Methyl chloroformate → HCID 58515775, compound

Participants

Reaction Conditions

Reaction Steps

To a mixture of 4-(5-bromo-2-ethylphenyl)-2,2,6,6-tetramethylpyran-3,5-dione (0.15 g, 0.42 mmol), 4-chloropyrazole (0.065 g, 0.63 mmol), L-proline (0.049 g, 0.42 mmol), copper(I) iodide (0.080 g, 0.42 mmol) and anhydrous powdered potassium phosphate (0.36 g, 1.68 mmol) is added degassed anhydrous dimethylsulfoxide (1.5 ml). This mixture is then heated at 160° C. under microwave irradiation for 30 minutes, followed by cooling to room temperature, dilution with dichloromethane (150 ml) and washing with 1M aqueous hydrochloric acid (2×50 ml). The organic fractions are combined, dried over anhydrous magnesium sulfate, then concentrated in vacuo. Diethyl ether is then added to the crude oil to precipitate the product, which is filtered and re-dissolved in dichloromethane (20 ml). To this solution is then added triethylamine (0.16 ml, 1.16 mmol) followed by methyl chloroformate (0.090 ml, 1.16 mmol) and stirring at room temperature for 3 hours. The solvents are removed under reduced pressure, and the residue is purified directly by column chromatography on silica gel (hexane/ethyl acetate 3:1 ratio) to afford carbonic acid 4-[5-(4-chloropyrazol-1-yl)-2-ethylphenyl]-2,2,6,6-tetramethyl-5-oxo-5,6-dihydro-2H-pyran-3-yl ester methyl ester (0.075 g) as a colourless oil.

Provenance & Evidence