LETTER
4), 49.2 (C-6), 51.6 (OMe), 121.4 (C-2), 148.9 (C-3), 167.1
Formation of Four- to Six-Membered Carbocycles
707
(C-3), 51.3 (C-1), 51.5 (OMe), 86.2 (C-2), 125.9, 126.7,
127.9, and 145.8 (Ar), 174.4 (C = O). HRMS calcd for
(CO2Me), 246.8 (SiC = O). 14c: a colorless oil, Rf (hexane :
AcOEt = 5:1) = 0.46. IR (film) 1725, 1655, 1640 cm-1. 1H
NMR (500 MHz, CDCl3) d 0.14 (6H, s, SiMe2), 0.88 (9H, s, t-
Bu), 2.34-2.39 (2 H, m, H-4), 2.70 (2 H, t, J = 7.3 Hz, H-5),
3.66 (3 H, s, OMe), 5.77 (1 H, dt, J = 15.6, 1.7 Hz, H-2), 6.88
(1 H, dt, J = 15.6, 7.1 Hz, H-3). 13C NMR (125 MHz, CDCl3)
d -6.93 (SiMe2), 16.6 (CMe3), 24.6 (C-4), 26.5 (CMe3), 48.2
(C-5), 51.6 (OMe), 121.4 (C-2), 148.4 (C-3), 167.0 (CO2Me),
244.9 (SiC = O). HRMS calcd for C13H24O3Si 256.1495,
found 256.1479.
C20H32O3Si 348.2121, found 348.2152. 17b: a colorless oil, Rf
(hexane : AcOEt = 10:1) = 0.46. IR (film) 1740 cm-1. 1H
NMR (500 MHz, CDCl3) d -0.41 and –0.08 (each 3 H, s,
SiMe2), 0.86 (9H, s, t-Bu), 1.35-1.43 (1 H, m, H-5), 1.61 (1 H,
dd, J = 15.2, 11.5 Hz, CH2CO2Me), 1.82-1.88 (1 H, m, H-4),
1.91-1.99 (1 H, m, H-4), 2.02 (1 H, dd, J = 15.2, 3.6 Hz,
CH2CO2Me), 2.04-2.10 (1 H, m, H-3), 2.14-2.21 (1 H, m, H-
5), 2.22-2.28 (1 H, m, H-3), 2.65-2.70 (1 H, m, H-1), 3.57 (3
H, s, OMe), 7.22-7.32 (3 H, m, Ar-H), 7.36-7.38 (2 H, m, Ar-
H). 13C NMR (125 MHz, CDCl3) d -3.21 and –2.61 (SiMe2),
18.4 (CMe3), 21.0 (C-4), 26.1 (CMe3), 28.5 (C-5), 35.2 (C-3),
36.8 (CH2CO2Me), 48.9 (C-1), 51.6 (OMe), 87.1 (C-2), 127.5,
128.1, and 143.6 (Ar), 173.8 (C = O). HRMS calcd for
C20H32O3Si 348.2121, found 348.2091. 16c: a colorless oil, Rf
(hexane : AcOEt = 10:1) = 0.46. IR (film) 1740 cm-1. 1H
NMR (500 MHz, CDCl3) d -0.46, -0.06 (each 3 H, s, SiMe2),
0.84 (9H, s, t-Bu), 1.61-1.68 (1 H, m, H-4), 1.85-1.93 (1 H, m,
H-4), 2.27-2.33 (1 H, m, H-3), 2.59 (1 H, dd, J = 15.6, 7.5 Hz,
CH2CO2Me), 2.74-2.85 (2 H, m, H-1 and H-3), 2.88 (1 H, dd,
J = 15.6, 7.5 Hz, CH2CO2Me), 3.67 (3 H, s, OMe), 7.23-7.27
(1 H, m, Ar-H), 7.31-7.35 (2 H, m, Ar-H), 7.45-7.47 (2 H, m,
Ar-H). 13C NMR (125 MHz, CDCl3) d -3.42 and –2.83
(SiMe2), 18.3 (CMe3), 20.1 (C-4), 26.0 (CMe3), 31.9 (C-3),
35.3 (CH2CO2Me), 45.5 (C-1), 51.5 (OMe), 78.6 (C-2), 126.3,
127.3, 128.2, and 146.5 (Ar), 174.0 (C = O). HRMS calcd for
C15H21O3Si (M+- t-Bu) 277.1260, found 277.1254. 17c: a
colorless oil, Rf (hexane : AcOEt = 15:1) = 0.32. IR (film)
1740 cm-1. 1H NMR (500 MHz, CDCl3) d -0.24 and –0.02
(each 3 H, s, SiMe2), 0.90 (9H, s, t-Bu), 1.28-1.36 (1 H, m, H-
4), 1.50 (1 H, dd, J = 15.6, 10.7 Hz, CH2CO2Me), 2.05-2.12 (1
H, m, H-4), 2.16 (1 H, dd, J = 15.6, 4.9 Hz, CH2CO2Me),
2.31-2.38 (1 H, m, H-3), 2.68-2.72 (1 H, m, H-3), 2.94-3.01 (1
H, m, H-1), 3.57 (3 H, s, OMe), 7.24-7.27 (1 H, m, Ph), 7.32-
7.35 (2 H, m, Ar-H), 7.38-7.41 (2 H, m, Ar-H). 13C NMR (125
MHz, CDCl3) d -2.81 and –2.67 (SiMe2), 18.2 (CMe3), 20.1
(C-4), 26.1 (CMe3), 34.1 (C-3), 36.7 (CH2CO2Me), 46.5 (C-
1), 51.5 (OMe), 79.7 (C-2), 126.6, 127.3, 128.1, and 142.7
(Ar), 173.3 (C = O). HRMS calcd for C15H21O3Si (M+- tBu)
277.1260, found 277.1259.
(10) Miller, J. A.; Zweifel, G. Synthesis 1981, 288-289.
(11) Yoshizaki, H.; Tanaka, T.; Yoshii, E.; Koizumi, T.; Takeda,
K. Tetrahedron Lett. 1998, 39, 47-50.
(12) General procedure for the tandem Brook rearrangement-
Michael reaction using phenyllithium. Reaction of 14a with
phenyllithium. To a cooled (-80 °C) solution of 14a (142 mg,
0.50 mmol) in THF (50 mL) was added phenyllithium (1.07 M
in cyclohexane-Et2O, 514 mL, 0.550 mmol). The solution was
stirred at the same temperature for 30 min, and then allowed
to warm to –30 °C before the addition of AcOH (32 mL, 0.550
mmol) in THF (2 mL). The reaction mixture was diluted with
saturated NH4Cl solution (20 mL), and then extracted with
Et2O (50 mL x 1, 10 mL x 2). Combined organic phases were
washed with saturated brine (20 mL), dried (MgSO4), and
concentrated. The residual oil was subjected to column
chromatography (silica gel, 15 g; elution with 10:1
hexane:AcOEt) to give a 1.6:1 mixture of 16a and 17a (142
mg, 79%), which could be separated by medium pressure
liquid chromatography (10 m silica gel). 16a a colorless oil, Rf
(hexane : AcOEt = 15:1) = 0.32. IR (film) 1740 cm-1. 1H
NMR (500 MHz, CDCl3) d -0.16 and 0.08 (each 3 H, s,
SiMe2), 0.99 (9H, s, t-Bu), 1.35-1.44 (1 H, m, H-5), 1.45-1.55
(2 H, m, H-6), 1.58-1.64 (1 H, m, H-4), 1.69-1.74 (1 H, m, H-
5), 1.76-1.81 (1 H, m, H-4), 1.88 (1 H, dm, J = 12.2 Hz, H-3),
2.15-2.23 (3 H, m, H-1, H-3, and CH2CO2Me), 2.42 (1 H, d,
J = 12.2 Hz, CH2CO2Me), 3.53 (3 H, s, OMe), 7.20-7.31 (3 H,
m, Ar-H), 7.46-7.48 (2 H, m, Ar-H). 13C NMR (125 MHz,
CDCl3) d -1.65 and –0.89 (SiMe2), 19.5 (CMe3), 22.7 (C-4),
24.7 (C-5), 26.7 (CMe3), 28.0 (C-6), 35.3 (CH2CO2Me), 37.5
(C-3), 45.0 (C-1), 51.5 (OMe), 79.1 (C-2), 126.7, 126.9, 127.8
and 146.3 (Ar), 174.5 (C = O). HRMS calcd for C17H25O3Si
(M+- t-Bu) 305.1573, found 305.1575. 17a: a colorless oil, Rf
(hexane : AcOEt = 10:1) = 0.46. IR (film) 1740 cm-1. 1H
NMR (500 MHz, CDCl3) d -0.10 (6H, s, SiMe2), 0.90 (9H, s,
t-Bu), 1.36-1.59 (3 H, m, H-3 and H-4), 1.62-1.68 (1 H, m, H-
5), 1.73 (1 H, ddd, J = 15.4, 3.5, 0.9 Hz, CH2CO2Me), 1.77-
1.86 (1 H, m, H-5), 1.94 (1 H, ddd, J = 13.4, 13.4, 3.8 Hz, H-
6), 2.00 (1 H, dm, J = 13.4 Hz, H-6), 2.17 (1 H, dd, J = 15.4,
11.2 Hz, CH2CO2Me), 2.14-2.22 (1 H, m, H-3), 2.63-2.68 (1
H, m, H-1), 3.52 (3 H, s, OMe), 7.22-7.32 (3 H, m, Ar-H), 7.42
(2 H, d, J = 7.32 Hz, Ar-H). 13C NMR (125 MHz, CDCl3) d -
3.35 and –2.17 (SiMe2), 18.8 (CMe3), 19.9 (C-4), 21.8 (C-5),
25.3 (C-3), 26.3 (CMe3), 31.3 (C-6), 34.2 (CH2CO2Me), 42.9
(C-1), 51.6 (OMe), 76.8 (C-2), 126.6, 127.5, 128.2, and 146.0
(Ar), 173.8 (C = O). HRMS calcd for C21H34O3Si 362.2277,
found 362.2271. 16b: a colorless oil, Rf (hexane :
(13) General procedure for the tandem Brook rearrangement-
Michael reaction using lithium dimethyl phosphite. Reaction
of 14a with lithium dimethyl phosphite. To a cooled (-80 °C)
solution of dimethyl phosphite (50 mL, 0.550 mmol) in THF
(2.6 mL) was added n-butyllithium (1.33 M in hexane, 0.41
mL, 0.550 mmol). After being stirred at the same temperature
for 15 min, the mixture was added to a cooled (-80 °C)
solution of 14a (142 mg, 0.500 mmol) in THF (50 mL). The
solution was stirred at the same temperature for 30 min, and
then allowed to warm to –30 °C before the addition of AcOH
(32 mL, 0.550 mmol) in THF (2 mL). The reaction mixture
was diluted with saturated NH4Cl solution (20 mL), and then
extracted with Et2O (50 mL x 1, 10 mL x 2). Combined
organic phases were washed with saturated brine (20 mL),
dried (MgSO4), and concentrated. The residual oil was
subjected to column chromatography (silica gel, 15 g; elution
with 1:2 hexane:AcOEt) to give a 2.0:1 mixture of 20a and
21a (137 mg, 69%), which could be separated by medium
pressure liquid chromatography (10 m silica gel). 20a: a
colorless oil, Rf (hexane : AcOEt = 1:2) = 0.32. IR (film) 1735
cm-1. 1H NMR (500 MHz, CDCl3) d 0.15 (6H, s, SiMe2), 0.91
(9H, s, t-Bu), 1.24-1.32 (1 H, m, H-5), 1.35-1.44 (1 H, m, H-
6), 1.46-1.60 (3 H, m, H-4 and H-6), 1.62-1.69 (2 H, m, H-3
and H-5), 2.04-2.08 (1 H, m, H-3), 2.15 (1 H, dd, J = 16.2,
10.1 Hz, CH2CO2Me), 2.20-2.25 (1 H, m, H-1), 3.16 (1 H, dd,
J = 16.2, 2.6 Hz, CH2CO2Me), 3.64 (3 H, s, CO2Me), 3.72 (3
AcOEt = 15:1) = 0.32. IR (film) 1740 cm-1. 1H NMR (500
MHz, CDCl3) d -0.14 and 0.08 (each 3 H, s, SiMe2), 0.98 (9H,
s, t-Bu), 1.54-1.62 (1 H, m, H-5), 1.81-1.94 (2 H, m, H-4),
1.95-2.02 (1 H, m, H-5), 2.10 (1 H, ddddd, J = 9.4, 4.7, 4.7,
4.7, 4.7 Hz, H-3), 2.15-2.12 (1 H, m, H-1), 2.31 (1 H, dd,
J = 15.6, 10.0 Hz, CH2CO2Me), 2.42 (1 H, dd, J = 15.6, 4.1
Hz, CH2CO2Me), 2.41-2.48 (1 H, m, H-3), 3.53 (3 H, s, OMe),
7.19-7.32 (3 H, m, Ar-H), 7.42-7.45 (2 H, m, Ar-H). 13C NMR
(125 MHz, CDCl3) d -2.58 and –2.27 (SiMe2), 19.1 (CMe3),
21.9 (C-4), 26.5 (CMe3), 30.3 (C-5), 33.5 (CH2CO2Me), 39.4
Synlett 1999, No. 6, 705–708 ISSN 0936-5214 © Thieme Stuttgart · New York