Heterocycle library synthesis alkylation

In a separate study, Ohberg and Westman applied the same PS-DMAP in a one-pot microwave-induced base-catalyzed reaction of N-aryl and N-alkyl amino acids (or esters) and thioisocyanates for the library synthesis of thiohydantoins (Scheme 7.115) [136]. Thiohydantoins are of interest due to their ease of preparation and the range of biological properties associated with this heterocyclic ring system. The use of PS-DMAP as the base in this reaction gave slightly lower yields compared to when triethylamine (TEA) was used, but it resulted in a cleaner reaction mixture and an easier purification procedure. Cyclizations of a number of N-substituted... 

A variety of heterocyclic compounds have been derived from the condensation of aldehydes with a-amino acids. Imines 1 (Fig. 3) are often used as intermediates in organic synthesis and are the starting point for chemical reactions such as cycloadditions, condensation reactions, and nucleophilic additions. The formation of imines via condensation of amines with aldehydes was first adopted for the reductive alkylation of resin-bound amino acids [29-31]. Imines have now been used as synthetic intermediates in the generation of a range of heterocyclic combinatorial libraries. 

---