1
912
D. C. Braddock et al.
LETTER
m/z 234 (M + NH ) , 217 (M + 1) ; HRMS (CI) calcd for
+
+
+
+
C H NO Si: (M + NH ) 280.1733; found: (M + NH ) ,
15
26
2
4
4
4
+
+
2
80.1730. Alcohol 11a: Colourless oil; R = 0.15 (CH Cl );
C H NSi: (M + NH ) 234.1678; found: (M + NH ) ,
f
2
2
14 24 4 4
–
1 1
IR: 3329(br) cm ; H NMR (270 MHz, CDCl ) 7.52 (m, 2
234.1675.
3
H), 7.35 (m, 3 H), 3.65 (dd, 1 H, J = 11.3, 6.5 Hz), 3.49 (dd,
(13) E.g., alcohol 11a displays an apparent quartet at = –0.13
H
1
1
H, J = 11.3, 8.3 Hz), 1.03 (m, 2 H), 0.90 (m, 1 H), 0.70 (dt,
ppm, (J = 5.1 Hz). This corresponds to one of the methylene
protons of the cyclopropane ring with a geminal coupling,
and two trans vicinal couplings (for cis relationships J >
7 Hz): syn isomer. See: Williams, D. H.; Fleming, I.
Spectroscopic Methods in Organic Chemistry; McGraw-
Hill: New York, 1995, 5th Ed.
H, J = 8.3, 4.6 Hz), 0.57 (dd, 1 H, J = 14.3, 9.9 Hz), 0.34
s, 3 H), 0.31 (s, 3 H), –0.13 (q, 1 H, J = 5.1 Hz); 1 C NMR
3
(
(
68 MHz; CDCl3) 139.2, 133.7, 129.0, 127.9, 63.2, 18.3,
+
14.2, 11.2, 11.1, –2.7, –3.1; MS (CI , NH ) m/z 238 (M +
3
+
+
NH ) , 203 (M + 1 – H O) ; HRMS (CI) calcd for
C H NOSi: (M + NH ) 238.1627; found: (M + NH ) ,
4
2
+
+
(14) General Procedure: TMSOTf (205 mg, 167 L, 0.92
mmol) was added dropwise to a stirring solution of
benzaldehyde dimethylacetal (140 mg, 0.92 mmol), and
vinylcyclopropane mix 6a and 6b (200 mg, 0.924 mmol),
and 2,6-di-tert-butylpyridine (250 L, 1.1 mmol) in CH Cl
13
24
4
4
238.1625. Alcohol 11b: Colourless oil; R = 0.11 (CH Cl );
f 2 2
–
1 1
IR: 3367(br) cm ; H NMR (270 MHz, CDCl ) 7.52 (m, 2
H), 7.34 (m, 3 H), 3.33 (m, 2 H), 0.76 (m, 3 H), 0.55 (m, 1
H), 0.33 (dt, 1 H, J = 8.2, 4.7 Hz), 0.31 (s, 3 H), 0.29 (s, 3 H),
3
2
2
1
3
0.22 (dt, 1 H, J = 7.9, 4.8 Hz); C NMR (68 MHz; CDCl3)
39.3, 133.6, 129.0, 127.9, 67.2, 23.1, 20.5, 12.5, 12.0,
(4.0 mL) at –78 °C. After the appropriate time (Table) the
1
reaction was quenched by addition of water (20 mL), and the
mixture was allowed to warm to room temperature. The
layers were separated and the aqueous layer was extracted
with CH Cl and washed with water. The combined organic
+
+
–2.60, –2.80; MS (CI , NH ) m/z 238 (M + NH ) ; HRMS
3
4
+
(
(
(
CI) calcd for C H NOSi: (M + NH ) 238.1627; found:
M + NH ) , 238.1627. Aldehyde 12a: Yellow oil; R = 0.36
1:1 CH Cl –petroleum ether, 40–60 °C); IR: 1703 cm ; H
13 24 4
+
4
f
2
2
–
1 1
layers were dried (MgSO ), and concentrated under vacuum
2
2
4
NMR (270 MHz, CDCl3) 9.39 (d, 1 H, J = 4.6 Hz), 7.50
to give a colourless oil (600 mg). Column chromatography
(3:7 CH Cl –petroleum ether 40–60 °C) yielded the skipped
(
(
m, 2 H), 7.35 (m, 3 H), 1.84 (m, 1 H), 1.46 (m, 1 H), 1.08
m, 4 H), 0.32 (s, 3 H), 0.30 (s, 3 H); C NMR (68 MHz;
2
2
1
3
–1
diene 13a (163 mg, 88%) as a colourless oil: IR: 1637 cm ;
1
CDCl3) 202.0, 138.3, 133.6, 129.2, 127.9, 28.2, 21.0, 16.3,
H NMR (270 MHz, CDCl3) 7.28 (m, 5 H), 5.75 (m, 1 H),
+
+
1
+
4.7, –2.9, –3.1; MS (CI , NH ) m/z 236 (M + NH ) , 219 (M
5.43 (m, 2 H), 4.92 (m, 2 H), 4.12 (t, 1 H, J = 6.6 Hz), 3.21
3
4
+
+
1) ; HRMS (CI) calcd for C H OSi: (M + H) 219.1205;
found: (M + H) , 219.1207. Aldehyde 12b: Yellow oil; R =
(s, 3 H), 2.70 (br t, 2 H, J = 5.7 Hz), 2.50 (m, 1 H), 2.38 (m,
1
3
19
+
1
1 H); H NMR (270 MHz, toluene-d ) 6.98 (m, 5 H), 5.72
f
8
0
.27 (1:1 CH Cl – etroleum ether, 40–60 °C); IR: 1706
(m, 1 H), 5.47 (dtt, 1 H, J = 15.3, 6.7, 1.2 Hz), 5.36 (ddt, 1
H, J = 15.3, 6.1, 1.2 Hz), 4.93 (m, 2 H), 3.98 (t, 1 H, J = 6.5
Hz), 3.05 (s, 3 H), 2.60 (br t, 2 H, J = 6.4 Hz), 2.53 (m, 1 H),
2
2
–
1 1
cm ; H NMR (270 MHz, CDCl ) 8.96 (d, 1 H, J = 5.3
Hz), 7.49 (m, 2 H), 7.35 (m, 3 H), 1.55 (m, 1 H), 1.41 (m, 1
H), 1.34 (m, 1 H), 1.00 (dd, 1 H, J = 6.0, 14.5 Hz), 0.85 (m,
3
1
3
2.32 (m, 1 H); C NMR (68 MHz; CDCl3) 142.0, 137.1,
130.4, 128.4, 127.6, 127.4, 126.8, 115.0, 84.1, 56.7, 41.4,
1
3
1
H), 0.72 (dd, 1 H, J = 14.5, 8.1 Hz), 0.31 (s, 3 H), 0.30 (s,
H); 13C NMR (68 MHz; CDCl3) 200.9, 138.3, 133.5,
36.8; MS (CI , NH ) m/z 203 (M + 1) .
+
+
3
+
1
29.2, 128.0, 32.6, 20.0, 19.3, 17.0, –2.9, –3.0,; MS (CI ,
(15) H NMR data for skipped diene products 13b–c, 13f–h.
+
+
1
NH ) m/z 236 (M + NH ) , 219 (M + 1) . HRMS (CI) calcd
for C H OSi: (M + H) 219.1205; found: (M + H) ,
Diene 13b: H NMR (270 MHz, CDCl ) 8.18 (d, 2 H, J =
3
4
+
3
+
8.8 Hz), 7.41 (d, 2 H, J = 8.8 Hz), 5.72 (m, 1 H), 5.37 (m, 2
H), 4.95 (m, 2 H), 4.24 (t, 2 H, J = 6.4 Hz), 3.23 (s, 3 H), 2.69
13
19
219.1205. Vinylcyclopropane 6a: Colourless oil; R = 0.86
f
–
1 1
(
1:1 CH Cl –petroleum ether, 40–60 °C); IR: 1632 cm ; H
(br t, 2 H, J = 5.3 Hz), 2.47 (1 H, m), 2.38 (1 H, m); Diene
2
2
1
NMR (270 MHz, CDCl3) 7.52 (m, 2 H), 7.35 (m, 3 H), 5.57
ddd, 1 H, J = 17.0, 10.3, 8.8 Hz), 5.07 (dd, 1 H, J = 17.0, 1.4
Hz), 4.98 (dd, 1 H, J = 10.3, 1.4 Hz), 1.44 (m, 1 H), 0.92 (m,
13c: H NMR (270 MHz, CDCl ) 9.97 (s, 1 H), 7.82 (d, 2
3
(
H, J = 8.3 Hz), 7.42 (d, 2 H, J = 8.3 Hz), 5.73 (ddt, 1 H, J =
16.0, 9.7, 6.5 Hz), 5.37 (m, 2 H), 4.95 (m, 2 H), 4.29 (t, 1 H,
J = 6.7 Hz), 3.34 (q, 2 H, J = 6.9 Hz), 2.67 (br t, 2 H, J = 6.5
3
1
1
H), 0.61 (dd, 1 H, J = 15.9, 10.2 Hz), 0.32 (s, 6 H), 0.15 (q,
1
3
H, J = 5.2 Hz); C NMR (68 MHz; CDCl3) 139.5, 138.7,
Hz), 2.47 (m, 1 H), 2.36 (m, 1 H), 1.16 (t, 3 H, J = 6.9 Hz);
1
33.7, 128.9, 127.7, 114.0, 20.3, 15.1, 14.4, 14.2, –2.7, –2.8;
Diene 13f: H NMR (270 MHz, CDCl ) 5.81 (ddt, 1 H, J =
3
+
+
+
MS (CI , NH ) m/z 234 (M + NH ) , 217 (M + 1) ; HRMS
16.4, 10.2, 6.2 Hz), 5.54 (m, 2 H), 5.03 (m, 2 H), 4.01 (dt, 1
H, J = 7.0, 1.8 Hz), 3.77 (m, 1 H), 3.43 (m, 1 H), 2.76 (br t,
3
4
+
(CI) calcd for C H NSi: (M + NH ) 234.1678; found: (M
1
4
24
4
+
+
NH ) , 234.1680. Vinylcyclopropane 6b: Colourless oil;
2 H, J = 5.6 Hz), 2.41 (m, 3 H), 1.20 (t, 3 H, J = 7.2 Hz);
4
1
R = 0.83 (1:1 CH Cl –petroleum ether 40–60 °C); IR: 1634
cm ; H NMR (270 MHz, CDCl ) 7.53 (m, 2 H), 7.36 (m,
Diene 13g: H NMR (270 MHz, CDCl ) 5.80 (ddt, 1 H,
f
2
2
3
–
1 1
J = 16.6, 10.2, 6.5 Hz), 5.47 (m, 2 H), 5.0 (m, 2 H), 3.39 (s,
3 H), 3.36 (m, 3 H), 3.34 (s, 3 H), 2.74 (br t, 2 H, J = 5.7 Hz),
3
3
H), 5.31 (ddd, 1 H, J = 17.1, 10.2, 8.7 Hz), 4.98 (dd, 1 H,
J = 17.1, 1.8 Hz), 4.82 (dd, 1 H, J = 10.2, 1.8 Hz), 1.07, (m,
H), 0.79 (m, 3 H), 0.60 (m, 1 H), 0.47 (m, 1 H), 0.33 (s, 6
1
2.24 (br t, 2 H, J = 5.7 Hz); Diene 13h: H NMR (270 MHz,
1
CDCl3) 5.80 (ddt, 1 H, J = 16.6, 10.2, 6.5 Hz), 5.53 (m, 1
H), 5.43 (m, 1 H), 5.00 (m, 2 H), 3.63–3.33 (m, 5 H), 2.75
(br t, 2 H, J = 6.2 Hz), 2.33 (m, 2 H), 1.20 (t, 1 H, J = 6.9 Hz).
13
H); C NMR (68 MHz; CDCl ) 142.1, 139.4, 133.7, 128.9,
3
+
127.7, 111.1, 24.5, 20.7, 16.6, 16.1, –2.7; MS (CI , NH )
3
Synlett 2001, No. 12, 1909–1912 ISSN 0936-5214 © Thieme Stuttgart · New York