Citric Acid → 6-Hydroxy-2-naphthaldehyde

Temperature

-78 °C

To a stirred cooled mixture of 6-bromo-2-hydroxynaphthalene (25.3 g, 0.113 mol) in THF (600 mL) at −78° C. was added n-BuLi (2.5 M, 100 mL, 0.250 mol) dropwise. The mixture turned yellow and the temperature rose to −64° C. After ca 5 min a suspension appeared. After addition, the mixture was maintained at −78° C. After 20 minutes, a solution of DMF (28.9 mL, 0.373 mol) in THF (100 mL) was added over 20 minutes. After addition, the mixture was allowed to warm slowly to RT. After 1 hour, the mixture was poured in ice/water (200 mL). To the mixture citric acid was added to a pH of 5. The mixture was stirred for 0.5 hour. Ethyl acetate (200 mL) was added and the organic layer was separated and washed with brine (100 mL), dried over Na2SO4 and concentrated. To the residue was added heptane with 20% ethyl acetate (ca 50 mL) and the mixture was stirred for 1 hour. The mixture was filtered and the solid was washed with ethyl acetate and dried in vacuo to afford 16 g of the title compound.

1. temperatureTo a stirred cooled
2. customrose to −64° C
3. waitAfter ca 5 min a suspension appeared
4. additionAfter addition
5. additionAfter addition
6. temperatureto warm slowly to RT
7. waitAfter 1 hour
8. customthe organic layer was separated
9. washwashed with brine (100 mL)
10. dry with materialdried over Na2SO4
11. concentrationconcentrated
12. additionTo the residue was added heptane with 20% ethyl acetate (ca 50 mL)
13. stirringthe mixture was stirred for 1 hour
14. filtrationThe mixture was filtered
15. washthe solid was washed with ethyl acetate
16. customdried in vacuo

ORD record

ord-b886a5859a56467ea141e5373dcd95c9

Source dataset

uspto-grants-2011_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07879893B2