Ethyl oxoacetate → Ethyl 4-oxo-3,4-dihydro-2H-pyran-2-carboxylate

A solution of glyoxylic acid ethyl ester, polymer form (2.02 g, 8.9 mmol) and (3-methoxy-1 methylene-allyloxy)trimethylsilane (1.9 ml, 8.9 mmol, Danishefsky's diene) in benzene (12 ml) was placed under nitrogen. Zinc chloride (0.5 N in tetrahydrofuran, 8.9 ml, 4.45 mmol) was added and the reaction stirred at ambient temperature for 72 hours. The mixture was concentrated in vacuo, diluted with ethyl acetate (100 ml) and washed with 1 N hydrochloric acid (20 ml), saturated sodium bicarbonate (20 ml), and brine (20 ml). The organic layer was dried (Na2SO4), filtered, and the solvent evaporated in vacuo. The residue was purified by silica gel chromatography using a mixture of ethyl acetate/hexane (1:2) as eluent. Pure fractions were collected and the solvent evaporated in vacuo which afforded 1.2 g (75%) of 4-oxo-3,4-dihydro-2H-pyran-2-carboxylic acid ethyl ester as an oil.

1. concentrationThe mixture was concentrated in vacuo
2. additiondiluted with ethyl acetate (100 ml)
3. washwashed with 1 N hydrochloric acid (20 ml), saturated sodium bicarbonate (20 ml), and brine (20 ml)
4. dry with materialThe organic layer was dried (Na2SO4)
5. filtrationfiltered
6. customthe solvent evaporated in vacuo
7. customThe residue was purified by silica gel chromatography
8. additiona mixture of ethyl acetate/hexane (1:2) as eluent
9. customPure fractions were collected
10. customthe solvent evaporated in vacuo which

ORD record

ord-92bd6faa833b4c6397d99a0800f07e7f

Source dataset

uspto-grants-2006_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07019026B1