Fine Chemical Synthesis Through Supported Bases

Organic bases represent a class of widely utilized catalysts in organic synthesis. During the last decade many research groups have been involved in the challenge of supporting homogeneous catalysts on the surface of organic and inorganic supports with the aim of producing efficient heterogeneous and reusable catalysts. Among these catalysts organic bases (i.e. amines, guanidines, etc.) have received particular attention. The present review shows the developments made during the last twenty years in the area of preparing, characterizing and applying supported organic bases for the synthesis of fine chemicals. The methods for the preparation of the supported catalysts are briefly discussed. Particular attention is paid to find possible correlations between the methodologies utilized to prepare the solid catalysts and their efficiency in model reactions of general interest; in addition the identification of possible leaching phenomena and the approaches to face the problem of preventing the catalyst deactivation are considered. The complexity of the supported base catalysts, the difficulty frequently encountered by reactants in reaching the active sites and the role played by the unfunctionalized surface of the support are also discussed together with the description of the efficient recovery and reusability of these hybrid catalysts. Finally, after some general conclusions, future trends are presented.