Malonic Acid → (E)-6-[2-(2,6-Dichlorophenyl)ethenyl]-3,4,5,6-tetrahydro-4-hydroxy-4-methyl-2H-pyran-2-one

Temperature

-20 °C

2-Acetoxypropene (3.3 ml, 30 mmole) and tri-n-butyltin methoxide (5.7 g, 24 mmole) were combined and stirred at 60°-70° C. under N2 for 1 hour then placed under vacuum for an additional 30 minutes. 3-(2,4-Dichlorophenyl)propenal (4 g, 20 mmole) was added and the reaction mixture was stirred at 70° C. under N2 for 4 hours. The clear reaction mixture was then cooled, treated with malonic acid (1 g, 10 mmole) in ether (20 ml) and refluxed for 30 minutes. After cooling to -20° C., the reaction mixture was filtered and the precipitate was washed with ether (4×10 ml). The ethereal solutions were combined, evaporated and the residual oil was chromatographed on a 60 mm column with 15 cm of silica gel (230-400 mesh). Elution with chloroform-methanol (99:1, v:v; 2.0 L) provided the title compound as a thick yellow oil (4.2 g, 81%); pmr CDCl3) 2.2 (3H, s), 2.73 (2H, d), 4.73 (H, m), 6.10 (H, dd).

1. waitthen placed under vacuum for an additional 30 minutes
2. stirringthe reaction mixture was stirred at 70° C. under N2 for 4 hours
3. temperatureThe clear reaction mixture was then cooled
4. temperaturerefluxed for 30 minutes
5. filtrationthe reaction mixture was filtered
6. washthe precipitate was washed with ether (4×10 ml)
7. customevaporated
8. customthe residual oil was chromatographed on a 60 mm column with 15 cm of silica gel (230-400 mesh)
9. washElution with chloroform-methanol (99:1, v:v; 2.0 L)

ORD record

ord-ab1bffe49299493cb67288ee0014c836

Source dataset

uspto-grants-1984_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04459422