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

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Biochemistry

Background:

• Peptide synthesis is fundamental to drug discovery and materials science.
• Challenges exist in synthesizing peptides prone to side reactions like diketopiperazine formation.
• Efficient methods for preparing novel amino acid building blocks are in demand.

Purpose of the Study:

• To develop an efficient synthesis of pure alpha-azido acids.
• To utilize these building blocks for peptide synthesis, particularly for challenging sequences.
• To explore novel coupling strategies for solid-phase peptide synthesis.

Main Methods:

• Preparation of alpha-azido acids via diazo transfer and buffered workup.
• Solid-phase peptide synthesis using Fmoc-Wang resin.
• Coupling of alpha-azido acids to resin-bound iminophosphoranes.
• Hydrolysis of iminophosphoranes to yield free amines.

Main Results:

• Pure alpha-azido acids were successfully synthesized.
• Peptides prone to diketopiperazine formation were obtained in good yields.
• Resin-bound iminophosphoranes facilitated efficient coupling.
• Neutral hydrolysis of iminophosphoranes provided unprotected amines for further elaboration.

Conclusions:

• The diazo transfer method provides efficient access to alpha-azido acid building blocks.
• Coupling alpha-azido acids to resin-bound iminophosphoranes is a viable strategy for synthesizing challenging peptides.
• This method offers a versatile approach for peptide modification and synthesis.