9444
H.-T. Gao et al. / Tetrahedron 70 (2014) 9436e9448
1222, 1192, 1092, 1064, 1020, 989 cmꢀ1; 1H NMR (300 MHz, CDCl3):
113.7, 113.7, 74.5, 72.8, 60.6, 59.8, 55.2, 43.3, 36.2, 26.8, 22.5, 20.3,
15.9, 14.5, 10.5, 10.5 ppm; HRMS (ESI) m/z calcd for C23H32NaO4
395.2193, found for [MþNa]þ 395.2191.
d
6.98 (t, 1H, J¼7.1 Hz), 5.06 (t, 1H, J¼6.5 Hz), 4.91 (s, 1H), 4.62
(s, 1H), 4.46 (dd, 1H, J¼6.2, 10.4 Hz), 4.27 (dd, 1H, J¼1.2, 10.5 Hz),
3.96 (d, 1H, J¼11.7 Hz), 3.50 (dd, 1H, J¼3.3, 8.4 Hz), 3.18 (d, 1H,
J¼11.7 Hz), 2.57 (t, 2H, J¼6.5 Hz), 2.43 (d, 1H, J¼13.5 Hz), 1.97e2.02
(m, 3H), 1.79e1.87 (m, 2H), 1.72e1.77 (m, 2H), 1.42 (s, 3H), 1.37 (s,
3H), 1.24e1.33 (m, 3H), 1.20 (s, 3H), 0.97 (s, 3H) ppm; 13C NMR
Compound 18 was prepared analogously as for 7 in 72% yield
from 17a (E/Zz1:2 by 1H NMR) as a colorless oil.
(75 MHz, CDCl3):
d 170.6, 148.9, 146.8, 127.9, 108.9, 99.0, 76.2, 74.5,
65.7, 63.7, 55.8, 52.1, 38.2, 37.7, 37.5, 34.4, 27.0, 25.9, 25.2, 24.9, 24.8,
23.0, 15.9 ppm; HRMS (ESI) m/z calcd for C23H34NaO5 413.2298,
found for [MþNa]þ 413.2301.
Rf¼0.38 (petroleum ether/EtOAc¼10:1); IR (film): nmax 2956,
1513, 1249, 1115, 1091, 1036, 829 cmꢀ1; 1H NMR (300 MHz, CDCl3):
d
Compound 1 was prepared analogously as for 13 from com-
pound 16a in 89% yield as colorless plates.
7.48e7.52 (m, 2H), 7.30e7.40 (m, 3H), 7.26 (d, 2H, J¼8.1 Hz), 6.88
(d, 2H, J¼8.7 Hz), 5.09 (m, 1H), 4.94 (t, 1H, J¼6.3 Hz, CH (E)), 4.88 (t,
1H, J¼7.1 Hz, CH (Z)), 4.50 (d, 1H, J¼11.1 Hz), 4.45 (d, 1H, J¼11.7 Hz),
3.80 (s, 3H), 3.46 (d, 1H, J¼10.5 Hz), 3.39 (d, 1H, J¼11.1 Hz), 3.02 (t,
2H, J¼7.4 Hz, CH2I (Z)), 2.95 (t, 2H, J¼7.7 Hz, CH2I (E)), 2.82 (t, 1H,
J¼5.9 Hz), 2.53 (q, 2H, J¼6.9 Hz, CHCH2 (Z)), 2.37 (q, 2H, J¼7.2 Hz,
CHCH2 (E)), 1.97e2.17 (m, 5H), 1.86 (m, 2H), 1.58e1.73 (m, 6H), 1.55
(s, 3H), 1.31 (s, 3H), 0.30 (s, 6H) ppm; 13C NMR (75 MHz, CDCl3):
d
159.1, 139.3, 139.1, 134.4, 133.5, 133.4, 130.1, 129.3, 128.9, 127.7,
124.3, 122.1, 113.7, 74.4, 72.7, 60.7, 59.9, 55.2, 36.2, 32.7, 32.4, 32.2,
26.8, 26.7, 25.9, 21.2, 16.0, 14.5, 6.5, 6.1, e2.4, e2.8 ppm.
Rf¼0.11 (petroleum ether/EtOAc¼1: 2); mp 225ꢀ227 ꢁC, (Lit.2a
mp 217 ꢁC); [
a
]
20 ꢀ108 (c 0.4, MeOH), (Lit.2a
[
a
]
26 ꢀ126); IR (KBr):
D
D
nmax 3388, 3316, 2925, 1723, 1672, 1217, 1032, 979, 907 cmꢀ1
;
1H
NMR (300 MHz, DMSO-d6):
d
6.62 (t, 1H, J¼6.5 Hz), 5.71 (d, 1H,
J¼5.7 Hz), 5.04 (d, 1H, J¼4.8 Hz), 4.91 (t, 1H, J¼5.9 Hz), 4.81 (s, 1H),
4.63 (s, 1H), 4.39 (dd, 1H, J¼6.2, 9.8 Hz), 4.12 (dd, 1H, J¼2.6, 7.4 Hz),
4.04 (dd, 1H, J¼2.1, 9.9 Hz), 3.84 (dd, 1H, J¼2.7, 10.8 Hz), 3.20e3.26
(m, 2H), 2.32 (d, 1H, J¼12.3 Hz), 1.85e1.97 (m, 2H), 1.62e1.76 (m,
4H), 1.28e1.38 (m, 1H), 1.15e1.23 (m, 3H), 1.08 (s, 3H), 0.66 (s, 3H)
The stereochemistry confirmation and ratio of E/Z: The observed
positive NOE between Ha (4.94 ppm) and SiCH3 and the absence of
NOE between Hb (4.88 ppm) and SiCH3 indicated that Ha was on the
E double bond and Hb was on the Z double bond. So the ratio of E
and Z could be easily confirmed as ca. 1:2 by the integration of the
1H NMR signals at 4.94 ppm and 4.88 ppm.
ppm; 13C NMR (75 MHz, DMSO-d6):
d
169.9, 147.6, 146.3, 129.0,
108.3, 78.6, 74.3, 64.6, 62.7, 55.5, 54.4, 42.3, 38.6, 37.5, 36.5, 27.9,
24.0, 24.0, 23.1, 14.8 ppm; 1H NMR (300 MHz, C5D5N):
7.18 (t, 1H,
d
Compound 18a was obtained as minor by-product (ca. 2% yield
from 17a) as a colorless oil.
J¼6.6 Hz), 5.38 (br s, 1H), 4.96 (br s, 3H), 4.89 (s, 1H), 4.86 (s, 1H),
4.62 (dd, 1H, J¼5.7, 9.9 Hz), 4.52 (dd, 1H, J¼2.4, 9.9 Hz), 4.45 (d, 1H,
J¼10.5 Hz), 3.62e3.83 (m, 2H), 2.73 (t, 2H, J¼6.6 Hz), 2.34 (d, 1H,
J¼13.5 Hz), 1.78e2.03 (m, 4H), 1.69 (dd, 1H, J¼3.3, 12.9 Hz), 1.52
(s, 3H), 1.17e1.47 (m, 4H), 0.69 (s, 3H) ppm; 13C NMR (75 MHz,
C5D5N):
d 170.7, 148.0, 147.0, 130.2, 108.8, 79.9, 75.4, 66.0, 64.2,
56.4, 55.3, 43.3, 39.2, 38.2, 37.3, 29.0, 25.0, 24.4, 23.7, 15.2 ppm;
20
Rf¼0.42 (petroleum ether/EtOAc¼10:1); [
a
]
D
þ4.4 (c 0.43,
HRMS (ESI) m/z calcd for
C20H30NaO5 373.1985, found for
CHCl3); IR (film): nmax 2931, 1513, 1249, 1093, 1037, 877, 826 cmꢀ1
;
[MþNa]þ 373.1981. Spectroscopic and optical properties of syn-
thetic 1 are in complete agreement with those reported for natural
product.2a,4b,49
1H NMR (300 MHz, CDCl3):
d
7.26 (d, 2H, J¼8.1 Hz), 6.88 (d, 2H,
J¼8.7 Hz), 5.18 (t, 1H, J¼6.8 Hz), 4.62 (s, 2H), 4.51 (d, 1H, J¼11.1 Hz),
4.45 (d, 1H, J¼11.7 Hz), 3.81 (s, 3H), 3.47 (d, 1H, J¼10.5 Hz), 3.39 (d,
1H, J¼10.8 Hz), 2.84 (t, 1H, J¼6.3 Hz), 2.11e2.22 (m, 4H), 2.05 (q, 2H,
J¼7.3 Hz), 1.56e1.69 (m, 5H), 1.32 (s, 3H), 1.29 (m, 1H), 0.59e0.66
4.3. Synthesis of (D)-rostratone (25)
(m, 2H), 0.41e0.45 (m, 2H) ppm; 13C NMR (75 MHz, CDCl3):
d 159.2,
4.3.1. ((5E)-2-(3-Iodopropylidene)-8-((2S,3S)-3-(((4-methoxybenzyl)
oxy)methyl)-3-methyloxiran-2-yl)-6-methyloct-5-en-1-yl)dimethyl
(phenyl)silane (18). Compound 17a was prepared analogously as for
4 from compound 17 in 91% yield as a colorless oil.
150.7, 134.0, 130.2, 129.3, 124.8, 113.7, 106.1, 74.4, 72.7, 60.6, 59.9,
55.2, 36.2, 35.8, 26.8, 26.7, 16.0, 14.4, 5.99 ppm; EIMS m/z (%): 249
([Mꢀ121]þ, 0.88), 219 (1.03), 173 (0.51), 121(100).
4.3.2. (3R,4aS,6aR,7R,10aR,10bR)-7-(2-Iodoethyl)-3-(4-
methoxyphenyl)-6a,10b-dimethyl-8-methylenedecahydro-1H-naph-
tho[2,1-d][1,3]dioxine (20a) & (3R,4aS,6aR,7S,10aR,10bR)-7-(2-
io do et hyl) - 3 -( 4- m eth o xyp h enyl ) -6 a ,10 b- d im ethyl - 8-
m e t hyl e n e d e c a hy d r o - 1 H - n a p h t h o [ 2 ,1 - d ] [ 1, 3 ] d i o x i n e
(20b). Compound 19 was prepared analogously as for 8 (method-
A) from compound 18 in 70% isolated yield as a colorless oil of
20
Rf¼0.5 (petroleum ether/EtOAc¼3:1); [
a
]
ꢀ1.1 (c 2.2, CHCl3);
D
IR (film): nmax 2930, 1697, 1513, 1386, 1248, 1086, 1035, 821 cmꢀ1
;
1H NMR (300 MHz, CDCl3):
d
7.26 (d, 2H, J¼8.1 Hz), 6.88 (d, 2H,
a mixture of epimers at C-9 (9
a
/9b
¼1:1).
J¼8.1 Hz), 5.14 (t, 1H, J¼7.1 Hz), 4.50 (d, 1H, J¼11.1 Hz), 4.45 (d, 1H,
J¼12.0 Hz), 3.80 (s, 3H), 3.46 (d, 1H, J¼11.1 Hz), 3.39 (d, 1H,
J¼11.4 Hz), 2.83 (t, 1H, J¼6.2 Hz), 2.56 (t, 2H, J¼7.4 Hz), 2.29 (q, 2H,
J¼7.4 Hz), 2.03e2.21 (m, 2H), 1.86e1.94 (m, 1H), 1.61e1.68 (m, 5H),
1.31 (s, 3H), 0.98e1.02 (m, 2H), 0.81e0.87 (m, 2H) ppm; 13C NMR
(75 MHz, CDCl3):
d 210.5, 159.2, 135.1, 130.2, 129.2, 129.2, 123.5,