Procedures are described for converting primary amines into their well-crystalline trichloroacetyl-derivatives by treatment with hexachloroacetone under mild conditions. Although secondary aromatic N-methylamines are unaffected by hexachloroacetone, saturated heterocyclic amines react vigorously.A mechanistic study using 2-amino-4-t-butylthiazole showed that the reaction is first order in hexachloroacetone, second order in amine, and base-catalysed; there is no appreciable kinetic isotope (H/D) effect nor accumulation of intermediates during the reaction. A sequence which accommodates these results is suggested.N-SUBSTITUTED trichloroacetamides can be prepared by treating primary and secondary amines with trichloroacetyl chloride and primary amines with ethyl trichloroacetate,2 and, in low yield, by rearrangement of alkyl acet imidates .3 Some Nt richloroacet ylphen ylamines have also been obtained from the amines using aqueous hexachloroacetone; this ketone (in dimethyl sulphoxide) has been used for the trichloroacetylation of dipep tide^.^ The present work stemmed from the observation that 4-methyl-and 5-ethyl-2-trichloroacetamidothiazole, originally prepared using trichloroacetyl chloride,6 are formed readily from the 2-aminothiazoles and hexachloroacetone. A mechanistic investigation
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