Ethyl Acetoacetate → Sodium 4-(ethoxycarbonyl)-2-(methoxycarbonyl)-3-methylcyclopenta-1,3-dienolate

Participants

Reaction Conditions

Reaction Steps

In a 12 L round bottom flask, NaH (60% dispersion in mineral oil, 159 g, 3985 mmol) was added in portions to stirred anhydrous THF (4004 mL) to give a gray suspension. The mixture was cooled to about 5° C. in an ice/salt bath before ethyl acetoacetate (506 mL, 3985 mmol, Alfa Aesar) in anhydrous THF (200 mL) was added dropwise via an addition funnel over about 1 h during which time the temperature gradually increased to about 18° C. After the addition was complete, the reaction was stirred at ambient temperature for about 1 h and then a solution of methyl 4-chloroacetoacetate (230 mL, 1993 mmol, Oakwood) in anhydrous THF (200 mL) was added dropwise via an addition funnel over about 1 h. The resulting mixture was stirred at ambient temperature for about 2 h and then heated at about 50° C. for about 16 h. The reaction mixture was concd in vacuo. The orange solid was cooled to about 5° C. and an ice/water mixture (2 L) was added. The suspension was mixed by rotating on the rotovap without vacuum for about 30 min. The solid was collected by filtration and washed with ice-cold water (750 mL). Once most of the solvent (about 90%) had been removed, the wet solid was triturated with MeCN (750 mL), stirred for about 30 min and then the solid was collected by filtration while washing with Et2O (2×500 mL). The solid was dried in air for about 16 h and then in vacuo at about 55° C. to give sodium 4-(ethoxycarbonyl)-2-(methoxycarbonyl)-3-methylcyclopenta-1,3-dienolate (485 g, 98%): 1H NMR (DMSO-d6) δ 3.95 (q, J=7.1 Hz, 2H), 3.48 (s, 3H), 2.69 (q, J=2.0 Hz, 2H), 2.47 (t, J=2.1 Hz, 3H), 1.15 (t, J=7.1 Hz, 3H).

Provenance & Evidence