N-Carboxyamino acid anhydride

Synthesis of amino acids having pendant nucleic acid bases and polymerization of their N-carboxyamino acid anhydride ( NCA ) derivatives... 

A series of new amino acid derivatives having pendant nucleic acid bases was prepared by the reaction of L-lysine and L-glutamic acid with the nucleic acid bases. These amino acids were further polymerized by using the N-carboxyamino acid anhydride ( NCA ) method. Alternatively, the nucleic acid base substituted poly-L-lysines were also prepared by using polymer reactions which include the reaction of carboxyethyl derivatives of the bases onto poly-L-lysine. Physico-chemical properties of the polymers obtained were given. 

Reaction of N-Carboxyamino Acid Anhydrides with Proteins. A number of proteins have been modified chemically with jV-carboxy an-... 

PMLG was chosen, because this pol3nner has been synthesized in the industrial scale in Japan. PMLG was prepared by the polymerization of N-carboxyamino acid anhydride. The viscosity-average molecular weight is about 60,000 which was determined by the intrinsic viscosity of dichloroacetic acid solution at 25 C. 

An interesting approach to obtain peptides in which the purine or pyrimidine residues were correctiy spaced for interaction with the nucleic acids, was made by using a spacer amino acid [49]. Serine was used as a spacer and several protected tetrapeptides, e.g., a-N-t-BOC-L-seryl-D,L-P-(thymin-l-yl)ala-nyl-L-seryl-D,L-P-(thymin-l-yl)alanine, ethyl ester, were synthesized but little was reported about their solution properties and interactions with the nucleic acids. The polymerization of the nucleic acid base-substituted L-lysine derivatives by N-carboxyamino acid anhydride method was also reported [52, 53]. 

IV-Carboxyamino Acid Anhydrides. Synthesis of N-carboxyamino acid anhydrides (NCAs) is accomplished by the reaction of the zwitterionic unprotected amino acid with triphosgene at elevated temperatures (eq 7). Wilder and Mobashery reported a milder version of this reaction, utilizing A -t-butoxycarbonyl-a-amino acids in the presence of a stoichiometric quantity of Triethylamine and 1/3 equiv of triphosgene (eq 8) the reaction is believed to proceed via a chloroformic A/-r-butoxycarbonyl-a-amino acid anhydride intermediate to give the corresponding NCA. There are many synthetic routes to NCAs however, the use of triphosgene in the preparation of NCAs provides a facile, safe, mild, and practical entry to these important molecules. 

Beilstein Handbook Reference) AI3-24983 Benzoic acid, 2-(carboxyamino)-, cyclic anhydride BRN 0136786 N-Carboxyanthranilic acid cyclic anhydride N-Carboxyanthranilic anhydride EINECS 204-2660 HSDB 5017 Isatoic acid anhydrtde Isatoic anhydride NSC 104662. 

---