N-Acetoacetylation with diketene

Mercuric acetate Mercuric salts as catalysts N-Acetoacetylation with diketene... 

Acetoacetic ester s. y -Keto-carboxylic acid esters C-Acetoacetylation with diketene 24,708 N-Acetoacetylation with diketene 24, 334, 708 Acetone as reagent (s. a. under Sensitizers) 22, 324 Acetonitrile... 

N-Acetoacetylation with diketene of N-silylcarboxylic acid amides... 

N-Acetoacety lotion. The N-acetoacetylation of amides with diketene is markedly improved if it is carried out in the presence of iodotrimcthylsilanc (generated in situ). The reactive reagent is probably a. 

N-Protection in peptide synthesis. Diketene reacts with an amino ester hydrochloride in ethanol at 0-5° in the presence of 1 equivalent of sodium ethoxide or a tertiary amine to give the often crystalline and easily purified N-acetoacetyl derivative (1). After peptide synthesis the protective group is removed by treatment with phenylhydrazine, which affords l-phenyl-3-methyl-5-pyrazolone. 

Xylidine is used in the preparation of N-acetoacetyl-2,4-xylidide (AAX), an intermediate in pigment manufacture it is accessible by the reaction of 2,4-xyli-dine with diketene. 

The N-benzyloxycarbonyl derivatives of serine and threonine can be converted into their t-butyl esters, using isobutene and an acid catalyst, only after protection of the alcohol group by reaction with diketen to give the o-acetoacetyl derivatives. The alcohol group can then be unmasked by treatment with hydrazine. 

A soln. of N-trimethylsilyl-2-pyrrolidone and diketene in dry benzene refluxed 4 hrs. in the presence of a catalytic amount of triethylamine, a little water added, and warmed 10 min. at 60° on a water bath -> N-acetoacetyl-2-pyrrolidone. Y 89%. F. e. and different reaction with silylated prim, amides s. Y. Yamamoto and H. Kimura, Chem. Pharm. Bull. 24, 1236 (1976). 

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