Synopsis A new route for the synthesis of long chain N(alpha)-acyl-l-alpha-amino-omega-guamdine alkyl acid derivatives, with cationic or amphoteric character has been established. The general formula of these compounds is shown below. A physico-chemical and antimicrobial study of these products as a function of the alkyl ester or sodium salt (R), the straight chain length of the fatty acid residue (x) and the number of carbons between the omega-guanidine and omega-carboxyl group (n) has been investigated. The water solubility, surface tension, critical micelle concentration (c.m.c.) and minimum inhibitory concentration (MIC) against Gram-positive and Gram-negative bacteria (including Pseudomonas) has been determined. Dicyclohexylcarbodiimide has been used to condense fatty acids and alpha-amino-omega-guanidine alkyl acids. In these conditions protection of the omega-guanidine group is not necessary. The main characteristic of this synthetic procedure is the use of very mild experimental conditions (temperature, pH) to form the amide linkage which leads to pure optical compounds in high yield in the absence of electrolytes. The results show that some structural modifications, particularly the protection of the carboxyl group, promote variations of the surfactant and antimicrobial properties. Only those molecules with the blocked carboxyl group (cationic molecules, where R = Me, Et or Pr) showed a good surfactant and antimicrobial activity. When the carboxyl group was unprotected (amphoteric molecules, where R = Na(+)) the resulting compounds were inactive.
Trifluomacetylamino derivatives 01 benzo[ hlthiophene and thiophene ( 3r-d) have been obtained by Cunius rearrangement ofthe comsponding acyl azides (la-d) with trifluomacetic acid. The iodination of these amide derivatives wilh iodine under mild conditions leads to iodinated products in excellent yield, except in the case of the 3-trifluomacetylaminobenw[ blthiophene (3a), which only gives a polymeric residue.As part of o w research program' directed toward the development of methodologies suitable for the preparation of polycyclic heteroaromatic compounds, we required a method to introduce iodine in the a-position to the amide group of a thiophene ring. Moreover, it is well known that the 3(2)-aminothiophene and 3(2)-aminoben-~[hlthiophene are labik2 A solution to this problem requires the direct generation of the amide functionality.We have previously described the preparation of the EL-butyl carbamates of thiophene and benzouthiophene by Cunius rearrangement of the corresponding acyl azides in m-butyl alcohol under reflux.3 and studied their halogenation3 and their reactivity as dianions toward bis-electrophilic reagents.1 Also we have shown that a Curtius rearrangement reaction can be used for the synthesis of 2-trifluoroacetylaminothiophene (3d).'We now report on the extension of this method to the preparation of 3(2)-trifluoroacetylaminobenzo[b]thiophenes (3a) and (3b), and 3-uifluoroacetylaminothiophene (3c). These amide derivatives of thiophene and benzo[Uthiophene and the corresponding iodinated products are potential starting materials to obtain thienoand benzoMthienoindole derivatives either ~ a SRNl process, as we have previously described for 3-amino-2-chl~ropyridine,~ ory& their reactivity as organodimetallic reagents as we have previously reported for the tert-butyl carbamate analogs and for the amide (3d).l -
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