Dimethylformamide → 3-Ethoxy-spiro[3.4]octa-2,6-dien-1-one

A solution of cyclopent-3-ene carboxylic acid (4.0 g, 36.0 mmol) and DMF (0.25 ml) in DCM (30 ml) at 0° was treated dropwise with oxalyl chloride (3.5 ml, 39.0 mmol). After 2 h the reaction mixture was concentrated in vacuo, the residual slurry diluted with Et2O (100 ml) and the resulting precipitate removed by filtration and the filtrate concentrated in vacuo. The resulting oil was diluted with Et2O (50 ml), treated with ethoxyacetylene (40% w/w solution in hexanes, 10 ml) followed dropwise with triethylamine (6 ml, 44.0 mmol) and the reaction stirred for 7 d. Filtration and concentration of the filtrate in vacuo followed by chromatography (SiO2, 5:1 EtOAc:hexanes) gave the title compound as a pale yellow oil (4.3 g, 73%); m/z (ES+, 70V) 164.9 (MH+).

1. concentrationAfter 2 h the reaction mixture was concentrated in vacuo
2. additionthe residual slurry diluted with Et2O (100 ml)
3. customthe resulting precipitate removed by filtration
4. concentrationthe filtrate concentrated in vacuo
5. additionThe resulting oil was diluted with Et2O (50 ml)
6. additiontreated with ethoxyacetylene (40% w/w solution in hexanes, 10 ml)
7. filtrationFiltration and concentration of the filtrate in vacuo

ORD record

ord-8f6e989318734b8a89e7730529b961dd

Source dataset

uspto-grants-2009_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07501437B2