Solid-Phase Organic Synthesis and Catalysis: Some Recent Strategies Using Alumina, Silica, and Polyionic Resins

Basudeb Basu,Susmita Paul

doi:10.1155/2013/614829

Abstract

Solid-phase organic synthesis (SPOS) and catalysis have gained impetus after the seminal discovery of Merrifield’s solid-phase peptide synthesis and also because of wide applicability in combinatorial and high throughput chemistry. A large number of organic, inorganic, or organic-inorganic hybrid materials have been employed as polymeric solid supports to promote or catalyze various organic reactions. This review article provides a concise account on our approaches involving the use of (i) alumina or silica, either having doped with metal salts or directly, and (ii) polyionic resins to either promote various organic reactions or to immobilize reagents/metal catalysts for subsequent use in hydrogenation and cross-coupling reactions. The reaction parameters, scopes, and limitations, particularly in the context of green chemistry, have been highlighted with pertinent approaches by other groups.

Highlights

The concept of solid-phase organic synthesis (SPOS) dates back mid-1940s, and the solid-phase peptide synthesis in 1960s developed by Merrifield has been a pioneering work [1]
According to Paul Anastas—one of the founders of the concepts of green chemistry, “Catalysis is a foundational stone of Green Chemistry” [11, 12]
Polymer supports play a critical role in combinatorial chemistry, and solid-phase organic synthesis continues to grow in importance [16,17,18,19,20,21,22,23]

Summary

Introduction

The concept of solid-phase organic synthesis (SPOS) dates back mid-1940s, and the solid-phase peptide synthesis in 1960s developed by Merrifield has been a pioneering work [1]. Good dispersion of the active reagent sites, involving high selectivity, easier work-up, and improved efficiency are attractive features for solid-phase technology Both inorganic and organic polymers have been employed to mediate or promote organic reactions [28,29,30]. Notable features of the use of KF doped with alumina (KF/alumina) are (i) the use of NaOBut can be avoided; (ii) conditions are not ligand-specific; (iii) solvent-free reactions generally give better yields; (iv) applicable to both bromoarenes and N-heteroaryl bromides; (v) varying proportions of KF per gram of alumina offer selectivity; and (vi) recycling of the solid surface is possible.

NHR or NR2

Reactions Promoted by Silica Gel

Reactions on Organic Polymer Support

C H3 CO

Conclusion