108-55-4, Dihydro-2H-pyran-2,6(3H)-dione is a Tetrahydropyrans compound, ?involved in a variety of chemical synthesis. Rlated chemical reaction is continuously updated
A flask was charged with AlCl3 (96.38 mmol, 12.85 g, 2.2 equiv) and dry benzene (20 ml) under calcium chloride guard tube and the formed suspension was stirred on ice bath. Subsequently, a solution of glutaric anhydride 10 (43.8 mmol, 5.00 g) in dry benzene (40 ml) was added dropwise over 30 minutes (t < 8 C). The cooling bath was removed and the resulting mixture was stirred at room temperature for 19 hours. The mixture was carefully quenched with water (95 ml) and conc. H2SO4 (10 ml), the aqueous layer was extracted with ethyl acetate (1 x 200 ml, 3 x 50 ml), the combined organics were dried over Na2SO4, filtered and concentrated. The crude product was crystallized from ethyl acetate to yield 5-oxo-5-phenylpentanoic acid (7.00 g, 83%) as a yellow-brown powder;1 mp 124-125 C; 1H NMR (300 MHz, acetone-d6): delta = 1.99 (m, 2H), 2.44 (t, J = 7.2 Hz, 2H), 3.13 (t, J = 7.2 Hz, 2H), 7.51 (m, 2H), 7.62 (m, 1H), 8.01 (d, J = 7.8 Hz, 2H), 10.56 (bs, 1H). 5-Oxo-5-phenylpentanoic acid (26.1 mmol, 5.02 g), paraformaldehyde (78.3 mmol, 2.35 g, 3.0 equiv) and piperidine (5.3 mmol, 0.52 ml, 0.2 equiv) were dissolved/suspended in pyridine (22 ml) and stirred at 70 C for 21 hours. Afterwards, the mixture was poured into 3M H2SO4 (100 ml), the aqueous layer was extracted with ethyl acetate (3 x 100 ml), the combined organics were dried over Na2SO4, filtered and concentrated. The residue was redissolved in CH2Cl2 (100 ml) and extracted with a mixture of half-saturated aqueous NaHCO3 (300 ml) and 2M NaOH (20 ml). The extraction was repeated with half-saturated aqueous NaHCO3 (50 ml). The combined aqueous solutions were washed with CH2Cl2 (2 x 50 ml) and afterwards acidified with conc. H2SO4 to pH = 1-2 and extracted with ethyl acetate (1 x 100 ml, 3 x 70 ml). The combined organics were dried over Na2SO4, filtered and concentrated to give 4-benzoylpent-4-enoic acid 9a (4.60 g, 86%) as a yellow solid; mp 45-46 C; 1H NMR (300 MHz, CDCl3): delta = 2.63 (t, J = 7.2 Hz, 2H), 2.81 (t, J = 7.2 Hz, 2H), 5.69 (s, 1H), 5.94 (s,1H), 7.43 (m, 2H), 7.54 (m, 1H), 7.72 (d, J = 6.9 Hz, 2H), 11.39 (bs, 1H); 13C NMR (75 MHz, CDCl3): delta = 27.2, 32.6, 127.2, 128.2, 129.4, 132.3, 137.5, 145.9, 179.0, 197.8. 108-55-4, As the paragraph descriping shows that 108-55-4 is playing an increasingly important role.
Reference£º
Article; Sivak, Ivan; Berke?, Du?an; Ko?i?ek, Jozef; Kolarovi?, Andrej; Tetrahedron Letters; vol. 57; 10; (2016); p. 1079 – 1082;,
Tetrahydropyran – Wikipedia
Tetrahydropyran – an overview | ScienceDirect Topics