Solid-phase synthesis of heterocyclic aromates: applicability towards combinatorial chemistry; a review

Because of their biological activity, stability in vivo, the rigid spatial positioning of their substituents, and their synthetic challenges, heterocyclic aromates continue to be of interest to both academic and industrial medicinal chemists. Currently, many drug-like heterocyclic aromates are prepared via solid-phase organic chemistry methods. This review examines the applicability of those methods towards combinatorial chemistry with respect to the basic demands of such an approach: 1) synthesis, work-up and subsequent purification should be easily automated enabling the efficient simultaneous synthesis of large numbers of highly pure compounds in a minimum amount of time, 2) large diversity among the ligands to be synthesized, 3) high conversion rates of the individual reaction steps, and 4) the use of commercially available starting materials. Although many methods have been developed for the synthesis of heterocyclic aromates, very few of the available methods enable the synthesis of highly diverse heteroaromatic libraries.