ChemicalBook CAS DataBase List 2H-1-Benzopyran-2-one, 4-bromo-

2H-1-Benzopyran-2-one, 4-bromo- synthesis

5synthesis methods

Product Name:2H-1-Benzopyran-2-one, 4-bromo-
CAS Number:938-40-9
Molecular formula:C9H5BrO2
Molecular Weight:225.0388

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Yield:938-40-9 96%

Reaction Conditions:

Stage #1: 4-hydroxy[1]benzopyran-2-onewith tetrabutylammonium bromide in toluene at 100;Inert atmosphere;
Stage #2: with phosphorous pentoxide in toluene; for 3 h;Inert atmosphere;Heating;

Steps:

4-Bromo-2H-chromen-2-one (1)

Modification of the literature method. 13 4-Hydroxycoumarin (5 g,30.8 mmol) in toluene (62 mL, 0.5 M) was heated under a N2 atmosphere at 100 °C. Bu4NBr (14.91 g, 46.3 mmol) was then added and the mixture was heated to become solution. P2O5 (8.75 g, 61.7 mmol) was added and the mixture was heated for 3 h. The hot upper organic layer was transferred to a separation funnel and the lower layer was extracted with boiling toluene (2 × 30 mL). The combined toluene layers were washed with aq 5% NaHCO3 (2 × 30 mL), water (30 mL), and brine (30 mL), dried (anhyd Na2SO4), and concentrated under vacuum to give compound 1 (6.65 g, 96%); mp 87-88 °C (toluene) (Lit.19 87-89 °C).

References:

Balalas, Thomas;Abdul-Sada, Alaa;Hadjipavlou-Litina, Dimitra J.;Litinas, Konstantinos E. [Synthesis,2017,vol. 49,# 11,art. no. SS-2016-Z0864-P,p. 2575 - 2583]

5101-44-0 Synthesis