Triethylamine → Phenyl pyridazin-4-ylcarbamate

Participants

Reaction Conditions

Reaction Steps

A stirred suspension of 2.6 grams (0.027 mole) of 4-aminopyridazine (prepared as in Example 1, Step A) in 100 ml of tetrahydrofuran is cooled to 0° C. and 4.6 ml (0.033 mole) of triethylamine is added in one portion. A solution of 4.1 ml (0.033 mole) of phenyl chloroformate in tetrahydrofuran is added dropwise during a 30 minute period. Upon completion of addition the reaction mixture is allowed to warm to ambient temperature where it is stirred for three days. The reaction mixture is concentrated under reduced pressure to a residue. The residue is taken up in 500 ml of chloroform and filtered to collect 1.9 grams of phenyl N-(4-pyridazinyl)carbamate; m.p. 184°-185° C. The filtrate is washed with water, then dried with magnesium sulfate. The mixture is filtered and the filtrate placed on a column of silica gel. Further elution is accomplished using 10% methanol in methylene chloride. The appropriate fractions are combined and concentrated under reduced pressure to yield an additional 1.8 grams of phenyl N-(4-pyridazinyl)carbamate. The nmr spectra are consistent with the proposed structure. The reaction is repeated several times.

Provenance & Evidence