Robert Ramage

NG-2,2,5,7,8-pentamethylchroman-6-sulphonyl-L-arginine: A new acid labile derivative for peptide synthesis

A new acid labile protecting group for the guanidino side chain functionality of arginine has been developed. NG-(2,2,5,7,8-Pentamethyl-chroman-6-sulphonyl)-L-arginine, prepared from Nα-benzyloxycarbonyl-L-arginine and 2,2,5,7,8-pentamethylchroman-6-sulphonyl chloride, is cleaved rapidly in trifluoroacetic acid (TFA) or 50% TFA in dichloromethane at room temperature.

An acid labile arginine derivative for peptide synthesis: NG-2,2,5,7,8-pentamethylchroman-6-sulphonyl-L-arginine

Abstract A trifluoroacetic acid (TFA) labile protecting group for the guanidine side chain function of arginine has been developed. NG-(2,2,5,7,8-Pentamethylchroman-6-sulphonyl-L-arginine is cleaved rapidly in TFA or 50% TFA in dichloromethane at room temperature. The preparations of Fmoc.Arg(Pmc).OH and Bnpeoc.Arg(Pmc).OH are described.

A solid phase approach to quinolones using the DIVERSOMER® technology

Abstract The first example of a library of the quinolone antibacterial agents prepared by solid phase organic synthesis is described. Results of these studies and the parallel synthesis, isolation, purification and analysis of eight quinolones are discussed.

Solid phase peptide synthesis: Fluoride ion release of peptide from the resin

Abstract A linkage to anchor the growing peptide chain has been designed in order to allow swift release of the peptide product by Bu4N+F. Preparation of the linker (4) is described.

Solid phase peptide synthesis of ubiquitin

Abstract The synthesis of ubiquitin has been achieved using N G -Pmc protection of the Arg residues. Throughout the synthesis the N α -Fmoc deprotection was followed by UV monitoring. Authenticity of the primary structure was confirmed by automated Edman sequencing and enzymatic degradation.

Design on an affinity-based Nα-amino protecting group for peptide synthesis: tetrabenzo[a,c,g,i]fluorenyl-17-methyl urethanes (Tbfmoc)

Abstract A new Nα-amino protecting group (Tbfmoc) has been designed to allow selective adsorption to porous graphitised carbon, thus allowing facile separation of Nα-acetylated truncated peptides generated as impurities in solid phase peptide synthesis.

Application of the NG-(2,2,5,7,8-pentamethylchroman-6-sulphonyl) derivative of FMOC-arginine to peptide synthesis

Abstract The trifluoroacetic acid labile pentamethylchromanylsulphonyl protecting group for the guanidino group of arginine has been used in conjunction with the base-labile Fmoc Nα protecting group for the synthesis of arginine-containing peptides.

Design of a versatile linker for solid phase peptide synthesis: Synthesis of C-terminal primary/seconary amides and hydrazides

Abstract An efficient, versatile linker for solid phase peptide synthesis, based upon the dibenzocyclohepta-1,4-diene system, has been developed for the synthesis of C-terminal primary/secondary amides and hydrazides.

Synthesis and application of a novel coupling reagent, ethyl 1-hydroxy-1H -1,2,3-triazole-4-carboxylate

Abstract An optimal coupling reagent, ethyl 1-hydroxy-1H-1,2,3-triazole-4-carboxylate (HOCt), has been designed and synthesised for application to solid phase peptide synthesis using Fmoc chemistry. It is used in combination with carbodiimide reagents, has very high coupling efficiency, and does not absorb at 302nm, thus allowing real-time monitoring of each coupling cycle. Its applications in the synthesis of endothelin analogues and difficult sequences are also discussed.

Dioxalanones as synthetic intermediates. Part 6. Synthesis of 3-deoxy-D-manno-2-octulosonic acid (KDO), 3-deoxy-D-arabino-2-heptulosonic acid (DAH) and 2-keto-3-deoxy-D-gluconic acid (KDG)

Abstract Three biosynthetically significant α-keto acids KDO ( 7 ), DAH ( 8 ) and KDG ( 9 ) have been synthesised via 5-ylidene-1,3-dioxalan-4-one intermediates formed by Wittig reactions of protected monosaccharide-derived aldehydes with the Wittig reagent ( 3 ).