12
K. Mori, K. Akasaka / Tetrahedron xxx (2015) 1e14
stand overnight at room temperature. After conventional work-up,
200 mg (89%) of (R,R)-amide (35) was obtained as an oil, nmax
(film): 3301 (m), 2953 (s), 2923 (s), 2852 (s), 1653 (s), 1632 (s), 1600
(m), 1536 (s), 1465 (m), 1377 (m), 799 (w), 779 (m); dH (CDCl3): 0.83
(3H, d, J 6.4), 0.88 (3H, t, J 6.8), 1.00e1.10 (1H, m), 1.15e1.30 (26H, br
s), 1.67 (3H, d, J 6.8), 2.10e2.20 (2H, m), 5.64 (1H, d, J 7.2), 5.93 (1H,
m), 7.43e7.47 (1H, m), 7.50e7.54 (3H, m), 7.80 (1H, d, J 8.8), 7.86 (1H,
d, J 7.6), 8.09 (1H, d, J 8.0); GCeMS (same conditions as those for 4):
tR 28.28 min. Similarly, (S,R)-amide (35) was prepared from (S)-30.
Its 1H NMR spectrum was identical with that of (R,R)-35. (S,R)-35
showed tR 28.22 min in its GCeMS. Due to the no difference in 1H
NMR and GCeMS properties between (R,R)- and (S,R)-35, the en-
antiomeric purities of the enantiomers of 33 could not be
determined.
(5R,8RS,11R)-36]: tR 19.15 min (86.6%). HRMS calcd for C27H55
O
[(MeH)þ]: 395.4253, found: 395.4253.
4.21.3. (5S,8S or R,11R)-Isomer (crystals) and (5S,8R or S,11R)-isomer
(oil). Similarly, (S)-12 (2.40 g, 12.4 mmol) and (R)-30 (2.75 g,
9.8 mmol) gave 3.41 g [89% based on (R)-30] of (5S,8RS,11R)-36 as
a colorless oil, which solidified partially. Recrystallization from
acetone gave 775 mg (20%) of (5S,8S or, R,11R)-36 as fine rhombs,
mp 39e40 ꢁC. An analytical sample was obtained by further re-
23
crystallization from acetone, mp 42.5e43.0 ꢁC; [
a
]
D
þ0.71 (c 3.19,
hexane). Its IR, 1H NMR and MS spectra were identical with those of
the crystalline (5R,8R or S,11S)-36. GCeMS (same conditions as
those for (5R,8RS,11R)-36]: tR 19.13 min (100%). HRMS calcd for
C
27H55O [(MeH)þ]: 395.4253, found: 395.4242. Its mother liquor
(2.03 g, 53%) was obtained as a colorless oil of (5S,8R or S,11R)-36,
23
n2D1¼1.4568; [
a]
þ0.33 (c 4.56, hexane). Its IR, 1H NMR and MS
D
4.21. 5,11-Dimethyl-8-pentacosanol (36)
spectra were consistent with those of (5R,8RS,11R)-36. GCeMS
(same conditions as those for (5R,8RS,11R)-36]: tR 19.15 min (79.7%).
HRMS calcd for C27H55O [(MeH)þ]: 395.4253, found: 395.4253.
4.21.1. (5R,8RS,11R)-Isomer. A 3 mL-portion of a solution of (R)-12
(3.5 g, 18 mmol) in dry THF (15 mL) was added to Mg turnings
(528 mg, 22 mmol) and I2 (20 mg). The stirred mixture was heated
with a heat gun to initiate the reaction. The dark mixture soon
became colorless with brisk boiling. The rest of the bromide solu-
tion was added dropwise to the stirred mixture so as to maintain
the refluxing due to the exothermic reaction. After the addition, the
mixture was stirred and heated under reflux for 15 min. The stirred
mixture was then cooled in an ice-bath, and a solution of (R)-30
(4.0 g,14 mmol) in dry THF (10 mL) was added dropwise to it. When
the exothermic reaction ceased, the mixture was stirred and heated
at 50 ꢁC for 30 min, then cooled, acidified with ice and dil. HCl, and
extracted with Et2O. The Et2O solution was washed successively
with water, NaHCO3 solution and brine, dried (MgSO4), and con-
centrated in vacuo. The residue (6.70 g) was chromatographed over
SiO2 (70 g). Elution with hexane/EtOAc (30:1) gave 4.58 g [82%
4.21.4. (5S,8RS,11S)-Isomer. Similarly, (S)-12 (2.40 g, 12.4 mmol)
and (S)-30 (2.75 g, 9.8 mmol) gave 2.98 g [77% based on (S)-30] of
22
(5S,8RS,11S)-36 as a colorless oil, n2D1¼1.4572; [
a
]
D
þ0.81 (c 4.25,
hexane). Its IR, 1H NMR and MS spectra were identical with those of
(5R,8RS,11R)-36. GCeMS (same conditions as those for
(5R,8RS,11R)-36]: tR 19.15 min (81.5%). HRMS calcd for C27H55
O
[(MeH)þ]: 395.4253, found: 395.4251.
4.22. 8-Methanesulfonyloxy-5,11-dimethylpentacosane (37)
4.22.1. (5R,8RS,11R)-Isomer. A solution of MsCl (1.50 g, 13 mmol) in
dry CH2Cl2 (3 mL) was added to a stirred and ice-cooled solution of
(5R,8RS,11R)-36 (1.50 g, 3.8 mmol) and DMAP (20 mg) in dry C5H5N
(6 mL). The mixture was stirred for 1 h at 0e5 ꢁC, and left to stand
overnight in a refrigerator. It was then diluted with ice-water, and
extracted with Et2O. The Et2O solution was washed successively
with dil. HCl, NaHCO3 solution and brine, dried (MgSO4), and
concentrated in vacuo to give 1.85 g (quant.) of (5R,8RS,11R)-37 as
a colorless oil, nmax (film): 2955 (s), 2925 (s), 2854 (s), 1465 (m),
1377 (m), 1359 (m), 1176 (s), 903 (s), 532 (m). This was employed in
the next step without further purification.
based on (R)-30] of (5R,8RS,11R)-36 as a colorless oil, which solid-
20
ified in a deep freezer, n2D0¼1.4572; [
a]
ꢀ0.66 (c 4.56, hexane);
D
nmax (film): 3346 (m), 2955 (s), 2925 (s), 2854 (s), 1465 (m), 1377
(m), 1040 (m), 721 (m); dH (CDCl3): 0.80e0.90 (12H, m), 1.07e1.15
(2H, m), 1.15e1.50 (43H, m), 3.50e3.60 (1H, m); GCeMS [column:
HP-5MS, 5% phenylmethylsiloxane, 0.25 mm i.d.ꢂ30 m; carrier gas,
He; press:52.8 kPa; temp: 50 ꢁC (2 min) ꢀ300 ꢁC (þ15 ꢁC/min)]: tR
19.15 min (88.6%); MS (EI, 70 eV): m/z: 378 (10) [(MꢀH2O)þ], 297
(8), 283 (69), 238 (39), 223 (22), 210 (14), 197 (6), 181 (13), 157 (12),
143 (60), 125 (56), 111 (50), 97 (76), 83 (92), 69 (100), 57 (88), 55
(54), 43 (50), 41 (32). HRMS calcd for C27H55O [(MꢀH)þ]: 395.4253,
found: 395.4242.
4.22.2. (5R,8RS,11S)-Isomer. Similarly, 1.08 g (2.7 mmol) of crystal-
line (5R,8R or S,11S)-36 gave 1.19 g (92%) of (5R,8R or S,11S)-37 as an
oil, and 1.50 g (3.8 mmol) of oily (5R,8S or R,11S)-36 gave 1.81 g
(quant.) of (5R,8S or R,11R)-37 as a slightly yellowish oil. Their IR
spectra were consistent with that of (5R,8RS,11R)-37.
4.21.2. (5R,8R or S, 11S)-Isomer (crystals) and (5R,8S or R, 11S)-iso-
mer (oil). Similarly, (R)-12 (3.50 g, 18 mmol) and (S)-30 (4.01 g,
14 mmol) gave 4.86 g [87% based on (S)-30] of (5R,8RS,11S)-36 as
a colorless oil, which solidified partially. Recrystallization of the
solid from acetone gave (5R,8R or S, 11S)-36 (1.4g, 25%) as rhombs,
4.22.3. (5S,8RS,11R)-Isomer. Similarly, 710 mg (1.8 mmol) of crys-
talline (5S,8S or R,11R)-36 gave 770 mg (90%) of (5S,8S or R,11R)-37
as an oil, and 1.50 g (3.8 mmol) of oily (5S,8R or S,11R)-36 gave
1.80 g (quant.) of (5S,8R or S,11R)-37 as a slightly yellowish oil. Their
IR spectra were consistent with that of (5R,8RS,11R)-37.
mp 41.5e42.0 ꢁC. An analytical sample was obtained by further
24
recrystallization from acetone, mp 43.5e44.0 ꢁC; [
a
]
ꢀ0.71 (c
D
2.84, hexane); nmax (Nujol): 3310 (m), 3219 (m), 1295 (w), 1233 (w),
1154 (w), 1130 (w), 1085 (w), 1056 (m), 976 (w), 939 (w), 918 (w),
881 (m), 846 (w), 763 (w), 719 (m); dC (CDCl3): 14.09, 14.13, 14.15,
19.62, 19.75, 22.69, 23.01, 27.02, 29.25, 29.36, 29.65, 29.69, 30.00,
31.92, 32.85, 32.88, 34.85, 36.57, 36.88, 72.89. Its 1H NMR and MS
spectra were virtually identical with those of (5R,8RS,11R)-36.
GCeMS [same conditions as those for (5R,8RS,11R)-36]: tR 19.14 min
(100%). HRMS calcd for C27H55O [(MeH)þ]: 395.4253, found;
395.4247. Its mother liquor (2.70 g, 48%) was obtained as a colorless
4.22.4. (5S,8RS,11S)-Isomer. Similarly, 1.50
g
(3.8 mmol) of
(5S,8RS,11S)-36 gave 1.81 g (quant.) of (5S,8RS,11S)-37 as a slightly
yellowish oil. Its IR spectrum was identical with that of
(5R,8RS,11R)-37.
4.23. 5,11-Dimethylpentacosane (1)
4.23.1. (5R,11R)-Isomer. A solution of (5R,8RS,11R)-37 (1.85 g,
3.8 mmol) in dry THF (5 mL) was added dropwise to a stirred and
ice-cooled suspension of LiAlH4 (350 mg, 9 mmol) in dry THF
(15 mL). After the addition, the mixture was stirred and heated
under reflux for 1 h. After cooling, the excess LiAlH4 was destroyed
oil of (5R,8S or R, 11S)-36, n2D0¼1.4573; [
a]
24 ꢀ0.38 (c 6.29, hexane).
D
Its IR, 1H NMR and MS spectra were indistinguishable from those of
(5R,8RS,11R)-36. GCeMS (same conditions as those for