Синтез та бромування пропаргільного аміду трифтороцтової кислоти

Abstract

Carboxylic acid amides are convenient reagents for organic synthesis, and are promising building blocks for obtaining a large number of acyclic and heterocyclic compounds. Among the various aliphatic, aromatic and heterocyclic amides, fluorine-containing derivatives are the least studied. The presence of a carbonyl group, a fluoroalkyl substituent and an alkylsubstituted amino functional groups determines the variety of transformations for this class of compounds. The introduction of an unsaturated alkyl substituent to the amide nitrogen atom and the presence of an additional nucleophilic center of the oxygen or nitrogen atom makes such amides promising for the study of their reactions with electrophilic reagents. The aim of this work is the synthesis of propargyl trifluoroacetic acid amide and the study of its interaction with bromine.Trifluoroacetic acid propargylamide was prepared from trifluoroacetic acid ethyl ester and propargylamine in tetrahydrofuran medium, its structure was confirmed by NMR1H and NMR19F spectra. It is known from the literature sources that the presence of a multiple bond and an additional intramolecular nucleophilic center in propargyl amines and amides creates the pre-conditions for the cyclization reaction under the action of halogen-containing electrophilic reagents. Such structural features are also characteristic for N-propargyltrifluoroacetamide, namely the multiple bond of the propargyl moiety and additional intramolecular nucleophilic centers of nitrogen and oxygen atoms. Under the action of bromine as an electrophilic reagent on N-propargyltrifluoroacetamide, the formation of both the coupling product and the cyclization with the formation of azetidine, oxazoline or oxazine heterocycles is possible. The bromination reaction of N-propargyltrifluoroacetamide was performed in dichloromethane with an equimolar amount of reagents in the presence of potash. According to the spectral data, the coupling product N- (2,3-dibromoprop-2-en-1-yl) trifluoroacetamide is formed, which is confirmed by the NMR1H and NMR19F spectra. The absence of the cyclization process can be explained via the lower nucleophilicity of the oxygen atom compared to sulfur.