4-Nitrophthalide → 4-Nitro-1,3-dihydroisobenzofuran

A suspension of 19.5 g of 1,3-dihydro-4-nitrobenzo[c]furan-1-one in 100 ml of boron trifluoride etherate was cooled to 0°-5° under nitrogen. 125 ml of a 1M solution of borane-tetrahydrofuran complex was added dropwise below 10°. The orange suspension was allowed to warm to ambient temperature (H2 evolution), and the reaction mixture exothermed to 30°. When the exotherm subsided (15-20 minutes), the mixture was refluxed 2.5 hours. The reaction mixture was cooled, decanted from some brown solids, and concentrated in vacuo to a yellow oil. The oil was cooled in an ice bath and acidified with dilute hydrochloric acid (H2 evolution), then diluted with 300 ml water, and the suspension was extracted with ether. The organic solution was washed with brine, dried over magnesium sulfate, filtered, and the solvent evaporated in vacuo. The resulting yellow solid was purified by chromatography, eluting with methylene chloride to give 15.4 g of 1,3-dihydro-4-nitrobenzo[c]furan as a pale yellow solid, m.p. 104°-108°.

1. temperaturewas cooled to 0°-5° under nitrogen
2. customexothermed to 30°
3. custom(15-20 minutes)
4. temperaturethe mixture was refluxed 2.5 hours
5. temperatureThe reaction mixture was cooled
6. customdecanted from some brown solids
7. concentrationconcentrated in vacuo to a yellow oil
8. temperatureThe oil was cooled in an ice bath
9. additiondiluted with 300 ml water
10. extractionthe suspension was extracted with ether
11. washThe organic solution was washed with brine
12. dry with materialdried over magnesium sulfate
13. filtrationfiltered
14. customthe solvent evaporated in vacuo
15. customThe resulting yellow solid was purified by chromatography
16. washeluting with methylene chloride

ORD record

ord-8859626848b04d779af5bf675e82a608

Source dataset

uspto-grants-1986_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04578108