An Innovative and Concise Approach to Synthesize Pyriftalid
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1-Methyl-3-oxo-1,3-dihydroiso-benzofuran-4-yl ethanethioate (8)
Compound 3 (5.00 g, 25.9 mmoL) was added to 20 mL DMF, then potassium thioacetate 6
(3.55 g, 31.0 mmoL) was added. The reaction mixture was stirred at at 25–35ꢀC for 5h.The
reaction mixture was poured into ice/water (20 g) and extracted with CH2Cl2 (25 mL). The
organic layer was separated, washed with water (20 mL £ 3), dried with Na2SO4, and fil-
tered. The solvent was evaporated under vacuum to give a yellow solid (6.05 g). The crude
product was purified by column chromatography (Al2O3, PE:EtOAc D 3:1, v/v) to give
pure 8 as a white solid (2.58 g, 45%). Mp 86.7–88.6ꢀC; IR (KBr): 3073 (aromatic C-Hn),
2985, 2925,2843 (C-Hn), 1756 (O-C D On), 1699 (S-C D On), 1593, 1507 (aromatic
1
C D Cn), 1472, 1375 (C-Hd), 1246, 1115 (C-O-Cn), 702 (aromatic C-Hd) cm¡1; H NMR
(400 MHz, CDCl3) d 7.66 (d, J D 7.6 Hz, 1H), 7.61 (d, J D 7.5 Hz, 1H), 7.45 (d,
J D 7.5 Hz, 1H), 5.51 (q, J D 6.7 Hz, 1H), 2.50 (s, 3H), 1.63 (d, J D 6.7 Hz, 3H); 13C
NMR (100 MHz, CDCl3) d 191.95, 168.11, 153.00, 135.93, 134.14, 128.62, 126.34,
122.87, 76.40, 30.85, 20.32; HRMS (ESI) m/z 222.0347 (calcd for C11H10O3S, 222.0351).
Anal. Calcd for C11H10O3S: C, 59.44; H, 4.53. Found: C, 59.64; H, 4.65.
7,70-Thiobis(3-methylisobenzofuran-1(3H)-one) (15)
Compound 5 (1.00 g, 5.6 mmoL) was added to 10 mL DMF, then 1.14 g Compound 3
(5.9 mmoL), triethylamine (0.63 g, 6.2 mmoL) was added. The reaction mixture was
heated to 80ꢀC for 2h under a nitrogen atmosphere. The reaction was monitored by TLC
(silaca gel PE:EtOAc D 3:1, v/v). Then the reaction mixture was poured into water
(20 mL) and extracted with CH2Cl2 (20 mL). The organic layer was separated, washed
with water (20 mL £ 3), dried with Na2SO4, and filtered. The solvent was evaporated in
vacuum to give a brown oil. Recrystallization from methanol (3 mL) give pure 15 as a
yellow solid (0.76 g, 84%). Mp 212.6–215.5ꢀC; IR (KBr): 3069 (aromatic C-Hn), 2923,
2853 (C-Hn), 1738 (C D On), 1586 (aromatic C D Cn), 1456, 1375 (C-Hd), 1211, 1045
(C-O-Cn), 702 (aromatic C-Hd) cm¡1; 1H NMR (400 MHz, CDCl3) d 7.91 (d, J D 7.7 Hz,
1H), 7.85 (t, J D 7.7 Hz, 1H), 7.70 (d, J D 7.5 Hz, 1H), 5.60 (q, J D 6.7 Hz, 1H), 1.69
(d, J D 6.7 Hz, 3H); 13C NMR (100 MHz, CDCl3) d 168.33, 153.01, 135.14, 134.49,
131.32, 124.40, 120.45, 76.82, 20.43; HRMS (ESI) m/z 326.0608 (calcd for C18H14O4S,
326.0613).
Anal. Calcd for C18H14O4S: C, 66.24; H, 4.32. Found: C, 66.10; H, 4.36.
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