M.K.J. ter Wiel, B.L. Feringa / Tetrahedron 65 (2009) 4332–4339
4337
118.0 (s), 118.1 (d), 118.5 (d), 122.6 (d), 122.9 (d), 124.4 (d), 124.5 (d),
125.3 (d), 125.5 (d), 126.0 (d), 126.3 (d), 126.6 (d), 126.7 (d), 126.8
(d), 126.9 (d), 127.3 (d), 127.4 (d), 127.5 (d), 127.6 (d), 127.67 (d),
127.71 (d), 127.8 (d), 128.46 (s), 128.54 (s), 129.06 (d), 129.3 (d),
129.92 (s), 130.9 (s), 131.4 (s), 133.1 (s), 134.2 (s), 134.6 (s), 135.9 (s),
136.0 (s), 136.3 (s),136.36 (s), 136.44 (s), 136.7 (s),138.6 (s),139.1 (s),
139.2 (s), 139.4 (s), 140.6 (s), 154.09 (s), 154.14 (s). Due to overlap in
the aromatic region of the spectrum only 24 out of 32 signals for
doublets and 22 out of 28 signals for singlets were observed; m/z
(EI, %)¼482 (Mþ, 100); HRMS (EI): calcd for C34H26OS: 482.1704,
found: 482.1697.
washing with small amounts of ether and ethyl acetate (42 mg,
0.09 mmol, 90%); 1H (500 MHz, CDCl3)
0.83 (s, 3H, cis), 1.70 (s, 3H,
d
cis), 1.99 (s, 3H, trans), 2.25 (s, 3H, trans), 2.43–2.54 (m, 1H, cis),
2.56–2.67 (m, 1H, trans), 3.69–3.74 (m, 1H, trans), 3.77–3.82 (m, 1H,
cis), 4.54–4.94 (m, 2H, cis; 2H, trans), 6.32–6.37 (m, 1H, trans),
6.52–6.53 (d, J¼1.8 Hz, 1H, cis), 6.57–6.60 (dd, J¼7.9, 1.3 Hz, 1H,
trans), 6.72–6.75 (dd, J¼8.3, 2.0 Hz, 1H, cis), 6.79–6.81 (d, J¼7.3 Hz,
1H, trans), 6.86–7.69 (m, 14H, cis; 13H, trans); 13C (75 MHz, CDCl3)
d
19.5 (q), 20.6 (q), 20.9 (q), 21.2 (q), 29.1 (t), 29.5 (t), 69.3 (t), 69.6
(t), 116.4 (d), 116.6 (d), 116.9 (d), 117.0 (d), 118.4 (d), 118.8 (d), 118.9
(s), 119.2 (s), 122.3 (s), 122.5 (d), 122.7 (d), 122.8 (s), 122.9 (d), 123.0
(d), 124.50 (d), 124.53 (d), 125.3 (d), 125.6 (s), 125.8 (d), 125.95 (s),
126.03 (s), 126.3 (s), 126.4 (s), 126.6 (2ꢃd), 126.7 (d), 126.8 (d), 126.9
(d), 127.3 (d), 127.4 (d), 127.42 (d), 127.47 (s), 127.6 (d), 127.7 (d),
128.0 (2ꢃd), 128.1 (d), 128.2 (s), 128.3 (d), 128.7 (d), 128.8 (s), 128.9
(d), 129.3 (s), 129.8 (d), 129.9 (d), 135.8 (s), 136.1 (s), 136.2 (s), 136.3
(s), 136.3 (s), 136.6 (s), 140.7 (s), 141.2 (s), 152.7 (s), 153.6 (s), 153.6
(s),154.1 (s),154.2 (s),155.2 (s), one carbon (s) was not observed; m/z
(EI, %)¼466 (Mþ, 100); HRMS (EI) calcd for C34H26O2: 466.1933,
found: 466.1924.
5.2.3. 2-(2,6-Dimethylphenyl)-9-(20,30-dihydro-10H-naphtho-
[2,1-b]thiopyran-10-ylidene)-9H-xanthene (4)
Starting from episulfide 17 (120 mg, 0.23 mmol) using the
standard procedure with p-xylene and copper powder, the alkene 4
(110 mg, 0.23 mmol, 98%) was obtained as a white solid after col-
umn chromatography (SiO2, heptane/ethyl acetate¼50:1); 1H
(300 MHz, CDCl3)
d 0.77 (s, 3H, cis), 1.71 (s, 3H, cis), 2.02 (s, 3H,
trans), 2.00–2.28 (m, 1H, cis; 1H, trans), 2.26 (s, 3H, trans), 3.40–
3.58 (m, 2H, cis; 2H, trans), 3.77–3.87 (m, 1H; cis, 1H, trans), 6.28–
7.67 (m, 16H, cis; 16H, trans); 13C (75 MHz, CDCl3)
d
19.5 (q), 20.6
5.2.6. 2-Bromo-xanthen-9-one (12)
(q), 20.9 (q), 21.2 (q), 29.1 (t), 29.6 (t), 29.9 (t), 30.1 (t), 116.0 (d),
116.2 (d), 116.83 (d), 116.86 (d), 122.3 (d), 123.0 (d), 124.11 (d), 124.17
(d), 124.4 (d), 124.6 (d), 124.8 (s), 125.0 (s), 125.2 (s), 125.77 (d),
125.80 (s), 125.95 (d), 126.07 (d), 126.6 (d), 126.7 (s), 126.8 (d), 127.2
(d), 127.4 (d), 127.5 (d), 127.7 (d), 127.82 (d), 127.85 (d), 128.1 (d),
128.2 (d), 128.3 (d), 128.5 (d), 128.8 (d), 129.2 (d), 130.4 (s), 130.8 (s),
131.5 (s), 132.0 (s), 134.3 (s), 135.3 (s), 135.6 (s), 135.98 (s), 136.0 (s),
136.2 (s), 126.3 (s), 136.6 (s), 140.7 (s), 141.1 (s), 152.4 (s), 153.2 (s),
153.3 (s), 154.7 (s), due to strong overlap in the aromatic region five
(d) and five (s) were not observed; m/z (EI, %)¼482 (Mþ,100); HRMS
(EI) calcd for C34H26OS: 482.1704, found: 482.1695.
This compound was prepared according to a two step literature
procedure18 from which the desired 12 was obtained as a white
solid; mp 149.3–150.5 ꢀC (lit. 150 ꢀC); 1H (300 MHz, CDCl3)
d 7.38–
7.43 (m, 2H), 7.49–7.51 (d, J¼8.4 Hz, 1H), 7.73–7.82 (m, 2H), 8.32–
8.35 (dd, J¼7.8, 1.6 Hz, 1H), 8.45–8.46 (d, J¼2.6 Hz, 1H); 13C
(75 MHz, CDCl3)
d 116.9 (s), 117.9 (d), 119.9 (d), 121.3 (s), 122.9 (s),
124.2 (d), 126.6 (d), 129.0 (d), 135.1 (d), 137.5 (d), 154.7 (s), 155.8 (s),
175.7 (s); m/z (EI, %)¼276 (Mþ, 97), 274 (Mþ, 100), 139 (42); HRMS
(EI): calcd for C13H779BrO2: 273.9629, found: 273.9626.
5.2.7. 2-(2,6-Dimethylphenyl)-9H-xanthen-9-one (14)
A solution of ketone 12 (1.2 g, 4.0 mmol) and Pd(PPh3)4 (190 mg,
0.16 mmol, 4 mol %) in DME (30 ml) was stirred under an argon
atmosphere for 30 min. Then were added 2,6-dimethylphenylbor-
onic acid (0.80 g, 5.2 mmol), Ba(OH)2$8H2O (2.7 g, 8.6 mmol) and
water (30 ml). The resulting mixture was heated overnight at
reflux. Water was added and the reaction mixture was extracted
with ether (3ꢃ50 ml). The combined organic layers were dried over
MgSO4 prior to removal of the solvent under reduced pressure. The
sticky beige solid obtained was then purified by column chromato-
graphy (SiO2, heptane/ethyl acetate¼16:1, Rf¼0.5) providing ketone
14 as a white solid (0.93 g, 3.1 mmol, 78%, mp 133.0–134.2 ꢀC); 1H
5.2.4. 2-(2,6-Dimethylphenyl)-9-(70-methyl-20,30-dihydro-40-
(10H)-phenanthren-40-ylidene)-9H-xanthene (5)
Starting from episulfide 18 (120 mg, 0.24 mmol) using the
standard procedure with p-xylene and copper powder, the alkene 5
(100 mg, 0.21 mmol, 89%) was obtained as a white solid after col-
umn chromatography (SiO2, heptane/ethyl acetate¼50:1); 1H
(300 MHz, CDCl3)
d 0.79 (s, 3H, cis), 1.72 (s, 3H, cis), 1.85–2.39 (m,
3H, cis; 3H, trans), 2.06 (s, 3H, trans), 2.29 (s, 3H, trans), 2.35 (s, 3H,
trans), 2.39 (s, 3H, cis), 3.00–3.10 (m, 2H, cis; 2H, trans), 3.54–3.58
(m, 1H, cis; 1H, trans), 6.26–6.27 (d, J¼2.0 Hz,1H, cis), 6.33–6.35 (m,
2H, trans), 6.69–6.71 (dd, J¼8.3, 2.0 Hz, 1H), 6.81–6.82 (d, J¼7.8 Hz,
1H), 6.87–7.48 (m, 10H, cis; 12H, trans), 7.57–7.59 (d, J¼8.3 Hz, 1H,
cis), 7.65–7.67 (d, J¼8.3 Hz, 1H), 7.69–7.71 (d, J¼7.3 Hz, 1H); 13C
(300 MHz, CDCl3)
d
2.05 (s, 6H), 7.13–7.78 (m, 8H), 8.17 (d, J¼1.8 Hz,
1H), 8.36–8.39 (dd, J¼7.9,1.3 Hz,1H); 13C (75 MHz, CDCl3)
d 20.7 (q),
117.7 (d), 118.0 (d), 121.6 (s), 123.7 (d), 126.4 (d), 126.6 (d), 127.3 (d),
134.6 (d), 135.77 (s), 135.78 (d), 136.7 (s), 139.8 (s), 154.8 (s), 155.9
(s), 176.9 (s), one carbon (s) was not observed due to overlap in the
spectrum; m/z (EI, %)¼300 (Mþ, 100), 299 (62); HRMS (EI) calcd for
C21H16O2: 300.1150, found: 300.1140. Ele. Anal., calcd (%): C, 83.98;
H, 5.37. Found (%): C, 83.82; H, 5.44.
(125 MHz, CDCl3)
d 19.1 (q), 20.6 (q), 21.0 (q), 21.1 (q), 21.2 (q), 21.4
(q), 21.7 (t), 22.1 (t), 28.4 (t), 28.5 (t), 28.6 (t), 29.0 (t), 116.1 (d), 116.3
(d), 116.7 (d), 122.3 (d), 122.9 (d), 123.1 (s), 124.9 (d), 125.0 (d), 125.2
(s), 125.5 (s), 125.6 (s), 126.0 (s), 126.48 (d), 126.51 (d), 126.54 (d),
126.7 (d), 126.8 (d), 126.9 (d), 127.1 (d), 127.3 (d), 127.4 (d), 127.5 (d),
127.6 (d), 127.7 (d), 127.8 (d), 127.9 (d), 128.3 (d), 128.7 (d), 132.4 (s),
132.8 (s), 133.5 (s), 133.7 (s), 133.8 (s), 134.0 (s), 135.7 (s), 136.2 (s),
136.4 (s), 136.5 (s), 136.6 (s), 137.1 (s), 137.5 (s), 141.0 (s), 141.4 (s),
152.6 (s), 153.4 (s), 153.5 (s), 155.0 (s), due to strong overlap in the
aromatic region seven (d) and six (s) were not observed; m/z (EI,
%)¼478 (Mþ, 100); HRMS (EI) calcd for C36H30O: 478.2297, found:
478.2298.
5.2.8. 2-(2,6-Dimethylphenyl)-9H-xanthene-9-thione (11)
Ketone 14 (0.82 g, 2.70 mmol) was heated at reflux overnight in
a suspension of P4S10 (2.0 g, 4.5 mmol) in toluene (25 ml). The sus-
pension was then filtered and the residues washed with CH2Cl2. The
organic volatiles were removed under reduced pressure yielding
a brownish solid, which was purified by column chromatography
(SiO2, heptane/ethyl acetate¼50:1, Rf¼0.6)giving the pure thioketone
11 as tiny green needles (0.72 g, 2.28 mmol, 84%, mp 109.7–
5.2.5. 2-(2,6-Dimethylphenyl)-9-(20,30-dihydro-10H-naphtho[2,1-
b]pyran-10-ylidene)-9H-xanthene (6)
110.7 ꢀC); 1H (300 MHz, CDCl3)
d 2.07 (s, 6H), 7.13–7.23 (m, 3H), 7.36–
Heating the episulfide 19 (50 mg, 0.10 mmol) in p-xylene at
reflux in the presence of copper powder (200 mg) gave the alkene 6
as a slightly coloured oil. After purification by column chromato-
graphy the oil solidified and was obtained as a white solid after
7.41 (m, 1H), 7.52–7.58 (m, 3H), 7.75–7.80 (m, 1H), 8.57 (s, 1H), 8.74–
8.77 (d, J¼8.1 Hz, 1H); 13C (75 MHz, CDCl3)
d 21.0 (q), 118.1 (d), 118.3
(d), 124.6 (d), 127.4 (d), 128.9 (s), 129.7 (d), 129.9 (d), 134.7 (d), 135.9
(s), 136.0 (d), 137.5 (s), 139.9 (s), 149.2 (s), 150.3 (s), 204.4 (s), one (s)