10736 J. Am. Chem. Soc., Vol. 121, No. 46, 1999
Trost and Ariza
2 (1.8 mg, 4.9 µmol), and 1 (10.4 mg, 15.1 µmol) in 2 mL of toluene
after stirring at room temperature for 24 h and flash chromatographic
purification (93:7 pet ether-ethyl acetate) gave azlactone 17 (51.0 mg,
66% yield), [R]D ) -41.2 (c ) 1.04, CH2Cl2). Enantiomeric excess
was determined by chiral HPLC (Chiralcel OD column, heptane-2-
propanol, 99.9:0.1), tR(-) ) 11.2, tR(+) ) 12.5.
µmol), and 1 (4.0 mg, 5.8 µmol) in 1.5 mL of toluene gave, after 3 h
at room temperature and flash chromatography (95:5 petroleum ether-
ethyl acetate), azlactone 24 (452.4 mg, 88% yield), [R]D ) -34.1 (c
) 1.01, CH2Cl2). Enantiomeric excess was determined by chiral HPLC
(Chiralcel OD column, heptane-2-propanol, 99.5:0.5) tR(-) ) 5.4, tR-
(+) ) 7.8.
(E)-4-Methyl-4-(4-methyl-2-pentenyl)-2-phenyl-2-oxazolin-5-
one (24): IR(neat film from CH2Cl2) 1823, 1655, 1602, 1581, 1494,
1451, 1321 cm-1. 1H NMR (300 MHz, CDCl3) δ 8.00-7.97 (m, 2H),
7.57 (m, 1H), 7.51-7.45 (m, 2H), 5.54 (dd, J ) 15.4, 6.8 Hz, 1H),
5.21 (dt, J ) 15.4, 7.4 Hz, 1H), 2.59-2.46 (AB system, 2H), 2.16 (m,
1H), 1.52 (s, 3H), 0.85 (d, J ) 6.6 Hz, 3H), 0.84 (d, J ) 6.6 Hz, 3H).
13C NMR (75.5 MHz, CDCl3) δ 180.6, 159.7, 144.3, 132.7, 128.8,
127.9, 126.1, 119.0, 70.2, 41.1, 30.9, 22.9, 22.3, 22.1. Anal. Calcd for
C16H19NO2: C, 74.68, H, 7.44, N, 5.44. Found: C, 74.68, H, 7.20, N,
5.20.
Alkylations with 3-Acetoxy-3-trimethylsilylpropene (25). 4-Ben-
zyl-2-phenyl-2-oxazolin-5-one: Following the general procedure, 3-ace-
toxy-3-trimethylsilylpropene (25, 34.5 mg, 200 µmol), triethylamine
(56 µL, 400 µmol), 4a (113.1 mg, 450 µmol), 2 (1.8 mg, 4.9 µmol),
and 1 (10.4 mg, 15.1 µmol) in 2 mL of toluene gave, after 24 h at
room temperature and flash chromatography (95:5 pet ether-ethyl
acetate), the silylated azlactone 26a (50.3 mg, 69%), [R]D ) -53.7 (c
) 1.05, CH2Cl2), and desilylated azlactone 5a (16.8 mg, 27% including
catalyst). Enantiomeric excess was determined by chiral HPLC (Chiral-
cel OD column, heptane-2-propanol, 99.9:0.1), tR(-) ) 13.4, tR(+)
) 18.9.
(E)-4-Benzyl-2-phenyl-4-(3-trimethylsilyl-2-propenyl)-2-oxazolin-
5-one (26a): IR (neat film from CDCl3) 1818, 1655, 1605, 1581, 1496,
1452, 1321 cm-1. 1H NMR (300 MHz, CDCl3) δ 7.89-7.86 (m, 2H),
7.54 (m, 1H), 7.46-7.41 (m, 2H), 7.22-7.16 (m, 5H), 6.19 (dt, J )
14.2, 7.4 Hz, 1H), 5.70 (d, J ) 14.2 Hz, 1H), 3.26 (d, J ) 13.3 Hz,
1H), 3.17 (d, J ) 13.3 Hz, 1H), 2.82 (dd, J ) 7.4, 1.2 Hz, 2H), 0.16
(s, 9H). 13C NMR (75.5 MHz, CDCl3) δ 179.3, 159.9, 139.3, 135.3,
134.4, 132.6, 130.3, 128.7, 128.2, 127.9, 127.3, 125.8, 74.2, 43.2, 40.3,
0.0. Anal. Calcd for C22H25NO2Si: C, 72.69, H, 6.93, N, 3.85. Found:
C, 72.77, H, 7.02, N, 3.90.
4-Benzyl-4-geranyl-2-phenyl-2-oxazolin-5-one (17). IR (neat film
from CDCl3) 1817, 1656, 1603, 1581, 1496, 1452, 1376, 1321 cm-1
.
1H NMR (300 MHz, CDCl3) δ 7.85-7.82 (m, 2H), 7.51 (m, 1H), 7.43-
7.38 (m, 2H), 7.20-7.12 (m, 5H), 5.06 (t, J ) 7.6 Hz, 1H), 4.96 (m,
1H), 3.25 (d, J ) 13.4 Hz, 1H), 3.17 (d, J ) 13.4 Hz, 1H), 2.75 (dd,
J ) 14.0, 8.2 Hz, 1H), 2.67 (dd, J ) 14.0, 7.1 Hz, 1H), 1.96-1.88 (m,
4H), 1.65 (s, 3H), 1.58 (s, 3H), 1.47 (s, 3H). 13C NMR (75.5 MHz,
CDCl3) δ 179.7, 159.8, 141.3, 134.7, 132.4, 131.6, 130.2, 128.7, 128.2,
127.8, 127.1, 125.9, 123.9, 116.1, 75.3, 43.0, 39.7, 35.9, 26.5, 25.5,
17.4, 16.4. Anal. Calcd for C26H29NO2: C, 80.59, H, 7.54, N, 3.61.
Found: C, 80.71, H, 7.38, N, 3.61.
Alkylation of 4-Benzyl-2-phenyl-2-oxazolin-5-one with 3-Acetoxy-
1,1-diphenylpropene (18). Following the general procedure, 3-acetoxy-
1,1-diphenylpropene (18, 50.5 mg, 200 µmol), triethylamine (56 µL,
400 µmol), 4a (113.1 mg, 450 µmol), 2 (1.8 mg, 4.9 µmol), and 1
(10.4 mg, 15.1 µmol) in 2 mL of toluene gave after 3 days at room
temperature and flash chromatographic purification (95:5 pet ether:
ethyl acetate), (6.7 mg, 13% recovery) recovered starting material 18,
and azlactone 19 (73.9 mg, 84% yield, 96% yield brsm), [R]D ) -70.7
(c ) 0.93, CH2Cl2). Enantiomeric excess was determined by chiral
HPLC (Chiralpak AD column, heptane 2-propanol 99:1), tR(-) ) 9.5,
tR(+) ) 11.6.
4-Benzyl-4-(3,3-diphenyl-2-propenyl)-2-phenyl-2-oxazolin-5-
one (19): IR (neat film from CDCl3) 1816, 1655, 1601, 1580, 1495,
1452, 1321 cm-1. 1H NMR (300 MHz, CDCl3) δ 7.88-7.85 (m, 2H),
7.54-7.49 (m, 1H), 7.44-7.34 (m, 5H), 7.23-7.11 (m, 12H), 6.03 (t,
J ) 7.4 Hz, 1H), 3.19 (d, J ) 13.4 Hz, 1H), 3.10 (d, J ) 13.4 Hz,
1H), 2.85-2.83 (m, 2H). 13C NMR (75.5 MHz, CDCl3) δ 179.3, 160.0,
146.2, 142.2, 139.4, 134.4, 132.6, 130.2, 130.0, 128.7, 128.4, 128.2,
127.9, 127.5, 127.4, 127.2, 125.7, 120.9, 74.6, 42.9, 37.4. Anal. Calcd
for C31H25NO2: C, 83.95, H, 5.68, N, 3.16. Found: C, 84.09, H, 5.49,
N, 3.16.
Alkylation of 4-Methyl-2-phenyl-2-oxazolin-5-one with 3-Ace-
toxy-3-phenyl-1-butene (20). Following the general procedure, 3-ace-
toxy-3-phenyl-1-butene (20, 38 µL, 200 µmol), triethylamine (56 µL,
400 µmol), 4b (78.8 mg, 450 µmol), 2 (1.8 mg, 4.9 µmol), and 1 (10.4
mg, 15.1 µmol) in 2 mL of toluene gave, after 3 h at room temperature
and flash chromatography (96:4 pet ether:ethyl acetate), azlactone 21
(28.5 mg, 47% yield) [R]D ) -5.0 (c ) 0.53, CH2Cl2) followed by
azlactone 22 (25.3 mg, 41% yield), [R]D ) +3.7 (c ) 2.13, CH2Cl2).
Enantiomeric excess was determined by chiral HPLC (Chiralcel OD
column heptane:2-propanol 99.1:0.1), tR(+) ) 11.3, tR(-) ) 19.5 for
21; tR(-) ) 23.6, tR(+) ) 31.1 for 22.
4-Methyl-2-phenyl-2-oxazolin-5-one. Following the general pro-
cedure, 3-acetoxy-3-trimethylsilylpropene (25, 172.5 mg, 1.0 mmol),
triethylamine (280 µL, 2.0 mmol), 4b (394.0 mg, 2.25 mmol), 2 (9.0
mg, 24.5 µmol), and 1 (51.8 mg, 75.5 µmol) in 10 mL of toluene gave,
after 22 h at room temperature and flash chromatography (97:3 pet
ether-ethyl acetate), in order of elution 27b (56.9 mg, 20% yield),
26b (151.4 mg, 53% yield), Z-isomer of 26b (19.2 mg, 3% yield), and
5c (27.0 mg, 7% yield).
(E)-4-Methyl-2-phenyl-4-(3-trimethylsilyl-2-propenyl)-2-oxazolin-
5-one (26b): Oil. Enantiomeric excess was determined by chiral HPLC
(Chiralcel OD column, heptane-2-propanol, 99.9: 0.1), tR(-) ) 10.4,
tR(+) ) 13.0. IR(neat film from CH2Cl2) 1821, 1655, 1610, 1581, 1452,
1
(Z)-4-Methyl-4-(3-phenyl-2-butenyl)-2-phenyl-2-oxazolin-5-one (21):
1321 cm-1. H NMR (300 MHz, CDCl3) δ 8.01-7.98 (m, 2H), 7.57
IR(neat film from CH2Cl2) 1820, 1654, 1601, 1580, 1493, 1451, 1374,
(m, 1H), 7.51-7.46 (m, 2H), 6.14 (dt, J ) 14.2, 7.3 Hz, 1H), 5.68 (d,
J ) 14.2 Hz, 1H), 2.69 (d, J ) 7.3 Hz, 2H), 1.54 (s, 3H), 0.14 (s, 9H).
13C NMR (75.5 MHz, CDCl3) δ 180.4, 159.9, 139.5, 135.2, 132.7,
128.8, 128.0, 126.0, 69.2, 41.2, 23.2, 0.0. Anal. Calcd for C16H21NO2-
Si: C, 66.86, H, 7.36, N, 4.87. Found: C, 66.71, H, 7.12, N, 4.85.
(Z)-4-Methyl-2-phenyl-4-(3-trimethylsilyl-2-propenyl)-2-oxazolin-
5-one (Z-isomer of 26b): Oil. Enantiomeric excess was determined
by chiral HPLC (Chiralcel OD column, heptane-2-propanol, 99.5: 0.5),
tR(-) ) 5.9, tR(+) ) 7.0. IR (neat film from CDCl3) 1821, 1655, 1617,
1
1321 cm-1. H NMR (300 MHz, CDCl3) δ 8.03-8.00 (m, 2H), 7.57
(m, 1H), 7.52-7.46 (m, 2H), 7.37-7.32 (m, 2H), 7.26 (m, 1H), 7.19-
7.16 (m, 2H), 5.37 (tq, J ) 7.3, 1.3 Hz, 1H), 2.54 (d, J ) 7.3 Hz, 2H),
1.98 (d, J ) 1.3 Hz, 3H), 1.44 (s, 3H). 13C NMR (75.5 MHz, CDCl3)
δ 180.9, 159.8, 141.9, 141.4, 132.7, 128.8, 128.3, 128.0, 127.9, 126.9,
126.1, 118.9, 69.5, 37.5, 25.9, 23.0. Anal. Calcd for C20H19NO2: C,
78.66, H, 6.27, N, 4.59. Found: C, 78.65, H, 6.22, N, 4.54.
(E)-4-Methyl-4-(3-phenyl-2-butenyl)-2-phenyl-2-oxazolin-5-one
(22): IR (neat film from CH2Cl2) 1820, 1655, 1601, 1581, 1494, 1451,
1381, 1321 cm-1. 1H NMR (300 MHz, CDCl3) δ 8.00-7.97 (m, 2H),
7.56 (m, 1H), 7.50-7.44 (m, 2H), 7.25-7.18 (m, 5H), 5.63 (tq, J )
7.7, 1.4 Hz, 1H), 2.79 (d, J ) 7.7 Hz, 2H), 2.06 (d, J ) 1.4 Hz, 3H),
1.60 (s, 3H). 13C NMR (75.5 MHz, CDCl3) δ 180.7, 160.0, 143.6, 140.4,
132.7, 128.9, 128.2, 128.0 (2), 127.1, 125.9, 119.9, 70.1, 37.3, 23.2,
16.3. Anal. Calcd for C20H19NO2: C, 78.66, H, 6.27, N, 4.59. Found:
C, 78.70, H, 6.43, N, 4.47.
1
1581, 1494, 1452, 1321 cm-1. H NMR (300 MHz, CDCl3) δ 7.98-
7.95 (m, 2H), 7.56 (m, 1H), 7.50-7.44 (m, 2H), 5.84-5.82 (m, 2H),
2.64-2.62 (AB system, 2H), 1.52 (s, 3H), -0.09 (s, 9H). 13C NMR
(75.5 MHz, CDCl3) δ 180.5, 159.8, 138.3, 137.8, 132.7, 128.8, 127.9,
126.0, 69.8, 45.0, 22.9, -1.7. Anal. Calcd for C16H21NO2Si: C, 66.86,
H, 7.36, N, 4.87. Found: C, 67.01, H, 7.30, N, 4.80.
4-Allyl-4-methyl-2-phenyl-2-oxazolin-5-one (5c): Oil. Enantiomeric
excess was determined by chiral HPLC (Chiralcel OD column,
heptane-2-propanol, 99.9: 0.1), tR(-) ) 11.7, tR(+) ) 22.8. IR (neat
film from CDCl3) 1819, 1655, 1581, 1493, 1451, 1321 cm-1. 1H NMR
(300 MHz, CDCl3) δ 8.00-7.97 (m, 2H), 7.57 (m, 1H), 7.51-7.45
(m, 2H), 5.68 (m, 1H), 5.20-5.10 (m, 2H), 2.68-2.54 (AB system,
Alkylation of 4-Methyl-2-phenyl-2-oxazolin-5-one with (E)-1-
Acetoxy-4-methyl-2-pentene (23). Following the general procedure,
(E)-1-acetoxy-4-methyl-2-pentene (23, 284.4 mg, 2.0 mmol), triethyl-
amine (280 µL, 2.0 mmol), 4b (350.2 mg, 2.0 mmol), 2 (0.7 mg, 1.9