Photochemistry of Bicyclo[2.2.2]oct-7-ene-2,5-diones
HRMS (EI) calcd for C17H19NO2 (M+) 269.1417, found 269.1407.
Anal. Calcd for C17H19NO2: C, 75.81; H, 7.11; N, 5.20. Found:
C, 75.84; H, 7.12; N, 5.25.
obtained as a colorless oil by treating 1c (2.20 g, 8.65 mM)
with preformed Ph3PdCH2 (25.94 mM) in toluene according
to the procedure described for 3a . IR (film) 2925, 1719, 1651
cm-1; 1H NMR (400 MHz) δ 7.22-7.26 (m, 3H), 7.02-7.04 (m,
2H), 6.36 (d, J ) 6.4 Hz, 1H), 4.94 (d, J ) 1.2 Hz, 1H), 4.81 (d,
J ) 1.2 Hz, 1H), 3.02 (d, J ) 6.4 Hz, 1H), 2.38 (t, J ) 2.2 Hz,
2H), 1.15 (s, 3H), 1.06 (s, 6H); 13C NMR (100 MHz, CDCl3) δ
216.0, 144.9, 143.3, 138.3, 133.3, 128.2, 127.7, 127.0, 107.9,
54.7, 52.6, 43.6, 38.9, 26.7, 25.1, 16.5; MS (EI, 70 eV) m/z (rel
intensity) 252 (M+, 4), 182 (100), 167 (65), 152 (6); HRMS (EI)
calcd for C18H20O 252.1520, found 252.1520.
(1S*,4R*)-1,3,3-Tr im eth yl-5-h ydr oxyim in o-7,8-diph en yl-
bicyclo[2.2.2]oct-7-en -2-on e (2d ). Oxime 2d (2.48 g, 93%)
was obtained as colorless crystals by heating a mixture of 1d
(2.50 g, 7.58 mM) and hydroxylamine hydrochloride in pyridine
following the procedure described for oxime 2a . Mp 187-189
°C (hexanes-ether); IR (film) 3241, 2972, 1718 cm-1; 1H NMR
(300 MHz) δ 10.03 (br s, 1H), 7.26-6.93 (m, 10H), 3.67 (s, 1H),
2.87, 2.65 (AB q, J ) 18.9 Hz, 2H), 1.31 (s, 3H), 1.17 (s, 3H),
1.08 (s, 3H); 13C NMR (75 MHz) 214.6, 159.6, 140.8, 139.6,
138.3, 136.3, 129.4, 128.1, 127.8, 127.1, 127.0, 56.2, 52.8, 44.0,
35.3, 25.6, 25.0, 16.9; MS (EI, 70 eV) m/z (rel intensity) 345
(M+, 30), 329 (21), 288 (33), 275 (100), 258 (56), 232 (18), 215
(19); HRMS (EI) calcd for C23H23NO2 (M+) 345.1730, found
345.1722. Anal. Calcd for C23H23NO2: C, 79.97; H, 6.71; N,
4.05. Found: C, 80.13; H, 6.66; N, 4.09.
(1S*,4R*)-1,3,3-Tr im eth yl-5-m eth ylen e-7,8-d ip h en ylbi-
cyclo[2.2.2]oct-7-en -2-on e (3d ). Compound 3d (0.41 g, 96%)
was obtained as colorless crystals by treating 1d (0.43 g, 1.32
mM) with preformed Ph3PdCH2 (4.14 mM) in toluene following
the procedure described for 3a . Mp 101-102 °C (from ether);
IR (film) 2970, 1717 cm-1 1H NMR (400 MHz) δ 6.90-7.20
;
(m, 10H), 5.12 (d, J ) 1.2 Hz, 1H), 4.94 (d, J ) 1.2 Hz, 1H),
3.40 (s, 1H), 2.52 and 2.56 (ABq, J ) 17.0 Hz, 2H), 1.26 (s,
3H), 1.14 (s, 3H), 1.00 (s, 3H); 13C NMR (100 MHz) δ 216.0,
144.9, 143.1, 139.4, 137.2, 136.9, 129.6, 128.0, 127.9, 127.8,
127.7, 126.7, 126.5, 108.2, 61.1, 52.8, 43.8, 39.1, 25.8, 24.9, 17.0;
MS (EI, 70 eV) m/z (rel intensity) 328 (M+, 25), 258 (100), 243
(65), 181 (7), 165 (10); HRMS (EI) calcd for C24H24O 328.1827,
found 328.1823. Anal. Calcd for C24H24O: C, 87.80; H, 7.32.
Found: C, 87.79; H, 7.30.
Rep r esen ta tive P r oced u r e for th e P r ep a r a tion of
Com p ou n d s 3a -d . (1S*,4S*)-1,3,3-Tr im eth yl-5-m eth yl-
en e-7-eth oxyca r bon ylbicyclo[2.2.2]oct-7-en -2-on e (3a ). To
a solution of 1a (1.16 g, 4.64 mM) in toluene (50 mL) was added
with stirring a solution of Ph3PdCH2 (14. 6 mM), prepared
prior to the Wittig reaction by adding potassium tert-amyl
oxide in toluene (80 mL) to a solution of Ph3MePBr in toluene
(40 mL) and then heating at 70 °C for 1 h in toluene (120 mL).
The resulting mixture was heated at 70 °C for 2 h with
vigorous stirring under nitrogen. Then the reaction mixture
was allowed to cool to room temperature, 1.0 M HCl was
added, and the reaction mixture was extracted with ether. The
combined organic layers were washed with saturated NaHCO3
followed by brine. The organic layer was dried over anhydrous
MgSO4 and concentrated. The residue was purified by column
chromatography (EtOAc/hexanes 1:9) on silica gel to obtain
3a (0.48 g, 42%) as a colorless solid. Mp 61-62 °C (from ethyl
Ir r a d ia tion of 1a -d in Acetop h en on e/Aceton e/Meth a -
n ol: Ir r a d ia tion of 1a . A solution of 1a (0.1 g, 0.4 mM) in
freshly distilled acetophenone (2 mL) in a Pyrex vessel was
irradiated for 8.5 h at 350 nm. Removal of acetophenone under
reduced pressure (50 °C at 0.05 Torr) followed by column
chromatography of the residue on silica gel with 20% ethyl
acetate in hexanes afforded 9a (98 mg, 98%) as a colorless oil.
A solution of 1a (0.05 g, 0.20 mM) in acetone (5 mL) in a
Pyrex vessel was irradiated for 8 h at 300 nm. Removal of
acetone on a rotavapor followed by column chromatography
of the residue on silica gel with 2.5% methanol in chloroform
as eluent furnished 9a (28 mg, 56%) and phenol 11a (9 mg,
24%).
A solution of 1a (0.05 g, 0.20 mM) in methanol (5 mL) in a
Pyrex vessel was irradiated for 15 h at 300 nm. Removal of
methanol on a rotavapor followed by column chromatography
of the residue on silica gel with 2.5% methanol in chloroform
as eluent furnished 9a (10 mg, 20%) and phenol 11a (16 mg,
50%).
acetate-hexanes); IR (film) 2975, 1722 cm-1 1H NMR (400
;
MHz, C6D6) δ 7.21 (d, J ) 6.6 Hz, 1H), 4.75 (d, J ) 1.2 Hz,
1H), 4.60 (d, J ) 1.2 Hz, 1H), 3.92-3.95 (m, 2H), 2.61 (d, J )
6.6 Hz, 1H), 1.99 (dd, J ) 17.2, 3.7 Hz, 1H), 1.98 (dd, J ) 17.2,
3.7 Hz, 1H), 1.68 (s, 3H), 0.95 (s, 3H), 0.93 (t, J ) 6.2 Hz, 3H),
0.93 (s, 3H); 13C NMR (100 MHz, C6D6) δ 213.6, 164.9, 146.0,
144.4, 134.7, 110.2, 61.1, 55.7, 52.1, 43.5, 39.6, 27.1, 25.9, 17.4,
14.8; MS (EI, 70 eV) m/z (rel intensity) 248 (M+, 1), 203 (19),
178 (91), 133 (13), 105 (100); HRMS (EI) calcd for C15H20O3
248.1412, found 248.1403. Anal. Calcd for C15H20O3: C, 72.54;
H, 8.12. Found: C, 72.43; H, 8.13.
Eth yl (1S*,2S*,5S*,8S*)-5,7,7-Tr im eth yl-3,6-d ioxotr i-
cyclo[3.3.0.02,8]octa n e-1-ca r boxyla te (9a ). IR (film) 2930,
(1S*,4R*)-1,3,3-Tr im et h yl-5-m et h ylen e-7,8-b is(m et h -
oxyca r bon yl)bicyclo[2.2.2]oct-7-en -2-on e (3b). Compound
3b (0.40 g, 25%) was obtained as a slightly yellowish oil along
with compound 8 (0.50 g, 37%), when 1b (1.37 g, 4.66 mM)
was treated with preformed Ph3PdCH2 (7.37 mM) in toluene
following the procedure described for 3a . 3b: IR (film) 2961,
1
1733, 1457 cm-1; H NMR (400 MHz) δ 4.15 (q, J ) 7.6 Hz,
2H), 2.72 (d, J ) 9.6 Hz, 1H), 2.64 (d, J ) 18.4 Hz, 1H), 2.54
(d, J ) 9.6 Hz, 1H), 2.14 (d, J ) 18.4 Hz, 1H), 1.55 (s, 3H),
1.23 (t, J ) 7.6 Hz, 3H), 1.21 (s, 3H), 1.08 (s, 3H); 13C NMR
(100 MHz) δ 220.8, 207.7, 169.3, 61.2, 55.4, 53.1, 46.4, 46.3,
43.8, 43.4, 26.4, 22.9, 17.7, 14.0; MS (EI, 70 eV) m/z (rel
intensity) 250 (M+, 6), 222 (28), 194 (100), 179 (38), 165 (33),
121 (78); HRMS (EI) calcd for C14H18O4 250.1205, found
250.1216.
1
1728 cm-1; H NMR (400 MHz, C6D6) δ 4.90 (dd, J ) 2.9, 2.0
Hz, 1H), 4.61 (dd, J ) 2.9, 2.0 Hz, 1H), 3.61 (s, 1H), 3.46 (s,
3H), 3.29 (s, 3H), 2.11 (dd, J ) 17.2, 2.0 Hz, 1H), 1.93 (dd, J
) 17.2, 2.0 Hz, 1H), 1.31 (s, 3H), 1.07 (s, 3H), 0.96 (s, 3H); 13
C
NMR (100 MHz, C6D6) δ 212.5, 166.7, 164.2, 145.3, 143.4,
135.7, 111.1, 55.1, 53.0, 52.6, 52.4, 43.3, 38.8, 26.2, 25.4, 15.3;
MS (EI, 70 eV) m/z (rel intensity) 292 (M+, 4), 222 (23), 204
(25), 191 (70), 178 (24), 163 (100), 145 (64); HRMS (EI) calcd
for C16H20O5 292.1311, found 292.1310. Compound 8: IR (film)
2964, 1726 cm-1; 1H NMR (400 MHz) δ 4.99 (s, 2H), 4.96 (dd,
J ) 2.0, 1.6 Hz, 1H), 4.84 (dd, J ) 2.0, 1.6 Hz, 1H), 3.68 (s,
3H), 3.12 (s, 1H), 2.42 (dd, J ) 16.9, 2.0 Hz, 1H), 2.33 (dd, J
) 16.9, 2.0 Hz, 1H), 1.89 (s, 3H), 1.22 (s, 3H), 1.09 (s, 3H),
1.06 (s, 3H); 13C NMR (100 MHz) δ 213.9, 167.0, 148.2, 143.3,
141.7, 128.6, 114.9, 109.2, 57.8, 51.3, 50.1, 42.9, 38.3, 25.1, 24.7,
20.7, 14.9; MS (EI, 70 eV) m/z (rel intensity) 290 (M+, 1), 274
(26), 204 (32), 145 (91), 84 (100); HRMS (EI) calcd for C17H22O4
290.1518, found 290.1518.
Eth yl 4-Hyd r oxy-2-m eth ylben zoa te (11a ). Mp 88-89 °C
(from EtOAc-hexanes); IR (film) 3293, 2950, 1690, 1600 cm-1
;
1H NMR (400 MHz) δ 7.89 (dd, J ) 5.0, 2.8 Hz, 1H), 6.70 (d,
J ) 5.0 Hz, 1H), 6.69 (d, J ) 2.8 Hz, 1H), 4.33 (q, J ) 7.2 Hz,
2H), 2.57 (s, 3H), 1.38 (t, J ) 7.2 Hz, 3H); 13C NMR (100 MHz)
δ 167. 6, 158.9, 143.3, 133.2, 121.9, 118.3, 112.6, 60.6, 22.1,
14.3; MS (70 eV) m/z (rel intensity) 180 (M+, 31), 152 (10), 135
(100), 107 (20), 77 (32), 29 (17); HRMS (EI) calcd for C10H12O3
180.0786, found 180.0791. Anal. Calcd for C10H12O3: C, 66.65;
H, 6.71. Found: C, 66.66, H, 6.71.
Ir r a d ia tion of 1b. A solution of 1b (0.49 g, 1.66 mM) in
freshly distilled acetophenone (5 mL) in a Pyrex vessel was
irradiated for 6 d at 350 nm. Removal of acetophenone under
reduced pressure (50 °C at 0.05 Torr) followed by recrystal-
ization of the residue in dichloromethane-hexanes afforded
10b (0.44 g, 90%) as colorless crystals.
(1S*,4S*)-1,3,3-Tr im eth yl-5-m eth ylen e-7-ph en ylbicyclo-
[2.2.2]oct-7-en -2-on e (3c). Compound 3c (1.96 g, 90%) was
J . Org. Chem, Vol. 68, No. 17, 2003 6549