Cyclotrimerization of Enones and Alkynes
J. Am. Chem. Soc., Vol. 121, No. 12, 1999 2727
(6 mL) of 2d (185 mg, 1.0 mmol) was added dropwise over 2 h by
syringe pump to the reaction mixture with stirring at room temperature.
After the addition was completed, the whole mixture was stirred at the
same temperature for an additional 15 min. DBU (350 mg, 2.3 mmol)
was added to this reaction mixture in air, and this was again stirred at
room-temperature overnight. Aqueous HCl (0.2 M, 30 mL) was added,
and stirring was continued for 10 min. The aqueous layer was extracted
with ether. The combined organic layer was washed with NaHCO3 and
then with brine, dried over MgSO4 for 30 min, filtered, and concentrated
in vacuo. The residue was purified by column chromatography on silica
gel to yield a mixture of aromatic compounds 18 involving two different
regioisomers (185 mg, 51%). The structure of the major isomer 18a
(regioselectivity: 86%) was determined by an NOE experiment (see
text). An analytical sample was obtained by bulb-to-bulb distillation.
5-[(2-tert-Butyldimethylsilyl)oxyethyl]-7-(trimethylsilyl)-1-in-
danone (18a, entry 1 in Table 4): 86% isomeric purity; a colorless
oil; bp 120 °C (2 mmHg); Rf ) 0.29 (hexane:AcOEt ) 14:1); 1H NMR
(500 MHz, CDCl3) δ -0.03 (s, 6 H), 0.33 (s, 9 H), 0.85 (s, 9 H),
2.62-2.67 (m, 2 H), 2.88 (t, J ) 6.7 Hz, 2 H), 3.08-3.12 (m, 2 H),
3.05 (t, J ) 6.7 Hz, 2 H), 7.30 (br s, 1 H), 7.36 (br s, 1 H); 13C NMR
(125 MHz, CDCl3) δ -5.46, -1.05, 18.27, 25.82, 25.85, 36.10, 39.86,
64.03, 127.89, 135.15, 139.72, 139.82, 145.18, 155.92, 207.46; IR (film)
GC/MS (EI, 70 eV) m/z (rel int) 310 (M+, 25), 295 (100). Ana1. Calcd
for C19H22O2Si: C, 73.51; H, 7.14. Found: C, 73.53; H, 7.15.
5-[2-(tert-Butyldimethylsilyl)oxyethyl]-7-tert-butyl-1-indanone (en-
try 6 in Table 4): 91% regioselectivity; a pale yellow oil; bp 125 °C
1
(2 mmHg); Rf ) 0.31 (hexane:AcOEt ) 14:1); H NMR (270 MHz,
CDCl3) δ -0.03 (s, 6 H), 0.85 (s, 9 H), 1.44 (s, 9 H), 2.64-2.69 (m,
2 H), 2.86 (t, J ) 6.6 Hz, 2 H), 3.03-3.07 (m, 2 H), 3.85 (t, J ) 6.6
Hz, 2 H), 7.13 (br s, 1 H), 7.17 (br s, 1 H); 13C NMR (67.8 MHz,
CDCl3) δ -5.43, 18.28, 25.62, 25.86, 29.72, 35.66, 37.53, 39.90, 63.93,
125.19, 126.08, 132.93, 146.37, 151.80, 158.86, 206.13; IR (film) 1705
cm-1; GC/MS (EI, 70 eV) m/z (rel int) 346 (M+, 0), 289 (M+ - Bu,
100). Anal. Calcd for C21H34O2Si: C, 72.78; H, 9.89. Found: C, 72.69;
H, 10.18.
4-Methyl-5-(4-methylphenyl)-7-(trimethylsilyl)-1-indanone (26, eq
4): 93% regioselectivity; a colorless crystal (MeOH); mp 122-123 °C;
Rf ) 0.37 (hexane:AcOEt ) 9:1); 1H NMR (500 MHz, CDCl3) δ 0.33
(s, 9 H), 2.25 (s, 3 H), 2.43 (s, 3 H), 2.72 (t, J ) 5.9 Hz, 2 H), 3.07 (t,
J ) 5.9 Hz, 2 H), 7.23 (d, J ) 8.2 Hz, 2 H), 7.27 (t, J ) 8.2 Hz, 2 H),
7.42 (s, 1 H); 13C NMR (125.7 MHz, CDCl3) δ -0.92, 15.60, 21.21,
25.39, 36.23, 127.42, 128.95, 129.01, 129.65, 133.97, 136.09, 136.44,
137.11, 140.24, 155.63, 208.04; IR (disk) 1705 cm-1; GC/MS (EI, 70
eV) m/z (rel int) 294 (M+, 40), 293 (100). Ana1. Calcd for C20H24OSi:
C, 77.87; H, 7.84. Found: C, 77.79; H, 7.76.
1711 cm-1; GC/MS (EI, 70 eV) m/z (rel int) 362 (M+, 0), 347 (M+
-
Me, 23), 305 (100). Anal. Calcd for C20H34O2Si2: C, 66.24; H, 9.45.
Found: C, 66.00; H, 9.52.
6-[2-(tert-Butyldimethylsilyl)oxyethyl]-8-(trimethylsilyl)-1-tetral-
one (27, entry 7 in Table 4): >99% regioselectivity; a pale yellow
oil; bp 150 °C (2 mmHg); Rf ) 0.38 (hexane:AcOEt ) 14:1); 1H NMR
(270 MHz, CDCl3) δ -0.03 (s, 6 H), 0.28 (s, 9 H), 0.85 (s, 9 H), 2.11
(quintet, J ) 6.3 Hz, 2 H), 2.65 (t, J ) 5.9 Hz, 2 H), 2.83 (t, J ) 6.8
Hz, 2 H), 2.95 (t, J ) 5.9 Hz, 2 H), 3.83 (t, J ) 6.8 Hz, 2 H), 7.11 (br
s, 1 H), 7.41 (br s, 1 H); 13C NMR (67.8 MHz, CDCl3) δ -5.44, 0.50,
18.28, 23.15, 25.86, 30.69, 39.41, 39.63, 63.95, 130.61, 135.22, 142.95,
143.81, 144.99, 198.76; IR (film) 1682 cm-1; GC/MS (EI, 70 eV) m/z
(rel int) 376 (M+, 0), 361 (M+ - Me, 97), 319 (100), 229 (23). Anal.
Calcd for C21H36O2Si2: C, 66.96; H, 9.63. Found: C, 66.68; H, 9.72.
5-Butyl-7-(trimethylsilyl)-1-indanone (entry 2 in Table 4): 83%
regioselectivity; a colorless oil; bp 120 °C (1 mmHg); Rf ) 0.40
1
(hexane:AcOEt ) 9:1); H NMR (270 MHz, CDCl3) δ 0.33 (s, 9 H),
0.92-0.98 (m, 3 H), 1.35-1.45 (m, 2 H), 1.57-1.70 (m, 2 H), 2.61-
2.70 (m, 4 H), 3.05-3.11 (m, 2 H), 7.25 (br s, 1 H), 7.33 (br s, 1 H);
13C NMR (67.8 MHz, CDCl3) δ -1.02, 13.89, 22.45, 25.84, 33.50,
36.08, 126.94, 134.39, 139.48, 139.78, 148.75, 156.12, 207.37; IR (film)
1711 cm-1; GC/MS (EI, 70 eV) m/z (rel int) 260 (M+, 16), 245 (100).
Anal. Calcd for C16H24OSi: C, 73.79; H, 9.29. Found: C, 73.97; H,
9.24.
7-[(2-tert-Butyldimethylsilyl)oxyethyl]-9-(trimethylsilyl)-1-benzo-
suberone (28, entry 8 in Table 4): >99% regioselectivity; a colorless
oil; bp 150 °C (1 mmHg); Rf ) 0.33 (hexane:AcOEt ) 14:1); 1H NMR
(270 MHz, CDCl3) δ -0.03 (s, 6 H), 0.25 (s, 9 H), 0.85 (s, 9 H),
1.74-1.85 (m, 4 H), 2.60-2.65 (m, 2 H), 2.74-2.83 (m, 4 H), 3.82 (t,
J ) 6.8 Hz, 2 H), 6.98 (br s, 1 H), 7.33 (br s, 1 H); 13C NMR (67.8
MHz, CDCl3) δ -5.42, 0.37, 18.29, 21.54, 25.23, 25.89, 32.28, 39.45,
41.53, 64.18, 130.78, 134.42, 138.11, 139.79, 141.35, 143.83, 211.41;
IR (film) 1682 cm-1; GC/MS (EI, 70 eV) m/z (rel int) 390 (M+, 0),
375 (M+ - Me, 64), 333 (100). Anal. Calcd for C21H36O2Si2: C, 67.63;
H, 9.80. Found: C, 67.50; H, 9.80.
5-Phenyl-7-(trimethylsilyl)-1-indanone (20, entry 3 in Table 4):
>99% regioselectivity; colorless crystal (MeOH); mp 112-113 °C; Rf
1
) 0.23 (hexane:AcOEt ) 14:1); H NMR (270 MHz, CDCl3) δ 0.39
(s, 9 H), 2.71 (t, J ) 6.0 Hz, 2 H), 3.20 (t, J ) 6.0 Hz, 2 H), 7.41-
7,51 (m, 4 H), 7.62-7.65 (m, 2 H), 7.75 (br s, 1 H); 13C NMR (67.8
MHz, CDCl3) δ -1.00, 26.02, 36.23, 125.86, 127.57, 128.12, 128.91,
133.17, 140.52, 140.61, 140.68, 145.88, 156.26, 207.49; IR (disk) 1711
cm-1; GC/MS (EI, 70 eV) m/z (rel int) 280 (M+, 7), 265 (100). Ana1.
Calcd for C18H20OSi: C, 77.09; H, 7.19. Found: C, 76.85; H, 7.37.
5-(4-Methylphenyl)-7-(trimethylsilyl)-1-indanone (21, entry 4 in
Table 4): >99% regioselectivity; a colorless crystal (MeOH); mp 124-
125 °C; Rf ) 0.26 (hexane:AcOEt ) 14:1); 1H NMR (270 MHz, CDCl3)
δ 0.37 (s, 9 H), 2.42 (s, 3 H), 2.68-2.72 (m, 2 H), 3.16-3.21 (m, 2
H), 7.29 (d, J ) 8.1 Hz, 2 H), 7.53 (d, J ) 8.1 Hz, 2 H), 7.62 (br s,
1 H), 7.73 (br s, 1 H); 13C NMR (67.8 MHz, CDCl3) δ -1.00, 21.15,
26.02, 36.21, 125.55, 127.40, 129.65, 132.97, 137.74, 138.13, 140.29,
140.50, 145.80, 156.28, 207.46; IR (disk) 1705 cm-1; GC/MS (EI, 70
eV) m/z (rel int) 294 (M+, 12), 279 (100). Anal. Calcd for C19H22OSi:
C, 77.50; H, 7.53. Found: C, 77.25; H, 7.65.
5,7-Diphenyl-1-indanone (23): >99% regioselectivity; a colorless
crystal; mp 148 °C; Rf ) 0.28 (hexane:AcOEt ) 3:1);1H NMR (400
MHz, CDCl3) δ 2.71-2.75 (m, 2 H), 3.20 (t, J ) 6.2 Hz, 2 H), 7.38-
7.51 (m, 9 H), 7.64-7.67 (m, 3 H);13C NMR (100 MHz, CDCl3) δ
25.44, 37.14, 123.96, 127.47, 127.77, 127.90, 128.38, 128.86, 128.94,
129.35, 131.98, 138.02, 139.92, 141.80, 146.88, 157.13, 205.05; IR
(disk) 1711 cm-1; DI/MS (EI, 70 eV) m/z (rel int) 284 (M+, 86), 283
(100). Anal. Calcd for C21H16O: C, 88.70; H, 5.67. Found: C, 88.73;
H, 5.88.
5-(4-Methoxyphenyl)-7-(trimethylsilyl)-1-indanone (22, entry 5
in Table 4): >99% regioselectivity; a colorless crystal (MeOH); mp
1
110-111 °C; Rf ) 0.17 (hexane:AcOEt ) 9:1); H NMR (400 MHz,
Acknowledgment. This work was supported by Grants-in-
Aid for Scientific Research from the Ministry of Education,
Science and Culture, Japan, and a Sasakawa Scientific Research
Grant (from The Japan Science Society).
CDCl3) δ 0.38 (s, 9 H), 2.70 (t, J ) 6.1 Hz, 2 H), 3.18 (t, J ) 6.1 Hz,
2 H), 3.87 (s, 3 H), 7.01 (d, J ) 8.8 Hz, 2 H), 7.57 (d, J ) 8.8 Hz, 2
H), 7.60 (br s, 1 H), 7.71 (br s, 1 H); 13C NMR (67.8 MHz, CDCl3) δ
-1.00, 26.03, 36.23, 55.39, 114.40, 125.19, 128.67, 132.71, 133.04,
140.01, 140.52, 145.45, 156.34, 159.89, 207.39; IR (disk) 1705 cm-1
;
JA983348R