Organic and Medicinal Chemistry Letters

Table 7 Effect of solvent and base on the yield of 12

From: β-Keto esters from ketones and ethyl chloroformate: a rapid, general, efficient synthesis of pyrazolones and their antimicrobial, in silico and in vitro cytotoxicity studies

Base	Ketone (eq.)	Solvent	Temperature	Yield (%)^a
LiHMDS (1.0M THF) (1 eq.)	3	THF	−78°C	68
LiHMDS (1.0M THF) (2 eq.)	3	Toluene	−78°C	56
KHMDS (3 eq.)	7	Toluene	−78°C	42
NaH (2 eq.)	50	THF	−78°C	17
NaOMe (2 eq.)	75	THF	Reflux	0
KOtBu (3 eq.)	10	THF	25°C	19
LiHMDS (1.0M THF) (3.5 eq.)	7	Toluene	−50°C to−30°C	92

^aIsolated yield.

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