Synthesis of azole-enriched cyclic peptides by a clean solid-phase-based cyclization-cleavage strategy. 
Naturally occurring azole-enriched cyclic peptides have broad biological and pharmacological activities.  Previous synthetic efforts have mainly concentrated on the preparation of individual target molecules in solution phase.  A solid-phase-based cyclitive cleavage strategy was deployed here for efficient library synthesis of azole cyclopeptide derivatives, which is part of our continuous efforts for the characterization of potent modulators of multidrug resistance efflux proteins.  Procedures were optimized to afford the azole cyclopeptides at high yield and purity, eliminating the need for any chromatographic purification steps.  This development is ideal for high throughput library synthesis and screening and will facilitate the ultimate discovery of novel azole cyclopeptides with potent biological activities.