333366-27-1

Upstream product

• 4378-13-6 (O-tert-butyl)-L-threonine 

Relevant academic research and scientific papers

Solid-phase Staudinger ligation from a novel core-shell-type resin: A tool for facile condensation of small peptide fragments

Solid-phase Staudinger ligation of small peptides was performed on a novel core-shell-type resin. Solid-phase Staudinger ligation was mediated by synthetic solid-supported phosphinothiol, which was readily prepared by a straightforward synthetic route. This protocol afforded final peptide products in excellent yields and purities and thus could provide the opportunity to facilitate a simple manipulation for condensation of peptide fragments. In particular, the resulting resin could be recycled in a successful manner.

Synthesis and application of sialic acid-containing building blocks for glycopeptide libraries. Establishing glycosylation conditions

Three different sialic acid-containing building blocks (6-8) were synthesized for use in solid-phase glycopeptide libraries. Investigation of the conditions for glycosylation of threonine (Thr) with various sialic acid donors revealed that the best results were obtained by coupling glycosyl xanthate 2 to the acceptors Fmoc-Thr-OH (5) or the α-azido acid analogue of Thr, 4. Among several catalysts employed, phenylsulfanyl triflate (PST) afforded the best yields. Both the N-Fmoc and α-azido analogues of Thr allowed glycosylation with good stereoselectivity in 80% (→ 8) and 84% (→ 6) yield, respectively. Introduction of a phenylthio group in the 3 position of the sialic acid donor 3, to assist the stereoselective outcome of the glycosylation reaction, gave good results; however difficulties in the removal of the phenylthio auxiliary group made this route less attractive. Both building blocks 6 and 8 were successfully introduced in solid-phase glycopeptide synthesis. Interestingly, alkaline deprotection of the Fmoc group of 8, necessary for subsequent introduction of amino acids, resulted in an immediate attack of the α-amino group on the sialic acid methyl ester to form the lactam 14. This side reaction was also observed during reduction of the azido acid building block 6 under alkaline conditions, but could be suppressed by performing the reduction under acidic conditions. Lactam formation was completely avoided by hydrolysis of the methyl ester prior to reduction of the azide. The Royal Society of Chemistry 2000.

Improved solid-phase peptide synthesis method utilizing alpha-azide-protected amino acids.

[structure: see text]. Pure alpha-azido acids were prepared using an efficient diazo transfer method followed by buffered workup. These building blocks were used to prepare small peptides on Wang resin by two approaches. Peptides prone to diketopiperazine formation were prepared in good yields by coupling acids to resin bound iminophosphoranes during Fmoc-Wang synthesis. The iminophosphoranes can also be hydrolyzed under neutral conditions to provide unprotected amines ready for further coupling.