VIBRATIONAL SPECTROSCOPY FOR OPTIMIZATION OF SOLID-PHASE ORGANIC SYNTHESES

VIBRATIONAL SPECTROSCOPY FOR OPTIMIZATION OF SOLID-PHASE ORGANIC SYNTHESES 

This chapter describes how Fourier transform infrared (FTIR) spectroscopy can be used to monitor solid-phase organic reactions directly on solid supports. Examples encompassing a range of reaction conditions are discussed to demonstrate the value of this method for optimization of solid-phase organic syntheses. 

Solid-phase organic syntheses typically use large excesses of reagents to drive reactions to completion so that, ideally, products liberated from resins should not require purification. Optimization of conditions is a critical part of solid-phase syntheses. Transfer of organic reactions in solution to a solid matrix is not a trivial undertaking, and lack of analytical methods accentuates this problem. Libraries prepared without adequate refinement of conditions tend to be of poor quality. For libraries so large that all the constituents cannot be fully characterized, well-optimized reaction conditions are absolutely essential. Techniques like split and pool, 2 for instance, can only be applied successfully after thorough optimization. 

Monitoring Solid-Phase Organic Synthesis by FTIR Spectroscopy 

Typical solid supports used in organic syntheses are resin beads formed from cross-linked polystyrene (PS 40-150 pm diameter), polystyrene- 

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