7
76
Kvíčala et al.:
3
-Fluoro-4-[phenylbis(phenylsulfanyl)methyl]-4,5-dihydrofuran-2(3H)-one (3a). Reaction of
–
1
dith ioacetal 7a (685 m g, 2.22 m m ol), BuLi solution (1.40 m l, 1.89 m ol l , 2.50 m m ol), an d
fluorolacton e 1 (202 m g, 1.98 m m ol) in THF (6 m l) afforded after purification by colum n
ch rom atograph y (SiO , 20 × 3 cm , gradien t elution first with petroleum eth er–CH Cl 4 : 1,
2
2
2
th en with CH Cl ) fluorolacton e 3a (wh ite crystals, 352 m g, 41.4%, m .p. 46–52 °C) as a
2
2
1
m ixture of diastereoisom ers ((3R*,4R*)/(3R*,4S*) = 57 : 43). H NMR (300.1 MHz, CDCl ):
3R*,4R*)-3a 3.50 ddt, 1 H, JH,H = 8.2, JH,H = 6.6 (t),
3
3
3
3
(
J
= 25.8 (CH-CHF); 4.41 dd, 1 H,
= JH,H = 9.3 (OCH H -CH); 5.31 dd,
H,F
2
3
2
3
JH,H = 9.9, JH,H = 7.1 (OCH H -CH); 4.58 t, 1 H, JH,H
a
b
a
b
H, 3J
= 6.1, 2J
= 49.5 (CHF); 7.23–7.35 m , 13 H (Ar-H); 7.68 d, 2 H, JH,H = 8.2 (Ar-H);
H,F
3
1
H,H
3
3
3
(
2
3R*,4S*)-3a 3.20 ddt, 1 H, JH,H = 7.1 (t), JH,H = 6.6, JH,F = 20.3 (CH-CHF); 4.54 dd, 1 H,
3
= 7.1 (OCH H -CH); 4.90 dd, 1 H, 2J
3
JH,H = 9.9,
J
3
= 9.9, JH,H = 6.6 (OCH H -CH);
H,H a b
H,H
a
b
2
13
5
.17 dd, 1 H, JH,H = 7.2, JH,F = 50.6 (CHF); 7.10–7.80 m , 15 H (Ar-H). C NMR (100.6 MHz,
CDCl ): (3R*,4R*)-3a 50.3 d, JC,F = 19 (CH-CHF); 67.8 d,
C(SPh ) ); 88.4 d,
3R*,4S*)-3a 48.3 d, JC,F = 17 (CH-CHF); 68.5 s (OCH -CH); 69.8 s (C(SPh ) ); 86.7 d, JC,F
99 (CHF); 128.8–136.8 all s, 18 C (CAr); 171.3 d, JC,F = 16 (CO). F NMR (76.5 MHz,
CDCl ): (3R*,4R*)-3a –187.1 dd, 1 F, JH,F = 50, JH,F = 26 (CHF); (3R*,4S*)-3a –202.4 dd, 1 F,
JH,F = 51, JH,F = 21 (CHF). IR (CHCl ): 1 026 m , 1 219 s, 1 440 m , 1 478 w, 1 799 s, 3 025
3
4
J
= 5 (OCH -CH); 69.3 s
3
C,F 2
1
= 190 (CHF); 128.8–136.8 all s, 18 C (CAr); 171.1 d, 2JC,F = 16 (CO);
(
(
1
J
2
C,F
3
1
=
2
2
2
19
2
3
3
2
3
3
w. For C23H19FO2S2 (410.5) calculated: 67.3% C, 4.6% H; foun d: 65.5% C, 4.78% H.
-Fluoro-4-[(4-methoxyphenyl)bis(phenylsulfanyl)methyl]-4,5-dihydrofuran-2(3H)-one (3b). Re-
3
–
1
action of dith ioacetal 7b (708 m g, 2.09 m m ol), BuLi solution (1.32 m l, 1.89 m ol l , 2.25
m m ol), an d fluorolacton e 1 (205 m g, 2.01 m m ol) in THF (6 m l) afforded after purification
by repeated colum n ch rom atograph y (first SiO , 30 × 3 cm , eluen t petroleum eth er–CH Cl
2
2
2
1
: 1, th en SiO , 15 × 3 cm , eluen t CH Cl ) fluorolacton e 3b (wh ite crystals, 462 m g, 52.4%)
2 2 2
1
as a m ixture of diastereoisom ers ((3R*,4R*)/(3R*,4S*) 44 : 56). H NMR (300.1 MHz, CDCl ):
3
3
3
3
(
3R*,4R*)-3b 3.44 ddt, 1 H, JH,H = 8.2, JH,H = 6.6 (t), JH,F = 25.8 (CH-CHF); 3.82 s, 3 H
2
3
2
3
(
CH O); 4.29 dd, 1 H, JH,H = 10.0, JH,H = 7.2 (OCH H -CH); 4.55 dd, 1 H, JH,H = 9.9, JH,H
3 a b
3
2
3
=
(
8.8 (OCH H -CH); 5.27 dd, 1 H, JH,H = 6.1, JH,F = 50.0 (CHF); 6.85 d, 2 H, JH,H = 8.8
a b
Ar-H); 7.23–7.35 m , 10 H (Ar-H); 7.60 d, 2 H, 3J
= 8.2 (Ar-H); (3R*,4S*)-3b 3.11 dq, 1 H,
H,H
3
3
2
3
JH,H = 7.1 (q), JH,F = 22.9 (CH-CHF); 3.81 s, 3 H (CH O); 4.53 dd, 1 H, JH,H = 9.3, JH,H
=
=
3
2
3
3
7
.1 (OCH H -CH); 4.85 dd, 1 H,
J
= 9.3, JH,H = 6.6 (OCH H -CH); 5.14 dd, 1 H, JH,H
a
b
H,H a b
2
3
6
.6, JH,F = 50.6 (CHF); 6.83 d, 2 H, JH,H = 9.3 (Ar-H); 7.08–7.38 m , 10 H (Ar-H); 7.52 d, 2 H,
3
JH,H = 8.9 (Ar-H). 13C NMR (100.6 MHz, CDCl ): (3R*,4R*)-3b 50.3 d, JC,F = 19 (CH-CHF);
2
3
3
1
5
5.9 s (OCH ); 67.8 d, JC,F = 8 (OCH -CH); 67.6 s (C(SPh ) ); 88.2 d, JC,F = 190 (CHF); 114.5
3 2 2
2
s, 2 C (CAr); 129.4–135.9 all s, 15 C (CAr); 160.2 s (CAr-OCH ); 171.3 d, JC,F = 22 (CO);
3
(
3R*,4S*)-3b – th is diastereoisom er was n ot sufficien tly separated from th e form er on e to en -
1
9
2
able un equivocal assign m en t. F NMR (76.5 MHz, CDCl ): (3R*,4R*)-3b –187.5 dd, 1 F, JH,F
=
1
3
50, JH,F = 26 (CHF); (3R*,4S*)-3b –202.9 dd, 1 F, 2JH,F = 51, JH,F = 22 (CHF). IR (CHCl ):
3
3
3
027 m , 1 091 w, 1 257 s, 1 440 w, 1 509 m , 1 793 s, 3 012 w. Microan alysis was n ot ac-
com plish ed due to low stability of th e product.
-[(3,4-Dimethoxyphenyl)bis(phenylsulfanyl)methyl]-3-fluoro-4,5-dihydrofuran-2(3H)-one (3c).
4
–
1
Reaction of dith ioacetal 7c (733 m g, 1.99 m m ol), BuLi solution (0.90 m l, 2.19 m ol l , 1.99
m m ol), an d fluorolacton e 1 (204 m g, 2.00 m m ol) in THF (6 m l) afforded after purification
by repeated colum n ch rom atograph y (first SiO , 30 × 3 cm , eluen t petroleum eth er–CH Cl
2
2
2
1
: 1, th en SiO , 15 × 3 cm , eluen t CH Cl ) fluorolacton e 3c (wh ite crystals, 538 m g, 57.2%,
2 2 2
1
m .p. 48–51 °C) as a m ixture of diastereoisom ers ((3R*,4R*)/(3R*,4S*) 63 : 37). H NMR (300.1
MHz, CDCl ): (3R*,4R*)-3c 3.44 ddt, 1 H, JH,H = 8.8, JH,H = 6.6 (t), JH,F = 25.8 (CH-CHF);
3
3
3
3
Collect. Czech. Chem. Commun. (Vol. 65) (2000)