Journal of Asian Natural Products Research
947
added dropwise, and the reaction mixture
was stirred for 2 h at this temperature. The
resulting solution was then cooled to
purified by flash chromatography on silica
gel, eluting with light petroleum ether–
ethyl acetate mixture (10:1 v/v) to afford 4
2
0
2
908C. 18 was dissolved in dry CH Cl2
2
(573 mg, 80%) as a yellow oil. [a]
D
1
2105.1 (c 0.28, CHCl ); H NMR
(10 ml) and added dropwise to the reaction
3
mixture. The reaction mixture was stirred
at 2908C for 3 h and quenched by the
addition of a saturated aqueous solution of
(600 MHz, CDCl ) d (ppm) 7.77 (d,
3
J ¼ 7.8 Hz, 2H, ArH), 7.57 (d,
J ¼ 7.2 Hz, 2H, ArH), 7.18–7.40 (m,
24H, ArH), 5.86 (m, 1H, CH), 5.48–5.67
(m, 1H, CHv), 5.29–5.48 (m, 2H, CHv,
NH Cl. The reaction mixture was then
4
allowed to warm to room temperature and
extracted three times with CH Cl
CH), 4.17–4.40 (m, 4H, CH , 2CH),
2
2
2
(
50 ml £3). The combined organic layers
3.49–3.69 (m, 2H, CH ), 3.42 (m, 1H,
2
were dried over Na SO , filtered, and the
2
CHHS), 3.18 (m, 1H, CHHS), 2.97 (t,
J ¼ 10.8 Hz, 1H, PhCHH), 2.84 (d,
J ¼ 10.8 Hz, 1H, PhCHH), 2.17 (m, 2H,
CH ), 2.08 (m, 2H, CH ), 0.87 (d,
4
solvent evaporated under reduced pressure.
The resulting crude was purified by flash
chromatography on silica gel, eluting with
light petroleum ether–ethyl acetate mix-
ture (15:1 v/v) to afford 7 (1.82 g, 75%) as
2
2
J ¼ 6.6 Hz, 3H, (CH ) CH), 0.80 (d,
3
2
1
3
J ¼ 6.6 Hz, 3H, (CH ) CH); C NMR
3
2
2
0
a yellow oil. [a] 2 105.1 (c 0.28,
1
CHCl ); H NMR (300 MHz, CDCl ) d
(150 MHz, CDCl ) d (ppm) 200.7, 172.8,
3
D
156.3, 143.9, 143.8, 141.3, 136.1, 129.5,
129.4, 128.9, 127.9, 127.8, 127.6, 127.3,
127.1, 125.1, 120.0, 67.9, 67.1, 57.0,
47.2, 40.2, 37.3, 32.3, 30.3, 22.6, 19.4,
19.2, 15.2.
3
3
(
ppm) 7.17–7.41 (m, 20H, ArH), 5.56–
.63 (m, 1H, CHOH), 5.47 (dd, J ¼ 5.7,
5
1
5.6 Hz, 1H, CHv), 5.32–5.39 (m, 1H,
CHv), 4.59 (m, 1H, CH), 3.56 (dd,
J ¼ 5.1, 14.4 Hz, 1H, CHH), 3.28–3.37
(
m, 2H, CHH, CHHS), 3.20 (dd, J ¼ 5.1,
3.14 Liner precursor (2)
1
4.4 Hz, 1H, CHHS), 2.91–3.07 (m, 1H,
PhCHH), 2.86 (d, J ¼ 11.4 Hz, PhCHH),
3 (105 mg, 0.32 mmol) was dissolved in
dry DMF (5 ml) and treated with DMAP
(70 mg, 0.57 mmol). After stirring for
30 min, 4 in dry DMF (5 ml) was added
to the mixture dropwise and stirred for an
additional 2 h. The reaction was diluted
with ethyl acetate (20 ml) and washed with
2
.22 (t, J ¼ 6.6 Hz, 2H, CH ), 2.11
2
1
3
(
(
t, J ¼ 6.6 Hz, 2H, CH );
C NMR
150 MHz, CDCl ) d (ppm) 201.3, 172.6,
2
3
1
1
6
44.9, 136.4, 131.9, 130.1, 129.6, 129.4,
28.9, 127.8, 127.3, 126.6, 68.4, 68.3,
6.6, 45.6, 36.7, 32.1, 31.4, 31.3.
0
.1 N HCl solution (50 ml £2) and brine
30 ml). The organic layer was then dried
over Na SO , filtered, and the solvent was
(
3
.13 Ester (4)
2
4
7
(
(550 mg, 0.9 mmol), Fmoc-Val-OH
468 mg, 1.38 mmol), EDCI (265 mg,
removed by rotary evaporation. The
resulting crude was purified by flash
chromatography on silica gel, eluting
with dichloromethane–methanol mixture
(50:1 v/v) to afford 2 (220 mg, 75%) as a
1
0
.38 mmol), and DMAP (11 mg,
.09 mmol) were dissolved in dry CH Cl2
2
(20 ml). The reaction was cooled to 08C,
and iPr NEt was added dropwise. The
2
0
white solid. Mp 108–1108C; [a] 2 29 (c
2
D
1
0.1, CHCl ); H NMR (600 MHz, CDCl )
reaction mixture was allowed to warm to
room temperature and stirred for 30 min.
This solution was washed with 1N HCl
solution and water successively, dried over
Na SO , and filtered. After the removal of
3
3
d (ppm) 7.80 (s, 1H, CvCHS), 7.76 (d,
J ¼ 7.8 Hz, 2H, ArH), 7.55 (d, J ¼ 7.2 Hz,
2H, ArH), 7.19–7.40 (m, 19H, ArH), 6.86
(brs, 1H, NH), 5.67 (m, 1H, CHv), 5.62
(m, 1H, CH), 5.53 (m, 1H, CHv), 5.26
2
4
the solvent, the resulting crude was