Yasuhiro Nishiyama

Simple approach towards the synthesis of 5-methyl-2-hydroxypyrazine derivatives from dipeptidyl chloromethyl ketones

Abstract 5-Methyl-2-hydroxypyrazine derivatives were easily synthesized by short reflux of dipeptidyl chloromethyl ketone hydrochlorides in MeOH.

Temporary Nα-deprotection/reprotection procedure to facilitate the purification of protected peptide fragments for use in convergent solid phase peptide synthesis

Abstract N -Terminal Fmoc group of the fully protected peptide resin prepared by stepwise solid phase petide synthesis in combination with N α -Fmoc protection, TFA-stable side-chain protections including newly developed 2-adamantyloxycarbonyl (2-Adoc) group, and TFA-cleavable solid support, was temporarily removed to give the polar intermediate, profragment , which was favorable for the purification by reversed phase mode rather than the N -terminal protected homolog. The purified profragment could be readily converted to the N -terminal protected fragment by treatment with Fmoc-OSu in short period for use in convergent solid phase peptide synthesis.

Amino Acids and Peptides. Part 48. 1 Studies on the Structure of an Unexpected Reaction Product from Dipeptidyl Chloromethyl Ketone during Acid Hydrolysis 2

During the course of the synthesis of peptidyl chloromethyl ketones (CMKs), it was revealed that amino acid recovery after acid hydrolysis (6 mol dm -3 HCl, 110 °C, 20 h) of dipeptidyl chloromethyl ketones was markedly low (7.1–33.7%) owing to the formation of 5-methylpyrazin-2(1H)-one derivatives during the acid hydrolysis.

Amino acids and peptides. Part 38. Development of a new amino-protecting group, 2-adamantyloxycarbonyl, and its application to peptide synthesis

A new Iµ-amino protecting group, 2-adamantyloxycarbonyl (2-Adoc), was developed, and its application to the solid-phase synthesis of protected peptides was demonstrated in combination with Nα-fluoren-9-ylmethoxycarbonyl (Fmoc) protection and trifluoroacetic acid (TFA)-cleavable resin support. The 2-Adoc group was applied successfully also to the solution-phase peptide synthesis depending on tert-butoxycarbonyl (Boc)-chemistry.

Development of a new amino-protecting group, 2-adamantyloxycarbonyl (2-adoc), and its application to the solid-phase synthesis of protected peptides

A new Iµ-amino protecting group, 2-adamantyloxycarbonyl (2-Adoc) has been developed, and its application to the solid phase synthesis of the protected peptide has been demonstrated successfully in combination with Nα-fluoren-9-ylmethoxycarbonyl (Fmoc) protection and trifluoroacetic acid (TFA)-cleavable resin support.

Amino acids and peptides. Part 42. Application of the 2-adamantyloxycarbonyl (2-Adoc) group to the protection of the imidazole function of histidine in peptide synthesis

The Nim-2-adamantyloxycarbonyl (2-Adoc) group has been found to be both suitable for protection of the imidazole function of the histidine residue in peptide synthesis in terms of its stability to trifluoroacetic acid (TFA), tertiary amines and 1-hydroxybenzotriazole (HOBt), and in its reduction of the racemization rate during the coupling reaction. Nim-2-Adoc protection has also been applied successfully to the solid-phase synthesis of thyrotropin-releasing hormone which depends on tert-butoxycarbonyl (Boc)-chemistry.