Notes
J . Org. Chem., Vol. 61, No. 26, 1996 9633
+44 (c ) 1.4, CHCl3). Anal. Calcd for C16H28NO3Si: C, 49.23;
H, 7.23; N, 3.59. Found: C, 49.37; H, 7.15; N, 3.51.
value for the synthesis of various homochiral com-
pounds.13
Gen er a l P r oced u r e for th e Ad d ition of Or ga n ocop p er
Rea gen ts on Sila br om oa llen e 7a . Rea ction of th e Low er
Or d er Or ga n ocu p r a tes Der ived fr om Meth yl-, Bu tyl-, a n d
P h en yllith iu m . A suspension of copper(I) cyanide (8 equiv) in
ether at 0 °C was treated dropwise with the corresponding
lithium derivative (8 equiv). The mixture was stirred for 30 min
at 0 °C. After the mixture was cooled to -78 °C, a solution of
silabromoallene 7a (1 equiv) in dry THF was added. After being
stirred for 2 h at -78 °C, the mixture was quenched with a
saturated NH4Cl solution and extracted with ether. The organic
layer was dried (Na2SO4) and concentrated in vacuo. The crude
product was purified by chromatography (hexane/ether 90/10)
to give the final product as a single diastereomer.
(ii) Rea ction of th e High er Or d er Or ga n ocu p r a tes
Der ived fr om Meth yl-, Bu tyl-, a n d P h en yllith iu m . The
procedure is the same as the one above, except that 2 equiv of
the lithium derivative was added for each equivalent of
copper(I) cyanide. Moreover, the reaction mixture was allowed
to warm to room temperature before being quenched.
(iii) Rea ction w ith Meth yl a n d P h en yl Or ga n ocu p r a tes
Der ived fr om Gr ign a r d Rea gen ts. To a solution of dry LiBr
(8 equiv) and CuBr‚Me2S (8 equiv) in THF was added at -30
°C the corresponding Grignard reagent (8 equiv). The mixture
was stirred for 30 min at -30 °C. After the mixture was cooled
to -78 °C, a solution of silabromoallene 7a (1 equiv) in dry THF
was added. The reaction mixture was stirred for 10 min at -78
°C before being allowed to warm to room temperature. After
being stirred for 1 h at room temperature, the mixture was
quenched with saturated NH4Cl, extracted with ether, and dried.
Chromatography (hexane/ether 90/10) gave the final product as
a single diastereomer.
Exp er im en ta l Section
1H and 13C NMR spectra were obtained in CDCl3 and at room
temperature (unless otherwise noted); coupling constant J values
are in hertz. Mass spectra were recorded on a low-resolution
instrument by CI at 70 eV, unless otherwise noted. IR spectra
were recorded in CCl4 and measured in cm-1
. Air- and/or
moisture-sensitive reactions were conducted under an atmo-
sphere of dry argon using oven-dried glassware and standard
syringe/septum techniques. THF and ether were distilled from
sodium benzophenone and methylene chloride from CaH2 prior
to use. The organic extracts of crude products were dried over
anhydrous Na2SO4. The organic solvents were removed by
evaporation under reduced pressure with a rotary evaporator.
The column chromatographies were performed by using a flash
chromatography technique.
Gen er a l P r oced u r e for th e Syn th esis of Tosyla tes 6. To
a solution of the corresponding alcohol 5a or 5b (4.47 g, 13.6
mmol), triethylamine (2.86 mL, 20.4 mmol), and (dimethyl-
amino)pyridine (2.49 g, 20.4 mmol), in dichloromethane (91 mL)
at 0 °C was added p-toluenesulfonyl chloride (3.24 g, 17 mmol).
The reaction mixture was stirred at room temperature overnight,
quenched with a saturated aqueous solution of NH4Cl (30 mL),
and extracted with CH2Cl2 (3 × 50 mL). After drying and
evaporation of the solvent, purification by chromatography
(hexane/ether 90/10) gave the final product.
ter t-Bu tyl (1′S,4R)-4-[1′-(Tosyloxy)-3′-(tr im eth ylsilyl)-2′-
p r op yn yl]oxa zolid in e-3-ca r boxyla te (6a ). Yield: 88%, oil.
1H NMR (50 °C): δ 0.01 (s, 9H), 1.47 (s, 3H), 1.51 (s, 9H), 1.60
(s, 3H), 2.41 (s, 3H), 3.96-4.19 (m, 3H), 5.60 (br s, 1H), 7.28 (d,
J ) 8, 2H), 7.8 (d, J ) 8, 2H). 13C NMR (50 °C): δ -0.6, 21.4,
24.8, 26.2, 28.4, 60.7, 63.3, 69.6, 80.8, 81.3, 96.0, 98.1, 128.2,
129.5, 134.5, 144.4, 154.7. [R]23D ) +92 (c ) 1.4, CHCl3). Anal.
Calcd for C23H35NO6SSi: C, 57.35; H, 7.32; N, 2.90. Found: C,
57.26; H, 7.12; N, 2.77.
ter t-Bu tyl (1′R,4R)-4-[1′-(Tosyloxy)-3′-(tr im eth ylsilyl)-2′-
p r op yn yl]oxa zolid in e-3-ca r boxyla te (6b). Yield: 89%, oil.
1H NMR (50 °C): δ 0.04 (s, 9H), 1.47 (s, 3H), 1.49 (s, 9H), 1.56
(s, 3H), 2.42 (s, 3H), 3.98-4.13 (m, 3H), 5.60 (br s,1H), 7.30 (d,
J ) 8.4, 2H), 7.80 (d, J ) 8.3, 2H). 13C NMR (50 °C): δ -0.5,
21.4, 23.2, 27.5, 28.3, 59.5, 64.4, 65.9, 81.1, 95.1, 97.0, 110.4,
126.2, 128.2, 129.9, 140.6, 156.2. [R]23D ) +56 (c ) 1.4, CHCl3).
Anal. Calcd for C23H35NO6SSi: C, 57.35; H, 7.32; N, 2.90.
Found: C, 57.23; H, 7.27; N, 2.88.
ter t-Bu t yl (3′S,4R)-4-[3′-P h en yl-3′-(t r im et h ylsilyl)-1′,2′-
p r op a n ed ien yl]oxa zolid in e-3-ca r boxyla te (8a ). 1H NMR
(50 °C): δ 0.27 (s, 9H), 1.47 (s, 9H), 1.52 (s, 3H), 1.59 (s, 3H),
3.94-4.08 (m, 2H), 4.48-4.55 (m, 1H), 5.44 (d, J ) 5.2, 1H), 7.16-
7.36 (m, 5H). 13C NMR (50 °C): δ -0.4, 24.5, 26.9, 28.4, 55.5,
67.8, 79.9, 81.2, 88.5, 94.4, 126.2, 127.8, 128.3, 137.2, 151.7,
202.5. IR: 3063, 2983, 2876, 1927, 1695, 1597, 1491, 1387, 1093,
844. [R]23 ) +118 (c ) 3, EtOH). Anal. Calcd for C22H33NO3-
D
Si: C, 68.17; H, 8.81; N, 3.61. Found: C, 68.10; H, 8.96; N, 3.81.
ter t-Bu tyl (3′S,4R)-4-[3′-Meth yl-3′-(tr im eth ylsilyl)-1′,2′-
p r op a n ed ien yl]oxa zolid in e-3-ca r boxyla te (9a ). 1H NMR
(50 °C): δ 0.98 (s, 9H), 1.49 (s, 9H), 1.51 (s, 3H), 1.57 (s, 3H),
1.71 (d, J ) 7.8, 3H), 3.82-4.02 (m, 2H), 4.32-4.38 (m, 1H),
5.02-5.04 (m, 1H). 13C NMR (50 °C): δ -2.05, 15.25, 24.59,
26.77, 28.52, 55.50, 68.10, 79.64, 81.20, 85.82, 96.40, 151.79,
205.00. IR: 2983, 2873, 1936, 1693, 1453, 1383, 1095, 847. [R]23
D
Gen er a l P r oced u r e for t h e Syn t h esis of Sila b r om o-
a llen es 7. To a solution of dry LiBr (2.42 g, 27.9 mmol) and
CuBr‚Me2S (5.73 g, 27.9 mmol) in THF (126 mL) was added a
solution of the corresponding tosylate 6a or 6b (4.5 g, 9.3 mmol)
in THF (40 mL). After the solution was stirred at 60 °C for 6 h,
the reaction was quenched with a saturated solution of NH4Cl
and extracted with ether (3 × 50 mL). The organic layer was
washed with brine and dried. After evaporation of the solvent,
chromatography (hexane/ether 95/5) gave the final product as
a single diastereomer.
) +216 (c ) 3, EtOH). Anal. Calcd for C17H31NO3Si: C, 62.72;
H, 9.60; N, 4.31. Found: C, 62.98; H, 9.32; N, 4.51.
ter t-Bu t yl (3′S,4R)-4-[3′-Bu t yl-3′-(t r im et h ylsilyl)-1′,2′-
p r op a n ed ien yl]oxa zolid in e-3-ca r boxyla te (10a ). 1H NMR
(50 °C): δ 0.79-0.90 (m, 3H), 0.98 (s, 9H), 1.23-1.49 (m, 4H),
1.54 (s, 9H), 1.62 (s, 6H), 1.69-1.71 (m, 2H), 3.90-4.05 (m, 2H),
4.51-4.56 (m, 1H), 5.02-5.04 (m, 1H). [R]23 ) +188 (c ) 3,
D
EtOH). Anal. Calcd for C20H37NO3Si: C, 65.34; H, 10.12; N,
3.80. Found: C, 65.41; H, 10.01; N, 3.76.
Gen er a l P r oced u r e for th e P r ep a r a tion of Allen es 8 a n d
9 fr om Tosyla tes 6. To a solution of dry LiBr (5 equiv) and
CuBr‚Me2S (5 equiv) in THF was added at -30 °C the corre-
sponding phenyl or methyl Grignard reagent (5 equiv). The
mixture was stirred for 30 min at -30 °C. After the mixture
was cooled to -60 °C, a solution of tosylate 6a or 6b (1 equiv) in
THF was added. The reaction mixture was stirred for 10 min
at -60 °C before being allowed to warm to room temperature.
After being stirred for 1 h at room temperature, the mixture
was quenched with saturated NH4Cl, extracted with ether, and
dried. Chromatography (hexane/ether 90/10) gave the final
product as a single diastereomer. The physiscal data of com-
pounds 8a and 9a obtained from 6a are not reported again.
ter t-Bu tyl (3′R,4R)-4-[3′-P h en yl-3′-(tr im eth ylsilyl)-1′,2′-
p r op a n ed ien yl]oxa zolid in e-3-ca r boxyla te (8b). Yield: 76%,
oil. 1H NMR (50 °C): δ 0.26 (s, 9H), 1.45 (s, 9H), 1.52 (s, 3H),
1.60 (s, 3H), 3.92 (dd, J ) 2 and 8.7, 1H), 4.04 (dd, J ) 5.7 and
8.7, 1H), 4.49-4.55 (m, 1H), 5.39 (d, J ) 5.8, 1H), 7.17-7.35
(m, 5H). 13C NMR (50 °C): δ -0.3, 23.6, 27.2, 28.4, 55.7, 67.7,
81.2, 88.5, 93.7, 103.1, 126.3, 127.8, 128.4, 138.0, 152.9, 206.5.
ter t-Bu tyl (3′S,4R)-4-[3′-Br om o-3′-(tr im eth ylsilyl)-1′,2′-
p r op a n ed ien yl]oxa zolid in e-3-ca r boxyla te (7a ). Yield: 70%,
oil. 1H NMR: δ 0.15 (s, 9H), 1.46 (s, 9H), 1.56 (s, 3H), 1.61 (s,
3H), 4.06-4.28 (m, 2H), 4.89 (m, 1H), 5.11 (d, J ) 3.2, 1H). 13C
NMR: δ -0.4, 24.9, 26.3, 28.2, 61.9, 65.1, 80.8, 81.2, 95.0, 100.0,
152.4, 205.0. IR: 2985, 2937, 1958, 1705, 1477, 1369, 1091, 847.
MS: m/ z 390 (M+, 92), 334 (49), 312 (38), 290 (39), 254 (17),
200 (91). [R]23D ) +134 (c ) 5, EtOH). Anal. Calcd for C16H28
-
NO3Si: C, 49.23; H, 7.23; N, 3.59. Found: C, 49.00; H, 7.10; N,
3.69.
ter t-Bu tyl (3′R,4R)-4-[3′-Br om o-3′-(tr im eth ylsilyl)-1′,2′-
p r op a n ed ien yl]oxa zolid in e-3-ca r boxyla te (7b). Yield: 75%.
1H NMR: δ 0.12 (s, 9H), 1.43 (s, 3H), 1.46 (s, 9H), 1.60 (s, 3H),
4.01-4.26 (m, 3H), 5.19 (d, J ) 1.8, 1H). 13C NMR: δ -0.4,
24.8, 26.2, 28.2, 61.0, 65.0, 80.8, 81.2, 94.8, 101.0, 152.4, 205.1.
IR: 2985, 2937, 1958, 1705, 1477, 1369, 1091, 847. MS: m/ z
390 (M+, 55), 334 (35), 290 (23), 200 (100), 100 (84). [R]23
)
D
(13) Buckle, M. J . C.; Fleming, I. Tetrahedron Lett. 1993, 34, 2383.