G. C. Barrett
1978
Citations
0
Influential Citations
5
Citations
Journal
Tetrahedron
Abstract
Abstract 5-(2'-Benzamidoacyloxy)thiazoles are formed by the reaction of N-thiobenzoyl-α-amino-acids with trifluoroacetic anhydride. Corresponding esters on similar treatment undergo isosteric S-O exchange, giving N-benzoyl-α-amino-acid esters. While these are further examples of the differences shown in the reactions of N-(2-carboxyalkyl)thiobenzamides compared with their benzamide analogues, Nα-thiobenzoyl-α-amino-acid amides are found to undergo cyclisation in trifluoroacetic anhydride to give 5-trifluoroacetamido-thiazoles, following the same reaction path as their N-benzoyl analogues. Terminal N-thiobenzoyl dipeptides give 5-(N-2-carboxyalkyl) trifluoroacetamido-thiazoles on treatment with trifluoroacetic anhydride, and it is established that trifluoroacetic anhydride fails to cleave the amide group of terminal N-thioacyl dipeptides, and is therefore not a suitable reagent for Edman-type sequence analysis of polypeptides. The present work completes a project establishing routes from α-amino-acids to thiazoles carrying a heteroatom (O, N or S) at the 5-position.