LETTER
4.61 (br dd, J = 3.3, 6.0 Hz, 1 H), 4.36 (q, J = 7.8 Hz, 0.9 H),
Stereoselective 1,4-Phenyl Migration in Cyclic Acetals
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1 H), 3.65 (ddd, J = 12.3, 11.1, 2.4 Hz, 1 H), 2.17–2.02 (m,
2 H), 1.92–1.78 (m, 1 H), 1.72 (d, J = 5.4 Hz, 1 H), 1.48–
1.42 (m, 1 H). 13C NMR (75 MHz, CDCl3): d = 139.64,
128.49, 127.52, 125.81, 81.18, 68.96, 68.01, 30.25, 19.92.
IR (neat): 3454, 2947, 2849, 1958, 1887, 1813, 1451, 1267,
1216, 1091, 1057, 1003, 725, 699 cm–1.
4.31 (q, J = 8.1 Hz, 0.1 H), 4.05 (dt, J = 4.8, 7.8 Hz, 0.9 H),
4.03–3.97 (m, 0.1 H), 2.29–2.14 (m, 2 H), 0.88 (s, 8.1 H),
0.81 (s, 0.9 H). 13C NMR (75 MHz, CDCl3): d = 140.84,
138.17, 135.42, 130.95, 129.95, 129.84, 128.35, 128.27,
128.19, 127.87, 127.80, 127.60, 127.54, 127.43, 127.04,
126.94, 125.66, 88.56, 85.42, 74.82, 74.59, 66.99, 66.84,
64.79, 64.50, 36.76, 36.58, 26.10, 26.00, 19.00, 18.70. IR
(neat): 3068, 3032, 2934, 2862, 1951, 1895, 1810, 1723,
1669, 1605, 1593, 1495, 1475, 1456, 1431, 1064 cm–1. Anal.
Calcd for C27H32O3Si: C, 74.96; H, 7.46. Found: C, 74.91; H,
7.20.
Compound 13 (63% dr by 1H NMR analysis): 1H NMR (300
MHz, CDCl3): d = 7.76–7.65 (m, 4.14 H), 7.50–7.21 (m,
14.6 H), 7.11–7.07 (m, 1.26 H), 4.86 (s, 0.63 H), 4.63–4.58
(m, 0.37 H), 4.62 (d, J = 12.0 Hz, 0.63 H), 4.59 (d, J = 11.7
Hz, 0.37 H), 4.57 (d, J = 11.7 Hz, 0.37 H), 4.54 (d, J = 12.0
Hz, 0.63 H), 4.51 (d, J = 11.7 Hz, 0.37 H), 4.46 (d, J = 11.7
Hz, 0.37 H), 4.39 (dt, J = 6.3, 3.9 Hz, 0.37 H), 4.35–4.27 (m,
1.63 H), 4.20 (d, J = 12.3 Hz, 0.63 H), 4.18 (d, J = 3.9 Hz,
0.37 H), 3.95 (d, J = 12.3 Hz, 0.63 H), 3.82 (br dd, J = 5.1,
1.2 Hz, 0.63 H), 3.74 (dd, J = 10.2, 5.1 Hz, 0.63 H), 3.70 (dd,
J = 10.2, 6.9 Hz, 0.63 H), 3.66 (dd, J = 10.5, 3.9 Hz, 0.37 H),
3.51 (dd, J = 10.5, 6.3 Hz, 0.37 H), 3.24 (s, 1.11 H), 3.23 (s,
1.89 H), 1.12 (s, 3.33 H), 1.09 (s, 5.67 H). 13C NMR (75
MHz, CDCl3): d = 138.38, 138.25, 138.28, 138.07, 136.08,
135.90, 134.87, 133.80, 133.40, 133.22, 133.15, 130.08,
129.85, 129.79, 128.38, 128.32, 128.24, 127.91, 127.83,
127.70, 127.62, 127.56, 127.49, 127.44, 110.49, 101.59,
83.54, 83.46, 81.02, 79.96, 78.01, 75.55, 73.54, 73.48,
73.27, 71.49, 69.90, 69.68, 26.98, 26.95, 19.22. IR (neat):
3072, 3034, 2934, 2862, 1963, 1891, 1827, 1473, 1456,
1429, 1112, 1060, 822, 739, 700 cm–1. Anal. Calcd for
C36H42O5Si: C, 74.19; H, 7.26. Found: C, 74.38; H, 7.36.
Compound 14 (81% dr at Si by 1H NMR analysis): 1H NMR
(300 MHz, CDCl3): d = 7.56 (d, J = 1.5 Hz, 0.19 H), 7.54 (d,
J = 1.5 Hz, 0.19 H), 7.47–7.12 (m, 18 H), 6.98 (d, J = 1.5 Hz,
0.81 H), 6.95 (d, J = 1.5 Hz, 0.81 H), 5.22 (d, J = 3.0 Hz,
0.19 H), 5.20 (d, J = 3.0 Hz, 0.81 H), 4.76 (dt, J = 3.6, 6.0
Hz, 1 H), 4.70 (d, J = 12.0 Hz, 0.81 H), 4.68 (d, J = 12.0 Hz,
0.19 H), 4.57 (d, J = 12.0 Hz, 0.81 H), 4.56 (d, J = 12.0 Hz,
0.81 H), 4.55 (d, J = 12.0 Hz, 0.19 H), 4.45 (d, J = 12.0 Hz,
0.81 H), 4.42 (dd, J = 3.3, 0.9 Hz, 0.19 H), 4.36 (dd, J = 2.7,
1.2 Hz, 0.81 H), 4.33 (d, J = 12.0 Hz, 0.19 H), 4.21 (d,
J = 12.0 Hz, 0.19 H), 4.18 (dd, J = 3.6, 1.2 Hz, 0.81 H), 4.05
(dd, J = 3.6, 1.2 Hz, 0.19 H), 3.85 (dd, J = 9.9, 6.0 Hz, 0.81
H), 3.81 (dd, J = 9.9, 6.0 Hz, 0.81 H), 3.78 (d, J = 6.0 Hz,
0.38 H), 3.47 (s, 2.43 H), 3.07 (s, 0.57 H), 0.79 (s, 7.29 H),
0.77 (s, 1.71 H). 13C NMR (75 MHz, CDCl3): d = 138.38,
138.04, 137.54, 135.37, 130.55, 130.13, 129.90, 128.43,
128.15, 128.07, 127.98, 127.93, 127.78, 127.62, 127.57,
127.48, 127.35, 85.32, 85.09, 83.44, 80.04, 79.75, 77.17,
73.69, 72.31, 69.08, 51.96, 26.21, 25.97, 18.62. IR (neat):
3068, 3032, 2934, 2862, 1953, 1890, 1810, 1087 cm–1. Anal.
Calcd for C36H42O5Si: C, 74.19; H, 7.26. Found: C, 74.09; H,
7.09.
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Compound 3a (>95% dr by 1H NMR analysis): [a]D
+130.3 (c 1.40, CHCl3). 1H NMR (300 MHz, CDCl3):
d = 7.43–7.27 (m, 5 H), 4.90 (d, J = 3.6 Hz, 1 H), 4.41 (br s,
1 H), 4.27 (q, J = 8.7 Hz, 1 H), 4.03 (dt, J = 4.2, 8.7 Hz, 1 H),
2.28 (ddt, J = 13.2, 4.2, 8.7 Hz, 1 H), 2.15 (dddd, J = 13.2,
8.7, 4.2, 1.5 Hz, 1 H), 1.19 (s, 1 H). 13C NMR (75 MHz,
CDCl3): d = 136.97, 128.66, 127.99, 126.80, 85.14, 73.72,
67.07, 34.93. IR (neat): 3392, 3066, 3032, 2928, 2884, 1957,
1895, 1820, 1493, 1454, 1125, 1083, 1060, 1029, 739, 700
cm–1. ESI-HRMS: m/z calcd for C10H12O2Na: 187.0729;
found: 187.0734.
Compound 6 (93% dr at Si by 1H NMR analysis): 1H NMR
(300 MHz, CDCl3): d = 7.51–7.47 (m, 0.2 H), 7.43–7.27 (m,
10.8 H), 7.20–7.14 (m, 2 H), 6.96–6.92 (m, 2 H), 5.10 (d,
J = 4.8 Hz, 0.07 H), 5.04 (d, J = 4.2 Hz, 0.93 H), 4.90 (d,
J = 13.2 Hz, 0.93 H), 4.84 (d, J = 13.2 Hz, 0.93 H), 4.64 (d,
J = 13.5 Hz, 0.07 H), 4.56 (d, J = 13.5 Hz, 0.07 H), 4.37 (d,
J = 4.8 Hz, 0.07 H), 4.18 (d, J = 4.8 Hz, 0.93 H), 3.98 (d,
J = 7.8 Hz, 0.93 H), 3.91 (d, J = 7.8 Hz, 0.07 H), 3.62 (d,
J = 7.8 Hz, 0.93 H), 3.56 (d, J = 7.8 Hz, 0.07 H), 1.23 (s,
2.79 H), 1.15 (s, 2.79 H), 1.02 (s, 0.42 H), 0.86 (s, 8.37 H),
0.75 (s, 0.63 H). 13C NMR (75 MHz, CDCl3): d = 140.77,
138.54, 135.42, 131.11, 129.69, 129.08, 128.36, 127.90,
127.64, 127.51, 127.07, 125.86, 85.66, 81.97, 79.11, 65.39,
44.94, 26.52, 26.05, 21.02, 19.11. IR (neat): 3068, 3032,
2966, 2862, 1949, 1870, 1810, 1740, 1607, 1593, 1473,
1456, 1065, 733, 698 cm–1. ESI-HRMS: m/z calcd for
C29H36O3NaSi: 483.2331; found: 483.2310.
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Compound 7 (>95% dr by 1H NMR analysis): H NMR (300
MHz, CDCl3): d = 7.42–7.27 (m, 5 H), 5.30 (d, J = 3.6 Hz, 1
H), 3.96 (d, J = 7.5 Hz, 1 H), 3.80 (br t, J = 3.0 Hz, 1 H), 3.72
(d, J = 7.5 Hz, 1 H), 1.21 (s, 3 H), 1.15 (s, 3 H), 1.07 (br s, 1
H). 13C NMR (75 MHz, CDCl3): d = 137.80, 128.69, 127.88,
126.73, 84.48, 80.61, 79.01, 44.21, 25.82, 19.41. IR (neat):
3342, 2960, 1950, 1900, 1830, 1466, 1309, 1096, 1038, 739,
700 cm–1. Anal. Calcd for C12H16O2: C, 74.97; H, 8.39.
Found: C, 74.86; H, 8.16.
Compound 11 (90% dr at Si by 1H NMR analysis): 1H NMR
(300 MHz, CDCl3): d = 7.63–7.61 (m, 0.3 H), 7.48–7.13 (m,
10.7 H), 7.17 (t, J = 7.5 Hz, 2 H), 6.99 (t, J = 7.5 Hz, 2 H),
4.76 (d, J = 13.5 Hz, 1 H), 4.65 (d, J = 13.5 Hz, 1 H), 4.43
(s, 1 H), 4.27–4.22 (m, 1 H), 4.09 (s, 1 H), 3.90–3.80 (m, 0.1
H), 3.66 (dt, J = 2.6, 12.6 Hz, 0.9 H), 2.42–2.00 (m, 2 H),
1.84–1.73 (m, 1 H), 1.40 (br d, J = 13.5 Hz, 1 H), 0.95 (s, 8.1
H), 0.83 (s, 0.9 H). 13C NMR (75 MHz, CDCl3): d = 141.02,
140.79, 135.89, 135.47, 135.39, 131.20, 129.59, 128.28,
128.17, 127.99, 127.88, 127.62, 127.51, 127.41, 127.28,
127.17, 126.93, 126.78, 126.73, 125.63, 82.58, 69.80, 69.55,
68.87, 68.77, 64.63, 31.34, 26.37, 26.31, 20.26, 19.04. IR
(neat): 2930, 2856, 1961, 1898, 1808, 1453, 1115, 1098,
1071, 1026 cm–1. ESI-HRMS: m/z calcd for C28H34O3NaSi:
469.2169; found: 469.2159.
Compound 15 (>95% dr by 1H NMR analysis): [a]D24 –63.2
(c 1.07, CHCl3). 1H NMR (300 MHz, CDCl3): d = 7.40–7.28
(m, 15 H), 5.33 (d, J = 3.3 Hz, 1 H), 4.72 (d, J = 12.0 Hz, 1
H), 4.69 (d, J = 12.3 Hz, 1 H), 4.67 (ddd, J = 6.6, 5.7, 4.2 Hz,
1 H), 4.65 (d, J = 12.0 Hz, 1 H), 4,57 (d, J = 12.3 Hz, 1 H),
4.27 (br s, 1 H), 4.17 (br dd, J = 4.2, 1.2 Hz, 1 H), 3.84 (dd,
J = 9.9, 5.7 Hz, 1 H), 3.80 (dd, J = 9.9, 6.6 Hz, 1 H), 1.27 (br
s, 1 H). 13C NMR (75 MHz, CDCl3): d = 138.41, 138.05,
136.36, 128.74, 128.53, 128.43, 128.14, 127.86, 127.64,
127.57, 126.83, 84.19, 83.01, 80.21, 76.45, 73.56, 72.70,
68.88. IR (neat): 3432, 3066, 3032, 2924, 2870, 1955, 1883,
1814, 1497, 1456, 1083, 737, 698 cm–1. ESI-HRMS: m/z
calcd for C25H26O4Na: 413.1723; found: 413.1707.
(9) Benzyl acetal 1b was prepared from cyclic hemiacetal 1a
and benzyl alcohol in the presence of a catalytic amount of
PPTS.
Compound 12 (>95% dr by 1H NMR analysis): 1H NMR
(300 MHz, CDCl3): d = 7.38–7.25 (m, 5 H), 4.50 (d, J = 1.2
Hz, 1 H), 4.18 (ddt, J = 11.1, 4.5, 1.8 Hz, 1 H), 3.94–3.91 (m,
Synlett 2008, No. 13, 2064–2068 © Thieme Stuttgart · New York