S.-S. Ng, T. F. Jamison / Tetrahedron 61 (2005) 11405–11417
11413
olefin geometry was determined to be Z by a NOE
experiment (see below). H NMR (500 MHz, CDCl3, d):
Ni(cod)2, NHC-iPr and triethylsilane in THF following the
standard procedure B described above afforded 3c in 74%
yield as a colorless oil and 95% ee as determined by chiral
HPLC. The absolute configuration of the stereocenter was
assigned as R in analogy to 3a and 3j whose configuration
were established by Mosher’s ester analysis. 1H NMR
(500 MHz, CDCl3, d): 7.24 (d, JZ7.9 Hz, 2H), 7.11 (d, JZ
7.6 Hz, 2H), 5.74 (s, 1H), 5.22 (t, JZ7.0 Hz, 1H), 2.34 (s,
3H), 2.27 (q, JZ7.3 Hz, 2H), 2.03 (m, 1H), 1.74 (m, 1H),
1.50 (sextet, JZ7.3 Hz, 2H), 1.38–1.18 (m, 4H), 1.00 (t, JZ
7.3 Hz, 3H), 0.97 (t, JZ7.9 Hz, 9H), 0.82 (t, JZ7.0 Hz,
3H), 0.63 (q, JZ7.9 Hz, 6H); 13C NMR (125 MHz, CDCl3,
d): 142.0, 141.5, 136.0, 128.7, 125.6, 125.1, 71.2, 31.0, 30.3,
29.6, 23.6, 22.9, 21.3, 14.33, 14.28, 7.1, 5.1; IR (NaCl, thin
film): 2957, 2875, 1458, 1073, 1006, 741; HRMS-ESI (m/z):
[MCNa]C calcd for C23H40OSi, 383.274; found, 383.275;
[a]2D0 K83.8 (c 1.05, CHCl3); Chiral HPLC analysis:
analysis was performed on the corresponding free alcohol,
obtained by the deprotection of 3c (TBAF, THF): (Chiralcel
OD, hexanes: 2-propanol, 100:0, 1.5 mL/min): tR(R)Z
37.7 min; tR(S)Z49.1 min.
1
7.16–7.40 (m, 5H), 5.76 (s, 1H), 5.24 (t, JZ7.3 Hz, 1H),
2.27 (q, JZ7.5 Hz, 2H), 2.02 (m, 1H), 1.74 (m, 1H), 1.51
(sextet, JZ7.5 Hz, 2H), 1.14–1.34 (m, 4H), 1.01 (t, JZ
6.7 Hz, 3H), 0.97 (t, JZ7.6 Hz, 9H), 0.81 (t, JZ7.0 Hz,
3H), 0.64 (q, JZ7.9 Hz), 13C NMR (100 MHz, CDCl3, d):
144.5, 141.9, 128.0, 126.5, 125.6, 125.4, 71. 3, 31.0, 30.4,
29.6, 23.6, 22.9, 14.34, 14.26, 7.11, 7.07; IR (NaCl, thin
film): 2957, 2875, 1458, 1063, 742, 698; HRMS-ESI (m/z):
[MCNa]C calcd for C22H38OSi, 369.258; found, 369.259;
[a]2D0 K75.2 (c 1.07, CHCl3); Chiral HPLC analysis:
analysis was performed on the corresponding free alcohol,
obtained by the deprotection of 3a (TBAF, THF): (Chiralcel
OD, hexanes: 2-propanol, 99:1, 1.0 mL/min): tR(S)Z
9.7 min; tR(R)Z10.8 min.
Mosher’s ester analysis: (C/K)-3a was first converted into
the free alcohol (TBAF, THF) and was then converted into a
pair of diastereomers of (R)-Mosher’s esters (DCC, DMAP,
(R)-Mosher’s acid, CH2Cl2).25 The vinyl triplets (d 5.45 and
5.51 ppm) of the two diastereomers were well resolved by
1H NMR and were assigned according to the method of
Mosher.24 The enantiomerically-enriched 3a was then
converted to (R)-Mosher’s ester using the same procedure.25
The vinyl triplet was observed at d 5.46 ppm. Therefore, 3a
had an absolute configuration of (R).
7.3.6. 2-Butyl-1-(4-methoxy-phenyl)-hex-2-enyloxy]-
triethyl-silane (3d). The reaction of (aS)-nona-4,5-diene
(2a) (82 mL, 0.5 mmol) and p-anisaldehyde (183 mL,
1.5 mmol) with Ni(cod)2, NHC-iPr and triethylsilane in
THF following the standard procedure B described above
afforded 3d in 75% yield as a colorless oil and 95% ee as
determined by chiral HPLC. The absolute configuration of
the stereocenter was assigned as R in analogy to 3a and 3j
whose configuration were established by Mosher’s ester
analysis. 1H NMR (400 MHz, CDCl3, d): 7.28 (d, JZ
8.8 Hz, 2H), 6.87 (d, JZ8.4 Hz, 2H), 5.73 (s, 1H), 5.23 (t,
JZ7.2 Hz, 1H), 3.82 (s, 3H), 2.26 (q, JZ7.6 Hz, 2H), 2.05
(m, 1H), 1.76 (m, 1H), 1.50 (sextet, JZ7.2 Hz, 2H), 1.40–
1.15 (m, 4H), 1.01 (t, JZ7.2 Hz, 3H), 0.98 (t, JZ8.0 Hz,
9H), 0.84 (t, JZ7.0, 3H), 0.64 (q, JZ7.6 Hz, 6H); 13C NMR
(100 MHz, CDCl3, d): 158.3, 142.1, 136.7, 126.7, 125.1,
113.4, 71.0, 55.4, 31.0, 30.3, 29.6, 23.6, 22.9, 14.33, 14.28,
7.1, 5.1; IR (NaCl, thin film): 2956, 2875, 1510, 1464, 1246,
1071, 741; [a]2D0 K67.5 (c 1.14, CHCl3); Chiral HPLC
analysis: analysis was performed on the corresponding free
alcohol, obtained by the deprotection of 3d (TBAF, THF):
(Chiralcel OD, hexanes: 2-propanol, 99:1, 1.0 mL/min):
tR(R)Z14.3 min; tR(S)Z17.0 min.
NOE DIFF experiment: pre-saturation of the carbinol proton
of 3a gave no NOE to the vinylic proton (d 5.24 ppm), but
13% NOE was observed for the allylic protons indicated
(d 2.27 ppm). These results supported a Z olefin geometry.
7.3.4. (2-Butyl-1-o-tolyl-hex-2-enyloxy)-triethyl-silane
(3b). The reaction of (aS)-nona-4,5-diene (2a) (82 mL,
0.5 mmol) and o-tolualdehyde (174 mL, 1.5 mmol) with
Ni(cod)2, NHC-iPr and triethylsilane in THF following the
standard procedure B described above afforded 3b in 66%
yield as a colorless oil and 95% ee as determined by chiral
HPLC. The absolute configuration of the stereocenter was
assigned as R in analogy to 3a and 3j whose configurations
were established by Mosher’s ester analysis. 1H NMR
(400 MHz, CDCl3, d): 7.71 (br d, JZ7.6 Hz, 1H), 7.21 (bt,
JZ7.4 Hz, 1H), 7.13 (dt, JZ1.4, 7.4 Hz, 1H), 7.04 (br d,
JZ7.4 Hz, 1H), 5.75 (s, 1H), 5.20 (t, JZ6.6 Hz, 1H), 2.38–
2.22 (dq, JZ7.5, 14.8 Hz, 2H), 2.20 (s, 3H), 1.91 (ddt, JZ
1.1, 5.4, 10.32 Hz, 1H), 1.65 (ddt, JZ1.0, 6.7, 9.8 Hz, 1H),
1.49 (sextet, JZ6.9 Hz, 2H), 1.16 (m, 3H), 1.03 (t, JZ
5.6 Hz, 4H), 0.94 (t, JZ8.0 Hz, 9H), 0.77 (t, JZ7.1 Hz,
3H), 0.60 (q, JZ7.5 Hz, 6H), 13C NMR (100 MHz, CDCl3,
d): 142.2, 139.1, 134.2, 129.8, 126.9, 126.7, 126.5, 125.6,
69.1, 31.7, 30.6, 30.5, 23.5, 22.8, 19.6, 14.4, 14.2, 7.1, 5.2;
IR (NaCl, thin film): 2957, 2875, 1462, 1061, 1006, 744;
HRMS-ESI (m/z): [MCNa]C calcd for C23H40OSi,
383.274; found, 383.274; [a]2D0 K75.2 (c 1.25, CHCl3);
Chiral HPLC analysis: analysis was performed on the
corresponding free alcohol, obtained by the deprotection of
3b (TBAF, THF): (Chiralcel OD, hexanes: 2-propanol,
99:1, 1.0 mL/min): tR(S)Z11.4 min; tR(R)Z14.1 min.
7.3.7. 4-(2-Butyl-1-triethylsilanyloxy-hex-2-enyl)-ben-
zoic acid methyl ester (3e). The reaction of (aS)-nona-
4,5-diene (2a) (82 mL, 0.5 mmol) and methyl 4-formyl-
benzoate (246 mL, 1.5 mmol) with Ni(cod)2, NHC-iPr and
triethylsilane in THF following the standard procedure B
described above afforded 3e in 56% yield (co-eluted with a
small amount of homoallylic alcohol minor products) as a
colorless oil and 95% ee as determined by chiral HPLC. The
absolute configuration of the stereocenter was assigned as R
in analogy to 3a and 3j whose configuration were
established by Mosher’s ester analysis. 1H NMR
(500 MHz, CDCl3, d): 7.98 (d, JZ7.5 Hz, 2H), 7.43 (d,
JZ8.0 Hz, 2H), 5.79 (s, 1H), 5.26 (t, JZ7.0 Hz, 1H), 3.90
(s, 3H), 2.28 (q, JZ7.1 Hz, 2H), 1.95 (m, 1H), 1.72 (m, 1H),
1.55 (sextet, JZ7.0 Hz, 2H), 1.30–1.10 (m, 4H), 1.01 (t, JZ
7.0 Hz, 3H), 0.96 (t, JZ7.6 Hz, 9H), 0.79 (t, JZ7.3 Hz,
3H), 0.63 (q, JZ7.9 Hz, 6H); 13C NMR (125 MHz, CDCl3,
7.3.5. (2-Butyl-1-p-tolyl-hex-2-enyloxy)-triethyl-silane
(3c). The reaction of (aS)-nona-4,5-diene (2a) (82 mL,
0.5 mmol) and p-tolualdehyde (177 mL, 1.5 mmol) with