 1H, J = 17.5), 6.39 (s br, 1H), 6.40 (s br, 1H), 6.68 (dd, 1H, J
13
14.7, 10), 6.70 (dd, 1H, J = 17.5, 10), 7.05 (d, 1H, J = 14.7), 7.26-7.30 (m, 2H), 7.51-7.55 (m, 2H). C
1
2
NMR (50 MHz, CDCl ): δ 9.52 ( J = 335), 13.68, 21.68, 26.29, 26.58, 26.94, 27.29 ( JC-Sn= 54),
3
C-Sn
3
2
1
7.33, 29.12 ( JC-Sn= 21), 72.82, 79.81, 84.94, 85.00, 110.29, 115.39, 118.59 (q, JC-F = 319), 123.70,
26.00, 126.82, 127.67, 128.24, 128.29, 129.22, 133.94, 134.32, 135.54, 136.64, 144.62, 147.09. IR
(
CHCl ): ν 2957, 2929, 2872, 2854, 2253 (C≡C), 1794, 1653, 1556, 1424, 1382, 1246, 1218, 1140,
3
+
+
1
056, 1025, 1002, 908, 843, 734. MS (EI, 70 eV): m/z (%) 783 (1) [M] , 650 (7) [(M-SO CF )] , 471
2
3
+
(80), 494 (2) [(M-Bu Sn)] , 336 (100).
3
(3aR*,7bR*,9aS*,14dR*)-2,2-dimethyl-7b,9a,11,12,13,14d-hexahydro-3aH-
indeno[1',2':1,2]phenanthro[9,10-d][1,3]dioxole (2)
2
0

and
3aR*,14dR*)-2,2-dimethyl-11,12,13,14d-tetrahydro-3aH-indeno[1',2':1,2]phenanthro[9,10-
d][1,3]dioxole (2arom)
(
H
H
Bu Sn
3
Pd(CH CN) Cl
2
3
2
O
OTf
+
LiCl, DMF, r.t.
O
O
O
O
O
5
2
2arom
r.t.
A solution of the enoltriflate 5 (0.500 g, 0.64 mmol, 1 equiv), Pd(CH CN) Cl (0.0083 g, 0.032 mmol,
3
2
2
0
.05 equiv) and LiCl (0.054 g, 1.28 mmol, 2 equiv) in anhydrous DMF (15 mL) was carefully degassed
and placed under argon. The mixture was stirred at r.t. until the disapearance of the starting material
monitored by TLC, 4 h). Then the reaction was quenched with a saturated aqueous solution of NH Cl (5
(
4
mL) and extracted with Et O (3 x 10mL). The combined organic extracts were washed with brine, dried
2
over Na SO and concentrated in vacuo. The residue was purified by flash column chromatography
2
4
(
ether/hexane 5/95) using Et N pretreated (2 %) silica gel. The cyclized products 2 and 2arom were
3
obtained as yellow oils (0.448 mg, 1.300 mmol, 51 % global yield).
Data for 2:
1
TLC: R 0.56 (ether/hexane 2/8). H NMR (300 MHz, CDCl ): δ 1.49-1.59 (m, 2H), 1.64 (s, 3H), 1.69
f
3
(
(
s, 3H), 1.81-1.97 (m, 2H), 2.34-2.66 (m, 2H), 3.86 (td, 1H, J = 10.9, 2.8), 4.09 (d br, 1H, J = 9.4), 4.18
d br, 1H, J = 10.9), 4.94 (dd, 1H, J = 9.1, 0.8), 5.73 (s br, 1H), 6.24 (dt, 1H, J = 9.7, 2.7), 6.50 (dt, 1H, J
=
9.7, 2.7), 6.74 (t br, 1H, J = 4.7), 7.30-7.32 (m, 1H), 7.41-7.47 (m, 1H), 7.54-7.57 (m, 1H), 7.73-7.76
1
3
(
m, 1H). C NMR (75 MHz, CDCl ): δ 21.95, 25.92, 26.10, 30.31, 30.31, 39.72, 47.19, 77.58, 79.00,
3
1
1
12.14, 121.24, 123.39, 124.32, 125.50, 126.43, 128.79, 129.22, 130.85, 132.33, 135.57, 135.78, 136.10,
+
+
38.31, 141.81. MS (EI, 70 eV) (intensity): calc'd for (C H O ) 344.1; found 344.1 (1) [M] , 270.1
2
4 24 2
+
(
100) [M-(CH ) CO ] .
3
2
2
Data for 2arom:
TLC: R 0.56 (ether/hexane 2/8). H NMR (300 MHz, CDCl ): δ 1.66 (s, 3H), 1.68 (s, 3H), 1.83-1.97
1
f
3
(
m, 2H), 2.51-2.61 (m, 2H), 2.75 (td, 2H, J = 6.2, 1.4), 4.90 (syst AB, 2H, JAB = 10.6, ∆ν = 31.3 Hz),
6
.46 (d, 1H, J = 1.3), 7.24 (d, 1H, J = 7.8), 7.36 (tt, 2H, J = 8.7, 1.6), 7.51 (td br, 1H, J = 6.8, 1.2), 7.63
1
3
(
d, 1H, J = 7.8), 7.68 (d br, 1H, J = 7.5), 7.90 (td, 1H, J = 4.7, 1.6 Hz). C NMR (75 MHz, CDCl ): δ
3
2
1
3.98, 25.68, 27.23, 27.37, 27.37, 79.36, 80.12, 112.41, 119.19, 122.10, 122.64, 124.45, 124.73, 127.02,
27.67, 128.42, 129.74, 130.65, 134.06, 134.33, 138.69, 139.09, 141.04, 144.88. IR (CHCl ): ν 3019,
3
2
1

2
990, 2850, 1604, 1522, 1478, 1415, 1376, 1215, 1161, 1120, 758. MS (EI, 70 eV) (intensity): calc'd for
+
+
+
(C H O ) 344.1; found 344.1 (1) [M] , 270.1 (100) [M-(CH ) CO ] .
24 22 2
3 2
2
(2Z)-2-(hydroxymethylene)cycloheptanone (B)
H
O
O
O
1
) NaH, 0°C
2
) HCO Et, 0°C to rt
2
B
To a stirred solution of sodium hydride (60 % NaH in oil, 13.907 g, 347.68 mmol, 1.3 equiv) in dry THF
250 mL) at 0°C and under argon was first slowly added cycloheptanone (31.54 mL, d = 0.951, 267.5
(
mmol, 1 equiv) and then a solution of ethyl formate (32.7 mL, d = 0.917, 401.2 mmol, 1.5 equiv) in dry
THF (30 mL). The mixture was stirred for 3 h, while the temperature was allowed to warm up to r.t..
The obtained mudy reaction mixture is poured carefully into ice/water (400 g/400 mL). The aqueous
layer was extracted with ether (1 x 50 mL) and then neutralised with solid sodium dihydrogen phosphate
(
NaH PO .H O, 150 g) and acidified with concentrated hydrochloric acid (20 mL, 36 %). The solution
2
4
2
was extracted with ether (6 x 300 mL) and the combined organic extract was washed with brine and
dried over MgSO . After evaporation of the solvents in vacuo, the residue was purified by silica gel flash
4
column chromatography (ether/hexane 3/97) to give the title compound B as a pinkish oil (33.20 g, 237
mmol, 89 %).
1
TLC: R 0.13 (ether/hexane 3/97). H NMR (300 MHz, CDCl ): δ 1.57-1.62 (m, 2H), 1.67-1.75 (m, 4H),
2
f
3
1
3
.24 (t, 2H, J = 5.6), 2.52 (t, 2H, J = 5.1), 7.62 (d, 1H, J = 8.7), 14.67 (d, 1H, J = 8.7). C NMR (75
MHz, CDCl ): δ 24.47, 28.41, 29.66, 31.52, 41.83, 114.45, 170.70, 204.02. IR (CHCl ): ν 2977, 2929,
3
3
2
858, 2243, 1638, 1582, 1450, 1383, 1264, 1222, 1112, 909, 734. MS (ESI, positive ion 130 eV)
+
+
(
[
intensity): calc'd for (C H O Na ) 163.0735; found 163.0751 (50) [M+Na] , 153 (70), 141.1482 (100)
8 12 2
+
M+H] .
(
Z)-(2-oxocycloheptylidene)methyl trifluoromethanesulfonate (C)
H
O
O
TfO
O
1) n-BuLi, THF, -78°C
2
) Tf O, -78°C
2
B
C
A refrigerated solution (-78°C) of t-butyllithium (1.54 M in pentane, 92.7 mL, 143 mmol, 1 equiv) was
added in a dried round-bottom flask under argon containing compound B (20 g, 143 mmol, 1 equiv) in
2
2

freshly distilled THF (560 mL) at -78 °C. The reaction was stirred 15 min at this temperature and a
refrigerated solution (-78°C) of trifluoromethansulfonic anhydride (28.94 mL, d = 1.677, 172 mmol, 1.2
equiv) was added dropwise. The reaction was stirred for 15 min at this temperature and then quenched
by addition of a saturated solution of NaHCO (40 mL) and brine (80 mL). The organic medium was
3
washed with water (200 mL) and the mixture was extracted with Et O. The combined organic layers
2
were dried over MgSO and concentrated in vacuo. The crude product was purified by Et N pretreated
4
3
silica gel flash column chromatography (hexane) to afford the title compound C as a yellowish oil
20.42 g, 75 mmol, 53 %).
(
1
TLC: R 0.11 (ether/hexane 1/9). H NMR (300 MHz, CDCl ): δ 1.75 (s br, 6H), 2.34 (m, 2H), 2.59 (m,
f
3
1
3
2
3
1
2
H), 6.60 (s br, 1H). C NMR (50 MHz, CDCl ): δ 24.41, 29.11, 30.29, 30.51, 43.81, 118.42 (q, J
20.80), 132.29, 135.18, 201.08. IR (CHCl ): ν 3093, 2935, 2860, 2359, 1702, 1626, 1426, 1248, 1212,
142, 1004, 942, 895, 838, 618. MS (ESI, positive ion 130 eV) (intensity): calc'd for (C H F O SNa )
=
3
C-F
3
+
9
11 3 4
+
+
95.0228; found 295.0327 (100) [M+Na] , 244.1832 (3), 203.1480 (2) [M-CF ] , 162.0645 (1) [M-
3
+
SO CF +Na] , 153 (5).
2
3
(
(
Z)-(2-{[(trifluoromethyl)sulfonyl]oxy}cyclohept-2-en-1-ylidene)methyl trifluoromethanesulfonate
9)
OTf
TfO
O
1
) LiHMDS, THF, -78°C
) Tf O, -78°C
OTf
2
2
C
9
A refrigerated solution (-78°C) of n-butyllithium (1.46 M in hexane, 5.53 mL, 8.081 mmol, 1.1 equiv)
was added to a dried round-bottom flask under argon containing hexamethyldisilylazane (1.86 mL, d =
0
.765, 8.816 mmol, 1.2 equiv) in freshly distilled THF (30 mL) at -78 °C. The reaction was stirred 15
min at this temperature and a refrigerated solution (-78°C) of compound C (2 g, 7.346 mmol, 1 equiv) in
freshly distilled THF (10 mL) was added. The reaction was stirred 15 min at this temperature and a
refrigerated solution (-78°C) of trifluoromethansulfonic anhydride (1.23 mL, d = 1.677, 7.346 mmol, 1
equiv) was added dropwise. The reaction was then quenched by addition of a saturated solution of
NaHCO (15 mL) and brine (30 mL). After extraction with Et O, the combined organic layers were dried
3
2
over MgSO and concentrated in vacuo. The crude product was purified by silica gel flash column
4
chromatography (ether/hexane 3/97) to afford the title compound 9 as a colorless oil (1.13 g, 2.795
mmol, 38 %).
1
TLC: R 0.20 (ether/hexane 10/90). H NMR (200 MHz, CDCl ): δ 1.65-1.88 (m, 4H), 2.23-2.38 (m,
f
3
1
3
4
1
H), 6.14 (t, 1H, J = 6.23), 6.65 (s br, 1H). C NMR (50 MHz, CDCl ): δ 24.90, 25.51, 29.45, 29.53,
18.49 (2q, JC-F = 320.8), 124.84, 128.56, 133.73, 143.14. IR (CHCl ): ν 3102, 2940, 2864, 1688, 1633,
3
3
2
3

1
431, 1249, 1214, 1141, 1068, 1031, 993, 882, 840, 612. MS (ESI, positive ion 130 eV): m/z (%) 385
+
+
(50) [M-F] , 271 (3) [M+H-SO CF ] .
2
3
(
Z)-{2-[((4R*,5R*)-2,2-dimethyl-5-{2-[(1E,3E)-4-(tributylstannyl)buta-1,3-dienyl]penyl}-1,3-
dioxolan-4-yl)ethynyl]cyclohept-2-en-1-ylidene}methyl trifluoromethanesulfonate (6)
O
O
H
OTf
OTf
Bu Sn
3
SnBu
3
1
5
O
OTf
O
Pd(PPh ) Cl , CuI,
3
2
2
2
PhH/ i-Pr NH, r.t.
9
6
To a solution of the deprotected alkyne 15 (1.00 g, 1.84 mmol, 1.1 equiv) and the bis-enoltriflate 9
(
0.676 g, 1.67 mmol, 1 equiv) in dry benzene (23 mL) was added the catalyst Pd(PPh ) Cl (0.047 g,
3
2
2
0
.067 mmol, 0.04 equiv), CuI (0.032 g, 0.167 mmol, 0.1 equiv) and anhydrous diisopropylamine (6.7
mL). The mixture was then carefully degassed and placed under argon. Reaction at r.t., was monitored
by TLC until the disappearance of the bis-enoltriflate 9 (around 45 min.). The reaction mixture was then
quenched by addition of a saturated solution of NH Cl (7 mL) and extracted with Et O. The extract was
4
2
washed with brine, dried over MgSO and concentrated under reduced pressure. The crude product was
4
purified by Et N pretreated silica gel flash column chromatography (ether/hexane 5/95) to afford the title
3
compound 6 as a yellow oil (0.88 g, 0.11 mmol, 66 %).
1
TLC: R 0.19 (ether/hexane 5/95). H NMR (200 MHz, CDCl ): δ 0.88-0.99 (m, 15H), 1.26-1.40 (m,
f
3
6
H), 1.47-1.61 (m, 6H), 1.61 (s, 6H), 1.58-1.83 (m, 4H), 2.19-2.29 (m, 4H), 4.61 (d, 1H, J = 7.7), 5.38
(
(
d, 1H, J = 7.7), 6.40 (d, 1H, J = 17.8), 6.41 (s br, 1H), 6.44 (s br, 1H), 6.69 (dd, 1H, J = 14.8, 9.3), 6.71
1
3
dd, 1H, J = 17.8, 9.3), 7.04 (d, 1H, J = 14.8), 7.26-7.30 (m, 2H), 7.49-7.56 (m, 2H). C NMR (50
1
2
3
MHz, CDCl ): δ 9.51 ( J = 336), 13.66, 24.88, 26.24, 26.89, 27.28 ( J = 55), 29.08 ( J = 18),
3
C-Sn
C-Sn
C-Sn
2
1
2
9.29, 30.38, 30.72, 72.91, 80.13, 83.55, 85.91, 110.32, 118.52 (q, J = 319), 119.50, 126.04, 126.89,
C-F
27.69, 128.13, 128.33, 130.02, 131.65, 133.81, 134.42, 135.68, 136.63, 144.80, 147.08. IR (CHCl ):
3
978, 2933, 2871, 2810, 2243 (C≡C), 1654, 1560, 1446, 1383, 1351, 1246, 1150, 1113, 909, 844, 734.
+
MS (ESI, positive ion 130 eV) (intensity): calc'd for (C H F O SSnNa ) 821.34; found: 821.33 (25)
3
8 53 3 5
+
+
+
[M+Na] , 804.56 [M+Na-CH ] , 663.33 (18), 531.15 (13) [M+H-SnBu ] .
3
3
(3aR*,7bR*,9aS*,15dR*)-2,2-dimethyl-3a,7b,9a,11,12,13,14,15d-
octahydroazuleno[1',2':1,2]phenanthro[9,10-d][1,3]dioxole(1:1) (3)
and
2
4

(3aR*,15dR*)-2,2-dimethyl-3a,11,12,13,14,15d-hexahydroazuleno[1',2':1,2]phenanthro[9,10-
d][1,3]dioxole (3arom)
H
H
Bu Sn
3
Pd(CH CN) Cl
2
3
2
O
+
OTf
LiCl, DMF, rt
O
O
O
O
O
6
3
3arom
rt
A solution of the enoltriflate 6 (0.500 g, 0.627 mmol, 1 equiv), Pd(CH CN) Cl (0.008 g, 0.031 mmol,
3
2
2
0
.05 equiv) and LiCl (0.053 g, 1.254 mmol, 2 equiv) in anhydrous DMF (15 mL) was carefully degassed
and placed under argon. The mixture was stirred at r.t. until the disapearance of the starting material
monitored by TLC, 1 h). Then the reaction was quenched with water (5 mL) and extracted with Et O (3
(
2
x 10mL). The combined organic extracts were dried over MgSO and concentrated in vacuo. The residue
4
was purified by Et N pretreated silica gel flash column chromatography (hexane) to afford the cyclized
3
and inseparable products 3 and 3arom. (which resulted from the aromatisation of 3) as a yellow oil for a
global yield around 50 %. We noticed that after 5 days the isolated mixture only contained 3arom.
Data for 3:
1
TLC: R 0.54 (ether/hexane 2/8). H NMR (300 MHz, CDCl ): δ 1.70 (s, 3H), 1.71 (s, 3H), 1.59-1.75
f
3
(
m, 2H), 1.87-1.91 (m, 2H), 2.58-2.66 (m, 2H), 2.75-2.95 (m, 2H), 3.90 (d br, 1H, J = 10.6), 4.06 (d br,
1
H, J = 9), 4.20 (d br, 1H, J = 11.2), 4.97 (d, 1H, J = 8.7), 5.82 (s br, 1H), 6.20 (d br, 1H, J = 10), 6.44
1
3
(
(
d br, 1H, J = 10), 6.89 (t br, 1H, J = 5.9), 7.40 (s br, 1H), 7.52 (m, 2H), 7.66 (d, 1H, J = 7.5). C NMR
75 MHz, CDCl ): δ 25.97, 26.91, 28.24, 28.28, 30.25, 30.48, 39.31, 46.30, 77.48, 78.56, 111.70,
3
1
1
19.00, 120.88, 124.20, 127.32, 128.55, 129.66, 130.20, 135.19, 135.67, 136.90, 139.00, 139.71, 142.07,
+
+
46.42. MS (EI, 70 eV) (intensity): calc'd for (C H O ) 358.2; found: 358.5 (5) [M] , 300.5 (5) [M-
2
5 26 2
+
+
(CH ) CO] , 284.4 (3) [M-(CH ) CO ] , 272.4 (2), 254.3 (13), 241.3 (28).
3
2
3 2
2
Data for 3arom.:
TLC: R 0.54 (ether/hexane 2/8). H NMR (200 MHz, CDCl ): δ 1.60-1.78 (m, 2H), 1.62 (s, 3H), 1.66
1
f
3
(
s, 3H), 1.87-1.95 (m, 2H), 1.90-1.99 (m, 2H), 2.50-2.67 (m, 2H), 4.88 (syst AB, 2H, JAB = 10.5, ∆ν =
3
7
2
1
2.6 Hz), 6.57 (s br, 1H), 7.22 (d, 1H, J = 7.8), 7.36 (td, 2H, J = 6.7, 1.8), 7.49 (m, 1H), 7.59 (d, 1H, J =
1
3
.8), 7.64 (dd, 1H, J = 7.6, 1.7), 7.76 (td, 1H, J = 5.9, J = 1.5). C NMR (75 MHz, CDCl ): δ 25.71,
3
7.33, 27.33, 27.74, 29.70, 30.65, 79.29, 79.69, 112.11, 119.06, 121.93, 124.08, 124.88, 126.97, 127.12,
27.40, 127.68, 130.26, 133.77, 134.10, 134.49, 141.19, 141.63, 143.53, 145.67. MS (EI, 70 eV): m/z
(
%) 357 [M+H], (11), 356 [M], (57), 298 [(M-(CH ) CO]. IR (CHCl ): ν 3019, 2929, 2855, 1718, 1632,
3
2
3
1
522, 1480, 1418, 1376, 1262, 1216, 1088, 1059, 1028, 758. MS (EI, 70 eV) (intensity): calc'd for
2
5

+
+
+
+
(
C H O ) 356.2; found: 356.3 (56) [M] , 297.8 (100) [M-(CH ) CO] , 282.4 (8) [M-(CH ) CO ] ,
25 24 2
3 2
3 2
2
2
70.4 (21), 252.2 (36), 239.2 (58).
References
1
2
– J. Suffert, J. Org. Chem. 1989, 54, 509-510
– Scheuplein, S.; Harms, K.; Brückner, R.; Suffert, J. Chem. Ber. 1992, 125, 271-278
3
3
– compound preparated following the procedure of A. E. Gies, M. Pfeffer, J. Org. Chem. 1999, 64,
650-3654
2
6