5
64
Frey, Duan, Ghiviriga, Hudlický:
0
1
2
.88 (s, 9 H); 0.10 (s, 3 H); 0.05 (s, 3 H). 13C NMR (125 MHz, CDCl ): 156.9, 146.9, 145.6,
33.3, 132.6, 121.3, 118.2, 117.9, 112.1, 98.5, 65.0, 56.1, 56.0, 53.8, 48.2, 37.8, 36.2, 29.4,
3
5.8, 18.1, –4.7, –5.1. HR MS: calculated for C24H35NO Si 445.2284, foun d 445.2223.
5
3
-(2-{6S-(2-Brom o-6-m eth oxyph en oxy)-5S-[tert-butyl(dim eth yl)silyloxy)-
cycloh ex-1-en -1-yl}eth yl)oxazol-2(3H)-on e (14)
To a stirred solution of 3-(2-{5S-[tert-butyl(dim eth yl)silyloxy)-6R-h ydroxycycloh ex-1-en -1-yl}-
8
eth yl)oxazol-2(3H)-on e (0.26 g, 0.78 m m ol) an d 6-brom o-2-m eth oxyph en ol (0.16 g, 0.82
m m ol) in dry THF (1.0 m l) at 0 °C was added a solution of th e Mitsun obu reagen t, wh ich
h ad been previously prepared by th e addition of DEAD (0.28 m l, 1.6 m m ol) to a stirred solu-
tion of Bu P (0.39 m l, 1.6 m m ol) in dry THF (1.0 m l) at 0 °C, an d stirred at th e sam e tem -
3
perature for 15 m in . Th e reaction m ixture was allowed to warm to room tem perature. After
1
8 h , th e solven ts were evaporated un der reduced pressure. Th e crude product was purified
by flash ch rom atograph y (h exan es–EtOAc 9 : 1) to yield pure 14 (0.30 g, 73%) as a colorless
3
0
oil; RF 0.53 (h exan es–EtOAc 1 : 1); [α]D +54.0 (c 1.0, CH Cl ). IR (KBr): 2 955, 2 924, 2 851,
2
2
1
1
(
747, 1 693, 1 650, 1 582, 1 555, 1 469, 1 404, 1 257, 1 222, 1 081, 1 031, 967, 835, 768. H NMR
CDCl , 500 MHz): 7.15 (dd, J = 8.1, 1.6, 1 H); 6.93 (t, J = 8.1, 1 H); 6.87 (dd, J = 8.2, 1.5,
3
1
4
2
H); 6.67 (d, J = 2.2, 1 H); 6.64 (d, J = 2.0, 1 H); 5.76 (d, J = 5.2, 1 H); 4.50 (m ); 3.99 (dt, J =
.0, 2.0, 1 H); 3.90 (dt, J = 13.8, 6.9, 1 H); 3.86 (s, 3 H); 3.69 (ddd, J = 13.7, 7.5, 6.1, 1 H);
.75 (dt, J = 13.8, 6.9, 1 H); 2.47 (dt, J = 14.0, 7.0, 1 H); 2.23 (m ); 2.18 (m ); 1.98 (m ); 1.67
1
3
(
m ); 0.73 (s, 9 H); –0.16 (s, 3 H); –0.19 (s, 3 H). C NMR (75 MHz): 155.8, 153.3, 144.0,
1
2
32.6, 129.2, 126.3, 125.2, 124.8, 118.2, 117.3, 111.5, 79.2, 67.1, 55.7, 42.8, 34.8, 25.6, 24.8,
0.6, 18.1, –5.2. HR MS: calculated for C24H35BrNO Si 524.1468, foun d 524.1420.
5
3
-(2-(5aS,6S,9aR)-6-[tert-Butyl(dim eth yl)silyloxy)]-4-m eth oxy-5a,6,7,9a-tetrah ydro-
ben zo[b][1]ben zofuran -9a-yl}eth yl)oxazol-2(3H)-on e (16)
A flam e-dried h eavy-walled Pyrex tube un der static argon atm osph ere was ch arged with 14
(
(
40 m g, 0.08 m m ol), Pd(PPh 3)4 (9 m g, 0.008 m m ol), PPh 3 (8 m g, 0.03 m m ol), trieth ylam in e
0.02 m l, 0.15 m m ol), an d toluen e (5.0 m l). Th e tube was capped with a self-sealin g, rub-
ber-lin ed cap an d h eated to 120 °C. After 19 days, th e solven ts were evaporated un der re-
duced pressure. Th e crude product was purified by preparative th in -layer ch rom atograph y
(
h exan es–EtOAc 9 : 1, eluted 10 tim es) to yield 16 (4.4 m g, 13%) as a colorless oil, alon g
2
5
with 53% recovered startin g m aterial 14; RF 0.52 (h exan es–EtOAc 1 : 1); [α] +59.0 (c 1.0,
CH Cl ) (Note: th is sam ple was sh own to be 74% pure by HPLC in MeOH–H O). H NMR
D
1
2
2
2
(
CDCl , 500 MHz): 6.86 (dd, J = 8.1, 7.6, 1 H); 6.76 (dd, J = 8.2, 1.1, 1 H); 6.73 (d, J = 2.0,
3
1
H); 6.72 (dd, J = 7.7, 1.1, 1 H); 6.38 (d, J = 2.1, 1 H); 5.76 (dt, J = 10.0, 1.3, 1 H); 5.71 (ddd,
J = 9.9, 4.3, 3.4, 1 H); 4.56 (d, J = 6.6, 1 H); 4.04 (ddd, J = 7.1, 6.7, 4.8, 1 H); 3.86 (s, 3 H);
3
1
.65 (ddd, J = 14.0, 10.1, 6.3, 1 H); 3.50 (ddd, J = 14.2, 10.6, 5.8, 1 H); 2.30 (dt, J = 16.9, 4.7,
H); 2.11 (m , 1 H); 2.07 (m , 1 H); 0.91 (s, 9 H); 0.14 (s, 3 H); 0.06 (s, 3 H). 1 C NMR
3
(
CDCl , 125 MHz): 155.6, 146.0, 145.3, 134.4, 129.3, 127.7, 124.4, 122.1, 115.6, 115.1, 89.8,
3
6
4
7.8, 56.0, 49.4, 40.7, 38.7, 30.1, 25.9, 18.3, –4.6, –5.4. HR MS: calculated for C24H34NO Si
44.2206, foun d 444.2173.
5
Collect. Czech. Chem. Commun. (Vol. 65) (2000)