868
L. C. de Souza et al. / Bioorg. Med. Chem. 12 (2004) 865–869
or ethyl acetoacetate (7.85 mmol), to synthesis of com-
pounds 6–9, was added dropwise. The mixture was stir-
red for 15 min, and then n-BuLi (1.2 mol/L in hexane,
5H); 13C NMR (125 MHz, DMSO d ) d 34.1; 76.1; 90.8;
6
1
13
126.3; 128.2; 128.4; 139.1; 166.7; 172.7. H and
NMR relative to enol form of (7).
C
1
0 mL, 11.78 mmol) was added dropwise. The solution
was stirred for another 15 min, and then an aldehyde
8.64 mmol) was added dropwise. After 30 min, the
4.3.4. 6-(4-methoxy-phenyl)-dihydro-pyran-2,4-dione (8).
Compound 8 (0.731g, 3.32 mmol, 42%) was obtained
from ethyl acetoacetate (1.00 mL, 7.85 mmol) and p-
(
reaction mixture was poured into NaOH (0.5 mol/L,
ꢀ
ꢀ
5
00 mL). After 2 h at 25 C, the reaction mixture was
partitioned between Et O and water, and the aqueous
anisaldehyde (1.05 mL, 8.64 mmol); mp: 181–183 C
(from chloroform); IR(KBr) n
2545; 1881; 1712.5; 1608; 1427; 1390; 1345; 1172; 1012;
3059; 2949; 2839;
´
max
2
phase was extracted with two additional portions of
Et O. The aqueous phase was cooled with ice and acid-
À1
1
945; 911; 842; 771 and 662 cm ; H NMR (300 MHz,
DMSO d ) d 2.56 (dd, 1H, J=3.0 and 17.0 Hz); 2.89
2
ified until pH 6 with concentrated HCl. The resulting
precipitate was extracted with AcOEt (3Â50 mL). The
combined extracts were washed with water (2Â100 mL)
and brine (2Â50 mL), dried under Na SO , and con-
6
(dd, 1H, J=12.0 and 17.0 Hz); 3.80 (s, 3H); 3.86 (s, 1H);
5.12 (s, 1H); 5.42 (dd, 1H, J=3.0 and 12.0); 6.98–7.07
1
3
(m, 2H); 7.42–7.45 (m, 2H); C NMR (75 MHz, DMSO
d6) d 55.2; 76.1; 90.9; 113.8; 127.9; 131.0; 131.4; 159.3;
166.9; 172.8.
2
4
centrated under reduced pressure. Recrystalization of
these compounds using CHCl provided the dihydro-
3
pyran-2,4-diones.
4.3.5. 6-(3,4-dimethoxy-phenyl)-dihydro-pyran-2,4-dione
(
9). Compound 9 (1.355 g, 5.41 mmol, 69%) was
obtained from ethyl acetoacetate (1.00 mL, 7.85 mmol)
4
4
.3. Structural data for dihydro-pyran-2,4-diones (5–9)
.3.1. 5,6-dimethyl-dihydro-pyran-2,4-dione (5). Com-
and 3,4-dimethoxy-benzaldehyde (1.434g, 8.64 mmol);
ꢀ
pound 5 (0.496 g, 3.49 mmol, 48%) was obtained from
ethyl 3-oxo-pentanoate (1.00 mL, 7.27 mmol) and acet-
aldehyde (0.43 mL, 8.64 mmol); mp: 112–114 C (cis),
mp: 150–153 C (from chloroform); IR (KBr) n
3006, 2944, 2842, 1852, 1727, 1594, 1518, 1443, 1383,
3080,
max
´
ꢀ
1340, 1270, 1154, 1054, 1030, 1004, 925, 893, 846, 773,
À1
ꢀ
980, 2668, 1649, 1572, 1383, 1284, 1227, 1087, 819 e
07 cm ; trans- n
587, 2550, 1626, 1598, 1501, 1452, 1384, 1326, 1298,
1
8
2
6
2
1
5–87 C (trans) (from chloroform); IR: (KBr): cis- n
754, 660 and 639 cm ; H NMR (500 MHz, DMSO d )
6
ma
´
x
d? 2.88–2.93 (m, 1H), 3.76 (s, 3H); 3.78 (s, 3H), 5.35–
5.37 (m, 1H), 6.96 (d, 1H, J=8.3 Hz), 6.98 (dd, 1H,
J=1.5 Hz and 8.3 Hz), 7.07 (d, 1H, J=1.5 Hz);
À1
2997, 2984, 2942, 2886, 2688,
max
´
1
3
C
À1
1
233, 1049, 1005 and 826 cm ; H NMR (400 MHz,
NMR (125 MHz, DMSO d ) d 55.5; 76.3; 90.8; 110.4;
6
CDCl ): cis- d 1.15 (d, 3H, J=7.3 Hz), 1.39 (d, 3H,
111.5; 118.9; 131.4; 148.8; 166.9; 172.9.
3
J=6.7 Hz), 2.68, 2.74 (m, 1H), 3.40 (d, 1H, J=19.9 Hz),
3
1
2
.54 (d, 1H, J=19.9 Hz) and 4.80–4.86 (m, 1H); trans- d
.19 (d, 3H, J=7.3 Hz), 1.53(d, 3H, J=6.7 Hz), 2.30–
.38 (m, 1H), 3.44 (d, 1H, J=19.1 Hz), 3.56 (d, 1H,
4
.4. Founder Snail
Snails (shell diameter 19–25 mm) were isolated from a
laboratory stock, originally derived from a, not infected
by trematodes colony originated from Barreiro de
Cima, a district of Belo Horizonte, Minas Gerais and
reared in the laboratory for at least six years previously.
1
3
J=19.1 Hz) and 4.41–4.48 (m, 1H);
(
C NMR
100 MHz, CDCl ): cis- d 9.1; 16.6; 45.5; 46.6; 74.9;
3
1
67.3; 203.0; trans- d 10.6; 19.0; 45.8; 48.5; 76.9; 167.0;
2
02.4.
ꢀ
The snails were maintained at 25–27 C in a glass of
4.3.2. 6-propenyl-dihydro-pyran-2,4-dione (6). Com-
pound 6 (0.968 g, 6.28 mmol, 80%) was obtained from
aquarium (22Â30Â44 cm) containing dechlorinated
current water system and were fed ad libitum with fresh
lettuce and the medium was replenished every day.
These snails provided egg capsules for subsequent
experiments.
ethyl acetoacetate (1.00 mL, 7.85 mmol) and croton-
ꢀ
aldehyde (0.72 mL, 8.64 mmol); mp: 122–124 C (from
3080, 2963, 2640, 1886,
max
´
chloroform); IR (KBr) n
1
1
841, 1690, 1587, 1449, 1418, 1370, 1357, 1276, 1256,
186, 1100, 1057, 1012, 965, 937, 894, 875, 745 and 567
4.5. Molluscicidal activity for bioassay
À1
1
cm ; H NMR (500 MHz, DMSO d ) d 1.70 (d, 3H,
6
J=6,5 Hz), 2.38–2.24 (m, 2H), 2.48–2.54 (m, 2H), 4.96
B. glabrata egg masses were obtained from a colourless
polyethylene sheet previously placed in the aquarium. In
the test for evaluation of the ovicidal activity was used
one egg mass aged 0–2 day-old for concentration. Egg
masses were exposed to potential molluscicide for 24 h
at room temperature and were kept under normal diur-
nal lighting. After 24 h, the suspension was decanted,
the egg mass rinsed twice with aerated tap water. The
test egg masses were then left in water for another 72 h
(time of recovery). Of each 24 h the target organism
were examined to assess mortality. The mass of each
individual embryo was checked with a binocular micro-
scopic. Egg mass were considered dead when their cells
became opaque, dull or disaggregated. Three control
sets were used in order to verify the snail susceptibility,
(
(
s, 1H), 5.60 (dd, 1H, J=6.5 and 15.4 Hz), 5.77–5.84
1
3
m, 1H); C NMR (125 MHz, DMSO d ) d 17.4; 32.7;
6
7
5.09; 90.8; 128.9; 129.0; 166.7; 172.3.
4
.3.3. 6-phenyl-dihydro-pyran-2,4-dione (7). Compound
7
acetoacetate (1.00 mL, 7.85 mmol) and benzaldehyde
(0.910 g–4.78 mmol, 61%) was obtained from ethyl
ꢀ
(
1.32 mL, 8.64 mmol); mp: 129–131 C (from chloro-
3036, 2898,
max
´
ꢀ
554, 1719, 1592, 1498, 1460, 1399, 1372, 1289, 1207,
form) (lit. Mp 132–134 C); IR (KBr) n
2
1
À1
1
186, 1162, 1059, 1012, 817, 756 and 696 cm ; H
NMR (500 MHz, DMSO d ) d 2.59 (dd, 1H, J=3.5 and
6
1
1
7.0 Hz), 2.85 (dd, 1H, J=11.9 and 17.0 Hz), 5.07 (s,
H), 5.45 (dd, 1H, J=3.5 and 11.9 Hz), 7.35–7.48 (m,