Carbon Tetrachloride → Ethyl 2-chloro-4-methyl-1,3-oxazole-5-carboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To 1.50 g (0.016 mol) of N-isopropylcyclohexylamine in 20 ml of dry THF at -78° C. was added, under nitrogen, 4.1 ml of 2.4 M BuLi in hexane. The solution was stirred at -78° C. for 5 min. A solution of 1.55 g (0.01 mol) of the compound of Example 1, in 10 ml of THF, was added dropwise to the above lithium N-isopropylcyclohexylamide solution. The reaction mixture turned deep red. After 5 min. of stirring, 5 ml of CCl4 was added to the red solution and the reaction mixture was stirred at -78° C. for 1 hr. Thereafter, the reaction mixture was poured into water and extracted with 100 ml of ether. The ether solution was washed with 1 N HCl, dried (MgSO4) and concentrated under reduced pressure. The residue was chromatographed on silica gel using 10% ether/petroleum ether as eluant. The first 800 ml of eluate gave a solid which was recrystallized from hexane at low temperature to give 200 mg of ethyl 2-chloro-4-methyl-5-oxazolecarboxylate as white solid, mp 61°-72° C. An additional 330 mg, mp 55°-58° C., was obtained by concentration of the mother liquor and distillation of the residue; total yield 29%.

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