With the rapid development and complex challenges of chemical substances, new drug synthesis pathways are usually the most effective.108-55-4,Dihydro-2H-pyran-2,6(3H)-dione,as a common compound, the synthetic route is as follows.
A flask was charged with AlCl3 (77.17 mmol, 10.29 g, 2.15 equiv) and dry CH2Cl2 (25 ml) under calcium chloride guard tube and the formed suspension was stirred on ice bath. Subsequently, a solution of glutaric anhydride 10 (35.8 mmol, 4.08 g) in dry CH2Cl2 (12 ml) was added dropwise (t < 8 C). The resulting mixture was stirred on ice bath for 30 minutes and fluorobenzene 11c (35.1 mmol, 3.37 g, 1.0 equiv) was carefully added afterwards. The cooling bath was removed and the mixture was stirred at room temperature for 19 hours, then it was carefully quenched with ice water (20 ml), conc. H2SO4 (10 ml) and again with ice water (60 ml), the aqueous layer was extracted with ethyl acetate (1 x 200 ml, 1 x 100 ml, 1 x 70 ml), the combined organics were washed with half-saturated brine (200 ml), dried over Na2SO4, filtered and concentrated. The crude product was crystallized from ethyl acetate to provide 5-(4-fluorophenyl)-5-oxopentanoic acid (3.80 g, 51%) as a yellow-brown powder;3 mp 141-142 C; 1H NMR (300 MHz, CDCl3): delta = 2.08 (m, 2H), 2.51 (t, J = 7.2 Hz, 2H), 3.05 (t, J = 7.2 Hz, 2H), 7.13 (m, 2H), 7.99 (m, 2H). 5-(4-Fluorophenyl)-5-oxopentanoic acid (16.7 mmol, 3.50 g), paraformaldehyde (50.0 mmol, 1.50 g, 3.0 equiv) and piperidine (0.32 ml, 0.2 equiv) were dissolved/suspended in pyridine (15 ml) and stirred at 70 C for 21 hours. Afterwards, the mixture was poured into 1M H2SO4 (340 ml), the aqueous layer was extracted with ethyl acetate (4 x 100 ml), the combined organics were dried over Na2SO4, filtered and concentrated. The residue was purified by flash chromatography on silica gel (EA/hexanes = 1/1 + 0.5% AcOH). The obtained product was repeatedly coevaporated with toluene (4 x 25 ml) under reduced pressure to remove the residual AcOH, yielding 4-(4-fluorobenzoyl)pent-4-enoic acid 9c (3.33 g, 90%) as an orange solid; mp 81-82 C; 1H NMR (300 MHz, CDCl3): delta = 2.62 (t, J = 7.2 Hz, 2H), 2.80 (t, J = 7.2 Hz, 2H), 5.65 (s, 1H), 5.92 (s, 1H), 7.12 (dd, J = 8.7, 8.7 Hz, 2H), 7.78 (dd, J = 5.7, 8.7 Hz, 2H), 10.74 (bs, 1H); 13C NMR (75 MHz, CDCl3): delta = 27.3, 32.5, 115.3 (d, JCF = 21.8 Hz), 126.7, 132.0 (d, JCF = 9.0 Hz), 133.7, 145.9, 165.3 (d, JCF = 252.5 Hz), 178.9, 196.2, 108-55-4
The synthetic route of 108-55-4 has been constantly updated, and we look forward to future research findings.
Reference£º
Article; Sivak, Ivan; Berke?, Du?an; Ko?i?ek, Jozef; Kolarovi?, Andrej; Tetrahedron Letters; vol. 57; 10; (2016); p. 1079 – 1082;,
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