Junker et al.
JOCArticle
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475.0721. Diastereomeric ratio 17.0:1 (determined by H NMR
integrations).
H-7a), 2.57 (dd, J = 15.8, 4.7 Hz, 1H, H-70), 2.48 (ddd, J = 15.8,
7.6, 1.8 Hz, 1H, H-7), 0.40 (s, 6H, H-8). 13C NMR (75.5 MHz,
CDCl3) δ 178.6 (C, C-1), 178.2 (C, C-3), 141.3 (C, C-13), 140.7
(CH, C-5), 140.2 (C, C-6), 133.9 (CH), 131.9 (C, C-17), 129.3
(CH), 129.1 (CH), 128.8 (CH), 128.5 (CH), 128.0 (CH), 127.6
(CH), 126.8 (CH), 126.3 (CH), 46.6 (CH, C-3a), 41.3 (CH, C-4),
39.1 (CH, C-7a), 26.4 (CH2, C-7), -3.88 (CH3, C-8). HRMS
[M þ Na]þ calcd for C28H27NO2SiNa 460.1709, found 460.1727.
Diastereomeric ratio 9.0:1 (determined by 1H NMR integrations).
endo-6-(Benzyldimethylsilyl)-2,4-diphenyl-3a,4,7,7a-tetrahydro-
1H-isoindole-1,3(2H)-dione (23a). Diene (22a) (0.252 g, 0.905
mmol), N-phenylmaleimide (0.134 g, 0.774 mmol), and THF (5 mL)
were used according to the general procedure. After 24 h at 50 °C
the reaction solution was condensed by rotary evaporation and
dried under vacuum overnight. The resulting yellow residue was
purified by flash chromatography with silica gel and 2:1 hexanes/
ethyl acetate as eluent to yield a white powder (0.245 g, 0.542
mmol, 70%): Rf 0.4 (hexanes/ethyl acetate, 2:1); mp 135-138 °C.
1H NMR (300 MHz, CDCl3) δ 7.38-7.18 (m, 10H), 7.12-6.98
(m, 3H), 6.89-6.84 (m, 2H, H-19), 6.55 (dd, J = 4.5, 1.9 Hz, 1H,
H-5), 3.83(m, 1H, H-4), 3.45 (dd, J = 9.0, 6.9 Hz, 1H, H-3a), 3.34
(dt, J = 8.8, 2.6 Hz, 1H, H-7a), 2.98 (dd, J = 16.4, 2.6 Hz, 1H,
H-7/70), 2.42 (ddt, J = 16.4, 8.3, 1.9 Hz, 1H, H-7/70), 2.26 (d, J =
13.7 Hz, 1H, H-9), 2.19 (d, J = 13.7 Hz, 1H, H-9), 0.14 (s, 6H,
H-8). 13C NMR (125.7 MHz, CDCl3) δ 178.3 (C, C-1), 176.2 (C,
C-3), 140.0 (C), 139.6 (CH, C-5), 139.4 (C), 138.6 (C), 131.7 (C),
129.1 (CH), 128.9 (CH), 128.4 (CH), 128.3 (CH), 128.2 (CH),
128.1 (CH), 127.2 (CH), 126.2 (CH), 124.2 (CH), 45.2 (CH,
C-3a), 42.2 (CH, C-4), 39.1 (CH, C-7a), 25.6 (CH2, C-7), 24.9
(CH2, C-9), -4.2 (CH3, C-8), -4.3(CH3, C-8). HRMS[M þ Cs]þ
calcd for C29H29NO2Si 584.1022, found 584.1051. Diastereomeric
ratio 14.0:1 (determined by 1H NMR integrations).
endo-6-(Benzyldimethylsilyl)-4-(4-methoxyphenyl)-2-phenyl-3a,
4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione (23b). Diene (22b)
(0.174 g, 0.564 mmol), N-phenylmaleimide (0.086 g, 0.497 mmol),
and THF (2 mL) were used according to the general procedure.
After 16 h at 50 °C the reaction solution was condensed by rotary
evaporation and dried under vacuum overnight. The resulting
yellow residue was purified by flash chromatography with silica
gel and 4:1 chloroform/ethyl acetate as eluent to yield a white solid
(0.079 g, 0.164 mmol, 33%): Rf 0.6 (chloroform/ethyl acetate, 2:1);
mp 89-93 °C. 1H NMR (300 MHz, CDCl3) δ 7.38-7.29 (m, 3H),
7.24-6.97 (m, 7H), 6.91-6.82 (m, 4H), 6.51 (dd, J = 4.7, 1.8 Hz,
1H, H-5), 3.81 (m, 1H, H-4), 3.79 (s, 3H, H-18), 3.40 (dd, J = 9.0,
6.7 Hz, 1H, H-3a), 3.32 (dt, J = 8.5, 2.5 Hz, 1H, H-7a), 2.96 (dd,
J = 16.6, 2.5 Hz, 1H, H-7/70), 2.41 (ddt, J = 16.6, 8.5, 1.8 Hz, 1H,
H-7/70), 2.24 (d, J = 13.7 Hz, 1H, H-9), 2.18 (d, J = 13.7 Hz, 1H,
H-9), 0.13 (as, 3H, H-8), 0.12 (as, 3H, H-8). 13C NMR (75.5 MHz,
CDCl3) δ 178.4 (C, C-1), 176.4 (C, C-3), 158.8 (C), 139.9 (CH),
139.7 (C), 139.5 (C), 131.7 (C), 130.5 (C), 130.1 (CH), 128.9 (CH),
128.4 (CH), 128.3 (CH), 128.2 (CH), 126.2 (CH), 124.2 (CH),
113.8 (CH), 55.3 (CH3, C-18), 45.3 (CH, C-3a), 41.5 (CH, C-4),
39.0 (CH, C-7a), 25.5 (CH2, C-7), 24.9 (CH2, C-9), -4.1 (CH3,
C-8), -4.2 (CH3, C-8). HRMS [M þ Na]þ calcd for C30H31NO3-
SiNa 504.1971, found 504.2002. Diastereomeric ratio 26.3:1 (deter-
mined by 1H NMR integrations).
2,4-Diphenyl-6-(triethylsilyl)-3a,4,7,7a-tetrahydro-1H-isoin-
dole-1,3(2H)-dione (17d and 18d). Diene (11a) (0.254 g, 1.04
mmol), N-phenylmaleimide (0.214 g, 1.24 mmol), and THF (5 mL)
were used according to the general procedure. After 24 h at 90 °C
the reaction solution was condensed by rotary evaporation and
dried under vacuum overnight. The resulting yellow residue was
purified by flash chromatography with silica gel and 2:1 hexanes/
ethyl acetate as eluent to yield the two diastereomers. Major
diastereomer (17d) (endo): white powder (0.236 g, 0.565 mmol,
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54%); Rf 0.4 (hexanes/ethyl acetate, 2:1); mp 116-117 °C. H
NMR (500 MHz, CDCl3) δ 7.37-7.22 (m, 8H), 6.93-6.89 (m,
2H, H-15), 6.55 (dd, J = 4.4, 2.2 Hz, 1H, H-5), 3.84 (m, 1H, H-4),
3.46 (dd, J = 9.1, 6.9 Hz, 1H, H-3a), 3.36 (td, J = 8.8, 2.7 Hz, 1H,
H-7a), 3.02 (dd, J = 16.4, 2.6 Hz, 1H, H-70), 2.47 (ddt, J = 16.3,
8.6, 1.9 Hz, 1H, H-7), 0.944 (t, J = 8.0 Hz, 9H, H-9), 0.662 (q, J =
8.0 Hz, 6H, H-8). 13C NMR (125.7 MHz, CDCl3) δ 178.38 (C,
C-1), 176.20 (C, C-3), 139.81 (CH, C-5), 139.02 (C, C-10), 138.94
(C, C-6), 131.74 (C, C-14), 129.12 (CH), 128.85 (CH), 128.34
(CH), 128.28 (CH), 127.14 (CH), 126.22 (CH, C-15), 45.28 (CH,
C-3a), 42.15 (CH, C-4), 39.10 (CH, C-7a), 25.99 (CH2, C-7), 7.39
(CH3, C-9), 2.36 (CH2, C-8). GC/MS: m/z (relative, %) 417.3 (2)
[Mþ], 390.2 (9), 389.2 (32), 388.2 (100), 230.1 (4), 215.1 (25),
187.1 (8), 185.1 (6), 159.1 (10), 157.0 (6), 145.0 (5), 131.0 (14), 129.
1 (9), 115.1 (8), 87.1 (15), 59.1 (15). HRMS [M þ Cs]þ calcd for
C26H31NO2Si 550.1179, found 550.1192. Minor diastereomer
(18d) (exo): white powder (0.074 g, 0.177 mmol, 17%); Rf 0.5
(hexanes/ethyl acetate, 2:1); mp 78-79 °C. 1H NMR (500 MHz,
CDCl3) δ 7.47-7.25 (m, 10H), 6.41 (dd, J = 5.6, 1.9 Hz, 1H,
H-5), 4.12 (dd, J = 5.2, 3.7 Hz, 1H, H-4), 3.44 (dd, J = 9.3, 3.5
Hz, 1H, H-3a), 3.18 (ddd, J = 9.3, 7.6, 4.5 Hz, 1H, H-7a), 2.56
(dd, J = 15.6, 4.5 Hz, 1H, H-70), 2.49 (ddd, J = 15.6, 7.6, 1.9 Hz,
1H, H-7), 0.929 (t, J =7.9 Hz, 9H, H-9), 0.642(q, J =7.9 Hz, 6H,
H-8). 13C NMR (125.7 MHz, CDCl3) δ 178.87 (C, C-1), 178.33
(C, C-3), 141.46 (C, C-10), 140.33 (CH, C-5), 139.12 (C, C-6),
131.95 (C, C-14), 129.07 (CH), 128.79 (CH), 128.50 (CH), 127.60
(CH), 126.75 (CH), 126.27 (CH), 46.68 (CH, C-3a), 41.20 (CH,
C-4), 39.00 (CH, C-7a), 26.51 (CH2, C-7), 7.41 (CH3, C-9), 2.25
(CH2, C-8). HRMS [M þ Cs]þ calcd for C26H31NO2Si 550.1179,
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found 550.1197. Diastereomeric ratio 3.4:1 (determined by H
NMR integrations).
6-(Dimethyl(phenyl)silyl)-2,4-diphenyl-3a,4,7,7a-tetrahydro-1H-
isoindole-1,3(2H)-dione (17f and 18f). Diene (11b) (0.075 g, 0.284
mmol), N-phenylmaleimide (0.038 g, 0.219 mmol), and THF
(3 mL) were used according to the general procedure. After 16 h
at 90 °C the reaction solution was condensed by rotary evapora-
tion and dried under vacuum overnight. The resulting colorless
residue was purified by flash chromatography with silica gel and
2:1 hexanes/ethyl acetate as eluent to yield the two diastereomers.
Major diastereomer (17f) (endo): colorless residue (0.080 g, 0.183
mmol, 83%); Rf 0.5 (hexanes/ethyl acetate, 2:1). 1H NMR (300
MHz, CDCl3) δ 7.53-7.23 (m, 13H), 6.83-6.79 (m, 2H, H-18),
6.62 (dd, J = 4.6, 2.1 Hz, 1H, H-5), 3.84 (m, 1H, H-4), 3.46 (dd,
J = 9.0, 6.8 Hz, 1H, H-3a), 3.35 (dt, J = 8.7, 2.5 Hz, 1H, H-7a),
3.03 (dd, J = 16.4, 2.4 Hz, 1H, H-70), 2.47 (ddt, J = 16.3, 8.6, 1.9
Hz, 1H, H-7), 0.43 (as, 3H, H-8), 0.42 (as, 3H, H-8). 13C NMR
(75.5 MHz, CDCl3) δ 178.2 (C, C-1), 176.2 (C, C-3), 140.2 (CH,
C-5), 140.0 (C, C-13), 138.8 (C, C-6), 136.8 (C, C-9), 133.9 (CH),
131.7 (C, C-17), 129.3 (CH), 129.1 (CH), 128.9 (CH), 128.4 (CH),
128.3 (CH), 127.9 (CH), 127.2 (CH), 126.3 (CH, C-18), 45.3 (CH,
C-3a), 42.3 (CH, C-4), 39.1 (CH, C-7a), 25.9 (CH2, C-7), -3.74
(CH3, C-8). HRMS [M þ Na]þ calcd for C28H27NO2SiNa
460.1709, found 460.1703. Minor diastereomer (18f) (exo): color-
less residue (0.009 g, 0.021 mmol, 9%); Rf 0.6 (hexanes/ethyl
acetate, 2:1). 1H NMR (300 MHz, CDCl3) δ 7.50-7.16 (m, 15H),
6.47 (dd, J = 5.7, 1.5 Hz, 1H, H-5), 4.11 (m, 1H, H-4), 3.44 (dd,
J = 9.3, 3.6 Hz, 1H, H-3a), 3.17 (ddd, J = 9.3, 7.5, 4.6 Hz, 1H,
endo-6-(Benzyldimethylsilyl)-4-(4-chlorophenyl)-2-phenyl-3a,4,
7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione (23c). Diene (22c)
(0.920 g, 2.94 mmol), N-phenylmaleimide (0.514 g, 2.97 mmol),
and THF (12 mL) were used according to the general procedure.
After 19 h at 50 °C the reaction solution was condensed by rotary
evaporation and dried under vacuum overnight. The resulting
yellow residue was purified by flash chromatography with silica
gel and 2:1 hexanes/ethyl acetate as eluent to yield a white crystal-
line solid (0.925 g, 1.90 mmol, 65%): Rf 0.3 (hexanes/ethyl acetate,
2:1); mp 102-105 °C. 1HNMR (500MHz, CDCl3) δ7.37 (m, 2H),
7.30 (m, 3H), 7.18 (m, 4H), 7.08 (m, 1H), 6.99 (m, 1H), 6.93 (m,
2H), 6.48 (dd, J = 4.5, 2.2 Hz, 1H, H-5), 3.75 (at, J = 5.5 Hz, 1H,
8162 J. Org. Chem. Vol. 75, No. 23, 2010