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HETEROCYCLES, Vol. 65, No. 7, 2005
J = 7 Hz, 4H), 1.67 (br s, 6H). IR (nujol): 3392, 2924, 2850, 1510 cm-1. Anal. Calcd for C21H23N5O3Cl2S: C,
50.81; H, 4.67; N, 14.11. Found: C, 51.05; H, 4.86; N, 14.37.
2-(3-Piperidinopyrazol-4-yl)-5-[2-(N,N-dimethylamino)thiazol-5-yl]-3,6-dichlorohydroquinone (4e):
A mixture of benzofuran (2a) (1.25 g, 3 mmol) and 4,4-pentamethylenthiosemicarbazide (0.47 g, 3 mmol)
in ethanol (20 mL) was stirred at rt for 2 h and then refluxed for 3 h with a drop of H2SO4. 0.2 g of activated
carbon was added and the hot solution was filtered off. After cooling, the precipitate was filtered and
washed with hexane. Yield 0.64 g (47%), mp >2500 C (decomp). 1H NMR (DMSO-d6): δ 9.27 (br s, 2H),
7.98 (s, 1H), 7.47 (s, 1H), 3.23 (s, 6H), 3.01 (br s, 4H), 1.54 (br s, 6H). IR (nujol): 3104, 2924, 2856, 1516
cm-1. Anal. Calcd for C19H21N5O2Cl2S: C, 50.23; H, 4.66; N, 15.41. Found: C, 50.45; H, 4.98; N, 15.48.
2-(3-Morpholynopyrazol-4-yl)-5-(2-piperidinothiazol-5-yl)-3,6-dichlorocyclohexa-2,5-diene-1,4-
dione (5d) and 2-(3-piperidinopyrazol-4-yl)-5-[2-(N,N-dimethylamino)thiazol-5-yl]-3,6-dichloro-
cyclohexa-2,5-diene-1,4-dione (5e): FeCl3 (20% in water, 30 mL, 37 mmol) was added to a solution of
hydroquinone (4d) or (4e) (2 mmol) in ethanol (30 mL). The reaction mixture was stirred for 1 h and then
was extracted twice with 20 mL methylene chloride, the organic layer was dried over magnesium sulfate.
The solvent was evaporated under reduced pressure and then the precipitate was recrystallized from ethanol.
5d: yield 0.53 g (54%), mp >2500 C (decomp). 1H NMR (DMSO-d6): δ 8.64 (s, 1H), 7.87 (s, 1H), 3.60 (br
s, 4H), 3.41 (t, J = 7 Hz, 4H), 3.03 (t, J = 7 Hz, 4H), 1.67 (br s, 6H). IR (nujol): 2928, 2860, 1656, 1612 cm-1.
UV-VIS: λmax (log ε, CHCl3): 344 (4.10); 640 (3.65) nm. Anal. Calcd for C21H21N5O3Cl2S: C, 51.02; H,
1
4.28; N, 14.17. Found: C, 51.24; H, 4.49; N, 14.37. 5e: yield 0.44 g (48%), mp >2500 C (decomp). H
NMR (DMSO-d6): δ 8.49 (s, 1H), 7.94 (s, 1H), 3.18 (s, 6H), 3.07 (br s, 4H), 1.54 (br s, 6H). IR (nujol): 2929,
2856, 1632 cm-1. Anal. Calcd for C19H19N5O2Cl2S: C, 50.45; H, 4.23; N, 15.48. Found: C, 50.63; H, 4.47; N,
15.61.
O-Butyl S-[6-(2-(N,N-dimethylamino)thiazol-5-yl)-4,7-dichloro-2,5-dihydroxy-2,3-dihydrobenzo[b]-
furan-3-yl]xanthate (6a)15 and O-Butyl S-[6-(2-piperidinothiazol-5-yl)-4,7-dichloro-2,5-dihydroxy-
2,3-dihydrobenzo[b]furan-3-yl]xanthate (6b)15: A solution of potassium O-butylxanthate (0.6 g, 3.2
mmol) in 20 mL of methanol was added dropwise to a stirred solution of the benzofuran (2a,b) (3 mmol) in
20 mL of methanol. The reaction mixture was stirred at rt for 3 h, poured into 150 mL of water. The product
was extracted with methylene chloride, then the organic layer was dried over magnesium sulfate and the
solvent was evaporated. The precipitate was recrystallized from carbon tetrachloride. 6a: Yield 1.03 g
(69%), mp 190-1920 C. 1H NMR (DMSO-d6): δ 9.43 (s, 1H), 8.18 (d, J = 6 Hz, 1H), 7.23 (s, 1H), 6.01 (dd,
J= 6 Hz, J < 0.5 Hz, 1H), 5.07 (d, J < 0.5 Hz, 1H), 4.65 (t, J = 6 Hz, 2H), 3.07 (s, 6H), 1.72 (quintet, J = 6
Hz, 2H), 1.29 (sextet, J = 6 Hz, 2H), 0.89 (t, J = 6 Hz, 3H). Anal. Calcd for C18H20N2O4Cl2S3 : C, 43.64; H,
1
4.07; N, 5.65. Found C, 43.86; H, 4.39; N, 5.48. 6b: Yield 0.98 g (61%), mp 185-1870C. H NMR
(DMSO-d6): δ 9.41 (s, 1H), 8.18 (d, J = 6.2 Hz, 1H), 7.23 (s, 1H), 5.96 (dd, J = 6.2 Hz, J < 0.5 Hz, 1H), 5.07