PAPER
Nucleophilic Substitution on Furan and Thiophene
2711
1H NMR (500 MHz, CDCl3): δ = 7.34 (s, 1 H), 6.29 (d, J = 3.0 Hz,
1 H), 6.01 (d, J = 3.0 Hz, 1 H), 5.51 (s, 1 H), 4.07–4.13 (m, 4 H),
3.32 (s, 8 H), 1.10–1.13 (m, 6 H).
Methyl 2-({5-[1-(1,3-Dithiolan-2-ylidene)-2-oxo-2-phenyl-
ethyl]furan-2-yl}methyl)acrylate (6c)
Yield: 0.27 g (71%); white solid; mp 118–120 °C.
IR (KBr): 2928, 1704, 1632, 1506, 1294 cm–1.
HRMS (ESI): m/z [M + H]+ calcd for C19H23O5S4: 459.0423; found:
1H NMR (500 MHz, CDCl3): δ = 7.62 (d, J = 7.0 Hz, 2 H), 7.53 (s,
1 H), 7.42 (d, J = 7.0 Hz, 1 H), 7.37 (t, J = 7.0 Hz, 2 H), 7.33 (s, 1
H), 6.60 (d, J = 2.0 Hz, 1 H), 6.47 (d, J = 1.5 Hz, 1 H), 4.15 (s, 2 H),
3.64 (s, 3 H), 3.29 (t, J = 5.0 Hz, 2 H), 3.24 (t, J = 5.0 Hz, 2 H).
13C NMR (125 MHz, CDCl3): δ = 194.6, 168.5, 158.2, 151.5, 144.5,
139.4, 131.3, 128.7, 128.3, 126.7, 125.5, 123.4, 116.6, 112.3, 52.1,
38.5, 37.3, 33.2.
459.0418.
2,4-Di(1,3-dithiolan-2-ylidene)-3-(furan-2-yl)pentanedinitrile
(4e1)
Yield: 0.63 g (86%); white solid; mp 196–198 °C.
IR (KBr): 2248, 1738, 1568, 1398 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.44 (s, 1 H), 6.40 (d, J = 3.0 Hz,
1 H), 6.37 (d, J = 3.0 Hz, 1 H), 4.67 (s, 1 H), 3.54–3.62 (m, 8 H).
HRMS (ESI): m/z [M + H]+ calcd for C20H19O4S2: 387.0719; found:
387.0712.
13C NMR (125 MHz, CDCl3): δ = 165.2, 149.3, 143.1 (2 C), 117.0,
110.7 (2 C), 108.6 (2 C), 94.5, 47.4, 40.1 (4 C), 38.4 (4 C).
Methyl 2-({5-[1-(1,3-Dithiolan-2-ylidene)-2-ethoxy-2-oxoeth-
yl]furan-2-yl}methyl)acrylate (6d)
Yield: 0.26 g (73%); white solid; mp 74–76 °C.
HRMS (ESI): m/z [M + H]+ calcd for C15H13N2OS4: 364.9905;
found: 364.9900.
2,4-Di(1,3-dithiolan-2-ylidene)-3-(thiophen-2-yl)pentanedini-
trile (4e2)
IR (KBr): 2926, 1633, 1467, 1290 cm–1.
1H NMR (500 MHz, CDCl3): δ = 1.04 (t, J = 7.0 Hz, 3 H), 3.32 (t,
J = 5.0 Hz, 2 H), 3.38 (t, J = 5.0 Hz, 2 H), 3.72 (s, 3 H), 4.03 (s, 2
H), 4.07 (q, J = 7.0 Hz, 2 H), 6.47 (d, J = 2.0 Hz, 1 H), 6.63 (d, J =
2.5 Hz, 1 H), 7.39 (s, 1 H), 7.51 (s, 1 H).
13C NMR (125 MHz, CDCl3): δ = 168.4, 166.6, 159.8, 151.5, 144.0,
126.4, 126.3, 115.8, 114.4, 111.9, 60.4, 51.9, 38.8, 36.8, 31.9, 13.8.
Yield: 0.63 g (83%); white solid; mp 224–226 °C.
IR (KBr): 2257, 1836, 1685, 1397 cm–1.
1H NMR (500 MHz, DMSO-d6): δ = 7.52 (d, J = 4.0 Hz, 1 H), 7.05
(d, J = 4.0 Hz, 1 H), 7.03 (d, J = 4.0 Hz, 1 H), 4.81 (s, 1 H), 3.68–
3.71 (m, 8 H).
13C NMR (125 MHz, DMSO-d6): δ = 167.52, 140.59, 127.94 (2 C),
126.87, 126.74 (2 C), 117.7 (2 C), 95.2, 48.5, 40.8 (4 C), 39.2 (4 C).
HRMS (ESI): m/z [M + H]+ calcd for C15H13N2S5: 380.9677; found:
380.9671.
HRMS (ESI): m/z [M + H]+ calcd for C16H19O5S2: 355.0668; found:
355.0662.
Methyl (E)-2-({5-[1-(1,3-Dithiolan-2-ylidene)-2-oxo-4-phenyl-
but-3-enyl]furan-2-yl}methyl)acrylate (6e)
Yield: 0.28 g (69%); yellow solid; mp 82–84 °C.
IR (KBr): 2926, 1633, 1467, 1290 cm–1.
Methyl 2-({5-[1-(1,3-Dithiolan-2-ylidene)-2-oxopropyl]furan-2-
yl}methyl)acrylate (6a); Typical Procedure
To a solution of α-acetyl ketene S,S-acetal 1a (1.0 mmol, 160 mg)
in MeCN (8.0 mL) was added BF3·OEt2 (0.1 mmol, 0.012 mL) in
one portion. The reaction mixture was stirred vigorously. A solution
of the BH adduct 5a (1.0 mmol, 182 mg) in MeCN (3.0 mL) was
added dropwise to the above mixture while keeping at r.t. for 30
min. After the completion of the reaction as indicated by TLC, the
reaction mixture was quenched with H2O (20 mL) and extracted
with Et2O (3 × 15 mL). The combined organic extracts were washed
with brine (3 × 20 mL), dried (Na2SO4), filtered, and concentrated.
Purification was carried out by flash silica gel chromatography us-
ing PE–Et2O (3:1, v/v) as eluent to give product 6a; yield: 0.25 g
(77%); white solid; mp 94–96 °C.
1H NMR (500 MHz, CDCl3): δ = 7.63 (d, J = 14.5 Hz, 2 H), 7.45 (s,
1 H), 7.25–7.30 (m, 6 H), 6.73 (d, J = 3.0 Hz, 1 H), 6.59 (s, 1 H),
4.33 (s, 2 H), 3.68 (s, 3 H), 3.38 (t, J = 6.0 Hz, 2 H), 3.36 (t, J = 6.5
Hz, 2 H).
13C NMR (125 MHz, CDCl3): δ = 186.3, 168.4, 151.4, 144.9, 142.5,
135.8, 129.9, 128.9, 128.3, 126.6, 126.5, 123.6, 123.2, 117.2, 112.5,
110.0, 52.2, 39.3, 36.4, 32.4.
HRMS (ESI): m/z [M + H]+ calcd for C22H21O4S2: 413.0876; found:
413.0871.
Ethyl 2-({5-[1-(1,3-Dithiolan-2-ylidene)-2-oxopropyl]furan-2-
yl}methyl)acrylate (6f)
Yield: 0.24 g (72%); white solid; mp 130–132 °C.
IR (KBr): 2926, 1700, 1629, 1476, 1255 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.59 (s, 1 H), 7.46 (s, 1 H), 6.70
(d, J = 3.0 Hz, 1 H), 6.54 (d, J = 2.5 Hz, 1 H), 4.19 (q, J = 7.5 Hz, 2
H), 4.17 (s, 2 H), 3.24–3.31 (m, 4 H), 2.38 (s, 3 H), 1.27 (t, J = 7.0
Hz, 3 H).
13C NMR (125 MHz, CDCl3): δ = 195.3, 168.0, 160.9, 151.5, 144.6,
126.8, 126.3, 123.0, 116.7, 112.3, 61.2, 38.9, 36.4, 32.3, 28.0, 14.4.
IR (KBr): 2926, 1633, 1467, 1290 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.60 (s, 1 H), 7.47 (s, 1 H), 6.71
(d, J = 3.0 Hz, 1 H), 6.55 (d, J = 3.0 Hz, 1 H), 4.18 (s, 2 H), 3.75 (s,
3 H), 3.32 (t, J = 6.0 Hz, 2 H), 3.26 (t, J = 6.5 Hz, 2 H), 2.41 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 195.1, 168.1, 160.8, 151.2, 144.4,
126.7, 125.7, 122.6, 116.5, 112.0, 51.9, 38.6, 36.1, 32.1, 27.5.
HRMS (ESI): m/z [M + H]+ calcd for C15H17O4S2: 325.0563; found:
325.0559.
HRMS (ESI): m/z [M + H]+ calcd for C16H19O4S2: 339.0719; found:
339.0712.
Methyl 2-({5-[1-(1,3-Dithian-2-ylidene)-2-oxopropyl]furan-2-
yl}methyl)acrylate (6b)
Yield: 0.22 g (64%); white solid; mp 86–88 °C.
IR (KBr): 2949, 1706, 1628, 1457, 1254 cm–1.
2-({5-[1-(1,3-Dithiolan-2-ylidene)-2-oxopropyl]furan-2-
yl}methyl)acrylonitrile (6g)
1H NMR (500 MHz, CDCl3): δ = 7.57 (d, J = 5.5 Hz, 1 H), 7.44 (d,
J = 5.0 Hz, 1 H), 6.68 (d, J = 3.5 Hz, 1 H), 6.53 (d, J = 3.5 Hz, 1 H),
3.76 (s, 3 H), 4.14 (s, 2 H), 2.95 (t, J = 7.0 Hz, 2 H), 2.88 (t, J = 7.0
Hz, 2 H), 2.32 (s, 3 H), 2.14–2.18 (m, 2 H).
13C NMR (125 MHz, CDCl3): δ = 197.4, 168.4, 151.4, 144.6, 133.1,
126.7, 126.3, 116.6, 112.3, 52.2, 30.7, 29.6, 29.4, 29.3, 24.1.
Yield: 0.19 g (67%); white solid; mp 86–88 °C.
IR (KBr): 2927, 2220, 1625, 1468, 1275 cm–1.
1H NMR (500 MHz, CDCl3): δ = 7.52 (s, 1 H), 6.93 (d, J = 2.5 Hz,
1 H), 6.65 (s, 1 H), 6.49 (d, J = 2.0 Hz, 1 H), 3.68 (s, 2 H), 3.44 (t,
J = 6.5 Hz, 2 H), 3.36 (t, J = 6.5 Hz, 2 H), 2.29 (s, 3 H).
13C NMR (125 MHz, CDCl3): δ = 193.7, 166.7, 149.7, 144.6, 130.3,
118.9, 118.4, 114.5, 112.6, 103.9, 39.8, 38.9, 36.2, 27.5.
HRMS (ESI): m/z [M + H]+ calcd for C16H19O4S2: 339.0719; found:
339.0711.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 2707–2712