Linneaus C. Dorman

Purification of γ-Benzyl and γ-Methyl L-Glutamate N-Carboxyanhydrides by Rephosgenation

Abstract Rephosgenation of N-carboxyanhydrides of γ-benzyl and y-methyl L-glutamates, vs multiple recrystallizations, is a very efficient method for obtaining highly purified N-carboxyanhydrides, from which very high MW (0.98-1.5 × 106 Daltons) polymers can be derived.

Determination of the availability of carbodiimide-activated N-protected amino acids in solid phase peptide synthesis

Abstract A new method is described for the determination of the availability of carbodiimide-activated N-protected amino acids in solid phase peptide synthesis. The method involves the addition of a second nucleophile to a solid phase coupling reaction at different time intervals and measuring the amount of activated amino acid intercepted. Using the DCCI-mediated coupling reaction of Boc-Ala-OH and H-Gly-O-resin with H-Gly-O-tBu as the second nucleophile, it was determined that ca . 61% of the theoretical maximum amount of activated Boc-Ala-OH was available after 8 hr of reaction.