1H-2-Benzopyran-1,4(3H)-dione

Preparation of 1 /-/-2-benzopyran-1 , 4(3/-/)-dione (Compound of formula (III))A stirred mixture of 2-acetylbenzoic acid (compound of formula (XI)) (1.00 Kg, 6.09 mol) and chlorobenzene (10.0 L) was treated with 5.5 molar hydrobromic acid in acetic acid (55 ml_) and bromine (310 ml_) then warmed to approximately 30 °C. After 3 hours water (10.0 L) was added and the reaction heated to reflux. After 3 hours the reaction was cooled to 60 °C and the organic layer removed. The aqueous layer was extracted with chlorobenzene (2.0 L) and the combined organic layers concentrated under reduced pressure to approximately 3.0 L. Propan-2-ol (5.0 L) was charged and the slurry cooled to 0 °C before being filtered and washed with propan-2-ol (2.0 L). The resulting solid was dried in vacuo at 50 °C to give the title compound (736 g, 75percent); Step 1: lH-Isochromene-l, 4(3H)-dione [00369] To a solution of 2-acetylbenzoic acid (8.458 g, 51.52 mmol) in acetic acid (50.0 mL, 879 mmol) was added 30 ml of 33percent HBr in acetic acid. Bromine (8.646 g, 54.10 mmol) was next added to the solution, and the reaction was heated to 40 °C with stirring for 30 min. The reaction mixture was poured into 300 ml water, the layers were separated, and the aqueous layer was extracted with 3 x 100ml DCM. Combined the organic layers and concentrated in vacuo to yield crude intermediate, which was dissolved in 25 ml acetic acid, 130ml toluene and 30 ml water. The resulting mixture was stirred at reflux overnight. The reaction was cooled to rt, and the layers were separated. The organic layer was concentrated in vacuo and purified by flash column ( 120g column, eluent 0-55percent EtOAc in hexane)to afford 5.24g (63percent) of title compound. NMR (400 MHz, Chloroform-d) δ 8.36 - 8.28 (m, 1 H), 8.17 - 8.07 (m, 1 H), 7.95 - 7.79 (m, 2H), 5.16 (s, 2H).

Molecular Weight:162.14
XLogP3:1.4
Hydrogen Bond Acceptor Count:3
Exact Mass:162.031694049
Monoisotopic Mass:162.031694049
Topological Polar Surface Area:43.4
Heavy Atom Count:12
Complexity:222
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes